Documentation/process/submitting-drivers.rst - linux - Git at Google

 .. _submittingdrivers:

 Submitting Drivers For The Linux Kernel
 =======================================

 This document is intended to explain how to submit device drivers to the
 various kernel trees. Note that if you are interested in video card drivers
 you should probably talk to XFree86 (https://www.xfree86.org/) and/or X.Org
 (https://x.org/) instead.

 .. note::

    This document is old and has seen little maintenance in recent years; it
    should probably be updated or, perhaps better, just deleted.  Most of
    what is here can be found in the other development documents anyway.

    Oh, and we don't really recommend submitting changes to XFree86 :)

 Also read the :ref:`Documentation/process/submitting-patches.rst <submittingpatches>`
 document.


 Allocating Device Numbers
 -------------------------

 Major and minor numbers for block and character devices are allocated
 by the Linux assigned name and number authority (currently this is
 Torben Mathiasen). The site is https://www.lanana.org/. This
 also deals with allocating numbers for devices that are not going to
 be submitted to the mainstream kernel.
 See :ref:`Documentation/admin-guide/devices.rst <admin_devices>`
 for more information on this.

 If you don't use assigned numbers then when your device is submitted it will
 be given an assigned number even if that is different from values you may
 have shipped to customers before.

 Who To Submit Drivers To
 ------------------------

 Linux 2.0:
 	No new drivers are accepted for this kernel tree.

 Linux 2.2:
 	No new drivers are accepted for this kernel tree.

 Linux 2.4:
 	If the code area has a general maintainer then please submit it to
 	the maintainer listed in MAINTAINERS in the kernel file. If the
 	maintainer does not respond or you cannot find the appropriate
 	maintainer then please contact Willy Tarreau <w@1wt.eu>.

 Linux 2.6 and upper:
 	The same rules apply as 2.4 except that you should follow linux-kernel
 	to track changes in API's. The final contact point for Linux 2.6+
 	submissions is Andrew Morton.

 What Criteria Determine Acceptance
 ----------------------------------

 Licensing:
 		The code must be released to us under the
 		GNU General Public License. If you wish the driver to be
 		useful to other communities such as BSD you may release
 		under multiple licenses. If you choose to release under
 		licenses other than the GPL, you should include your
 		rationale for your license choices in your cover letter.
 		See accepted licenses at include/linux/module.h

 Copyright:
 		The copyright owner must agree to use of GPL.
 		It's best if the submitter and copyright owner
 		are the same person/entity. If not, the name of
 		the person/entity authorizing use of GPL should be
 		listed in case it's necessary to verify the will of
 		the copyright owner.

 Interfaces:
 		If your driver uses existing interfaces and behaves like
 		other drivers in the same class it will be much more likely
 		to be accepted than if it invents gratuitous new ones.
 		If you need to implement a common API over Linux and NT
 		drivers do it in userspace.

 Code:
 		Please use the Linux style of code formatting as documented
 		in :ref:`Documentation/process/coding-style.rst <codingStyle>`.
 		If you have sections of code
 		that need to be in other formats, for example because they
 		are shared with a windows driver kit and you want to
 		maintain them just once separate them out nicely and note
 		this fact.

 Portability:
 		Pointers are not always 32bits, not all computers are little
 		endian, people do not all have floating point and you
 		shouldn't use inline x86 assembler in your driver without
 		careful thought. Pure x86 drivers generally are not popular.
 		If you only have x86 hardware it is hard to test portability
 		but it is easy to make sure the code can easily be made
 		portable.

 Clarity:
 		It helps if anyone can see how to fix the driver. It helps
 		you because you get patches not bug reports. If you submit a
 		driver that intentionally obfuscates how the hardware works
 		it will go in the bitbucket.

 PM support:
 		Since Linux is used on many portable and desktop systems, your
 		driver is likely to be used on such a system and therefore it
 		should support basic power management by implementing, if
 		necessary, the .suspend and .resume methods used during the
 		system-wide suspend and resume transitions.  You should verify
 		that your driver correctly handles the suspend and resume, but
 		if you are unable to ensure that, please at least define the
 		.suspend method returning the -ENOSYS ("Function not
 		implemented") error.  You should also try to make sure that your
 		driver uses as little power as possible when it's not doing
 		anything.  For the driver testing instructions see
 		Documentation/power/drivers-testing.rst and for a relatively
 		complete overview of the power management issues related to
 		drivers see :ref:`Documentation/driver-api/pm/devices.rst <driverapi_pm_devices>`.

 Control:
 		In general if there is active maintenance of a driver by
 		the author then patches will be redirected to them unless
 		they are totally obvious and without need of checking.
 		If you want to be the contact and update point for the
 		driver it is a good idea to state this in the comments,
 		and include an entry in MAINTAINERS for your driver.

 What Criteria Do Not Determine Acceptance
 -----------------------------------------

 Vendor:
 		Being the hardware vendor and maintaining the driver is
 		often a good thing. If there is a stable working driver from
 		other people already in the tree don't expect 'we are the
 		vendor' to get your driver chosen. Ideally work with the
 		existing driver author to build a single perfect driver.

 Author:
 		It doesn't matter if a large Linux company wrote the driver,
 		or you did. Nobody has any special access to the kernel
 		tree. Anyone who tells you otherwise isn't telling the
 		whole story.


 Resources
 ---------

 Linux kernel master tree:
 	ftp.\ *country_code*\ .kernel.org:/pub/linux/kernel/...

 	where *country_code* == your country code, such as
 	**us**, **uk**, **fr**, etc.

 	https://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git

 Linux kernel mailing list:
 	linux-kernel@vger.kernel.org
 	[mail majordomo@vger.kernel.org to subscribe]

 Linux Device Drivers, Third Edition (covers 2.6.10):
 	https://lwn.net/Kernel/LDD3/  (free version)

 LWN.net:
 	Weekly summary of kernel development activity - https://lwn.net/

 	2.6 API changes:

 		https://lwn.net/Articles/2.6-kernel-api/

 	Porting drivers from prior kernels to 2.6:

 		https://lwn.net/Articles/driver-porting/

 KernelNewbies:
 	Documentation and assistance for new kernel programmers

 		https://kernelnewbies.org/

 Linux USB project:
 	http://www.linux-usb.org/

 How to NOT write kernel driver by Arjan van de Ven:
 	https://landley.net/kdocs/ols/2002/ols2002-pages-545-555.pdf

 Kernel Janitor:
 	https://kernelnewbies.org/KernelJanitors

 GIT, Fast Version Control System:
 	https://git-scm.com/
	.. _submittingdrivers:

	Submitting Drivers For The Linux Kernel
	=======================================

	This document is intended to explain how to submit device drivers to the
	various kernel trees. Note that if you are interested in video card drivers
	you should probably talk to XFree86 (https://www.xfree86.org/) and/or X.Org
	(https://x.org/) instead.

	.. note::

	This document is old and has seen little maintenance in recent years; it
	should probably be updated or, perhaps better, just deleted. Most of
	what is here can be found in the other development documents anyway.

	Oh, and we don't really recommend submitting changes to XFree86 :)

	Also read the :ref:`Documentation/process/submitting-patches.rst <submittingpatches>`
	document.


	Allocating Device Numbers
	-------------------------

	Major and minor numbers for block and character devices are allocated
	by the Linux assigned name and number authority (currently this is
	Torben Mathiasen). The site is https://www.lanana.org/. This
	also deals with allocating numbers for devices that are not going to
	be submitted to the mainstream kernel.
	See :ref:`Documentation/admin-guide/devices.rst <admin_devices>`
	for more information on this.

	If you don't use assigned numbers then when your device is submitted it will
	be given an assigned number even if that is different from values you may
	have shipped to customers before.

	Who To Submit Drivers To
	------------------------

	Linux 2.0:
	No new drivers are accepted for this kernel tree.

	Linux 2.2:
	No new drivers are accepted for this kernel tree.

	Linux 2.4:
	If the code area has a general maintainer then please submit it to
	the maintainer listed in MAINTAINERS in the kernel file. If the
	maintainer does not respond or you cannot find the appropriate
	maintainer then please contact Willy Tarreau <w@1wt.eu>.

	Linux 2.6 and upper:
	The same rules apply as 2.4 except that you should follow linux-kernel
	to track changes in API's. The final contact point for Linux 2.6+
	submissions is Andrew Morton.

	What Criteria Determine Acceptance
	----------------------------------

	Licensing:
	The code must be released to us under the
	GNU General Public License. If you wish the driver to be
	useful to other communities such as BSD you may release
	under multiple licenses. If you choose to release under
	licenses other than the GPL, you should include your
	rationale for your license choices in your cover letter.
	See accepted licenses at include/linux/module.h

	Copyright:
	The copyright owner must agree to use of GPL.
	It's best if the submitter and copyright owner
	are the same person/entity. If not, the name of
	the person/entity authorizing use of GPL should be
	listed in case it's necessary to verify the will of
	the copyright owner.

	Interfaces:
	If your driver uses existing interfaces and behaves like
	other drivers in the same class it will be much more likely
	to be accepted than if it invents gratuitous new ones.
	If you need to implement a common API over Linux and NT
	drivers do it in userspace.

	Code:
	Please use the Linux style of code formatting as documented
	in :ref:`Documentation/process/coding-style.rst <codingStyle>`.
	If you have sections of code
	that need to be in other formats, for example because they
	are shared with a windows driver kit and you want to
	maintain them just once separate them out nicely and note
	this fact.

	Portability:
	Pointers are not always 32bits, not all computers are little
	endian, people do not all have floating point and you
	shouldn't use inline x86 assembler in your driver without
	careful thought. Pure x86 drivers generally are not popular.
	If you only have x86 hardware it is hard to test portability
	but it is easy to make sure the code can easily be made
	portable.

	Clarity:
	It helps if anyone can see how to fix the driver. It helps
	you because you get patches not bug reports. If you submit a
	driver that intentionally obfuscates how the hardware works
	it will go in the bitbucket.

	PM support:
	Since Linux is used on many portable and desktop systems, your
	driver is likely to be used on such a system and therefore it
	should support basic power management by implementing, if
	necessary, the .suspend and .resume methods used during the
	system-wide suspend and resume transitions. You should verify
	that your driver correctly handles the suspend and resume, but
	if you are unable to ensure that, please at least define the
	.suspend method returning the -ENOSYS ("Function not
	implemented") error. You should also try to make sure that your
	driver uses as little power as possible when it's not doing
	anything. For the driver testing instructions see
	Documentation/power/drivers-testing.rst and for a relatively
	complete overview of the power management issues related to
	drivers see :ref:`Documentation/driver-api/pm/devices.rst <driverapi_pm_devices>`.

	Control:
	In general if there is active maintenance of a driver by
	the author then patches will be redirected to them unless
	they are totally obvious and without need of checking.
	If you want to be the contact and update point for the
	driver it is a good idea to state this in the comments,
	and include an entry in MAINTAINERS for your driver.

	What Criteria Do Not Determine Acceptance
	-----------------------------------------

	Vendor:
	Being the hardware vendor and maintaining the driver is
	often a good thing. If there is a stable working driver from
	other people already in the tree don't expect 'we are the
	vendor' to get your driver chosen. Ideally work with the
	existing driver author to build a single perfect driver.

	Author:
	It doesn't matter if a large Linux company wrote the driver,
	or you did. Nobody has any special access to the kernel
	tree. Anyone who tells you otherwise isn't telling the
	whole story.


	Resources
	---------

	Linux kernel master tree:
	ftp.\ country_code\ .kernel.org:/pub/linux/kernel/...

	where country_code == your country code, such as
	us, uk, fr, etc.

	https://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git

	Linux kernel mailing list:
	linux-kernel@vger.kernel.org
	[mail majordomo@vger.kernel.org to subscribe]

	Linux Device Drivers, Third Edition (covers 2.6.10):
	https://lwn.net/Kernel/LDD3/ (free version)

	LWN.net:
	Weekly summary of kernel development activity - https://lwn.net/

	2.6 API changes:

	https://lwn.net/Articles/2.6-kernel-api/

	Porting drivers from prior kernels to 2.6:

	https://lwn.net/Articles/driver-porting/

	KernelNewbies:
	Documentation and assistance for new kernel programmers

	https://kernelnewbies.org/

	Linux USB project:
	http://www.linux-usb.org/

	How to NOT write kernel driver by Arjan van de Ven:
	https://landley.net/kdocs/ols/2002/ols2002-pages-545-555.pdf

	Kernel Janitor:
	https://kernelnewbies.org/KernelJanitors

	GIT, Fast Version Control System:
	https://git-scm.com/