input-mt.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Input Multitouch Library
  4 *
  5 * Copyright (c) 2008-2010 Henrik Rydberg
  6 */
  7
  8#include <linux/input/mt.h>
  9#include <linux/export.h>
 10#include <linux/slab.h>
 11#include "input-core-private.h"
 12
 13#define TRKID_SGN	((TRKID_MAX + 1) >> 1)
 14
 15static void copy_abs(struct input_dev *dev, unsigned int dst, unsigned int src)
 16{
 17	if (dev->absinfo && test_bit(src, dev->absbit)) {
 18		dev->absinfo[dst] = dev->absinfo[src];
 19		dev->absinfo[dst].fuzz = 0;
 20		__set_bit(dst, dev->absbit);
 21	}
 22}
 23
 24/**
 25 * input_mt_init_slots() - initialize MT input slots
 26 * @dev: input device supporting MT events and finger tracking
 27 * @num_slots: number of slots used by the device
 28 * @flags: mt tasks to handle in core
 29 *
 30 * This function allocates all necessary memory for MT slot handling
 31 * in the input device, prepares the ABS_MT_SLOT and
 32 * ABS_MT_TRACKING_ID events for use and sets up appropriate buffers.
 33 * Depending on the flags set, it also performs pointer emulation and
 34 * frame synchronization.
 35 *
 36 * May be called repeatedly. Returns -EINVAL if attempting to
 37 * reinitialize with a different number of slots.
 38 */
 39int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots,
 40			unsigned int flags)
 41{
 42	if (!num_slots)
 43		return 0;
 44
 45	if (dev->mt)
 46		return dev->mt->num_slots != num_slots ? -EINVAL : 0;
 47
 48	/* Arbitrary limit for avoiding too large memory allocation. */
 49	if (num_slots > 1024)
 50		return -EINVAL;
 51
 52	struct input_mt *mt __free(kfree) =
 53			kzalloc(struct_size(mt, slots, num_slots), GFP_KERNEL);
 54	if (!mt)
 55		return -ENOMEM;
 56
 57	mt->num_slots = num_slots;
 58	mt->flags = flags;
 59	input_set_abs_params(dev, ABS_MT_SLOT, 0, num_slots - 1, 0, 0);
 60	input_set_abs_params(dev, ABS_MT_TRACKING_ID, 0, TRKID_MAX, 0, 0);
 61
 62	if (flags & (INPUT_MT_POINTER | INPUT_MT_DIRECT)) {
 63		__set_bit(EV_KEY, dev->evbit);
 64		__set_bit(BTN_TOUCH, dev->keybit);
 65
 66		copy_abs(dev, ABS_X, ABS_MT_POSITION_X);
 67		copy_abs(dev, ABS_Y, ABS_MT_POSITION_Y);
 68		copy_abs(dev, ABS_PRESSURE, ABS_MT_PRESSURE);
 69	}
 70	if (flags & INPUT_MT_POINTER) {
 71		__set_bit(BTN_TOOL_FINGER, dev->keybit);
 72		__set_bit(BTN_TOOL_DOUBLETAP, dev->keybit);
 73		if (num_slots >= 3)
 74			__set_bit(BTN_TOOL_TRIPLETAP, dev->keybit);
 75		if (num_slots >= 4)
 76			__set_bit(BTN_TOOL_QUADTAP, dev->keybit);
 77		if (num_slots >= 5)
 78			__set_bit(BTN_TOOL_QUINTTAP, dev->keybit);
 79		__set_bit(INPUT_PROP_POINTER, dev->propbit);
 80	}
 81	if (flags & INPUT_MT_DIRECT)
 82		__set_bit(INPUT_PROP_DIRECT, dev->propbit);
 83	if (flags & INPUT_MT_SEMI_MT)
 84		__set_bit(INPUT_PROP_SEMI_MT, dev->propbit);
 85	if (flags & INPUT_MT_TRACK) {
 86		unsigned int n2 = num_slots * num_slots;
 87		mt->red = kcalloc(n2, sizeof(*mt->red), GFP_KERNEL);
 88		if (!mt->red)
 89			return -ENOMEM;
 90	}
 91
 92	/* Mark slots as 'inactive' */
 93	for (unsigned int i = 0; i < num_slots; i++)
 94		input_mt_set_value(&mt->slots[i], ABS_MT_TRACKING_ID, -1);
 95
 96	/* Mark slots as 'unused' */
 97	mt->frame = 1;
 98
 99	dev->mt = no_free_ptr(mt);
100	return 0;
101}
102EXPORT_SYMBOL(input_mt_init_slots);
103
104/**
105 * input_mt_destroy_slots() - frees the MT slots of the input device
106 * @dev: input device with allocated MT slots
107 *
108 * This function is only needed in error path as the input core will
109 * automatically free the MT slots when the device is destroyed.
110 */
111void input_mt_destroy_slots(struct input_dev *dev)
112{
113	if (dev->mt) {
114		kfree(dev->mt->red);
115		kfree(dev->mt);
116	}
117	dev->mt = NULL;
118}
119EXPORT_SYMBOL(input_mt_destroy_slots);
120
121/**
122 * input_mt_report_slot_state() - report contact state
123 * @dev: input device with allocated MT slots
124 * @tool_type: the tool type to use in this slot
125 * @active: true if contact is active, false otherwise
126 *
127 * Reports a contact via ABS_MT_TRACKING_ID, and optionally
128 * ABS_MT_TOOL_TYPE. If active is true and the slot is currently
129 * inactive, or if the tool type is changed, a new tracking id is
130 * assigned to the slot. The tool type is only reported if the
131 * corresponding absbit field is set.
132 *
133 * Returns true if contact is active.
134 */
135bool input_mt_report_slot_state(struct input_dev *dev,
136				unsigned int tool_type, bool active)
137{
138	struct input_mt *mt = dev->mt;
139	struct input_mt_slot *slot;
140	int id;
141
142	if (!mt)
143		return false;
144
145	slot = &mt->slots[mt->slot];
146	slot->frame = mt->frame;
147
148	if (!active) {
149		input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
150		return false;
151	}
152
153	id = input_mt_get_value(slot, ABS_MT_TRACKING_ID);
154	if (id < 0)
155		id = input_mt_new_trkid(mt);
156
157	input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, id);
158	input_event(dev, EV_ABS, ABS_MT_TOOL_TYPE, tool_type);
159
160	return true;
161}
162EXPORT_SYMBOL(input_mt_report_slot_state);
163
164/**
165 * input_mt_report_finger_count() - report contact count
166 * @dev: input device with allocated MT slots
167 * @count: the number of contacts
168 *
169 * Reports the contact count via BTN_TOOL_FINGER, BTN_TOOL_DOUBLETAP,
170 * BTN_TOOL_TRIPLETAP and BTN_TOOL_QUADTAP.
171 *
172 * The input core ensures only the KEY events already setup for
173 * this device will produce output.
174 */
175void input_mt_report_finger_count(struct input_dev *dev, int count)
176{
177	input_event(dev, EV_KEY, BTN_TOOL_FINGER, count == 1);
178	input_event(dev, EV_KEY, BTN_TOOL_DOUBLETAP, count == 2);
179	input_event(dev, EV_KEY, BTN_TOOL_TRIPLETAP, count == 3);
180	input_event(dev, EV_KEY, BTN_TOOL_QUADTAP, count == 4);
181	input_event(dev, EV_KEY, BTN_TOOL_QUINTTAP, count == 5);
182}
183EXPORT_SYMBOL(input_mt_report_finger_count);
184
185/**
186 * input_mt_report_pointer_emulation() - common pointer emulation
187 * @dev: input device with allocated MT slots
188 * @use_count: report number of active contacts as finger count
189 *
190 * Performs legacy pointer emulation via BTN_TOUCH, ABS_X, ABS_Y and
191 * ABS_PRESSURE. Touchpad finger count is emulated if use_count is true.
192 *
193 * The input core ensures only the KEY and ABS axes already setup for
194 * this device will produce output.
195 */
196void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)
197{
198	struct input_mt *mt = dev->mt;
199	struct input_mt_slot *oldest;
200	int oldid, count, i;
201	int p, reported_p = 0;
202
203	if (!mt)
204		return;
205
206	oldest = NULL;
207	oldid = mt->trkid;
208	count = 0;
209
210	for (i = 0; i < mt->num_slots; ++i) {
211		struct input_mt_slot *ps = &mt->slots[i];
212		int id = input_mt_get_value(ps, ABS_MT_TRACKING_ID);
213
214		if (id < 0)
215			continue;
216		if ((id - oldid) & TRKID_SGN) {
217			oldest = ps;
218			oldid = id;
219		}
220		if (test_bit(ABS_MT_PRESSURE, dev->absbit)) {
221			p = input_mt_get_value(ps, ABS_MT_PRESSURE);
222			if (mt->flags & INPUT_MT_TOTAL_FORCE)
223				reported_p += p;
224			else if (oldid == id)
225				reported_p = p;
226		}
227		count++;
228	}
229
230	input_event(dev, EV_KEY, BTN_TOUCH, count > 0);
231
232	if (use_count) {
233		if (count == 0 &&
234		    !test_bit(ABS_MT_DISTANCE, dev->absbit) &&
235		    test_bit(ABS_DISTANCE, dev->absbit) &&
236		    input_abs_get_val(dev, ABS_DISTANCE) != 0) {
237			/*
238			 * Force reporting BTN_TOOL_FINGER for devices that
239			 * only report general hover (and not per-contact
240			 * distance) when contact is in proximity but not
241			 * on the surface.
242			 */
243			count = 1;
244		}
245
246		input_mt_report_finger_count(dev, count);
247	}
248
249	if (oldest) {
250		int x = input_mt_get_value(oldest, ABS_MT_POSITION_X);
251		int y = input_mt_get_value(oldest, ABS_MT_POSITION_Y);
252
253		input_event(dev, EV_ABS, ABS_X, x);
254		input_event(dev, EV_ABS, ABS_Y, y);
255
256		if (test_bit(ABS_MT_PRESSURE, dev->absbit))
257			input_event(dev, EV_ABS, ABS_PRESSURE, reported_p);
258	} else {
259		if (test_bit(ABS_MT_PRESSURE, dev->absbit))
260			input_event(dev, EV_ABS, ABS_PRESSURE, 0);
261	}
262}
263EXPORT_SYMBOL(input_mt_report_pointer_emulation);
264
265static void __input_mt_drop_unused(struct input_dev *dev, struct input_mt *mt)
266{
267	int i;
268
269	lockdep_assert_held(&dev->event_lock);
270
271	for (i = 0; i < mt->num_slots; i++) {
272		if (input_mt_is_active(&mt->slots[i]) &&
273		    !input_mt_is_used(mt, &mt->slots[i])) {
274			input_handle_event(dev, EV_ABS, ABS_MT_SLOT, i);
275			input_handle_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
276		}
277	}
278}
279
280/**
281 * input_mt_drop_unused() - Inactivate slots not seen in this frame
282 * @dev: input device with allocated MT slots
283 *
284 * Lift all slots not seen since the last call to this function.
285 */
286void input_mt_drop_unused(struct input_dev *dev)
287{
288	struct input_mt *mt = dev->mt;
289
290	if (mt) {
291		guard(spinlock_irqsave)(&dev->event_lock);
292
293		__input_mt_drop_unused(dev, mt);
294		mt->frame++;
295	}
296}
297EXPORT_SYMBOL(input_mt_drop_unused);
298
299/**
300 * input_mt_release_slots() - Deactivate all slots
301 * @dev: input device with allocated MT slots
302 *
303 * Lift all active slots.
304 */
305void input_mt_release_slots(struct input_dev *dev)
306{
307	struct input_mt *mt = dev->mt;
308
309	lockdep_assert_held(&dev->event_lock);
310
311	if (mt) {
312		/* This will effectively mark all slots unused. */
313		mt->frame++;
314
315		__input_mt_drop_unused(dev, mt);
316
317		if (test_bit(ABS_PRESSURE, dev->absbit))
318			input_handle_event(dev, EV_ABS, ABS_PRESSURE, 0);
319
320		mt->frame++;
321	}
322}
323
324/**
325 * input_mt_sync_frame() - synchronize mt frame
326 * @dev: input device with allocated MT slots
327 *
328 * Close the frame and prepare the internal state for a new one.
329 * Depending on the flags, marks unused slots as inactive and performs
330 * pointer emulation.
331 */
332void input_mt_sync_frame(struct input_dev *dev)
333{
334	struct input_mt *mt = dev->mt;
335	bool use_count = false;
336
337	if (!mt)
338		return;
339
340	if (mt->flags & INPUT_MT_DROP_UNUSED) {
341		guard(spinlock_irqsave)(&dev->event_lock);
342		__input_mt_drop_unused(dev, mt);
343	}
344
345	if ((mt->flags & INPUT_MT_POINTER) && !(mt->flags & INPUT_MT_SEMI_MT))
346		use_count = true;
347
348	input_mt_report_pointer_emulation(dev, use_count);
349
350	mt->frame++;
351}
352EXPORT_SYMBOL(input_mt_sync_frame);
353
354static int adjust_dual(int *begin, int step, int *end, int eq, int mu)
355{
356	int f, *p, s, c;
357
358	if (begin == end)
359		return 0;
360
361	f = *begin;
362	p = begin + step;
363	s = p == end ? f + 1 : *p;
364
365	for (; p != end; p += step) {
366		if (*p < f) {
367			s = f;
368			f = *p;
369		} else if (*p < s) {
370			s = *p;
371		}
372	}
373
374	c = (f + s + 1) / 2;
375	if (c == 0 || (c > mu && (!eq || mu > 0)))
376		return 0;
377	/* Improve convergence for positive matrices by penalizing overcovers */
378	if (s < 0 && mu <= 0)
379		c *= 2;
380
381	for (p = begin; p != end; p += step)
382		*p -= c;
383
384	return (c < s && s <= 0) || (f >= 0 && f < c);
385}
386
387static void find_reduced_matrix(int *w, int nr, int nc, int nrc, int mu)
388{
389	int i, k, sum;
390
391	for (k = 0; k < nrc; k++) {
392		for (i = 0; i < nr; i++)
393			adjust_dual(w + i, nr, w + i + nrc, nr <= nc, mu);
394		sum = 0;
395		for (i = 0; i < nrc; i += nr)
396			sum += adjust_dual(w + i, 1, w + i + nr, nc <= nr, mu);
397		if (!sum)
398			break;
399	}
400}
401
402static int input_mt_set_matrix(struct input_mt *mt,
403			       const struct input_mt_pos *pos, int num_pos,
404			       int mu)
405{
406	const struct input_mt_pos *p;
407	struct input_mt_slot *s;
408	int *w = mt->red;
409	int x, y;
410
411	for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
412		if (!input_mt_is_active(s))
413			continue;
414		x = input_mt_get_value(s, ABS_MT_POSITION_X);
415		y = input_mt_get_value(s, ABS_MT_POSITION_Y);
416		for (p = pos; p != pos + num_pos; p++) {
417			int dx = x - p->x, dy = y - p->y;
418			*w++ = dx * dx + dy * dy - mu;
419		}
420	}
421
422	return w - mt->red;
423}
424
425static void input_mt_set_slots(struct input_mt *mt,
426			       int *slots, int num_pos)
427{
428	struct input_mt_slot *s;
429	int *w = mt->red, j;
430
431	for (j = 0; j != num_pos; j++)
432		slots[j] = -1;
433
434	for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
435		if (!input_mt_is_active(s))
436			continue;
437
438		for (j = 0; j != num_pos; j++) {
439			if (w[j] < 0) {
440				slots[j] = s - mt->slots;
441				break;
442			}
443		}
444
445		w += num_pos;
446	}
447
448	for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
449		if (input_mt_is_active(s))
450			continue;
451
452		for (j = 0; j != num_pos; j++) {
453			if (slots[j] < 0) {
454				slots[j] = s - mt->slots;
455				break;
456			}
457		}
458	}
459}
460
461/**
462 * input_mt_assign_slots() - perform a best-match assignment
463 * @dev: input device with allocated MT slots
464 * @slots: the slot assignment to be filled
465 * @pos: the position array to match
466 * @num_pos: number of positions
467 * @dmax: maximum ABS_MT_POSITION displacement (zero for infinite)
468 *
469 * Performs a best match against the current contacts and returns
470 * the slot assignment list. New contacts are assigned to unused
471 * slots.
472 *
473 * The assignments are balanced so that all coordinate displacements are
474 * below the euclidian distance dmax. If no such assignment can be found,
475 * some contacts are assigned to unused slots.
476 *
477 * Returns zero on success, or negative error in case of failure.
478 */
479int input_mt_assign_slots(struct input_dev *dev, int *slots,
480			  const struct input_mt_pos *pos, int num_pos,
481			  int dmax)
482{
483	struct input_mt *mt = dev->mt;
484	int mu = 2 * dmax * dmax;
485	int nrc;
486
487	if (!mt || !mt->red)
488		return -ENXIO;
489	if (num_pos > mt->num_slots)
490		return -EINVAL;
491	if (num_pos < 1)
492		return 0;
493
494	nrc = input_mt_set_matrix(mt, pos, num_pos, mu);
495	find_reduced_matrix(mt->red, num_pos, nrc / num_pos, nrc, mu);
496	input_mt_set_slots(mt, slots, num_pos);
497
498	return 0;
499}
500EXPORT_SYMBOL(input_mt_assign_slots);
501
502/**
503 * input_mt_get_slot_by_key() - return slot matching key
504 * @dev: input device with allocated MT slots
505 * @key: the key of the sought slot
506 *
507 * Returns the slot of the given key, if it exists, otherwise
508 * set the key on the first unused slot and return.
509 *
510 * If no available slot can be found, -1 is returned.
511 * Note that for this function to work properly, input_mt_sync_frame() has
512 * to be called at each frame.
513 */
514int input_mt_get_slot_by_key(struct input_dev *dev, int key)
515{
516	struct input_mt *mt = dev->mt;
517	struct input_mt_slot *s;
518
519	if (!mt)
520		return -1;
521
522	for (s = mt->slots; s != mt->slots + mt->num_slots; s++)
523		if (input_mt_is_active(s) && s->key == key)
524			return s - mt->slots;
525
526	for (s = mt->slots; s != mt->slots + mt->num_slots; s++)
527		if (!input_mt_is_active(s) && !input_mt_is_used(mt, s)) {
528			s->key = key;
529			return s - mt->slots;
530		}
531
532	return -1;
533}
534EXPORT_SYMBOL(input_mt_get_slot_by_key);