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 :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 http://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. We don't insist on any kind 64 of exclusive GPL licensing, and if you wish the driver 65 to be useful to other communities such as BSD you may well 66 wish to release under multiple licenses. 67 See accepted licenses at include/linux/module.h 68 69Copyright: 70 The copyright owner must agree to use of GPL. 71 It's best if the submitter and copyright owner 72 are the same person/entity. If not, the name of 73 the person/entity authorizing use of GPL should be 74 listed in case it's necessary to verify the will of 75 the copyright owner. 76 77Interfaces: 78 If your driver uses existing interfaces and behaves like 79 other drivers in the same class it will be much more likely 80 to be accepted than if it invents gratuitous new ones. 81 If you need to implement a common API over Linux and NT 82 drivers do it in userspace. 83 84Code: 85 Please use the Linux style of code formatting as documented 86 in :ref:`Documentation/process/coding-style.rst <codingStyle>`. 87 If you have sections of code 88 that need to be in other formats, for example because they 89 are shared with a windows driver kit and you want to 90 maintain them just once separate them out nicely and note 91 this fact. 92 93Portability: 94 Pointers are not always 32bits, not all computers are little 95 endian, people do not all have floating point and you 96 shouldn't use inline x86 assembler in your driver without 97 careful thought. Pure x86 drivers generally are not popular. 98 If you only have x86 hardware it is hard to test portability 99 but it is easy to make sure the code can easily be made 100 portable. 101 102Clarity: 103 It helps if anyone can see how to fix the driver. It helps 104 you because you get patches not bug reports. If you submit a 105 driver that intentionally obfuscates how the hardware works 106 it will go in the bitbucket. 107 108PM support: 109 Since Linux is used on many portable and desktop systems, your 110 driver is likely to be used on such a system and therefore it 111 should support basic power management by implementing, if 112 necessary, the .suspend and .resume methods used during the 113 system-wide suspend and resume transitions. You should verify 114 that your driver correctly handles the suspend and resume, but 115 if you are unable to ensure that, please at least define the 116 .suspend method returning the -ENOSYS ("Function not 117 implemented") error. You should also try to make sure that your 118 driver uses as little power as possible when it's not doing 119 anything. For the driver testing instructions see 120 Documentation/power/drivers-testing.rst and for a relatively 121 complete overview of the power management issues related to 122 drivers see :ref:`Documentation/driver-api/pm/devices.rst <driverapi_pm_devices>`. 123 124Control: 125 In general if there is active maintenance of a driver by 126 the author then patches will be redirected to them unless 127 they are totally obvious and without need of checking. 128 If you want to be the contact and update point for the 129 driver it is a good idea to state this in the comments, 130 and include an entry in MAINTAINERS for your driver. 131 132What Criteria Do Not Determine Acceptance 133----------------------------------------- 134 135Vendor: 136 Being the hardware vendor and maintaining the driver is 137 often a good thing. If there is a stable working driver from 138 other people already in the tree don't expect 'we are the 139 vendor' to get your driver chosen. Ideally work with the 140 existing driver author to build a single perfect driver. 141 142Author: 143 It doesn't matter if a large Linux company wrote the driver, 144 or you did. Nobody has any special access to the kernel 145 tree. Anyone who tells you otherwise isn't telling the 146 whole story. 147 148 149Resources 150--------- 151 152Linux kernel master tree: 153 ftp.\ *country_code*\ .kernel.org:/pub/linux/kernel/... 154 155 where *country_code* == your country code, such as 156 **us**, **uk**, **fr**, etc. 157 158 http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git 159 160Linux kernel mailing list: 161 linux-kernel@vger.kernel.org 162 [mail majordomo@vger.kernel.org to subscribe] 163 164Linux Device Drivers, Third Edition (covers 2.6.10): 165 http://lwn.net/Kernel/LDD3/ (free version) 166 167LWN.net: 168 Weekly summary of kernel development activity - http://lwn.net/ 169 170 2.6 API changes: 171 172 http://lwn.net/Articles/2.6-kernel-api/ 173 174 Porting drivers from prior kernels to 2.6: 175 176 http://lwn.net/Articles/driver-porting/ 177 178KernelNewbies: 179 Documentation and assistance for new kernel programmers 180 181 http://kernelnewbies.org/ 182 183Linux USB project: 184 http://www.linux-usb.org/ 185 186How to NOT write kernel driver by Arjan van de Ven: 187 http://www.fenrus.org/how-to-not-write-a-device-driver-paper.pdf 188 189Kernel Janitor: 190 http://kernelnewbies.org/KernelJanitors 191 192GIT, Fast Version Control System: 193 http://git-scm.com/ 194
