summaryrefslogtreecommitdiff
path: root/Documentation/usb/gadget_hid.rst
blob: 098d563040ccd6275ad4472434dcaa1d0640f64f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
===========================
Linux USB HID gadget driver
===========================

Introduction
============

The HID Gadget driver provides emulation of USB Human Interface
Devices (HID). The basic HID handling is done in the kernel,
and HID reports can be sent/received through I/O on the
/dev/hidgX character devices.

For more details about HID, see the developer page on
http://www.usb.org/developers/hidpage/

Configuration
=============

g_hid is a platform driver, so to use it you need to add
struct platform_device(s) to your platform code defining the
HID function descriptors you want to use - E.G. something
like::

  #include <linux/platform_device.h>
  #include <linux/usb/g_hid.h>

  /* hid descriptor for a keyboard */
  static struct hidg_func_descriptor my_hid_data = {
	.subclass		= 0, /* No subclass */
	.protocol		= 1, /* Keyboard */
	.report_length		= 8,
	.report_desc_length	= 63,
	.report_desc		= {
		0x05, 0x01,	/* USAGE_PAGE (Generic Desktop)	          */
		0x09, 0x06,	/* USAGE (Keyboard)                       */
		0xa1, 0x01,	/* COLLECTION (Application)               */
		0x05, 0x07,	/*   USAGE_PAGE (Keyboard)                */
		0x19, 0xe0,	/*   USAGE_MINIMUM (Keyboard LeftControl) */
		0x29, 0xe7,	/*   USAGE_MAXIMUM (Keyboard Right GUI)   */
		0x15, 0x00,	/*   LOGICAL_MINIMUM (0)                  */
		0x25, 0x01,	/*   LOGICAL_MAXIMUM (1)                  */
		0x75, 0x01,	/*   REPORT_SIZE (1)                      */
		0x95, 0x08,	/*   REPORT_COUNT (8)                     */
		0x81, 0x02,	/*   INPUT (Data,Var,Abs)                 */
		0x95, 0x01,	/*   REPORT_COUNT (1)                     */
		0x75, 0x08,	/*   REPORT_SIZE (8)                      */
		0x81, 0x03,	/*   INPUT (Cnst,Var,Abs)                 */
		0x95, 0x05,	/*   REPORT_COUNT (5)                     */
		0x75, 0x01,	/*   REPORT_SIZE (1)                      */
		0x05, 0x08,	/*   USAGE_PAGE (LEDs)                    */
		0x19, 0x01,	/*   USAGE_MINIMUM (Num Lock)             */
		0x29, 0x05,	/*   USAGE_MAXIMUM (Kana)                 */
		0x91, 0x02,	/*   OUTPUT (Data,Var,Abs)                */
		0x95, 0x01,	/*   REPORT_COUNT (1)                     */
		0x75, 0x03,	/*   REPORT_SIZE (3)                      */
		0x91, 0x03,	/*   OUTPUT (Cnst,Var,Abs)                */
		0x95, 0x06,	/*   REPORT_COUNT (6)                     */
		0x75, 0x08,	/*   REPORT_SIZE (8)                      */
		0x15, 0x00,	/*   LOGICAL_MINIMUM (0)                  */
		0x25, 0x65,	/*   LOGICAL_MAXIMUM (101)                */
		0x05, 0x07,	/*   USAGE_PAGE (Keyboard)                */
		0x19, 0x00,	/*   USAGE_MINIMUM (Reserved)             */
		0x29, 0x65,	/*   USAGE_MAXIMUM (Keyboard Application) */
		0x81, 0x00,	/*   INPUT (Data,Ary,Abs)                 */
		0xc0		/* END_COLLECTION                         */
	}
  };

  static struct platform_device my_hid = {
	.name			= "hidg",
	.id			= 0,
	.num_resources		= 0,
	.resource		= 0,
	.dev.platform_data	= &my_hid_data,
  };

You can add as many HID functions as you want, only limited by
the amount of interrupt endpoints your gadget driver supports.

Configuration with configfs
===========================

Instead of adding fake platform devices and drivers in order to pass
some data to the kernel, if HID is a part of a gadget composed with
configfs the hidg_func_descriptor.report_desc is passed to the kernel
by writing the appropriate stream of bytes to a configfs attribute.

Send and receive HID reports
============================

HID reports can be sent/received using read/write on the
/dev/hidgX character devices. See below for an example program
to do this.

hid_gadget_test is a small interactive program to test the HID
gadget driver. To use, point it at a hidg device and set the
device type (keyboard / mouse / joystick) - E.G.::

	# hid_gadget_test /dev/hidg0 keyboard

You are now in the prompt of hid_gadget_test. You can type any
combination of options and values. Available options and
values are listed at program start. In keyboard mode you can
send up to six values.

For example type: g i s t r --left-shift

Hit return and the corresponding report will be sent by the
HID gadget.

Another interesting example is the caps lock test. Type
--caps-lock and hit return. A report is then sent by the
gadget and you should receive the host answer, corresponding
to the caps lock LED status::

	--caps-lock
	recv report:2

With this command::

	# hid_gadget_test /dev/hidg1 mouse

You can test the mouse emulation. Values are two signed numbers.


Sample code::

    /* hid_gadget_test */

    #include <pthread.h>
    #include <string.h>
    #include <stdio.h>
    #include <ctype.h>
    #include <fcntl.h>
    #include <errno.h>
    #include <stdio.h>
    #include <stdlib.h>
    #include <unistd.h>

    #define BUF_LEN 512

    struct options {
	const char    *opt;
	unsigned char val;
  };

  static struct options kmod[] = {
	{.opt = "--left-ctrl",		.val = 0x01},
	{.opt = "--right-ctrl",		.val = 0x10},
	{.opt = "--left-shift",		.val = 0x02},
	{.opt = "--right-shift",	.val = 0x20},
	{.opt = "--left-alt",		.val = 0x04},
	{.opt = "--right-alt",		.val = 0x40},
	{.opt = "--left-meta",		.val = 0x08},
	{.opt = "--right-meta",		.val = 0x80},
	{.opt = NULL}
  };

  static struct options kval[] = {
	{.opt = "--return",	.val = 0x28},
	{.opt = "--esc",	.val = 0x29},
	{.opt = "--bckspc",	.val = 0x2a},
	{.opt = "--tab",	.val = 0x2b},
	{.opt = "--spacebar",	.val = 0x2c},
	{.opt = "--caps-lock",	.val = 0x39},
	{.opt = "--f1",		.val = 0x3a},
	{.opt = "--f2",		.val = 0x3b},
	{.opt = "--f3",		.val = 0x3c},
	{.opt = "--f4",		.val = 0x3d},
	{.opt = "--f5",		.val = 0x3e},
	{.opt = "--f6",		.val = 0x3f},
	{.opt = "--f7",		.val = 0x40},
	{.opt = "--f8",		.val = 0x41},
	{.opt = "--f9",		.val = 0x42},
	{.opt = "--f10",	.val = 0x43},
	{.opt = "--f11",	.val = 0x44},
	{.opt = "--f12",	.val = 0x45},
	{.opt = "--insert",	.val = 0x49},
	{.opt = "--home",	.val = 0x4a},
	{.opt = "--pageup",	.val = 0x4b},
	{.opt = "--del",	.val = 0x4c},
	{.opt = "--end",	.val = 0x4d},
	{.opt = "--pagedown",	.val = 0x4e},
	{.opt = "--right",	.val = 0x4f},
	{.opt = "--left",	.val = 0x50},
	{.opt = "--down",	.val = 0x51},
	{.opt = "--kp-enter",	.val = 0x58},
	{.opt = "--up",		.val = 0x52},
	{.opt = "--num-lock",	.val = 0x53},
	{.opt = NULL}
  };

  int keyboard_fill_report(char report[8], char buf[BUF_LEN], int *hold)
  {
	char *tok = strtok(buf, " ");
	int key = 0;
	int i = 0;

	for (; tok != NULL; tok = strtok(NULL, " ")) {

		if (strcmp(tok, "--quit") == 0)
			return -1;

		if (strcmp(tok, "--hold") == 0) {
			*hold = 1;
			continue;
		}

		if (key < 6) {
			for (i = 0; kval[i].opt != NULL; i++)
				if (strcmp(tok, kval[i].opt) == 0) {
					report[2 + key++] = kval[i].val;
					break;
				}
			if (kval[i].opt != NULL)
				continue;
		}

		if (key < 6)
			if (islower(tok[0])) {
				report[2 + key++] = (tok[0] - ('a' - 0x04));
				continue;
			}

		for (i = 0; kmod[i].opt != NULL; i++)
			if (strcmp(tok, kmod[i].opt) == 0) {
				report[0] = report[0] | kmod[i].val;
				break;
			}
		if (kmod[i].opt != NULL)
			continue;

		if (key < 6)
			fprintf(stderr, "unknown option: %s\n", tok);
	}
	return 8;
  }

  static struct options mmod[] = {
	{.opt = "--b1", .val = 0x01},
	{.opt = "--b2", .val = 0x02},
	{.opt = "--b3", .val = 0x04},
	{.opt = NULL}
  };

  int mouse_fill_report(char report[8], char buf[BUF_LEN], int *hold)
  {
	char *tok = strtok(buf, " ");
	int mvt = 0;
	int i = 0;
	for (; tok != NULL; tok = strtok(NULL, " ")) {

		if (strcmp(tok, "--quit") == 0)
			return -1;

		if (strcmp(tok, "--hold") == 0) {
			*hold = 1;
			continue;
		}

		for (i = 0; mmod[i].opt != NULL; i++)
			if (strcmp(tok, mmod[i].opt) == 0) {
				report[0] = report[0] | mmod[i].val;
				break;
			}
		if (mmod[i].opt != NULL)
			continue;

		if (!(tok[0] == '-' && tok[1] == '-') && mvt < 2) {
			errno = 0;
			report[1 + mvt++] = (char)strtol(tok, NULL, 0);
			if (errno != 0) {
				fprintf(stderr, "Bad value:'%s'\n", tok);
				report[1 + mvt--] = 0;
			}
			continue;
		}

		fprintf(stderr, "unknown option: %s\n", tok);
	}
	return 3;
  }

  static struct options jmod[] = {
	{.opt = "--b1",		.val = 0x10},
	{.opt = "--b2",		.val = 0x20},
	{.opt = "--b3",		.val = 0x40},
	{.opt = "--b4",		.val = 0x80},
	{.opt = "--hat1",	.val = 0x00},
	{.opt = "--hat2",	.val = 0x01},
	{.opt = "--hat3",	.val = 0x02},
	{.opt = "--hat4",	.val = 0x03},
	{.opt = "--hatneutral",	.val = 0x04},
	{.opt = NULL}
  };

  int joystick_fill_report(char report[8], char buf[BUF_LEN], int *hold)
  {
	char *tok = strtok(buf, " ");
	int mvt = 0;
	int i = 0;

	*hold = 1;

	/* set default hat position: neutral */
	report[3] = 0x04;

	for (; tok != NULL; tok = strtok(NULL, " ")) {

		if (strcmp(tok, "--quit") == 0)
			return -1;

		for (i = 0; jmod[i].opt != NULL; i++)
			if (strcmp(tok, jmod[i].opt) == 0) {
				report[3] = (report[3] & 0xF0) | jmod[i].val;
				break;
			}
		if (jmod[i].opt != NULL)
			continue;

		if (!(tok[0] == '-' && tok[1] == '-') && mvt < 3) {
			errno = 0;
			report[mvt++] = (char)strtol(tok, NULL, 0);
			if (errno != 0) {
				fprintf(stderr, "Bad value:'%s'\n", tok);
				report[mvt--] = 0;
			}
			continue;
		}

		fprintf(stderr, "unknown option: %s\n", tok);
	}
	return 4;
  }

  void print_options(char c)
  {
	int i = 0;

	if (c == 'k') {
		printf("	keyboard options:\n"
		       "		--hold\n");
		for (i = 0; kmod[i].opt != NULL; i++)
			printf("\t\t%s\n", kmod[i].opt);
		printf("\n	keyboard values:\n"
		       "		[a-z] or\n");
		for (i = 0; kval[i].opt != NULL; i++)
			printf("\t\t%-8s%s", kval[i].opt, i % 2 ? "\n" : "");
		printf("\n");
	} else if (c == 'm') {
		printf("	mouse options:\n"
		       "		--hold\n");
		for (i = 0; mmod[i].opt != NULL; i++)
			printf("\t\t%s\n", mmod[i].opt);
		printf("\n	mouse values:\n"
		       "		Two signed numbers\n"
		       "--quit to close\n");
	} else {
		printf("	joystick options:\n");
		for (i = 0; jmod[i].opt != NULL; i++)
			printf("\t\t%s\n", jmod[i].opt);
		printf("\n	joystick values:\n"
		       "		three signed numbers\n"
		       "--quit to close\n");
	}
  }

  int main(int argc, const char *argv[])
  {
	const char *filename = NULL;
	int fd = 0;
	char buf[BUF_LEN];
	int cmd_len;
	char report[8];
	int to_send = 8;
	int hold = 0;
	fd_set rfds;
	int retval, i;

	if (argc < 3) {
		fprintf(stderr, "Usage: %s devname mouse|keyboard|joystick\n",
			argv[0]);
		return 1;
	}

	if (argv[2][0] != 'k' && argv[2][0] != 'm' && argv[2][0] != 'j')
	  return 2;

	filename = argv[1];

	if ((fd = open(filename, O_RDWR, 0666)) == -1) {
		perror(filename);
		return 3;
	}

	print_options(argv[2][0]);

	while (42) {

		FD_ZERO(&rfds);
		FD_SET(STDIN_FILENO, &rfds);
		FD_SET(fd, &rfds);

		retval = select(fd + 1, &rfds, NULL, NULL, NULL);
		if (retval == -1 && errno == EINTR)
			continue;
		if (retval < 0) {
			perror("select()");
			return 4;
		}

		if (FD_ISSET(fd, &rfds)) {
			cmd_len = read(fd, buf, BUF_LEN - 1);
			printf("recv report:");
			for (i = 0; i < cmd_len; i++)
				printf(" %02x", buf[i]);
			printf("\n");
		}

		if (FD_ISSET(STDIN_FILENO, &rfds)) {
			memset(report, 0x0, sizeof(report));
			cmd_len = read(STDIN_FILENO, buf, BUF_LEN - 1);

			if (cmd_len == 0)
				break;

			buf[cmd_len - 1] = '\0';
			hold = 0;

			memset(report, 0x0, sizeof(report));
			if (argv[2][0] == 'k')
				to_send = keyboard_fill_report(report, buf, &hold);
			else if (argv[2][0] == 'm')
				to_send = mouse_fill_report(report, buf, &hold);
			else
				to_send = joystick_fill_report(report, buf, &hold);

			if (to_send == -1)
				break;

			if (write(fd, report, to_send) != to_send) {
				perror(filename);
				return 5;
			}
			if (!hold) {
				memset(report, 0x0, sizeof(report));
				if (write(fd, report, to_send) != to_send) {
					perror(filename);
					return 6;
				}
			}
		}
	}

	close(fd);
	return 0;
  }