XFree86 server 4.x Design (DRAFT)
The XFree86 Project, Inc
19 December 2003
NOTE: This is a DRAFT document, and the interfaces described here are subject
to change without notice.
1. Preface
The broad design principles are:
o keep it reasonable
o We cannot rewrite the complete server
o We don't want to re-invent the wheel
o keep it modular
o As many things as possible should go into modules
o The basic loader binary should be minimal
o A clean design with well defined layering is important
o DDX specific global variables are a nono
o The structure should be flexible enough to allow future extensions
o The structure should minimize duplication of common code
o keep important features in mind
o multiple screens, including multiple instances of drivers
o mixing different color depths and visuals on different and ideally
even on the same screen
o better control of the PCI device used
o better config file parser
o get rid of all VGA compatibility assumptions
Unless we find major deficiencies in the DIX layer, we should avoid making
changes there.
2. The XF86Config File
The XF86Config file format is similar to the old format, with the following
changes:
2.1 Device section
The Device sections are similar to what they used to be, and describe hard-
ware-specific information for a single video card. Device Some new keywords
are added:
Driver "drivername"
Specifies the name of the driver to be used for the card. This
is mandatory.
BusID "busslot"
Specifies uniquely the location of the card on the bus. The pur-
pose is to identify particular cards in a multi-headed configura-
tion. The format of the argument is intentionally vague, and may
be architecture dependent. For a PCI bus, it is something like
"bus:slot:func".
A Device section is considered ``active'' if there is a reference to it in an
active Screen section.
2.2 Screen section
The Screen sections are similar to what they used to be. They no longer have
a Driver keyword, but an Identifier keyword is added. (The Driver keyword
may be accepted in place of the Identifier keyword for compatibility pur-
poses.) The identifier can be used to identify which screen is to be active
when multiple Screen sections are present. It is possible to specify the
active screen from the command line. A default is chosen in the absence of
one being specified. A Screen section is considered ``active'' if there is a
reference to it either from the command line, or from an active ServerLayout
section.
2.3 InputDevice section
The InputDevice section is a new section that describes configuration infor-
mation for input devices. It replaces the old Keyboard, Pointer and XInput
sections. Like the Device section, it has two mandatory keywords: Identifier
and Driver. For compatibility purposes the old Keyboard and Pointer sections
are converted by the parser into InputDevice sections as follows:
Keyboard
Identifier "Implicit Core Keyboard"
Driver "keyboard"
Pointer
Identifier "Implicit Core Pointer"
Driver "mouse"
An InputDevice section is considered active if there is a reference to it in
an active ServerLayout section. An InputDevice section may also be refer-
enced implicitly if there is no ServerLayout section, if the -screen command
line options is used, or if the ServerLayout section doesn't reference any
InputDevice sections. In this case, the first sections with drivers "key-
board" and "mouse" are used as the core keyboard and pointer respectively.
2.4 ServerLayout section
The ServerLayout section is a new section that is used to identify which
Screen sections are to be used in a multi-headed configuration, and the rela-
tive layout of those screens. It also identifies which InputDevice sections
are to be used. Each ServerLayout section has an identifier, a list of
Screen section identifiers, and a list of InputDevice section identifiers.
ServerFlags options may also be included in a ServerLayout section, making it
possible to override the global values in the ServerFlags section.
A ServerLayout section can be made active by being referenced on the command
line. In the absence of this, a default will be chosen (the first one
found). The screen names may optionally be followed by a number specifying
the preferred screen number, and optionally by information specifying the
physical positioning of the screen, either in absolute terms or relative to
another screen (or screens). When no screen number is specified, they are
numbered according to the order in which they are listed. The old (now obso-
lete) method of providing the positioning information is to give the names of
the four adjacent screens. The order of these is top, bottom, left, right.
Here is an example of a ServerLayout section for two screens using the old
method, with the second located to the right of the first:
Section "ServerLayout"
Identifier "Main Layout"
Screen 0 "Screen 1" "" "" "" "Screen 2"
Screen 1 "Screen 2"
Screen "Screen 3"
EndSection
The preferred way of specifying the layout is to explicitly specify the
screen's location in absolute terms or relative to another screen.
In the absolute case, the upper left corner's coordinates are given after the
Absolute keyword. If the coordinates are omitted, a value of (0,0) is
assumed. An example of absolute positioning follows:
Section "ServerLayout"
Identifier "Main Layout"
Screen 0 "Screen 1" Absolute 0 0
Screen 1 "Screen 2" Absolute 1024 0
Screen "Screen 3" Absolute 2048 0
EndSection
In the relative case, the position is specified by either using one of the
following keywords followed by the name of the reference screen:
RightOf
LeftOf
Above
Below
Relative
When the Relative keyword is used, the reference screen name is followed by
the coordinates of the new screen's origin relative to reference screen. The
following example shows how to use some of the relative positioning options.
Section "ServerLayout"
Identifier "Main Layout"
Screen 0 "Screen 1"
Screen 1 "Screen 2" RightOf "Screen 1"
Screen "Screen 3" Relative "Screen 1" 2048 0
EndSection
2.5 Options
Options are used more extensively. They may appear in most sections now.
Options related to drivers can be present in the Screen, Device and Monitor
sections and the Display subsections. The order of precedence is Display,
Screen, Monitor, Device. Options have been extended to allow an optional
value to be specified in addition to the option name. For more details about
options, see the Options (section 10., page 1) section for details.
3. Driver Interface
The driver interface consists of a minimal set of entry points that are
required based on the external events that the driver must react to. No non-
essential structure is imposed on the way they are used beyond that. This is
a significant difference compared with the old design.
The entry points for drawing operations are already taken care of by the
framebuffer code (including, XAA). Extensions and enhancements to frame-
buffer code are outside the scope of this document.
This approach to the driver interface provides good flexibility, but does
increase the complexity of drivers. To help address this, the XFree86 common
layer provides a set of ``helper'' functions to take care of things that most
drivers need. These helpers help minimise the amount of code duplication
between drivers. The use of helper functions by drivers is however optional,
though encouraged. The basic philosophy behind the helper functions is that
they should be useful to many drivers, that they should balance this against
the complexity of their interface. It is inevitable that some drivers may
find some helpers unsuitable and need to provide their own code.
Events that a driver needs to react to are:
ScreenInit
An initialisation function is called from the DIX layer for each
screen at the start of each server generation.
Enter VT
The server takes control of the console.
Leave VT
The server releases control of the console.
Mode Switch
Change video mode.
ViewPort change
Change the origin of the physical view port.
ScreenSaver state change
Screen saver activation/deactivation.
CloseScreen
A close screen function is called from the DIX layer for each
screen at the end of each server generation.
In addition to these events, the following functions are required by the
XFree86 common layer:
Identify
Print a driver identifying message.
Probe
This is how a driver identifies if there is any hardware present
that it knows how to drive.
PreInit
Process information from the XF86Config file, determine the full
characteristics of the hardware, and determine if a valid config-
uration is present.
The VidMode extension also requires:
ValidMode
Identify if a new mode is usable with the current configuration.
The PreInit function (and/or helpers it calls) may also make use
of the ValidMode function or something similar.
Other extensions may require other entry points. The drivers will inform the
common layer of these in such cases.
4. Resource Access Control Introduction
Graphics devices are accessed through ranges in I/O or memory space. While
most modern graphics devices allow relocation of such ranges many of them
still require the use of well established interfaces such as VGA memory and
IO ranges or 8514/A IO ranges. With modern buses (like PCI) it is possible
for multiple video devices to share access to these resources. The RAC
(Resource Access Control) subsystem provides a mechanism for this.
4.1 Terms and Definitions
4.1.1 Bus
``Bus'' is ambiguous as it is used for different things: it may refer to
physical incompatible extension connectors in a computer system. The RAC
system knows two such systems: The ISA bus and the PCI bus. (On the software
level EISA, MCA and VL buses are currently treated like ISA buses). ``Bus''
may also refer to logically different entities on a single bus system which
are connected via bridges. A PCI system may have several distinct PCI buses
connecting each other by PCI-PCI bridges or to the host CPU by HOST-PCI
bridges.
Systems that host more than one bus system link these together using bridges.
Bridges are a concern to RAC as they might block or pass specific resources.
PCI-PCI bridges may be set up to pass VGA resources to the secondary bus.
PCI-ISA buses pass any resources not decoded on the primary PCI bus to the
ISA bus. This way VGA resources (although exclusive on the ISA bus) can be
shared by ISA and PCI cards. Currently HOST-PCI bridges are not yet handled
by RAC as they require specific drivers.
4.1.2 Entity
The smallest independently addressable unit on a system bus is referred to as
an entity. So far we know ISA and PCI entities. PCI entities can be located
on the PCI bus by an unique ID consisting of the bus, card and function num-
ber.
4.1.3 Resource
``Resource'' refers to a range of memory or I/O addresses an entity can
decode.
If a device is capable of disabling this decoding the resource is called
sharable. For PCI devices a generic method is provided to control resource
decoding. Other devices will have to provide a device specific function to
control decoding.
If the entity is capable of decoding this range at a different location this
resource is considered relocatable.
Resources which start at a specific address and occupy a single continuous
range are called block resources.
Alternatively resource addresses can be decoded in a way that they satisfy
the conditions:
address & mask == base
and
base & mask == base
Resources addressed in such a way are called sparse resources.
4.1.4 Server States
The resource access control system knows two server states: the SETUP and the
OPERATING state. The SETUP state is entered whenever a mode change takes
place or the server exits or does VT switching. During this state all entity
resources are under resource access control. During OPERATING state only
those entities are controlled which actually have shared resources that con-
flict with others.
5. Control Flow in the Server and Mandatory Driver Functions
At the start of each server generation, main() (dix/main.c) calls the DDX
function InitOutput(). This is the first place that the DDX gets control.
InitOutput() is expected to fill in the global screenInfo struct, and one
screenInfo.screen[] entry for each screen present. Here is what InitOutput()
does:
5.1 Parse the XF86Config file
This is done at the start of the first server generation only.
The XF86Config file is read in full, and the resulting information stored in
data structures. None of the parsed information is processed at this point.
The parser data structures are opaque to the video drivers and to most of the
common layer code.
The entire file is parsed first to remove any section ordering requirements.
5.2 Initial processing of parsed information and command line options
This is done at the start of the first server generation only.
The initial processing is to determine paths like the ModulePath, etc, and to
determine which ServerLayout, Screen and Device sections are active.
5.3 Enable port I/O access
Port I/O access is controlled from the XFree86 common layer, and is ``all or
nothing''. It is enabled prior to calling driver probes, at the start of
subsequent server generations, and when VT switching back to the Xserver. It
is disabled at the end of server generations, and when VT switching away from
the Xserver.
The implementation details of this may vary on different platforms.
5.4 General bus probe
This is done at the start of the first server generation only.
In the case of ix86 machines, this will be a general PCI probe. The full
information obtained here will be available to the drivers. This information
persists for the life of the Xserver. In the PCI case, the PCI information
for all video cards found is available by calling xf86GetPciVideoInfo().
pciVideoPtr *xf86GetPciVideoInfo(void)
returns a pointer to a list of pointers to pciVideoRec
entries, of which there is one for each detected PCI
video card. The list is terminated with a NULL pointer.
If no PCI video cards were detected, the return value is
NULL.
After the bus probe, the resource broker is initialised.
5.5 Load initial set of modules
This is done at the start of the first server generation only.
The core server contains a list of mandatory modules. These are loaded
first. Currently the only module on this list is the bitmap font module.
The next set of modules loaded are those specified explicitly in the Module
section of the config file.
The final set of initial modules are the driver modules referenced by the
active Device and InputDevice sections in the config file. Each of these
modules is loaded exactly once.
5.6 Register Video and Input Drivers
This is done at the start of the first server generation only.
When a driver module is loaded, the loader calls its Setup function. For
video drivers, this function calls xf86AddDriver() to register the driver's
DriverRec, which contains a small set of essential details and driver entry
points required during the early phase of InitOutput(). xf86AddDriver() adds
it to the global xf86DriverList[] array.
The DriverRec contains the driver canonical name, the Identify(), Probe() and
AvailableOptions() function entry points as well as a pointer to the driver's
module (as returned from the loader when the driver was loaded) and a refer-
ence count which keeps track of how many screens are using the driver. The
entry driver entry points are those required prior to the driver allocating
and filling in its ScrnInfoRec.
For a static server, the xf86DriverList[] array is initialised at build time,
and the loading of modules is not done.
A similar procedure is used for input drivers. The input driver's Setup
function calls xf86AddInputDriver() to register the driver's InputDriverRec,
which contains a small set of essential details and driver entry points
required during the early phase of InitInput(). xf86AddInputDriver() adds it
to the global xf86InputDriverList[] array. For a static server, the
xf86InputDriverList[] array is initialised at build time.
Both the xf86DriverList[] and xf86InputDriverList[] arrays have been ini-
tialised by the end of this stage.
Once all the drivers are registered, their ChipIdentify() functions are
called.
void ChipIdentify(int flags)
This is expected to print a message indicating the driver
name, a short summary of what it supports, and a list of
the chipset names that it supports. It may use the
xf86PrintChipsets() helper to do this.
void xf86PrintChipsets(const char *drvname, const char *drvmsg,
SymTabPtr chips)
This function provides an easy way for a driver's ChipI-
dentify function to format the identification message.
5.7 Initialise Access Control
This is done at the start of the first server generation only.
The Resource Access Control (RAC) subsystem is initialised before calling any
driver functions that may access hardware. All generic bus information is
probed and saved (for restoration later). All (shared resource) video
devices are disabled at the generic bus level, and a probe is done to find
the ``primary'' video device. These devices remain disabled for the next
step.
5.8 Video Driver Probe
This is done at the start of the first server generation only. The Chip-
Probe() function of each registered video driver is called.
Bool ChipProbe(DriverPtr drv, int flags)
The purpose of this is to identify all instances of hard-
ware supported by the driver. The flags value is cur-
rently either 0, PROBE_DEFAULT or PROBE_DETECT.
PROBE_DETECT is used if "-configure" or "-probe" command
line arguments are given and indicates to the Probe()
function that it should not configure the bus entities
and that no XF86Config information is available.
The probe must find the active device sections that match
the driver by calling xf86MatchDevice(). The number of
matches found limits the maximum number of instances for
this driver. If no matches are found, the function
should return FALSE immediately.
Devices that cannot be identified by using device-inde-
pendent methods should be probed at this stage (keeping
in mind that access to all resources that can be disabled
in a device-independent way are disabled during this
phase). The probe must be a minimal probe. It should
just determine if there is a card present that the driver
can drive. It should use the least intrusive probe meth-
ods possible. It must not do anything that is not essen-
tial, like probing for other details such as the amount
of memory installed, etc. It is recommended that the
xf86MatchPciInstances() helper function be used for iden-
tifying matching PCI devices, and similarly the
xf86MatchIsaInstances() for ISA (non-PCI) devices (see
the RAC (section 9., page 1) section). These helpers
also checks and claims the appropriate entity. When not
using the helper, that should be done with xf86CheckPciS-
lot() and xf86ClaimPciSlot() for PCI devices and
xf86ClaimIsaSlot() for ISA devices (see the RAC (section
9., page 1) section).
The probe must register all non-relocatable resources at
this stage. If a resource conflict is found between
exclusive resources the driver will fail immediately.
This is usually best done with the xf86ConfigPciEntity()
helper function for PCI and xf86ConfigIsaEntity() for ISA
(see the RAC (section 9., page 1) section). It is possi-
ble to register some entity specific functions with those
helpers. When not using the helpers, the xf86AddEntity-
ToScreen() xf86ClaimFixedResources() and xf86SetEntity-
Funcs() should be used instead (see the RAC (section 9.,
page 1) section).
If a chipset is specified in an active device section
which the driver considers relevant (ie it has no driver
specified, or the driver specified matches the driver
doing the probe), the Probe must return FALSE if the
chipset doesn't match one supported by the driver.
If there are no active device sections that the driver
considers relevant, it must return FALSE.
Allocate a ScrnInfoRec for each active instance of the
hardware found, and fill in the basic information,
including the other driver entry points. This is best
done with the xf86ConfigIsaEntity() helper function for
ISA instances or xf86ConfigPciEntity() for PCI instances.
These functions allocate a ScrnInfoRec for active enti-
ties. Optionally xf86AllocateScreen() function may also
be used to allocate the ScrnInfoRec. Any of these func-
tions take care of initialising fields to defined
``unused'' values.
Claim the entities for each instance of the hardware
found. This prevents other drivers from claiming the
same hardware.
Must leave hardware in the same state it found it in, and
must not do any hardware initialisation.
All detection can be overridden via the config file, and
that parsed information is available to the driver at
this stage.
Returns TRUE if one or more instances are found, and
FALSE otherwise.
int xf86MatchDevice(const char *drivername,
GDevPtr **driversectlist)
This function takes the name of the driver and returns
via driversectlist a list of device sections that match
the driver name. The function return value is the number
of matches found. If a fatal error is encountered the
return value is -1.
The caller should use xfree() to free *driversectlist
when it is no longer needed.
ScrnInfoPtr xf86AllocateScreen(DriverPtr drv, int flags)
This function allocates a new ScrnInfoRec in the
xf86Screens[] array. This function is normally called by
the video driver ChipProbe() functions. The return value
is a pointer to the newly allocated ScrnInfoRec. The
scrnIndex, origIndex, module and drv fields are ini-
tialised. The reference count in drv is incremented.
The storage for any currently allocated ``privates''
pointers is also allocated and the privates field ini-
tialised (the privates data is of course not allocated or
initialised). This function never returns on failure.
If the allocation fails, the server exits with a fatal
error. The flags value is not currently used, and should
be set to zero.
At the completion of this, a list of ScrnInfoRecs have been allocated in the
xf86Screens[] array, and the associated entities and fixed resources have
been claimed. The following ScrnInfoRec fields must be initialised at this
point:
driverVersion
driverName
scrnIndex(*)
origIndex(*)
drv(*)
module(*)
name
Probe
PreInit
ScreenInit
EnterVT
LeaveVT
numEntities
entityList
access
(*) These are initialised when the ScrnInfoRec is allocated, and not explic-
itly by the driver.
The following ScrnInfoRec fields must be initialised if the driver is going
to use them:
SwitchMode
AdjustFrame
FreeScreen
ValidMode
5.9 Matching Screens
This is done at the start of the first server generation only.
After the Probe phase is finished, there will be some number of ScrnInfoRecs.
These are then matched with the active Screen sections in the XF86Config, and
those not having an active Screen section are deleted. If the number of
remaining screens is 0, InitOutput() sets screenInfo.numScreens to 0 and
returns.
At this point the following fields of the ScrnInfoRecs must be initialised:
confScreen
5.10 Allocate non-conflicting resources
This is done at the start of the first server generation only.
Before calling the drivers again, the resource information collected from the
Probe phase is processed. This includes checking the extent of PCI resources
for the probed devices, and resolving any conflicts in the relocatable PCI
resources. It also reports conflicts, checks bus routing issues, and any-
thing else that is needed to enable the entities for the next phase.
If any drivers registered an EntityInit() function during the Probe phase,
then they are called here.
5.11 Sort the Screens and pre-check Monitor Information
This is done at the start of the first server generation only.
The list of screens is sorted to match the ordering requested in the config
file.
The list of modes for each active monitor is checked against the monitor's
parameters. Invalid modes are pruned.
5.12 PreInit
This is done at the start of the first server generation only.
For each ScrnInfoRec, enable access to the screens entities and call the
ChipPreInit() function.
Bool ChipPreInit(ScrnInfoRec screen, int flags)
The purpose of this function is to find out all the
information required to determine if the configuration is
usable, and to initialise those parts of the ScrnInfoRec
that can be set once at the beginning of the first server
generation.
The number of entities registered for the screen should
be checked against the expected number (most drivers
expect only one). The entity information for each of
them should be retrieved (with xf86GetEntityInfo()) and
checked for the correct bus type and that none of the
sharable resources registered during the Probe phase was
rejected.
Access to resources for the entities that can be con-
trolled in a device-independent way are enabled before
this function is called. If the driver needs to access
any resources that it has disabled in an EntityInit()
function that it registered, then it may enable them here
providing that it disables them before this function
returns.
This includes probing for video memory, clocks, ramdac,
and all other HW info that is needed. It includes deter-
mining the depth/bpp/visual and related info. It
includes validating and determining the set of video
modes that will be used (and anything that is required to
determine that).
This information should be determined in the least intru-
sive way possible. The state of the HW must remain
unchanged by this function. Although video memory
(including MMIO) may be mapped within this function, it
must be unmapped before returning. Driver specific
information should be stored in a structure hooked into
the ScrnInfoRec's driverPrivate field. Any other modules
which require persistent data (ie data that persists
across server generations) should be initialised in this
function, and they should allocate a ``privates'' index
to hook their data into by calling xf86AllocateScrnInfo-
PrivateIndex(). The ``privates'' data is persistent.
Helper functions for some of these things are provided at
the XFree86 common level, and the driver can choose to
make use of them.
All additional resources that the screen needs must be
registered here. This should be done with xf86Register-
Resources(). If some of the fixed resources registered
in the Probe phase are not needed or not decoded by the
hardware when in the OPERATING server state, their status
should be updated with xf86SetOperatingState().
Modules may be loaded at any point in this function, and
all modules that the driver will need must be loaded
before the end of this function. Either the
xf86LoadSubModule() or the xf86LoadDrvSubModule() func-
tion should be used to load modules depending on whether
a ScrnInfoRec has been set up. A driver may unload a mod-
ule within this function if it was only needed temporar-
ily, and the xf86UnloadSubModule() function should be
used to do that. Otherwise there is no need to explic-
itly unload modules because the loader takes care of mod-
ule dependencies and will unload submodules automatically
if/when the driver module is unloaded.
The bulk of the ScrnInfoRec fields should be filled out
in this function.
ChipPreInit() returns FALSE when the configuration is
unusable in some way (unsupported depth, no valid modes,
not enough video memory, etc), and TRUE if it is usable.
It is expected that if the ChipPreInit() function returns
TRUE, then the only reasons that subsequent stages in the
driver might fail are lack or resources (like xalloc
failures). All other possible reasons for failure should
be determined by the ChipPreInit() function.
The ScrnInfoRecs for screens where the ChipPreInit() fails are removed. If
none remain, InitOutput() sets screenInfo.numScreens to 0 and returns.
At this point, further fields of the ScrnInfoRecs would normally be filled
in. Most are not strictly mandatory, but many are required by other layers
and/or helper functions that the driver may choose to use. The documentation
for those layers and helper functions indicates which they require.
The following fields of the ScrnInfoRecs should be filled in if the driver is
going to use them:
monitor
display
depth
pixmapBPP
bitsPerPixel
weight (>8bpp only)
mask (>8bpp only)
offset (>8bpp only)
rgbBits (8bpp only)
gamma
defaultVisual
maxHValue
maxVValue
virtualX
virtualY
displayWidth
frameX0
frameY0
frameX1
frameY1
zoomLocked
modePool
modes
currentMode
progClock (TRUE if clock is programmable)
chipset
ramdac
clockchip
numClocks (if not programmable)
clock[] (if not programmable)
videoRam
biosBase
memBase
memClk
driverPrivate
chipID
chipRev
pointer xf86LoadSubModule(ScrnInfoPtr pScrn, const char *name): and
pointer xf86LoadDrvSubModule(DriverPtr drv, const char *name):
Load a module that a driver depends on. This function
loads the module name as a sub module of the driver. The
return value is a handle identifying the new module. If
the load fails, the return value will be NULL. If a
driver needs to explicitly unload a module it has loaded
in this way, the return value must be saved and passed to
xf86UnloadSubModule() when unloading.
void xf86UnloadSubModule(pointer module)
Unloads the module referenced by module. module should
be a pointer returned previously by xf86LoadSubModule()
or xf86LoadDrvSubModule() .
5.13 Cleaning up Unused Drivers
At this point it is known which screens will be in use, and which drivers are
being used. Unreferenced drivers (and modules they may have loaded) are
unloaded here.
5.14 Consistency Checks
The parameters that must be global to the server, like pixmap formats, bitmap
bit order, bitmap scanline unit and image byte order are compared for each of
the screens. If a mismatch is found, the server exits with an appropriate
message.
5.15 Check if Resource Control is Needed
Determine if resource access control is needed. This is the case if more
than one screen is used. If necessary the RAC wrapper module is loaded.
5.16 AddScreen (ScreenInit)
At this point, the valid screens are known. AddScreen() is called for each
of them, passing ChipScreenInit() as the argument. AddScreen() is a DIX
function that allocates a new screenInfo.screen[] entry (aka pScreen), and
does some basic initialisation of it. It then calls the ChipScreenInit()
function, with pScreen as one of its arguments. If ChipScreenInit() returns
FALSE, AddScreen() returns -1. Otherwise it returns the index of the screen.
AddScreen() should only fail because of programming errors or failure to
allocate resources (like memory). All configuration problems should be
detected BEFORE this point.
Bool ChipScreenInit(int index, ScreenPtr pScreen,
int argc, char **argv)
This is called at the start of each server generation.
Fill in all of pScreen, possibly doing some of this by
calling ScreenInit functions from other layers like mi,
framebuffers (cfb, etc), and extensions.
Decide which operations need to be placed under resource
access control. The classes of operations are the frame
buffer operations (RAC_FB), the pointer operations
(RAC_CURSOR), the viewport change operations (RAC_VIEW-
PORT) and the colormap operations (RAC_COLORMAP). Any
operation that requires resources which might be disabled
during OPERATING state should be set to use RAC. This
can be specified separately for memory and IO resources
(the racMemFlags and racIoFlags fields of the ScrnInfoRec
respectively).
Map any video memory or other memory regions.
Save the video card state. Enough state must be saved so
that the original state can later be restored.
Initialise the initial video mode. The ScrnInfoRec's
vtSema field should be set to TRUE just prior to changing
the video hardware's state.
The ChipScreenInit() function (or functions from other layers that it calls)
should allocate entries in the ScreenRec's devPrivates area by calling Allo-
cateScreenPrivateIndex() if it needs per-generation storage. Since the
ScreenRec's devPrivates information is cleared for each server generation,
this is the correct place to initialise it.
After AddScreen() has successfully returned, the following ScrnInfoRec fields
are initialised:
pScreen
racMemFlags
racIoFlags
The ChipScreenInit() function should initialise the CloseScreen and Save-
Screen fields of pScreen. The old value of pScreen->CloseScreen should be
saved as part of the driver's per-screen private data, allowing it to be
called from ChipCloseScreen(). This means that the existing CloseScreen()
function is wrapped.
5.17 Finalising RAC Initialisation
After all the ChipScreenInit() functions have been called, each screen has
registered its RAC requirements. This information is used to determine which
shared resources are requested by more than one driver and set the access
functions accordingly. This is done following these rules:
1. The sharable resources registered by each entity are compared. If a
resource is registered by more than one entity the entity will be
marked to indicate that it needs to share this resources type (IO or
MEM).
2. A resource marked ``disabled'' during OPERATING state will be ignored
entirely.
3. A resource marked ``unused'' will only conflict with an overlapping
resource of an other entity if the second is actually in use during
OPERATING state.
4. If an ``unused'' resource was found to conflict but the entity does not
use any other resource of this type the entire resource type will be
disabled for that entity.
5.18 Finishing InitOutput()
At this point InitOutput() is finished, and all the screens have been setup
in their initial video mode.
5.19 Mode Switching
When a SwitchMode event is received, ChipSwitchMode() is called (when it
exists):
Bool ChipSwitchMode(int index, DisplayModePtr mode, int flags)
Initialises the new mode for the screen identified by
index;. The viewport may need to be adjusted also.
5.20 Changing Viewport
When a Change Viewport event is received, ChipAdjustFrame() is called (when
it exists):
void ChipAdjustFrame(int index, int x, int y, int flags)
Changes the viewport for the screen identified by index;.
It should be noted that many chipsets impose restrictions
on where the viewport may be placed in the virtual reso-
lution, either for alignment reasons, or to prevent the
start of the viewport from being positioned within a
pixel (as can happen in a 24bpp mode). After calculating
the value the chipset's panning registers need to be set
to for non-DGA modes, this function should recalculate
the ScrnInfoRec's frameX0, frameY0, frameX1 and frameY1
fields to correspond to that value. If this is not done,
switching to another mode might cause the position of a
hardware cursor to change.
5.21 VT Switching
When a VT switch event is received, xf86VTSwitch() is called. xf86VTSwitch()
does the following:
On ENTER:
o enable port I/O access
o save and initialise the bus/resource state
o enter the SETUP server state
o calls ChipEnterVT() for each screen
o enter the OPERATING server state
o validate GCs
o Restore fb from saved pixmap for each screen
o Enable all input devices
On LEAVE:
o Save fb to pixmap for each screen
o validate GCs
o enter the SETUP server state
o calls ChipLeaveVT() for each screen
o disable all input devices
o restore bus/resource state
o disables port I/O access
Bool ChipEnterVT(int index, int flags)
This function should initialise the current video mode
and initialise the viewport, turn on the HW cursor if
appropriate, etc.
Should it re-save the video state before initialising the
video mode?
void ChipLeaveVT(int index, int flags)
This function should restore the saved video state. If
appropriate it should also turn off the HW cursor, and
invalidate any pixmap/font caches.
Optionally, ChipLeaveVT() may also unmap memory regions. If so,
ChipEnterVT() will need to remap them. Additionally, if an aper-
ture used to access video memory is unmapped and remapped in this
fashion, ChipEnterVT() will also need to notify the framebuffer
layers of the aperture's new location in virtual memory. This is
done with a call to the screen's ModifyPixmapHeader() function, as
follows
(*pScreen->ModifyPixmapHeader)(pScrn->ppix,
-1, -1, -1, -1, -1, NewApertureAddress);
where the ``ppix'' field in a ScrnInfoRec
points to the pixmap used by the screen's
SaveRestoreImage() function to hold the
screen's contents while switched out.
Currently, aperture remapping, as described here, should not be
attempted if the driver uses the xf8_16bpp or xf8_32bpp framebuffer
layers. A pending restructuring of VT switching will address this
restriction in the near future.
Other layers may wrap the ChipEnterVT() and ChipLeaveVT() functions if they
need to take some action when these events are received.
5.22 End of server generation
At the end of each server generation, the DIX layer calls ChipCloseScreen()
for each screen:
Bool ChipCloseScreen(int index, ScreenPtr pScreen)
This function should restore the saved video state and
unmap the memory regions.
It should also free per-screen data structures allocated
by the driver. Note that the persistent data held in the
ScrnInfoRec's driverPrivate field should not be freed
here because it is needed by subsequent server genera-
tions.
The ScrnInfoRec's vtSema field should be set to FALSE
once the video HW state has been restored.
Before freeing the per-screen driver data the saved Clos-
eScreen value should be restored to pScreen->CloseScreen,
and that function should be called after freeing the
data.
6. Optional Driver Functions
The functions outlined here can be called from the XFree86 common layer, but
their presence is optional.
6.1 Mode Validation
When a mode validation helper supplied by the XFree86-common layer is being
used, it can be useful to provide a function to check for hw specific mode
constraints:
ModeStatus ChipValidMode(int index, DisplayModePtr mode,
Bool verbose, int flags)
Check the passed mode for hw-specific constraints, and
return the appropriate status value.
This function may also modify the effective timings and clock of the passed
mode. These have been stored in the mode's Crtc* and SynthClock elements,
and have already been adjusted for interlacing, doublescanning, multiscanning
and clock multipliers and dividers. The function should not modify any other
mode field, unless it wants to modify the mode timings reported to the user
by xf86PrintModes().
The function is called once for every mode in the XF86Config Monitor section
assigned to the screen, with flags set to MODECHECK_INITIAL. It is subse-
quently called for every mode in the XF86Config Display subsection assigned
to the screen, with flags set to MODECHECK_FINAL. In the second case, the
mode will have successfully passed all other tests. In addition, the ScrnIn-
foRec's virtualX, virtualY and displayWidth fields will have been set as if
the mode to be validated were to be the last mode accepted.
In effect, calls with MODECHECK_INITIAL are intended for checks that do not
depend on any mode other than the one being validated, while calls with MOD-
ECHECK_FINAL are intended for checks that may involve more than one mode.
6.2 Free screen data
When a screen is deleted prior to the completion of the ScreenInit phase the
ChipFreeScreen() function is called when defined.
void ChipFreeScreen(int scrnindex, int flags)
Free any driver-allocated data that may have been allo-
cated up to and including an unsuccessful Chip-
ScreenInit() call. This would predominantly be data
allocated by ChipPreInit() that persists across server
generations. It would include the driverPrivate, and any
``privates'' entries that modules may have allocated.
7. Recommended driver functions
The functions outlined here are for internal use by the driver only. They
are entirely optional, and are never accessed directly from higher layers.
The sample function declarations shown here are just examples. The interface
(if any) used is up to the driver.
7.1 Save
Save the video state. This could be called from ChipScreenInit() and (possi-
bly) ChipEnterVT().
void ChipSave(ScrnInfoPtr pScrn)
Saves the current state. This will only be saving pre-
server states or states before returning to the server.
There is only one current saved state per screen and it
is stored in private storage in the screen.
7.2 Restore
Restore the original video state. This could be called from the
ChipLeaveVT() and ChipCloseScreen() functions.
void ChipRestore(ScrnInfoPtr pScrn)
Restores the saved state from the private storage. Usu-
ally only used for restoring text modes.
7.3 Initialise Mode
Initialise a video mode. This could be called from the ChipScreenInit(),
ChipSwitchMode() and ChipEnterVT() functions.
Bool ChipModeInit(ScrnInfoPtr pScrn, DisplayModePtr mode)
Programs the hardware for the given video mode.
8. Data and Data Structures
8.1 Command line data
Command line options are typically global, and are stored in global vari-
ables. These variables are read-only and are available to drivers via a
function call interface. Most of these command line values are processed via
helper functions to ensure that they are treated consistently by all drivers.
The other means of access is provided for cases where the supplied helper
functions might not be appropriate.
Some of them are:
xf86Verbose verbosity level
xf86Bpp -bpp from the command line
xf86Depth -depth from the command line
xf86Weight -weight from the command line
xf86Gamma -{r,g,b,}gamma from the command line
xf86FlipPixels -flippixels from the command line
xf86ProbeOnly -probeonly from the command line
defaultColorVisualClass -cc from the command line
If we ever do allow for screen-specific command line options, we may need to
rethink this.
These can be accessed in a read-only manner by drivers with the following
functions:
int xf86GetVerbosity()
Returns the value of xf86Verbose.
int xf86GetDepth()
Returns the -depth command line setting. If not set on
the command line, -1 is returned.
rgb xf86GetWeight()
Returns the -weight command line setting. If not set on
the command line, {0, 0, 0} is returned.
Gamma xf86GetGamma()
Returns the -gamma or -rgamma, -ggamma, -bgamma command
line settings. If not set on the command line, {0.0,
0.0, 0.0} is returned.
Bool xf86GetFlipPixels()
Returns TRUE if -flippixels is present on the command
line, and FALSE otherwise.
const char *xf86GetServerName()
Returns the name of the X server from the command line.
8.2 Data handling
Config file data contains parts that are global, and parts that are Screen
specific. All of it is parsed into data structures that neither the drivers
or most other parts of the server need to know about.
The global data is typically not required by drivers, and as such, most of it
is stored in the private xf86InfoRec.
The screen-specific data collected from the config file is stored in screen,
device, display, monitor-specific data structures that are separate from the
ScrnInfoRecs, with the appropriate elements/fields hooked into the ScrnIn-
foRecs as required. The screen config data is held in confScreenRec, device
data in the GDevRec, monitor data in the MonRec, and display data in the Dis-
pRec.
The XFree86 common layer's screen specific data (the actual data in use for
each screen) is held in the ScrnInfoRecs. As has been outlined above, the
ScrnInfoRecs are allocated at probe time, and it is the responsibility of the
Drivers' Probe() and PreInit() functions to finish filling them in based on
both data provided on the command line and data provided from the Config
file. The precedence for this is:
command line -> config file -> probed/default data
For most things in this category there are helper functions that the drivers
can use to ensure that the above precedence is consistently used.
As well as containing screen-specific data that the XFree86 common layer
(including essential parts of the server infrastructure as well as helper
functions) needs to access, it also contains some data that drivers use
internally. When considering whether to add a new field to the ScrnInfoRec,
consider the balance between the convenience of things that lots of drivers
need and the size/obscurity of the ScrnInfoRec.
Per-screen driver specific data that cannot be accommodated with the static
ScrnInfoRec fields is held in a driver-defined data structure, a pointer to
which is assigned to the ScrnInfoRec's driverPrivate field. This is per-
screen data that persists across server generations (as does the bulk of the
static ScrnInfoRec data). It would typically also include the video card's
saved state.
Per-screen data for other modules that the driver uses (for example, the XAA
module) that is reset for each server generation is hooked into the ScrnIn-
foRec through it's privates field.
Once it has stabilised, the data structures and variables accessible to video
drivers will be documented here. In the meantime, those things defined in
the xf86.h and xf86str.h files are visible to video drivers. Things defined
in xf86Priv.h and xf86Privstr.h are NOT intended to be visible to video
drivers, and it is an error for a driver to include those files.
8.3 Accessing global data
Some other global state information that the drivers may access via functions
is as follows:
Bool xf86ServerIsExiting()
Returns TRUE if the server is at the end of a generation
and is in the process of exiting, and FALSE otherwise.
Bool xf86ServerIsResetting()
Returns TRUE if the server is at the end of a generation
and is in the process of resetting, and FALSE otherwise.
Bool xf86ServerIsInitialising()
Returns TRUE if the server is at the beginning of a gen-
eration and is in the process of initialising, and FALSE
otherwise.
Bool xf86ServerIsOnlyProbing()
Returns TRUE if the -probeonly command line flag was
specified, and FALSE otherwise.
Bool xf86CaughtSignal()
Returns TRUE if the server has caught a signal, and FALSE
otherwise.
8.4 Allocating private data
A driver and any module it uses may allocate per-screen private storage in
either the ScreenRec (DIX level) or ScrnInfoRec (XFree86 common layer level).
ScreenRec storage persists only for a single server generation, and ScrnIn-
foRec storage persists across generations for the lifetime of the server.
The ScreenRec devPrivates data must be reallocated/initialised at the start
of each new generation. This is normally done from the ChipScreenInit()
function, and Init functions for other modules that it calls. Data allocated
in this way should be freed by the driver's ChipCloseScreen() functions, and
Close functions for other modules that it calls. A new devPrivates entry is
allocated by calling the AllocateScreenPrivateIndex() function.
int AllocateScreenPrivateIndex()
This function allocates a new element in the devPrivates
field of all currently existing ScreenRecs. The return
value is the index of this new element in the devPrivates
array. The devPrivates field is of type DevUnion:
typedef union _DevUnion {
pointer ptr;
long val;
unsigned long uval;
pointer (*fptr)(void);
} DevUnion;
which allows the element to be used for any of the above
types. It is commonly used as a pointer to data that the
caller allocates after the new index has been allocated.
This function will return -1 when there is an error allo-
cating the new index.
The ScrnInfoRec privates data persists for the life of the server, so only
needs to be allocated once. This should be done from the ChipPreInit() func-
tion, and Init functions for other modules that it calls. Data allocated in
this way should be freed by the driver's ChipFreeScreen() functions, and Free
functions for other modules that it calls. A new privates entry is allocated
by calling the xf86AllocateScrnInfoPrivateIndex() function.
int xf86AllocateScrnInfoPrivateIndex()
This function allocates a new element in the privates
field of all currently existing ScrnInfoRecs. The return
value is the index of this new element in the privates
array. The privates field is of type DevUnion:
typedef union _DevUnion {
pointer ptr;
long val;
unsigned long uval;
pointer (*fptr)(void);
} DevUnion;
which allows the element to be used for any of the above
types. It is commonly used as a pointer to data that the
caller allocates after the new index has been allocated.
This function will not return when there is an error
allocating the new index. When there is an error it will
cause the server to exit with a fatal error. The similar
function for allocation privates in the ScreenRec (Allo-
cateScreenPrivateIndex()) differs in this respect by
returning -1 when the allocation fails.
9. Keeping Track of Bus Resources
9.1 Theory of Operation
The XFree86 common layer has knowledge of generic access control mechanisms
for devices on certain bus systems (currently the PCI bus) as well as of
methods to enable or disable access to the buses itself. Furthermore it can
access information on resources decoded by these devices and if necessary
modify it.
When first starting the Xserver collects all this information, saves it for
restoration, checks it for consistency, and if necessary, corrects it.
Finally it disables all resources on a generic level prior to calling any
driver function.
When the Probe() function of each driver is called the device sections are
matched against the devices found in the system. The driver may probe
devices at this stage that cannot be identified by using device independent
methods. Access to all resources that can be controlled in a device indepen-
dent way is disabled. The Probe() function should register all non-relocat-
able resources at this stage. If a resource conflict is found between exclu-
sive resources the driver will fail immediately. Optionally the driver might
specify an EntityInit(), EntityLeave() and EntityEnter() function.
EntityInit() can be used to disable any shared resources that are not con-
trolled by the generic access control functions. It is called prior to the
PreInit phase regardless if an entity is active or not. When calling the
EntityInit(), EntityEnter() and EntityLeave() functions the common level will
disable access to all other entities on a generic level. Since the common
level has no knowledge of device specific methods to disable access to
resources it cannot be guaranteed that certain resources are not decoded by
any other entity until the EntityInit() or EntityEnter() phase is finished.
Device drivers should therefore register all those resources which they are
going to disable. If these resources are never to be used by any driver
function they may be flagged ResInit so that they can be removed from the
resource list after processing all EntityInit() functions. EntityEnter()
should disable decoding of all resources which are not registered as exclu-
sive and which are not handled by the generic access control in the common
level. The difference to EntityInit() is that the latter one is only called
once during lifetime of the server. It can therefore be used to set up vari-
ables prior to disabling resources. EntityLeave() should restore the origi-
nal state when exiting the server or switching to a different VT. It also
needs to disable device specific access functions if they need to be disabled
on server exit or VT switch. The default state is to enable them before giv-
ing up the VT.
In PreInit() phase each driver should check if any sharable resources it has
registered during Probe() has been denied and take appropriate action which
could simply be to fail. If it needs to access resources it has disabled
during EntitySetup() it can do so provided it has registered these and will
disable them before returning from PreInit(). This also applies to all other
driver functions. Several functions are provided to request resource ranges,
register these, correct PCI config space and add replacements for the generic
access functions. Resources may be marked ``disabled'' or ``unused'' during
OPERATING stage. Although these steps could also be performed in
ScreenInit(), this is not desirable.
Following PreInit() phase the common level determines if resource access con-
trol is needed. This is the case if more than one screen is used. If neces-
sary the RAC wrapper module is loaded. In ScreenInit() the drivers can
decide which operations need to be placed under RAC. Available are the frame
buffer operations, the pointer operations and the colormap operations. Any
operation that requires resources which might be disabled during OPERATING
state should be set to use RAC. This can be specified separately for memory
and IO resources.
When ScreenInit() phase is done the common level will determine which shared
resources are requested by more than one driver and set the access functions
accordingly. This is done following these rules:
1. The sharable resources registered by each entity are compared. If a
resource is registered by more than one entity the entity will be
marked to need to share this resources type (IO or MEM).
2. A resource marked ``disabled'' during OPERATING state will be ignored
entirely.
3. A resource marked ``unused'' will only conflicts with an overlapping
resource of an other entity if the second is actually in use during
OPERATING state.
4. If an ``unused'' resource was found to conflict however the entity does
not use any other resource of this type the entire resource type will
be disabled for that entity.
The driver has the choice among different ways to control access to certain
resources:
1. It can rely on the generic access functions. This is probably the most
common case. Here the driver only needs to register any resource it is
going to use.
2. It can replace the generic access functions by driver specific ones.
This will mostly be used in cases where no generic access functions are
available. In this case the driver has to make sure these resources
are disabled when entering the PreInit() stage. Since the replacement
functions are registered in PreInit() the driver will have to enable
these resources itself if it needs to access them during this state.
The driver can specify if the replacement functions can control memory
and/or I/O resources separately.
3. The driver can enable resources itself when it needs them. Each driver
function enabling them needs to disable them before it will return.
This should be used if a resource which can be controlled in a device
dependent way is only required during SETUP state. This way it can be
marked ``unused'' during OPERATING state.
A resource which is decoded during OPERATING state however never accessed by
the driver should be marked unused.
Since access switching latencies are an issue during Xserver operation, the
common level attempts to minimize the number of entities that need to be
placed under RAC control. When a wrapped operation is called, the EnableAc-
cess() function is called before control is passed on. EnableAccess() checks
if a screen is under access control. If not it just establishes bus routing
and returns. If the screen needs to be under access control, EnableAccess()
determines which resource types (MEM, IO) are required. Then it tests if
this access is already established. If so it simply returns. If not it dis-
ables the currently established access, fixes bus routing and enables access
to all entities registered for this screen.
Whenever a mode switch or a VT-switch is performed the common level will
return to SETUP state.
9.2 Resource Types
Resource have certain properties. When registering resources each range is
accompanied by a flag consisting of the ORed flags of the different proper-
ties the resource has. Each resource range may be classified according to
o its physical properties i.e., if it addresses memory (ResMem) or I/O
space (ResIo),
o if it addresses a block (ResBlock) or sparse (ResSparse) range,
o its access properties.
There are two known access properties:
o ResExclusive for resources which may not be shared with any other device
and
o ResShared for resources which can be disabled and therefore can be
shared.
If it is necessary to test a resource against any type a generic access type
ResAny is provided. If this is set the resource will conflict with any
resource of a different entity intersecting its range. Further it can be
specified that a resource is decoded however never used during any stage
(ResUnused) or during OPERATING state (ResUnusedOpr). A resource only visi-
ble during the init functions (ie. EntityInit(), EntityEnter() and
EntityLeave() should be registered with the flag ResInit. A resource that
might conflict with background resource ranges may be flagged with ResBios.
This might be useful when registering resources ranges that were assigned by
the system Bios.
Several predefined resource lists are available for VGA and 8514/A resources
in common/xf86Resources.h.
9.3 Available Functions
The functions provided for resource management are listed in their order of
use in the driver.
9.3.1 Probe Phase
In this phase each driver detects those resources it is able to drive, cre-
ates an entity record for each of them, registers non-relocatable resources
and allocates screens and adds the resources to screens.
Two helper functions are provided for matching device sections in the
XF86Config file to the devices:
int xf86MatchPciInstances(const char *driverName, int vendorID,
SymTabPtr chipsets, PciChipsets *PCIchipsets,
GDevPtr *devList, int numDevs, DriverPtr drvp,
int **foundEntities)
This function finds matches between PCI cards that a
driver supports and config file device sections. It is
intended for use in the ChipProbe() function of drivers
for PCI cards. Only probed PCI devices with a vendor ID
matching vendorID are considered. devList and numDevs
are typically those found from calling xf86MatchDevice(),
and represent the active config file device sections rel-
evant to the driver. PCIchipsets is a table that pro-
vides a mapping between the PCI device IDs, the driver's
internal chipset tokens and a list of fixed resources.
When a device section doesn't have a BusID entry it can
only match the primary video device. Secondary devices
are only matched with device sections that have a match-
ing BusID entry.
Once the preliminary matches have been found, a final
match is confirmed by checking if the chipset override,
ChipID override or probed PCI chipset type match one of
those given in the chipsets and PCIchipsets lists. The
PCIchipsets list includes a list of the PCI device IDs
supported by the driver. The list should be terminated
with an entry with PCI ID -1". The chipsets list is a
table mapping the driver's internal chipset tokens to
names, and should be terminated with a NULL entry. Only
those entries with a corresponding entry in the PCI-
chipsets list are considered. The order of precedence
is: config file chipset, config file ChipID, probed PCI
device ID.
In cases where a driver handles PCI chipsets with more
than one vendor ID, it may set vendorID to 0, and OR each
devID in the list with (the vendor ID << 16).
Entity index numbers for confirmed matches are returned
as an array via foundEntities. The PCI information,
chipset token and device section for each match are found
in the EntityInfoRec referenced by the indices.
The function return value is the number of confirmed
matches. A return value of -1 indicates an internal
error. The returned foundEntities array should be freed
by the driver with xfree() when it is no longer needed in
cases where the return value is greater than zero.
int xf86MatchIsaInstances(const char *driverName,
SymTabPtr chipsets, IsaChipsets *ISAchipsets,
DriverPtr drvp, FindIsaDevProc FindIsaDevice,
GDevPtr *devList, int numDevs, int **foundEntities)
This function finds matches between ISA cards that a
driver supports and config file device sections. It is
intended for use in the ChipProbe() function of drivers
for ISA cards. devList and numDevs are typically those
found from calling xf86MatchDevice(), and represent the
active config file device sections relevant to the
driver. ISAchipsets is a table that provides a mapping
between the driver's internal chipset tokens and the
resource classes. FindIsaDevice is a driver-provided
function that probes the hardware and returns the chipset
token corresponding to what was detected, and -1 if noth-
ing was detected.
If the config file device section contains a chipset
entry, then it is checked against the chipsets list.
When no chipset entry is present, the FindIsaDevice func-
tion is called instead.
Entity index numbers for confirmed matches are returned
as an array via foundEntities. The chipset token and
device section for each match are found in the EntityIn-
foRec referenced by the indices.
The function return value is the number of confirmed
matches. A return value of -1 indicates an internal
error. The returned foundEntities array should be freed
by the driver with xfree() when it is no longer needed in
cases where the return value is greater than zero.
These two helper functions make use of several core functions that are avail-
able at the driver level:
Bool xf86ParsePciBusString(const char *busID, int *bus,
int *device, int *func)
Takes a BusID string, and if it is in the correct format,
returns the PCI bus, device, func values that it indi-
cates. The format of the string is expected to be
"PCI:bus:device:func" where each of `bus', `device' and
`func' are decimal integers. The ":func" part may be
omitted, and the func value assumed to be zero, but this
isn't encouraged. The "PCI" prefix may also be omitted.
The prefix "AGP" is currently equivalent to the "PCI"
prefix. If the string isn't a valid PCI BusID, the
return value is FALSE.
Bool xf86ComparePciBusString(const char *busID, int bus,
int device, int func)
Compares a BusID string with PCI bus, device, func val-
ues. If they match TRUE is returned, and FALSE if they
don't.
Bool xf86ParseIsaBusString(const char *busID)
Compares a BusID string with the ISA bus ID string ("ISA"
or "ISA:"). If they match TRUE is returned, and FALSE if
they don't.
Bool xf86CheckPciSlot(int bus, int device, int func)
Checks if the PCI slot bus:device:func has been claimed.
If so, it returns FALSE, and otherwise TRUE.
int xf86ClaimPciSlot(int bus, int device, int func, DriverPtr drvp,
int chipset, GDevPtr dev, Bool active)
This function is used to claim a PCI slot, allocate the
associated entity record and initialise their data struc-
tures. The return value is the index of the newly allo-
cated entity record, or -1 if the claim fails. This
function should always succeed if xf86CheckPciSlot()
returned TRUE for the same PCI slot.
Bool xf86IsPrimaryPci(void)
This function returns TRUE if the primary card is a PCI
device, and FALSE otherwise.
int xf86ClaimIsaSlot(DriverPtr drvp, int chipset,
GDevPtr dev, Bool active)
This allocates an entity record entity and initialise the
data structures. The return value is the index of the
newly allocated entity record.
Bool xf86IsPrimaryIsa(void)
This function returns TRUE if the primary card is an ISA
(non-PCI) device, and FALSE otherwise.
Two helper functions are provided to aid configuring entities:
ScrnInfoPtr xf86ConfigPciEntity(ScrnInfoPtr pScrn,
int scrnFlag, int entityIndex,
PciChipsets *p_chip,
resList res, EntityProc init,
EntityProc enter, EntityProc leave,
pointer private)
ScrnInfoPtr xf86ConfigIsaEntity(ScrnInfoPtr pScrn,
int scrnFlag, int entityIndex,
IsaChipsets *i_chip,
resList res, EntityProc init,
EntityProc enter, EntityProc leave,
pointer private)
These functions are used to register the non-relocatable
resources for an entity, and the optional entity-specific
Init, Enter and Leave functions. Usually the list of
fixed resources is obtained from the Isa/PciChipsets
lists. However an additional list of resources may be
passed. Generally this is not required. For active
entities a ScrnInfoRec is allocated if the pScrn argument
is NULL. The return value is TRUE when successful. The
init, enter, leave functions are defined as follows:
typedef void (*EntityProc)(int entityIndex,
pointer private)
They are passed the entity index and a pointer to a pri-
vate scratch area. This can be set up during Probe() and
its address can be passed to xf86ConfigIsaEntity() and
xf86ConfigPciEntity() as the last argument.
These two helper functions make use of several core functions that are avail-
able at the driver level:
void xf86ClaimFixedResources(resList list, int entityIndex)
This function registers the non-relocatable resources
which cannot be disabled and which therefore would cause
the server to fail immediately if they were found to con-
flict. It also records non-relocatable but sharable
resources for processing after the Probe() phase.
Bool xf86SetEntityFuncs(int entityIndex, EntityProc init,
EntityProc enter, EntityProc leave, pointer)
This function registers with an entity the init, enter,
leave functions along with the pointer to their private
area.
void xf86AddEntityToScreen(ScrnInfoPtr pScrn, int entityIndex)
This function associates the entity referenced by enti-
tyIndex with the screen.
9.3.2 PreInit Phase
During this phase the remaining resources should be registered. PreInit()
should call xf86GetEntityInfo() to obtain a pointer to an EntityInfoRec for
each entity it is able to drive and check if any resource are listed in its
resources field. If resources registered in the Probe phase have been
rejected in the post-Probe phase (resources is non-NULL), then the driver
should decide if it can continue without using these or if it should fail.
EntityInfoPtr xf86GetEntityInfo(int entityIndex)
This function returns a pointer to the EntityInfoRec ref-
erenced by entityIndex. The returned EntityInfoRec
should be freed with xfree() when no longer needed.
Several functions are provided to simplify resource registration:
Bool xf86IsEntityPrimary(int entityIndex)
This function returns TRUE if the entity referenced by
entityIndex is the primary display device (i.e., the one
initialised at boot time and used in text mode).
Bool xf86IsScreenPrimary(int scrnIndex)
This function returns TRUE if the primary entity is reg-
istered with the screen referenced by scrnIndex.
pciVideoPtr xf86GetPciInfoForEntity(int entityIndex)
This function returns a pointer to the pciVideoRec for
the specified entity. If the entity is not a PCI device,
NULL is returned.
The primary function for registration of resources is:
resPtr xf86RegisterResources(int entityIndex, resList list,
int access)
This function tries to register the resources in list.
If list is NULL it tries to determine the resources auto-
matically. This only works for entities that provide a
generic way to read out the resource ranges they decode.
So far this is only the case for PCI devices. By default
the PCI resources are registered as shared (ResShared) if
the driver wants to set a different access type it can do
so by specifying the access flags in the third argument.
A value of 0 means to use the default settings. If for
any reason the resource broker is not able to register
some of the requested resources the function will return
a pointer to a list of the failed ones. In this case the
driver may be able to move the resource to different
locations. In case of PCI bus entities this is done by
passing the list of failed resources to xf86ReallocateP-
ciResources(). When the registration succeeds, the
return value is NULL.
resPtr xf86ReallocatePciResources(int entityIndex, resPtr pRes)
This function takes a list of PCI resources that need to
be reallocated and returns NULL when all relocations are
successful. xf86RegisterResources() should be called
again to register the relocated resources with the bro-
ker. If the reallocation fails, a list of the resources
that could not be relocated is returned.
Two functions are provided to obtain a resource range of a given type:
resRange xf86GetBlock(long type, memType size,
memType window_start, memType window_end,
memType align_mask, resPtr avoid)
This function tries to find a block range of size size
and type type in a window bound by window_start and win-
dow_end with the alignment specified in align_mask.
Optionally a list of resource ranges which should be
avoided within the window can be supplied. On failure a
zero-length range of type ResEnd will be returned.
resRange xf86GetSparse(long type, memType fixed_bits,
memType decode_mask, memType address_mask,
resPtr avoid)
This function is like the previous one, but attempts to
find a sparse range instead of a block range. Here three
values have to be specified: the address_mask which marks
all bits of the mask part of the address, the decode_mask
which masks out the bits which are hardcoded and are
therefore not available for relocation and the values of
the fixed bits. The function tries to find a base that
satisfies the given condition. If the function fails it
will return a zero range of type ResEnd. Optionally it
might be passed a list of resource ranges to avoid.
Some PCI devices are broken in the sense that they return invalid size infor-
mation for a certain resource. In this case the driver can supply the cor-
rect size and make sure that the resource range allocated for the card is
large enough to hold the address range decoded by the card. The function
xf86FixPciResource() can be used to do this:
Bool xf86FixPciResource(int entityIndex, unsigned int prt,
CARD32 alignment, long type)
This function fixes a PCI resource allocation. The prt
parameter contains the number of the PCI base register
that needs to be fixed (0-5, and 6 for the BIOS base reg-
ister). The size is specified by the alignment. Since
PCI resources need to span an integral range of size 2^n,
the alignment also specifies the number of addresses that
will be decoded. If the driver specifies a type mask it
can override the default type for PCI resources which is
ResShared. The resource broker needs to know that to
find a matching resource range. This function should be
called before calling xf86RegisterResources(). The
return value is TRUE when the function succeeds.
Bool xf86CheckPciMemBase(pciVideoPtr pPci, memType base)
This function checks that the memory base address speci-
fied matches one of the PCI base address register values
for the given PCI device. This is mostly used to check
that an externally provided base address (e.g., from a
config file) matches an actual value allocated to a
device.
The driver may replace the generic access control functions for an entity.
This is done with the xf86SetAccessFuncs():
void xf86SetAccessFuncs(EntityInfoPtr pEnt,
xf86SetAccessFuncPtr funcs,
xf86SetAccessFuncPtr oldFuncs)
with:
typedef struct {
xf86AccessPtr mem;
xf86AccessPtr io;
xf86AccessPtr io_mem;
} xf86SetAccessFuncRec, *xf86SetAccessFuncPtr;
The driver can pass three functions: one for I/O access,
one for memory access and one for combined memory and I/O
access. If the memory access and combined access func-
tions are identical the common level assumes that the
memory access cannot be controlled independently of I/O
access, if the I/O access function and the combined
access functions are the same it is assumed that I/O can
not be controlled independently. If memory and I/O have
to be controlled together all three values should be the
same. If a non NULL value is passed as third argument it
is interpreted as an address where to store the old
access record. If the third argument is NULL it will be
assumed that the generic access should be enabled before
replacing the access functions. Otherwise it will be
disabled. The driver may enable them itself using the
returned values. It should do this from its replacement
access functions as the generic access may be disabled by
the common level on certain occasions. If replacement
functions are specified they must control all resources
of the specific type registered for the entity.
To find out if a specific resource range conflicts with another resource the
xf86ChkConflict() function may be used:
memType xf86ChkConflict(resRange *rgp, int entityIndex)
This function checks if the resource range rgp of for the
specified entity conflicts with with another resource.
If a conflict is found, the address of the start of the
conflict is returned. The return value is zero when
there is no conflict.
The OPERATING state properties of previously registered fixed resources can
be set with the xf86SetOperatingState() function:
resPtr xf86SetOperatingState(resList list, int entityIndex,
int mask)
This function is used to set the status of a resource
during OPERATING state. list holds a list to which mask
is to be applied. The parameter mask may have the value
ResUnusedOpr and ResDisableOpr. The first one should be
used if a resource isn't used by the driver during OPER-
ATING state although it is decoded by the device, while
the latter one indicates that the resource is not decoded
during OPERATING state. Note that the resource ranges
have to match those specified during registration. If a
range has been specified starting at A and ending at B
and suppose C us a value satisfying A < C < B one may not
specify the resource range (A,B) by splitting it into two
ranges (A,C) and (C,B).
The following two functions are provided for special cases:
void xf86RemoveEntityFromScreen(ScrnInfoPtr pScrn, int entityIndex)
This function may be used to remove an entity from a
screen. This only makes sense if a screen has more than
one entity assigned or the screen is to be deleted. No
test is made if the screen has any entities left.
void xf86DeallocateResourcesForEntity(int entityIndex, long type)
This function deallocates all resources of a given type
registered for a certain entity from the resource broker
list.
9.3.3 ScreenInit Phase
All that is required in this phase is to setup the RAC flags. Note that it
is also permissible to set these flags up in the PreInit phase. The RAC
flags are held in the racIoFlags and racMemFlags fields of the ScrnInfoRec
for each screen. They specify which graphics operations might require the
use of shared resources. This can be specified separately for memory and I/O
resources. The available flags are defined in rac/xf86RAC.h. They are:
RAC_FB
for framebuffer operations (including hw acceleration)
RAC_CURSOR
for Cursor operations (??? I'm not sure if we need this for SW cur-
sor it depends on which level the sw cursor is drawn)
RAC_COLORMAP
for colormap operations
RAC_VIEWPORT
for the call to ChipAdjustFrame()
The flags are ORed together.
10. Config file ``Option'' entries
Option entries are permitted in most sections and subsections of the config
file. There are two forms of option entries:
Option "option-name"
A boolean option.
Option "option-name" "option-value"
An option with an arbitrary value.
The option entries are handled by the parser, and a list of the parsed
options is included with each of the appropriate data structures that the
drivers have access to. The data structures used to hold the option informa-
tion are opaque to the driver, and a driver must not access the option data
directly. Instead, the common layer provides a set of functions that may be
used to access, check and manipulate the option data.
First, the low level option handling functions. In most cases drivers would
not need to use these directly.
pointer xf86FindOption(pointer options, const char *name)
Takes a list of options and an option name, and returns a
handle for the first option entry in the list matching
the name. Returns NULL if no match is found.
char *xf86FindOptionValue(pointer options, const char *name)
Takes a list of options and an option name, and returns
the value associated with the first option entry in the
list matching the name. If the matching option has no
value, an empty string ("") is returned. Returns NULL if
no match is found.
void xf86MarkOptionUsed(pointer option)
Takes a handle for an option, and marks that option as
used.
void xf86MarkOptionUsedByName(pointer options, const char *name)
Takes a list of options and an option name and marks the
first option entry in the list matching the name as used.
Next, the higher level functions that most drivers would use.
void xf86CollectOptions(ScrnInfoPtr pScrn, pointer extraOpts)
Collect the options from each of the config file sections
used by the screen (pScrn) and return the merged list as
pScrn->options. This function requires that pScrn->conf-
Screen, pScrn->display, pScrn->monitor, pScrn->numEnti-
ties, and pScrn->entityList are initialised. extraOpts
may optionally be set to an additional list of options to
be combined with the others. The order of precedence for
options is extraOpts, display, confScreen, monitor,
device.
void xf86ProcessOptions(int scrnIndex, pointer options,
OptionInfoPtr optinfo)
Processes a list of options according to the information
in the array of OptionInfoRecs (optinfo). The resulting
information is stored in the value fields of the appro-
priate optinfo entries. The found fields are set to TRUE
when an option with a value of the correct type if found,
and FALSE otherwise. The type field is used to determine
the expected value type for each option. Each option in
the list of options for which there is a name match (but
not necessarily a value type match) is marked as used.
Warning messages are printed when option values don't
match the types specified in the optinfo data.
NOTE: If this function is called before a driver's screen
number is known (e.g., from the ChipProbe() function) a
scrnIndex value of -1 should be used.
NOTE 2: Given that this function stores into the Option-
InfoRecs pointed to by optinfo, the caller should ensure
the OptionInfoRecs are (re-)initialised before the call,
especially if the caller expects to use the predefined
option values as defaults.
The OptionInfoRec is defined as follows:
typedef struct {
double freq;
int units;
} OptFrequency;
typedef union {
unsigned long num;
char * str;
double realnum;
Bool bool;
OptFrequency freq;
} ValueUnion;
typedef enum {
OPTV_NONE = 0,
OPTV_INTEGER,
OPTV_STRING, /* a non-empty string */
OPTV_ANYSTR, /* Any string, including an empty one */
OPTV_REAL,
OPTV_BOOLEAN,
OPTV_FREQ
} OptionValueType;
typedef enum {
OPTUNITS_HZ = 1,
OPTUNITS_KHZ,
OPTUNITS_MHZ
} OptFreqUnits;
typedef struct {
int token;
const char* name;
OptionValueType type;
ValueUnion value;
Bool found;
} OptionInfoRec, *OptionInfoPtr;
OPTV_FREQ can be used for options values that are fre-
quencies. These values are a floating point number with
an optional unit name appended. The unit name can be one
of "Hz", "kHz", "k", "MHz", "M". The multiplier associ-
ated with the unit is stored in freq.units, and the
scaled frequency is stored in freq.freq. When no unit is
specified, freq.units is set to 0, and freq.freq is
unscaled.
Typical usage is to setup an array of OptionInfoRecs with
all fields initialised. The value and found fields get
set by xf86ProcessOptions(). For cases where the value
parsing is more complex, the driver should specify
OPTV_STRING, and parse the string itself. An example of
using this option handling is included in the Sample
Driver (section 20., page 1) section.
void xf86ShowUnusedOptions(int scrnIndex, pointer options)
Prints out warning messages for each option in the list
of options that isn't marked as used. This is intended
to show options that the driver hasn't recognised. It
would normally be called near the end of the Chip-
ScreenInit() function, but only when serverGenera-
tion == 1.
OptionInfoPtr xf86TokenToOptinfo(const OptionInfoRec *table,
int token)
Returns a pointer to the OptionInfoRec in table with a
token field matching token. Returns NULL if no match is
found.
Bool xf86IsOptionSet(const OptionInfoRec *table, int token)
Returns the found field of the OptionInfoRec in table
with a token field matching token. This can be used for
options of all types. Note that for options of type
OPTV_BOOLEAN, it isn't sufficient to check this to deter-
mine the value of the option. Returns FALSE if no match
is found.
char *xf86GetOptValString(const OptionInfoRec *table, int token)
Returns the value.str field of the OptionInfoRec in table
with a token field matching token. Returns NULL if no
match is found.
Bool xf86GetOptValInteger(const OptionInfoRec *table, int token,
int *value)
Returns via *value the value.num field of the OptionIn-
foRec in table with a token field matching token. *value
is only changed when a match is found so it can be safely
initialised with a default prior to calling this func-
tion. The function return value is as for xf86IsOption-
Set().
Bool xf86GetOptValULong(const OptionInfoRec *table, int token,
unsigned long *value)
Like xf86GetOptValInteger(), except the value is treated
as an unsigned long.
Bool xf86GetOptValReal(const OptionInfoRec *table, int token,
double *value)
Like xf86GetOptValInteger(), except that value.realnum is
used.
Bool xf86GetOptValFreq(const OptionInfoRec *table, int token,
OptFreqUnits expectedUnits, double *value)
Like xf86GetOptValInteger(), except that the value.freq
data is returned. The frequency value is scaled to the
units indicated by expectedUnits. The scaling is exact
when the units were specified explicitly in the option's
value. Otherwise, the expectedUnits field is used as a
hint when doing the scaling. In this case, values larger
than 1000 are assumed to have be specified in the next
smallest units. For example, if the Option value is
"10000" and expectedUnits is OPTUNITS_MHZ, the value
returned is 10.
Bool xf86GetOptValBool(const OptionInfoRec *table, int token, Bool
*value)
This function is used to check boolean options
(OPTV_BOOLEAN). If the function return value is FALSE,
it means the option wasn't set. Otherwise *value is set
to the boolean value indicated by the option's value. No
option value is interpreted as TRUE. Option values mean-
ing TRUE are "1", "yes", "on", "true", and option values
meaning FALSE are "0", "no", "off", "false". Option
names both with the "no" prefix in their names, and with
that prefix removed are also checked and handled in the
obvious way. *value is not changed when the option isn't
present. It should normally be set to a default value
before calling this function.
Bool xf86ReturnOptValBool(const OptionInfoRec *table, int token,
Bool def)
This function is used to check boolean options
(OPTV_BOOLEAN). If the option is set, its value is
returned. If the options is not set, the default value
specified by def is returned. The option interpretation
is the same as for xf86GetOptValBool().
int xf86NameCmp(const char *s1, const char *s2)
This function should be used when comparing strings from
the config file with expected values. It works like str-
cmp(), but is not case sensitive and space, tab, and `_'
characters are ignored in the comparison. The use of
this function isn't restricted to parsing option values.
It may be used anywhere where this functionality
required.
11. Modules, Drivers, Include Files and Interface Issues
NOTE: this section is incomplete.
11.1 Include files
The following include files are typically required by video drivers:
All drivers should include these:
"xf86.h"
"xf86_OSproc.h"
"xf86_ansic.h"
"xf86Resources.h"
Wherever inb/outb (and related things) are used the following
should be included:
"compiler.h"
Note: in drivers, this must be included after "xf86_ansic.h".
Drivers that need to access PCI vendor/device definitions need
this:
"xf86PciInfo.h"
Drivers that need to access the PCI config space need this:
"xf86Pci.h"
Drivers that initialise a SW cursor need this:
"mipointer.h"
All drivers implementing backing store need this:
"mibstore.h"
All drivers using the mi colourmap code need this:
"micmap.h"
If a driver uses the vgahw module, it needs this:
"vgaHW.h"
Drivers supporting VGA or Hercules monochrome screens need:
"xf1bpp.h"
Drivers supporting VGA or EGC 16-colour screens need:
"xf4bpp.h"
Drivers using cfb need:
#define PSZ 8
#include "cfb.h"
#undef PSZ
Drivers supporting bpp 16, 24 or 32 with cfb need one or more of:
"cfb16.h"
"cfb24.h"
"cfb32.h"
If a driver uses XAA, it needs these:
"xaa.h"
"xaalocal.h"
If a driver uses the fb manager, it needs this:
"xf86fbman.h"
Non-driver modules should include "xf86_ansic.h" to get the correct wrapping
of ANSI C/libc functions.
All modules must NOT include any system include files, or the following:
"xf86Priv.h"
"xf86Privstr.h"
"xf86_OSlib.h"
"Xos.h"
In addition, "xf86_libc.h" must not be included explicitly. It is included
implicitly by "xf86_ansic.h".
12. Offscreen Memory Manager
Management of offscreen video memory may be handled by the XFree86 frame-
buffer manager. Once the offscreen memory manager is running, drivers or
extensions may allocate, free or resize areas of offscreen video memory using
the following functions (definitions taken from xf86fbman.h):
typedef struct _FBArea {
ScreenPtr pScreen;
BoxRec box;
int granularity;
void (*MoveAreaCallback)(struct _FBArea*, struct _FBArea*)
void (*RemoveAreaCallback)(struct _FBArea*)
DevUnion devPrivate;
} FBArea, *FBAreaPtr;
typedef void (*MoveAreaCallbackProcPtr)(FBAreaPtr from, FBAreaPtr to)
typedef void (*RemoveAreaCallbackProcPtr)(FBAreaPtr)
FBAreaPtr xf86AllocateOffscreenArea (
ScreenPtr pScreen,
int width, int height,
int granularity,
MoveAreaCallbackProcPtr MoveAreaCallback,
RemoveAreaCallbackProcPtr RemoveAreaCallback,
pointer privData
)
void xf86FreeOffscreenArea (FBAreaPtr area)
Bool xf86ResizeOffscreenArea (
FBAreaPtr area
int w, int h
)
The function:
Bool xf86FBManagerRunning(ScreenPtr pScreen)
can be used by an extension to check if the driver has initialized the memory
manager. The manager is not available if this returns FALSE and the func-
tions above will all fail.
xf86AllocateOffscreenArea() can be used to request a rectangle of dimensions
width x height (in pixels) from unused offscreen memory. granularity speci-
fies that the leftmost edge of the rectangle must lie on some multiple of
granularity pixels. A granularity of zero means the same thing as a granu-
larity of one - no alignment preference. A MoveAreaCallback can be provided
to notify the requester when the offscreen area is moved. If no MoveArea-
Callback is supplied then the area is considered to be immovable. The priv-
Data field will be stored in the manager's internal structure for that allo-
cated area and will be returned to the requester in the FBArea passed via the
MoveAreaCallback. An optional RemoveAreaCallback is provided. If the driver
provides this it indicates that the area should be allocated with a lower
priority. Such an area may be removed when a higher priority request (one
that doesn't have a RemoveAreaCallback) is made. When this function is
called, the driver will have an opportunity to do whatever cleanup it needs
to do to deal with the loss of the area, but it must finish its cleanup
before the function exits since the offscreen memory manager will free the
area immediately after.
xf86AllocateOffscreenArea() returns NULL if it was unable to allocate the
requested area. When no longer needed, areas should be freed with xf86Free-
OffscreenArea().
xf86ResizeOffscreenArea() resizes an existing FBArea. xf86ResizeOff-
screenArea() returns TRUE if the resize was successful. If xf86ResizeOff-
screenArea() returns FALSE, the original FBArea is left unmodified. Resizing
an area maintains the area's original granularity, devPrivate, and MoveArea-
Callback. xf86ResizeOffscreenArea() has considerably less overhead than
freeing the old area then reallocating the new size, so it should be used
whenever possible.
The function:
Bool xf86QueryLargestOffscreenArea(
ScreenPtr pScreen,
int *width, int *height,
int granularity,
int preferences,
int priority
)
is provided to query the width and height of the largest single FBArea allo-
catable given a particular priority. preferences can be one of the following
to indicate whether width, height or area should be considered when determin-
ing which is the largest single FBArea available.
FAVOR_AREA_THEN_WIDTH
FAVOR_AREA_THEN_HEIGHT
FAVOR_WIDTH_THEN_AREA
FAVOR_HEIGHT_THEN_AREA
priority is one of the following:
PRIORITY_LOW
Return the largest block available without stealing any-
one else's space. This corresponds to the priority of
allocating a FBArea when a RemoveAreaCallback is pro-
vided.
PRIORITY_NORMAL
Return the largest block available if it is acceptable to
steal a lower priority area from someone. This corre-
sponds to the priority of allocating a FBArea without
providing a RemoveAreaCallback.
PRIORITY_EXTREME
Return the largest block available if all FBAreas that
aren't locked down were expunged from memory first. This
corresponds to any allocation made directly after a call
to xf86PurgeUnlockedOffscreenAreas().
The function:
Bool xf86PurgeUnlockedOffscreenAreas(ScreenPtr pScreen)
is provided as an extreme method to free up offscreen memory. This will
remove all removable FBArea allocations.
Initialization of the XFree86 framebuffer manager is done via
Bool xf86InitFBManager(ScreenPtr pScreen, BoxPtr FullBox)
FullBox represents the area of the framebuffer that the manager is allowed to
manage. This is typically a box with a width of pScrn->displayWidth and a
height of as many lines as can be fit within the total video memory, however,
the driver can reserve areas at the extremities by passing a smaller area to
the manager.
xf86InitFBManager() must be called before XAA is initialized since XAA uses
the manager for it's pixmap cache.
An alternative function is provided to allow the driver to initialize the
framebuffer manager with a Region rather than a box.
Bool xf86InitFBManagerRegion(ScreenPtr pScreen,
RegionPtr FullRegion)
xf86InitFBManagerRegion(), unlike xf86InitFBManager(), does not remove the
area used for the visible screen so that area should not be included in the
region passed to the function. xf86InitFBManagerRegion() is useful when non-
contiguous areas are available to be managed, and is required when multiple
framebuffers are stored in video memory (as in the case where an overlay of a
different depth is stored as a second framebuffer in offscreen memory).
13. Colormap Handling
A generic colormap handling layer is provided within the XFree86 common
layer. This layer takes care of most of the details, and only requires a
function from the driver that loads the hardware palette when required. To
use the colormap layer, a driver calls the xf86HandleColormaps() function.
Bool xf86HandleColormaps(ScreenPtr pScreen, int maxColors,
int sigRGBbits, LoadPaletteFuncPtr loadPalette,
SetOverscanFuncPtr setOverscan, unsigned int flags)
This function must be called after the default colormap
has been initialised. The pScrn->gamma field must also
be initialised, preferably by calling xf86SetGamma().
maxColors is the number of entries in the palette.
sigRGBbits is the size in bits of each color component in
the DAC's palette. loadPalette is a driver-provided
function for loading a colormap into the hardware, and is
described below. setOverscan is an optional function
that may be provided when the overscan color is an index
from the standard LUT and when it needs to be adjusted to
keep it as close to black as possible. The setOverscan
function programs the overscan index. It shouldn't nor-
mally be used for depths other than 8. setOverscan
should be set to NULL when it isn't needed. flags may be
set to the following (which may be ORed together):
CMAP_PALETTED_TRUECOLOR
the TrueColor visual is paletted and is just a
special case of DirectColor. This flag is only
valid for bpp > 8.
CMAP_RELOAD_ON_MODE_SWITCH
reload the colormap automatically after mode
switches. This is useful for when the driver
is resetting the hardware during mode switches
and corrupting or erasing the hardware palette.
CMAP_LOAD_EVEN_IF_OFFSCREEN
reload the colormap even if the screen is
switched out of the server's VC. The palette
is not reloaded when the screen is switched
back in, nor after mode switches. This is use-
ful when the driver needs to keep track of
palette changes.
The colormap layer normally reloads the palette after VT
enters so it is not necessary for the driver to save and
restore the palette when switching VTs. The driver must,
however, still save the initial palette during server
start up and restore it during server exit.
void LoadPalette(ScrnInfoPtr pScrn, int numColors, int *indices,
LOCO *colors, VisualPtr pVisual)
LoadPalette() is a driver-provided function for loading a
colormap into hardware. colors is the array of RGB val-
ues that represent the full colormap. indices is a list
of index values into the colors array. These indices
indicate the entries that need to be updated. numColors
is the number of the indices to be updated.
void SetOverscan(ScrnInfoPtr pScrn, int overscan)
SetOverscan() is a driver-provided function for program-
ming the overscan index. As described above, it is nor-
mally only appropriate for LUT modes where all colormap
entries are available for the display, but where one of
them is also used for the overscan (typically 8bpp for
VGA compatible LUTs). It isn't required in cases where
the overscan area is never visible.
14. DPMS Extension
Support code for the DPMS extension is included in the XFree86 common layer.
This code provides an interface between the main extension code, and a means
for drivers to initialise DPMS when they support it. One function is avail-
able to drivers to do this initialisation, and it is always available, even
when the DPMS extension is not supported by the core server (in which case it
returns a failure result).
Bool xf86DPMSInit(ScreenPtr pScreen, DPMSSetProcPtr set, int flags)
This function registers a driver's DPMS level programming
function set. It also checks pScrn->options for the
"dpms" option, and when present marks DPMS as being
enabled for that screen. The set function is called
whenever the DPMS level changes, and is used to program
the requested level. flags is currently not used, and
should be 0. If the initialisation fails for any reason,
including when there is no DPMS support in the core
server, the function returns FALSE.
Drivers that implement DPMS support must provide the following function, that
gets called when the DPMS level is changed:
void ChipDPMSSet(ScrnInfoPtr pScrn, int level, int flags)
Program the DPMS level specified by level. Valid values
of level are DPMSModeOn, DPMSModeStandby, DPMSModeSus-
pend, DPMSModeOff. These values are defined in "exten-
sions/dpms.h".
15. DGA Extension
Drivers can support the XFree86 Direct Graphics Architecture (DGA) by filling
out a structure of function pointers and a list of modes and passing them to
DGAInit.
Bool DGAInit(ScreenPtr pScreen, DGAFunctionPtr funcs,
DGAModePtr modes, int num)
/** The DGAModeRec **/
typedef struct {
int num;
DisplayModePtr mode;
int flags;
int imageWidth;
int imageHeight;
int pixmapWidth;
int pixmapHeight;
int bytesPerScanline;
int byteOrder;
int depth;
int bitsPerPixel;
unsigned long red_mask;
unsigned long green_mask;
unsigned long blue_mask;
int viewportWidth;
int viewportHeight;
int xViewportStep;
int yViewportStep;
int maxViewportX;
int maxViewportY;
int viewportFlags;
int offset;
unsigned char *address;
int reserved1;
int reserved2;
} DGAModeRec, *DGAModePtr;
num
Can be ignored. The DGA DDX will assign these
numbers.
mode
A pointer to the DisplayModeRec for this mode.
flags
The following flags are defined and may be OR'd
together:
DGA_CONCURRENT_ACCESS
Indicates that the driver supports
concurrent graphics accelerator and
linear framebuffer access.
DGA_FILL_RECT
DGA_BLIT_RECT
DGA_BLIT_RECT_TRANS
Indicates that the driver supports
the FillRect, BlitRect or BlitTran-
sRect functions in this mode.
DGA_PIXMAP_AVAILABLE
Indicates that Xlib may be used on
the framebuffer. This flag will usu-
ally be set unless the driver wishes
to prohibit this for some reason.
DGA_INTERLACED
DGA_DOUBLESCAN
Indicates that these are interlaced
or double scan modes.
imageWidth
imageHeight
These are the dimensions of the linear frame-
buffer accessible by the client.
pixmapWidth
pixmapHeight
These are the dimensions of the area of the
framebuffer accessible by the graphics acceler-
ator.
bytesPerScanline
Pitch of the framebuffer in bytes.
byteOrder
Usually the same as pScrn->imageByteOrder.
depth
The depth of the framebuffer in this mode.
bitsPerPixel
The number of bits per pixel in this mode.
red_mask
green_mask
blue_mask
The RGB masks for this mode, if applicable.
viewportWidth
viewportHeight
Dimensions of the visible part of the frame-
buffer. Usually mode->HDisplay and mode->VDis-
play.
xViewportStep
yViewportStep
The granularity of x and y viewport positions
that the driver supports in this mode.
maxViewportX
maxViewportY
The maximum viewport position supported by the
driver in this mode.
viewportFlags
The following may be OR'd together:
DGA_FLIP_IMMEDIATE
The driver supports immediate view-
port changes.
DGA_FLIP_RETRACE
The driver supports viewport changes
at retrace.
offset
The offset into the linear framebuffer that
corresponds to pixel (0,0) for this mode.
address
The virtual address of the framebuffer as
mapped by the driver. This is needed when
DGA_PIXMAP_AVAILABLE is set.
/** The DGAFunctionRec **/
typedef struct {
Bool (*OpenFramebuffer)(
ScrnInfoPtr pScrn,
char **name,
unsigned char **mem,
int *size,
int *offset,
int *extra
);
void (*CloseFramebuffer)(ScrnInfoPtr pScrn);
Bool (*SetMode)(ScrnInfoPtr pScrn, DGAModePtr pMode);
void (*SetViewport)(ScrnInfoPtr pScrn, int x, int y, int flags);
int (*GetViewport)(ScrnInfoPtr pScrn);
void (*Sync)(ScrnInfoPtr);
void (*FillRect)(
ScrnInfoPtr pScrn,
int x, int y, int w, int h,
unsigned long color
);
void (*BlitRect)(
ScrnInfoPtr pScrn,
int srcx, int srcy,
int w, int h,
int dstx, int dsty
);
void (*BlitTransRect)(
ScrnInfoPtr pScrn,
int srcx, int srcy,
int w, int h,
int dstx, int dsty,
unsigned long color
);
} DGAFunctionRec, *DGAFunctionPtr;
Bool OpenFramebuffer (pScrn, name, mem, size, offset, extra)
OpenFramebuffer() should pass the client everything it
needs to know to be able to open the framebuffer. These
parameters are OS specific and their meanings are to be
interpreted by an OS specific client library.
name
The name of the device to open or NULL if there
is no special device to open. A NULL name
tells the client that it should open whatever
device one would usually open to access physi-
cal memory.
mem
The physical address of the start of the frame-
buffer.
size
The size of the framebuffer in bytes.
offset
Any offset into the device, if applicable.
flags
Any additional information that the client may
need. Currently, only the DGA_NEED_ROOT flag
is defined.
void CloseFramebuffer (pScrn)
CloseFramebuffer() merely informs the driver (if it even
cares) that client no longer needs to access the frame-
buffer directly. This function is optional.
Bool SetMode (pScrn, pMode)
SetMode() tells the driver to initialize the mode passed
to it. If pMode is NULL, then the driver should restore
the original pre-DGA mode.
void SetViewport (pScrn, x, y, flags)
SetViewport() tells the driver to make the upper left-
hand corner of the visible screen correspond to coordi-
nate (x,y) on the framebuffer. Flags currently defined
are:
DGA_FLIP_IMMEDIATE
The viewport change should occur immediately.
DGA_FLIP_RETRACE
The viewport change should occur at the verti-
cal retrace, but this function should return
sooner if possible.
The (x,y) locations will be passed as the client speci-
fied them, however, the driver is expected to round these
locations down to the next supported location as speci-
fied by the xViewportStep and yViewportStep for the cur-
rent mode.
int GetViewport (pScrn)
GetViewport() gets the current page flip status. Set
bits in the returned int correspond to viewport change
requests still pending. For instance, set bit zero if
the last SetViewport request is still pending, bit one if
the one before that is still pending, etc.
void Sync (pScrn)
This function should ensure that any graphics accelerator
operations have finished. This function should not
return until the graphics accelerator is idle.
void FillRect (pScrn, x, y, w, h, color)
This optional function should fill a rectangle w × h
located at (x,y) in the given color.
void BlitRect (pScrn, srcx, srcy, w, h, dstx, dsty)
This optional function should copy an area w × h located
at (srcx,srcy) to location (dstx,dsty). This function
will need to handle copy directions as appropriate.
void BlitTransRect (pScrn, srcx, srcy, w, h, dstx, dsty, color)
This optional function is the same as BlitRect except
that pixels in the source corresponding to the color key
color should be skipped.
16. The XFree86 X Video Extension (Xv) Device Dependent Layer
XFree86 offers the X Video Extension which allows clients to treat video as
any another primitive and ``Put'' video into drawables. By default, the
extension reports no video adaptors as being available since the DDX layer
has not been initialized. The driver can initialize the DDX layer by filling
out one or more XF86VideoAdaptorRecs as described later in this document and
passing a list of XF86VideoAdaptorPtr pointers to the following function:
Bool xf86XVScreenInit(
ScreenPtr pScreen,
XF86VideoAdaptorPtr *adaptPtrs,
int num)
After doing this, the extension will report video adaptors as being avail-
able, providing the data in their respective XF86VideoAdaptorRecs was valid.
xf86XVScreenInit() copies data from the structure passed to it so the driver
may free it after the initialization. At the moment, the DDX only supports
rendering into Window drawables. Pixmap rendering will be supported after a
sufficient survey of suitable hardware is completed.
The XF86VideoAdaptorRec:
typedef struct {
unsigned int type;
int flags;
char *name;
int nEncodings;
XF86VideoEncodingPtr pEncodings;
int nFormats;
XF86VideoFormatPtr pFormats;
int nPorts;
DevUnion *pPortPrivates;
int nAttributes;
XF86AttributePtr pAttributes;
int nImages;
XF86ImagePtr pImages;
PutVideoFuncPtr PutVideo;
PutStillFuncPtr PutStill;
GetVideoFuncPtr GetVideo;
GetStillFuncPtr GetStill;
StopVideoFuncPtr StopVideo;
SetPortAttributeFuncPtr SetPortAttribute;
GetPortAttributeFuncPtr GetPortAttribute;
QueryBestSizeFuncPtr QueryBestSize;
PutImageFuncPtr PutImage;
QueryImageAttributesFuncPtr QueryImageAttributes;
} XF86VideoAdaptorRec, *XF86VideoAdaptorPtr;
Each adaptor will have its own XF86VideoAdaptorRec. The fields are
as follows:
type
This can be any of the following flags OR'd together.
XvInputMask XvOutputMask
These refer to the target drawable and are sim-
ilar to a Window's class. XvInputMask indicates
that the adaptor can put video into a drawable.
XvOutputMask indicates that the adaptor can get
video from a drawable.
XvVideoMask XvStillMask XvImageMask
These indicate that the adaptor supports video,
still or image primitives respectively.
XvWindowMask XvPixmapMask
These indicate the types of drawables the adap-
tor is capable of rendering into. At the
moment, Pixmap rendering is not supported and
the XvPixmapMask flag is ignored.
flags
Currently, the following flags are defined:
VIDEO_NO_CLIPPING
This indicates that the video adaptor does not
support clipping. The driver will never
receive ``Put'' requests where less than the
entire area determined by drw_x, drw_y, drw_w
and drw_h is visible. This flag does not apply
to ``Get'' requests. Hardware that is inca-
pable of clipping ``Gets'' may punt or get the
extents of the clipping region passed to it.
VIDEO_INVERT_CLIPLIST
This indicates that the video driver requires
the clip list to contain the regions which are
obscured rather than the regions which are are
visible.
VIDEO_OVERLAID_STILLS
Implementing PutStill for hardware that does
video as an overlay can be awkward since it's
unclear how long to leave the video up for.
When this flag is set, StopVideo will be called
whenever the destination gets clipped or moved
so that the still can be left up until then.
VIDEO_OVERLAID_IMAGES
Same as VIDEO_OVERLAID_STILLS but for images.
VIDEO_CLIP_TO_VIEWPORT
Indicates that the clip region passed to the
driver functions should be clipped to the visi-
ble portion of the screen in the case where the
viewport is smaller than the virtual desktop.
name
The name of the adaptor.
nEncodings
pEncodings
The number of encodings the adaptor is capable of and
pointer to the XF86VideoEncodingRec array. The
XF86VideoEncodingRec is described later on. For drivers
that only support XvImages there should be an encoding
named "XV_IMAGE" and the width and height should specify
the maximum size source image supported.
nFormats
pFormats
The number of formats the adaptor is capable of and
pointer to the XF86VideoFormatRec array. The XF86Video-
FormatRec is described later on.
nPorts
pPortPrivates
The number of ports is the number of separate data
streams which the adaptor can handle simultaneously. If
you have more than one port, the adaptor is expected to
be able to render into more than one window at a time.
pPortPrivates is an array of pointers or ints - one for
each port. A port's private data will be passed to the
driver any time the port is requested to do something
like put the video or stop the video. In the case where
there may be many ports, this enables the driver to know
which port the request is intended for. Most commonly,
this will contain a pointer to the data structure con-
taining information about the port. In Xv, all ports on
a particular adaptor are expected to be identical in
their functionality.
nAttributes
pAttributes
The number of attributes recognized by the adaptor and a
pointer to the array of XF86AttributeRecs. The
XF86AttributeRec is described later on.
nImages
pImages
The number of XF86ImageRecs supported by the adaptor and
a pointer to the array of XF86ImageRecs. The XF86ImageRec
is described later on.
PutVideo PutStill GetVideo GetStill StopVideo SetPortAttribute Get-
PortAttribute QueryBestSize PutImage QueryImageAttributes
These functions define the DDX->driver interface. In
each case, the pointer data is passed to the driver.
This is the port private for that port as described
above. All fields are required except under the follow-
ing conditions:
1. PutVideo, PutStill and the image routines PutImage
and QueryImageAttributes are not required when the
adaptor type does not contain XvInputMask.
2. GetVideo and GetStill are not required when the
adaptor type does not contain XvOutputMask.
3. GetVideo and PutVideo are not required when the
adaptor type does not contain XvVideoMask.
4. GetStill and PutStill are not required when the
adaptor type does not contain XvStillMask.
5. PutImage and QueryImageAttributes are not required
when the adaptor type does not contain XvImageMask.
With the exception of QueryImageAttributes, these func-
tions should return Success if the operation was com-
pleted successfully. They can return XvBadAlloc other-
wise. QueryImageAttributes returns the size of the XvIm-
age queried.
If the VIDEO_NO_CLIPPING flag is set, the clipBoxes may
be ignored by the driver. ClipBoxes is an X-Y banded
region identical to those used throughout the server.
The clipBoxes represent the visible portions of the area
determined by drw_x, drw_y, drw_w and drw_h in the
Get/Put function. The boxes are in screen coordinates,
are guaranteed not to overlap and an empty region will
never be passed. If the driver has specified
VIDEO_INVERT_CLIPLIST, clipBoxes will indicate the areas
of the primitive which are obscured rather than the areas
visible.
typedef int (* PutVideoFuncPtr)( ScrnInfoPtr pScrn,
short vid_x, short vid_y, short drw_x, short drw_y,
short vid_w, short vid_h, short drw_w, short drw_h,
RegionPtr clipBoxes, pointer data )
This indicates that the driver should take a subsection
vid_w by vid_h at location (vid_x,vid_y) from the video
stream and direct it into the rectangle drw_w by drw_h at
location (drw_x,drw_y) on the screen, scaling as neces-
sary. Due to the large variations in capabilities of the
various hardware expected to be used with this extension,
it is not expected that all hardware will be able to do
this exactly as described. In that case the driver
should just do ``the best it can,'' scaling as closely to
the target rectangle as it can without rendering outside
of it. In the worst case, the driver can opt to just not
turn on the video.
typedef int (* PutStillFuncPtr)( ScrnInfoPtr pScrn,
short vid_x, short vid_y, short drw_x, short drw_y,
short vid_w, short vid_h, short drw_w, short drw_h,
RegionPtr clipBoxes, pointer data )
This is same as PutVideo except that the driver should
place only one frame from the stream on the screen.
typedef int (* GetVideoFuncPtr)( ScrnInfoPtr pScrn,
short vid_x, short vid_y, short drw_x, short drw_y,
short vid_w, short vid_h, short drw_w, short drw_h,
RegionPtr clipBoxes, pointer data )
This is same as PutVideo except that the driver gets
video from the screen and outputs it. The driver should
do the best it can to get the requested dimensions cor-
rect without reading from an area larger than requested.
typedef int (* GetStillFuncPtr)( ScrnInfoPtr pScrn,
short vid_x, short vid_y, short drw_x, short drw_y,
short vid_w, short vid_h, short drw_w, short drw_h,
RegionPtr clipBoxes, pointer data )
This is the same as GetVideo except that the driver
should place only one frame from the screen into the out-
put stream.
typedef void (* StopVideoFuncPtr)(ScrnInfoPtr pScrn,
pointer data, Bool cleanup)
This indicates the driver should stop displaying the
video. This is used to stop both input and output video.
The cleanup field indicates that the video is being
stopped because the client requested it to stop or
because the server is exiting the current VT. In that
case the driver should deallocate any offscreen memory
areas (if there are any) being used to put the video to
the screen. If cleanup is not set, the video is being
stopped temporarily due to clipping or moving of the win-
dow, etc... and video will likely be restarted soon so
the driver should not deallocate any offscreen areas
associated with that port.
typedef int (* SetPortAttributeFuncPtr)(ScrnInfoPtr pScrn,
Atom attribute,INT32 value, pointer data)
typedef int (* GetPortAttributeFuncPtr)(ScrnInfoPtr pScrn,
Atom attribute,INT32 *value, pointer data)
A port may have particular attributes such as hue, satu-
ration, brightness or contrast. Xv clients set and get
these attribute values by sending attribute strings
(Atoms) to the server. Such requests end up at these
driver functions. It is recommended that the driver pro-
vide at least the following attributes mentioned in the
Xv client library docs:
XV_ENCODING
XV_HUE
XV_SATURATION
XV_BRIGHTNESS
XV_CONTRAST
but the driver may recognize as many atoms as it wishes.
If a requested attribute is unknown by the driver it
should return BadMatch. XV_ENCODING is the attribute
intended to let the client specify which video encoding
the particular port should be using (see the description
of XF86VideoEncodingRec below). If the requested encod-
ing is unsupported, the driver should return XvBadEncod-
ing. If the value lies outside the advertised range Bad-
Value may be returned. Success should be returned other-
wise.
typedef void (* QueryBestSizeFuncPtr)(ScrnInfoPtr pScrn,
Bool motion, short vid_w, short vid_h,
short drw_w, short drw_h,
unsigned int *p_w, unsigned int *p_h, pointer data)
QueryBestSize provides the client with a way to query
what the destination dimensions would end up being if
they were to request that an area vid_w by vid_h from the
video stream be scaled to rectangle of drw_w by drw_h on
the screen. Since it is not expected that all hardware
will be able to get the target dimensions exactly, it is
important that the driver provide this function.
typedef int (* PutImageFuncPtr)( ScrnInfoPtr pScrn,
short src_x, short src_y, short drw_x, short drw_y,
short src_w, short src_h, short drw_w, short drw_h,
int image, char *buf, short width, short height,
Bool sync, RegionPtr clipBoxes, pointer data )
This is similar to PutStill except that the source of the
video is not a port but the data stored in a system mem-
ory buffer at buf. The data is in the format indicated
by the image descriptor and represents a source of size
width by height. If sync is TRUE the driver should not
return from this function until it is through reading the
data from buf. Returning when sync is TRUE indicates
that it is safe for the data at buf to be replaced,
freed, or modified.
typedef int (* QueryImageAttributesFuncPtr)( ScrnInfoPtr pScrn,
int image, short *width, short *height,
int *pitches, int *offsets)
This function is called to let the driver specify how
data for a particular image of size width by height
should be stored. Sometimes only the size and corrected
width and height are needed. In that case pitches and
offsets are NULL. The size of the memory required for
the image is returned by this function. The width and
height of the requested image can be altered by the
driver to reflect format limitations (such as component
sampling periods that are larger than one). If pitches
and offsets are not NULL, these will be arrays with as
many elements in them as there are planes in the image
format. The driver should specify the pitch (in bytes)
of each scanline in the particular plane as well as the
offset to that plane (in bytes) from the beginning of the
image.
The XF86VideoEncodingRec:
typedef struct {
int id;
char *name;
unsigned short width, height;
XvRationalRec rate;
} XF86VideoEncodingRec, *XF86VideoEncodingPtr;
The XF86VideoEncodingRec specifies what encodings the adaptor can
support. Most of this data is just informational and for the
client's benefit, and is what will be reported by XvQueryEncodings.
The id field is expected to be a unique identifier to allow the
client to request a certain encoding via the XV_ENCODING attribute
string.
The XF86VideoFormatRec:
typedef struct {
char depth;
short class;
} XF86VideoFormatRec, *XF86VideoFormatPtr;
This specifies what visuals the video is viewable in. depth is the
depth of the visual (not bpp). class is the visual class such as
TrueColor, DirectColor or PseudoColor. Initialization of an adap-
tor will fail if none of the visuals on that screen are supported.
The XF86AttributeRec:
typedef struct {
int flags;
int min_value;
int max_value;
char *name;
} XF86AttributeListRec, *XF86AttributeListPtr;
Each adaptor may have an array of these advertising the attributes
for its ports. Currently defined flags are XvGettable and XvSet-
table which may be OR'd together indicating that attribute is
``gettable'' or ``settable'' by the client. The min and max field
specify the valid range for the value. Name is a text string
describing the attribute by name.
The XF86ImageRec:
typedef struct {
int id;
int type;
int byte_order;
char guid[16];
int bits_per_pixel;
int format;
int num_planes;
/* for RGB formats */
int depth;
unsigned int red_mask;
unsigned int green_mask;
unsigned int blue_mask;
/* for YUV formats */
unsigned int y_sample_bits;
unsigned int u_sample_bits;
unsigned int v_sample_bits;
unsigned int horz_y_period;
unsigned int horz_u_period;
unsigned int horz_v_period;
unsigned int vert_y_period;
unsigned int vert_u_period;
unsigned int vert_v_period;
char component_order[32];
int scanline_order;
} XF86ImageRec, *XF86ImagePtr;
XF86ImageRec describes how video source data is laid out in memory.
The fields are as follows:
id
This is a unique descriptor for the format. It is often
good to set this value to the FOURCC for the format when
applicable.
type
This is XvRGB or XvYUV.
byte_order
This is LSBFirst or MSBFirst.
guid
This is the Globally Unique IDentifier for the format.
When not applicable, all characters should be NULL.
bits_per_pixel
The number of bits taken up (but not necessarily used) by
each pixel. Note that for some planar formats which have
fractional bits per pixel (such as IF09) this number may
be rounded _down_.
format
This is XvPlanar or XvPacked.
num_planes
The number of planes in planar formats. This should be
set to one for packed formats.
depth
The significant bits per pixel in RGB formats (analgous
to the depth of a pixmap format).
red_mask green_mask blue_mask
The red, green and blue bitmasks for packed RGB formats.
y_sample_bits u_sample_bits v_sample_bits
The y, u and v sample sizes (in bits).
horz_y_period horz_u_period horz_v_period
The y, u and v sampling periods in the horizontal direc-
tion.
vert_y_period vert_u_period vert_v_period
The y, u and v sampling periods in the vertical direc-
tion.
component_order
Uppercase ascii characters representing the order that
samples are stored within packed formats. For planar
formats this represents the ordering of the planes.
Unused characters in the 32 byte string should be set to
NULL.
scanline_order
This is XvTopToBottom or XvBottomToTop.
Since some formats (particular some planar YUV formats) may not be
completely defined by the parameters above, the guid, when avail-
able, should provide the most accurate description of the format.
17. The Loader
This section describes the interfaces to the module loader. The loader
interfaces can be divided into two groups: those that are only available to
the XFree86 common layer, and those that are also available to modules.
17.1 Loader Overview
The loader is capable of loading modules in a range of object formats, and
knowledge of these formats is built in to the loader. Knowledge of new
object formats can be added to the loader in a straightforward manner. This
makes it possible to provide OS-independent modules (for a given CPU archi-
tecture type). In addition to this, the loader can load modules via the OS-
provided dlopen(3) service where available. Such modules are not platform
independent, and the semantics of dlopen() on most systems results in signif-
icant limitations in the use of modules of this type. Support for dlopen()
modules in the loader is primarily for experimental and development purposes.
Symbols exported by the loader (on behalf of the core X server) to modules
are determined at compile time. Only those symbols explicitly exported are
available to modules. All external symbols of loaded modules are exported to
other modules, and to the core X server. The loader can be requested to
check for unresolved symbols at any time, and the action to be taken for
unresolved symbols can be controlled by the caller of the loader. Typically
the caller identifies which symbols can safely remain unresolved and which
cannot.
NOTE: Now that ISO-C allows pointers to functions and pointers to data to
have different internal representations, some of the following interfaces
will need to be revisited.
17.2 Semi-private Loader Interface
The following is the semi-private loader interface that is available to the
XFree86 common layer.
void LoaderInit(void)
The LoaderInit() function initialises the loader, and it
must be called once before calling any other loader func-
tions. This function initialises the tables of exported
symbols, and anything else that might need to be ini-
tialised.
void LoaderSetPath(const char *path)
The LoaderSetPath() function initialises a default module
search path. This must be called if calls to other func-
tions are to be made without explicitly specifying a mod-
ule search path. The search path path must be a string
of one or more comma separated absolute paths. Modules
are expected to be located below these paths, possibly in
subdirectories of these paths.
pointer LoadModule(const char *module, const char *path,
const char **subdirlist, const char **patternlist,
pointer options, const XF86ModReqInfo * modreq,
int *errmaj, int *errmin)
The LoadModule() function loads the module called module.
The return value is a module handle, and may be used in
future calls to the loader that require a reference to a
loaded module. The module name module is normally the
module's canonical name, which doesn't contain any direc-
tory path information, or any object/library file pre-
fixes of suffixes. Currently a full pathname and/or
filename is also accepted. This might change. The other
parameters are:
path
An optional comma-separated list of module
search paths. When NULL, the default search
path is used.
subdirlist
An optional NULL terminated list of subdirecto-
ries to search. When NULL, the default built-
in list is used (refer to stdSubdirs in load-
mod.c). The default list is also substituted
for entries in subdirlist with the value
DEFAULT_LIST. This makes is possible to aug-
ment the default list instead of replacing it.
Subdir elements must be relative, and must not
contain "..". If any violate this requirement,
the load fails.
patternlist
An optional NULL terminated list of POSIX regu-
lar expressions used to connect module file-
names with canonical module names. Each regex
should contain exactly one subexpression that
corresponds to the canonical module name. When
NULL, the default built-in list is used (refer
to stdPatterns in loadmod.c). The default list
is also substituted for entries in patternlist
with the value DEFAULT_LIST. This makes it
possible to augment the default list instead of
replacing it.
options
An optional parameter that is passed to the
newly loaded module's SetupProc function (if it
has one). This argument is normally a NULL
terminated list of Options, and must be inter-
preted that way by modules loaded directly by
the XFree86 common layer. However, it may be
used for application-specific parameter passing
in other situations.
When loading ``external'' modules (modules that
don't have the standard entry point, for exam-
ple a special shared library) the options
parameter can be set to EXTERN_MODULE to tell
the loader not to reject the module when it
doesn't find the standard entry point.
modreq
An optional XF86ModReqInfo* containing ver-
sion/ABI/vendor information to requirements to
check the newly loaded module against. The
main purpose of this is to allow the loader to
verify that a module of the correct type/ver-
sion before running its SetupProc function.
The XF86ModReqInfo struct is defined as fol-
lows:
typedef struct {
CARD8 majorversion; /* MAJOR_UNSPEC */
CARD8 minorversion; /* MINOR_UNSPEC */
CARD16 patchlevel; /* PATCH_UNSPEC */
const char * abiclass; /* ABI_CLASS_NONE */
CARD32 abiversion; /* ABI_VERS_UNSPEC */
const char * moduleclass; /* MOD_CLASS_NONE */
} XF86ModReqInfo;
The information here is compared against the
equivalent information in the module's XF86Mod-
uleVersionInfo record (which is described
below). The values in comments above indicate
``don't care'' settings for each of the fields.
The comparisons made are as follows:
majorversion
Must match the module's majorversion
exactly.
minorversion
The module's minor version must be no
less than this value. This compari-
son is only made if majorversion is
specified and matches.
patchlevel
The module's patchlevel must be no
less than this value. This compari-
son is only made if minorversion is
specified and matches.
abiclass
String must match the module's abi-
class string.
abiversion
Must be consistent with the module's
abiversion (major equal, minor no
older).
moduleclass
String must match the module's mod-
uleclass string.
errmaj
An optional pointer to a variable holding the
major part or the error code. When provided,
*errmaj is filled in when LoadModule() fails.
errmin
Like errmaj, but for the minor part of the
error code.
void UnloadModule(pointer mod)
This function unloads the module referred to by the han-
dle mod. All child modules are also unloaded recur-
sively. This function must not be used to directly
unload modules that are child modules (i.e., those that
have been loaded with the LoadSubModule() described
below).
17.3 Module Requirements
Modules must provide information about themselves to the loader, and may
optionally provide entry points for "setup" and "teardown" functions (those
two functions are referred to here as SetupProc and TearDownProc).
The module information is contained in the XF86ModuleVersionInfo struct,
which is defined as follows:
typedef struct {
const char * modname; /* name of module, e.g. "foo" */
const char * vendor; /* vendor specific string */
CARD32 _modinfo1_; /* constant MODINFOSTRING1/2 to find */
CARD32 _modinfo2_; /* infoarea with a binary editor/sign tool */
CARD32 xf86version; /* contains XF86_VERSION_CURRENT */
CARD8 majorversion; /* module-specific major version */
CARD8 minorversion; /* module-specific minor version */
CARD16 patchlevel; /* module-specific patch level */
const char * abiclass; /* ABI class that the module uses */
CARD32 abiversion; /* ABI version */
const char * moduleclass; /* module class */
CARD32 checksum[4]; /* contains a digital signature of the */
/* version info structure */
} XF86ModuleVersionInfo;
The fields are used as follows:
modname
The module's name. This field is currently only for
informational purposes, but the loader may be modified in
future to require it to match the module's canonical
name.
vendor
The module vendor. This field is for informational pur-
poses only.
_modinfo1_
This field holds the first part of a signature that can
be used to locate this structure in the binary. It
should always be initialised to MODINFOSTRING1.
_modinfo2_
This field holds the second part of a signature that can
be used to locate this structure in the binary. It
should always be initialised to MODINFOSTRING2.
xf86version
The XFree86 version against which the module was com-
piled. This is mostly for informational/diagnostic pur-
poses. It should be initialised to XF86_VERSION_CURRENT,
which is defined in xf86Version.h.
majorversion
The module-specific major version. For modules where
this version is used for more than simply informational
purposes, the major version should only change (be incre-
mented) when ABI incompatibilities are introduced, or ABI
components are removed.
minorversion
The module-specific minor version. For modules where
this version is used for more than simply informational
purposes, the minor version should only change (be incre-
mented) when ABI additions are made in a backward compat-
ible way. It should be reset to zero when the major ver-
sion is increased.
patchlevel
The module-specific patch level. The patch level should
increase with new revisions of the module where there are
no ABI changes, and it should be reset to zero when the
minor version is increased.
abiclass
The ABI class that the module requires. The class is
specified as a string for easy extensibility. It should
indicate which (if any) of the X server's built-in ABI
classes that the module relies on, or a third-party ABI
if appropriate. Built-in ABI classes currently defined
are:
ABI_CLASS_NONE
no class
ABI_CLASS_ANSIC
only requires the ANSI C interfaces
ABI_CLASS_VIDEODRV
requires the video driver ABI
ABI_CLASS_XINPUT
requires the XInput driver ABI
ABI_CLASS_EXTENSION
requires the extension module ABI
ABI_CLASS_FONT
requires the font module ABI
abiversion
The version of abiclass that the module requires. The
version consists of major and minor components. The
major version must match and the minor version must be no
newer than that provided by the server or parent module.
Version identifiers for the built-in classes currently
defined are:
ABI_ANSIC_VERSION
ABI_VIDEODRV_VERSION
ABI_XINPUT_VERSION
ABI_EXTENSION_VERSION
ABI_FONT_VERSION
moduleclass
This is similar to the abiclass field, except that it
defines the type of module rather than the ABI it
requires. For example, although all video drivers
require the video driver ABI, not all modules that
require the video driver ABI are video drivers. This
distinction can be made with the moduleclass. Currently
pre-defined module classes are:
MOD_CLASS_NONE
MOD_CLASS_VIDEODRV
MOD_CLASS_XINPUT
MOD_CLASS_FONT
MOD_CLASS_EXTENSION
checksum
Not currently used.
The module version information, and the optional SetupProc and TearDownProc
entry points are found by the loader by locating a data object in the module
called "modnameModuleData", where "modname" is the canonical name of the mod-
ule. Modules must contain such a data object, and it must be declared with
global scope, be compile-time initialised, and is of the following type:
typedef struct {
XF86ModuleVersionInfo * vers;
ModuleSetupProc setup;
ModuleTearDownProc teardown;
} XF86ModuleData;
The vers parameter must be initialised to a pointer to a correctly ini-
tialised XF86ModuleVersionInfo struct. The other two parameter are optional,
and should be initialised to NULL when not required. The other parameters
are defined as
typedef pointer (*ModuleSetupProc)(pointer, pointer, int *, int *)
typedef void (*ModuleTearDownProc)(pointer)
pointer SetupProc(pointer module, pointer options,
int *errmaj, int *errmin)
When defined, this function is called by the loader after
successfully loading a module. module is a handle for
the newly loaded module, and maybe used by the SetupProc
if it calls other loader functions that require a refer-
ence to it. The remaining arguments are those that were
passed to the LoadModule() (or LoadSubModule()), and are
described above. When the SetupProc is successful it must
return a non-NULL value. The loader checks this, and if
it is NULL it unloads the module and reports the failure
to the caller of LoadModule(). If the SetupProc does
things that need to be undone when the module is
unloaded, it should define a TearDownProc, and return a
pointer that the TearDownProc can use to undo what has
been done.
When a module is loaded multiple times, the SetupProc is
called once for each time it is loaded.
void TearDownProc(pointer tearDownData)
When defined, this function is called when the loader
unloads a module. The tearDownData parameter is the
return value of the SetupProc() that was called when the
module was loaded. The purpose of this function is to
clean up before the module is unloaded (for example, by
freeing allocated resources).
17.4 Public Loader Interface
The following is the Loader interface that is available to any part of the
server, and may also be used from within modules.
pointer LoadSubModule(pointer parent, const char *module,
const char **subdirlist, const char **patternlist,
pointer options, const XF86ModReqInfo * modreq,
int *errmaj, int *errmin)
This function is like the LoadModule() function described
above, except that the module loaded is registered as a
child of the calling module. The parent parameter is the
calling module's handle. Modules loaded with this func-
tion are automatically unloaded when the parent module is
unloaded. The other difference is that the path parame-
ter may not be specified. The module search path used
for modules loaded with this function is the default
search path as initialised with LoaderSetPath().
void UnloadSubModule(pointer module)
This function unloads the module with handle module. If
that module itself has children, they are also unloaded.
It is like UnloadModule(), except that it is safe to use
for unloading child modules.
pointer LoaderSymbol(const char *symbol)
This function returns the address of the symbol with name
symbol. This may be used to locate a module entry point
with a known name.
char **LoaderlistDirs(const char **subdirlist,
const char **patternlist)
This function returns a NULL terminated list of canonical
modules names for modules found in the default module
search path. The subdirlist and patternlist parameters
are as described above, and can be used to control the
locations and names that are searched. If no modules are
found, the return value is NULL. The returned list
should be freed by calling LoaderFreeDirList() when it is
no longer needed.
void LoaderFreeDirList(char **list)
This function frees a module list created by Loaderlist-
Dirs().
void LoaderReqSymLists(const char **list0, ...)
This function allows the registration of required symbols
with the loader. It is normally used by a caller of
LoadSubModule(). If any symbols registered in this way
are found to be unresolved when LoaderCheckUnresolved()
is called then LoaderCheckUnresolved() will report a
failure. The function takes one or more NULL terminated
lists of symbols. The end of the argument list is indi-
cated by a NULL argument.
void LoaderReqSymbols(const char *sym0, ...)
This function is like LoaderReqSymLists() except that its
arguments are symbols rather than lists of symbols. This
function is more convenient when single functions are to
be registered, especially when the single function might
depend on runtime factors. The end of the argument list
is indicated by a NULL argument.
void LoaderRefSymLists(const char **list0, ...)
This function allows the registration of possibly unre-
solved symbols with the loader. When LoaderCheckUnre-
solved() is run it won't generate warnings for symbols
registered in this way unless they were also registered
as required symbols. The function takes one or more NULL
terminated lists of symbols. The end of the argument
list is indicated by a NULL argument.
void LoaderRefSymbols(const char *sym0, ...)
This function is like LoaderRefSymLists() except that its
arguments are symbols rather than lists of symbols. This
function is more convenient when single functions are to
be registered, especially when the single function might
depend on runtime factors. The end of the argument list
is indicated by a NULL argument.
int LoaderCheckUnresolved(int delayflag)
This function checks for unresolved symbols. It gener-
ates warnings for unresolved symbols that have not been
registered with LoaderRefSymLists(), and maps them to a
dummy function. This behaviour may change in future. If
unresolved symbols are found that have been registered
with LoaderReqSymLists() or LoaderReqSymbols() then this
function returns a non-zero value. If none of these sym-
bols are unresolved the return value is zero, indicating
success.
The delayflag parameter should normally be set to
LD_RESOLV_IFDONE.
LoaderErrorMsg(const char *name, const char *modname,
int errmaj, int errmin)
This function prints an error message that includes the
text ``Failed to load module'', the module name modname,
a message specific to the errmaj value, and the value if
errmin. If name is non-NULL, it is printed as an identi-
fying prefix to the message (followed by a `:').
17.5 Special Registration Functions
The loader contains some functions for registering some classes of modules.
These may be moved out of the loader at some point.
void LoadExtension(ExtensionModule *ext)
This registers the entry points for the extension identi-
fied by ext. The ExtensionModule struct is defined as:
typedef struct {
InitExtension initFunc;
char * name;
Bool *disablePtr;
InitExtension setupFunc;
} ExtensionModule;
void LoadFont(FontModule *font)
This registers the entry points for the font rasteriser
module identified by font. The FontModule struct is
defined as:
typedef struct {
InitFont initFunc;
char * name;
pointer module;
} FontModule;
18. Helper Functions
This section describe ``helper'' functions that video driver might find use-
ful. While video drivers are not required to use any of these to be consid-
ered ``compliant'', the use of appropriate helpers is strongly encouraged to
improve the consistency of driver behaviour.
18.1 Functions for printing messages
ErrorF(const char *format, ...)
This is the basic function for writing to the error log
(typically stderr and/or a log file). Video drivers
should usually avoid using this directly in favour of the
more specialised functions described below. This func-
tion is useful for printing messages while debugging a
driver.
FatalError(const char *format, ...)
This prints a message and causes the Xserver to abort.
It should rarely be used within a video driver, as most
error conditions should be flagged by the return values
of the driver functions. This allows the higher layers
to decide how to proceed. In rare cases, this can be
used within a driver if a fatal unexpected condition is
found.
xf86ErrorF(const char *format, ...)
This is like ErrorF(), except that the message is only
printed when the Xserver's verbosity level is set to the
default (1) or higher. It means that the messages are
not printed when the server is started with the -quiet
flag. Typically this function would only be used for
continuing messages started with one of the more spe-
cialised functions described below.
xf86ErrorFVerb(int verb, const char *format, ...)
Like xf86ErrorF(), except the minimum verbosity level for
which the message is to be printed is given explicitly.
Passing a verb value of zero means the message is always
printed. A value higher than 1 can be used for informa-
tion would normally not be needed, but which might be
useful when diagnosing problems.
xf86Msg(MessageType type, const char *format, ...)
This is like xf86ErrorF(), except that the message is
prefixed with a marker determined by the value of type.
The marker is used to indicate the type of message (warn-
ing, error, probed value, config value, etc). Note the
xf86Verbose value is ignored for messages of type
X_ERROR.
The marker values are:
X_PROBED
Value was probed.
X_CONFIG
Value was given in the config file.
X_DEFAULT
Value is a default.
X_CMDLINE
Value was given on the command line.
X_NOTICE
Notice.
X_ERROR
Error message.
X_WARNING
Warning message.
X_INFO
Informational message.
X_NONE
No prefix.
X_NOT_IMPLEMENTED
The message relates to functionality
that is not yet implemented.
xf86MsgVerb(MessageType type, int verb, const char *format, ...)
Like xf86Msg(), but with the verbosity level given
explicitly.
xf86DrvMsg(int scrnIndex, MessageType type, const char *format,
...)
This is like xf86Msg() except that the driver's name (the
name field of the ScrnInfoRec) followed by the scrnIndex
in parentheses is printed following the prefix. This
should be used by video drivers in most cases as it
clearly indicates which driver/screen the message is for.
If scrnIndex is negative, this function behaves exactly
like xf86Msg().
NOTE: This function can only be used after the ScrnIn-
foRec and its name field have been allocated. Normally,
this means that it can not be used before the END of the
ChipProbe() function. Prior to that, use xf86Msg(), pro-
viding the driver's name explicitly. No screen number
can be supplied at that point.
xf86DrvMsgVerb(int scrnIndex, MessageType type, int verb,
const char *format, ...)
Like xf86DrvMsg(), but with the verbosity level given
explicitly.
18.2 Functions for setting values based on command line and config file
Bool xf86SetDepthBpp(ScrnInfoPtr scrp, int depth, int bpp,
int fbbpp, int depth24flags)
This function sets the depth, pixmapBPP and bitsPerPixel
fields of the ScrnInfoRec. It also determines the
defaults for display-wide attributes and pixmap formats
the screen will support, and finds the Display subsection
that matches the depth/bpp. This function should nor-
mally be called very early from the ChipPreInit() func-
tion.
It requires that the confScreen field of the ScrnInfoRec
be initialised prior to calling it. This is done by the
XFree86 common layer prior to calling ChipPreInit().
The parameters passed are:
depth
driver's preferred default depth if no other is
given. If zero, use the overall server
default.
bpp
Same, but for the pixmap bpp.
fbbpp
Same, but for the framebuffer bpp.
depth24flags
Flags that indicate the level of 24/32bpp sup-
port and whether conversion between different
framebuffer and pixmap formats is supported.
The flags for this argument are defined as fol-
lows, and multiple flags may be ORed together:
NoDepth24Support
No depth 24 formats supported
Support24bppFb
24bpp framebuffer supported
Support32bppFb
32bpp framebuffer supported
SupportConvert24to32
Can convert 24bpp pixmap to 32bpp fb
SupportConvert32to24
Can convert 32bpp pixmap to 24bpp fb
ForceConvert24to32
Force 24bpp pixmap to 32bpp fb con-
version
ForceConvert32to24
Force 32bpp pixmap to 24bpp fb con-
version
It uses the command line, config file, and default values
in the correct order of precedence to determine the depth
and bpp values. It is up to the driver to check the
results to see that it supports them. If not the Chip-
PreInit() function should return FALSE.
If only one of depth/bpp is given, the other is set to a
reasonable (and consistent) default.
If a driver finds that the initial depth24flags it uses
later results in a fb format that requires more video
memory than is available it may call this function a sec-
ond time with a different depth24flags setting.
On success, the return value is TRUE. On failure it
prints an error message and returns FALSE.
The following fields of the ScrnInfoRec are initialised
by this function:
depth, bitsPerPixel, display, imageByteOrder,
bitmapScanlinePad, bitmapScanlineUnit, bitmap-
BitOrder, numFormats, formats, fbFormat.
void xf86PrintDepthBpp(scrnInfoPtr scrp)
This function can be used to print out the depth and bpp
settings. It should be called after the final call to
xf86SetDepthBpp().
Bool xf86SetWeight(ScrnInfoPtr scrp, rgb weight, rgb mask)
This function sets the weight, mask, offset and rgbBits
fields of the ScrnInfoRec. It would normally be called
fairly early in the ChipPreInit() function for
depths > 8bpp.
It requires that the depth and display fields of the
ScrnInfoRec be initialised prior to calling it.
The parameters passed are:
weight
driver's preferred default weight if no other
is given. If zero, use the overall server
default.
mask
Same, but for mask.
It uses the command line, config file, and default values
in the correct order of precedence to determine the
weight value. It derives the mask and offset values from
the weight and the defaults. It is up to the driver to
check the results to see that it supports them. If not
the ChipPreInit() function should return FALSE.
On success, this function prints a message showing the
weight values selected, and returns TRUE.
On failure it prints an error message and returns FALSE.
The following fields of the ScrnInfoRec are initialised
by this function:
weight, mask, offset.
Bool xf86SetDefaultVisual(ScrnInfoPtr scrp, int visual)
This function sets the defaultVisual field of the ScrnIn-
foRec. It would normally be called fairly early from the
ChipPreInit() function.
It requires that the depth and display fields of the
ScrnInfoRec be initialised prior to calling it.
The parameters passed are:
visual
driver's preferred default visual if no other
is given. If -1, use the overall server
default.
It uses the command line, config file, and default values
in the correct order of precedence to determine the
default visual value. It is up to the driver to check
the result to see that it supports it. If not the Chip-
PreInit() function should return FALSE.
On success, this function prints a message showing the
default visual selected, and returns TRUE.
On failure it prints an error message and returns FALSE.
Bool xf86SetGamma(ScrnInfoPtr scrp, Gamma gamma)
This function sets the gamma field of the ScrnInfoRec.
It would normally be called fairly early from the Chip-
PreInit() function in cases where the driver supports
gamma correction.
It requires that the monitor field of the ScrnInfoRec be
initialised prior to calling it.
The parameters passed are:
gamma
driver's preferred default gamma if no other is
given. If zero (< 0.01), use the overall
server default.
It uses the command line, config file, and default values
in the correct order of precedence to determine the gamma
value. It is up to the driver to check the results to
see that it supports them. If not the ChipPreInit()
function should return FALSE.
On success, this function prints a message showing the
gamma value selected, and returns TRUE.
On failure it prints an error message and returns FALSE.
void xf86SetDpi(ScrnInfoPtr pScrn, int x, int y)
This function sets the xDpi and yDpi fields of the Scrn-
InfoRec. The driver can specify preferred defaults by
setting x and y to non-zero values. The -dpi command
line option overrides all other settings. Otherwise, if
the DisplaySize entry is present in the screen's Monitor
config file section, it is used together with the virtual
size to calculate the dpi values. This function should
be called after all the mode resolution has been done.
void xf86SetBlackWhitePixels(ScrnInfoPtr pScrn)
This functions sets the blackPixel and whitePixel fields
of the ScrnInfoRec according to whether or not the -flip-
Pixels command line options is present.
const char *xf86GetVisualName(int visual)
Returns a printable string with the visual name matching
the numerical visual class provided. If the value is
outside the range of valid visual classes, NULL is
returned.
18.3 Primary Mode functions
The primary mode helper functions are those which would normally be used by a
driver, unless it has unusual requirements which cannot be catered for the by
the helpers.
int xf86ValidateModes(ScrnInfoPtr scrp, DisplayModePtr availModes,
char **modeNames, ClockRangePtr clockRanges,
int *linePitches, int minPitch, int maxPitch,
int pitchInc, int minHeight, int maxHeight,
int virtualX, int virtualY,
unsigned long apertureSize,
LookupModeFlags strategy)
This function basically selects the set of modes to use
based on those available and the various constraints. It
also sets some other related parameters. It is normally
called near the end of the ChipPreInit() function.
The parameters passed to the function are:
availModes
List of modes available for the monitor.
modeNames
List of mode names that the screen is request-
ing.
clockRanges
A list of clock ranges allowed by the driver.
Each range includes whether interlaced or mul-
tiscan modes are supported for that range. See
below for more on clockRanges.
linePitches
List of line pitches supported by the driver.
This is optional and should be NULL when not
used.
minPitch
Minimum line pitch supported by the driver.
This must be supplied when linePitches is NULL,
and is ignored otherwise.
maxPitch
Maximum line pitch supported by the driver.
This is required when minPitch is required.
pitchInc
Granularity of horizontal pitch values as sup-
ported by the chipset. This is expressed in
bits. This must be supplied.
minHeight
minimum virtual height allowed. If zero, no
limit is imposed.
maxHeight
maximum virtual height allowed. If zero, no
limit is imposed.
virtualX
If greater than zero, this is the virtual width
value that will be used. Otherwise, the vir-
tual width is chosen to be the smallest that
can accommodate the modes selected.
virtualY
If greater than zero, this is the virtual
height value that will be used. Otherwise, the
virtual height is chosen to be the smallest
that can accommodate the modes selected.
apertureSize
The size (in bytes) of the aperture used to
access video memory.
strategy
The strategy to use when choosing from multiple
modes with the same name. The options are:
LOOKUP_DEFAULT
???
LOOKUP_BEST_REFRESH
mode with best refresh rate
LOOKUP_CLOSEST_CLOCK
mode with closest matching clock
LOOKUP_LIST_ORDER
first usable mode in list
The following options can also be combined
(OR'ed) with one of the above:
LOOKUP_CLKDIV2
Allow halved clocks
LOOKUP_OPTIONAL_TOLERANCES
Allow missing horizontal sync and/or
vertical refresh ranges in the
XF86Config Monitor section
LOOKUP_OPTIONAL_TOLERANCES should only be spec-
ified when the driver can ensure all modes it
generates can sync on, or at least not damage,
the monitor or digital flat panel. Horizontal
sync and/or vertical refresh ranges specified
by the user will still be honoured (and acted
upon).
This function requires that the following fields of the
ScrnInfoRec are initialised prior to calling it:
clock[]
List of discrete clocks (when non-programmable)
numClocks
Number of discrete clocks (when non-pro-
grammable)
progClock
Whether the clock is programmable or not
monitor
Pointer to the applicable XF86Config monitor
section
fdFormat
Format of the screen buffer
videoRam
total video memory size (in bytes)
maxHValue
Maximum horizontal timing value allowed
maxVValue
Maximum vertical timing value allowed
xInc
Horizontal timing increment in pixels (defaults
to 8)
This function fills in the following ScrnInfoRec fields:
modePool
A subset of the modes available to the monitor
which are compatible with the driver.
modes
One mode entry for each of the requested modes,
with the status field of each filled in to
indicate if the mode has been accepted or not.
This list of modes is a circular list.
virtualX
The resulting virtual width.
virtualY
The resulting virtual height.
displayWidth
The resulting line pitch.
virtualFrom
Where the virtual size was determined from.
The first stage of this function checks that the virtualX
and virtualY values supplied (if greater than zero) are
consistent with the line pitch and maxHeight limitations.
If not, an error message is printed, and the return value
is -1.
The second stage sets up the mode pool, eliminating imme-
diately any modes that exceed the driver's line pitch
limits, and also the virtual width and height limits (if
greater than zero). For each mode removed an informa-
tional message is printed at verbosity level 2. If the
mode pool ends up being empty, a warning message is
printed, and the return value is 0.
The final stage is to lookup each mode name, and fill in
the remaining parameters. If an error condition is
encountered, a message is printed, and the return value
is -1. Otherwise, the return value is the number of
valid modes found (0 if none are found).
Even if the supplied mode names include duplicates, no
two names will ever match the same mode. Furthermore, if
the supplied mode names do not yield a valid mode
(including the case where no names are passed at all),
the function will continue looking through the mode pool
until it finds a mode that survives all checks, or until
the mode pool is exhausted.
A message is only printed by this function when a funda-
mental problem is found. It is intended that this func-
tion may be called more than once if there is more than
one set of constraints that the driver can work within.
If this function returns -1, the ChipPreInit() function
should return FALSE.
clockRanges is a linked list of clock ranges allowed by
the driver. If a mode doesn't fit in any of the defined
clockRanges, it is rejected. The first clockRange that
matches all requirements is used. This structure needs
to be initialized to NULL when allocated.
clockRanges contains the following fields:
minClock
maxClock
The lower and upper mode clock bounds for which
the rest of the clockRange parameters apply.
Since these are the mode clocks, they are not
scaled with the ClockMulFactor and ClockDivFac-
tor. It is up to the driver to adjust these
values if they depend on the clock scaling fac-
tors.
clockIndex
(not used yet) -1 for programmable clocks
interlaceAllowed
TRUE if interlacing is allowed for this range
doubleScanAllowed
TRUE if doublescan or multiscan is allowed for
this range
ClockMulFactor
ClockDivFactor
Scaling factors that are applied to the mode
clocks ONLY before selecting a clock index
(when there is no programmable clock) or a Syn-
thClock value. This is useful for drivers that
support pixel multiplexing or that need to
scale the clocks because of hardware restric-
tions (like sending 24bpp data to an 8 bit RAM-
DAC using a tripled clock).
Note that these parameters describe what must
be done to the mode clock to achieve the data
transport clock between graphics controller and
RAMDAC. For example for 2:1 pixel multiplex-
ing, two pixels are sent to the RAMDAC on each
clock. This allows the RAMDAC clock to be half
of the actual pixel clock. Hence, ClockMulFac-
tor=1 and ClockDivFactor=2. This means that
the clock used for clock selection (ie, deter-
mining the correct clock index from the list of
discrete clocks) or for the SynthClock field in
case of a programmable clock is: (mode->Clock
* ClockMulFactor) / ClockDivFactor.
PrivFlags
This field is copied into the mode->PrivFlags
field when this clockRange is selected by
xf86ValidateModes(). It allows the driver to
find out what clock range was selected, so it
knows it needs to set up pixel multiplexing or
any other range-dependent feature. This field
is purely driver-defined: it may contain flag
bits, an index or anything else (as long as it
is an INT).
Note that the mode->SynthClock field is always filled in
by xf86ValidateModes(): it will contain the ``data trans-
port clock'', which is the clock that will have to be
programmed in the chip when it has a programmable clock,
or the clock that will be picked from the clocks list
when it is not a programmable one. Thus:
mode->SynthClock =
(mode->Clock * ClockMulFactor) / ClockDivFactor
void xf86PruneDriverModes(ScrnInfoPtr scrp)
This function deletes modes in the modes field of the
ScrnInfoRec that have been marked as invalid. This is
normally run after having run xf86ValidateModes() for the
last time. For each mode that is deleted, a warning mes-
sage is printed out indicating the reason for it being
deleted.
void xf86SetCrtcForModes(ScrnInfoPtr scrp, int adjustFlags)
This function fills in the Crtc* fields for all the modes
in the modes field of the ScrnInfoRec. The adjustFlags
parameter determines how the vertical CRTC values are
scaled for interlaced modes. They are halved if it is
INTERLACE_HALVE_V. The vertical CRTC values are doubled
for doublescan modes, and are further multiplied by the
VScan value.
This function is normally called after calling
xf86PruneDriverModes().
void xf86PrintModes(ScrnInfoPtr scrp)
This function prints out the virtual size setting, and
the line pitch being used. It also prints out two lines
for each mode being used. The first line includes the
mode's pixel clock, horizontal sync rate, refresh rate,
and whether it is interlaced, doublescanned and/or multi-
scanned. The second line is the mode's Modeline.
This function is normally called after calling
xf86SetCrtcForModes().
18.4 Secondary Mode functions
The secondary mode helper functions are functions which are normally used by
the primary mode helper functions, and which are not normally called directly
by a driver. If a driver has unusual requirements and needs to do its own
mode validation, it might be able to make use of some of these secondary mode
helper functions.
int xf86GetNearestClock(ScrnInfoPtr scrp, int freq, Bool allowDiv2,
int *divider)
This function returns the index of the closest clock to
the frequency freq given (in kHz). It assumes that the
number of clocks is greater than zero. It requires that
the numClocks and clock fields of the ScrnInfoRec are
initialised. The allowDiv2 field determines if the
clocks can be halved. The *divider return value indi-
cates whether clock division is used when determining the
clock returned.
This function is only for non-programmable clocks.
const char *xf86ModeStatusToString(ModeStatus status)
This function converts the status value to a descriptive
printable string.
ModeStatus xf86LookupMode(ScrnInfoPtr scrp, DisplayModePtr modep,
ClockRangePtr clockRanges, LookupModeFlags strategy)
This function takes a pointer to a mode with the name
filled in, and looks for a mode in the modePool list
which matches. The parameters of the matching mode are
filled in to *modep. The clockRanges and strategy param-
eters are as for the xf86ValidateModes() function above.
This function requires the modePool, clock[], numClocks
and progClock fields of the ScrnInfoRec to be initialised
before being called.
The return value is MODE_OK if a mode was found. Other-
wise it indicates why a matching mode could not be found.
ModeStatus xf86InitialCheckModeForDriver(ScrnInfoPtr scrp,
DisplayModePtr mode, ClockRangePtr clockRanges,
LookupModeFlags strategy, int maxPitch,
int virtualX, int virtualY)
This function checks the passed mode against some basic
driver constraints. Apart from the ones passed explic-
itly, the maxHValue and maxVValue fields of the ScrnIn-
foRec are also used. If the ValidMode field of the Scrn-
InfoRec is set, that function is also called to check the
mode. Next, the mode is checked against the monitor's
constraints.
If the mode is consistent with all constraints, the
return value is MODE_OK. Otherwise the return value
indicates which constraint wasn't met.
void xf86DeleteMode(DisplayModePtr *modeList, DisplayModePtr mode)
This function deletes the mode given from the modeList.
It never prints any messages, so it is up to the caller
to print a message if required.
18.5 Functions for handling strings and tokens
Tables associating strings and numerical tokens combined with the following
functions provide a compact way of handling strings from the config file, and
for converting tokens into printable strings. The table data structure is:
typedef struct {
int token;
const char * name;
} SymTabRec, *SymTabPtr;
A table is an initialised array of SymTabRec. The tokens must be non-nega-
tive integers. Multiple names may be mapped to a single token. The table is
terminated with an element with a token value of -1 and NULL for the name.
const char *xf86TokenToString(SymTabPtr table, int token)
This function returns the first string in table that
matches token. If no match is found, NULL is returned
(NOTE, older versions of this function would return the
string "unknown" when no match is found).
int xf86StringToToken(SymTabPtr table, const char *string)
This function returns the first token in table that
matches string. The xf86NameCmp() function is used to
determine the match. If no match is found, -1 is
returned.
18.6 Functions for finding which config file entries to use
These functions can be used to select the appropriate config file entries
that match the detected hardware. They are described above in the Probe
(section 5.8, page 1) and Available Functions (section 9.3, page 1) sections.
18.7 Probing discrete clocks on old hardware
The xf86GetClocks() function may be used to assist in finding the discrete
pixel clock values on older hardware.
void xf86GetClocks(ScrnInfoPtr pScrn, int num,
Bool (*ClockFunc)(ScrnInfoPtr, int),
void (*ProtectRegs)(ScrnInfoPtr, Bool),
void (*BlankScreen)(ScrnInfoPtr, Bool),
int vertsyncreg, int maskval, int knownclkindex,
int knownclkvalue)
This function uses a comparative sampling method to mea-
sure the discrete pixel clock values. The number of dis-
crete clocks to measure is given by num. clockFunc is a
function that selects the n'th clock. It should also
save or restore any state affected by programming the
clocks when the index passed is CLK_REG_SAVE or
CLK_REG_RESTORE. ProtectRegs is a function that does
whatever is required to protect the hardware state while
selecting a new clock. BlankScreen is a function that
blanks the screen. vertsyncreg and maskval are the reg-
ister and bitmask to check for the presence of vertical
sync pulses. knownclkindex and knownclkvalue are the
index and value of a known clock. These are the known
references on which the comparative measurements are
based. The number of clocks probed is set in pScrn->num-
Clocks, and the probed clocks are set in the
pScrn->clock[] array. All of the clock values are in
units of kHz.
void xf86ShowClocks(ScrnInfoPtr scrp, MessageType from)
Print out the pixel clocks scrp->clock[]. from indicates
whether the clocks were probed or from the config file.
18.8 Other helper functions
Bool xf86IsUnblank(int mode)
Returns TRUE when the screen saver mode specified by mode
requires the screen be unblanked, and FALSE otherwise.
The screen saver modes that require blanking are
SCREEN_SAVER_ON and SCREEN_SAVER_CYCLE, and the screen
saver modes that require unblanking are SCREEN_SAVER_OFF
and SCREEN_SAVER_FORCER. Drivers may call this helper
from their SaveScreen() function to interpret the screen
saver modes.
19. The vgahw module
The vgahw modules provides an interface for saving, restoring and programming
the standard VGA registers, and for handling VGA colourmaps.
19.1 Data Structures
The public data structures used by the vgahw module are vgaRegRec and vgaH-
WRec. They are defined in vgaHW.h.
19.2 General vgahw Functions
Bool vgaHWGetHWRec(ScrnInfoPtr pScrn)
This function allocates a vgaHWRec structure, and hooks
it into the ScrnInfoRec's privates. Like all information
hooked into the privates, it is persistent, and only
needs to be allocated once per screen. This function
should normally be called from the driver's ChipPreInit()
function. The vgaHWRec is zero-allocated, and the fol-
lowing fields are explicitly initialised:
ModeReg.DAC[]
initialised with a default colourmap
ModeReg.Attribute[0x11]
initialised with the default overscan index
ShowOverscan
initialised according to the "ShowOverscan"
option
paletteEnabled
initialised to FALSE
cmapSaved
initialised to FALSE
pScrn
initialised to pScrn
In addition to the above, vgaHWSetStdFuncs() is called to
initialise the register access function fields with the
standard VGA set of functions.
Once allocated, a pointer to the vgaHWRec can be obtained
from the ScrnInfoPtr with the VGAHWPTR(pScrn) macro.
void vgaHWFreeHWRec(ScrnInfoPtr pScrn)
This function frees a vgaHWRec structure. It should be
called from a driver's ChipFreeScreen() function.
Bool vgaHWSetRegCounts(ScrnInfoPtr pScrn, int numCRTC,
int numSequencer, int numGraphics, int numAttribute)
This function allows the number of CRTC, Sequencer,
Graphics and Attribute registers to be changed. This
makes it possible for extended registers to be saved and
restored with vgaHWSave() and vgaHWRestore(). This func-
tion should be called after a vgaHWRec has been allocated
with vgaHWGetHWRec(). The default values are defined in
vgaHW.h as follows:
#define VGA_NUM_CRTC 25
#define VGA_NUM_SEQ 5
#define VGA_NUM_GFX 9
#define VGA_NUM_ATTR 21
Bool vgaHWCopyReg(vgaRegPtr dst, vgaRegPtr src)
This function copies the contents of the VGA saved regis-
ters in src to dst. Note that it isn't possible to sim-
ply do this with memcpy() (or similar). This function
returns TRUE unless there is a problem allocating space
for the CRTC and related fields in dst.
void vgaHWSetStdFuncs(vgaHWPtr hwp)
This function initialises the register access function
fields of hwp with the standard VGA set of functions.
This is called by vgaHWGetHWRec(), so there is usually no
need to call this explicitly. The register access func-
tions are described below. If the registers are shadowed
in some other port I/O space (for example a PCI I/O
region), these functions can be used to access the shad-
owed registers if hwp->PIOOffset is initialised with off-
set, calculated in such a way that when the standard VGA
I/O port value is added to it the correct offset into the
PIO area results. This value is initialised to zero in
vgaHWGetHWRec(). (Note: the PIOOffset functionality is
present in XFree86 4.1.0 and later.)
void vgaHWSetMmioFuncs(vgaHWPtr hwp, CARD8 *base, int offset)
This function initialised the register access function
fields of hwp with a generic MMIO set of functions.
hwp->MMIOBase is initialised with base, which must be the
virtual address that the start of MMIO area is mapped to.
hwp->MMIOOffset is initialised with offset, which must be
calculated in such a way that when the standard VGA I/O
port value is added to it the correct offset into the
MMIO area results. That means that these functions are
only suitable when the VGA I/O ports are made available
in a direct mapping to the MMIO space. If that is not
the case, the driver will need to provide its own regis-
ter access functions. The register access functions are
described below.
Bool vgaHWMapMem(ScrnInfoPtr pScrn)
This function maps the VGA memory window. It requires
that the vgaHWRec be allocated. If a driver requires
non-default MapPhys or MapSize settings (the physical
location and size of the VGA memory window) then those
fields of the vgaHWRec must be initialised before calling
this function. Otherwise, this function initialiases the
default values of 0xA0000 for MapPhys and (64 * 1024) for
MapSize. This function must be called before attempting
to save or restore the VGA state. If the driver doesn't
call it explicitly, the vgaHWSave() and vgaHWRestore()
functions may call it if they need to access the VGA mem-
ory (in which case they will also call vgaHWUnmapMem() to
unmap the VGA memory before exiting).
void vgaHWUnmapMem(ScrnInfoPtr pScrn)
This function unmaps the VGA memory window. It must only
be called after the memory has been mapped. The Base
field of the vgaHWRec field is set to NULL to indicate
that the memory is no longer mapped.
void vgaHWGetIOBase(vgaHWPtr hwp)
This function initialises the IOBase field of the vgaH-
WRec. This function must be called before using any
other functions that access the video hardware.
A macro VGAHW_GET_IOBASE() is also available in vgaHW.h
that returns the I/O base, and this may be used when the
vgahw module is not loaded (for example, in the Chip-
Probe() function).
void vgaHWUnlock(vgaHWPtr hwp)
This function unlocks the VGA CRTC[0-7] registers, and
must be called before attempting to write to those regis-
ters.
void vgaHWLock(vgaHWPtr hwp)
This function locks the VGA CRTC[0-7] registers.
void vgaHWEnable(vgaHWPtr hwp)
This function enables the VGA subsystem. (Note, this
function is present in XFree86 4.1.0 and later.).
void vgaHWDisable(vgaHWPtr hwp)
This function disables the VGA subsystem. (Note, this
function is present in XFree86 4.1.0 and later.).
void vgaHWSave(ScrnInfoPtr pScrn, vgaRegPtr save, int flags)
This function saves the VGA state. The state is written
to the vgaRegRec pointed to by save. flags is set to one
or more of the following flags ORed together:
VGA_SR_MODE
the mode setting registers are saved
VGA_SR_FONTS
the text mode font/text data is saved
VGA_SR_CMAP
the colourmap (LUT) is saved
VGA_SR_ALL
all of the above are saved
The vgaHWRec and its IOBase fields must be initialised
before this function is called. If VGA_SR_FONTS is set
in flags, the VGA memory window must be mapped. If it
isn't then vgaHWMapMem() will be called to map it, and
vgaHWUnmapMem() will be called to unmap it afterwards.
vgaHWSave() uses the three functions below in the order
vgaHWSaveColormap(), vgaHWSaveMode(), vgaHWSaveFonts() to
carry out the different save phases. It is undecided at
this stage whether they will remain part of the vgahw
module's public interface or not.
void vgaHWSaveMode(ScrnInfoPtr pScrn, vgaRegPtr save)
This function saves the VGA mode registers. They are
saved to the vgaRegRec pointed to by save. The registers
saved are:
MiscOut
CRTC[0-0x18]
Attribute[0-0x14]
Graphics[0-8]
Sequencer[0-4]
The number of registers actually saved may be modified by
a prior call to vgaHWSetRegCounts().
void vgaHWSaveFonts(ScrnInfoPtr pScrn, vgaRegPtr save)
This function saves the text mode font and text data held
in the video memory. If called while in a graphics mode,
no save is done. The VGA memory window must be mapped
with vgaHWMapMem() before to calling this function.
On some platforms, one or more of the font/text plane
saves may be no-ops. This is the case when the plat-
form's VC driver already takes care of this.
void vgaHWSaveColormap(ScrnInfoPtr pScrn, vgaRegPtr save)
This function saves the VGA colourmap (LUT). Before sav-
ing it, it attempts to verify that the colourmap is read-
able. In rare cases where it isn't readable, a default
colourmap is saved instead.
void vgaHWRestore(ScrnInfoPtr pScrn, vgaRegPtr restore, int flags)
This function programs the VGA state. The state pro-
grammed is that contained in the vgaRegRec pointed to by
restore. flags is the same as described above for the
vgaHWSave() function.
The vgaHWRec and its IOBase fields must be initialised
before this function is called. If VGA_SR_FONTS is set
in flags, the VGA memory window must be mapped. If it
isn't then vgaHWMapMem() will be called to map it, and
vgaHWUnmapMem() will be called to unmap it afterwards.
vgaHWRestore() uses the three functions below in the
order vgaHWRestoreFonts(), vgaHWRestoreMode(), vgaHWRe-
storeColormap() to carry out the different restore
phases. It is undecided at this stage whether they will
remain part of the vgahw module's public interface or
not.
void vgaHWRestoreMode(ScrnInfoPtr pScrn, vgaRegPtr restore)
This function restores the VGA mode registers. They are
restored from the data in the vgaRegRec pointed to by
restore. The registers restored are:
MiscOut
CRTC[0-0x18]
Attribute[0-0x14]
Graphics[0-8]
Sequencer[0-4]
The number of registers actually restored may be modified
by a prior call to vgaHWSetRegCounts().
void vgaHWRestoreFonts(ScrnInfoPtr pScrn, vgaRegPtr restore)
This function restores the text mode font and text data
to the video memory. The VGA memory window must be
mapped with vgaHWMapMem() before to calling this func-
tion.
On some platforms, one or more of the font/text plane
restores may be no-ops. This is the case when the plat-
form's VC driver already takes care of this.
void vgaHWRestoreColormap(ScrnInfoPtr pScrn, vgaRegPtr restore)
This function restores the VGA colourmap (LUT).
void vgaHWInit(ScrnInfoPtr pScrn, DisplayModePtr mode)
This function fills in the vgaHWRec's ModeReg field with
the values appropriate for programming the given video
mode. It requires that the ScrnInfoRec's depth field is
initialised, which determines how the registers are pro-
grammed.
void vgaHWSeqReset(vgaHWPtr hwp, Bool start)
Do a VGA sequencer reset. If start is TRUE, the reset is
started. If start is FALSE, the reset is ended.
void vgaHWProtect(ScrnInfoPtr pScrn, Bool on)
This function protects VGA registers and memory from cor-
ruption during loads. It is typically called with on set
to TRUE before programming, and with on set to FALSE
after programming.
Bool vgaHWSaveScreen(ScreenPtr pScreen, int mode)
This function blanks and unblanks the screen. It is
blanked when mode is SCREEN_SAVER_ON or
SCREEN_SAVER_CYCLE, and unblanked when mode is
SCREEN_SAVER_OFF or SCREEN_SAVER_FORCER.
void vgaHWBlankScreen(ScrnInfoPtr pScrn, Bool on)
This function blanks and unblanks the screen. It is
blanked when on is FALSE, and unblanked when on is TRUE.
This function is provided for use in cases where the
ScrnInfoRec can't be derived from the ScreenRec (while
probing for clocks, for example).
19.3 VGA Colormap Functions
The vgahw module uses the standard colormap support (see the Colormap Han-
dling (section 13., page 1) section. This is initialised with the following
function:
Bool vgaHWHandleColormaps(ScreenPtr pScreen)
19.4 VGA Register Access Functions
The vgahw module abstracts access to the standard VGA registers by using a
set of functions held in the vgaHWRec. When the vgaHWRec is created these
function pointers are initialised with the set of standard VGA I/O register
access functions. In addition to these, the vgahw module includes a basic
set of MMIO register access functions, and the vgaHWRec function pointers can
be initialised to these by calling the vgaHWSetMmioFuncs() function described
above. Some drivers/platforms may require a different set of functions for
VGA access. The access functions are described here.
void writeCrtc(vgaHWPtr hwp, CARD8 index, CARD8 value)
Write value to CRTC register index.
CARD8 readCrtc(vgaHWPtr hwp, CARD8 index)
Return the value read from CRTC register index.
void writeGr(vgaHWPtr hwp, CARD8 index, CARD8 value)
Write value to Graphics Controller register index.
CARD8 readGR(vgaHWPtr hwp, CARD8 index)
Return the value read from Graphics Controller register
index.
void writeSeq(vgaHWPtr hwp, CARD8 index, CARD8, value)
Write value to Sequencer register index.
CARD8 readSeq(vgaHWPtr hwp, CARD8 index)
Return the value read from Sequencer register index.
void writeAttr(vgaHWPtr hwp, CARD8 index, CARD8, value)
Write value to Attribute Controller register index. When
writing out the index value this function should set bit
5 (0x20) according to the setting of hwp->paletteEnabled
in order to preserve the palette access state. It should
be cleared when hwp->paletteEnabled is TRUE and set when
it is FALSE.
CARD8 readAttr(vgaHWPtr hwp, CARD8 index)
Return the value read from Attribute Controller register
index. When writing out the index value this function
should set bit 5 (0x20) according to the setting of
hwp->paletteEnabled in order to preserve the palette
access state. It should be cleared when hwp->paletteEn-
abled is TRUE and set when it is FALSE.
void writeMiscOut(vgaHWPtr hwp, CARD8 value)
Write `value' to the Miscellaneous Output register.
CARD8 readMiscOut(vgwHWPtr hwp)
Return the value read from the Miscellaneous Output reg-
ister.
void enablePalette(vgaHWPtr hwp)
Clear the palette address source bit in the Attribute
Controller index register and set hwp->paletteEnabled to
TRUE.
void disablePalette(vgaHWPtr hwp)
Set the palette address source bit in the Attribute Con-
troller index register and set hwp->paletteEnabled to
FALSE.
void writeDacMask(vgaHWPtr hwp, CARD8 value)
Write value to the DAC Mask register.
CARD8 readDacMask(vgaHWptr hwp)
Return the value read from the DAC Mask register.
void writeDacReadAddress(vgaHWPtr hwp, CARD8 value)
Write value to the DAC Read Address register.
void writeDacWriteAddress(vgaHWPtr hwp, CARD8 value)
Write value to the DAC Write Address register.
void writeDacData(vgaHWPtr hwp, CARD8 value)
Write value to the DAC Data register.
CARD8 readDacData(vgaHWptr hwp)
Return the value read from the DAC Data register.
CARD8 readEnable(vgaHWptr hwp)
Return the value read from the VGA Enable register.
(Note: This function is present in XFree86 4.1.0 and
later.)
void writeEnable(vgaHWPtr hwp, CARD8 value)
Write value to the VGA Enable register. (Note: This
function is present in XFree86 4.1.0 and later.)
20. Some notes about writing a driver
NOTE: some parts of this are not up to date
The following is an outline for writing a basic unaccelerated driver for a
PCI video card with a linear mapped framebuffer, and which has a VGA core.
It is includes some general information that is relevant to most drivers
(even those which don't fit that basic description).
The information here is based on the initial conversion of the Matrox Millen-
nium driver to the ``new design''. For a fleshing out and sample implementa-
tion of some of the bits outlined here, refer to that driver. Note that this
is an example only. The approach used here will not be appropriate for all
drivers.
Each driver must reserve a unique driver name, and a string that is used to
prefix all of its externally visible symbols. This is to avoid name space
clashes when loading multiple drivers. The examples here are for the ``ZZZ''
driver, which uses the ``ZZZ'' or ``zzz'' prefix for its externally visible
symbols.
20.1 Include files
All drivers normally include the following headers:
"xf86.h"
"xf86_OSproc.h"
"xf86_ansic.h"
"xf86Resources.h"
Wherever inb/outb (and related things) are used the following should be
included:
"compiler.h"
Note: in drivers, this must be included after "xf86_ansic.h".
Drivers that need to access PCI vendor/device definitions need this:
"xf86PciInfo.h"
Drivers that need to access the PCI config space need this:
"xf86Pci.h"
Drivers using the mi banking wrapper need:
"mibank.h"
Drivers that initialise a SW cursor need this:
"mipointer.h"
All drivers implementing backing store need this:
"mibstore.h"
All drivers using the mi colourmap code need this:
"micmap.h"
If a driver uses the vgahw module, it needs this:
"vgaHW.h"
Drivers supporting VGA or Hercules monochrome screens need:
"xf1bpp.h"
Drivers supporting VGA or EGC 16-colour screens need:
"xf4bpp.h"
Drivers using cfb need:
#define PSZ 8
#include "cfb.h"
#undef PSZ
Drivers supporting bpp 16, 24 or 32 with cfb need one or more of:
"cfb16.h"
"cfb24.h"
"cfb32.h"
The driver's own header file:
"zzz.h"
Drivers must NOT include the following:
"xf86Priv.h"
"xf86Privstr.h"
"xf86_libc.h"
"xf86_OSlib.h"
"Xos.h"
any OS header
20.2 Data structures and initialisation
o The following macros should be defined:
#define VERSION <version-as-an-int>
#define ZZZ_NAME "ZZZ" /* the name used to prefix messages */
#define ZZZ_DRIVER_NAME "zzz" /* the driver name as used in config file */
#define ZZZ_MAJOR_VERSION <int>
#define ZZZ_MINOR_VERSION <int>
#define ZZZ_PATCHLEVEL <int>
NOTE: ZZZ_DRIVER_NAME should match the name of the driver module without
things like the "lib" prefix, the "_drv" suffix or filename extensions.
o A DriverRec must be defined, which includes the functions required at
the pre-probe phase. The name of this DriverRec must be an upper-case
version of ZZZ_DRIVER_NAME (for the purposes of static linking).
DriverRec ZZZ = {
VERSION,
ZZZ_DRIVER_NAME,
ZZZIdentify,
ZZZProbe,
ZZZAvailableOptions,
NULL,
0
};
o Define list of supported chips and their matching ID:
static SymTabRec ZZZChipsets[] = {
{ PCI_CHIP_ZZZ1234, "zzz1234a" },
{ PCI_CHIP_ZZZ5678, "zzz5678a" },
{ -1, NULL }
};
The token field may be any integer value that the driver may use to
uniquely identify the supported chipsets. For drivers that support only
PCI devices using the PCI device IDs might be a natural choice, but this
isn't mandatory. For drivers that support both PCI and other devices
(like ISA), some other ID should probably used. When other IDs are used
as the tokens it is recommended that the names be defined as an enum
type.
o If the driver uses the xf86MatchPciInstances() helper (recommended for
drivers that support PCI cards) a list that maps PCI IDs to chip IDs and
fixed resources must be defined:
static PciChipsets ZZZPciChipsets[] = {
{ PCI_CHIP_ZZZ1234, PCI_CHIP_ZZZ1234, RES_SHARED_VGA },
{ PCI_CHIP_ZZZ5678, PCI_CHIP_ZZZ5678, RES_SHARED_VGA },
{ -1, -1, RES_UNDEFINED }
}
o Define the XF86ModuleVersionInfo struct for the driver. This is
required for the dynamically loaded version:
#ifdef XFree86LOADER
static XF86ModuleVersionInfo zzzVersRec =
{
"zzz",
MODULEVENDORSTRING,
MODINFOSTRING1,
MODINFOSTRING2,
XF86_VERSION_CURRENT,
ZZZ_MAJOR_VERSION, ZZZ_MINOR_VERSION, ZZZ_PATCHLEVEL,
ABI_CLASS_VIDEODRV,
ABI_VIDEODRV_VERSION,
MOD_CLASS_VIDEODRV,
{0,0,0,0}
};
#endif
o Define a data structure to hold the driver's screen-specific data. This
must be used instead of global variables. This would be defined in the
"zzz.h" file, something like:
typedef struct {
type1 field1;
type2 field2;
int fooHack;
Bool pciRetry;
Bool noAccel;
Bool hwCursor;
CloseScreenProcPtr CloseScreen;
OptionInfoPtr Options;
...
} ZZZRec, *ZZZPtr;
o Define the list of config file Options that the driver accepts. For
consistency between drivers those in the list of ``standard'' options
should be used where appropriate before inventing new options.
typedef enum {
OPTION_FOO_HACK,
OPTION_PCI_RETRY,
OPTION_HW_CURSOR,
OPTION_NOACCEL
} ZZZOpts;
static const OptionInfoRec ZZZOptions[] = {
{ OPTION_FOO_HACK, "FooHack", OPTV_INTEGER, {0}, FALSE },
{ OPTION_PCI_RETRY, "PciRetry", OPTV_BOOLEAN, {0}, FALSE },
{ OPTION_HW_CURSOR, "HWcursor", OPTV_BOOLEAN, {0}, FALSE },
{ OPTION_NOACCEL, "NoAccel", OPTV_BOOLEAN, {0}, FALSE },
{ -1, NULL, OPTV_NONE, {0}, FALSE }
};
20.3 Functions
20.3.1 SetupProc
For dynamically loaded modules, a ModuleData variable is required. It is
should be the name of the driver prepended to "ModuleData". A Setup() func-
tion is also required, which calls xf86AddDriver() to add the driver to the
main list of drivers.
#ifdef XFree86LOADER
static MODULESETUPPROTO(mgaSetup);
XF86ModuleData zzzModuleData = { &zzzVersRec, zzzSetup, NULL };
static pointer
zzzSetup(pointer module, pointer opts, int *errmaj, int *errmin)
{
static Bool setupDone = FALSE;
/* This module should be loaded only once, but check to be sure. */
if (!setupDone) {
/*
* Modules that this driver always requires may be loaded
* here by calling LoadSubModule().
*/
setupDone = TRUE;
xf86AddDriver(&MGA, module, 0);
/*
* The return value must be non-NULL on success even though
* there is no TearDownProc.
*/
return (pointer)1;
} else {
if (errmaj) *errmaj = LDR_ONCEONLY;
return NULL;
}
}
#endif
20.3.2 GetRec, FreeRec
A function is usually required to allocate the driver's screen-specific data
structure and hook it into the ScrnInfoRec's driverPrivate field. The Scrn-
InfoRec's driverPrivate is initialised to NULL, so it is easy to check if the
initialisation has already been done. After allocating it, initialise the
fields. By using xnfcalloc() to do the allocation it is zeroed, and if the
allocation fails the server exits.
NOTE: When allocating structures from inside the driver which are defined on
the common level it is important to initialize the structure to zero. Only
this guarantees that the server remains source compatible to future changes
in common level structures.
static Bool
ZZZGetRec(ScrnInfoPtr pScrn)
{
if (pScrn->driverPrivate != NULL)
return TRUE;
pScrn->driverPrivate = xnfcalloc(sizeof(ZZZRec), 1);
/* Initialise as required */
...
return TRUE;
}
Define a macro in "zzz.h" which gets a pointer to the ZZZRec when given
pScrn:
#define ZZZPTR(p) ((ZZZPtr)((p)->driverPrivate))
Define a function to free the above, setting it to NULL once it has been
freed:
static void
ZZZFreeRec(ScrnInfoPtr pScrn)
{
if (pScrn->driverPrivate == NULL)
return;
xfree(pScrn->driverPrivate);
pScrn->driverPrivate = NULL;
}
20.3.3 Identify
Define the Identify() function. It is run before the Probe, and typically
prints out an identifying message, which might include the chipsets it sup-
ports. This function is mandatory:
static void
ZZZIdentify(int flags)
{
xf86PrintChipsets(ZZZ_NAME, "driver for ZZZ Tech chipsets",
ZZZChipsets);
}
20.3.4 Probe
Define the Probe() function. The purpose of this is to find all instances of
the hardware that the driver supports, and for the ones not already claimed
by another driver, claim the slot, and allocate a ScrnInfoRec. This should
be a minimal probe, and it should under no circumstances leave the state of
the hardware changed. Because a device is found, don't assume that it will
be used. Don't do any initialisations other than the required ScrnInfoRec
initialisations. Don't allocate any new data structures.
This function is mandatory.
NOTE: The xf86DrvMsg() functions cannot be used from the Probe.
static Bool
ZZZProbe(DriverPtr drv, int flags)
{
Bool foundScreen = FALSE;
int numDevSections, numUsed;
GDevPtr *devSections;
int *usedChips;
int i;
/*
* Find the config file Device sections that match this
* driver, and return if there are none.
*/
if ((numDevSections = xf86MatchDevice(ZZZ_DRIVER_NAME,
&devSections)) <= 0) {
return FALSE;
}
/*
* Since this is a PCI card, "probing" just amounts to checking
* the PCI data that the server has already collected. If there
* is none, return.
*
* Although the config file is allowed to override things, it
* is reasonable to not allow it to override the detection
* of no PCI video cards.
*
* The provided xf86MatchPciInstances() helper takes care of
* the details.
*/
/* test if PCI bus present */
if (xf86GetPciVideoInfo()) {
numUsed = xf86MatchPciInstances(ZZZ_NAME, PCI_VENDOR_ZZZ,
ZZZChipsets, ZZZPciChipsets, devSections,
numDevSections, drv, &usedChips);
for (i = 0; i < numUsed; i++) {
ScrnInfoPtr pScrn = NULL;
if ((pScrn = xf86ConfigPciEntity(pScrn, flags, usedChips[i],
ZZZPciChipsets, NULL, NULL,
NULL, NULL, NULL))) {
/* Allocate a ScrnInfoRec */
pScrn->driverVersion = VERSION;
pScrn->driverName = ZZZ_DRIVER_NAME;
pScrn->name = ZZZ_NAME;
pScrn->Probe = ZZZProbe;
pScrn->PreInit = ZZZPreInit;
pScrn->ScreenInit = ZZZScreenInit;
pScrn->SwitchMode = ZZZSwitchMode;
pScrn->AdjustFrame = ZZZAdjustFrame;
pScrn->EnterVT = ZZZEnterVT;
pScrn->LeaveVT = ZZZLeaveVT;
pScrn->FreeScreen = ZZZFreeScreen;
pScrn->ValidMode = ZZZValidMode;
foundScreen = TRUE;
/* add screen to entity */
}
}
xfree(usedChips);
}
#ifdef HAS_ISA_DEVS
/*
* If the driver supports ISA hardware, the following block
* can be included too.
*/
numUsed = xf86MatchIsaInstances(ZZZ_NAME, ZZZChipsets,
ZZZIsaChipsets, drv, ZZZFindIsaDevice,
devSections, numDevSections, &usedChips);
for (i = 0; i < numUsed; i++) {
ScrnInfoPtr pScrn = NULL;
if ((pScrn = xf86ConfigIsaEntity(pScrn, flags, usedChips[i],
ZZZIsaChipsets, NULL, NULL, NULL,
NULL, NULL))) {
pScrn->driverVersion = VERSION;
pScrn->driverName = ZZZ_DRIVER_NAME;
pScrn->name = ZZZ_NAME;
pScrn->Probe = ZZZProbe;
pScrn->PreInit = ZZZPreInit;
pScrn->ScreenInit = ZZZScreenInit;
pScrn->SwitchMode = ZZZSwitchMode;
pScrn->AdjustFrame = ZZZAdjustFrame;
pScrn->EnterVT = ZZZEnterVT;
pScrn->LeaveVT = ZZZLeaveVT;
pScrn->FreeScreen = ZZZFreeScreen;
pScrn->ValidMode = ZZZValidMode;
foundScreen = TRUE;
}
}
xfree(usedChips);
#endif /* HAS_ISA_DEVS */
xfree(devSections);
return foundScreen;
20.3.5 AvailableOptions
Define the AvailableOptions() function. The purpose of this is to return the
available driver options back to the -configure option, so that an XF86Config
file can be built and the user can see which options are available for them
to use.
20.3.6 PreInit
Define the PreInit() function. The purpose of this is to find all the infor-
mation required to determine if the configuration is usable, and to ini-
tialise those parts of the ScrnInfoRec that can be set once at the beginning
of the first server generation. The information should be found in the least
intrusive way possible.
This function is mandatory.
NOTES:
1. The PreInit() function is only called once during the life of the X
server (at the start of the first generation).
2. Data allocated here must be of the type that persists for the life of
the X server. This means that data that hooks into the ScrnInfoRec's
privates field should be allocated here, but data that hooks into the
ScreenRec's devPrivates field should not be allocated here. The
driverPrivate field should also be allocated here.
3. Although the ScrnInfoRec has been allocated before this function is
called, the ScreenRec has not been allocated. That means that things
requiring it cannot be used in this function.
4. Very little of the ScrnInfoRec has been initialised when this function
is called. It is important to get the order of doing things right in
this function.
static Bool
ZZZPreInit(ScrnInfoPtr pScrn, int flags)
{
/* Fill in the monitor field */
pScrn->monitor = pScrn->confScreen->monitor;
/*
* If using the vgahw module, it will typically be loaded
* here by calling xf86LoadSubModule(pScrn, "vgahw");
*/
/*
* Set the depth/bpp. Use the globally preferred depth/bpp. If the
* driver has special default depth/bpp requirements, the defaults should
* be specified here explicitly.
* We support both 24bpp and 32bpp framebuffer layouts.
* This sets pScrn->display also.
*/
if (!xf86SetDepthBpp(pScrn, 0, 0, 0,
Support24bppFb | Support32bppFb)) {
return FALSE;
} else {
if (depth/bpp isn't one we support) {
print error message;
return FALSE;
}
}
/* Print out the depth/bpp that was set */
xf86PrintDepthBpp(pScrn);
/* Set bits per RGB for 8bpp */
if (pScrn->depth <= 8) {
/* Take into account a dac_6_bit option here */
pScrn->rgbBits = 6 or 8;
}
/*
* xf86SetWeight() and xf86SetDefaultVisual() must be called
* after pScrn->display is initialised.
*/
/* Set weight/mask/offset for depth > 8 */
if (pScrn->depth > 8) {
if (!xf86SetWeight(pScrn, defaultWeight, defaultMask)) {
return FALSE;
} else {
if (weight isn't one we support) {
print error message;
return FALSE;
}
}
}
/* Set the default visual. */
if (!xf86SetDefaultVisual(pScrn, -1)) {
return FALSE;
} else {
if (visual isn't one we support) {
print error message;
return FALSE;
}
}
/* If the driver supports gamma correction, set the gamma. */
if (!xf86SetGamma(pScrn, default_gamma)) {
return FALSE;
}
/* This driver uses a programmable clock */
pScrn->progClock = TRUE;
/* Allocate the ZZZRec driverPrivate */
if (!ZZZGetRec(pScrn)) {
return FALSE;
}
pZzz = ZZZPTR(pScrn);
/* Collect all of the option flags (fill in pScrn->options) */
xf86CollectOptions(pScrn, NULL);
/*
* Process the options based on the information in ZZZOptions.
* The results are written to pZzz->Options. If all of the options
* processing is done within this function a local variable "options"
* can be used instead of pZzz->Options.
*/
if (!(pZzz->Options = xalloc(sizeof(ZZZOptions))))
return FALSE;
(void)memcpy(pZzz->Options, ZZZOptions, sizeof(ZZZOptions));
xf86ProcessOptions(pScrn->scrnIndex, pScrn->options, pZzz->Options);
/*
* Set various fields of ScrnInfoRec and/or ZZZRec based on
* the options found.
*/
from = X_DEFAULT;
pZzz->hwCursor = FALSE;
if (xf86IsOptionSet(pZzz->Options, OPTION_HW_CURSOR)) {
from = X_CONFIG;
pZzz->hwCursor = TRUE;
}
xf86DrvMsg(pScrn->scrnIndex, from, "Using %s cursor\n",
pZzz->hwCursor ? "HW" : "SW");
if (xf86IsOptionSet(pZzz->Options, OPTION_NOACCEL)) {
pZzz->noAccel = TRUE;
xf86DrvMsg(pScrn->scrnIndex, X_CONFIG,
"Acceleration disabled\n");
} else {
pZzz->noAccel = FALSE;
}
if (xf86IsOptionSet(pZzz->Options, OPTION_PCI_RETRY)) {
pZzz->UsePCIRetry = TRUE;
xf86DrvMsg(pScrn->scrnIndex, X_CONFIG, "PCI retry enabled\n");
}
pZzz->fooHack = 0;
if (xf86GetOptValInteger(pZzz->Options, OPTION_FOO_HACK,
&pZzz->fooHack)) {
xf86DrvMsg(pScrn->scrnIndex, X_CONFIG, "Foo Hack set to %d\n",
pZzz->fooHack);
}
/*
* Find the PCI slot(s) that this screen claimed in the probe.
* In this case, exactly one is expected, so complain otherwise.
* Note in this case we're not interested in the card types so
* that parameter is set to NULL.
*/
if ((i = xf86GetPciInfoForScreen(pScrn->scrnIndex, &pciList, NULL))
!= 1) {
print error message;
ZZZFreeRec(pScrn);
if (i > 0)
xfree(pciList);
return FALSE;
}
/* Note that pciList should be freed below when no longer needed */
/*
* Determine the chipset, allowing config file chipset and
* chipid values to override the probed information. The config
* chipset value has precedence over its chipid value if both
* are present.
*
* It isn't necessary to fill in pScrn->chipset if the driver
* keeps track of the chipset in its ZZZRec.
*/
...
/*
* Determine video memory, fb base address, I/O addresses, etc,
* allowing the config file to override probed values.
*
* Set the appropriate pScrn fields (videoRam is probably the
* most important one that other code might require), and
* print out the settings.
*/
...
/* Initialise a clockRanges list. */
...
/* Set any other chipset specific things in the ZZZRec */
...
/* Select valid modes from those available */
i = xf86ValidateModes(pScrn, pScrn->monitor->Modes,
pScrn->display->modes, clockRanges,
NULL, minPitch, maxPitch, rounding,
minHeight, maxHeight,
pScrn->display->virtualX,
pScrn->display->virtualY,
pScrn->videoRam * 1024,
LOOKUP_BEST_REFRESH);
if (i == -1) {
ZZZFreeRec(pScrn);
return FALSE;
}
/* Prune the modes marked as invalid */
xf86PruneDriverModes(pScrn);
/* If no valid modes, return */
if (i == 0 || pScrn->modes == NULL) {
print error message;
ZZZFreeRec(pScrn);
return FALSE;
}
/*
* Initialise the CRTC fields for the modes. This driver expects
* vertical values to be halved for interlaced modes.
*/
xf86SetCrtcForModes(pScrn, INTERLACE_HALVE_V);
/* Set the current mode to the first in the list. */
pScrn->currentMode = pScrn->modes;
/* Print the list of modes being used. */
xf86PrintModes(pScrn);
/* Set the DPI */
xf86SetDpi(pScrn, 0, 0);
/* Load bpp-specific modules */
switch (pScrn->bitsPerPixel) {
case 1:
mod = "xf1bpp";
break;
case 4:
mod = "xf4bpp";
break;
case 8:
mod = "cfb";
break;
case 16:
mod = "cfb16";
break;
case 24:
mod = "cfb24";
break;
case 32:
mod = "cfb32";
break;
}
if (mod && !xf86LoadSubModule(pScrn, mod))
ZZZFreeRec(pScrn);
return FALSE;
/* Load XAA if needed */
if (!pZzz->noAccel || pZzz->hwCursor)
if (!xf86LoadSubModule(pScrn, "xaa")) {
ZZZFreeRec(pScrn);
return FALSE;
}
/* Done */
return TRUE;
}
20.3.7 MapMem, UnmapMem
Define functions to map and unmap the video memory and any other memory aper-
tures required. These functions are not mandatory, but it is often useful to
have such functions.
static Bool
ZZZMapMem(ScrnInfoPtr pScrn)
{
/* Call xf86MapPciMem() to map each PCI memory area */
...
return TRUE or FALSE;
}
static Bool
ZZZUnmapMem(ScrnInfoPtr pScrn)
{
/* Call xf86UnMapVidMem() to unmap each memory area */
...
return TRUE or FALSE;
}
20.3.8 Save, Restore
Define functions to save and restore the original video state. These func-
tions are not mandatory, but are often useful.
static void
ZZZSave(ScrnInfoPtr pScrn)
{
/*
* Save state into per-screen data structures.
* If using the vgahw module, vgaHWSave will typically be
* called here.
*/
...
}
static void
ZZZRestore(ScrnInfoPtr pScrn)
{
/*
* Restore state from per-screen data structures.
* If using the vgahw module, vgaHWRestore will typically be
* called here.
*/
...
}
20.3.9 ModeInit
Define a function to initialise a new video mode. This function isn't manda-
tory, but is often useful.
static Bool
ZZZModeInit(ScrnInfoPtr pScrn, DisplayModePtr mode)
{
/*
* Program a video mode. If using the vgahw module,
* vgaHWInit and vgaRestore will typically be called here.
* Once up to the point where there can't be a failure
* set pScrn->vtSema to TRUE.
*/
...
}
20.3.10 ScreenInit
Define the ScreenInit() function. This is called at the start of each server
generation, and should fill in as much of the ScreenRec as possible as well
as any other data that is initialised once per generation. It should ini-
tialise the framebuffer layers it is using, and initialise the initial video
mode.
This function is mandatory.
NOTE: The ScreenRec (pScreen) is passed to this driver, but it and the Scrn-
InfoRecs are not yet hooked into each other. This means that in this func-
tion, and functions it calls, one cannot be found from the other.
static Bool
ZZZScreenInit(int scrnIndex, ScreenPtr pScreen, int argc, char **argv)
{
/* Get the ScrnInfoRec */
pScrn = xf86Screens[pScreen->myNum];
/*
* If using the vgahw module, its data structures and related
* things are typically initialised/mapped here.
*/
/* Save the current video state */
ZZZSave(pScrn);
/* Initialise the first mode */
ZZZModeInit(pScrn, pScrn->currentMode);
/* Set the viewport if supported */
ZZZAdjustFrame(scrnIndex, pScrn->frameX0, pScrn->frameY0, 0);
/*
* Setup the screen's visuals, and initialise the framebuffer
* code.
*/
/* Reset the visual list */
miClearVisualTypes();
/*
* Setup the visuals supported. This driver only supports
* TrueColor for bpp > 8, so the default set of visuals isn't
* acceptable. To deal with this, call miSetVisualTypes with
* the appropriate visual mask.
*/
if (pScrn->bitsPerPixel > 8) {
if (!miSetVisualTypes(pScrn->depth, TrueColorMask,
pScrn->rgbBits, pScrn->defaultVisual))
return FALSE;
} else {
if (!miSetVisualTypes(pScrn->depth,
miGetDefaultVisualMask(pScrn->depth),
pScrn->rgbBits, pScrn->defaultVisual))
return FALSE;
}
/*
* Initialise the framebuffer.
*/
switch (pScrn->bitsPerPixel) {
case 1:
ret = xf1bppScreenInit(pScreen, FbBase,
pScrn->virtualX, pScrn->virtualY,
pScrn->xDpi, pScrn->yDpi,
pScrn->displayWidth);
break;
case 4:
ret = xf4bppScreenInit(pScreen, FbBase,
pScrn->virtualX, pScrn->virtualY,
pScrn->xDpi, pScrn->yDpi,
pScrn->displayWidth);
break;
case 8:
ret = cfbScreenInit(pScreen, FbBase,
pScrn->virtualX, pScrn->virtualY,
pScrn->xDpi, pScrn->yDpi,
pScrn->displayWidth);
break;
case 16:
ret = cfb16ScreenInit(pScreen, FbBase,
pScrn->virtualX, pScrn->virtualY,
pScrn->xDpi, pScrn->yDpi,
pScrn->displayWidth);
break;
case 24:
ret = cfb24ScreenInit(pScreen, FbBase,
pScrn->virtualX, pScrn->virtualY,
pScrn->xDpi, pScrn->yDpi,
pScrn->displayWidth);
break;
case 32:
ret = cfb32ScreenInit(pScreen, FbBase,
pScrn->virtualX, pScrn->virtualY,
pScrn->xDpi, pScrn->yDpi,
pScrn->displayWidth);
break;
default:
print a message about an internal error;
ret = FALSE;
break;
}
if (!ret)
return FALSE;
/* Override the default mask/offset settings */
if (pScrn->bitsPerPixel > 8) {
for (i = 0, visual = pScreen->visuals;
i < pScreen->numVisuals; i++, visual++) {
if ((visual->class | DynamicClass) == DirectColor) {
visual->offsetRed = pScrn->offset.red;
visual->offsetGreen = pScrn->offset.green;
visual->offsetBlue = pScrn->offset.blue;
visual->redMask = pScrn->mask.red;
visual->greenMask = pScrn->mask.green;
visual->blueMask = pScrn->mask.blue;
}
}
}
/*
* If banking is needed, initialise an miBankInfoRec (defined in
* "mibank.h"), and call miInitializeBanking().
*/
if (!miInitializeBanking(pScreen, pScrn->virtualX, pScrn->virtualY,
pScrn->displayWidth, pBankInfo))
return FALSE;
/*
* If backing store is to be supported (as is usually the case),
* initialise it.
*/
miInitializeBackingStore(pScreen);
/*
* Set initial black & white colourmap indices.
*/
xf86SetBlackWhitePixels(pScreen);
/*
* Install colourmap functions. If using the vgahw module,
* vgaHandleColormaps would usually be called here.
*/
...
/*
* Initialise cursor functions. This example is for the mi
* software cursor.
*/
miDCInitialize(pScreen, xf86GetPointerScreenFuncs());
/* Initialise the default colourmap */
switch (pScrn->depth) {
case 1:
if (!xf1bppCreateDefColormap(pScreen))
return FALSE;
break;
case 4:
if (!xf4bppCreateDefColormap(pScreen))
return FALSE;
break;
default:
if (!cfbCreateDefColormap(pScreen))
return FALSE;
break;
}
/*
* Wrap the CloseScreen vector and set SaveScreen.
*/
ZZZPTR(pScrn)->CloseScreen = pScreen->CloseScreen;
pScreen->CloseScreen = ZZZCloseScreen;
pScreen->SaveScreen = ZZZSaveScreen;
/* Report any unused options (only for the first generation) */
if (serverGeneration == 1) {
xf86ShowUnusedOptions(pScrn->scrnIndex, pScrn->options);
}
/* Done */
return TRUE;
}
20.3.11 SwitchMode
Define the SwitchMode() function if mode switching is supported by the
driver.
static Bool
ZZZSwitchMode(int scrnIndex, DisplayModePtr mode, int flags)
{
return ZZZModeInit(xf86Screens[scrnIndex], mode);
}
20.3.12 AdjustFrame
Define the AdjustFrame() function if the driver supports this.
static void
ZZZAdjustFrame(int scrnIndex, int x, int y, int flags)
{
/* Adjust the viewport */
}
20.3.13 EnterVT, LeaveVT
Define the EnterVT() and LeaveVT() functions.
These functions are mandatory.
static Bool
ZZZEnterVT(int scrnIndex, int flags)
{
ScrnInfoPtr pScrn = xf86Screens[scrnIndex];
return ZZZModeInit(pScrn, pScrn->currentMode);
}
static void
ZZZLeaveVT(int scrnIndex, int flags)
{
ScrnInfoPtr pScrn = xf86Screens[scrnIndex];
ZZZRestore(pScrn);
}
20.3.14 CloseScreen
Define the CloseScreen() function:
This function is mandatory. Note that it unwraps the previously wrapped
pScreen->CloseScreen, and finishes by calling it.
static Bool
ZZZCloseScreen(int scrnIndex, ScreenPtr pScreen)
{
ScrnInfoPtr pScrn = xf86Screens[scrnIndex];
if (pScrn->vtSema) {
ZZZRestore(pScrn);
ZZZUnmapMem(pScrn);
}
pScrn->vtSema = FALSE;
pScreen->CloseScreen = ZZZPTR(pScrn)->CloseScreen;
return (*pScreen->CloseScreen)(scrnIndex, pScreen);
}
20.3.15 SaveScreen
Define the SaveScreen() function (the screen blanking function). When using
the vgahw module, this will typically be:
static Bool
ZZZSaveScreen(ScreenPtr pScreen, int mode)
{
return vgaHWSaveScreen(pScreen, mode);
}
This function is mandatory. Before modifying any hardware register directly
this function needs to make sure that the Xserver is active by checking if
pScrn is non-NULL and for pScrn->vtSema == TRUE.
20.3.16 FreeScreen
Define the FreeScreen() function. This function is optional. It should be
defined if the ScrnInfoRec driverPrivate field is used so that it can be
freed when a screen is deleted by the common layer for reasons possibly
beyond the driver's control. This function is not used in during normal
(error free) operation. The per-generation data is freed by the Clos-
eScreen() function.
static void
ZZZFreeScreen(int scrnIndex, int flags)
{
/*
* If the vgahw module is used vgaHWFreeHWRec() would be called
* here.
*/
ZZZFreeRec(xf86Screens[scrnIndex]);
}
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