Submitting Drivers For The Linux Kernel--------------------------------------- This document is intended to explain how to submit device drivers to thevarious kernel trees. Note that if you are interested in video card driversyou should probably talk to XFree86 (http://www.xfree86.org/) and/or X.Org(http://x.org/) instead. Also read the Documentation/SubmittingPatches document.  Allocating Device Numbers------------------------- Major and minor numbers for block and character devices are allocatedby the Linux assigned name and number authority (currently this isTorben Mathiasen). The site is http://www.lanana.org/. Thisalso deals with allocating numbers for devices that are not going tobe submitted to the mainstream kernel.See Documentation/devices.txt for more information on this. If you don't use assigned numbers then when your device is submitted it willbe given an assigned number even if that is different from values you mayhave 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:	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 <akpm@osdl.org>. 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 Documentation/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/power/devices.txt . Control:	In general if there is active maintainance 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.??.kernel.org:/pub/linux/kernel/...	?? == your country code, such as "us", "uk", "fr", etc. 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/ KernelTrap:	Occasional Linux kernel articles and developer interviews	http://kerneltrap.org/ 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://janitor.kernelnewbies.org/