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Documentation: PCI: convert pci.txt to reST

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Convert plain text documentation to reStructuredText format and add it to
Sphinx TOC tree.  No essential content change.

Move the description of struct pci_driver and struct pci_device_id into
in-source comments.

Signed-off-by: Changbin Du <changbin.du@gmail.com>
[bhelgaas: fix kernel-doc warnings related to moving descriptions to
linux/pci.h, fix "space tab" whitespace errors in mod_devicetable.h]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
This commit is contained in:
Changbin Du 2019-05-14 22:47:24 +08:00 committed by Bjorn Helgaas
parent c42eaffa16
commit 229b4e0728
4 changed files with 221 additions and 212 deletions
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2
Documentation/PCI/index.rst
View File

@ -7,3 +7,5 @@ Linux PCI Bus Subsystem
.. toctree:: .. toctree::
:maxdepth: 2 :maxdepth: 2
:numbered: :numbered:
pci

354
Documentation/PCI/pci.txt → Documentation/PCI/pci.rst
View File

@ -1,10 +1,12 @@
.. SPDX-License-Identifier: GPL-2.0
How To Write Linux PCI Drivers ==============================
How To Write Linux PCI Drivers
==============================
by Martin Mares <mj@ucw.cz> on 07-Feb-2000 :Authors: - Martin Mares <mj@ucw.cz>
updated by Grant Grundler <grundler@parisc-linux.org> on 23-Dec-2006 - Grant Grundler <grundler@parisc-linux.org>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The world of PCI is vast and full of (mostly unpleasant) surprises. The world of PCI is vast and full of (mostly unpleasant) surprises.
Since each CPU architecture implements different chip-sets and PCI devices Since each CPU architecture implements different chip-sets and PCI devices
have different requirements (erm, "features"), the result is the PCI support have different requirements (erm, "features"), the result is the PCI support
@ -15,8 +17,7 @@ PCI device drivers.
A more complete resource is the third edition of "Linux Device Drivers" A more complete resource is the third edition of "Linux Device Drivers"
by Jonathan Corbet, Alessandro Rubini, and Greg Kroah-Hartman. by Jonathan Corbet, Alessandro Rubini, and Greg Kroah-Hartman.
LDD3 is available for free (under Creative Commons License) from: LDD3 is available for free (under Creative Commons License) from:
http://lwn.net/Kernel/LDD3/.
http://lwn.net/Kernel/LDD3/
However, keep in mind that all documents are subject to "bit rot". However, keep in mind that all documents are subject to "bit rot".
Refer to the source code if things are not working as described here. Refer to the source code if things are not working as described here.
@ -25,9 +26,8 @@ Please send questions/comments/patches about Linux PCI API to the
"Linux PCI" <linux-pci@atrey.karlin.mff.cuni.cz> mailing list. "Linux PCI" <linux-pci@atrey.karlin.mff.cuni.cz> mailing list.
Structure of PCI drivers
0. Structure of PCI drivers ========================
~~~~~~~~~~~~~~~~~~~~~~~~~~~
PCI drivers "discover" PCI devices in a system via pci_register_driver(). PCI drivers "discover" PCI devices in a system via pci_register_driver().
Actually, it's the other way around. When the PCI generic code discovers Actually, it's the other way around. When the PCI generic code discovers
a new device, the driver with a matching "description" will be notified. a new device, the driver with a matching "description" will be notified.
@ -42,24 +42,25 @@ pointers and thus dictates the high level structure of a driver.
Once the driver knows about a PCI device and takes ownership, the Once the driver knows about a PCI device and takes ownership, the
driver generally needs to perform the following initialization: driver generally needs to perform the following initialization:
Enable the device - Enable the device
Request MMIO/IOP resources - Request MMIO/IOP resources
Set the DMA mask size (for both coherent and streaming DMA) - Set the DMA mask size (for both coherent and streaming DMA)
Allocate and initialize shared control data (pci_allocate_coherent()) - Allocate and initialize shared control data (pci_allocate_coherent())
Access device configuration space (if needed) - Access device configuration space (if needed)
Register IRQ handler (request_irq()) - Register IRQ handler (request_irq())
Initialize non-PCI (i.e. LAN/SCSI/etc parts of the chip) - Initialize non-PCI (i.e. LAN/SCSI/etc parts of the chip)
Enable DMA/processing engines - Enable DMA/processing engines
When done using the device, and perhaps the module needs to be unloaded, When done using the device, and perhaps the module needs to be unloaded,
the driver needs to take the follow steps: the driver needs to take the follow steps:
Disable the device from generating IRQs
Release the IRQ (free_irq()) - Disable the device from generating IRQs
Stop all DMA activity - Release the IRQ (free_irq())
Release DMA buffers (both streaming and coherent) - Stop all DMA activity
Unregister from other subsystems (e.g. scsi or netdev) - Release DMA buffers (both streaming and coherent)
Release MMIO/IOP resources - Unregister from other subsystems (e.g. scsi or netdev)
Disable the device - Release MMIO/IOP resources
- Disable the device
Most of these topics are covered in the following sections. Most of these topics are covered in the following sections.
For the rest look at LDD3 or <linux/pci.h> . For the rest look at LDD3 or <linux/pci.h> .
@ -70,99 +71,38 @@ completely empty or just returning an appropriate error codes to avoid
lots of ifdefs in the drivers. lots of ifdefs in the drivers.
pci_register_driver() call
==========================
1. pci_register_driver() call PCI device drivers call ``pci_register_driver()`` during their
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PCI device drivers call pci_register_driver() during their
initialization with a pointer to a structure describing the driver initialization with a pointer to a structure describing the driver
(struct pci_driver): (``struct pci_driver``):
field name Description .. kernel-doc:: include/linux/pci.h
---------- ------------------------------------------------------ :functions: pci_driver
id_table Pointer to table of device ID's the driver is
interested in. Most drivers should export this
table using MODULE_DEVICE_TABLE(pci,...).
probe This probing function gets called (during execution The ID table is an array of ``struct pci_device_id`` entries ending with an
of pci_register_driver() for already existing
devices or later if a new device gets inserted) for
all PCI devices which match the ID table and are not
"owned" by the other drivers yet. This function gets
passed a "struct pci_dev *" for each device whose
entry in the ID table matches the device. The probe
function returns zero when the driver chooses to
take "ownership" of the device or an error code
(negative number) otherwise.
The probe function always gets called from process
context, so it can sleep.
remove The remove() function gets called whenever a device
being handled by this driver is removed (either during
deregistration of the driver or when it's manually
pulled out of a hot-pluggable slot).
The remove function always gets called from process
context, so it can sleep.
suspend Put device into low power state.
suspend_late Put device into low power state.
resume_early Wake device from low power state.
resume Wake device from low power state.
(Please see Documentation/power/pci.txt for descriptions
of PCI Power Management and the related functions.)
shutdown Hook into reboot_notifier_list (kernel/sys.c).
Intended to stop any idling DMA operations.
Useful for enabling wake-on-lan (NIC) or changing
the power state of a device before reboot.
e.g. drivers/net/e100.c.
err_handler See Documentation/PCI/pci-error-recovery.txt
The ID table is an array of struct pci_device_id entries ending with an
all-zero entry. Definitions with static const are generally preferred. all-zero entry. Definitions with static const are generally preferred.
Each entry consists of: .. kernel-doc:: include/linux/mod_devicetable.h
:functions: pci_device_id
vendor,device Vendor and device ID to match (or PCI_ANY_ID) Most drivers only need ``PCI_DEVICE()`` or ``PCI_DEVICE_CLASS()`` to set up
subvendor, Subsystem vendor and device ID to match (or PCI_ANY_ID)
subdevice,
class Device class, subclass, and "interface" to match.
See Appendix D of the PCI Local Bus Spec or
include/linux/pci_ids.h for a full list of classes.
Most drivers do not need to specify class/class_mask
as vendor/device is normally sufficient.
class_mask limit which sub-fields of the class field are compared.
See drivers/scsi/sym53c8xx_2/ for example of usage.
driver_data Data private to the driver.
Most drivers don't need to use driver_data field.
Best practice is to use driver_data as an index
into a static list of equivalent device types,
instead of using it as a pointer.
Most drivers only need PCI_DEVICE() or PCI_DEVICE_CLASS() to set up
a pci_device_id table. a pci_device_id table.
New PCI IDs may be added to a device driver pci_ids table at runtime New PCI IDs may be added to a device driver pci_ids table at runtime
as shown below: as shown below::
echo "vendor device subvendor subdevice class class_mask driver_data" > \ echo "vendor device subvendor subdevice class class_mask driver_data" > \
/sys/bus/pci/drivers/{driver}/new_id /sys/bus/pci/drivers/{driver}/new_id
All fields are passed in as hexadecimal values (no leading 0x). All fields are passed in as hexadecimal values (no leading 0x).
The vendor and device fields are mandatory, the others are optional. Users The vendor and device fields are mandatory, the others are optional. Users
need pass only as many optional fields as necessary: need pass only as many optional fields as necessary:
o subvendor and subdevice fields default to PCI_ANY_ID (FFFFFFFF)
o class and classmask fields default to 0 - subvendor and subdevice fields default to PCI_ANY_ID (FFFFFFFF)
o driver_data defaults to 0UL. - class and classmask fields default to 0
- driver_data defaults to 0UL.
Note that driver_data must match the value used by any of the pci_device_id Note that driver_data must match the value used by any of the pci_device_id
entries defined in the driver. This makes the driver_data field mandatory entries defined in the driver. This makes the driver_data field mandatory
@ -175,29 +115,31 @@ When the driver exits, it just calls pci_unregister_driver() and the PCI layer
automatically calls the remove hook for all devices handled by the driver. automatically calls the remove hook for all devices handled by the driver.
1.1 "Attributes" for driver functions/data "Attributes" for driver functions/data
--------------------------------------
Please mark the initialization and cleanup functions where appropriate Please mark the initialization and cleanup functions where appropriate
(the corresponding macros are defined in <linux/init.h>): (the corresponding macros are defined in <linux/init.h>):
====== =================================================
__init Initialization code. Thrown away after the driver __init Initialization code. Thrown away after the driver
initializes. initializes.
__exit Exit code. Ignored for non-modular drivers. __exit Exit code. Ignored for non-modular drivers.
====== =================================================
Tips on when/where to use the above attributes: Tips on when/where to use the above attributes:
o The module_init()/module_exit() functions (and all - The module_init()/module_exit() functions (and all
initialization functions called _only_ from these) initialization functions called _only_ from these)
should be marked __init/__exit. should be marked __init/__exit.
o Do not mark the struct pci_driver. - Do not mark the struct pci_driver.
o Do NOT mark a function if you are not sure which mark to use. - Do NOT mark a function if you are not sure which mark to use.
Better to not mark the function than mark the function wrong. Better to not mark the function than mark the function wrong.
How to find PCI devices manually
2. How to find PCI devices manually ================================
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PCI drivers should have a really good reason for not using the PCI drivers should have a really good reason for not using the
pci_register_driver() interface to search for PCI devices. pci_register_driver() interface to search for PCI devices.
@ -207,17 +149,17 @@ E.g. combined serial/parallel port/floppy controller.
A manual search may be performed using the following constructs: A manual search may be performed using the following constructs:
Searching by vendor and device ID: Searching by vendor and device ID::
struct pci_dev *dev = NULL; struct pci_dev *dev = NULL;
while (dev = pci_get_device(VENDOR_ID, DEVICE_ID, dev)) while (dev = pci_get_device(VENDOR_ID, DEVICE_ID, dev))
configure_device(dev); configure_device(dev);
Searching by class ID (iterate in a similar way): Searching by class ID (iterate in a similar way)::
pci_get_class(CLASS_ID, dev) pci_get_class(CLASS_ID, dev)
Searching by both vendor/device and subsystem vendor/device ID: Searching by both vendor/device and subsystem vendor/device ID::
pci_get_subsys(VENDOR_ID,DEVICE_ID, SUBSYS_VENDOR_ID, SUBSYS_DEVICE_ID, dev). pci_get_subsys(VENDOR_ID,DEVICE_ID, SUBSYS_VENDOR_ID, SUBSYS_DEVICE_ID, dev).
@ -230,21 +172,20 @@ the pci_dev that they return. You must eventually (possibly at module unload)
decrement the reference count on these devices by calling pci_dev_put(). decrement the reference count on these devices by calling pci_dev_put().
Device Initialization Steps
3. Device Initialization Steps ===========================
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
As noted in the introduction, most PCI drivers need the following steps As noted in the introduction, most PCI drivers need the following steps
for device initialization: for device initialization:
Enable the device - Enable the device
Request MMIO/IOP resources - Request MMIO/IOP resources
Set the DMA mask size (for both coherent and streaming DMA) - Set the DMA mask size (for both coherent and streaming DMA)
Allocate and initialize shared control data (pci_allocate_coherent()) - Allocate and initialize shared control data (pci_allocate_coherent())
Access device configuration space (if needed) - Access device configuration space (if needed)
Register IRQ handler (request_irq()) - Register IRQ handler (request_irq())
Initialize non-PCI (i.e. LAN/SCSI/etc parts of the chip) - Initialize non-PCI (i.e. LAN/SCSI/etc parts of the chip)
Enable DMA/processing engines. - Enable DMA/processing engines.
The driver can access PCI config space registers at any time. The driver can access PCI config space registers at any time.
(Well, almost. When running BIST, config space can go away...but (Well, almost. When running BIST, config space can go away...but
@ -252,26 +193,29 @@ that will just result in a PCI Bus Master Abort and config reads
will return garbage). will return garbage).
3.1 Enable the PCI device Enable the PCI device
~~~~~~~~~~~~~~~~~~~~~~~~~ ---------------------
Before touching any device registers, the driver needs to enable Before touching any device registers, the driver needs to enable
the PCI device by calling pci_enable_device(). This will: the PCI device by calling pci_enable_device(). This will:
o wake up the device if it was in suspended state,
o allocate I/O and memory regions of the device (if BIOS did not),
o allocate an IRQ (if BIOS did not).
NOTE: pci_enable_device() can fail! Check the return value. - wake up the device if it was in suspended state,
- allocate I/O and memory regions of the device (if BIOS did not),
- allocate an IRQ (if BIOS did not).
[ OS BUG: we don't check resource allocations before enabling those .. note::
resources. The sequence would make more sense if we called pci_enable_device() can fail! Check the return value.
pci_request_resources() before calling pci_enable_device().
Currently, the device drivers can't detect the bug when when two .. warning::
devices have been allocated the same range. This is not a common OS BUG: we don't check resource allocations before enabling those
problem and unlikely to get fixed soon. resources. The sequence would make more sense if we called
pci_request_resources() before calling pci_enable_device().
Currently, the device drivers can't detect the bug when when two
devices have been allocated the same range. This is not a common
problem and unlikely to get fixed soon.
This has been discussed before but not changed as of 2.6.19:
http://lkml.org/lkml/2006/3/2/194
This has been discussed before but not changed as of 2.6.19:
http://lkml.org/lkml/2006/3/2/194
]
pci_set_master() will enable DMA by setting the bus master bit pci_set_master() will enable DMA by setting the bus master bit
in the PCI_COMMAND register. It also fixes the latency timer value if in the PCI_COMMAND register. It also fixes the latency timer value if
@ -288,8 +232,8 @@ pci_try_set_mwi() to have the system do its best effort at enabling
Mem-Wr-Inval. Mem-Wr-Inval.
3.2 Request MMIO/IOP resources Request MMIO/IOP resources
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ --------------------------
Memory (MMIO), and I/O port addresses should NOT be read directly Memory (MMIO), and I/O port addresses should NOT be read directly
from the PCI device config space. Use the values in the pci_dev structure from the PCI device config space. Use the values in the pci_dev structure
as the PCI "bus address" might have been remapped to a "host physical" as the PCI "bus address" might have been remapped to a "host physical"
@ -304,9 +248,10 @@ Conversely, drivers should call pci_release_region() AFTER
calling pci_disable_device(). calling pci_disable_device().
The idea is to prevent two devices colliding on the same address range. The idea is to prevent two devices colliding on the same address range.
[ See OS BUG comment above. Currently (2.6.19), The driver can only .. tip::
determine MMIO and IO Port resource availability _after_ calling See OS BUG comment above. Currently (2.6.19), The driver can only
pci_enable_device(). ] determine MMIO and IO Port resource availability _after_ calling
pci_enable_device().
Generic flavors of pci_request_region() are request_mem_region() Generic flavors of pci_request_region() are request_mem_region()
(for MMIO ranges) and request_region() (for IO Port ranges). (for MMIO ranges) and request_region() (for IO Port ranges).
@ -316,12 +261,13 @@ BARs.
Also see pci_request_selected_regions() below. Also see pci_request_selected_regions() below.
3.3 Set the DMA mask size Set the DMA mask size
~~~~~~~~~~~~~~~~~~~~~~~~~ ---------------------
[ If anything below doesn't make sense, please refer to .. note::
Documentation/DMA-API.txt. This section is just a reminder that If anything below doesn't make sense, please refer to
drivers need to indicate DMA capabilities of the device and is not Documentation/DMA-API.txt. This section is just a reminder that
an authoritative source for DMA interfaces. ] drivers need to indicate DMA capabilities of the device and is not
an authoritative source for DMA interfaces.
While all drivers should explicitly indicate the DMA capability While all drivers should explicitly indicate the DMA capability
(e.g. 32 or 64 bit) of the PCI bus master, devices with more than (e.g. 32 or 64 bit) of the PCI bus master, devices with more than
@ -342,23 +288,23 @@ Many 64-bit "PCI" devices (before PCI-X) and some PCI-X devices are
("consistent") data. ("consistent") data.
3.4 Setup shared control data Setup shared control data
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -------------------------
Once the DMA masks are set, the driver can allocate "consistent" (a.k.a. shared) Once the DMA masks are set, the driver can allocate "consistent" (a.k.a. shared)
memory. See Documentation/DMA-API.txt for a full description of memory. See Documentation/DMA-API.txt for a full description of
the DMA APIs. This section is just a reminder that it needs to be done the DMA APIs. This section is just a reminder that it needs to be done
before enabling DMA on the device. before enabling DMA on the device.
3.5 Initialize device registers Initialize device registers
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ---------------------------
Some drivers will need specific "capability" fields programmed Some drivers will need specific "capability" fields programmed
or other "vendor specific" register initialized or reset. or other "vendor specific" register initialized or reset.
E.g. clearing pending interrupts. E.g. clearing pending interrupts.
3.6 Register IRQ handler Register IRQ handler
~~~~~~~~~~~~~~~~~~~~~~~~ --------------------
While calling request_irq() is the last step described here, While calling request_irq() is the last step described here,
this is often just another intermediate step to initialize a device. this is often just another intermediate step to initialize a device.
This step can often be deferred until the device is opened for use. This step can often be deferred until the device is opened for use.
@ -396,6 +342,7 @@ and msix_enabled flags in the pci_dev structure after calling
pci_alloc_irq_vectors. pci_alloc_irq_vectors.
There are (at least) two really good reasons for using MSI: There are (at least) two really good reasons for using MSI:
1) MSI is an exclusive interrupt vector by definition. 1) MSI is an exclusive interrupt vector by definition.
This means the interrupt handler doesn't have to verify This means the interrupt handler doesn't have to verify
its device caused the interrupt. its device caused the interrupt.
@ -410,24 +357,23 @@ See drivers/infiniband/hw/mthca/ or drivers/net/tg3.c for examples
of MSI/MSI-X usage. of MSI/MSI-X usage.
PCI device shutdown
4. PCI device shutdown ===================
~~~~~~~~~~~~~~~~~~~~~~~
When a PCI device driver is being unloaded, most of the following When a PCI device driver is being unloaded, most of the following
steps need to be performed: steps need to be performed:
Disable the device from generating IRQs - Disable the device from generating IRQs
Release the IRQ (free_irq()) - Release the IRQ (free_irq())
Stop all DMA activity - Stop all DMA activity
Release DMA buffers (both streaming and consistent) - Release DMA buffers (both streaming and consistent)
Unregister from other subsystems (e.g. scsi or netdev) - Unregister from other subsystems (e.g. scsi or netdev)
Disable device from responding to MMIO/IO Port addresses - Disable device from responding to MMIO/IO Port addresses
Release MMIO/IO Port resource(s) - Release MMIO/IO Port resource(s)
4.1 Stop IRQs on the device Stop IRQs on the device
~~~~~~~~~~~~~~~~~~~~~~~~~~~ -----------------------
How to do this is chip/device specific. If it's not done, it opens How to do this is chip/device specific. If it's not done, it opens
the possibility of a "screaming interrupt" if (and only if) the possibility of a "screaming interrupt" if (and only if)
the IRQ is shared with another device. the IRQ is shared with another device.
@ -446,16 +392,16 @@ MSI and MSI-X are defined to be exclusive interrupts and thus
are not susceptible to the "screaming interrupt" problem. are not susceptible to the "screaming interrupt" problem.
4.2 Release the IRQ Release the IRQ
~~~~~~~~~~~~~~~~~~~ ---------------
Once the device is quiesced (no more IRQs), one can call free_irq(). Once the device is quiesced (no more IRQs), one can call free_irq().
This function will return control once any pending IRQs are handled, This function will return control once any pending IRQs are handled,
"unhook" the drivers IRQ handler from that IRQ, and finally release "unhook" the drivers IRQ handler from that IRQ, and finally release
the IRQ if no one else is using it. the IRQ if no one else is using it.
4.3 Stop all DMA activity Stop all DMA activity
~~~~~~~~~~~~~~~~~~~~~~~~~ ---------------------
It's extremely important to stop all DMA operations BEFORE attempting It's extremely important to stop all DMA operations BEFORE attempting
to deallocate DMA control data. Failure to do so can result in memory to deallocate DMA control data. Failure to do so can result in memory
corruption, hangs, and on some chip-sets a hard crash. corruption, hangs, and on some chip-sets a hard crash.
@ -467,8 +413,8 @@ While this step sounds obvious and trivial, several "mature" drivers
didn't get this step right in the past. didn't get this step right in the past.
4.4 Release DMA buffers Release DMA buffers
~~~~~~~~~~~~~~~~~~~~~~~ -------------------
Once DMA is stopped, clean up streaming DMA first. Once DMA is stopped, clean up streaming DMA first.
I.e. unmap data buffers and return buffers to "upstream" I.e. unmap data buffers and return buffers to "upstream"
owners if there is one. owners if there is one.
@ -478,8 +424,8 @@ Then clean up "consistent" buffers which contain the control data.
See Documentation/DMA-API.txt for details on unmapping interfaces. See Documentation/DMA-API.txt for details on unmapping interfaces.
4.5 Unregister from other subsystems Unregister from other subsystems
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ --------------------------------
Most low level PCI device drivers support some other subsystem Most low level PCI device drivers support some other subsystem
like USB, ALSA, SCSI, NetDev, Infiniband, etc. Make sure your like USB, ALSA, SCSI, NetDev, Infiniband, etc. Make sure your
driver isn't losing resources from that other subsystem. driver isn't losing resources from that other subsystem.
@ -487,31 +433,30 @@ If this happens, typically the symptom is an Oops (panic) when
the subsystem attempts to call into a driver that has been unloaded. the subsystem attempts to call into a driver that has been unloaded.
4.6 Disable Device from responding to MMIO/IO Port addresses Disable Device from responding to MMIO/IO Port addresses
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ --------------------------------------------------------
io_unmap() MMIO or IO Port resources and then call pci_disable_device(). io_unmap() MMIO or IO Port resources and then call pci_disable_device().
This is the symmetric opposite of pci_enable_device(). This is the symmetric opposite of pci_enable_device().
Do not access device registers after calling pci_disable_device(). Do not access device registers after calling pci_disable_device().
4.7 Release MMIO/IO Port Resource(s) Release MMIO/IO Port Resource(s)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ --------------------------------
Call pci_release_region() to mark the MMIO or IO Port range as available. Call pci_release_region() to mark the MMIO or IO Port range as available.
Failure to do so usually results in the inability to reload the driver. Failure to do so usually results in the inability to reload the driver.
How to access PCI config space
==============================
5. How to access PCI config space You can use `pci_(read|write)_config_(byte|word|dword)` to access the config
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ space of a device represented by `struct pci_dev *`. All these functions return
0 when successful or an error code (`PCIBIOS_...`) which can be translated to a
You can use pci_(read|write)_config_(byte|word|dword) to access the config text string by pcibios_strerror. Most drivers expect that accesses to valid PCI
space of a device represented by struct pci_dev *. All these functions return 0
when successful or an error code (PCIBIOS_...) which can be translated to a text
string by pcibios_strerror. Most drivers expect that accesses to valid PCI
devices don't fail. devices don't fail.
If you don't have a struct pci_dev available, you can call If you don't have a struct pci_dev available, you can call
pci_bus_(read|write)_config_(byte|word|dword) to access a given device `pci_bus_(read|write)_config_(byte|word|dword)` to access a given device
and function on that bus. and function on that bus.
If you access fields in the standard portion of the config header, please If you access fields in the standard portion of the config header, please
@ -522,10 +467,10 @@ pci_find_capability() for the particular capability and it will find the
corresponding register block for you. corresponding register block for you.
Other interesting functions
===========================
6. Other interesting functions ============================= ================================================
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
pci_get_domain_bus_and_slot() Find pci_dev corresponding to given domain, pci_get_domain_bus_and_slot() Find pci_dev corresponding to given domain,
bus and slot and number. If the device is bus and slot and number. If the device is
found, its reference count is increased. found, its reference count is increased.
@ -539,11 +484,11 @@ pci_set_drvdata() Set private driver data pointer for a pci_dev
pci_get_drvdata() Return private driver data pointer for a pci_dev pci_get_drvdata() Return private driver data pointer for a pci_dev
pci_set_mwi() Enable Memory-Write-Invalidate transactions. pci_set_mwi() Enable Memory-Write-Invalidate transactions.
pci_clear_mwi() Disable Memory-Write-Invalidate transactions. pci_clear_mwi() Disable Memory-Write-Invalidate transactions.
============================= ================================================
Miscellaneous hints
7. Miscellaneous hints ===================
~~~~~~~~~~~~~~~~~~~~~~
When displaying PCI device names to the user (for example when a driver wants When displaying PCI device names to the user (for example when a driver wants
to tell the user what card has it found), please use pci_name(pci_dev). to tell the user what card has it found), please use pci_name(pci_dev).
@ -559,9 +504,8 @@ on the bus need to be capable of doing it, so this is something which needs
to be handled by platform and generic code, not individual drivers. to be handled by platform and generic code, not individual drivers.
Vendor and device identifications
8. Vendor and device identifications =================================
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Do not add new device or vendor IDs to include/linux/pci_ids.h unless they Do not add new device or vendor IDs to include/linux/pci_ids.h unless they
are shared across multiple drivers. You can add private definitions in are shared across multiple drivers. You can add private definitions in
@ -575,28 +519,27 @@ There are mirrors of the pci.ids file at http://pciids.sourceforge.net/
and https://github.com/pciutils/pciids. and https://github.com/pciutils/pciids.
Obsolete functions
9. Obsolete functions ==================
~~~~~~~~~~~~~~~~~~~~~
There are several functions which you might come across when trying to There are several functions which you might come across when trying to
port an old driver to the new PCI interface. They are no longer present port an old driver to the new PCI interface. They are no longer present
in the kernel as they aren't compatible with hotplug or PCI domains or in the kernel as they aren't compatible with hotplug or PCI domains or
having sane locking. having sane locking.
================= ===========================================
pci_find_device() Superseded by pci_get_device() pci_find_device() Superseded by pci_get_device()
pci_find_subsys() Superseded by pci_get_subsys() pci_find_subsys() Superseded by pci_get_subsys()
pci_find_slot() Superseded by pci_get_domain_bus_and_slot() pci_find_slot() Superseded by pci_get_domain_bus_and_slot()
pci_get_slot() Superseded by pci_get_domain_bus_and_slot() pci_get_slot() Superseded by pci_get_domain_bus_and_slot()
================= ===========================================
The alternative is the traditional PCI device driver that walks PCI The alternative is the traditional PCI device driver that walks PCI
device lists. This is still possible but discouraged. device lists. This is still possible but discouraged.
MMIO Space and "Write Posting"
10. MMIO Space and "Write Posting" ==============================
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Converting a driver from using I/O Port space to using MMIO space Converting a driver from using I/O Port space to using MMIO space
often requires some additional changes. Specifically, "write posting" often requires some additional changes. Specifically, "write posting"
@ -609,14 +552,14 @@ the CPU before the transaction has reached its destination.
Thus, timing sensitive code should add readl() where the CPU is Thus, timing sensitive code should add readl() where the CPU is
expected to wait before doing other work. The classic "bit banging" expected to wait before doing other work. The classic "bit banging"
sequence works fine for I/O Port space: sequence works fine for I/O Port space::
for (i = 8; --i; val >>= 1) { for (i = 8; --i; val >>= 1) {
outb(val & 1, ioport_reg); /* write bit */ outb(val & 1, ioport_reg); /* write bit */
udelay(10); udelay(10);
} }
The same sequence for MMIO space should be: The same sequence for MMIO space should be::
for (i = 8; --i; val >>= 1) { for (i = 8; --i; val >>= 1) {
writeb(val & 1, mmio_reg); /* write bit */ writeb(val & 1, mmio_reg); /* write bit */
@ -633,4 +576,3 @@ handle the PCI master abort on all platforms if the PCI device is
expected to not respond to a readl(). Most x86 platforms will allow expected to not respond to a readl(). Most x86 platforms will allow
MMIO reads to master abort (a.k.a. "Soft Fail") and return garbage MMIO reads to master abort (a.k.a. "Soft Fail") and return garbage
(e.g. ~0). But many RISC platforms will crash (a.k.a."Hard Fail"). (e.g. ~0). But many RISC platforms will crash (a.k.a."Hard Fail").

29
include/linux/mod_devicetable.h
View File

@ -16,6 +16,25 @@ typedef unsigned long kernel_ulong_t;
#define PCI_ANY_ID (~0) #define PCI_ANY_ID (~0)
/**
* struct pci_device_id - PCI device ID structure
* @vendor: Vendor ID to match (or PCI_ANY_ID)
* @device: Device ID to match (or PCI_ANY_ID)
* @subvendor: Subsystem vendor ID to match (or PCI_ANY_ID)
* @subdevice: Subsystem device ID to match (or PCI_ANY_ID)
* @class: Device class, subclass, and "interface" to match.
* See Appendix D of the PCI Local Bus Spec or
* include/linux/pci_ids.h for a full list of classes.
* Most drivers do not need to specify class/class_mask
* as vendor/device is normally sufficient.
* @class_mask: Limit which sub-fields of the class field are compared.
* See drivers/scsi/sym53c8xx_2/ for example of usage.
* @driver_data: Data private to the driver.
* Most drivers don't need to use driver_data field.
* Best practice is to use driver_data as an index
* into a static list of equivalent device types,
* instead of using it as a pointer.
*/
struct pci_device_id { struct pci_device_id {
__u32 vendor, device; /* Vendor and device ID or PCI_ANY_ID*/ __u32 vendor, device; /* Vendor and device ID or PCI_ANY_ID*/
__u32 subvendor, subdevice; /* Subsystem ID's or PCI_ANY_ID */ __u32 subvendor, subdevice; /* Subsystem ID's or PCI_ANY_ID */
@ -257,17 +276,17 @@ struct pcmcia_device_id {
__u16 match_flags; __u16 match_flags;
__u16 manf_id; __u16 manf_id;
__u16 card_id; __u16 card_id;
__u8 func_id; __u8 func_id;
/* for real multi-function devices */ /* for real multi-function devices */
__u8 function; __u8 function;
/* for pseudo multi-function devices */ /* for pseudo multi-function devices */
__u8 device_no; __u8 device_no;
__u32 prod_id_hash[4]; __u32 prod_id_hash[4];
/* not matched against in kernelspace */ /* not matched against in kernelspace */
const char * prod_id[4]; const char * prod_id[4];

48
include/linux/pci.h
View File

@ -151,6 +151,8 @@ static inline const char *pci_power_name(pci_power_t state)
#define PCI_PM_BUS_WAIT 50 #define PCI_PM_BUS_WAIT 50
/** /**
* typedef pci_channel_state_t
*
* The pci_channel state describes connectivity between the CPU and * The pci_channel state describes connectivity between the CPU and
* the PCI device. If some PCI bus between here and the PCI device * the PCI device. If some PCI bus between here and the PCI device
* has crashed or locked up, this info is reflected here. * has crashed or locked up, this info is reflected here.
@ -775,6 +777,50 @@ struct pci_error_handlers {
struct module; struct module;
/**
* struct pci_driver - PCI driver structure
* @node: List of driver structures.
* @name: Driver name.
* @id_table: Pointer to table of device IDs the driver is
* interested in. Most drivers should export this
* table using MODULE_DEVICE_TABLE(pci,...).
* @probe: This probing function gets called (during execution
* of pci_register_driver() for already existing
* devices or later if a new device gets inserted) for
* all PCI devices which match the ID table and are not
* "owned" by the other drivers yet. This function gets
* passed a "struct pci_dev \*" for each device whose
* entry in the ID table matches the device. The probe
* function returns zero when the driver chooses to
* take "ownership" of the device or an error code
* (negative number) otherwise.
* The probe function always gets called from process
* context, so it can sleep.
* @remove: The remove() function gets called whenever a device
* being handled by this driver is removed (either during
* deregistration of the driver or when it's manually
* pulled out of a hot-pluggable slot).
* The remove function always gets called from process
* context, so it can sleep.
* @suspend: Put device into low power state.
* @suspend_late: Put device into low power state.
* @resume_early: Wake device from low power state.
* @resume: Wake device from low power state.
* (Please see Documentation/power/pci.txt for descriptions
* of PCI Power Management and the related functions.)
* @shutdown: Hook into reboot_notifier_list (kernel/sys.c).
* Intended to stop any idling DMA operations.
* Useful for enabling wake-on-lan (NIC) or changing
* the power state of a device before reboot.
* e.g. drivers/net/e100.c.
* @sriov_configure: Optional driver callback to allow configuration of
* number of VFs to enable via sysfs "sriov_numvfs" file.
* @err_handler: See Documentation/PCI/pci-error-recovery.rst
* @groups: Sysfs attribute groups.
* @driver: Driver model structure.
* @dynids: List of dynamically added device IDs.
*/
struct pci_driver { struct pci_driver {
struct list_head node; struct list_head node;
const char *name; const char *name;
@ -2206,7 +2252,7 @@ static inline u8 pci_vpd_srdt_tag(const u8 *srdt)
/** /**
* pci_vpd_info_field_size - Extracts the information field length * pci_vpd_info_field_size - Extracts the information field length
* @lrdt: Pointer to the beginning of an information field header * @info_field: Pointer to the beginning of an information field header
* *
* Returns the extracted information field length. * Returns the extracted information field length.
*/ */