1.. _submittingdrivers: 2 3Submitting Drivers For The Linux Kernel 4======================================= 5 6This document is intended to explain how to submit device drivers to the 7various kernel trees. Note that if you are interested in video card drivers 8you should probably talk to XFree86 (http://www.xfree86.org/) and/or X.Org 9(http://x.org/) instead. 10 11Also read the Documentation/SubmittingPatches document. 12 13 14Allocating Device Numbers 15------------------------- 16 17Major and minor numbers for block and character devices are allocated 18by the Linux assigned name and number authority (currently this is 19Torben Mathiasen). The site is http://www.lanana.org/. This 20also deals with allocating numbers for devices that are not going to 21be submitted to the mainstream kernel. 22See Documentation/devices.txt for more information on this. 23 24If you don't use assigned numbers then when your device is submitted it will 25be given an assigned number even if that is different from values you may 26have shipped to customers before. 27 28Who To Submit Drivers To 29------------------------ 30 31Linux 2.0: 32 No new drivers are accepted for this kernel tree. 33 34Linux 2.2: 35 No new drivers are accepted for this kernel tree. 36 37Linux 2.4: 38 If the code area has a general maintainer then please submit it to 39 the maintainer listed in MAINTAINERS in the kernel file. If the 40 maintainer does not respond or you cannot find the appropriate 41 maintainer then please contact Willy Tarreau <w@1wt.eu>. 42 43Linux 2.6 and upper: 44 The same rules apply as 2.4 except that you should follow linux-kernel 45 to track changes in API's. The final contact point for Linux 2.6+ 46 submissions is Andrew Morton. 47 48What Criteria Determine Acceptance 49---------------------------------- 50 51Licensing: 52 The code must be released to us under the 53 GNU General Public License. We don't insist on any kind 54 of exclusive GPL licensing, and if you wish the driver 55 to be useful to other communities such as BSD you may well 56 wish to release under multiple licenses. 57 See accepted licenses at include/linux/module.h 58 59Copyright: 60 The copyright owner must agree to use of GPL. 61 It's best if the submitter and copyright owner 62 are the same person/entity. If not, the name of 63 the person/entity authorizing use of GPL should be 64 listed in case it's necessary to verify the will of 65 the copyright owner. 66 67Interfaces: 68 If your driver uses existing interfaces and behaves like 69 other drivers in the same class it will be much more likely 70 to be accepted than if it invents gratuitous new ones. 71 If you need to implement a common API over Linux and NT 72 drivers do it in userspace. 73 74Code: 75 Please use the Linux style of code formatting as documented 76 in :ref:`Documentation/CodingStyle <codingStyle>`. 77 If you have sections of code 78 that need to be in other formats, for example because they 79 are shared with a windows driver kit and you want to 80 maintain them just once separate them out nicely and note 81 this fact. 82 83Portability: 84 Pointers are not always 32bits, not all computers are little 85 endian, people do not all have floating point and you 86 shouldn't use inline x86 assembler in your driver without 87 careful thought. Pure x86 drivers generally are not popular. 88 If you only have x86 hardware it is hard to test portability 89 but it is easy to make sure the code can easily be made 90 portable. 91 92Clarity: 93 It helps if anyone can see how to fix the driver. It helps 94 you because you get patches not bug reports. If you submit a 95 driver that intentionally obfuscates how the hardware works 96 it will go in the bitbucket. 97 98PM support: 99 Since Linux is used on many portable and desktop systems, your 100 driver is likely to be used on such a system and therefore it 101 should support basic power management by implementing, if 102 necessary, the .suspend and .resume methods used during the 103 system-wide suspend and resume transitions. You should verify 104 that your driver correctly handles the suspend and resume, but 105 if you are unable to ensure that, please at least define the 106 .suspend method returning the -ENOSYS ("Function not 107 implemented") error. You should also try to make sure that your 108 driver uses as little power as possible when it's not doing 109 anything. For the driver testing instructions see 110 Documentation/power/drivers-testing.txt and for a relatively 111 complete overview of the power management issues related to 112 drivers see Documentation/power/devices.txt . 113 114Control: 115 In general if there is active maintenance of a driver by 116 the author then patches will be redirected to them unless 117 they are totally obvious and without need of checking. 118 If you want to be the contact and update point for the 119 driver it is a good idea to state this in the comments, 120 and include an entry in MAINTAINERS for your driver. 121 122What Criteria Do Not Determine Acceptance 123----------------------------------------- 124 125Vendor: 126 Being the hardware vendor and maintaining the driver is 127 often a good thing. If there is a stable working driver from 128 other people already in the tree don't expect 'we are the 129 vendor' to get your driver chosen. Ideally work with the 130 existing driver author to build a single perfect driver. 131 132Author: 133 It doesn't matter if a large Linux company wrote the driver, 134 or you did. Nobody has any special access to the kernel 135 tree. Anyone who tells you otherwise isn't telling the 136 whole story. 137 138 139Resources 140--------- 141 142Linux kernel master tree: 143 ftp.\ *country_code*\ .kernel.org:/pub/linux/kernel/... 144 145 where *country_code* == your country code, such as 146 **us**, **uk**, **fr**, etc. 147 148 http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git 149 150Linux kernel mailing list: 151 linux-kernel@vger.kernel.org 152 [mail majordomo@vger.kernel.org to subscribe] 153 154Linux Device Drivers, Third Edition (covers 2.6.10): 155 http://lwn.net/Kernel/LDD3/ (free version) 156 157LWN.net: 158 Weekly summary of kernel development activity - http://lwn.net/ 159 160 2.6 API changes: 161 162 http://lwn.net/Articles/2.6-kernel-api/ 163 164 Porting drivers from prior kernels to 2.6: 165 166 http://lwn.net/Articles/driver-porting/ 167 168KernelNewbies: 169 Documentation and assistance for new kernel programmers 170 171 http://kernelnewbies.org/ 172 173Linux USB project: 174 http://www.linux-usb.org/ 175 176How to NOT write kernel driver by Arjan van de Ven: 177 http://www.fenrus.org/how-to-not-write-a-device-driver-paper.pdf 178 179Kernel Janitor: 180 http://kernelnewbies.org/KernelJanitors 181 182GIT, Fast Version Control System: 183 http://git-scm.com/ 184