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