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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_flex(*mt, slots, num_slots);
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 = kzalloc_objs(*mt->red, n2);
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);