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1/*
2 * Input Multitouch Library
3 *
4 * Copyright (c) 2008-2010 Henrik Rydberg
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 as published by
8 * the Free Software Foundation.
9 */
10
11#include <linux/input/mt.h>
12#include <linux/slab.h>
13
14#define TRKID_SGN ((TRKID_MAX + 1) >> 1)
15
16/**
17 * input_mt_init_slots() - initialize MT input slots
18 * @dev: input device supporting MT events and finger tracking
19 * @num_slots: number of slots used by the device
20 *
21 * This function allocates all necessary memory for MT slot handling
22 * in the input device, prepares the ABS_MT_SLOT and
23 * ABS_MT_TRACKING_ID events for use and sets up appropriate buffers.
24 * May be called repeatedly. Returns -EINVAL if attempting to
25 * reinitialize with a different number of slots.
26 */
27int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots)
28{
29 int i;
30
31 if (!num_slots)
32 return 0;
33 if (dev->mt)
34 return dev->mtsize != num_slots ? -EINVAL : 0;
35
36 dev->mt = kcalloc(num_slots, sizeof(struct input_mt_slot), GFP_KERNEL);
37 if (!dev->mt)
38 return -ENOMEM;
39
40 dev->mtsize = num_slots;
41 input_set_abs_params(dev, ABS_MT_SLOT, 0, num_slots - 1, 0, 0);
42 input_set_abs_params(dev, ABS_MT_TRACKING_ID, 0, TRKID_MAX, 0, 0);
43 input_set_events_per_packet(dev, 6 * num_slots);
44
45 /* Mark slots as 'unused' */
46 for (i = 0; i < num_slots; i++)
47 input_mt_set_value(&dev->mt[i], ABS_MT_TRACKING_ID, -1);
48
49 return 0;
50}
51EXPORT_SYMBOL(input_mt_init_slots);
52
53/**
54 * input_mt_destroy_slots() - frees the MT slots of the input device
55 * @dev: input device with allocated MT slots
56 *
57 * This function is only needed in error path as the input core will
58 * automatically free the MT slots when the device is destroyed.
59 */
60void input_mt_destroy_slots(struct input_dev *dev)
61{
62 kfree(dev->mt);
63 dev->mt = NULL;
64 dev->mtsize = 0;
65 dev->slot = 0;
66 dev->trkid = 0;
67}
68EXPORT_SYMBOL(input_mt_destroy_slots);
69
70/**
71 * input_mt_report_slot_state() - report contact state
72 * @dev: input device with allocated MT slots
73 * @tool_type: the tool type to use in this slot
74 * @active: true if contact is active, false otherwise
75 *
76 * Reports a contact via ABS_MT_TRACKING_ID, and optionally
77 * ABS_MT_TOOL_TYPE. If active is true and the slot is currently
78 * inactive, or if the tool type is changed, a new tracking id is
79 * assigned to the slot. The tool type is only reported if the
80 * corresponding absbit field is set.
81 */
82void input_mt_report_slot_state(struct input_dev *dev,
83 unsigned int tool_type, bool active)
84{
85 struct input_mt_slot *mt;
86 int id;
87
88 if (!dev->mt || !active) {
89 input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
90 return;
91 }
92
93 mt = &dev->mt[dev->slot];
94 id = input_mt_get_value(mt, ABS_MT_TRACKING_ID);
95 if (id < 0 || input_mt_get_value(mt, ABS_MT_TOOL_TYPE) != tool_type)
96 id = input_mt_new_trkid(dev);
97
98 input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, id);
99 input_event(dev, EV_ABS, ABS_MT_TOOL_TYPE, tool_type);
100}
101EXPORT_SYMBOL(input_mt_report_slot_state);
102
103/**
104 * input_mt_report_finger_count() - report contact count
105 * @dev: input device with allocated MT slots
106 * @count: the number of contacts
107 *
108 * Reports the contact count via BTN_TOOL_FINGER, BTN_TOOL_DOUBLETAP,
109 * BTN_TOOL_TRIPLETAP and BTN_TOOL_QUADTAP.
110 *
111 * The input core ensures only the KEY events already setup for
112 * this device will produce output.
113 */
114void input_mt_report_finger_count(struct input_dev *dev, int count)
115{
116 input_event(dev, EV_KEY, BTN_TOOL_FINGER, count == 1);
117 input_event(dev, EV_KEY, BTN_TOOL_DOUBLETAP, count == 2);
118 input_event(dev, EV_KEY, BTN_TOOL_TRIPLETAP, count == 3);
119 input_event(dev, EV_KEY, BTN_TOOL_QUADTAP, count == 4);
120}
121EXPORT_SYMBOL(input_mt_report_finger_count);
122
123/**
124 * input_mt_report_pointer_emulation() - common pointer emulation
125 * @dev: input device with allocated MT slots
126 * @use_count: report number of active contacts as finger count
127 *
128 * Performs legacy pointer emulation via BTN_TOUCH, ABS_X, ABS_Y and
129 * ABS_PRESSURE. Touchpad finger count is emulated if use_count is true.
130 *
131 * The input core ensures only the KEY and ABS axes already setup for
132 * this device will produce output.
133 */
134void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)
135{
136 struct input_mt_slot *oldest = 0;
137 int oldid = dev->trkid;
138 int count = 0;
139 int i;
140
141 for (i = 0; i < dev->mtsize; ++i) {
142 struct input_mt_slot *ps = &dev->mt[i];
143 int id = input_mt_get_value(ps, ABS_MT_TRACKING_ID);
144
145 if (id < 0)
146 continue;
147 if ((id - oldid) & TRKID_SGN) {
148 oldest = ps;
149 oldid = id;
150 }
151 count++;
152 }
153
154 input_event(dev, EV_KEY, BTN_TOUCH, count > 0);
155 if (use_count)
156 input_mt_report_finger_count(dev, count);
157
158 if (oldest) {
159 int x = input_mt_get_value(oldest, ABS_MT_POSITION_X);
160 int y = input_mt_get_value(oldest, ABS_MT_POSITION_Y);
161 int p = input_mt_get_value(oldest, ABS_MT_PRESSURE);
162
163 input_event(dev, EV_ABS, ABS_X, x);
164 input_event(dev, EV_ABS, ABS_Y, y);
165 input_event(dev, EV_ABS, ABS_PRESSURE, p);
166 } else {
167 input_event(dev, EV_ABS, ABS_PRESSURE, 0);
168 }
169}
170EXPORT_SYMBOL(input_mt_report_pointer_emulation);
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 struct input_mt *mt = dev->mt;
43 int i;
44
45 if (!num_slots)
46 return 0;
47 if (mt)
48 return mt->num_slots != num_slots ? -EINVAL : 0;
49 /* Arbitrary limit for avoiding too large memory allocation. */
50 if (num_slots > 1024)
51 return -EINVAL;
52
53 mt = kzalloc(struct_size(mt, slots, num_slots), GFP_KERNEL);
54 if (!mt)
55 goto err_mem;
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 goto err_mem;
90 }
91
92 /* Mark slots as 'inactive' */
93 for (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 = mt;
100 return 0;
101err_mem:
102 kfree(mt);
103 return -ENOMEM;
104}
105EXPORT_SYMBOL(input_mt_init_slots);
106
107/**
108 * input_mt_destroy_slots() - frees the MT slots of the input device
109 * @dev: input device with allocated MT slots
110 *
111 * This function is only needed in error path as the input core will
112 * automatically free the MT slots when the device is destroyed.
113 */
114void input_mt_destroy_slots(struct input_dev *dev)
115{
116 if (dev->mt) {
117 kfree(dev->mt->red);
118 kfree(dev->mt);
119 }
120 dev->mt = NULL;
121}
122EXPORT_SYMBOL(input_mt_destroy_slots);
123
124/**
125 * input_mt_report_slot_state() - report contact state
126 * @dev: input device with allocated MT slots
127 * @tool_type: the tool type to use in this slot
128 * @active: true if contact is active, false otherwise
129 *
130 * Reports a contact via ABS_MT_TRACKING_ID, and optionally
131 * ABS_MT_TOOL_TYPE. If active is true and the slot is currently
132 * inactive, or if the tool type is changed, a new tracking id is
133 * assigned to the slot. The tool type is only reported if the
134 * corresponding absbit field is set.
135 *
136 * Returns true if contact is active.
137 */
138bool input_mt_report_slot_state(struct input_dev *dev,
139 unsigned int tool_type, bool active)
140{
141 struct input_mt *mt = dev->mt;
142 struct input_mt_slot *slot;
143 int id;
144
145 if (!mt)
146 return false;
147
148 slot = &mt->slots[mt->slot];
149 slot->frame = mt->frame;
150
151 if (!active) {
152 input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
153 return false;
154 }
155
156 id = input_mt_get_value(slot, ABS_MT_TRACKING_ID);
157 if (id < 0)
158 id = input_mt_new_trkid(mt);
159
160 input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, id);
161 input_event(dev, EV_ABS, ABS_MT_TOOL_TYPE, tool_type);
162
163 return true;
164}
165EXPORT_SYMBOL(input_mt_report_slot_state);
166
167/**
168 * input_mt_report_finger_count() - report contact count
169 * @dev: input device with allocated MT slots
170 * @count: the number of contacts
171 *
172 * Reports the contact count via BTN_TOOL_FINGER, BTN_TOOL_DOUBLETAP,
173 * BTN_TOOL_TRIPLETAP and BTN_TOOL_QUADTAP.
174 *
175 * The input core ensures only the KEY events already setup for
176 * this device will produce output.
177 */
178void input_mt_report_finger_count(struct input_dev *dev, int count)
179{
180 input_event(dev, EV_KEY, BTN_TOOL_FINGER, count == 1);
181 input_event(dev, EV_KEY, BTN_TOOL_DOUBLETAP, count == 2);
182 input_event(dev, EV_KEY, BTN_TOOL_TRIPLETAP, count == 3);
183 input_event(dev, EV_KEY, BTN_TOOL_QUADTAP, count == 4);
184 input_event(dev, EV_KEY, BTN_TOOL_QUINTTAP, count == 5);
185}
186EXPORT_SYMBOL(input_mt_report_finger_count);
187
188/**
189 * input_mt_report_pointer_emulation() - common pointer emulation
190 * @dev: input device with allocated MT slots
191 * @use_count: report number of active contacts as finger count
192 *
193 * Performs legacy pointer emulation via BTN_TOUCH, ABS_X, ABS_Y and
194 * ABS_PRESSURE. Touchpad finger count is emulated if use_count is true.
195 *
196 * The input core ensures only the KEY and ABS axes already setup for
197 * this device will produce output.
198 */
199void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)
200{
201 struct input_mt *mt = dev->mt;
202 struct input_mt_slot *oldest;
203 int oldid, count, i;
204
205 if (!mt)
206 return;
207
208 oldest = NULL;
209 oldid = mt->trkid;
210 count = 0;
211
212 for (i = 0; i < mt->num_slots; ++i) {
213 struct input_mt_slot *ps = &mt->slots[i];
214 int id = input_mt_get_value(ps, ABS_MT_TRACKING_ID);
215
216 if (id < 0)
217 continue;
218 if ((id - oldid) & TRKID_SGN) {
219 oldest = ps;
220 oldid = id;
221 }
222 count++;
223 }
224
225 input_event(dev, EV_KEY, BTN_TOUCH, count > 0);
226
227 if (use_count) {
228 if (count == 0 &&
229 !test_bit(ABS_MT_DISTANCE, dev->absbit) &&
230 test_bit(ABS_DISTANCE, dev->absbit) &&
231 input_abs_get_val(dev, ABS_DISTANCE) != 0) {
232 /*
233 * Force reporting BTN_TOOL_FINGER for devices that
234 * only report general hover (and not per-contact
235 * distance) when contact is in proximity but not
236 * on the surface.
237 */
238 count = 1;
239 }
240
241 input_mt_report_finger_count(dev, count);
242 }
243
244 if (oldest) {
245 int x = input_mt_get_value(oldest, ABS_MT_POSITION_X);
246 int y = input_mt_get_value(oldest, ABS_MT_POSITION_Y);
247
248 input_event(dev, EV_ABS, ABS_X, x);
249 input_event(dev, EV_ABS, ABS_Y, y);
250
251 if (test_bit(ABS_MT_PRESSURE, dev->absbit)) {
252 int p = input_mt_get_value(oldest, ABS_MT_PRESSURE);
253 input_event(dev, EV_ABS, ABS_PRESSURE, p);
254 }
255 } else {
256 if (test_bit(ABS_MT_PRESSURE, dev->absbit))
257 input_event(dev, EV_ABS, ABS_PRESSURE, 0);
258 }
259}
260EXPORT_SYMBOL(input_mt_report_pointer_emulation);
261
262static void __input_mt_drop_unused(struct input_dev *dev, struct input_mt *mt)
263{
264 int i;
265
266 lockdep_assert_held(&dev->event_lock);
267
268 for (i = 0; i < mt->num_slots; i++) {
269 if (input_mt_is_active(&mt->slots[i]) &&
270 !input_mt_is_used(mt, &mt->slots[i])) {
271 input_handle_event(dev, EV_ABS, ABS_MT_SLOT, i);
272 input_handle_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
273 }
274 }
275}
276
277/**
278 * input_mt_drop_unused() - Inactivate slots not seen in this frame
279 * @dev: input device with allocated MT slots
280 *
281 * Lift all slots not seen since the last call to this function.
282 */
283void input_mt_drop_unused(struct input_dev *dev)
284{
285 struct input_mt *mt = dev->mt;
286
287 if (mt) {
288 unsigned long flags;
289
290 spin_lock_irqsave(&dev->event_lock, flags);
291
292 __input_mt_drop_unused(dev, mt);
293 mt->frame++;
294
295 spin_unlock_irqrestore(&dev->event_lock, flags);
296 }
297}
298EXPORT_SYMBOL(input_mt_drop_unused);
299
300/**
301 * input_mt_release_slots() - Deactivate all slots
302 * @dev: input device with allocated MT slots
303 *
304 * Lift all active slots.
305 */
306void input_mt_release_slots(struct input_dev *dev)
307{
308 struct input_mt *mt = dev->mt;
309
310 lockdep_assert_held(&dev->event_lock);
311
312 if (mt) {
313 /* This will effectively mark all slots unused. */
314 mt->frame++;
315
316 __input_mt_drop_unused(dev, mt);
317
318 if (test_bit(ABS_PRESSURE, dev->absbit))
319 input_handle_event(dev, EV_ABS, ABS_PRESSURE, 0);
320
321 mt->frame++;
322 }
323}
324
325/**
326 * input_mt_sync_frame() - synchronize mt frame
327 * @dev: input device with allocated MT slots
328 *
329 * Close the frame and prepare the internal state for a new one.
330 * Depending on the flags, marks unused slots as inactive and performs
331 * pointer emulation.
332 */
333void input_mt_sync_frame(struct input_dev *dev)
334{
335 struct input_mt *mt = dev->mt;
336 bool use_count = false;
337
338 if (!mt)
339 return;
340
341 if (mt->flags & INPUT_MT_DROP_UNUSED) {
342 unsigned long flags;
343
344 spin_lock_irqsave(&dev->event_lock, flags);
345 __input_mt_drop_unused(dev, mt);
346 spin_unlock_irqrestore(&dev->event_lock, flags);
347 }
348
349 if ((mt->flags & INPUT_MT_POINTER) && !(mt->flags & INPUT_MT_SEMI_MT))
350 use_count = true;
351
352 input_mt_report_pointer_emulation(dev, use_count);
353
354 mt->frame++;
355}
356EXPORT_SYMBOL(input_mt_sync_frame);
357
358static int adjust_dual(int *begin, int step, int *end, int eq, int mu)
359{
360 int f, *p, s, c;
361
362 if (begin == end)
363 return 0;
364
365 f = *begin;
366 p = begin + step;
367 s = p == end ? f + 1 : *p;
368
369 for (; p != end; p += step) {
370 if (*p < f) {
371 s = f;
372 f = *p;
373 } else if (*p < s) {
374 s = *p;
375 }
376 }
377
378 c = (f + s + 1) / 2;
379 if (c == 0 || (c > mu && (!eq || mu > 0)))
380 return 0;
381 /* Improve convergence for positive matrices by penalizing overcovers */
382 if (s < 0 && mu <= 0)
383 c *= 2;
384
385 for (p = begin; p != end; p += step)
386 *p -= c;
387
388 return (c < s && s <= 0) || (f >= 0 && f < c);
389}
390
391static void find_reduced_matrix(int *w, int nr, int nc, int nrc, int mu)
392{
393 int i, k, sum;
394
395 for (k = 0; k < nrc; k++) {
396 for (i = 0; i < nr; i++)
397 adjust_dual(w + i, nr, w + i + nrc, nr <= nc, mu);
398 sum = 0;
399 for (i = 0; i < nrc; i += nr)
400 sum += adjust_dual(w + i, 1, w + i + nr, nc <= nr, mu);
401 if (!sum)
402 break;
403 }
404}
405
406static int input_mt_set_matrix(struct input_mt *mt,
407 const struct input_mt_pos *pos, int num_pos,
408 int mu)
409{
410 const struct input_mt_pos *p;
411 struct input_mt_slot *s;
412 int *w = mt->red;
413 int x, y;
414
415 for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
416 if (!input_mt_is_active(s))
417 continue;
418 x = input_mt_get_value(s, ABS_MT_POSITION_X);
419 y = input_mt_get_value(s, ABS_MT_POSITION_Y);
420 for (p = pos; p != pos + num_pos; p++) {
421 int dx = x - p->x, dy = y - p->y;
422 *w++ = dx * dx + dy * dy - mu;
423 }
424 }
425
426 return w - mt->red;
427}
428
429static void input_mt_set_slots(struct input_mt *mt,
430 int *slots, int num_pos)
431{
432 struct input_mt_slot *s;
433 int *w = mt->red, j;
434
435 for (j = 0; j != num_pos; j++)
436 slots[j] = -1;
437
438 for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
439 if (!input_mt_is_active(s))
440 continue;
441
442 for (j = 0; j != num_pos; j++) {
443 if (w[j] < 0) {
444 slots[j] = s - mt->slots;
445 break;
446 }
447 }
448
449 w += num_pos;
450 }
451
452 for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
453 if (input_mt_is_active(s))
454 continue;
455
456 for (j = 0; j != num_pos; j++) {
457 if (slots[j] < 0) {
458 slots[j] = s - mt->slots;
459 break;
460 }
461 }
462 }
463}
464
465/**
466 * input_mt_assign_slots() - perform a best-match assignment
467 * @dev: input device with allocated MT slots
468 * @slots: the slot assignment to be filled
469 * @pos: the position array to match
470 * @num_pos: number of positions
471 * @dmax: maximum ABS_MT_POSITION displacement (zero for infinite)
472 *
473 * Performs a best match against the current contacts and returns
474 * the slot assignment list. New contacts are assigned to unused
475 * slots.
476 *
477 * The assignments are balanced so that all coordinate displacements are
478 * below the euclidian distance dmax. If no such assignment can be found,
479 * some contacts are assigned to unused slots.
480 *
481 * Returns zero on success, or negative error in case of failure.
482 */
483int input_mt_assign_slots(struct input_dev *dev, int *slots,
484 const struct input_mt_pos *pos, int num_pos,
485 int dmax)
486{
487 struct input_mt *mt = dev->mt;
488 int mu = 2 * dmax * dmax;
489 int nrc;
490
491 if (!mt || !mt->red)
492 return -ENXIO;
493 if (num_pos > mt->num_slots)
494 return -EINVAL;
495 if (num_pos < 1)
496 return 0;
497
498 nrc = input_mt_set_matrix(mt, pos, num_pos, mu);
499 find_reduced_matrix(mt->red, num_pos, nrc / num_pos, nrc, mu);
500 input_mt_set_slots(mt, slots, num_pos);
501
502 return 0;
503}
504EXPORT_SYMBOL(input_mt_assign_slots);
505
506/**
507 * input_mt_get_slot_by_key() - return slot matching key
508 * @dev: input device with allocated MT slots
509 * @key: the key of the sought slot
510 *
511 * Returns the slot of the given key, if it exists, otherwise
512 * set the key on the first unused slot and return.
513 *
514 * If no available slot can be found, -1 is returned.
515 * Note that for this function to work properly, input_mt_sync_frame() has
516 * to be called at each frame.
517 */
518int input_mt_get_slot_by_key(struct input_dev *dev, int key)
519{
520 struct input_mt *mt = dev->mt;
521 struct input_mt_slot *s;
522
523 if (!mt)
524 return -1;
525
526 for (s = mt->slots; s != mt->slots + mt->num_slots; s++)
527 if (input_mt_is_active(s) && s->key == key)
528 return s - mt->slots;
529
530 for (s = mt->slots; s != mt->slots + mt->num_slots; s++)
531 if (!input_mt_is_active(s) && !input_mt_is_used(mt, s)) {
532 s->key = key;
533 return s - mt->slots;
534 }
535
536 return -1;
537}
538EXPORT_SYMBOL(input_mt_get_slot_by_key);