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 Marcelo Tosatti
  40         <marcelo.tosatti@cyclades.com>.
  41
  42 Linux 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
  47 What Criteria Determine Acceptance
  48 ----------------------------------
  49
  50 Licensing:      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
  57 Copyright:      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
  64 Interfaces:     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
  70 Code:           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
  77 Portability:    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
  85 Clarity:        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
  90 PM 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
 105 Control:        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
 112 What Criteria Do Not Determine Acceptance
 113 -----------------------------------------
 114
 115 Vendor:         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
 121 Author:         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
 127 Resources
 128 ---------
 129
 130 Linux kernel master tree:
 131         ftp.??.kernel.org:/pub/linux/kernel/...
 132         ?? == your country code, such as "us", "uk", "fr", etc.
 133
 134 Linux kernel mailing list:
 135         linux-kernel@vger.kernel.org
 136         [mail majordomo@vger.kernel.org to subscribe]
 137
 138 Linux Device Drivers, Third Edition (covers 2.6.10):
 139         http://lwn.net/Kernel/LDD3/  (free version)
 140
 141 LWN.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
 148 KernelTrap:
 149         Occasional Linux kernel articles and developer interviews
 150         http://kerneltrap.org/
 151
 152 KernelNewbies:
 153         Documentation and assistance for new kernel programmers
 154         http://kernelnewbies.org/
 155
 156 Linux USB project:
 157         http://www.linux-usb.org/
 158
 159 How 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
 162 Kernel Janitor:
 163         http://janitor.kernelnewbies.org/