1 Linux Input drivers v1.0
2 (c) 1999-2001 Vojtech Pavlik <vojtech@suse.cz>
4 $Id: input.txt,v 1.5 2001/06/06 11:05:33 vojtech Exp $
5 ----------------------------------------------------------------------------
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)
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
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
23 Should you need to contact me, the author, you can do so either by e-mail
24 - mail your message to <vojtech@suse.cz>, or by paper mail: Vojtech Pavlik,
25 Simunkova 1594, Prague 8, 182 00 Czech Republic
27 For your convenience, the GNU General Public License version 2 is included
28 in the package: See the file COPYING.
32 This is a collection of drivers that is designed to support all input
33 devices under Linux. However, in the current kernels, although it's
34 possibilities are much bigger, it's limited to USB devices only. This is
35 also why it resides in the drivers/usb subdirectory.
37 The center of the input drivers is the input.o module, which must be
38 loaded before any other of the input modules - it serves as a way of
39 communication between two groups of modules:
43 These modules talk to the hardware (for example via USB), and provide
44 events (keystrokes, mouse movements) to the input.o module.
48 These modules get events from input.o and pass them where needed via
49 various interfaces - keystrokes to the kernel, mouse movements via a
50 simulated PS/2 interface to GPM and X and so on.
54 For the most usual configuration, with one USB mouse and one USB keyboard,
55 you'll have to load the following modules (or have them built in to the
65 After this, the USB keyboard will work straight away, and the USB mouse
66 will be available as a character device on major 13, minor 63:
68 crw-r--r-- 1 root root 13, 63 Mar 28 22:45 mice
70 This device, has to be created, unless you use devfs, in which case it's
71 created automatically. The commands to do that are:
75 mknod input/mice c 13 63
77 After that you have to point GPM (the textmode mouse cut&paste tool) and
78 XFree to this device to use it - GPM should be called like:
80 gpm -t ps2 -m /dev/input/mice
86 Device "/dev/input/mice"
90 When you do all of the above, you can use your USB mouse and keyboard.
92 3. Detailed Description
93 ~~~~~~~~~~~~~~~~~~~~~~~
96 Device drivers are the modules that generate events. The events are
97 however not useful without being handled, so you also will need to use some
98 of the modules from section 3.2.
102 Hid.c is the largest and most complex driver of the whole suite. It
103 handles all HID devices, and because there is a very wide variety of them,
104 and because the USB HID specification isn't simple, it needs to be this big.
106 Currently, it handles USB mice, joysticks, gamepads, steering wheels
107 keyboards, trackballs and digitizers.
109 However, USB uses HID also for monitor controls, speaker controls, UPSs,
110 LCDs and many other purposes.
112 The monitor and speaker controls should be easy to add to the hid/input
113 interface, but for the UPSs and LCDs it doesn't make much sense. For this,
114 the hiddev interface was designed. See Documentation/usb/hiddev.txt
115 for more information about it.
117 The usage of the hid.o module is very simple, it takes no parameters,
118 detects everything automatically and when a HID device is inserted, it
119 detects it appropriately.
121 However, because the devices vary wildly, you might happen to have a
122 device that doesn't work well. In that case #define DEBUG at the beginning
123 of hid.c and send me the syslog traces.
127 For embedded systems, for mice with broken HID descriptors and just any
128 other use when the big hid.c wouldn't be a good choice, there is the
129 usbmouse.c driver. It handles USB mice only. It uses a simpler HIDBP
130 protocol. This also means the mice must support this simpler protocol. Not
131 all do. If you don't have any strong reason to use this module, use hid.c
136 Much like usbmouse.c, this module talks to keyboards with a simpplified
137 HIDBP protocol. It's smaller, but doesn't support any extra special keys.
138 Use hid.c instead if there isn't any special reason to use this.
142 This is a driver for Wacom Graphire and Intuos tablets. Not for Wacom
143 PenPartner, that one is handled by the HID driver. Although the Intuos and
144 Graphire tablets claim that they are HID tablets as well, they are not and
145 thus need this specific driver.
149 A driver for I-Force joysticks and wheels, both over USB and RS232.
150 It includes ForceFeedback support now, even though Immersion Corp. considers
151 the protocol a trade secret and won't disclose a word about it.
155 Event handlers distrubite the events from the devices to userland and
160 Keybdev is currently a rather ugly hack that translates the input events
161 into architecture-specific keyboard raw mode (Xlated AT Set2 on x86), and
162 passes them into the handle_scancode function of the keyboard.c module. This
163 works well enough on all architectures that keybdev can generate rawmode on,
164 other architectures can be added to it.
166 The right way would be to pass the events to keyboard.c directly, best if
167 keyboard.c would itself be an event handler. This is done in the input
168 patch, available on the webpage mentioned below.
172 Mousedev is also a hack to make programs that use mouse input work. It
173 takes events from either mice or digitizers/tablets and makes a PS/2-style
174 (a la /dev/psaux) mouse device available to the userland. Ideally, the
175 programs could use a more reasonable interface, for example evdev.c
177 Mousedev devices in /dev/input (as shown above) are:
179 crw-r--r-- 1 root root 13, 32 Mar 28 22:45 mouse0
180 crw-r--r-- 1 root root 13, 33 Mar 29 00:41 mouse1
181 crw-r--r-- 1 root root 13, 34 Mar 29 00:41 mouse2
182 crw-r--r-- 1 root root 13, 35 Apr 1 10:50 mouse3
185 crw-r--r-- 1 root root 13, 62 Apr 1 10:50 mouse30
186 crw-r--r-- 1 root root 13, 63 Apr 1 10:50 mice
188 Each 'mouse' device is assigned to a single mouse or digitizer, except the last
189 one - 'mice'. This single character device is shared by all mice and
190 digitizers, and even if none are connected, the device is present. This is
191 useful for hotplugging USB mice, so that programs can open the device even when
194 CONFIG_INPUT_MOUSEDEV_SCREEN_[XY] in the kernel configuration are the size
195 of your screen (in pixels) in XFree86. This is needed if you want to use
196 your digitizer in X, because it's movement is sent to X via a virtual PS/2
197 mouse and thus needs to be scaled accordingly. These values won't be used if
198 you use a mouse only.
200 Mousedev will generate either PS/2, ImPS/2 (Microsoft IntelliMouse) or
201 ExplorerPS/2 (IntelliMouse Explorer) protocols, depending on what the program
202 reading the data wishes. You can set GPM and X to any of these. You'll need
203 ImPS/2 if you want to make use of a wheel on a USB mouse and ExplorerPS/2 if you
204 want to use extra (up to 5) buttons.
208 Joydev implements v0.x and v1.x Linux joystick api, much like
209 drivers/char/joystick/joystick.c used to in earlier versions. See
210 joystick-api.txt in the Documentation subdirectory for details. As soon as
211 any joystick is connected, it can be accessed in /dev/input on:
213 crw-r--r-- 1 root root 13, 0 Apr 1 10:50 js0
214 crw-r--r-- 1 root root 13, 1 Apr 1 10:50 js1
215 crw-r--r-- 1 root root 13, 2 Apr 1 10:50 js2
216 crw-r--r-- 1 root root 13, 3 Apr 1 10:50 js3
219 And so on up to js31.
223 Evdev is the generic input event interface. It passes the events generated
224 in the kernel straight to the program, with timestamps. The API is still
225 evolving, but should be useable now. It's described in section 5.
227 This should be the way for GPM and X to get keyboard and mouse mouse
228 events. It allows for multihead in X without any specific multihead kernel
229 support. The event codes are the same on all architectures and are hardware
232 The devices are in /dev/input:
234 crw-r--r-- 1 root root 13, 64 Apr 1 10:49 event0
235 crw-r--r-- 1 root root 13, 65 Apr 1 10:50 event1
236 crw-r--r-- 1 root root 13, 66 Apr 1 10:50 event2
237 crw-r--r-- 1 root root 13, 67 Apr 1 10:50 event3
242 This effort has it's home page at:
244 http://www.suse.cz/development/input/
246 You'll find both the latest HID driver and the complete Input driver there
247 as well as information how to access the CVS repository for latest revisions
250 There is also a mailing list for this:
252 majordomo@atrey.karlin.mff.cuni.cz
254 Send "subscribe linux-input" to subscribe to it.
256 4. Verifying if it works
257 ~~~~~~~~~~~~~~~~~~~~~~~~
258 Typing a couple keys on the keyboard should be enough to check that a USB
259 keyboard works and is correctly connected to the kernel keyboard driver.
261 Doing a cat /dev/input/mouse0 (c, 13, 32) will verify that a mouse is also
262 emulated, characters should appear if you move it.
264 You can test the joystick emulation with the 'jstest' utility, available
265 in the joystick package (see Documentation/joystick.txt).
267 You can test the event devics with the 'evtest' utitily available on the
268 input driver homepage (see the URL above).
272 Should you want to add event device support into any application (X, gpm,
273 svgalib ...) I <vojtech@suse.cz> will be happy to provide you any help I
274 can. Here goes a description of the current state of things, which is going
275 to be extended, but not changed incompatibly as time goes:
277 You can use blocking and nonblocking reads, also select() on the
278 /dev/input/eventX devices, and you'll always get a whole number of input
279 events on a read. Their layout is:
288 'time' is the timestamp, it returns the time at which the event happened.
289 Type is for example EV_REL for relative momement, REL_KEY for a keypress or
290 release. More types are defined in include/linux/input.h.
292 'code' is event code, for example REL_X or KEY_BACKSPACE, again a complete
293 list is in include/linux/input.h.
295 'value' is the value the event carries. Either a relative change for
296 EV_REL, absolute new value for EV_ABS (joysticks ...), or 0 for EV_KEY for
297 release, 1 for keypress and 2 for autorepeat.