summaryrefslogtreecommitdiffstats
path: root/samples/uhid/uhid-example.c
blob: b72d645ce8285f8cfea7ad036dee4b340469eee0 (plain) (blame)
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
458
459
460
461
462
463
464
465
// SPDX-License-Identifier: GPL-2.0
/*
 * UHID Example
 *
 * Copyright (c) 2012-2013 David Herrmann <dh.herrmann@gmail.com>
 *
 * The code may be used by anyone for any purpose,
 * and can serve as a starting point for developing
 * applications using uhid.
 */

/*
 * UHID Example
 * This example emulates a basic 3 buttons mouse with wheel over UHID. Run this
 * program as root and then use the following keys to control the mouse:
 *   q: Quit the application
 *   1: Toggle left button (down, up, ...)
 *   2: Toggle right button
 *   3: Toggle middle button
 *   a: Move mouse left
 *   d: Move mouse right
 *   w: Move mouse up
 *   s: Move mouse down
 *   r: Move wheel up
 *   f: Move wheel down
 *
 * Additionally to 3 button mouse, 3 keyboard LEDs are also supported (LED_NUML,
 * LED_CAPSL and LED_SCROLLL). The device doesn't generate any related keyboard
 * events, though. You need to manually write the EV_LED/LED_XY/1 activation
 * input event to the evdev device to see it being sent to this device.
 *
 * If uhid is not available as /dev/uhid, then you can pass a different path as
 * first argument.
 * If <linux/uhid.h> is not installed in /usr, then compile this with:
 *   gcc -o ./uhid_test -Wall -I./include ./samples/uhid/uhid-example.c
 * And ignore the warning about kernel headers. However, it is recommended to
 * use the installed uhid.h if available.
 */

#include <errno.h>
#include <fcntl.h>
#include <poll.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>
#include <linux/uhid.h>

/*
 * HID Report Desciptor
 * We emulate a basic 3 button mouse with wheel and 3 keyboard LEDs. This is
 * the report-descriptor as the kernel will parse it:
 *
 * INPUT(1)[INPUT]
 *   Field(0)
 *     Physical(GenericDesktop.Pointer)
 *     Application(GenericDesktop.Mouse)
 *     Usage(3)
 *       Button.0001
 *       Button.0002
 *       Button.0003
 *     Logical Minimum(0)
 *     Logical Maximum(1)
 *     Report Size(1)
 *     Report Count(3)
 *     Report Offset(0)
 *     Flags( Variable Absolute )
 *   Field(1)
 *     Physical(GenericDesktop.Pointer)
 *     Application(GenericDesktop.Mouse)
 *     Usage(3)
 *       GenericDesktop.X
 *       GenericDesktop.Y
 *       GenericDesktop.Wheel
 *     Logical Minimum(-128)
 *     Logical Maximum(127)
 *     Report Size(8)
 *     Report Count(3)
 *     Report Offset(8)
 *     Flags( Variable Relative )
 * OUTPUT(2)[OUTPUT]
 *   Field(0)
 *     Application(GenericDesktop.Keyboard)
 *     Usage(3)
 *       LED.NumLock
 *       LED.CapsLock
 *       LED.ScrollLock
 *     Logical Minimum(0)
 *     Logical Maximum(1)
 *     Report Size(1)
 *     Report Count(3)
 *     Report Offset(0)
 *     Flags( Variable Absolute )
 *
 * This is the mapping that we expect:
 *   Button.0001 ---> Key.LeftBtn
 *   Button.0002 ---> Key.RightBtn
 *   Button.0003 ---> Key.MiddleBtn
 *   GenericDesktop.X ---> Relative.X
 *   GenericDesktop.Y ---> Relative.Y
 *   GenericDesktop.Wheel ---> Relative.Wheel
 *   LED.NumLock ---> LED.NumLock
 *   LED.CapsLock ---> LED.CapsLock
 *   LED.ScrollLock ---> LED.ScrollLock
 *
 * This information can be verified by reading /sys/kernel/debug/hid/<dev>/rdesc
 * This file should print the same information as showed above.
 */

static unsigned char rdesc[] = {
	0x05, 0x01,	/* USAGE_PAGE (Generic Desktop) */
	0x09, 0x02,	/* USAGE (Mouse) */
	0xa1, 0x01,	/* COLLECTION (Application) */
	0x09, 0x01,		/* USAGE (Pointer) */
	0xa1, 0x00,		/* COLLECTION (Physical) */
	0x85, 0x01,			/* REPORT_ID (1) */
	0x05, 0x09,			/* USAGE_PAGE (Button) */
	0x19, 0x01,			/* USAGE_MINIMUM (Button 1) */
	0x29, 0x03,			/* USAGE_MAXIMUM (Button 3) */
	0x15, 0x00,			/* LOGICAL_MINIMUM (0) */
	0x25, 0x01,			/* LOGICAL_MAXIMUM (1) */
	0x95, 0x03,			/* REPORT_COUNT (3) */
	0x75, 0x01,			/* REPORT_SIZE (1) */
	0x81, 0x02,			/* INPUT (Data,Var,Abs) */
	0x95, 0x01,			/* REPORT_COUNT (1) */
	0x75, 0x05,			/* REPORT_SIZE (5) */
	0x81, 0x01,			/* INPUT (Cnst,Var,Abs) */
	0x05, 0x01,			/* USAGE_PAGE (Generic Desktop) */
	0x09, 0x30,			/* USAGE (X) */
	0x09, 0x31,			/* USAGE (Y) */
	0x09, 0x38,			/* USAGE (WHEEL) */
	0x15, 0x81,			/* LOGICAL_MINIMUM (-127) */
	0x25, 0x7f,			/* LOGICAL_MAXIMUM (127) */
	0x75, 0x08,			/* REPORT_SIZE (8) */
	0x95, 0x03,			/* REPORT_COUNT (3) */
	0x81, 0x06,			/* INPUT (Data,Var,Rel) */
	0xc0,			/* END_COLLECTION */
	0xc0,		/* END_COLLECTION */
	0x05, 0x01,	/* USAGE_PAGE (Generic Desktop) */
	0x09, 0x06,	/* USAGE (Keyboard) */
	0xa1, 0x01,	/* COLLECTION (Application) */
	0x85, 0x02,		/* REPORT_ID (2) */
	0x05, 0x08,		/* USAGE_PAGE (Led) */
	0x19, 0x01,		/* USAGE_MINIMUM (1) */
	0x29, 0x03,		/* USAGE_MAXIMUM (3) */
	0x15, 0x00,		/* LOGICAL_MINIMUM (0) */
	0x25, 0x01,		/* LOGICAL_MAXIMUM (1) */
	0x95, 0x03,		/* REPORT_COUNT (3) */
	0x75, 0x01,		/* REPORT_SIZE (1) */
	0x91, 0x02,		/* Output (Data,Var,Abs) */
	0x95, 0x01,		/* REPORT_COUNT (1) */
	0x75, 0x05,		/* REPORT_SIZE (5) */
	0x91, 0x01,		/* Output (Cnst,Var,Abs) */
	0xc0,		/* END_COLLECTION */
};

static int uhid_write(int fd, const struct uhid_event *ev)
{
	ssize_t ret;

	ret = write(fd, ev, sizeof(*ev));
	if (ret < 0) {
		fprintf(stderr, "Cannot write to uhid: %m\n");
		return -errno;
	} else if (ret != sizeof(*ev)) {
		fprintf(stderr, "Wrong size written to uhid: %ld != %lu\n",
			ret, sizeof(ev));
		return -EFAULT;
	} else {
		return 0;
	}
}

static int create(int fd)
{
	struct uhid_event ev;

	memset(&ev, 0, sizeof(ev));
	ev.type = UHID_CREATE;
	strcpy((char*)ev.u.create.name, "test-uhid-device");
	ev.u.create.rd_data = rdesc;
	ev.u.create.rd_size = sizeof(rdesc);
	ev.u.create.bus = BUS_USB;
	ev.u.create.vendor = 0x15d9;
	ev.u.create.product = 0x0a37;
	ev.u.create.version = 0;
	ev.u.create.country = 0;

	return uhid_write(fd, &ev);
}

static void destroy(int fd)
{
	struct uhid_event ev;

	memset(&ev, 0, sizeof(ev));
	ev.type = UHID_DESTROY;

	uhid_write(fd, &ev);
}

/* This parses raw output reports sent by the kernel to the device. A normal
 * uhid program shouldn't do this but instead just forward the raw report.
 * However, for ducomentational purposes, we try to detect LED events here and
 * print debug messages for it. */
static void handle_output(struct uhid_event *ev)
{
	/* LED messages are adverised via OUTPUT reports; ignore the rest */
	if (ev->u.output.rtype != UHID_OUTPUT_REPORT)
		return;
	/* LED reports have length 2 bytes */
	if (ev->u.output.size != 2)
		return;
	/* first byte is report-id which is 0x02 for LEDs in our rdesc */
	if (ev->u.output.data[0] != 0x2)
		return;

	/* print flags payload */
	fprintf(stderr, "LED output report received with flags %x\n",
		ev->u.output.data[1]);
}

static int event(int fd)
{
	struct uhid_event ev;
	ssize_t ret;

	memset(&ev, 0, sizeof(ev));
	ret = read(fd, &ev, sizeof(ev));
	if (ret == 0) {
		fprintf(stderr, "Read HUP on uhid-cdev\n");
		return -EFAULT;
	} else if (ret < 0) {
		fprintf(stderr, "Cannot read uhid-cdev: %m\n");
		return -errno;
	} else if (ret != sizeof(ev)) {
		fprintf(stderr, "Invalid size read from uhid-dev: %ld != %lu\n",
			ret, sizeof(ev));
		return -EFAULT;
	}

	switch (ev.type) {
	case UHID_START:
		fprintf(stderr, "UHID_START from uhid-dev\n");
		break;
	case UHID_STOP:
		fprintf(stderr, "UHID_STOP from uhid-dev\n");
		break;
	case UHID_OPEN:
		fprintf(stderr, "UHID_OPEN from uhid-dev\n");
		break;
	case UHID_CLOSE:
		fprintf(stderr, "UHID_CLOSE from uhid-dev\n");
		break;
	case UHID_OUTPUT:
		fprintf(stderr, "UHID_OUTPUT from uhid-dev\n");
		handle_output(&ev);
		break;
	case UHID_OUTPUT_EV:
		fprintf(stderr, "UHID_OUTPUT_EV from uhid-dev\n");
		break;
	default:
		fprintf(stderr, "Invalid event from uhid-dev: %u\n", ev.type);
	}

	return 0;
}

static bool btn1_down;
static bool btn2_down;
static bool btn3_down;
static signed char abs_hor;
static signed char abs_ver;
static signed char wheel;

static int send_event(int fd)
{
	struct uhid_event ev;

	memset(&ev, 0, sizeof(ev));
	ev.type = UHID_INPUT;
	ev.u.input.size = 5;

	ev.u.input.data[0] = 0x1;
	if (btn1_down)
		ev.u.input.data[1] |= 0x1;
	if (btn2_down)
		ev.u.input.data[1] |= 0x2;
	if (btn3_down)
		ev.u.input.data[1] |= 0x4;

	ev.u.input.data[2] = abs_hor;
	ev.u.input.data[3] = abs_ver;
	ev.u.input.data[4] = wheel;

	return uhid_write(fd, &ev);
}

static int keyboard(int fd)
{
	char buf[128];
	ssize_t ret, i;

	ret = read(STDIN_FILENO, buf, sizeof(buf));
	if (ret == 0) {
		fprintf(stderr, "Read HUP on stdin\n");
		return -EFAULT;
	} else if (ret < 0) {
		fprintf(stderr, "Cannot read stdin: %m\n");
		return -errno;
	}

	for (i = 0; i < ret; ++i) {
		switch (buf[i]) {
		case '1':
			btn1_down = !btn1_down;
			ret = send_event(fd);
			if (ret)
				return ret;
			break;
		case '2':
			btn2_down = !btn2_down;
			ret = send_event(fd);
			if (ret)
				return ret;
			break;
		case '3':
			btn3_down = !btn3_down;
			ret = send_event(fd);
			if (ret)
				return ret;
			break;
		case 'a':
			abs_hor = -20;
			ret = send_event(fd);
			abs_hor = 0;
			if (ret)
				return ret;
			break;
		case 'd':
			abs_hor = 20;
			ret = send_event(fd);
			abs_hor = 0;
			if (ret)
				return ret;
			break;
		case 'w':
			abs_ver = -20;
			ret = send_event(fd);
			abs_ver = 0;
			if (ret)
				return ret;
			break;
		case 's':
			abs_ver = 20;
			ret = send_event(fd);
			abs_ver = 0;
			if (ret)
				return ret;
			break;
		case 'r':
			wheel = 1;
			ret = send_event(fd);
			wheel = 0;
			if (ret)
				return ret;
			break;
		case 'f':
			wheel = -1;
			ret = send_event(fd);
			wheel = 0;
			if (ret)
				return ret;
			break;
		case 'q':
			return -ECANCELED;
		default:
			fprintf(stderr, "Invalid input: %c\n", buf[i]);
		}
	}

	return 0;
}

int main(int argc, char **argv)
{
	int fd;
	const char *path = "/dev/uhid";
	struct pollfd pfds[2];
	int ret;
	struct termios state;

	ret = tcgetattr(STDIN_FILENO, &state);
	if (ret) {
		fprintf(stderr, "Cannot get tty state\n");
	} else {
		state.c_lflag &= ~ICANON;
		state.c_cc[VMIN] = 1;
		ret = tcsetattr(STDIN_FILENO, TCSANOW, &state);
		if (ret)
			fprintf(stderr, "Cannot set tty state\n");
	}

	if (argc >= 2) {
		if (!strcmp(argv[1], "-h") || !strcmp(argv[1], "--help")) {
			fprintf(stderr, "Usage: %s [%s]\n", argv[0], path);
			return EXIT_SUCCESS;
		} else {
			path = argv[1];
		}
	}

	fprintf(stderr, "Open uhid-cdev %s\n", path);
	fd = open(path, O_RDWR | O_CLOEXEC);
	if (fd < 0) {
		fprintf(stderr, "Cannot open uhid-cdev %s: %m\n", path);
		return EXIT_FAILURE;
	}

	fprintf(stderr, "Create uhid device\n");
	ret = create(fd);
	if (ret) {
		close(fd);
		return EXIT_FAILURE;
	}

	pfds[0].fd = STDIN_FILENO;
	pfds[0].events = POLLIN;
	pfds[1].fd = fd;
	pfds[1].events = POLLIN;

	fprintf(stderr, "Press 'q' to quit...\n");
	while (1) {
		ret = poll(pfds, 2, -1);
		if (ret < 0) {
			fprintf(stderr, "Cannot poll for fds: %m\n");
			break;
		}
		if (pfds[0].revents & POLLHUP) {
			fprintf(stderr, "Received HUP on stdin\n");
			break;
		}
		if (pfds[1].revents & POLLHUP) {
			fprintf(stderr, "Received HUP on uhid-cdev\n");
			break;
		}

		if (pfds[0].revents & POLLIN) {
			ret = keyboard(fd);
			if (ret)
				break;
		}
		if (pfds[1].revents & POLLIN) {
			ret = event(fd);
			if (ret)
				break;
		}
	}

	fprintf(stderr, "Destroy uhid device\n");
	destroy(fd);
	return EXIT_SUCCESS;
}