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 Marcelo Tosatti 40 <marcelo.tosatti@cyclades.com>. 41 42Linux 2.6: 43 The same rules apply as 2.4 except that you should follow linux-kernel 44 to track changes in API's. The final contact point for Linux 2.6 45 submissions is Andrew Morton <akpm@osdl.org>. 46 47What Criteria Determine Acceptance 48---------------------------------- 49 50Licensing: The code must be released to us under the 51 GNU General Public License. We don't insist on any kind 52 of exclusive GPL licensing, and if you wish the driver 53 to be useful to other communities such as BSD you may well 54 wish to release under multiple licenses. 55 See accepted licenses at include/linux/module.h 56 57Copyright: The copyright owner must agree to use of GPL. 58 It's best if the submitter and copyright owner 59 are the same person/entity. If not, the name of 60 the person/entity authorizing use of GPL should be 61 listed in case it's necessary to verify the will of 62 the copyright owner. 63 64Interfaces: If your driver uses existing interfaces and behaves like 65 other drivers in the same class it will be much more likely 66 to be accepted than if it invents gratuitous new ones. 67 If you need to implement a common API over Linux and NT 68 drivers do it in userspace. 69 70Code: Please use the Linux style of code formatting as documented 71 in Documentation/CodingStyle. If you have sections of code 72 that need to be in other formats, for example because they 73 are shared with a windows driver kit and you want to 74 maintain them just once separate them out nicely and note 75 this fact. 76 77Portability: Pointers are not always 32bits, not all computers are little 78 endian, people do not all have floating point and you 79 shouldn't use inline x86 assembler in your driver without 80 careful thought. Pure x86 drivers generally are not popular. 81 If you only have x86 hardware it is hard to test portability 82 but it is easy to make sure the code can easily be made 83 portable. 84 85Clarity: It helps if anyone can see how to fix the driver. It helps 86 you because you get patches not bug reports. If you submit a 87 driver that intentionally obfuscates how the hardware works 88 it will go in the bitbucket. 89 90PM support: Since Linux is used on many portable and desktop systems, your 91 driver is likely to be used on such a system and therefore it 92 should support basic power management by implementing, if 93 necessary, the .suspend and .resume methods used during the 94 system-wide suspend and resume transitions. You should verify 95 that your driver correctly handles the suspend and resume, but 96 if you are unable to ensure that, please at least define the 97 .suspend method returning the -ENOSYS ("Function not 98 implemented") error. You should also try to make sure that your 99 driver uses as little power as possible when it's not doing 100 anything. For the driver testing instructions see 101 Documentation/power/drivers-testing.txt and for a relatively 102 complete overview of the power management issues related to 103 drivers see Documentation/power/devices.txt . 104 105Control: In general if there is active maintainance of a driver by 106 the author then patches will be redirected to them unless 107 they are totally obvious and without need of checking. 108 If you want to be the contact and update point for the 109 driver it is a good idea to state this in the comments, 110 and include an entry in MAINTAINERS for your driver. 111 112What Criteria Do Not Determine Acceptance 113----------------------------------------- 114 115Vendor: Being the hardware vendor and maintaining the driver is 116 often a good thing. If there is a stable working driver from 117 other people already in the tree don't expect 'we are the 118 vendor' to get your driver chosen. Ideally work with the 119 existing driver author to build a single perfect driver. 120 121Author: It doesn't matter if a large Linux company wrote the driver, 122 or you did. Nobody has any special access to the kernel 123 tree. Anyone who tells you otherwise isn't telling the 124 whole story. 125 126 127Resources 128--------- 129 130Linux kernel master tree: 131 ftp.??.kernel.org:/pub/linux/kernel/... 132 ?? == your country code, such as "us", "uk", "fr", etc. 133 134Linux kernel mailing list: 135 linux-kernel@vger.kernel.org 136 [mail majordomo@vger.kernel.org to subscribe] 137 138Linux Device Drivers, Third Edition (covers 2.6.10): 139 http://lwn.net/Kernel/LDD3/ (free version) 140 141LWN.net: 142 Weekly summary of kernel development activity - http://lwn.net/ 143 2.6 API changes: 144 http://lwn.net/Articles/2.6-kernel-api/ 145 Porting drivers from prior kernels to 2.6: 146 http://lwn.net/Articles/driver-porting/ 147 148KernelTrap: 149 Occasional Linux kernel articles and developer interviews 150 http://kerneltrap.org/ 151 152KernelNewbies: 153 Documentation and assistance for new kernel programmers 154 http://kernelnewbies.org/ 155 156Linux USB project: 157 http://www.linux-usb.org/ 158 159How to NOT write kernel driver by Arjan van de Ven: 160 http://www.fenrus.org/how-to-not-write-a-device-driver-paper.pdf 161 162Kernel Janitor: 163 http://janitor.kernelnewbies.org/ 164