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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 | |
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16 | by the Linux assigned name and number authority (currently this is |
17 | Torben Mathiasen). The site is http://www.lanana.org/. This | |
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18 | also deals with allocating numbers for devices that are not going to |
19 | be submitted to the mainstream kernel. | |
84da7c08 | 20 | See Documentation/devices.txt for more information on this. |
1da177e4 | 21 | |
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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 | |
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24 | have shipped to customers before. |
25 | ||
26 | Who To Submit Drivers To | |
27 | ------------------------ | |
28 | ||
29 | Linux 2.0: | |
5b0ed2c6 | 30 | No new drivers are accepted for this kernel tree. |
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31 | |
32 | Linux 2.2: | |
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33 | No new drivers are accepted for this kernel tree. |
34 | ||
35 | Linux 2.4: | |
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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 | |
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39 | maintainer then please contact Marcelo Tosatti |
40 | <marcelo.tosatti@cyclades.com>. | |
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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 | |
84da7c08 | 52 | of exclusive GPL licensing, and if you wish the driver |
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53 | to be useful to other communities such as BSD you may well |
54 | wish to release under multiple licenses. | |
5b0ed2c6 | 55 | See accepted licenses at include/linux/module.h |
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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 | |
3706baa8 | 62 | the copyright owner. |
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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 | |
3706baa8 | 66 | to be accepted than if it invents gratuitous new ones. |
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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 | ||
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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 | ||
1da177e4 | 105 | Control: In general if there is active maintainance of a driver by |
3706baa8 | 106 | the author then patches will be redirected to them unless |
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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 | |
3706baa8 | 118 | vendor' to get your driver chosen. Ideally work with the |
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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 | ||
3706baa8 | 134 | Linux kernel mailing list: |
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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 | ||
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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: | |
e1b114ee | 157 | http://www.linux-usb.org/ |
5b0ed2c6 | 158 | |
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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 | |
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161 | |
162 | Kernel Janitor: | |
163 | http://janitor.kernelnewbies.org/ |