diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/input/input.txt |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
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1 | Linux Input drivers v1.0 | ||
2 | (c) 1999-2001 Vojtech Pavlik <vojtech@ucw.cz> | ||
3 | Sponsored by SuSE | ||
4 | $Id: input.txt,v 1.8 2002/05/29 03:15:01 bradleym Exp $ | ||
5 | ---------------------------------------------------------------------------- | ||
6 | |||
7 | 0. Disclaimer | ||
8 | ~~~~~~~~~~~~~ | ||
9 | This program is free software; you can redistribute it and/or modify it | ||
10 | under the terms of the GNU General Public License as published by the Free | ||
11 | Software Foundation; either version 2 of the License, or (at your option) | ||
12 | any later version. | ||
13 | |||
14 | This program is distributed in the hope that it will be useful, but | ||
15 | WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY | ||
16 | or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | ||
17 | more details. | ||
18 | |||
19 | You should have received a copy of the GNU General Public License along | ||
20 | with this program; if not, write to the Free Software Foundation, Inc., 59 | ||
21 | Temple Place, Suite 330, Boston, MA 02111-1307 USA | ||
22 | |||
23 | Should you need to contact me, the author, you can do so either by e-mail | ||
24 | - mail your message to <vojtech@ucw.cz>, or by paper mail: Vojtech Pavlik, | ||
25 | Simunkova 1594, Prague 8, 182 00 Czech Republic | ||
26 | |||
27 | For your convenience, the GNU General Public License version 2 is included | ||
28 | in the package: See the file COPYING. | ||
29 | |||
30 | 1. Introduction | ||
31 | ~~~~~~~~~~~~~~~ | ||
32 | This is a collection of drivers that is designed to support all input | ||
33 | devices under Linux. While it is currently used only on for USB input | ||
34 | devices, future use (say 2.5/2.6) is expected to expand to replace | ||
35 | most of the existing input system, which is why it lives in | ||
36 | drivers/input/ instead of drivers/usb/. | ||
37 | |||
38 | The centre of the input drivers is the input module, which must be | ||
39 | loaded before any other of the input modules - it serves as a way of | ||
40 | communication between two groups of modules: | ||
41 | |||
42 | 1.1 Device drivers | ||
43 | ~~~~~~~~~~~~~~~~~~ | ||
44 | These modules talk to the hardware (for example via USB), and provide | ||
45 | events (keystrokes, mouse movements) to the input module. | ||
46 | |||
47 | 1.2 Event handlers | ||
48 | ~~~~~~~~~~~~~~~~~~ | ||
49 | These modules get events from input and pass them where needed via | ||
50 | various interfaces - keystrokes to the kernel, mouse movements via a | ||
51 | simulated PS/2 interface to GPM and X and so on. | ||
52 | |||
53 | 2. Simple Usage | ||
54 | ~~~~~~~~~~~~~~~ | ||
55 | For the most usual configuration, with one USB mouse and one USB keyboard, | ||
56 | you'll have to load the following modules (or have them built in to the | ||
57 | kernel): | ||
58 | |||
59 | input | ||
60 | mousedev | ||
61 | keybdev | ||
62 | usbcore | ||
63 | uhci_hcd or ohci_hcd or ehci_hcd | ||
64 | usbhid | ||
65 | |||
66 | After this, the USB keyboard will work straight away, and the USB mouse | ||
67 | will be available as a character device on major 13, minor 63: | ||
68 | |||
69 | crw-r--r-- 1 root root 13, 63 Mar 28 22:45 mice | ||
70 | |||
71 | This device has to be created, unless you use devfs, in which case it's | ||
72 | created automatically. The commands to do create it by hand are: | ||
73 | |||
74 | cd /dev | ||
75 | mkdir input | ||
76 | mknod input/mice c 13 63 | ||
77 | |||
78 | After that you have to point GPM (the textmode mouse cut&paste tool) and | ||
79 | XFree to this device to use it - GPM should be called like: | ||
80 | |||
81 | gpm -t ps2 -m /dev/input/mice | ||
82 | |||
83 | And in X: | ||
84 | |||
85 | Section "Pointer" | ||
86 | Protocol "ImPS/2" | ||
87 | Device "/dev/input/mice" | ||
88 | ZAxisMapping 4 5 | ||
89 | EndSection | ||
90 | |||
91 | When you do all of the above, you can use your USB mouse and keyboard. | ||
92 | |||
93 | 3. Detailed Description | ||
94 | ~~~~~~~~~~~~~~~~~~~~~~~ | ||
95 | 3.1 Device drivers | ||
96 | ~~~~~~~~~~~~~~~~~~ | ||
97 | Device drivers are the modules that generate events. The events are | ||
98 | however not useful without being handled, so you also will need to use some | ||
99 | of the modules from section 3.2. | ||
100 | |||
101 | 3.1.1 usbhid | ||
102 | ~~~~~~~~~~~~ | ||
103 | usbhid is the largest and most complex driver of the whole suite. It | ||
104 | handles all HID devices, and because there is a very wide variety of them, | ||
105 | and because the USB HID specification isn't simple, it needs to be this big. | ||
106 | |||
107 | Currently, it handles USB mice, joysticks, gamepads, steering wheels | ||
108 | keyboards, trackballs and digitizers. | ||
109 | |||
110 | However, USB uses HID also for monitor controls, speaker controls, UPSs, | ||
111 | LCDs and many other purposes. | ||
112 | |||
113 | The monitor and speaker controls should be easy to add to the hid/input | ||
114 | interface, but for the UPSs and LCDs it doesn't make much sense. For this, | ||
115 | the hiddev interface was designed. See Documentation/usb/hiddev.txt | ||
116 | for more information about it. | ||
117 | |||
118 | The usage of the usbhid module is very simple, it takes no parameters, | ||
119 | detects everything automatically and when a HID device is inserted, it | ||
120 | detects it appropriately. | ||
121 | |||
122 | However, because the devices vary wildly, you might happen to have a | ||
123 | device that doesn't work well. In that case #define DEBUG at the beginning | ||
124 | of hid-core.c and send me the syslog traces. | ||
125 | |||
126 | 3.1.2 usbmouse | ||
127 | ~~~~~~~~~~~~~~ | ||
128 | For embedded systems, for mice with broken HID descriptors and just any | ||
129 | other use when the big usbhid wouldn't be a good choice, there is the | ||
130 | usbmouse driver. It handles USB mice only. It uses a simpler HIDBP | ||
131 | protocol. This also means the mice must support this simpler protocol. Not | ||
132 | all do. If you don't have any strong reason to use this module, use usbhid | ||
133 | instead. | ||
134 | |||
135 | 3.1.3 usbkbd | ||
136 | ~~~~~~~~~~~~ | ||
137 | Much like usbmouse, this module talks to keyboards with a simplified | ||
138 | HIDBP protocol. It's smaller, but doesn't support any extra special keys. | ||
139 | Use usbhid instead if there isn't any special reason to use this. | ||
140 | |||
141 | 3.1.4 wacom | ||
142 | ~~~~~~~~~~~ | ||
143 | This is a driver for Wacom Graphire and Intuos tablets. Not for Wacom | ||
144 | PenPartner, that one is handled by the HID driver. Although the Intuos and | ||
145 | Graphire tablets claim that they are HID tablets as well, they are not and | ||
146 | thus need this specific driver. | ||
147 | |||
148 | 3.1.5 iforce | ||
149 | ~~~~~~~~~~~~ | ||
150 | A driver for I-Force joysticks and wheels, both over USB and RS232. | ||
151 | It includes ForceFeedback support now, even though Immersion | ||
152 | Corp. considers the protocol a trade secret and won't disclose a word | ||
153 | about it. | ||
154 | |||
155 | 3.2 Event handlers | ||
156 | ~~~~~~~~~~~~~~~~~~ | ||
157 | Event handlers distrubite the events from the devices to userland and | ||
158 | kernel, as needed. | ||
159 | |||
160 | 3.2.1 keybdev | ||
161 | ~~~~~~~~~~~~~ | ||
162 | keybdev is currently a rather ugly hack that translates the input | ||
163 | events into architecture-specific keyboard raw mode (Xlated AT Set2 on | ||
164 | x86), and passes them into the handle_scancode function of the | ||
165 | keyboard.c module. This works well enough on all architectures that | ||
166 | keybdev can generate rawmode on, other architectures can be added to | ||
167 | it. | ||
168 | |||
169 | The right way would be to pass the events to keyboard.c directly, | ||
170 | best if keyboard.c would itself be an event handler. This is done in | ||
171 | the input patch, available on the webpage mentioned below. | ||
172 | |||
173 | 3.2.2 mousedev | ||
174 | ~~~~~~~~~~~~~~ | ||
175 | mousedev is also a hack to make programs that use mouse input | ||
176 | work. It takes events from either mice or digitizers/tablets and makes | ||
177 | a PS/2-style (a la /dev/psaux) mouse device available to the | ||
178 | userland. Ideally, the programs could use a more reasonable interface, | ||
179 | for example evdev | ||
180 | |||
181 | Mousedev devices in /dev/input (as shown above) are: | ||
182 | |||
183 | crw-r--r-- 1 root root 13, 32 Mar 28 22:45 mouse0 | ||
184 | crw-r--r-- 1 root root 13, 33 Mar 29 00:41 mouse1 | ||
185 | crw-r--r-- 1 root root 13, 34 Mar 29 00:41 mouse2 | ||
186 | crw-r--r-- 1 root root 13, 35 Apr 1 10:50 mouse3 | ||
187 | ... | ||
188 | ... | ||
189 | crw-r--r-- 1 root root 13, 62 Apr 1 10:50 mouse30 | ||
190 | crw-r--r-- 1 root root 13, 63 Apr 1 10:50 mice | ||
191 | |||
192 | Each 'mouse' device is assigned to a single mouse or digitizer, except | ||
193 | the last one - 'mice'. This single character device is shared by all | ||
194 | mice and digitizers, and even if none are connected, the device is | ||
195 | present. This is useful for hotplugging USB mice, so that programs | ||
196 | can open the device even when no mice are present. | ||
197 | |||
198 | CONFIG_INPUT_MOUSEDEV_SCREEN_[XY] in the kernel configuration are | ||
199 | the size of your screen (in pixels) in XFree86. This is needed if you | ||
200 | want to use your digitizer in X, because its movement is sent to X | ||
201 | via a virtual PS/2 mouse and thus needs to be scaled | ||
202 | accordingly. These values won't be used if you use a mouse only. | ||
203 | |||
204 | Mousedev will generate either PS/2, ImPS/2 (Microsoft IntelliMouse) or | ||
205 | ExplorerPS/2 (IntelliMouse Explorer) protocols, depending on what the | ||
206 | program reading the data wishes. You can set GPM and X to any of | ||
207 | these. You'll need ImPS/2 if you want to make use of a wheel on a USB | ||
208 | mouse and ExplorerPS/2 if you want to use extra (up to 5) buttons. | ||
209 | |||
210 | 3.2.3 joydev | ||
211 | ~~~~~~~~~~~~ | ||
212 | Joydev implements v0.x and v1.x Linux joystick api, much like | ||
213 | drivers/char/joystick/joystick.c used to in earlier versions. See | ||
214 | joystick-api.txt in the Documentation subdirectory for details. As | ||
215 | soon as any joystick is connected, it can be accessed in /dev/input | ||
216 | on: | ||
217 | |||
218 | crw-r--r-- 1 root root 13, 0 Apr 1 10:50 js0 | ||
219 | crw-r--r-- 1 root root 13, 1 Apr 1 10:50 js1 | ||
220 | crw-r--r-- 1 root root 13, 2 Apr 1 10:50 js2 | ||
221 | crw-r--r-- 1 root root 13, 3 Apr 1 10:50 js3 | ||
222 | ... | ||
223 | |||
224 | And so on up to js31. | ||
225 | |||
226 | 3.2.4 evdev | ||
227 | ~~~~~~~~~~~ | ||
228 | evdev is the generic input event interface. It passes the events | ||
229 | generated in the kernel straight to the program, with timestamps. The | ||
230 | API is still evolving, but should be useable now. It's described in | ||
231 | section 5. | ||
232 | |||
233 | This should be the way for GPM and X to get keyboard and mouse mouse | ||
234 | events. It allows for multihead in X without any specific multihead | ||
235 | kernel support. The event codes are the same on all architectures and | ||
236 | are hardware independent. | ||
237 | |||
238 | The devices are in /dev/input: | ||
239 | |||
240 | crw-r--r-- 1 root root 13, 64 Apr 1 10:49 event0 | ||
241 | crw-r--r-- 1 root root 13, 65 Apr 1 10:50 event1 | ||
242 | crw-r--r-- 1 root root 13, 66 Apr 1 10:50 event2 | ||
243 | crw-r--r-- 1 root root 13, 67 Apr 1 10:50 event3 | ||
244 | ... | ||
245 | |||
246 | And so on up to event31. | ||
247 | |||
248 | 4. Verifying if it works | ||
249 | ~~~~~~~~~~~~~~~~~~~~~~~~ | ||
250 | Typing a couple keys on the keyboard should be enough to check that | ||
251 | a USB keyboard works and is correctly connected to the kernel keyboard | ||
252 | driver. | ||
253 | |||
254 | Doing a cat /dev/input/mouse0 (c, 13, 32) will verify that a mouse | ||
255 | is also emulated, characters should appear if you move it. | ||
256 | |||
257 | You can test the joystick emulation with the 'jstest' utility, | ||
258 | available in the joystick package (see Documentation/input/joystick.txt). | ||
259 | |||
260 | You can test the event devices with the 'evtest' utility available | ||
261 | in the LinuxConsole project CVS archive (see the URL below). | ||
262 | |||
263 | 5. Event interface | ||
264 | ~~~~~~~~~~~~~~~~~~ | ||
265 | Should you want to add event device support into any application (X, gpm, | ||
266 | svgalib ...) I <vojtech@ucw.cz> will be happy to provide you any help I | ||
267 | can. Here goes a description of the current state of things, which is going | ||
268 | to be extended, but not changed incompatibly as time goes: | ||
269 | |||
270 | You can use blocking and nonblocking reads, also select() on the | ||
271 | /dev/input/eventX devices, and you'll always get a whole number of input | ||
272 | events on a read. Their layout is: | ||
273 | |||
274 | struct input_event { | ||
275 | struct timeval time; | ||
276 | unsigned short type; | ||
277 | unsigned short code; | ||
278 | unsigned int value; | ||
279 | }; | ||
280 | |||
281 | 'time' is the timestamp, it returns the time at which the event happened. | ||
282 | Type is for example EV_REL for relative momement, REL_KEY for a keypress or | ||
283 | release. More types are defined in include/linux/input.h. | ||
284 | |||
285 | 'code' is event code, for example REL_X or KEY_BACKSPACE, again a complete | ||
286 | list is in include/linux/input.h. | ||
287 | |||
288 | 'value' is the value the event carries. Either a relative change for | ||
289 | EV_REL, absolute new value for EV_ABS (joysticks ...), or 0 for EV_KEY for | ||
290 | release, 1 for keypress and 2 for autorepeat. | ||
291 | |||
292 | 6. Contacts | ||
293 | ~~~~~~~~~~~ | ||
294 | This effort has its home page at: | ||
295 | |||
296 | http://www.suse.cz/development/input/ | ||
297 | |||
298 | You'll find both the latest HID driver and the complete Input driver | ||
299 | there as well as information how to access the CVS repository for | ||
300 | latest revisions of the drivers. | ||
301 | |||
302 | There is also a mailing list for this: | ||
303 | |||
304 | majordomo@atrey.karlin.mff.cuni.cz | ||
305 | |||
306 | Send "subscribe linux-input" to subscribe to it. | ||
307 | |||
308 | The input changes are also being worked on as part of the LinuxConsole | ||
309 | project, see: | ||
310 | |||
311 | http://sourceforge.net/projects/linuxconsole/ | ||
312 | |||