linux/Documentation/SubmittingDrivers
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   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
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