Root/drivers/input/input-mt.c

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_TRACK) {
83        unsigned int n2 = num_slots * num_slots;
84        mt->red = kcalloc(n2, sizeof(*mt->red), GFP_KERNEL);
85        if (!mt->red)
86            goto err_mem;
87    }
88
89    /* Mark slots as 'unused' */
90    for (i = 0; i < num_slots; i++)
91        input_mt_set_value(&mt->slots[i], ABS_MT_TRACKING_ID, -1);
92
93    dev->mt = mt;
94    return 0;
95err_mem:
96    kfree(mt);
97    return -ENOMEM;
98}
99EXPORT_SYMBOL(input_mt_init_slots);
100
101/**
102 * input_mt_destroy_slots() - frees the MT slots of the input device
103 * @dev: input device with allocated MT slots
104 *
105 * This function is only needed in error path as the input core will
106 * automatically free the MT slots when the device is destroyed.
107 */
108void input_mt_destroy_slots(struct input_dev *dev)
109{
110    if (dev->mt) {
111        kfree(dev->mt->red);
112        kfree(dev->mt);
113    }
114    dev->mt = NULL;
115}
116EXPORT_SYMBOL(input_mt_destroy_slots);
117
118/**
119 * input_mt_report_slot_state() - report contact state
120 * @dev: input device with allocated MT slots
121 * @tool_type: the tool type to use in this slot
122 * @active: true if contact is active, false otherwise
123 *
124 * Reports a contact via ABS_MT_TRACKING_ID, and optionally
125 * ABS_MT_TOOL_TYPE. If active is true and the slot is currently
126 * inactive, or if the tool type is changed, a new tracking id is
127 * assigned to the slot. The tool type is only reported if the
128 * corresponding absbit field is set.
129 */
130void input_mt_report_slot_state(struct input_dev *dev,
131                unsigned int tool_type, bool active)
132{
133    struct input_mt *mt = dev->mt;
134    struct input_mt_slot *slot;
135    int id;
136
137    if (!mt)
138        return;
139
140    slot = &mt->slots[mt->slot];
141    slot->frame = mt->frame;
142
143    if (!active) {
144        input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
145        return;
146    }
147
148    id = input_mt_get_value(slot, ABS_MT_TRACKING_ID);
149    if (id < 0 || input_mt_get_value(slot, ABS_MT_TOOL_TYPE) != tool_type)
150        id = input_mt_new_trkid(mt);
151
152    input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, id);
153    input_event(dev, EV_ABS, ABS_MT_TOOL_TYPE, tool_type);
154}
155EXPORT_SYMBOL(input_mt_report_slot_state);
156
157/**
158 * input_mt_report_finger_count() - report contact count
159 * @dev: input device with allocated MT slots
160 * @count: the number of contacts
161 *
162 * Reports the contact count via BTN_TOOL_FINGER, BTN_TOOL_DOUBLETAP,
163 * BTN_TOOL_TRIPLETAP and BTN_TOOL_QUADTAP.
164 *
165 * The input core ensures only the KEY events already setup for
166 * this device will produce output.
167 */
168void input_mt_report_finger_count(struct input_dev *dev, int count)
169{
170    input_event(dev, EV_KEY, BTN_TOOL_FINGER, count == 1);
171    input_event(dev, EV_KEY, BTN_TOOL_DOUBLETAP, count == 2);
172    input_event(dev, EV_KEY, BTN_TOOL_TRIPLETAP, count == 3);
173    input_event(dev, EV_KEY, BTN_TOOL_QUADTAP, count == 4);
174    input_event(dev, EV_KEY, BTN_TOOL_QUINTTAP, count == 5);
175}
176EXPORT_SYMBOL(input_mt_report_finger_count);
177
178/**
179 * input_mt_report_pointer_emulation() - common pointer emulation
180 * @dev: input device with allocated MT slots
181 * @use_count: report number of active contacts as finger count
182 *
183 * Performs legacy pointer emulation via BTN_TOUCH, ABS_X, ABS_Y and
184 * ABS_PRESSURE. Touchpad finger count is emulated if use_count is true.
185 *
186 * The input core ensures only the KEY and ABS axes already setup for
187 * this device will produce output.
188 */
189void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)
190{
191    struct input_mt *mt = dev->mt;
192    struct input_mt_slot *oldest;
193    int oldid, count, i;
194
195    if (!mt)
196        return;
197
198    oldest = NULL;
199    oldid = mt->trkid;
200    count = 0;
201
202    for (i = 0; i < mt->num_slots; ++i) {
203        struct input_mt_slot *ps = &mt->slots[i];
204        int id = input_mt_get_value(ps, ABS_MT_TRACKING_ID);
205
206        if (id < 0)
207            continue;
208        if ((id - oldid) & TRKID_SGN) {
209            oldest = ps;
210            oldid = id;
211        }
212        count++;
213    }
214
215    input_event(dev, EV_KEY, BTN_TOUCH, count > 0);
216    if (use_count)
217        input_mt_report_finger_count(dev, count);
218
219    if (oldest) {
220        int x = input_mt_get_value(oldest, ABS_MT_POSITION_X);
221        int y = input_mt_get_value(oldest, ABS_MT_POSITION_Y);
222
223        input_event(dev, EV_ABS, ABS_X, x);
224        input_event(dev, EV_ABS, ABS_Y, y);
225
226        if (test_bit(ABS_MT_PRESSURE, dev->absbit)) {
227            int p = input_mt_get_value(oldest, ABS_MT_PRESSURE);
228            input_event(dev, EV_ABS, ABS_PRESSURE, p);
229        }
230    } else {
231        if (test_bit(ABS_MT_PRESSURE, dev->absbit))
232            input_event(dev, EV_ABS, ABS_PRESSURE, 0);
233    }
234}
235EXPORT_SYMBOL(input_mt_report_pointer_emulation);
236
237/**
238 * input_mt_sync_frame() - synchronize mt frame
239 * @dev: input device with allocated MT slots
240 *
241 * Close the frame and prepare the internal state for a new one.
242 * Depending on the flags, marks unused slots as inactive and performs
243 * pointer emulation.
244 */
245void input_mt_sync_frame(struct input_dev *dev)
246{
247    struct input_mt *mt = dev->mt;
248    struct input_mt_slot *s;
249
250    if (!mt)
251        return;
252
253    if (mt->flags & INPUT_MT_DROP_UNUSED) {
254        for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
255            if (input_mt_is_used(mt, s))
256                continue;
257            input_mt_slot(dev, s - mt->slots);
258            input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
259        }
260    }
261
262    input_mt_report_pointer_emulation(dev, (mt->flags & INPUT_MT_POINTER));
263
264    mt->frame++;
265}
266EXPORT_SYMBOL(input_mt_sync_frame);
267
268static int adjust_dual(int *begin, int step, int *end, int eq)
269{
270    int f, *p, s, c;
271
272    if (begin == end)
273        return 0;
274
275    f = *begin;
276    p = begin + step;
277    s = p == end ? f + 1 : *p;
278
279    for (; p != end; p += step)
280        if (*p < f)
281            s = f, f = *p;
282        else if (*p < s)
283            s = *p;
284
285    c = (f + s + 1) / 2;
286    if (c == 0 || (c > 0 && !eq))
287        return 0;
288    if (s < 0)
289        c *= 2;
290
291    for (p = begin; p != end; p += step)
292        *p -= c;
293
294    return (c < s && s <= 0) || (f >= 0 && f < c);
295}
296
297static void find_reduced_matrix(int *w, int nr, int nc, int nrc)
298{
299    int i, k, sum;
300
301    for (k = 0; k < nrc; k++) {
302        for (i = 0; i < nr; i++)
303            adjust_dual(w + i, nr, w + i + nrc, nr <= nc);
304        sum = 0;
305        for (i = 0; i < nrc; i += nr)
306            sum += adjust_dual(w + i, 1, w + i + nr, nc <= nr);
307        if (!sum)
308            break;
309    }
310}
311
312static int input_mt_set_matrix(struct input_mt *mt,
313                   const struct input_mt_pos *pos, int num_pos)
314{
315    const struct input_mt_pos *p;
316    struct input_mt_slot *s;
317    int *w = mt->red;
318    int x, y;
319
320    for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
321        if (!input_mt_is_active(s))
322            continue;
323        x = input_mt_get_value(s, ABS_MT_POSITION_X);
324        y = input_mt_get_value(s, ABS_MT_POSITION_Y);
325        for (p = pos; p != pos + num_pos; p++) {
326            int dx = x - p->x, dy = y - p->y;
327            *w++ = dx * dx + dy * dy;
328        }
329    }
330
331    return w - mt->red;
332}
333
334static void input_mt_set_slots(struct input_mt *mt,
335                   int *slots, int num_pos)
336{
337    struct input_mt_slot *s;
338    int *w = mt->red, *p;
339
340    for (p = slots; p != slots + num_pos; p++)
341        *p = -1;
342
343    for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
344        if (!input_mt_is_active(s))
345            continue;
346        for (p = slots; p != slots + num_pos; p++)
347            if (*w++ < 0)
348                *p = s - mt->slots;
349    }
350
351    for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
352        if (input_mt_is_active(s))
353            continue;
354        for (p = slots; p != slots + num_pos; p++)
355            if (*p < 0) {
356                *p = s - mt->slots;
357                break;
358            }
359    }
360}
361
362/**
363 * input_mt_assign_slots() - perform a best-match assignment
364 * @dev: input device with allocated MT slots
365 * @slots: the slot assignment to be filled
366 * @pos: the position array to match
367 * @num_pos: number of positions
368 *
369 * Performs a best match against the current contacts and returns
370 * the slot assignment list. New contacts are assigned to unused
371 * slots.
372 *
373 * Returns zero on success, or negative error in case of failure.
374 */
375int input_mt_assign_slots(struct input_dev *dev, int *slots,
376              const struct input_mt_pos *pos, int num_pos)
377{
378    struct input_mt *mt = dev->mt;
379    int nrc;
380
381    if (!mt || !mt->red)
382        return -ENXIO;
383    if (num_pos > mt->num_slots)
384        return -EINVAL;
385    if (num_pos < 1)
386        return 0;
387
388    nrc = input_mt_set_matrix(mt, pos, num_pos);
389    find_reduced_matrix(mt->red, num_pos, nrc / num_pos, nrc);
390    input_mt_set_slots(mt, slots, num_pos);
391
392    return 0;
393}
394EXPORT_SYMBOL(input_mt_assign_slots);
395
396/**
397 * input_mt_get_slot_by_key() - return slot matching key
398 * @dev: input device with allocated MT slots
399 * @key: the key of the sought slot
400 *
401 * Returns the slot of the given key, if it exists, otherwise
402 * set the key on the first unused slot and return.
403 *
404 * If no available slot can be found, -1 is returned.
405 */
406int input_mt_get_slot_by_key(struct input_dev *dev, int key)
407{
408    struct input_mt *mt = dev->mt;
409    struct input_mt_slot *s;
410
411    if (!mt)
412        return -1;
413
414    for (s = mt->slots; s != mt->slots + mt->num_slots; s++)
415        if (input_mt_is_active(s) && s->key == key)
416            return s - mt->slots;
417
418    for (s = mt->slots; s != mt->slots + mt->num_slots; s++)
419        if (!input_mt_is_active(s)) {
420            s->key = key;
421            return s - mt->slots;
422        }
423
424    return -1;
425}
426EXPORT_SYMBOL(input_mt_get_slot_by_key);
427

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