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
  17 static 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  */
  41 int 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(struct_size(mt, slots, num_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;
 100 err_mem:
 101         kfree(mt);
 102         return -ENOMEM;
 103 }
 104 EXPORT_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  */
 113 void 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 }
 121 EXPORT_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  *
 135  * Returns true if contact is active.
 136  */
 137 bool input_mt_report_slot_state(struct input_dev *dev,
 138                                 unsigned int tool_type, bool active)
 139 {
 140         struct input_mt *mt = dev->mt;
 141         struct input_mt_slot *slot;
 142         int id;
 143
 144         if (!mt)
 145                 return false;
 146
 147         slot = &mt->slots[mt->slot];
 148         slot->frame = mt->frame;
 149
 150         if (!active) {
 151                 input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
 152                 return false;
 153         }
 154
 155         id = input_mt_get_value(slot, ABS_MT_TRACKING_ID);
 156         if (id < 0)
 157                 id = input_mt_new_trkid(mt);
 158
 159         input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, id);
 160         input_event(dev, EV_ABS, ABS_MT_TOOL_TYPE, tool_type);
 161
 162         return true;
 163 }
 164 EXPORT_SYMBOL(input_mt_report_slot_state);
 165
 166 /**
 167  * input_mt_report_finger_count() - report contact count
 168  * @dev: input device with allocated MT slots
 169  * @count: the number of contacts
 170  *
 171  * Reports the contact count via BTN_TOOL_FINGER, BTN_TOOL_DOUBLETAP,
 172  * BTN_TOOL_TRIPLETAP and BTN_TOOL_QUADTAP.
 173  *
 174  * The input core ensures only the KEY events already setup for
 175  * this device will produce output.
 176  */
 177 void input_mt_report_finger_count(struct input_dev *dev, int count)
 178 {
 179         input_event(dev, EV_KEY, BTN_TOOL_FINGER, count == 1);
 180         input_event(dev, EV_KEY, BTN_TOOL_DOUBLETAP, count == 2);
 181         input_event(dev, EV_KEY, BTN_TOOL_TRIPLETAP, count == 3);
 182         input_event(dev, EV_KEY, BTN_TOOL_QUADTAP, count == 4);
 183         input_event(dev, EV_KEY, BTN_TOOL_QUINTTAP, count == 5);
 184 }
 185 EXPORT_SYMBOL(input_mt_report_finger_count);
 186
 187 /**
 188  * input_mt_report_pointer_emulation() - common pointer emulation
 189  * @dev: input device with allocated MT slots
 190  * @use_count: report number of active contacts as finger count
 191  *
 192  * Performs legacy pointer emulation via BTN_TOUCH, ABS_X, ABS_Y and
 193  * ABS_PRESSURE. Touchpad finger count is emulated if use_count is true.
 194  *
 195  * The input core ensures only the KEY and ABS axes already setup for
 196  * this device will produce output.
 197  */
 198 void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)
 199 {
 200         struct input_mt *mt = dev->mt;
 201         struct input_mt_slot *oldest;
 202         int oldid, count, i;
 203
 204         if (!mt)
 205                 return;
 206
 207         oldest = NULL;
 208         oldid = mt->trkid;
 209         count = 0;
 210
 211         for (i = 0; i < mt->num_slots; ++i) {
 212                 struct input_mt_slot *ps = &mt->slots[i];
 213                 int id = input_mt_get_value(ps, ABS_MT_TRACKING_ID);
 214
 215                 if (id < 0)
 216                         continue;
 217                 if ((id - oldid) & TRKID_SGN) {
 218                         oldest = ps;
 219                         oldid = id;
 220                 }
 221                 count++;
 222         }
 223
 224         input_event(dev, EV_KEY, BTN_TOUCH, count > 0);
 225
 226         if (use_count) {
 227                 if (count == 0 &&
 228                     !test_bit(ABS_MT_DISTANCE, dev->absbit) &&
 229                     test_bit(ABS_DISTANCE, dev->absbit) &&
 230                     input_abs_get_val(dev, ABS_DISTANCE) != 0) {
 231                         /*
 232                          * Force reporting BTN_TOOL_FINGER for devices that
 233                          * only report general hover (and not per-contact
 234                          * distance) when contact is in proximity but not
 235                          * on the surface.
 236                          */
 237                         count = 1;
 238                 }
 239
 240                 input_mt_report_finger_count(dev, count);
 241         }
 242
 243         if (oldest) {
 244                 int x = input_mt_get_value(oldest, ABS_MT_POSITION_X);
 245                 int y = input_mt_get_value(oldest, ABS_MT_POSITION_Y);
 246
 247                 input_event(dev, EV_ABS, ABS_X, x);
 248                 input_event(dev, EV_ABS, ABS_Y, y);
 249
 250                 if (test_bit(ABS_MT_PRESSURE, dev->absbit)) {
 251                         int p = input_mt_get_value(oldest, ABS_MT_PRESSURE);
 252                         input_event(dev, EV_ABS, ABS_PRESSURE, p);
 253                 }
 254         } else {
 255                 if (test_bit(ABS_MT_PRESSURE, dev->absbit))
 256                         input_event(dev, EV_ABS, ABS_PRESSURE, 0);
 257         }
 258 }
 259 EXPORT_SYMBOL(input_mt_report_pointer_emulation);
 260
 261 static void __input_mt_drop_unused(struct input_dev *dev, struct input_mt *mt)
 262 {
 263         int i;
 264
 265         for (i = 0; i < mt->num_slots; i++) {
 266                 if (!input_mt_is_used(mt, &mt->slots[i])) {
 267                         input_mt_slot(dev, i);
 268                         input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
 269                 }
 270         }
 271 }
 272
 273 /**
 274  * input_mt_drop_unused() - Inactivate slots not seen in this frame
 275  * @dev: input device with allocated MT slots
 276  *
 277  * Lift all slots not seen since the last call to this function.
 278  */
 279 void input_mt_drop_unused(struct input_dev *dev)
 280 {
 281         struct input_mt *mt = dev->mt;
 282
 283         if (mt) {
 284                 __input_mt_drop_unused(dev, mt);
 285                 mt->frame++;
 286         }
 287 }
 288 EXPORT_SYMBOL(input_mt_drop_unused);
 289
 290 /**
 291  * input_mt_sync_frame() - synchronize mt frame
 292  * @dev: input device with allocated MT slots
 293  *
 294  * Close the frame and prepare the internal state for a new one.
 295  * Depending on the flags, marks unused slots as inactive and performs
 296  * pointer emulation.
 297  */
 298 void input_mt_sync_frame(struct input_dev *dev)
 299 {
 300         struct input_mt *mt = dev->mt;
 301         bool use_count = false;
 302
 303         if (!mt)
 304                 return;
 305
 306         if (mt->flags & INPUT_MT_DROP_UNUSED)
 307                 __input_mt_drop_unused(dev, mt);
 308
 309         if ((mt->flags & INPUT_MT_POINTER) && !(mt->flags & INPUT_MT_SEMI_MT))
 310                 use_count = true;
 311
 312         input_mt_report_pointer_emulation(dev, use_count);
 313
 314         mt->frame++;
 315 }
 316 EXPORT_SYMBOL(input_mt_sync_frame);
 317
 318 static int adjust_dual(int *begin, int step, int *end, int eq, int mu)
 319 {
 320         int f, *p, s, c;
 321
 322         if (begin == end)
 323                 return 0;
 324
 325         f = *begin;
 326         p = begin + step;
 327         s = p == end ? f + 1 : *p;
 328
 329         for (; p != end; p += step)
 330                 if (*p < f)
 331                         s = f, f = *p;
 332                 else if (*p < s)
 333                         s = *p;
 334
 335         c = (f + s + 1) / 2;
 336         if (c == 0 || (c > mu && (!eq || mu > 0)))
 337                 return 0;
 338         /* Improve convergence for positive matrices by penalizing overcovers */
 339         if (s < 0 && mu <= 0)
 340                 c *= 2;
 341
 342         for (p = begin; p != end; p += step)
 343                 *p -= c;
 344
 345         return (c < s && s <= 0) || (f >= 0 && f < c);
 346 }
 347
 348 static void find_reduced_matrix(int *w, int nr, int nc, int nrc, int mu)
 349 {
 350         int i, k, sum;
 351
 352         for (k = 0; k < nrc; k++) {
 353                 for (i = 0; i < nr; i++)
 354                         adjust_dual(w + i, nr, w + i + nrc, nr <= nc, mu);
 355                 sum = 0;
 356                 for (i = 0; i < nrc; i += nr)
 357                         sum += adjust_dual(w + i, 1, w + i + nr, nc <= nr, mu);
 358                 if (!sum)
 359                         break;
 360         }
 361 }
 362
 363 static int input_mt_set_matrix(struct input_mt *mt,
 364                                const struct input_mt_pos *pos, int num_pos,
 365                                int mu)
 366 {
 367         const struct input_mt_pos *p;
 368         struct input_mt_slot *s;
 369         int *w = mt->red;
 370         int x, y;
 371
 372         for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
 373                 if (!input_mt_is_active(s))
 374                         continue;
 375                 x = input_mt_get_value(s, ABS_MT_POSITION_X);
 376                 y = input_mt_get_value(s, ABS_MT_POSITION_Y);
 377                 for (p = pos; p != pos + num_pos; p++) {
 378                         int dx = x - p->x, dy = y - p->y;
 379                         *w++ = dx * dx + dy * dy - mu;
 380                 }
 381         }
 382
 383         return w - mt->red;
 384 }
 385
 386 static void input_mt_set_slots(struct input_mt *mt,
 387                                int *slots, int num_pos)
 388 {
 389         struct input_mt_slot *s;
 390         int *w = mt->red, j;
 391
 392         for (j = 0; j != num_pos; j++)
 393                 slots[j] = -1;
 394
 395         for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
 396                 if (!input_mt_is_active(s))
 397                         continue;
 398
 399                 for (j = 0; j != num_pos; j++) {
 400                         if (w[j] < 0) {
 401                                 slots[j] = s - mt->slots;
 402                                 break;
 403                         }
 404                 }
 405
 406                 w += num_pos;
 407         }
 408
 409         for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
 410                 if (input_mt_is_active(s))
 411                         continue;
 412
 413                 for (j = 0; j != num_pos; j++) {
 414                         if (slots[j] < 0) {
 415                                 slots[j] = s - mt->slots;
 416                                 break;
 417                         }
 418                 }
 419         }
 420 }
 421
 422 /**
 423  * input_mt_assign_slots() - perform a best-match assignment
 424  * @dev: input device with allocated MT slots
 425  * @slots: the slot assignment to be filled
 426  * @pos: the position array to match
 427  * @num_pos: number of positions
 428  * @dmax: maximum ABS_MT_POSITION displacement (zero for infinite)
 429  *
 430  * Performs a best match against the current contacts and returns
 431  * the slot assignment list. New contacts are assigned to unused
 432  * slots.
 433  *
 434  * The assignments are balanced so that all coordinate displacements are
 435  * below the euclidian distance dmax. If no such assignment can be found,
 436  * some contacts are assigned to unused slots.
 437  *
 438  * Returns zero on success, or negative error in case of failure.
 439  */
 440 int input_mt_assign_slots(struct input_dev *dev, int *slots,
 441                           const struct input_mt_pos *pos, int num_pos,
 442                           int dmax)
 443 {
 444         struct input_mt *mt = dev->mt;
 445         int mu = 2 * dmax * dmax;
 446         int nrc;
 447
 448         if (!mt || !mt->red)
 449                 return -ENXIO;
 450         if (num_pos > mt->num_slots)
 451                 return -EINVAL;
 452         if (num_pos < 1)
 453                 return 0;
 454
 455         nrc = input_mt_set_matrix(mt, pos, num_pos, mu);
 456         find_reduced_matrix(mt->red, num_pos, nrc / num_pos, nrc, mu);
 457         input_mt_set_slots(mt, slots, num_pos);
 458
 459         return 0;
 460 }
 461 EXPORT_SYMBOL(input_mt_assign_slots);
 462
 463 /**
 464  * input_mt_get_slot_by_key() - return slot matching key
 465  * @dev: input device with allocated MT slots
 466  * @key: the key of the sought slot
 467  *
 468  * Returns the slot of the given key, if it exists, otherwise
 469  * set the key on the first unused slot and return.
 470  *
 471  * If no available slot can be found, -1 is returned.
 472  * Note that for this function to work properly, input_mt_sync_frame() has
 473  * to be called at each frame.
 474  */
 475 int input_mt_get_slot_by_key(struct input_dev *dev, int key)
 476 {
 477         struct input_mt *mt = dev->mt;
 478         struct input_mt_slot *s;
 479
 480         if (!mt)
 481                 return -1;
 482
 483         for (s = mt->slots; s != mt->slots + mt->num_slots; s++)
 484                 if (input_mt_is_active(s) && s->key == key)
 485                         return s - mt->slots;
 486
 487         for (s = mt->slots; s != mt->slots + mt->num_slots; s++)
 488                 if (!input_mt_is_active(s) && !input_mt_is_used(mt, s)) {
 489                         s->key = key;
 490                         return s - mt->slots;
 491                 }
 492
 493         return -1;
 494 }
 495 EXPORT_SYMBOL(input_mt_get_slot_by_key);