FreeBSD/Linux Kernel Cross Reference
sys/Documentation/SubmittingDrivers

     Submitting Drivers For The Linux Kernel
     ---------------------------------------
     
     This document is intended to explain how to submit device drivers to the
     various kernel trees. Note that if you are interested in video card drivers
     you should probably talk to XFree86 (http://www.xfree86.org/) and/or X.Org
     (http://x.org/) instead.
     
     Also read the Documentation/SubmittingPatches document.
    
    
    Allocating Device Numbers
    -------------------------
    
    Major and minor numbers for block and character devices are allocated
    by the Linux assigned name and number authority (currently this is
    Torben Mathiasen). The site is http://www.lanana.org/. This
    also deals with allocating numbers for devices that are not going to
    be submitted to the mainstream kernel.
    See Documentation/devices.txt for more information on this.
    
    If you don't use assigned numbers then when your device is submitted it will
    be given an assigned number even if that is different from values you may
    have shipped to customers before.
    
    Who To Submit Drivers To
    ------------------------
    
    Linux 2.0:
            No new drivers are accepted for this kernel tree.
    
    Linux 2.2:
            No new drivers are accepted for this kernel tree.
    
    Linux 2.4:
            If the code area has a general maintainer then please submit it to
            the maintainer listed in MAINTAINERS in the kernel file. If the
            maintainer does not respond or you cannot find the appropriate
            maintainer then please contact Willy Tarreau <w@1wt.eu>.
    
    Linux 2.6:
            The same rules apply as 2.4 except that you should follow linux-kernel
            to track changes in API's. The final contact point for Linux 2.6
            submissions is Andrew Morton.
    
    What Criteria Determine Acceptance
    ----------------------------------
    
    Licensing:      The code must be released to us under the
                    GNU General Public License. We don't insist on any kind
                    of exclusive GPL licensing, and if you wish the driver
                    to be useful to other communities such as BSD you may well
                    wish to release under multiple licenses.
                    See accepted licenses at include/linux/module.h
    
    Copyright:      The copyright owner must agree to use of GPL.
                    It's best if the submitter and copyright owner
                    are the same person/entity. If not, the name of
                    the person/entity authorizing use of GPL should be
                    listed in case it's necessary to verify the will of
                    the copyright owner.
    
    Interfaces:     If your driver uses existing interfaces and behaves like
                    other drivers in the same class it will be much more likely
                    to be accepted than if it invents gratuitous new ones.
                    If you need to implement a common API over Linux and NT
                    drivers do it in userspace.
    
    Code:           Please use the Linux style of code formatting as documented
                    in Documentation/CodingStyle. If you have sections of code
                    that need to be in other formats, for example because they
                    are shared with a windows driver kit and you want to
                    maintain them just once separate them out nicely and note
                    this fact.
    
    Portability:    Pointers are not always 32bits, not all computers are little
                    endian, people do not all have floating point and you
                    shouldn't use inline x86 assembler in your driver without
                    careful thought. Pure x86 drivers generally are not popular.
                    If you only have x86 hardware it is hard to test portability
                    but it is easy to make sure the code can easily be made
                    portable.
    
    Clarity:        It helps if anyone can see how to fix the driver. It helps
                    you because you get patches not bug reports. If you submit a
                    driver that intentionally obfuscates how the hardware works
                    it will go in the bitbucket.
    
    PM support:     Since Linux is used on many portable and desktop systems, your
                    driver is likely to be used on such a system and therefore it
                    should support basic power management by implementing, if
                    necessary, the .suspend and .resume methods used during the
                    system-wide suspend and resume transitions.  You should verify
                    that your driver correctly handles the suspend and resume, but
                    if you are unable to ensure that, please at least define the
                    .suspend method returning the -ENOSYS ("Function not
                    implemented") error.  You should also try to make sure that your
                    driver uses as little power as possible when it's not doing
                    anything.  For the driver testing instructions see
                   Documentation/power/drivers-testing.txt and for a relatively
                   complete overview of the power management issues related to
                   drivers see Documentation/power/devices.txt .
   
   Control:        In general if there is active maintenance of a driver by
                   the author then patches will be redirected to them unless
                   they are totally obvious and without need of checking.
                   If you want to be the contact and update point for the
                   driver it is a good idea to state this in the comments,
                   and include an entry in MAINTAINERS for your driver.
   
   What Criteria Do Not Determine Acceptance
   -----------------------------------------
   
   Vendor:         Being the hardware vendor and maintaining the driver is
                   often a good thing. If there is a stable working driver from
                   other people already in the tree don't expect 'we are the
                   vendor' to get your driver chosen. Ideally work with the
                   existing driver author to build a single perfect driver.
   
   Author:         It doesn't matter if a large Linux company wrote the driver,
                   or you did. Nobody has any special access to the kernel
                   tree. Anyone who tells you otherwise isn't telling the
                   whole story.
   
   
   Resources
   ---------
   
   Linux kernel master tree:
           ftp.??.kernel.org:/pub/linux/kernel/...
           ?? == your country code, such as "us", "uk", "fr", etc.
   
           http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git
   
   Linux kernel mailing list:
           linux-kernel@vger.kernel.org
           [mail majordomo@vger.kernel.org to subscribe]
   
   Linux Device Drivers, Third Edition (covers 2.6.10):
           http://lwn.net/Kernel/LDD3/  (free version)
   
   LWN.net:
           Weekly summary of kernel development activity - http://lwn.net/
           2.6 API changes:
                   http://lwn.net/Articles/2.6-kernel-api/
           Porting drivers from prior kernels to 2.6:
                   http://lwn.net/Articles/driver-porting/
   
   KernelTrap:
           Occasional Linux kernel articles and developer interviews
           http://kerneltrap.org/
   
   KernelNewbies:
           Documentation and assistance for new kernel programmers
           http://kernelnewbies.org/
   
   Linux USB project:
           http://www.linux-usb.org/
   
   How to NOT write kernel driver by Arjan van de Ven:
           http://www.fenrus.org/how-to-not-write-a-device-driver-paper.pdf
   
   Kernel Janitor:
           http://kernelnewbies.org/KernelJanitors
   
   GIT, Fast Version Control System:
           http://git-scm.com/

Cache object: a8a612e4ffd73a356230f0676c841854