Documentation/SubmittingDrivers

   1 Submitting Drivers For The Linux Kernel
   2 ---------------------------------------
   3
   4 This document is intended to explain how to submit device drivers to the
   5 various kernel trees. Note that if you are interested in video card drivers
   6 you should probably talk to XFree86 (http://www.xfree86.org/) and/or X.Org
   7 (http://x.org/) instead.
   8
   9 Also read the Documentation/SubmittingPatches document.
  10
  11
  12 Allocating Device Numbers
  13 -------------------------
  14
  15 Major and minor numbers for block and character devices are allocated
  16 by the Linux assigned name and number authority (currently this is
  17 Torben Mathiasen). The site is http://www.lanana.org/. This
  18 also deals with allocating numbers for devices that are not going to
  19 be submitted to the mainstream kernel.
  20 See Documentation/devices.txt for more information on this.
  21
  22 If you don't use assigned numbers then when your device is submitted it will
  23 be given an assigned number even if that is different from values you may
  24 have shipped to customers before.
  25
  26 Who To Submit Drivers To
  27 ------------------------
  28
  29 Linux 2.0:
  30         No new drivers are accepted for this kernel tree.
  31
  32 Linux 2.2:
  33         No new drivers are accepted for this kernel tree.
  34
  35 Linux 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
  41 Linux 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
  46 What Criteria Determine Acceptance
  47 ----------------------------------
  48
  49 Licensing:      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
  56 Copyright:      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
  63 Interfaces:     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
  69 Code:           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
  76 Portability:    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
  84 Clarity:        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
  89 PM 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
 104 Control:        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
 111 What Criteria Do Not Determine Acceptance
 112 -----------------------------------------
 113
 114 Vendor:         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
 120 Author:         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
 126 Resources
 127 ---------
 128
 129 Linux 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
 135 Linux kernel mailing list:
 136         linux-kernel@vger.kernel.org
 137         [mail majordomo@vger.kernel.org to subscribe]
 138
 139 Linux Device Drivers, Third Edition (covers 2.6.10):
 140         http://lwn.net/Kernel/LDD3/  (free version)
 141
 142 LWN.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
 149 KernelNewbies:
 150         Documentation and assistance for new kernel programmers
 151         http://kernelnewbies.org/
 152
 153 Linux USB project:
 154         http://www.linux-usb.org/
 155
 156 How to NOT write kernel driver by Arjan van de Ven:
 157         http://www.fenrus.org/how-to-not-write-a-device-driver-paper.pdf
 158
 159 Kernel Janitor:
 160         http://kernelnewbies.org/KernelJanitors
 161
 162 GIT, Fast Version Control System:
 163         http://git-scm.com/