Documentation/process/submitting-drivers.rst - third_party/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 (http://www.xfree86.org/) and/or X.Org

            
            (http://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 Documentation/process/submitting-patches.rst 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 http://www.lanana.org/. This

            
            also deals with allocating numbers for devices that are not going to

            
            be submitted to the mainstream kernel.

            
            See Documentation/admin-guide/devices.rst 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. We don't insist on any kind

            
            		of exclusive GPL licensing, and if you wish the driver

            
            		to be useful to other communities such as BSD you may well

            
            		wish to release under multiple licenses.

            
            		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.txt and for a relatively

            
            		complete overview of the power management issues related to

            
            		drivers see Documentation/driver-api/pm/devices.rst.


            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.


            	http://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):

            
            	http://lwn.net/Kernel/LDD3/  (free version)


            LWN.net:

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


            	2.6 API changes:


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


            	Porting drivers from prior kernels to 2.6:


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


            KernelNewbies:

            
            	Documentation and assistance for new kernel programmers


            		http://kernelnewbies.org/


            Linux USB project:

            
            	http://www.linux-usb.org/


            How to NOT write kernel driver by Arjan van de Ven:

            
            	http://www.fenrus.org/how-to-not-write-a-device-driver-paper.pdf


            Kernel Janitor:

            
            	http://kernelnewbies.org/KernelJanitors


            GIT, Fast Version Control System:

            
            	http://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 (http://www.xfree86.org/) and/or X.Org
	(http://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 Documentation/process/submitting-patches.rst 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 http://www.lanana.org/. This
	also deals with allocating numbers for devices that are not going to
	be submitted to the mainstream kernel.
	See Documentation/admin-guide/devices.rst 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. We don't insist on any kind
	of exclusive GPL licensing, and if you wish the driver
	to be useful to other communities such as BSD you may well
	wish to release under multiple licenses.
	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.txt and for a relatively
	complete overview of the power management issues related to
	drivers see Documentation/driver-api/pm/devices.rst.

	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.

	http://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):
	http://lwn.net/Kernel/LDD3/ (free version)

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

	2.6 API changes:

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

	Porting drivers from prior kernels to 2.6:

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

	KernelNewbies:
	Documentation and assistance for new kernel programmers

	http://kernelnewbies.org/

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

	How to NOT write kernel driver by Arjan van de Ven:
	http://www.fenrus.org/how-to-not-write-a-device-driver-paper.pdf

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

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