diff options
author | Mauro Carvalho Chehab <mchehab@s-opensource.com> | 2017-04-04 20:44:04 -0400 |
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committer | Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2017-04-05 18:44:56 -0400 |
commit | 1c4ada609d6a0b9ddd4621cef6ac57790289ff4f (patch) | |
tree | 7eb22fd2d6d46bb6c74548dcdf5afd171d84361c /Documentation/input | |
parent | f863995224da8e63e8703ca9eb0b2e29d93f5d66 (diff) |
Input: convert input-programming doc into ReST format
This file require minimum adjustments to be a valid ReST file.
Do it, in order to be able to parse it with Sphinx.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Diffstat (limited to 'Documentation/input')
-rw-r--r-- | Documentation/input/input-programming.txt | 265 |
1 files changed, 134 insertions, 131 deletions
diff --git a/Documentation/input/input-programming.txt b/Documentation/input/input-programming.txt index 7f8b9d97bc47..4d3b22222e93 100644 --- a/Documentation/input/input-programming.txt +++ b/Documentation/input/input-programming.txt | |||
@@ -1,77 +1,78 @@ | |||
1 | ~~~~~~~~~~~~~~~~~~~~~~~~~ | ||
1 | Programming input drivers | 2 | Programming input drivers |
2 | ~~~~~~~~~~~~~~~~~~~~~~~~~ | 3 | ~~~~~~~~~~~~~~~~~~~~~~~~~ |
3 | 4 | ||
4 | 1. Creating an input device driver | 5 | Creating an input device driver |
5 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | 6 | =============================== |
6 | 7 | ||
7 | 1.0 The simplest example | 8 | The simplest example |
8 | ~~~~~~~~~~~~~~~~~~~~~~~~ | 9 | ~~~~~~~~~~~~~~~~~~~~ |
9 | 10 | ||
10 | Here comes a very simple example of an input device driver. The device has | 11 | Here comes a very simple example of an input device driver. The device has |
11 | just one button and the button is accessible at i/o port BUTTON_PORT. When | 12 | just one button and the button is accessible at i/o port BUTTON_PORT. When |
12 | pressed or released a BUTTON_IRQ happens. The driver could look like: | 13 | pressed or released a BUTTON_IRQ happens. The driver could look like:: |
13 | 14 | ||
14 | #include <linux/input.h> | 15 | #include <linux/input.h> |
15 | #include <linux/module.h> | 16 | #include <linux/module.h> |
16 | #include <linux/init.h> | 17 | #include <linux/init.h> |
17 | 18 | ||
18 | #include <asm/irq.h> | 19 | #include <asm/irq.h> |
19 | #include <asm/io.h> | 20 | #include <asm/io.h> |
20 | 21 | ||
21 | static struct input_dev *button_dev; | 22 | static struct input_dev *button_dev; |
22 | 23 | ||
23 | static irqreturn_t button_interrupt(int irq, void *dummy) | 24 | static irqreturn_t button_interrupt(int irq, void *dummy) |
24 | { | 25 | { |
25 | input_report_key(button_dev, BTN_0, inb(BUTTON_PORT) & 1); | 26 | input_report_key(button_dev, BTN_0, inb(BUTTON_PORT) & 1); |
26 | input_sync(button_dev); | 27 | input_sync(button_dev); |
27 | return IRQ_HANDLED; | 28 | return IRQ_HANDLED; |
28 | } | 29 | } |
29 | 30 | ||
30 | static int __init button_init(void) | 31 | static int __init button_init(void) |
31 | { | 32 | { |
32 | int error; | 33 | int error; |
33 | 34 | ||
34 | if (request_irq(BUTTON_IRQ, button_interrupt, 0, "button", NULL)) { | 35 | if (request_irq(BUTTON_IRQ, button_interrupt, 0, "button", NULL)) { |
35 | printk(KERN_ERR "button.c: Can't allocate irq %d\n", button_irq); | 36 | printk(KERN_ERR "button.c: Can't allocate irq %d\n", button_irq); |
36 | return -EBUSY; | 37 | return -EBUSY; |
37 | } | 38 | } |
38 | 39 | ||
39 | button_dev = input_allocate_device(); | 40 | button_dev = input_allocate_device(); |
40 | if (!button_dev) { | 41 | if (!button_dev) { |
41 | printk(KERN_ERR "button.c: Not enough memory\n"); | 42 | printk(KERN_ERR "button.c: Not enough memory\n"); |
42 | error = -ENOMEM; | 43 | error = -ENOMEM; |
43 | goto err_free_irq; | 44 | goto err_free_irq; |
44 | } | 45 | } |
45 | 46 | ||
46 | button_dev->evbit[0] = BIT_MASK(EV_KEY); | 47 | button_dev->evbit[0] = BIT_MASK(EV_KEY); |
47 | button_dev->keybit[BIT_WORD(BTN_0)] = BIT_MASK(BTN_0); | 48 | button_dev->keybit[BIT_WORD(BTN_0)] = BIT_MASK(BTN_0); |
48 | 49 | ||
49 | error = input_register_device(button_dev); | 50 | error = input_register_device(button_dev); |
50 | if (error) { | 51 | if (error) { |
51 | printk(KERN_ERR "button.c: Failed to register device\n"); | 52 | printk(KERN_ERR "button.c: Failed to register device\n"); |
52 | goto err_free_dev; | 53 | goto err_free_dev; |
53 | } | 54 | } |
54 | 55 | ||
55 | return 0; | 56 | return 0; |
56 | 57 | ||
57 | err_free_dev: | 58 | err_free_dev: |
58 | input_free_device(button_dev); | 59 | input_free_device(button_dev); |
59 | err_free_irq: | 60 | err_free_irq: |
60 | free_irq(BUTTON_IRQ, button_interrupt); | 61 | free_irq(BUTTON_IRQ, button_interrupt); |
61 | return error; | 62 | return error; |
62 | } | 63 | } |
63 | 64 | ||
64 | static void __exit button_exit(void) | 65 | static void __exit button_exit(void) |
65 | { | 66 | { |
66 | input_unregister_device(button_dev); | 67 | input_unregister_device(button_dev); |
67 | free_irq(BUTTON_IRQ, button_interrupt); | 68 | free_irq(BUTTON_IRQ, button_interrupt); |
68 | } | 69 | } |
69 | 70 | ||
70 | module_init(button_init); | 71 | module_init(button_init); |
71 | module_exit(button_exit); | 72 | module_exit(button_exit); |
72 | 73 | ||
73 | 1.1 What the example does | 74 | What the example does |
74 | ~~~~~~~~~~~~~~~~~~~~~~~~~ | 75 | ~~~~~~~~~~~~~~~~~~~~~ |
75 | 76 | ||
76 | First it has to include the <linux/input.h> file, which interfaces to the | 77 | First it has to include the <linux/input.h> file, which interfaces to the |
77 | input subsystem. This provides all the definitions needed. | 78 | input subsystem. This provides all the definitions needed. |
@@ -85,7 +86,7 @@ and sets up input bitfields. This way the device driver tells the other | |||
85 | parts of the input systems what it is - what events can be generated or | 86 | parts of the input systems what it is - what events can be generated or |
86 | accepted by this input device. Our example device can only generate EV_KEY | 87 | accepted by this input device. Our example device can only generate EV_KEY |
87 | type events, and from those only BTN_0 event code. Thus we only set these | 88 | type events, and from those only BTN_0 event code. Thus we only set these |
88 | two bits. We could have used | 89 | two bits. We could have used:: |
89 | 90 | ||
90 | set_bit(EV_KEY, button_dev.evbit); | 91 | set_bit(EV_KEY, button_dev.evbit); |
91 | set_bit(BTN_0, button_dev.keybit); | 92 | set_bit(BTN_0, button_dev.keybit); |
@@ -93,7 +94,7 @@ two bits. We could have used | |||
93 | as well, but with more than single bits the first approach tends to be | 94 | as well, but with more than single bits the first approach tends to be |
94 | shorter. | 95 | shorter. |
95 | 96 | ||
96 | Then the example driver registers the input device structure by calling | 97 | Then the example driver registers the input device structure by calling:: |
97 | 98 | ||
98 | input_register_device(&button_dev); | 99 | input_register_device(&button_dev); |
99 | 100 | ||
@@ -102,12 +103,12 @@ calls device handler modules _connect functions to tell them a new input | |||
102 | device has appeared. input_register_device() may sleep and therefore must | 103 | device has appeared. input_register_device() may sleep and therefore must |
103 | not be called from an interrupt or with a spinlock held. | 104 | not be called from an interrupt or with a spinlock held. |
104 | 105 | ||
105 | While in use, the only used function of the driver is | 106 | While in use, the only used function of the driver is:: |
106 | 107 | ||
107 | button_interrupt() | 108 | button_interrupt() |
108 | 109 | ||
109 | which upon every interrupt from the button checks its state and reports it | 110 | which upon every interrupt from the button checks its state and reports it |
110 | via the | 111 | via the:: |
111 | 112 | ||
112 | input_report_key() | 113 | input_report_key() |
113 | 114 | ||
@@ -116,7 +117,7 @@ routine isn't reporting two same value events (press, press for example) to | |||
116 | the input system, because the input_report_* functions check that | 117 | the input system, because the input_report_* functions check that |
117 | themselves. | 118 | themselves. |
118 | 119 | ||
119 | Then there is the | 120 | Then there is the:: |
120 | 121 | ||
121 | input_sync() | 122 | input_sync() |
122 | 123 | ||
@@ -125,38 +126,38 @@ This doesn't seem important in the one button case, but is quite important | |||
125 | for for example mouse movement, where you don't want the X and Y values | 126 | for for example mouse movement, where you don't want the X and Y values |
126 | to be interpreted separately, because that'd result in a different movement. | 127 | to be interpreted separately, because that'd result in a different movement. |
127 | 128 | ||
128 | 1.2 dev->open() and dev->close() | 129 | dev->open() and dev->close() |
129 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | 130 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
130 | 131 | ||
131 | In case the driver has to repeatedly poll the device, because it doesn't | 132 | In case the driver has to repeatedly poll the device, because it doesn't |
132 | have an interrupt coming from it and the polling is too expensive to be done | 133 | have an interrupt coming from it and the polling is too expensive to be done |
133 | all the time, or if the device uses a valuable resource (eg. interrupt), it | 134 | all the time, or if the device uses a valuable resource (eg. interrupt), it |
134 | can use the open and close callback to know when it can stop polling or | 135 | can use the open and close callback to know when it can stop polling or |
135 | release the interrupt and when it must resume polling or grab the interrupt | 136 | release the interrupt and when it must resume polling or grab the interrupt |
136 | again. To do that, we would add this to our example driver: | 137 | again. To do that, we would add this to our example driver:: |
137 | 138 | ||
138 | static int button_open(struct input_dev *dev) | 139 | static int button_open(struct input_dev *dev) |
139 | { | 140 | { |
140 | if (request_irq(BUTTON_IRQ, button_interrupt, 0, "button", NULL)) { | 141 | if (request_irq(BUTTON_IRQ, button_interrupt, 0, "button", NULL)) { |
141 | printk(KERN_ERR "button.c: Can't allocate irq %d\n", button_irq); | 142 | printk(KERN_ERR "button.c: Can't allocate irq %d\n", button_irq); |
142 | return -EBUSY; | 143 | return -EBUSY; |
143 | } | 144 | } |
144 | 145 | ||
145 | return 0; | 146 | return 0; |
146 | } | 147 | } |
147 | 148 | ||
148 | static void button_close(struct input_dev *dev) | 149 | static void button_close(struct input_dev *dev) |
149 | { | 150 | { |
150 | free_irq(IRQ_AMIGA_VERTB, button_interrupt); | 151 | free_irq(IRQ_AMIGA_VERTB, button_interrupt); |
151 | } | 152 | } |
152 | 153 | ||
153 | static int __init button_init(void) | 154 | static int __init button_init(void) |
154 | { | 155 | { |
155 | ... | 156 | ... |
156 | button_dev->open = button_open; | 157 | button_dev->open = button_open; |
157 | button_dev->close = button_close; | 158 | button_dev->close = button_close; |
158 | ... | 159 | ... |
159 | } | 160 | } |
160 | 161 | ||
161 | Note that input core keeps track of number of users for the device and | 162 | Note that input core keeps track of number of users for the device and |
162 | makes sure that dev->open() is called only when the first user connects | 163 | makes sure that dev->open() is called only when the first user connects |
@@ -166,11 +167,11 @@ disconnects. Calls to both callbacks are serialized. | |||
166 | The open() callback should return a 0 in case of success or any nonzero value | 167 | The open() callback should return a 0 in case of success or any nonzero value |
167 | in case of failure. The close() callback (which is void) must always succeed. | 168 | in case of failure. The close() callback (which is void) must always succeed. |
168 | 169 | ||
169 | 1.3 Basic event types | 170 | Basic event types |
170 | ~~~~~~~~~~~~~~~~~~~~~ | 171 | ~~~~~~~~~~~~~~~~~ |
171 | 172 | ||
172 | The most simple event type is EV_KEY, which is used for keys and buttons. | 173 | The most simple event type is EV_KEY, which is used for keys and buttons. |
173 | It's reported to the input system via: | 174 | It's reported to the input system via:: |
174 | 175 | ||
175 | input_report_key(struct input_dev *dev, int code, int value) | 176 | input_report_key(struct input_dev *dev, int code, int value) |
176 | 177 | ||
@@ -188,7 +189,7 @@ events are namely for joysticks and digitizers - devices that do work in an | |||
188 | absolute coordinate systems. | 189 | absolute coordinate systems. |
189 | 190 | ||
190 | Having the device report EV_REL buttons is as simple as with EV_KEY, simply | 191 | Having the device report EV_REL buttons is as simple as with EV_KEY, simply |
191 | set the corresponding bits and call the | 192 | set the corresponding bits and call the:: |
192 | 193 | ||
193 | input_report_rel(struct input_dev *dev, int code, int value) | 194 | input_report_rel(struct input_dev *dev, int code, int value) |
194 | 195 | ||
@@ -197,14 +198,14 @@ function. Events are generated only for nonzero value. | |||
197 | However EV_ABS requires a little special care. Before calling | 198 | However EV_ABS requires a little special care. Before calling |
198 | input_register_device, you have to fill additional fields in the input_dev | 199 | input_register_device, you have to fill additional fields in the input_dev |
199 | struct for each absolute axis your device has. If our button device had also | 200 | struct for each absolute axis your device has. If our button device had also |
200 | the ABS_X axis: | 201 | the ABS_X axis:: |
201 | 202 | ||
202 | button_dev.absmin[ABS_X] = 0; | 203 | button_dev.absmin[ABS_X] = 0; |
203 | button_dev.absmax[ABS_X] = 255; | 204 | button_dev.absmax[ABS_X] = 255; |
204 | button_dev.absfuzz[ABS_X] = 4; | 205 | button_dev.absfuzz[ABS_X] = 4; |
205 | button_dev.absflat[ABS_X] = 8; | 206 | button_dev.absflat[ABS_X] = 8; |
206 | 207 | ||
207 | Or, you can just say: | 208 | Or, you can just say:: |
208 | 209 | ||
209 | input_set_abs_params(button_dev, ABS_X, 0, 255, 4, 8); | 210 | input_set_abs_params(button_dev, ABS_X, 0, 255, 4, 8); |
210 | 211 | ||
@@ -218,18 +219,18 @@ If you don't need absfuzz and absflat, you can set them to zero, which mean | |||
218 | that the thing is precise and always returns to exactly the center position | 219 | that the thing is precise and always returns to exactly the center position |
219 | (if it has any). | 220 | (if it has any). |
220 | 221 | ||
221 | 1.4 BITS_TO_LONGS(), BIT_WORD(), BIT_MASK() | 222 | BITS_TO_LONGS(), BIT_WORD(), BIT_MASK() |
222 | ~~~~~~~~~~~~~~~~~~~~~~~~~~ | 223 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
223 | 224 | ||
224 | These three macros from bitops.h help some bitfield computations: | 225 | These three macros from bitops.h help some bitfield computations:: |
225 | 226 | ||
226 | BITS_TO_LONGS(x) - returns the length of a bitfield array in longs for | 227 | BITS_TO_LONGS(x) - returns the length of a bitfield array in longs for |
227 | x bits | 228 | x bits |
228 | BIT_WORD(x) - returns the index in the array in longs for bit x | 229 | BIT_WORD(x) - returns the index in the array in longs for bit x |
229 | BIT_MASK(x) - returns the index in a long for bit x | 230 | BIT_MASK(x) - returns the index in a long for bit x |
230 | 231 | ||
231 | 1.5 The id* and name fields | 232 | The id* and name fields |
232 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | 233 | ~~~~~~~~~~~~~~~~~~~~~~~ |
233 | 234 | ||
234 | The dev->name should be set before registering the input device by the input | 235 | The dev->name should be set before registering the input device by the input |
235 | device driver. It's a string like 'Generic button device' containing a | 236 | device driver. It's a string like 'Generic button device' containing a |
@@ -245,8 +246,8 @@ driver. | |||
245 | 246 | ||
246 | The id and name fields can be passed to userland via the evdev interface. | 247 | The id and name fields can be passed to userland via the evdev interface. |
247 | 248 | ||
248 | 1.6 The keycode, keycodemax, keycodesize fields | 249 | The keycode, keycodemax, keycodesize fields |
249 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | 250 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
250 | 251 | ||
251 | These three fields should be used by input devices that have dense keymaps. | 252 | These three fields should be used by input devices that have dense keymaps. |
252 | The keycode is an array used to map from scancodes to input system keycodes. | 253 | The keycode is an array used to map from scancodes to input system keycodes. |
@@ -259,14 +260,15 @@ When a device has all 3 aforementioned fields filled in, the driver may | |||
259 | rely on kernel's default implementation of setting and querying keycode | 260 | rely on kernel's default implementation of setting and querying keycode |
260 | mappings. | 261 | mappings. |
261 | 262 | ||
262 | 1.7 dev->getkeycode() and dev->setkeycode() | 263 | dev->getkeycode() and dev->setkeycode() |
263 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | 264 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
265 | |||
264 | getkeycode() and setkeycode() callbacks allow drivers to override default | 266 | getkeycode() and setkeycode() callbacks allow drivers to override default |
265 | keycode/keycodesize/keycodemax mapping mechanism provided by input core | 267 | keycode/keycodesize/keycodemax mapping mechanism provided by input core |
266 | and implement sparse keycode maps. | 268 | and implement sparse keycode maps. |
267 | 269 | ||
268 | 1.8 Key autorepeat | 270 | Key autorepeat |
269 | ~~~~~~~~~~~~~~~~~~ | 271 | ~~~~~~~~~~~~~~ |
270 | 272 | ||
271 | ... is simple. It is handled by the input.c module. Hardware autorepeat is | 273 | ... is simple. It is handled by the input.c module. Hardware autorepeat is |
272 | not used, because it's not present in many devices and even where it is | 274 | not used, because it's not present in many devices and even where it is |
@@ -274,29 +276,30 @@ present, it is broken sometimes (at keyboards: Toshiba notebooks). To enable | |||
274 | autorepeat for your device, just set EV_REP in dev->evbit. All will be | 276 | autorepeat for your device, just set EV_REP in dev->evbit. All will be |
275 | handled by the input system. | 277 | handled by the input system. |
276 | 278 | ||
277 | 1.9 Other event types, handling output events | 279 | Other event types, handling output events |
278 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | 280 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
279 | 281 | ||
280 | The other event types up to now are: | 282 | The other event types up to now are: |
281 | 283 | ||
282 | EV_LED - used for the keyboard LEDs. | 284 | - EV_LED - used for the keyboard LEDs. |
283 | EV_SND - used for keyboard beeps. | 285 | - EV_SND - used for keyboard beeps. |
284 | 286 | ||
285 | They are very similar to for example key events, but they go in the other | 287 | They are very similar to for example key events, but they go in the other |
286 | direction - from the system to the input device driver. If your input device | 288 | direction - from the system to the input device driver. If your input device |
287 | driver can handle these events, it has to set the respective bits in evbit, | 289 | driver can handle these events, it has to set the respective bits in evbit, |
288 | *and* also the callback routine: | 290 | *and* also the callback routine:: |
289 | 291 | ||
290 | button_dev->event = button_event; | 292 | button_dev->event = button_event; |
291 | 293 | ||
292 | int button_event(struct input_dev *dev, unsigned int type, unsigned int code, int value); | 294 | int button_event(struct input_dev *dev, unsigned int type, |
293 | { | 295 | unsigned int code, int value) |
294 | if (type == EV_SND && code == SND_BELL) { | 296 | { |
295 | outb(value, BUTTON_BELL); | 297 | if (type == EV_SND && code == SND_BELL) { |
296 | return 0; | 298 | outb(value, BUTTON_BELL); |
297 | } | 299 | return 0; |
298 | return -1; | 300 | } |
299 | } | 301 | return -1; |
302 | } | ||
300 | 303 | ||
301 | This callback routine can be called from an interrupt or a BH (although that | 304 | This callback routine can be called from an interrupt or a BH (although that |
302 | isn't a rule), and thus must not sleep, and must not take too long to finish. | 305 | isn't a rule), and thus must not sleep, and must not take too long to finish. |