xref: /freebsd/sys/dev/evdev/evdev_mt.c (revision 5e3190f700637fcfc1a52daeaa4a031fdd2557c7)
1 /*-
2  * Copyright (c) 2016, 2020 Vladimir Kondratyev <wulf@FreeBSD.org>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  */
26 /*-
27  * Copyright (c) 2015, 2016 Ulf Brosziewski
28  *
29  * Permission to use, copy, modify, and distribute this software for any
30  * purpose with or without fee is hereby granted, provided that the above
31  * copyright notice and this permission notice appear in all copies.
32  *
33  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
34  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
35  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
36  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
37  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
38  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
39  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
40  */
41 
42 #include <sys/param.h>
43 #include <sys/lock.h>
44 #include <sys/malloc.h>
45 #include <sys/mutex.h>
46 #include <sys/systm.h>
47 
48 #include <dev/evdev/evdev.h>
49 #include <dev/evdev/evdev_private.h>
50 #include <dev/evdev/input.h>
51 
52 #ifdef DEBUG
53 #define	debugf(fmt, args...)	printf("evdev: " fmt "\n", ##args)
54 #else
55 #define	debugf(fmt, args...)
56 #endif
57 
58 typedef	u_int	slotset_t;
59 
60 _Static_assert(MAX_MT_SLOTS < sizeof(slotset_t) * 8, "MAX_MT_SLOTS too big");
61 
62 #define FOREACHBIT(v, i) \
63 	for ((i) = ffs(v) - 1; (i) != -1; (i) = ffs((v) & (~1 << (i))) - 1)
64 
65 struct {
66 	uint16_t	mt;
67 	uint16_t	st;
68 	int32_t		max;
69 } static evdev_mtstmap[] = {
70 	{ ABS_MT_POSITION_X,	ABS_X,		0 },
71 	{ ABS_MT_POSITION_Y,	ABS_Y,		0 },
72 	{ ABS_MT_PRESSURE,	ABS_PRESSURE,	255 },
73 	{ ABS_MT_TOUCH_MAJOR,	ABS_TOOL_WIDTH,	15 },
74 };
75 
76 struct evdev_mt {
77 	int			last_reported_slot;
78 	uint16_t		tracking_id;
79 	int32_t			tracking_ids[MAX_MT_SLOTS];
80 	bool			type_a;
81 	u_int			mtst_events;
82 	/* the set of slots with active touches */
83 	slotset_t		touches;
84 	/* the set of slots with unsynchronized state */
85 	slotset_t		frame;
86 	/* the set of slots to match with active touches */
87 	slotset_t		match_frame;
88 	int			match_slot;
89 	union evdev_mt_slot	*match_slots;
90 	int			*matrix;
91 	union evdev_mt_slot	slots[];
92 };
93 
94 static void	evdev_mt_support_st_compat(struct evdev_dev *);
95 static void	evdev_mt_send_st_compat(struct evdev_dev *);
96 static void	evdev_mt_send_autorel(struct evdev_dev *);
97 static void	evdev_mt_replay_events(struct evdev_dev *);
98 
99 static inline int
100 ffc_slot(struct evdev_dev *evdev, slotset_t slots)
101 {
102 	return (ffs(~slots & ((2U << MAXIMAL_MT_SLOT(evdev)) - 1)) - 1);
103 }
104 
105 void
106 evdev_mt_init(struct evdev_dev *evdev)
107 {
108 	struct evdev_mt *mt;
109 	size_t size = offsetof(struct evdev_mt, slots);
110 	int slot, slots;
111 	bool type_a;
112 
113 	type_a = !bit_test(evdev->ev_abs_flags, ABS_MT_SLOT);
114 	if (type_a) {
115 		/* Add events produced by MT type A to type B converter */
116 		evdev_support_abs(evdev,
117 		    ABS_MT_SLOT, 0, MAX_MT_SLOTS - 1, 0, 0, 0);
118 		evdev_support_abs(evdev,
119 		    ABS_MT_TRACKING_ID, -1, MAX_MT_SLOTS - 1, 0, 0, 0);
120 	}
121 
122 	slots = MAXIMAL_MT_SLOT(evdev) + 1;
123 	size += sizeof(mt->slots[0]) * slots;
124 	if (bit_test(evdev->ev_flags, EVDEV_FLAG_MT_TRACK)) {
125 		size += sizeof(mt->match_slots[0]) * slots;
126 		size += sizeof(mt->matrix[0]) * (slots + 6) * slots;
127 	}
128 
129 	mt = malloc(size, M_EVDEV, M_WAITOK | M_ZERO);
130 	evdev->ev_mt = mt;
131 	mt->type_a = type_a;
132 
133 	if (bit_test(evdev->ev_flags, EVDEV_FLAG_MT_TRACK)) {
134 		mt->match_slots = mt->slots + slots;
135 		mt->matrix = (int *)(mt->match_slots + slots);
136 	}
137 
138 	/* Initialize multitouch protocol type B states */
139 	for (slot = 0; slot < slots; slot++)
140 		mt->slots[slot].id = -1;
141 
142 	if (!bit_test(evdev->ev_flags, EVDEV_FLAG_MT_KEEPID))
143 		evdev_support_abs(evdev,
144 		    ABS_MT_TRACKING_ID, -1, UINT16_MAX, 0, 0, 0);
145 	if (bit_test(evdev->ev_flags, EVDEV_FLAG_MT_STCOMPAT))
146 		evdev_mt_support_st_compat(evdev);
147 }
148 
149 void
150 evdev_mt_free(struct evdev_dev *evdev)
151 {
152 	free(evdev->ev_mt, M_EVDEV);
153 }
154 
155 void
156 evdev_mt_sync_frame(struct evdev_dev *evdev)
157 {
158 	if (bit_test(evdev->ev_flags, EVDEV_FLAG_MT_TRACK))
159 		evdev_mt_replay_events(evdev);
160 	if (bit_test(evdev->ev_flags, EVDEV_FLAG_MT_AUTOREL))
161 		evdev_mt_send_autorel(evdev);
162 	if (evdev->ev_report_opened &&
163 	    bit_test(evdev->ev_flags, EVDEV_FLAG_MT_STCOMPAT))
164 		evdev_mt_send_st_compat(evdev);
165 	evdev->ev_mt->frame = 0;
166 }
167 
168 static void
169 evdev_mt_send_slot(struct evdev_dev *evdev, int slot,
170     union evdev_mt_slot *state)
171 {
172 	int i;
173 	bool type_a = !bit_test(evdev->ev_abs_flags, ABS_MT_SLOT);
174 
175 	EVDEV_LOCK_ASSERT(evdev);
176 	MPASS(type_a || (slot >= 0 && slot <= MAXIMAL_MT_SLOT(evdev)));
177 	MPASS(!type_a || state != NULL);
178 
179 	if (!type_a) {
180 		evdev_send_event(evdev, EV_ABS, ABS_MT_SLOT, slot);
181 		if (state == NULL) {
182 			evdev_send_event(evdev, EV_ABS, ABS_MT_TRACKING_ID, -1);
183 			return;
184 		}
185 	}
186 	bit_foreach_at(evdev->ev_abs_flags, ABS_MT_FIRST, ABS_MT_LAST + 1, i)
187 		evdev_send_event(evdev, EV_ABS, i,
188 		    state->val[ABS_MT_INDEX(i)]);
189 	if (type_a)
190 		evdev_send_event(evdev, EV_SYN, SYN_MT_REPORT, 1);
191 }
192 
193 int
194 evdev_mt_push_slot(struct evdev_dev *evdev, int slot,
195     union evdev_mt_slot *state)
196 {
197 	struct evdev_mt *mt = evdev->ev_mt;
198 	bool type_a = !bit_test(evdev->ev_abs_flags, ABS_MT_SLOT);
199 
200 	if ((type_a || (mt != NULL && mt->type_a)) && state == NULL)
201 		return (EINVAL);
202 	if (!type_a && (slot < 0 || slot > MAXIMAL_MT_SLOT(evdev)))
203 		return (EINVAL);
204 
205 	EVDEV_ENTER(evdev);
206 	if (bit_test(evdev->ev_flags, EVDEV_FLAG_MT_TRACK) && mt->type_a) {
207 		mt->match_slots[mt->match_slot] = *state;
208 		evdev_mt_record_event(evdev, EV_SYN, SYN_MT_REPORT, 1);
209 	} else if (bit_test(evdev->ev_flags, EVDEV_FLAG_MT_TRACK)) {
210 		evdev_mt_record_event(evdev, EV_ABS, ABS_MT_SLOT, slot);
211 		if (state != NULL)
212 			mt->match_slots[mt->match_slot] = *state;
213 		else
214 			evdev_mt_record_event(evdev, EV_ABS,
215 			    ABS_MT_TRACKING_ID, -1);
216 	} else
217 		evdev_mt_send_slot(evdev, slot, state);
218 	EVDEV_EXIT(evdev);
219 
220 	return (0);
221 }
222 
223 /*
224  * Find a minimum-weight matching for an m-by-n matrix.
225  *
226  * m must be greater than or equal to n. The size of the buffer must be
227  * at least 3m + 3n.
228  *
229  * On return, the first m elements of the buffer contain the row-to-
230  * column mappings, i.e., buffer[i] is the column index for row i, or -1
231  * if there is no assignment for that row (which may happen if n < m).
232  *
233  * Wrong results because of overflows will not occur with input values
234  * in the range of 0 to INT_MAX / 2 inclusive.
235  *
236  * The function applies the Dinic-Kronrod algorithm. It is not modern or
237  * popular, but it seems to be a good choice for small matrices at least.
238  * The original form of the algorithm is modified as follows: There is no
239  * initial search for row minima, the initial assignments are in a
240  * "virtual" column with the index -1 and zero values. This permits inputs
241  * with n < m, and it simplifies the reassignments.
242  */
243 static void
244 evdev_mt_matching(int *matrix, int m, int n, int *buffer)
245 {
246 	int i, j, k, d, e, row, col, delta;
247 	int *p;
248 	int *r2c = buffer;	/* row-to-column assignments */
249 	int *red = r2c + m;	/* reduced values of the assignments */
250 	int *mc = red + m;	/* row-wise minimal elements of cs */
251 	int *cs = mc + m;	/* the column set */
252 	int *c2r = cs + n;	/* column-to-row assignments in cs */
253 	int *cd = c2r + n;	/* column deltas (reduction) */
254 
255 	for (p = r2c; p < red; *p++ = -1) {}
256 	for (; p < mc; *p++ = 0) {}
257 	for (col = 0; col < n; col++) {
258 		delta = INT_MAX;
259 		for (i = 0, p = matrix + col; i < m; i++, p += n) {
260 			d = *p - red[i];
261 			if (d < delta || (d == delta && r2c[i] < 0)) {
262 				delta = d;
263 				row = i;
264 			}
265 		}
266 		cd[col] = delta;
267 		if (r2c[row] < 0) {
268 			r2c[row] = col;
269 			continue;
270 		}
271 		for (p = mc; p < cs; *p++ = col) {}
272 		for (k = 0; (j = r2c[row]) >= 0;) {
273 			cs[k++] = j;
274 			c2r[j] = row;
275 			mc[row] -= n;
276 			delta = INT_MAX;
277 			for (i = 0, p = matrix; i < m; i++, p += n)
278 				if (mc[i] >= 0) {
279 					d = p[mc[i]] - cd[mc[i]];
280 					e = p[j] - cd[j];
281 					if (e < d) {
282 						d = e;
283 						mc[i] = j;
284 					}
285 					d -= red[i];
286 					if (d < delta || (d == delta
287 					    && r2c[i] < 0)) {
288 						delta = d;
289 						row = i;
290 					}
291 				}
292 			cd[col] += delta;
293 			for (i = 0; i < k; i++) {
294 				cd[cs[i]] += delta;
295 				red[c2r[cs[i]]] -= delta;
296 			}
297 		}
298 		for (j = mc[row]; (r2c[row] = j) != col;) {
299 			row = c2r[j];
300 			j = mc[row] + n;
301 		}
302 	}
303 }
304 
305 /*
306  * Assign tracking IDs to the points in the pt array.  The tracking ID
307  * assignment pairs the points with points of the previous frame in
308  * such a way that the sum of the squared distances is minimal.  Using
309  * squares instead of simple distances favours assignments with more uniform
310  * distances, and it is faster.
311  * Set tracking id to -1 for unassigned (new) points.
312  */
313 void
314 evdev_mt_match_frame(struct evdev_dev *evdev, union evdev_mt_slot *pt,
315     int size)
316 {
317 	struct evdev_mt *mt = evdev->ev_mt;
318 	int i, j, m, n, dx, dy, slot, num_touches;
319 	int *p, *r2c, *c2r;
320 
321 	EVDEV_LOCK_ASSERT(evdev);
322 	MPASS(mt->matrix != NULL);
323 	MPASS(size >= 0 && size <= MAXIMAL_MT_SLOT(evdev) + 1);
324 
325 	if (size == 0)
326 		return;
327 
328 	p = mt->matrix;
329 	num_touches = bitcount(mt->touches);
330 	if (num_touches >= size) {
331 		FOREACHBIT(mt->touches, slot)
332 			for (i = 0; i < size; i++) {
333 				dx = pt[i].x - mt->slots[slot].x;
334 				dy = pt[i].y - mt->slots[slot].y;
335 				*p++ = dx * dx + dy * dy;
336 			}
337 		m = num_touches;
338 		n = size;
339 	} else {
340 		for (i = 0; i < size; i++)
341 			FOREACHBIT(mt->touches, slot) {
342 				dx = pt[i].x - mt->slots[slot].x;
343 				dy = pt[i].y - mt->slots[slot].y;
344 				*p++ = dx * dx + dy * dy;
345 			}
346 		m = size;
347 		n = num_touches;
348 	}
349 	evdev_mt_matching(mt->matrix, m, n, p);
350 
351 	r2c = p;
352 	c2r = p + m;
353 	for (i = 0; i < m; i++)
354 		if ((j = r2c[i]) >= 0)
355 			c2r[j] = i;
356 
357 	p = (n == size ? c2r : r2c);
358 	for (i = 0; i < size; i++)
359 		if (*p++ < 0)
360 			pt[i].id = -1;
361 
362 	p = (n == size ? r2c : c2r);
363 	FOREACHBIT(mt->touches, slot)
364 		if ((i = *p++) >= 0)
365 			pt[i].id = mt->tracking_ids[slot];
366 }
367 
368 static void
369 evdev_mt_send_frame(struct evdev_dev *evdev, union evdev_mt_slot *pt, int size)
370 {
371 	struct evdev_mt *mt = evdev->ev_mt;
372 	union evdev_mt_slot *slot;
373 
374 	EVDEV_LOCK_ASSERT(evdev);
375 	MPASS(size >= 0 && size <= MAXIMAL_MT_SLOT(evdev) + 1);
376 
377 	/*
378 	 * While MT-matching assign tracking IDs of new contacts to be equal
379 	 * to a slot number to make things simpler.
380 	 */
381 	for (slot = pt; slot < pt + size; slot++) {
382 		if (slot->id < 0)
383 			slot->id = ffc_slot(evdev, mt->touches | mt->frame);
384 		if (slot->id >= 0)
385 			evdev_mt_send_slot(evdev, slot->id, slot);
386 	}
387 }
388 
389 int
390 evdev_mt_push_frame(struct evdev_dev *evdev, union evdev_mt_slot *pt, int size)
391 {
392 	if (size < 0 || size > MAXIMAL_MT_SLOT(evdev) + 1)
393 		return (EINVAL);
394 
395 	EVDEV_ENTER(evdev);
396 	evdev_mt_send_frame(evdev, pt, size);
397 	EVDEV_EXIT(evdev);
398 
399 	return (0);
400 }
401 
402 bool
403 evdev_mt_record_event(struct evdev_dev *evdev, uint16_t type, uint16_t code,
404     int32_t value)
405 {
406 	struct evdev_mt *mt = evdev->ev_mt;
407 
408 	EVDEV_LOCK_ASSERT(evdev);
409 
410 	switch (type) {
411 	case EV_SYN:
412 		if (code == SYN_MT_REPORT) {
413 			/* MT protocol type A support */
414 			KASSERT(mt->type_a, ("Not a MT type A protocol"));
415 			mt->match_frame |= 1U << mt->match_slot;
416 			mt->match_slot++;
417 			return (true);
418 		}
419 		break;
420 	case EV_ABS:
421 		if (code == ABS_MT_SLOT) {
422 			/* MT protocol type B support */
423 			KASSERT(!mt->type_a, ("Not a MT type B protocol"));
424 			KASSERT(value >= 0, ("Negative slot number"));
425 			mt->match_slot = value;
426 			mt->match_frame |= 1U << mt->match_slot;
427 			return (true);
428 		} else if (code == ABS_MT_TRACKING_ID) {
429 			KASSERT(!mt->type_a, ("Not a MT type B protocol"));
430 			if (value == -1)
431 				mt->match_frame &= ~(1U << mt->match_slot);
432 			return (true);
433 		} else if (ABS_IS_MT(code)) {
434 			KASSERT(mt->match_slot >= 0, ("Negative slot"));
435 			KASSERT(mt->match_slot <= MAXIMAL_MT_SLOT(evdev),
436 			    ("Slot number too big"));
437 			mt->match_slots[mt->match_slot].
438 			    val[ABS_MT_INDEX(code)] = value;
439 			return (true);
440 		}
441 		break;
442 	default:
443 		break;
444 	}
445 
446 	return (false);
447 }
448 
449 static void
450 evdev_mt_replay_events(struct evdev_dev *evdev)
451 {
452 	struct evdev_mt *mt = evdev->ev_mt;
453 	int slot, size = 0;
454 
455 	EVDEV_LOCK_ASSERT(evdev);
456 
457 	FOREACHBIT(mt->match_frame, slot) {
458 		if (slot != size)
459 			mt->match_slots[size] = mt->match_slots[slot];
460 		size++;
461 	}
462 	evdev_mt_match_frame(evdev, mt->match_slots, size);
463 	evdev_mt_send_frame(evdev, mt->match_slots, size);
464 	mt->match_slot = 0;
465 	mt->match_frame = 0;
466 }
467 
468 union evdev_mt_slot *
469 evdev_mt_get_match_slots(struct evdev_dev *evdev)
470 {
471 	return (evdev->ev_mt->match_slots);
472 }
473 
474 int
475 evdev_mt_get_last_slot(struct evdev_dev *evdev)
476 {
477 	return (evdev->ev_mt->last_reported_slot);
478 }
479 
480 void
481 evdev_mt_set_last_slot(struct evdev_dev *evdev, int slot)
482 {
483 	struct evdev_mt *mt = evdev->ev_mt;
484 
485 	MPASS(slot >= 0 && slot <= MAXIMAL_MT_SLOT(evdev));
486 
487 	mt->frame |= 1U << slot;
488 	mt->last_reported_slot = slot;
489 }
490 
491 int32_t
492 evdev_mt_get_value(struct evdev_dev *evdev, int slot, int16_t code)
493 {
494 	struct evdev_mt *mt = evdev->ev_mt;
495 
496 	MPASS(slot >= 0 && slot <= MAXIMAL_MT_SLOT(evdev));
497 
498 	return (mt->slots[slot].val[ABS_MT_INDEX(code)]);
499 }
500 
501 void
502 evdev_mt_set_value(struct evdev_dev *evdev, int slot, int16_t code,
503     int32_t value)
504 {
505 	struct evdev_mt *mt = evdev->ev_mt;
506 
507 	MPASS(slot >= 0 && slot <= MAXIMAL_MT_SLOT(evdev));
508 
509 	if (code == ABS_MT_TRACKING_ID) {
510 		if (value != -1)
511 			mt->touches |= 1U << slot;
512 		else
513 			mt->touches &= ~(1U << slot);
514 	}
515 	mt->slots[slot].val[ABS_MT_INDEX(code)] = value;
516 }
517 
518 int
519 evdev_mt_id_to_slot(struct evdev_dev *evdev, int32_t tracking_id)
520 {
521 	struct evdev_mt *mt = evdev->ev_mt;
522 	int slot;
523 
524 	KASSERT(!mt->type_a, ("Not a MT type B protocol"));
525 
526 	/*
527 	 * Ignore tracking_id if slot assignment is performed by evdev.
528 	 * Events are written sequentially to temporary matching buffer.
529 	 */
530 	if (bit_test(evdev->ev_flags, EVDEV_FLAG_MT_TRACK))
531 		return (ffc_slot(evdev, mt->match_frame));
532 
533 	FOREACHBIT(mt->touches, slot)
534 		if (mt->tracking_ids[slot] == tracking_id)
535 			return (slot);
536 	/*
537 	 * Do not allow allocation of new slot in a place of just
538 	 * released one within the same report.
539 	 */
540 	return (ffc_slot(evdev, mt->touches | mt->frame));
541 }
542 
543 int32_t
544 evdev_mt_reassign_id(struct evdev_dev *evdev, int slot, int32_t id)
545 {
546 	struct evdev_mt *mt = evdev->ev_mt;
547 	int32_t nid;
548 
549 	if (id == -1 || bit_test(evdev->ev_flags, EVDEV_FLAG_MT_KEEPID)) {
550 		mt->tracking_ids[slot] = id;
551 		return (id);
552 	}
553 
554 	nid = evdev_mt_get_value(evdev, slot, ABS_MT_TRACKING_ID);
555 	if (nid != -1) {
556 		KASSERT(id == mt->tracking_ids[slot],
557 		    ("MT-slot tracking id has changed"));
558 		return (nid);
559 	}
560 
561 	mt->tracking_ids[slot] = id;
562 again:
563 	nid = mt->tracking_id++;
564 	FOREACHBIT(mt->touches, slot)
565 		if (evdev_mt_get_value(evdev, slot, ABS_MT_TRACKING_ID) == nid)
566 			goto again;
567 
568 	return (nid);
569 }
570 
571 static inline int32_t
572 evdev_mt_normalize(int32_t value, int32_t mtmin, int32_t mtmax, int32_t stmax)
573 {
574 	if (stmax != 0 && mtmax != mtmin) {
575 		value = (value - mtmin) * stmax / (mtmax - mtmin);
576 		value = MAX(MIN(value, stmax), 0);
577 	}
578 	return (value);
579 }
580 
581 static void
582 evdev_mt_support_st_compat(struct evdev_dev *evdev)
583 {
584 	struct input_absinfo *ai;
585 	int i;
586 
587 	if (evdev->ev_absinfo == NULL)
588 		return;
589 
590 	evdev_support_event(evdev, EV_KEY);
591 	evdev_support_key(evdev, BTN_TOUCH);
592 
593 	/* Touchscreens should not advertise tap tool capabilities */
594 	if (!bit_test(evdev->ev_prop_flags, INPUT_PROP_DIRECT))
595 		evdev_support_nfingers(evdev, MAXIMAL_MT_SLOT(evdev) + 1);
596 
597 	/* Echo 0-th MT-slot as ST-slot */
598 	for (i = 0; i < nitems(evdev_mtstmap); i++) {
599 		if (!bit_test(evdev->ev_abs_flags, evdev_mtstmap[i].mt) ||
600 		     bit_test(evdev->ev_abs_flags, evdev_mtstmap[i].st))
601 			continue;
602 		ai = evdev->ev_absinfo + evdev_mtstmap[i].mt;
603 		evdev->ev_mt->mtst_events |= 1U << i;
604 		if (evdev_mtstmap[i].max != 0)
605 			evdev_support_abs(evdev, evdev_mtstmap[i].st,
606 			    0,
607 			    evdev_mtstmap[i].max,
608 			    0,
609 			    evdev_mt_normalize(
610 			      ai->flat, 0, ai->maximum, evdev_mtstmap[i].max),
611 			    0);
612 		else
613 			evdev_support_abs(evdev, evdev_mtstmap[i].st,
614 			    ai->minimum,
615 			    ai->maximum,
616 			    0,
617 			    ai->flat,
618 			    ai->resolution);
619 	}
620 }
621 
622 static void
623 evdev_mt_send_st_compat(struct evdev_dev *evdev)
624 {
625 	struct evdev_mt *mt = evdev->ev_mt;
626 	int nfingers, i, st_slot;
627 
628 	EVDEV_LOCK_ASSERT(evdev);
629 
630 	nfingers = bitcount(mt->touches);
631 	evdev_send_event(evdev, EV_KEY, BTN_TOUCH, nfingers > 0);
632 
633 	/* Send first active MT-slot state as single touch report */
634 	st_slot = ffs(mt->touches) - 1;
635 	if (st_slot != -1)
636 		FOREACHBIT(mt->mtst_events, i)
637 			evdev_send_event(evdev, EV_ABS, evdev_mtstmap[i].st,
638 			    evdev_mt_normalize(evdev_mt_get_value(evdev,
639 			      st_slot, evdev_mtstmap[i].mt),
640 			      evdev->ev_absinfo[evdev_mtstmap[i].mt].minimum,
641 			      evdev->ev_absinfo[evdev_mtstmap[i].mt].maximum,
642 			      evdev_mtstmap[i].max));
643 
644 	/* Touchscreens should not report tool taps */
645 	if (!bit_test(evdev->ev_prop_flags, INPUT_PROP_DIRECT))
646 		evdev_send_nfingers(evdev, nfingers);
647 
648 	if (nfingers == 0)
649 		evdev_send_event(evdev, EV_ABS, ABS_PRESSURE, 0);
650 }
651 
652 static void
653 evdev_mt_send_autorel(struct evdev_dev *evdev)
654 {
655 	struct evdev_mt *mt = evdev->ev_mt;
656 	int slot;
657 
658 	EVDEV_LOCK_ASSERT(evdev);
659 	KASSERT(mt->match_frame == 0, ("Unmatched events exist"));
660 
661 	FOREACHBIT(mt->touches & ~mt->frame, slot)
662 		evdev_mt_send_slot(evdev, slot, NULL);
663 }
664 
665 void
666 evdev_mt_push_autorel(struct evdev_dev *evdev)
667 {
668 	EVDEV_ENTER(evdev);
669 	evdev_mt_send_autorel(evdev);
670 	EVDEV_EXIT(evdev);
671 }
672