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. 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 89PM support: Since Linux is used on many portable and desktop systems, your 90 driver is likely to be used on such a system and therefore it 91 should support basic power management by implementing, if 92 necessary, the .suspend and .resume methods used during the 93 system-wide suspend and resume transitions. You should verify 94 that your driver correctly handles the suspend and resume, but 95 if you are unable to ensure that, please at least define the 96 .suspend method returning the -ENOSYS ("Function not 97 implemented") error. You should also try to make sure that your 98 driver uses as little power as possible when it's not doing 99 anything. For the driver testing instructions see 100 Documentation/power/drivers-testing.txt and for a relatively 101 complete overview of the power management issues related to 102 drivers see Documentation/power/devices.txt . 103 104Control: In general if there is active maintenance of a driver by 105 the author then patches will be redirected to them unless 106 they are totally obvious and without need of checking. 107 If you want to be the contact and update point for the 108 driver it is a good idea to state this in the comments, 109 and include an entry in MAINTAINERS for your driver. 110 111What Criteria Do Not Determine Acceptance 112----------------------------------------- 113 114Vendor: Being the hardware vendor and maintaining the driver is 115 often a good thing. If there is a stable working driver from 116 other people already in the tree don't expect 'we are the 117 vendor' to get your driver chosen. Ideally work with the 118 existing driver author to build a single perfect driver. 119 120Author: It doesn't matter if a large Linux company wrote the driver, 121 or you did. Nobody has any special access to the kernel 122 tree. Anyone who tells you otherwise isn't telling the 123 whole story. 124 125 126Resources 127--------- 128 129Linux kernel master tree: 130 ftp.??.kernel.org:/pub/linux/kernel/... 131 ?? == your country code, such as "us", "uk", "fr", etc. 132 133 http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git 134 135Linux kernel mailing list: 136 linux-kernel@vger.kernel.org 137 [mail majordomo@vger.kernel.org to subscribe] 138 139Linux Device Drivers, Third Edition (covers 2.6.10): 140 http://lwn.net/Kernel/LDD3/ (free version) 141 142LWN.net: 143 Weekly summary of kernel development activity - http://lwn.net/ 144 2.6 API changes: 145 http://lwn.net/Articles/2.6-kernel-api/ 146 Porting drivers from prior kernels to 2.6: 147 http://lwn.net/Articles/driver-porting/ 148 149KernelTrap: 150 Occasional Linux kernel articles and developer interviews 151 http://kerneltrap.org/ 152 153KernelNewbies: 154 Documentation and assistance for new kernel programmers 155 http://kernelnewbies.org/ 156 157Linux USB project: 158 http://www.linux-usb.org/ 159 160How to NOT write kernel driver by Arjan van de Ven: 161 http://www.fenrus.org/how-to-not-write-a-device-driver-paper.pdf 162 163Kernel Janitor: 164 http://kernelnewbies.org/KernelJanitors 165 166GIT, Fast Version Control System: 167 http://git-scm.com/ 168