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/export.h>
13#include <linux/slab.h>
14
15#define TRKID_SGN	((TRKID_MAX + 1) >> 1)
16
17static 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];
21		dev->absinfo[dst].fuzz = 0;
22		dev->absbit[BIT_WORD(dst)] |= BIT_MASK(dst);
23	}
24}
25
26/**
27 * input_mt_init_slots() - initialize MT input slots
28 * @dev: input device supporting MT events and finger tracking
29 * @num_slots: number of slots used by the device
30 * @flags: mt tasks to handle in core
31 *
32 * This function allocates all necessary memory for MT slot handling
33 * in the input device, prepares the ABS_MT_SLOT and
34 * ABS_MT_TRACKING_ID events for use and sets up appropriate buffers.
35 * Depending on the flags set, it also performs pointer emulation and
36 * frame synchronization.
37 *
38 * May be called repeatedly. Returns -EINVAL if attempting to
39 * reinitialize with a different number of slots.
40 */
41int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots,
42			unsigned int flags)
43{
44	struct input_mt *mt = dev->mt;
45	int i;
46
47	if (!num_slots)
48		return 0;
49	if (mt)
50		return mt->num_slots != num_slots ? -EINVAL : 0;
51
52	mt = kzalloc(sizeof(*mt) + num_slots * sizeof(*mt->slots), GFP_KERNEL);
53	if (!mt)
54		goto err_mem;
55
56	mt->num_slots = num_slots;
57	mt->flags = flags;
58	input_set_abs_params(dev, ABS_MT_SLOT, 0, num_slots - 1, 0, 0);
59	input_set_abs_params(dev, ABS_MT_TRACKING_ID, 0, TRKID_MAX, 0, 0);
60
61	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);
82	if (flags & INPUT_MT_SEMI_MT)
83		__set_bit(INPUT_PROP_SEMI_MT, dev->propbit);
84	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	}
90
91	/* Mark slots as 'inactive' */
92	for (i = 0; i < num_slots; i++)
93		input_mt_set_value(&mt->slots[i], ABS_MT_TRACKING_ID, -1);
94
95	/* Mark slots as 'unused' */
96	mt->frame = 1;
97
98	dev->mt = mt;
99	return 0;
100err_mem:
101	kfree(mt);
102	return -ENOMEM;
103}
104EXPORT_SYMBOL(input_mt_init_slots);
105
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{
115	if (dev->mt) {
116		kfree(dev->mt->red);
117		kfree(dev->mt);
118	}
119	dev->mt = NULL;
120}
121EXPORT_SYMBOL(input_mt_destroy_slots);
122
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{
138	struct input_mt *mt = dev->mt;
139	struct input_mt_slot *slot;
140	int id;
141
142	if (!mt)
143		return;
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;
151	}
152
153	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);
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}
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);
179	input_event(dev, EV_KEY, BTN_TOOL_QUINTTAP, count == 5);
180}
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{
196	struct input_mt *mt = dev->mt;
197	struct input_mt_slot *oldest;
198	int oldid, count, i;
199
200	if (!mt)
201		return;
202
203	oldest = NULL;
204	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];
209		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);
227
228		input_event(dev, EV_ABS, ABS_X, x);
229		input_event(dev, EV_ABS, ABS_Y, y);
230
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		}
235	} else {
236		if (test_bit(ABS_MT_PRESSURE, dev->absbit))
237			input_event(dev, EV_ABS, ABS_PRESSURE, 0);
238	}
239}
240EXPORT_SYMBOL(input_mt_report_pointer_emulation);
241
242static 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
254/**
255 * 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;
263
264	if (mt) {
265		__input_mt_drop_unused(dev, mt);
266		mt->frame++;
267	}
268}
269EXPORT_SYMBOL(input_mt_drop_unused);
270
271/**
272 * 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;
282	bool use_count = false;
283
284	if (!mt)
285		return;
286
287	if (mt->flags & INPUT_MT_DROP_UNUSED)
288		__input_mt_drop_unused(dev, mt);
289
290	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);
294
295	mt->frame++;
296}
297EXPORT_SYMBOL(input_mt_sync_frame);
298
299static int adjust_dual(int *begin, int step, int *end, int eq, int mu)
300{
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;
317	if (c == 0 || (c > mu && (!eq || mu > 0)))
318		return 0;
319	/* Improve convergence for positive matrices by penalizing overcovers */
320	if (s < 0 && mu <= 0)
321		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
329static void find_reduced_matrix(int *w, int nr, int nc, int nrc, int mu)
330{
331	int i, k, sum;
332
333	for (k = 0; k < nrc; k++) {
334		for (i = 0; i < nr; i++)
335			adjust_dual(w + i, nr, w + i + nrc, nr <= nc, mu);
336		sum = 0;
337		for (i = 0; i < nrc; i += nr)
338			sum += adjust_dual(w + i, 1, w + i + nr, nc <= nr, mu);
339		if (!sum)
340			break;
341	}
342}
343
344static int input_mt_set_matrix(struct input_mt *mt,
345			       const struct input_mt_pos *pos, int num_pos,
346			       int mu)
347{
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;
360			*w++ = dx * dx + dy * dy - mu;
361		}
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;
371	int *w = mt->red, j;
372
373	for (j = 0; j != num_pos; j++)
374		slots[j] = -1;
375
376	for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
377		if (!input_mt_is_active(s))
378			continue;
379
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;
388	}
389
390	for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
391		if (input_mt_is_active(s))
392			continue;
393
394		for (j = 0; j != num_pos; j++) {
395			if (slots[j] < 0) {
396				slots[j] = s - mt->slots;
397				break;
398			}
399		}
400	}
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
409 * @dmax: maximum ABS_MT_POSITION displacement (zero for infinite)
410 *
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 *
415 * 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 *
419 * Returns zero on success, or negative error in case of failure.
420 */
421int input_mt_assign_slots(struct input_dev *dev, int *slots,
422			  const struct input_mt_pos *pos, int num_pos,
423			  int dmax)
424{
425	struct input_mt *mt = dev->mt;
426	int mu = 2 * dmax * dmax;
427	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
436	nrc = input_mt_set_matrix(mt, pos, num_pos, mu);
437	find_reduced_matrix(mt->red, num_pos, nrc / num_pos, nrc, mu);
438	input_mt_set_slots(mt, slots, num_pos);
439
440	return 0;
441}
442EXPORT_SYMBOL(input_mt_assign_slots);
443
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.
453 * Note that for this function to work properly, input_mt_sync_frame() has
454 * to be called at each frame.
455 */
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++)
469		if (!input_mt_is_active(s) && !input_mt_is_used(mt, s)) {
470			s->key = key;
471			return s - mt->slots;
472		}
473
474	return -1;
475}
476EXPORT_SYMBOL(input_mt_get_slot_by_key);
477