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 11.. note:: 12 13 This document is old and has seen little maintenance in recent years; it 14 should probably be updated or, perhaps better, just deleted. Most of 15 what is here can be found in the other development documents anyway. 16 17 Oh, and we don't really recommend submitting changes to XFree86 :) 18 19Also read the Documentation/process/submitting-patches.rst document. 20 21 22Allocating Device Numbers 23------------------------- 24 25Major and minor numbers for block and character devices are allocated 26by the Linux assigned name and number authority (currently this is 27Torben Mathiasen). The site is http://www.lanana.org/. This 28also deals with allocating numbers for devices that are not going to 29be submitted to the mainstream kernel. 30See Documentation/admin-guide/devices.rst for more information on this. 31 32If you don't use assigned numbers then when your device is submitted it will 33be given an assigned number even if that is different from values you may 34have shipped to customers before. 35 36Who To Submit Drivers To 37------------------------ 38 39Linux 2.0: 40 No new drivers are accepted for this kernel tree. 41 42Linux 2.2: 43 No new drivers are accepted for this kernel tree. 44 45Linux 2.4: 46 If the code area has a general maintainer then please submit it to 47 the maintainer listed in MAINTAINERS in the kernel file. If the 48 maintainer does not respond or you cannot find the appropriate 49 maintainer then please contact Willy Tarreau <w@1wt.eu>. 50 51Linux 2.6 and upper: 52 The same rules apply as 2.4 except that you should follow linux-kernel 53 to track changes in API's. The final contact point for Linux 2.6+ 54 submissions is Andrew Morton. 55 56What Criteria Determine Acceptance 57---------------------------------- 58 59Licensing: 60 The code must be released to us under the 61 GNU General Public License. We don't insist on any kind 62 of exclusive GPL licensing, and if you wish the driver 63 to be useful to other communities such as BSD you may well 64 wish to release under multiple licenses. 65 See accepted licenses at include/linux/module.h 66 67Copyright: 68 The copyright owner must agree to use of GPL. 69 It's best if the submitter and copyright owner 70 are the same person/entity. If not, the name of 71 the person/entity authorizing use of GPL should be 72 listed in case it's necessary to verify the will of 73 the copyright owner. 74 75Interfaces: 76 If your driver uses existing interfaces and behaves like 77 other drivers in the same class it will be much more likely 78 to be accepted than if it invents gratuitous new ones. 79 If you need to implement a common API over Linux and NT 80 drivers do it in userspace. 81 82Code: 83 Please use the Linux style of code formatting as documented 84 in :ref:`Documentation/process/coding-style.rst <codingStyle>`. 85 If you have sections of code 86 that need to be in other formats, for example because they 87 are shared with a windows driver kit and you want to 88 maintain them just once separate them out nicely and note 89 this fact. 90 91Portability: 92 Pointers are not always 32bits, not all computers are little 93 endian, people do not all have floating point and you 94 shouldn't use inline x86 assembler in your driver without 95 careful thought. Pure x86 drivers generally are not popular. 96 If you only have x86 hardware it is hard to test portability 97 but it is easy to make sure the code can easily be made 98 portable. 99 100Clarity: 101 It helps if anyone can see how to fix the driver. It helps 102 you because you get patches not bug reports. If you submit a 103 driver that intentionally obfuscates how the hardware works 104 it will go in the bitbucket. 105 106PM support: 107 Since Linux is used on many portable and desktop systems, your 108 driver is likely to be used on such a system and therefore it 109 should support basic power management by implementing, if 110 necessary, the .suspend and .resume methods used during the 111 system-wide suspend and resume transitions. You should verify 112 that your driver correctly handles the suspend and resume, but 113 if you are unable to ensure that, please at least define the 114 .suspend method returning the -ENOSYS ("Function not 115 implemented") error. You should also try to make sure that your 116 driver uses as little power as possible when it's not doing 117 anything. For the driver testing instructions see 118 Documentation/power/drivers-testing.txt and for a relatively 119 complete overview of the power management issues related to 120 drivers see Documentation/driver-api/pm/devices.rst. 121 122Control: 123 In general if there is active maintenance of a driver by 124 the author then patches will be redirected to them unless 125 they are totally obvious and without need of checking. 126 If you want to be the contact and update point for the 127 driver it is a good idea to state this in the comments, 128 and include an entry in MAINTAINERS for your driver. 129 130What Criteria Do Not Determine Acceptance 131----------------------------------------- 132 133Vendor: 134 Being the hardware vendor and maintaining the driver is 135 often a good thing. If there is a stable working driver from 136 other people already in the tree don't expect 'we are the 137 vendor' to get your driver chosen. Ideally work with the 138 existing driver author to build a single perfect driver. 139 140Author: 141 It doesn't matter if a large Linux company wrote the driver, 142 or you did. Nobody has any special access to the kernel 143 tree. Anyone who tells you otherwise isn't telling the 144 whole story. 145 146 147Resources 148--------- 149 150Linux kernel master tree: 151 ftp.\ *country_code*\ .kernel.org:/pub/linux/kernel/... 152 153 where *country_code* == your country code, such as 154 **us**, **uk**, **fr**, etc. 155 156 http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git 157 158Linux kernel mailing list: 159 linux-kernel@vger.kernel.org 160 [mail majordomo@vger.kernel.org to subscribe] 161 162Linux Device Drivers, Third Edition (covers 2.6.10): 163 http://lwn.net/Kernel/LDD3/ (free version) 164 165LWN.net: 166 Weekly summary of kernel development activity - http://lwn.net/ 167 168 2.6 API changes: 169 170 http://lwn.net/Articles/2.6-kernel-api/ 171 172 Porting drivers from prior kernels to 2.6: 173 174 http://lwn.net/Articles/driver-porting/ 175 176KernelNewbies: 177 Documentation and assistance for new kernel programmers 178 179 http://kernelnewbies.org/ 180 181Linux USB project: 182 http://www.linux-usb.org/ 183 184How to NOT write kernel driver by Arjan van de Ven: 185 http://www.fenrus.org/how-to-not-write-a-device-driver-paper.pdf 186 187Kernel Janitor: 188 http://kernelnewbies.org/KernelJanitors 189 190GIT, Fast Version Control System: 191 http://git-scm.com/ 192
