1 .. include:: <isonum.txt>
2
3 ============
4 Introduction
5 ============
6
7 :Copyright: |copy| 1999-2001 Vojtech Pavlik <vo
8
9 Architecture
10 ============
11
12 Input subsystem is a collection of drivers tha
13 all input devices under Linux. Most of the dri
14 drivers/input, although quite a few live in dr
15 drivers/platform.
16
17 The core of the input subsystem is the input m
18 loaded before any other of the input modules -
19 communication between two groups of modules:
20
21 Device drivers
22 --------------
23
24 These modules talk to the hardware (for exampl
25 events (keystrokes, mouse movements) to the in
26
27 Event handlers
28 --------------
29
30 These modules get events from input core and p
31 via various interfaces - keystrokes to the ker
32 a simulated PS/2 interface to GPM and X, and s
33
34 Simple Usage
35 ============
36
37 For the most usual configuration, with one USB
38 you'll have to load the following modules (or
39 kernel)::
40
41 input
42 mousedev
43 usbcore
44 uhci_hcd or ohci_hcd or ehci_hcd
45 usbhid
46 hid_generic
47
48 After this, the USB keyboard will work straigh
49 will be available as a character device on maj
50
51 crw-r--r-- 1 root root 13,
52
53 This device is usually created automatically b
54 to create it by hand are::
55
56 cd /dev
57 mkdir input
58 mknod input/mice c 13 63
59
60 After that you have to point GPM (the textmode
61 XFree to this device to use it - GPM should be
62
63 gpm -t ps2 -m /dev/input/mice
64
65 And in X::
66
67 Section "Pointer"
68 Protocol "ImPS/2"
69 Device "/dev/input/mice"
70 ZAxisMapping 4 5
71 EndSection
72
73 When you do all of the above, you can use your
74
75 Detailed Description
76 ====================
77
78 Event handlers
79 --------------
80
81 Event handlers distribute the events from the
82 in-kernel consumers, as needed.
83
84 evdev
85 ~~~~~
86
87 ``evdev`` is the generic input event interface
88 generated in the kernel straight to the progra
89 event codes are the same on all architectures
90 independent.
91
92 This is the preferred interface for userspace
93 input, and all clients are encouraged to use i
94
95 See :ref:`event-interface` for notes on API.
96
97 The devices are in /dev/input::
98
99 crw-r--r-- 1 root root 13,
100 crw-r--r-- 1 root root 13,
101 crw-r--r-- 1 root root 13,
102 crw-r--r-- 1 root root 13,
103 ...
104
105 There are two ranges of minors: 64 through 95
106 range. If there are more than 32 input devices
107 evdev nodes are created with minors starting w
108
109 keyboard
110 ~~~~~~~~
111
112 ``keyboard`` is in-kernel input handler and is
113 consumes keyboard keystrokes and handles user
114
115 mousedev
116 ~~~~~~~~
117
118 ``mousedev`` is a hack to make legacy programs
119 work. It takes events from either mice or digi
120 a PS/2-style (a la /dev/psaux) mouse device av
121 userland.
122
123 Mousedev devices in /dev/input (as shown above
124
125 crw-r--r-- 1 root root 13,
126 crw-r--r-- 1 root root 13,
127 crw-r--r-- 1 root root 13,
128 crw-r--r-- 1 root root 13,
129 ...
130 ...
131 crw-r--r-- 1 root root 13,
132 crw-r--r-- 1 root root 13,
133
134 Each ``mouse`` device is assigned to a single
135 the last one - ``mice``. This single character
136 mice and digitizers, and even if none are conn
137 present. This is useful for hotplugging USB m
138 that do not handle hotplug can open the device
139 present.
140
141 CONFIG_INPUT_MOUSEDEV_SCREEN_[XY] in the kerne
142 the size of your screen (in pixels) in XFree86
143 want to use your digitizer in X, because its m
144 via a virtual PS/2 mouse and thus needs to be
145 accordingly. These values won't be used if you
146
147 Mousedev will generate either PS/2, ImPS/2 (Mi
148 ExplorerPS/2 (IntelliMouse Explorer) protocols
149 program reading the data wishes. You can set G
150 these. You'll need ImPS/2 if you want to make
151 mouse and ExplorerPS/2 if you want to use extr
152
153 joydev
154 ~~~~~~
155
156 ``joydev`` implements v0.x and v1.x Linux joys
157 :ref:`joystick-api` for details.
158
159 As soon as any joystick is connected, it can b
160
161 crw-r--r-- 1 root root 13,
162 crw-r--r-- 1 root root 13,
163 crw-r--r-- 1 root root 13,
164 crw-r--r-- 1 root root 13,
165 ...
166
167 And so on up to js31 in legacy range, and addi
168 above 256 if there are more joystick devices.
169
170 Device drivers
171 --------------
172
173 Device drivers are the modules that generate e
174
175 hid-generic
176 ~~~~~~~~~~~
177
178 ``hid-generic`` is one of the largest and most
179 whole suite. It handles all HID devices, and b
180 wide variety of them, and because the USB HID
181 simple, it needs to be this big.
182
183 Currently, it handles USB mice, joysticks, gam
184 keyboards, trackballs and digitizers.
185
186 However, USB uses HID also for monitor control
187 LCDs and many other purposes.
188
189 The monitor and speaker controls should be eas
190 interface, but for the UPSs and LCDs it doesn'
191 the hiddev interface was designed. See Documen
192 for more information about it.
193
194 The usage of the usbhid module is very simple,
195 detects everything automatically and when a HI
196 detects it appropriately.
197
198 However, because the devices vary wildly, you
199 device that doesn't work well. In that case #d
200 of hid-core.c and send me the syslog traces.
201
202 usbmouse
203 ~~~~~~~~
204
205 For embedded systems, for mice with broken HID
206 other use when the big usbhid wouldn't be a go
207 usbmouse driver. It handles USB mice only. It
208 protocol. This also means the mice must suppor
209 all do. If you don't have any strong reason to
210 instead.
211
212 usbkbd
213 ~~~~~~
214
215 Much like usbmouse, this module talks to keybo
216 HIDBP protocol. It's smaller, but doesn't supp
217 Use usbhid instead if there isn't any special
218
219 psmouse
220 ~~~~~~~
221
222 This is driver for all flavors of pointing dev
223 protocol, including Synaptics and ALPS touchpa
224 Explorer devices, Logitech PS/2 mice and so on
225
226 atkbd
227 ~~~~~
228
229 This is driver for PS/2 (AT) keyboards.
230
231 iforce
232 ~~~~~~
233
234 A driver for I-Force joysticks and wheels, bot
235 It includes Force Feedback support now, even t
236 Corp. considers the protocol a trade secret an
237 about it.
238
239 Verifying if it works
240 =====================
241
242 Typing a couple keys on the keyboard should be
243 a keyboard works and is correctly connected to
244 driver.
245
246 Doing a ``cat /dev/input/mouse0`` (c, 13, 32)
247 is also emulated; characters should appear if
248
249 You can test the joystick emulation with the `
250 available in the joystick package (see :ref:`j
251
252 You can test the event devices with the ``evte
253
254 .. _event-interface:
255
256 Event interface
257 ===============
258
259 You can use blocking and nonblocking reads, an
260 /dev/input/eventX devices, and you'll always g
261 events on a read. Their layout is::
262
263 struct input_event {
264 struct timeval time;
265 unsigned short type;
266 unsigned short code;
267 unsigned int value;
268 };
269
270 ``time`` is the timestamp, it returns the time
271 Type is for example EV_REL for relative moveme
272 release. More types are defined in include/uap
273
274 ``code`` is event code, for example REL_X or K
275 list is in include/uapi/linux/input-event-code
276
277 ``value`` is the value the event carries. Eith
278 EV_REL, absolute new value for EV_ABS (joystic
279 release, 1 for keypress and 2 for autorepeat.
280
281 See :ref:`input-event-codes` for more informat
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