1Submitting Drivers For The Linux Kernel
2---------------------------------------
3
4This document is intended to explain how to submit device drivers to the
5various kernel trees. Note that if you are interested in video card drivers
6you should probably talk to XFree86 (http://www.xfree86.org/) and/or X.Org
7(http://x.org/) instead.
8
9Also read the Documentation/SubmittingPatches document.
10
11
12Allocating Device Numbers
13-------------------------
14
15Major and minor numbers for block and character devices are allocated
16by the Linux assigned name and number authority (currently this is
17Torben Mathiasen). The site is http://www.lanana.org/. This
18also deals with allocating numbers for devices that are not going to
19be submitted to the mainstream kernel.
20See Documentation/devices.txt for more information on this.
21
22If you don't use assigned numbers then when your device is submitted it will
23be given an assigned number even if that is different from values you may
24have shipped to customers before.
25
26Who To Submit Drivers To
27------------------------
28
29Linux 2.0:
30	No new drivers are accepted for this kernel tree.
31
32Linux 2.2:
33	No new drivers are accepted for this kernel tree.
34
35Linux 2.4:
36	If the code area has a general maintainer then please submit it to
37	the maintainer listed in MAINTAINERS in the kernel file. If the
38	maintainer does not respond or you cannot find the appropriate
39	maintainer then please contact Willy Tarreau <w@1wt.eu>.
40
41Linux 2.6:
42	The same rules apply as 2.4 except that you should follow linux-kernel
43	to track changes in API's. The final contact point for Linux 2.6
44	submissions is Andrew Morton <akpm@osdl.org>.
45
46What Criteria Determine Acceptance
47----------------------------------
48
49Licensing:	The code must be released to us under the
50		GNU General Public License. We don't insist on any kind
51		of exclusive GPL licensing, and if you wish the driver
52		to be useful to other communities such as BSD you may well
53		wish to release under multiple licenses.
54		See accepted licenses at include/linux/module.h
55
56Copyright:	The copyright owner must agree to use of GPL.
57		It's best if the submitter and copyright owner
58		are the same person/entity. If not, the name of
59		the person/entity authorizing use of GPL should be
60		listed in case it's necessary to verify the will of
61		the copyright owner.
62
63Interfaces:	If your driver uses existing interfaces and behaves like
64		other drivers in the same class it will be much more likely
65		to be accepted than if it invents gratuitous new ones.
66		If you need to implement a common API over Linux and NT
67		drivers do it in userspace.
68
69Code:		Please use the Linux style of code formatting as documented
70		in Documentation/CodingStyle. If you have sections of code
71		that need to be in other formats, for example because they
72		are shared with a windows driver kit and you want to
73		maintain them just once separate them out nicely and note
74		this fact.
75
76Portability:	Pointers are not always 32bits, not all computers are little
77		endian, people do not all have floating point and you
78		shouldn't use inline x86 assembler in your driver without
79		careful thought. Pure x86 drivers generally are not popular.
80		If you only have x86 hardware it is hard to test portability
81		but it is easy to make sure the code can easily be made
82		portable.
83
84Clarity:	It helps if anyone can see how to fix the driver. It helps
85		you because you get patches not bug reports. If you submit a
86		driver that intentionally obfuscates how the hardware works
87		it will go in the bitbucket.
88
89Control:	In general if there is active maintainance of a driver by
90		the author then patches will be redirected to them unless
91		they are totally obvious and without need of checking.
92		If you want to be the contact and update point for the
93		driver it is a good idea to state this in the comments,
94		and include an entry in MAINTAINERS for your driver.
95
96What Criteria Do Not Determine Acceptance
97-----------------------------------------
98
99Vendor:		Being the hardware vendor and maintaining the driver is
100		often a good thing. If there is a stable working driver from
101		other people already in the tree don't expect 'we are the
102		vendor' to get your driver chosen. Ideally work with the
103		existing driver author to build a single perfect driver.
104
105Author:		It doesn't matter if a large Linux company wrote the driver,
106		or you did. Nobody has any special access to the kernel
107		tree. Anyone who tells you otherwise isn't telling the
108		whole story.
109
110
111Resources
112---------
113
114Linux kernel master tree:
115	ftp.??.kernel.org:/pub/linux/kernel/...
116	?? == your country code, such as "us", "uk", "fr", etc.
117
118Linux kernel mailing list:
119	linux-kernel@vger.kernel.org
120	[mail majordomo@vger.kernel.org to subscribe]
121
122Linux Device Drivers, Third Edition (covers 2.6.10):
123	http://lwn.net/Kernel/LDD3/  (free version)
124
125LWN.net:
126	Weekly summary of kernel development activity - http://lwn.net/
127	2.6 API changes:
128		http://lwn.net/Articles/2.6-kernel-api/
129	Porting drivers from prior kernels to 2.6:
130		http://lwn.net/Articles/driver-porting/
131
132KernelTrap:
133	Occasional Linux kernel articles and developer interviews
134	http://kerneltrap.org/
135
136KernelNewbies:
137	Documentation and assistance for new kernel programmers
138	http://kernelnewbies.org/
139
140Linux USB project:
141	http://www.linux-usb.org/
142
143How to NOT write kernel driver by Arjan van de Ven:
144	http://www.fenrus.org/how-to-not-write-a-device-driver-paper.pdf
145
146Kernel Janitor:
147	http://janitor.kernelnewbies.org/
148