linux/drivers/input/input-mt.c
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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/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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