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Henrik Rydberg47c78e82010-11-27 09:16:48 +01001/*
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>
Paul Gortmaker15d05802011-10-25 14:51:47 -040012#include <linux/export.h>
Henrik Rydberg47c78e82010-11-27 09:16:48 +010013#include <linux/slab.h>
14
Henrik Rydbergc5f4dec2010-12-15 13:50:34 +010015#define TRKID_SGN ((TRKID_MAX + 1) >> 1)
16
Henrik Rydberg55e49082012-08-22 20:43:22 +020017static void copy_abs(struct input_dev *dev, unsigned int dst, unsigned int src)
18{
19 if (dev->absinfo && test_bit(src, dev->absbit)) {
20 dev->absinfo[dst] = dev->absinfo[src];
Henrik Rydberg352ce2b2013-02-15 17:03:57 -080021 dev->absinfo[dst].fuzz = 0;
Henrik Rydberg55e49082012-08-22 20:43:22 +020022 dev->absbit[BIT_WORD(dst)] |= BIT_MASK(dst);
23 }
24}
25
Henrik Rydberg47c78e82010-11-27 09:16:48 +010026/**
Henrik Rydberg8cde8102010-11-27 10:50:54 +010027 * input_mt_init_slots() - initialize MT input slots
Henrik Rydberg47c78e82010-11-27 09:16:48 +010028 * @dev: input device supporting MT events and finger tracking
29 * @num_slots: number of slots used by the device
Henrik Rydberg40a81202012-11-08 09:03:47 -080030 * @flags: mt tasks to handle in core
Henrik Rydberg47c78e82010-11-27 09:16:48 +010031 *
Henrik Rydberg8cde8102010-11-27 10:50:54 +010032 * This function allocates all necessary memory for MT slot handling
Henrik Rydbergc5f4dec2010-12-15 13:50:34 +010033 * in the input device, prepares the ABS_MT_SLOT and
34 * ABS_MT_TRACKING_ID events for use and sets up appropriate buffers.
Henrik Rydberg40a81202012-11-08 09:03:47 -080035 * Depending on the flags set, it also performs pointer emulation and
36 * frame synchronization.
37 *
Henrik Rydbergc5f4dec2010-12-15 13:50:34 +010038 * May be called repeatedly. Returns -EINVAL if attempting to
39 * reinitialize with a different number of slots.
Henrik Rydberg47c78e82010-11-27 09:16:48 +010040 */
Henrik Rydbergb4adbbe2012-08-11 22:07:55 +020041int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots,
42 unsigned int flags)
Henrik Rydberg47c78e82010-11-27 09:16:48 +010043{
Henrik Rydberg8d18fba2012-09-15 15:15:58 +020044 struct input_mt *mt = dev->mt;
Henrik Rydberg47c78e82010-11-27 09:16:48 +010045 int i;
46
47 if (!num_slots)
48 return 0;
Henrik Rydberg8d18fba2012-09-15 15:15:58 +020049 if (mt)
50 return mt->num_slots != num_slots ? -EINVAL : 0;
Henrik Rydberg47c78e82010-11-27 09:16:48 +010051
Henrik Rydberg8d18fba2012-09-15 15:15:58 +020052 mt = kzalloc(sizeof(*mt) + num_slots * sizeof(*mt->slots), GFP_KERNEL);
53 if (!mt)
Henrik Rydberg7c1a8782012-08-12 20:47:05 +020054 goto err_mem;
Henrik Rydberg47c78e82010-11-27 09:16:48 +010055
Henrik Rydberg8d18fba2012-09-15 15:15:58 +020056 mt->num_slots = num_slots;
Henrik Rydbergb4adbbe2012-08-11 22:07:55 +020057 mt->flags = flags;
Henrik Rydberg47c78e82010-11-27 09:16:48 +010058 input_set_abs_params(dev, ABS_MT_SLOT, 0, num_slots - 1, 0, 0);
Henrik Rydbergc5f4dec2010-12-15 13:50:34 +010059 input_set_abs_params(dev, ABS_MT_TRACKING_ID, 0, TRKID_MAX, 0, 0);
Henrik Rydberg47c78e82010-11-27 09:16:48 +010060
Henrik Rydberg55e49082012-08-22 20:43:22 +020061 if (flags & (INPUT_MT_POINTER | INPUT_MT_DIRECT)) {
62 __set_bit(EV_KEY, dev->evbit);
63 __set_bit(BTN_TOUCH, dev->keybit);
64
65 copy_abs(dev, ABS_X, ABS_MT_POSITION_X);
66 copy_abs(dev, ABS_Y, ABS_MT_POSITION_Y);
67 copy_abs(dev, ABS_PRESSURE, ABS_MT_PRESSURE);
68 }
69 if (flags & INPUT_MT_POINTER) {
70 __set_bit(BTN_TOOL_FINGER, dev->keybit);
71 __set_bit(BTN_TOOL_DOUBLETAP, dev->keybit);
72 if (num_slots >= 3)
73 __set_bit(BTN_TOOL_TRIPLETAP, dev->keybit);
74 if (num_slots >= 4)
75 __set_bit(BTN_TOOL_QUADTAP, dev->keybit);
76 if (num_slots >= 5)
77 __set_bit(BTN_TOOL_QUINTTAP, dev->keybit);
78 __set_bit(INPUT_PROP_POINTER, dev->propbit);
79 }
80 if (flags & INPUT_MT_DIRECT)
81 __set_bit(INPUT_PROP_DIRECT, dev->propbit);
Henrik Rydberga0ef6a32013-04-07 20:52:22 -070082 if (flags & INPUT_MT_SEMI_MT)
83 __set_bit(INPUT_PROP_SEMI_MT, dev->propbit);
Henrik Rydberg7c1a8782012-08-12 20:47:05 +020084 if (flags & INPUT_MT_TRACK) {
85 unsigned int n2 = num_slots * num_slots;
86 mt->red = kcalloc(n2, sizeof(*mt->red), GFP_KERNEL);
87 if (!mt->red)
88 goto err_mem;
89 }
Henrik Rydberg55e49082012-08-22 20:43:22 +020090
Benjamin Tissoiresc6275892015-03-30 14:54:15 -040091 /* Mark slots as 'inactive' */
Henrik Rydberg47c78e82010-11-27 09:16:48 +010092 for (i = 0; i < num_slots; i++)
Henrik Rydberg8d18fba2012-09-15 15:15:58 +020093 input_mt_set_value(&mt->slots[i], ABS_MT_TRACKING_ID, -1);
Henrik Rydberg47c78e82010-11-27 09:16:48 +010094
Benjamin Tissoiresc6275892015-03-30 14:54:15 -040095 /* Mark slots as 'unused' */
96 mt->frame = 1;
97
Henrik Rydberg8d18fba2012-09-15 15:15:58 +020098 dev->mt = mt;
Henrik Rydberg47c78e82010-11-27 09:16:48 +010099 return 0;
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200100err_mem:
101 kfree(mt);
102 return -ENOMEM;
Henrik Rydberg47c78e82010-11-27 09:16:48 +0100103}
Henrik Rydberg8cde8102010-11-27 10:50:54 +0100104EXPORT_SYMBOL(input_mt_init_slots);
Henrik Rydberg47c78e82010-11-27 09:16:48 +0100105
106/**
107 * input_mt_destroy_slots() - frees the MT slots of the input device
108 * @dev: input device with allocated MT slots
109 *
110 * This function is only needed in error path as the input core will
111 * automatically free the MT slots when the device is destroyed.
112 */
113void input_mt_destroy_slots(struct input_dev *dev)
114{
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200115 if (dev->mt) {
116 kfree(dev->mt->red);
117 kfree(dev->mt);
118 }
Henrik Rydberg47c78e82010-11-27 09:16:48 +0100119 dev->mt = NULL;
Henrik Rydberg47c78e82010-11-27 09:16:48 +0100120}
121EXPORT_SYMBOL(input_mt_destroy_slots);
Henrik Rydbergc5f4dec2010-12-15 13:50:34 +0100122
123/**
124 * input_mt_report_slot_state() - report contact state
125 * @dev: input device with allocated MT slots
126 * @tool_type: the tool type to use in this slot
127 * @active: true if contact is active, false otherwise
128 *
129 * Reports a contact via ABS_MT_TRACKING_ID, and optionally
130 * ABS_MT_TOOL_TYPE. If active is true and the slot is currently
131 * inactive, or if the tool type is changed, a new tracking id is
132 * assigned to the slot. The tool type is only reported if the
133 * corresponding absbit field is set.
134 */
135void input_mt_report_slot_state(struct input_dev *dev,
136 unsigned int tool_type, bool active)
137{
Henrik Rydberg8d18fba2012-09-15 15:15:58 +0200138 struct input_mt *mt = dev->mt;
139 struct input_mt_slot *slot;
Henrik Rydbergc5f4dec2010-12-15 13:50:34 +0100140 int id;
141
Henrik Rydberg55e49082012-08-22 20:43:22 +0200142 if (!mt)
143 return;
144
145 slot = &mt->slots[mt->slot];
146 slot->frame = mt->frame;
147
148 if (!active) {
Henrik Rydbergc5f4dec2010-12-15 13:50:34 +0100149 input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
150 return;
151 }
152
Henrik Rydberg8d18fba2012-09-15 15:15:58 +0200153 id = input_mt_get_value(slot, ABS_MT_TRACKING_ID);
154 if (id < 0 || input_mt_get_value(slot, ABS_MT_TOOL_TYPE) != tool_type)
155 id = input_mt_new_trkid(mt);
Henrik Rydbergc5f4dec2010-12-15 13:50:34 +0100156
157 input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, id);
158 input_event(dev, EV_ABS, ABS_MT_TOOL_TYPE, tool_type);
159}
160EXPORT_SYMBOL(input_mt_report_slot_state);
161
162/**
163 * input_mt_report_finger_count() - report contact count
164 * @dev: input device with allocated MT slots
165 * @count: the number of contacts
166 *
167 * Reports the contact count via BTN_TOOL_FINGER, BTN_TOOL_DOUBLETAP,
168 * BTN_TOOL_TRIPLETAP and BTN_TOOL_QUADTAP.
169 *
170 * The input core ensures only the KEY events already setup for
171 * this device will produce output.
172 */
173void input_mt_report_finger_count(struct input_dev *dev, int count)
174{
175 input_event(dev, EV_KEY, BTN_TOOL_FINGER, count == 1);
176 input_event(dev, EV_KEY, BTN_TOOL_DOUBLETAP, count == 2);
177 input_event(dev, EV_KEY, BTN_TOOL_TRIPLETAP, count == 3);
178 input_event(dev, EV_KEY, BTN_TOOL_QUADTAP, count == 4);
Daniel Kurtzd5051272011-08-23 23:02:48 -0700179 input_event(dev, EV_KEY, BTN_TOOL_QUINTTAP, count == 5);
Henrik Rydbergc5f4dec2010-12-15 13:50:34 +0100180}
181EXPORT_SYMBOL(input_mt_report_finger_count);
182
183/**
184 * input_mt_report_pointer_emulation() - common pointer emulation
185 * @dev: input device with allocated MT slots
186 * @use_count: report number of active contacts as finger count
187 *
188 * Performs legacy pointer emulation via BTN_TOUCH, ABS_X, ABS_Y and
189 * ABS_PRESSURE. Touchpad finger count is emulated if use_count is true.
190 *
191 * The input core ensures only the KEY and ABS axes already setup for
192 * this device will produce output.
193 */
194void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)
195{
Henrik Rydberg8d18fba2012-09-15 15:15:58 +0200196 struct input_mt *mt = dev->mt;
197 struct input_mt_slot *oldest;
198 int oldid, count, i;
Henrik Rydbergc5f4dec2010-12-15 13:50:34 +0100199
Henrik Rydberg8d18fba2012-09-15 15:15:58 +0200200 if (!mt)
201 return;
202
Dmitry Torokhov51618702012-10-24 23:53:01 -0700203 oldest = NULL;
Henrik Rydberg8d18fba2012-09-15 15:15:58 +0200204 oldid = mt->trkid;
205 count = 0;
206
207 for (i = 0; i < mt->num_slots; ++i) {
208 struct input_mt_slot *ps = &mt->slots[i];
Henrik Rydbergc5f4dec2010-12-15 13:50:34 +0100209 int id = input_mt_get_value(ps, ABS_MT_TRACKING_ID);
210
211 if (id < 0)
212 continue;
213 if ((id - oldid) & TRKID_SGN) {
214 oldest = ps;
215 oldid = id;
216 }
217 count++;
218 }
219
220 input_event(dev, EV_KEY, BTN_TOUCH, count > 0);
221 if (use_count)
222 input_mt_report_finger_count(dev, count);
223
224 if (oldest) {
225 int x = input_mt_get_value(oldest, ABS_MT_POSITION_X);
226 int y = input_mt_get_value(oldest, ABS_MT_POSITION_Y);
Henrik Rydbergc5f4dec2010-12-15 13:50:34 +0100227
228 input_event(dev, EV_ABS, ABS_X, x);
229 input_event(dev, EV_ABS, ABS_Y, y);
Henrik Rydberg22739292012-09-15 08:57:18 +0200230
231 if (test_bit(ABS_MT_PRESSURE, dev->absbit)) {
232 int p = input_mt_get_value(oldest, ABS_MT_PRESSURE);
233 input_event(dev, EV_ABS, ABS_PRESSURE, p);
234 }
Henrik Rydbergc5f4dec2010-12-15 13:50:34 +0100235 } else {
Henrik Rydberg22739292012-09-15 08:57:18 +0200236 if (test_bit(ABS_MT_PRESSURE, dev->absbit))
237 input_event(dev, EV_ABS, ABS_PRESSURE, 0);
Henrik Rydbergc5f4dec2010-12-15 13:50:34 +0100238 }
239}
240EXPORT_SYMBOL(input_mt_report_pointer_emulation);
Henrik Rydberg55e49082012-08-22 20:43:22 +0200241
Dmitry Torokhov8ff21f42014-08-25 11:31:02 -0700242static void __input_mt_drop_unused(struct input_dev *dev, struct input_mt *mt)
243{
244 int i;
245
246 for (i = 0; i < mt->num_slots; i++) {
247 if (!input_mt_is_used(mt, &mt->slots[i])) {
248 input_mt_slot(dev, i);
249 input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
250 }
251 }
252}
253
Henrik Rydberg55e49082012-08-22 20:43:22 +0200254/**
Henrik Rydbergf8ec8942014-07-25 17:16:42 -0700255 * input_mt_drop_unused() - Inactivate slots not seen in this frame
256 * @dev: input device with allocated MT slots
257 *
258 * Lift all slots not seen since the last call to this function.
259 */
260void input_mt_drop_unused(struct input_dev *dev)
261{
262 struct input_mt *mt = dev->mt;
Henrik Rydbergf8ec8942014-07-25 17:16:42 -0700263
Dmitry Torokhov8ff21f42014-08-25 11:31:02 -0700264 if (mt) {
265 __input_mt_drop_unused(dev, mt);
266 mt->frame++;
Henrik Rydbergf8ec8942014-07-25 17:16:42 -0700267 }
Henrik Rydbergf8ec8942014-07-25 17:16:42 -0700268}
269EXPORT_SYMBOL(input_mt_drop_unused);
270
271/**
Henrik Rydberg55e49082012-08-22 20:43:22 +0200272 * input_mt_sync_frame() - synchronize mt frame
273 * @dev: input device with allocated MT slots
274 *
275 * Close the frame and prepare the internal state for a new one.
276 * Depending on the flags, marks unused slots as inactive and performs
277 * pointer emulation.
278 */
279void input_mt_sync_frame(struct input_dev *dev)
280{
281 struct input_mt *mt = dev->mt;
Henrik Rydberga0ef6a32013-04-07 20:52:22 -0700282 bool use_count = false;
Henrik Rydberg55e49082012-08-22 20:43:22 +0200283
284 if (!mt)
285 return;
286
Henrik Rydbergf8ec8942014-07-25 17:16:42 -0700287 if (mt->flags & INPUT_MT_DROP_UNUSED)
Dmitry Torokhov8ff21f42014-08-25 11:31:02 -0700288 __input_mt_drop_unused(dev, mt);
Henrik Rydberg55e49082012-08-22 20:43:22 +0200289
Henrik Rydberga0ef6a32013-04-07 20:52:22 -0700290 if ((mt->flags & INPUT_MT_POINTER) && !(mt->flags & INPUT_MT_SEMI_MT))
291 use_count = true;
292
293 input_mt_report_pointer_emulation(dev, use_count);
Dmitry Torokhov8ff21f42014-08-25 11:31:02 -0700294
295 mt->frame++;
Henrik Rydberg55e49082012-08-22 20:43:22 +0200296}
297EXPORT_SYMBOL(input_mt_sync_frame);
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200298
Henrik Rydberg448c7f382015-02-01 11:25:14 -0800299static int adjust_dual(int *begin, int step, int *end, int eq, int mu)
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200300{
301 int f, *p, s, c;
302
303 if (begin == end)
304 return 0;
305
306 f = *begin;
307 p = begin + step;
308 s = p == end ? f + 1 : *p;
309
310 for (; p != end; p += step)
311 if (*p < f)
312 s = f, f = *p;
313 else if (*p < s)
314 s = *p;
315
316 c = (f + s + 1) / 2;
Henrik Rydberg448c7f382015-02-01 11:25:14 -0800317 if (c == 0 || (c > mu && (!eq || mu > 0)))
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200318 return 0;
Henrik Rydberg448c7f382015-02-01 11:25:14 -0800319 /* Improve convergence for positive matrices by penalizing overcovers */
320 if (s < 0 && mu <= 0)
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200321 c *= 2;
322
323 for (p = begin; p != end; p += step)
324 *p -= c;
325
326 return (c < s && s <= 0) || (f >= 0 && f < c);
327}
328
Henrik Rydberg448c7f382015-02-01 11:25:14 -0800329static void find_reduced_matrix(int *w, int nr, int nc, int nrc, int mu)
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200330{
331 int i, k, sum;
332
333 for (k = 0; k < nrc; k++) {
334 for (i = 0; i < nr; i++)
Henrik Rydberg448c7f382015-02-01 11:25:14 -0800335 adjust_dual(w + i, nr, w + i + nrc, nr <= nc, mu);
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200336 sum = 0;
337 for (i = 0; i < nrc; i += nr)
Henrik Rydberg448c7f382015-02-01 11:25:14 -0800338 sum += adjust_dual(w + i, 1, w + i + nr, nc <= nr, mu);
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200339 if (!sum)
340 break;
341 }
342}
343
344static int input_mt_set_matrix(struct input_mt *mt,
Henrik Rydberg448c7f382015-02-01 11:25:14 -0800345 const struct input_mt_pos *pos, int num_pos,
346 int mu)
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200347{
348 const struct input_mt_pos *p;
349 struct input_mt_slot *s;
350 int *w = mt->red;
351 int x, y;
352
353 for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
354 if (!input_mt_is_active(s))
355 continue;
356 x = input_mt_get_value(s, ABS_MT_POSITION_X);
357 y = input_mt_get_value(s, ABS_MT_POSITION_Y);
358 for (p = pos; p != pos + num_pos; p++) {
359 int dx = x - p->x, dy = y - p->y;
Henrik Rydberg448c7f382015-02-01 11:25:14 -0800360 *w++ = dx * dx + dy * dy - mu;
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200361 }
362 }
363
364 return w - mt->red;
365}
366
367static void input_mt_set_slots(struct input_mt *mt,
368 int *slots, int num_pos)
369{
370 struct input_mt_slot *s;
Benjamin Tissoires73e8a8e2015-04-05 13:41:35 -0700371 int *w = mt->red, j;
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200372
Benjamin Tissoires73e8a8e2015-04-05 13:41:35 -0700373 for (j = 0; j != num_pos; j++)
374 slots[j] = -1;
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200375
376 for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
377 if (!input_mt_is_active(s))
378 continue;
Benjamin Tissoires73e8a8e2015-04-05 13:41:35 -0700379
380 for (j = 0; j != num_pos; j++) {
381 if (w[j] < 0) {
382 slots[j] = s - mt->slots;
383 break;
384 }
385 }
386
387 w += num_pos;
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200388 }
389
390 for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
391 if (input_mt_is_active(s))
392 continue;
Benjamin Tissoires73e8a8e2015-04-05 13:41:35 -0700393
394 for (j = 0; j != num_pos; j++) {
395 if (slots[j] < 0) {
396 slots[j] = s - mt->slots;
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200397 break;
398 }
Benjamin Tissoires73e8a8e2015-04-05 13:41:35 -0700399 }
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200400 }
401}
402
403/**
404 * input_mt_assign_slots() - perform a best-match assignment
405 * @dev: input device with allocated MT slots
406 * @slots: the slot assignment to be filled
407 * @pos: the position array to match
408 * @num_pos: number of positions
Henrik Rydberg448c7f382015-02-01 11:25:14 -0800409 * @dmax: maximum ABS_MT_POSITION displacement (zero for infinite)
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200410 *
411 * Performs a best match against the current contacts and returns
412 * the slot assignment list. New contacts are assigned to unused
413 * slots.
414 *
Henrik Rydberg448c7f382015-02-01 11:25:14 -0800415 * The assignments are balanced so that all coordinate displacements are
416 * below the euclidian distance dmax. If no such assignment can be found,
417 * some contacts are assigned to unused slots.
418 *
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200419 * Returns zero on success, or negative error in case of failure.
420 */
421int input_mt_assign_slots(struct input_dev *dev, int *slots,
Henrik Rydberg448c7f382015-02-01 11:25:14 -0800422 const struct input_mt_pos *pos, int num_pos,
423 int dmax)
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200424{
425 struct input_mt *mt = dev->mt;
Henrik Rydberg448c7f382015-02-01 11:25:14 -0800426 int mu = 2 * dmax * dmax;
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200427 int nrc;
428
429 if (!mt || !mt->red)
430 return -ENXIO;
431 if (num_pos > mt->num_slots)
432 return -EINVAL;
433 if (num_pos < 1)
434 return 0;
435
Henrik Rydberg448c7f382015-02-01 11:25:14 -0800436 nrc = input_mt_set_matrix(mt, pos, num_pos, mu);
437 find_reduced_matrix(mt->red, num_pos, nrc / num_pos, nrc, mu);
Henrik Rydberg7c1a8782012-08-12 20:47:05 +0200438 input_mt_set_slots(mt, slots, num_pos);
439
440 return 0;
441}
442EXPORT_SYMBOL(input_mt_assign_slots);
Henrik Rydberg17a465a2012-09-01 09:27:20 +0200443
444/**
445 * input_mt_get_slot_by_key() - return slot matching key
446 * @dev: input device with allocated MT slots
447 * @key: the key of the sought slot
448 *
449 * Returns the slot of the given key, if it exists, otherwise
450 * set the key on the first unused slot and return.
451 *
452 * If no available slot can be found, -1 is returned.
Benjamin Tissoiresc6275892015-03-30 14:54:15 -0400453 * Note that for this function to work properly, input_mt_sync_frame() has
454 * to be called at each frame.
Henrik Rydberg17a465a2012-09-01 09:27:20 +0200455 */
456int input_mt_get_slot_by_key(struct input_dev *dev, int key)
457{
458 struct input_mt *mt = dev->mt;
459 struct input_mt_slot *s;
460
461 if (!mt)
462 return -1;
463
464 for (s = mt->slots; s != mt->slots + mt->num_slots; s++)
465 if (input_mt_is_active(s) && s->key == key)
466 return s - mt->slots;
467
468 for (s = mt->slots; s != mt->slots + mt->num_slots; s++)
Benjamin Tissoiresc6275892015-03-30 14:54:15 -0400469 if (!input_mt_is_active(s) && !input_mt_is_used(mt, s)) {
Henrik Rydberg17a465a2012-09-01 09:27:20 +0200470 s->key = key;
471 return s - mt->slots;
472 }
473
474 return -1;
475}
476EXPORT_SYMBOL(input_mt_get_slot_by_key);