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 (https://www.xfree86.org/) and/or X.Org 9(https://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 :ref:`Documentation/process/submitting-patches.rst <submittingpatches>` 20document. 21 22 23Allocating Device Numbers 24------------------------- 25 26Major and minor numbers for block and character devices are allocated 27by the Linux assigned name and number authority (currently this is 28Torben Mathiasen). The site is https://www.lanana.org/. This 29also deals with allocating numbers for devices that are not going to 30be submitted to the mainstream kernel. 31See :ref:`Documentation/admin-guide/devices.rst <admin_devices>` 32for more information on this. 33 34If you don't use assigned numbers then when your device is submitted it will 35be given an assigned number even if that is different from values you may 36have shipped to customers before. 37 38Who To Submit Drivers To 39------------------------ 40 41Linux 2.0: 42 No new drivers are accepted for this kernel tree. 43 44Linux 2.2: 45 No new drivers are accepted for this kernel tree. 46 47Linux 2.4: 48 If the code area has a general maintainer then please submit it to 49 the maintainer listed in MAINTAINERS in the kernel file. If the 50 maintainer does not respond or you cannot find the appropriate 51 maintainer then please contact Willy Tarreau <w@1wt.eu>. 52 53Linux 2.6 and upper: 54 The same rules apply as 2.4 except that you should follow linux-kernel 55 to track changes in API's. The final contact point for Linux 2.6+ 56 submissions is Andrew Morton. 57 58What Criteria Determine Acceptance 59---------------------------------- 60 61Licensing: 62 The code must be released to us under the 63 GNU General Public License. If you wish the driver to be 64 useful to other communities such as BSD you may release 65 under multiple licenses. If you choose to release under 66 licenses other than the GPL, you should include your 67 rationale for your license choices in your cover letter. 68 See accepted licenses at include/linux/module.h 69 70Copyright: 71 The copyright owner must agree to use of GPL. 72 It's best if the submitter and copyright owner 73 are the same person/entity. If not, the name of 74 the person/entity authorizing use of GPL should be 75 listed in case it's necessary to verify the will of 76 the copyright owner. 77 78Interfaces: 79 If your driver uses existing interfaces and behaves like 80 other drivers in the same class it will be much more likely 81 to be accepted than if it invents gratuitous new ones. 82 If you need to implement a common API over Linux and NT 83 drivers do it in userspace. 84 85Code: 86 Please use the Linux style of code formatting as documented 87 in :ref:`Documentation/process/coding-style.rst <codingStyle>`. 88 If you have sections of code 89 that need to be in other formats, for example because they 90 are shared with a windows driver kit and you want to 91 maintain them just once separate them out nicely and note 92 this fact. 93 94Portability: 95 Pointers are not always 32bits, not all computers are little 96 endian, people do not all have floating point and you 97 shouldn't use inline x86 assembler in your driver without 98 careful thought. Pure x86 drivers generally are not popular. 99 If you only have x86 hardware it is hard to test portability 100 but it is easy to make sure the code can easily be made 101 portable. 102 103Clarity: 104 It helps if anyone can see how to fix the driver. It helps 105 you because you get patches not bug reports. If you submit a 106 driver that intentionally obfuscates how the hardware works 107 it will go in the bitbucket. 108 109PM support: 110 Since Linux is used on many portable and desktop systems, your 111 driver is likely to be used on such a system and therefore it 112 should support basic power management by implementing, if 113 necessary, the .suspend and .resume methods used during the 114 system-wide suspend and resume transitions. You should verify 115 that your driver correctly handles the suspend and resume, but 116 if you are unable to ensure that, please at least define the 117 .suspend method returning the -ENOSYS ("Function not 118 implemented") error. You should also try to make sure that your 119 driver uses as little power as possible when it's not doing 120 anything. For the driver testing instructions see 121 Documentation/power/drivers-testing.rst and for a relatively 122 complete overview of the power management issues related to 123 drivers see :ref:`Documentation/driver-api/pm/devices.rst <driverapi_pm_devices>`. 124 125Control: 126 In general if there is active maintenance of a driver by 127 the author then patches will be redirected to them unless 128 they are totally obvious and without need of checking. 129 If you want to be the contact and update point for the 130 driver it is a good idea to state this in the comments, 131 and include an entry in MAINTAINERS for your driver. 132 133What Criteria Do Not Determine Acceptance 134----------------------------------------- 135 136Vendor: 137 Being the hardware vendor and maintaining the driver is 138 often a good thing. If there is a stable working driver from 139 other people already in the tree don't expect 'we are the 140 vendor' to get your driver chosen. Ideally work with the 141 existing driver author to build a single perfect driver. 142 143Author: 144 It doesn't matter if a large Linux company wrote the driver, 145 or you did. Nobody has any special access to the kernel 146 tree. Anyone who tells you otherwise isn't telling the 147 whole story. 148 149 150Resources 151--------- 152 153Linux kernel master tree: 154 ftp.\ *country_code*\ .kernel.org:/pub/linux/kernel/... 155 156 where *country_code* == your country code, such as 157 **us**, **uk**, **fr**, etc. 158 159 https://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git 160 161Linux kernel mailing list: 162 linux-kernel@vger.kernel.org 163 [mail majordomo@vger.kernel.org to subscribe] 164 165Linux Device Drivers, Third Edition (covers 2.6.10): 166 https://lwn.net/Kernel/LDD3/ (free version) 167 168LWN.net: 169 Weekly summary of kernel development activity - https://lwn.net/ 170 171 2.6 API changes: 172 173 https://lwn.net/Articles/2.6-kernel-api/ 174 175 Porting drivers from prior kernels to 2.6: 176 177 https://lwn.net/Articles/driver-porting/ 178 179KernelNewbies: 180 Documentation and assistance for new kernel programmers 181 182 https://kernelnewbies.org/ 183 184Linux USB project: 185 http://www.linux-usb.org/ 186 187How to NOT write kernel driver by Arjan van de Ven: 188 http://www.fenrus.org/how-to-not-write-a-device-driver-paper.pdf 189 190Kernel Janitor: 191 https://kernelnewbies.org/KernelJanitors 192 193GIT, Fast Version Control System: 194 https://git-scm.com/ 195