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_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 'unused' */
  92        for (i = 0; i < num_slots; i++)
  93                input_mt_set_value(&mt->slots[i], ABS_MT_TRACKING_ID, -1);
  94
  95        dev->mt = mt;
  96        return 0;
  97err_mem:
  98        kfree(mt);
  99        return -ENOMEM;
 100}
 101EXPORT_SYMBOL(input_mt_init_slots);
 102
 103/**
 104 * input_mt_destroy_slots() - frees the MT slots of the input device
 105 * @dev: input device with allocated MT slots
 106 *
 107 * This function is only needed in error path as the input core will
 108 * automatically free the MT slots when the device is destroyed.
 109 */
 110void input_mt_destroy_slots(struct input_dev *dev)
 111{
 112        if (dev->mt) {
 113                kfree(dev->mt->red);
 114                kfree(dev->mt);
 115        }
 116        dev->mt = NULL;
 117}
 118EXPORT_SYMBOL(input_mt_destroy_slots);
 119
 120/**
 121 * input_mt_report_slot_state() - report contact state
 122 * @dev: input device with allocated MT slots
 123 * @tool_type: the tool type to use in this slot
 124 * @active: true if contact is active, false otherwise
 125 *
 126 * Reports a contact via ABS_MT_TRACKING_ID, and optionally
 127 * ABS_MT_TOOL_TYPE. If active is true and the slot is currently
 128 * inactive, or if the tool type is changed, a new tracking id is
 129 * assigned to the slot. The tool type is only reported if the
 130 * corresponding absbit field is set.
 131 */
 132void input_mt_report_slot_state(struct input_dev *dev,
 133                                unsigned int tool_type, bool active)
 134{
 135        struct input_mt *mt = dev->mt;
 136        struct input_mt_slot *slot;
 137        int id;
 138
 139        if (!mt)
 140                return;
 141
 142        slot = &mt->slots[mt->slot];
 143        slot->frame = mt->frame;
 144
 145        if (!active) {
 146                input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
 147                return;
 148        }
 149
 150        id = input_mt_get_value(slot, ABS_MT_TRACKING_ID);
 151        if (id < 0 || input_mt_get_value(slot, ABS_MT_TOOL_TYPE) != tool_type)
 152                id = input_mt_new_trkid(mt);
 153
 154        input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, id);
 155        input_event(dev, EV_ABS, ABS_MT_TOOL_TYPE, tool_type);
 156}
 157EXPORT_SYMBOL(input_mt_report_slot_state);
 158
 159/**
 160 * input_mt_report_finger_count() - report contact count
 161 * @dev: input device with allocated MT slots
 162 * @count: the number of contacts
 163 *
 164 * Reports the contact count via BTN_TOOL_FINGER, BTN_TOOL_DOUBLETAP,
 165 * BTN_TOOL_TRIPLETAP and BTN_TOOL_QUADTAP.
 166 *
 167 * The input core ensures only the KEY events already setup for
 168 * this device will produce output.
 169 */
 170void input_mt_report_finger_count(struct input_dev *dev, int count)
 171{
 172        input_event(dev, EV_KEY, BTN_TOOL_FINGER, count == 1);
 173        input_event(dev, EV_KEY, BTN_TOOL_DOUBLETAP, count == 2);
 174        input_event(dev, EV_KEY, BTN_TOOL_TRIPLETAP, count == 3);
 175        input_event(dev, EV_KEY, BTN_TOOL_QUADTAP, count == 4);
 176        input_event(dev, EV_KEY, BTN_TOOL_QUINTTAP, count == 5);
 177}
 178EXPORT_SYMBOL(input_mt_report_finger_count);
 179
 180/**
 181 * input_mt_report_pointer_emulation() - common pointer emulation
 182 * @dev: input device with allocated MT slots
 183 * @use_count: report number of active contacts as finger count
 184 *
 185 * Performs legacy pointer emulation via BTN_TOUCH, ABS_X, ABS_Y and
 186 * ABS_PRESSURE. Touchpad finger count is emulated if use_count is true.
 187 *
 188 * The input core ensures only the KEY and ABS axes already setup for
 189 * this device will produce output.
 190 */
 191void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)
 192{
 193        struct input_mt *mt = dev->mt;
 194        struct input_mt_slot *oldest;
 195        int oldid, count, i;
 196
 197        if (!mt)
 198                return;
 199
 200        oldest = NULL;
 201        oldid = mt->trkid;
 202        count = 0;
 203
 204        for (i = 0; i < mt->num_slots; ++i) {
 205                struct input_mt_slot *ps = &mt->slots[i];
 206                int id = input_mt_get_value(ps, ABS_MT_TRACKING_ID);
 207
 208                if (id < 0)
 209                        continue;
 210                if ((id - oldid) & TRKID_SGN) {
 211                        oldest = ps;
 212                        oldid = id;
 213                }
 214                count++;
 215        }
 216
 217        input_event(dev, EV_KEY, BTN_TOUCH, count > 0);
 218        if (use_count)
 219                input_mt_report_finger_count(dev, count);
 220
 221        if (oldest) {
 222                int x = input_mt_get_value(oldest, ABS_MT_POSITION_X);
 223                int y = input_mt_get_value(oldest, ABS_MT_POSITION_Y);
 224
 225                input_event(dev, EV_ABS, ABS_X, x);
 226                input_event(dev, EV_ABS, ABS_Y, y);
 227
 228                if (test_bit(ABS_MT_PRESSURE, dev->absbit)) {
 229                        int p = input_mt_get_value(oldest, ABS_MT_PRESSURE);
 230                        input_event(dev, EV_ABS, ABS_PRESSURE, p);
 231                }
 232        } else {
 233                if (test_bit(ABS_MT_PRESSURE, dev->absbit))
 234                        input_event(dev, EV_ABS, ABS_PRESSURE, 0);
 235        }
 236}
 237EXPORT_SYMBOL(input_mt_report_pointer_emulation);
 238
 239/**
 240 * input_mt_sync_frame() - synchronize mt frame
 241 * @dev: input device with allocated MT slots
 242 *
 243 * Close the frame and prepare the internal state for a new one.
 244 * Depending on the flags, marks unused slots as inactive and performs
 245 * pointer emulation.
 246 */
 247void input_mt_sync_frame(struct input_dev *dev)
 248{
 249        struct input_mt *mt = dev->mt;
 250        struct input_mt_slot *s;
 251        bool use_count = false;
 252
 253        if (!mt)
 254                return;
 255
 256        if (mt->flags & INPUT_MT_DROP_UNUSED) {
 257                for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
 258                        if (input_mt_is_used(mt, s))
 259                                continue;
 260                        input_mt_slot(dev, s - mt->slots);
 261                        input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
 262                }
 263        }
 264
 265        if ((mt->flags & INPUT_MT_POINTER) && !(mt->flags & INPUT_MT_SEMI_MT))
 266                use_count = true;
 267
 268        input_mt_report_pointer_emulation(dev, use_count);
 269
 270        mt->frame++;
 271}
 272EXPORT_SYMBOL(input_mt_sync_frame);
 273
 274static int adjust_dual(int *begin, int step, int *end, int eq)
 275{
 276        int f, *p, s, c;
 277
 278        if (begin == end)
 279                return 0;
 280
 281        f = *begin;
 282        p = begin + step;
 283        s = p == end ? f + 1 : *p;
 284
 285        for (; p != end; p += step)
 286                if (*p < f)
 287                        s = f, f = *p;
 288                else if (*p < s)
 289                        s = *p;
 290
 291        c = (f + s + 1) / 2;
 292        if (c == 0 || (c > 0 && !eq))
 293                return 0;
 294        if (s < 0)
 295                c *= 2;
 296
 297        for (p = begin; p != end; p += step)
 298                *p -= c;
 299
 300        return (c < s && s <= 0) || (f >= 0 && f < c);
 301}
 302
 303static void find_reduced_matrix(int *w, int nr, int nc, int nrc)
 304{
 305        int i, k, sum;
 306
 307        for (k = 0; k < nrc; k++) {
 308                for (i = 0; i < nr; i++)
 309                        adjust_dual(w + i, nr, w + i + nrc, nr <= nc);
 310                sum = 0;
 311                for (i = 0; i < nrc; i += nr)
 312                        sum += adjust_dual(w + i, 1, w + i + nr, nc <= nr);
 313                if (!sum)
 314                        break;
 315        }
 316}
 317
 318static int input_mt_set_matrix(struct input_mt *mt,
 319                               const struct input_mt_pos *pos, int num_pos)
 320{
 321        const struct input_mt_pos *p;
 322        struct input_mt_slot *s;
 323        int *w = mt->red;
 324        int x, y;
 325
 326        for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
 327                if (!input_mt_is_active(s))
 328                        continue;
 329                x = input_mt_get_value(s, ABS_MT_POSITION_X);
 330                y = input_mt_get_value(s, ABS_MT_POSITION_Y);
 331                for (p = pos; p != pos + num_pos; p++) {
 332                        int dx = x - p->x, dy = y - p->y;
 333                        *w++ = dx * dx + dy * dy;
 334                }
 335        }
 336
 337        return w - mt->red;
 338}
 339
 340static void input_mt_set_slots(struct input_mt *mt,
 341                               int *slots, int num_pos)
 342{
 343        struct input_mt_slot *s;
 344        int *w = mt->red, *p;
 345
 346        for (p = slots; p != slots + num_pos; p++)
 347                *p = -1;
 348
 349        for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
 350                if (!input_mt_is_active(s))
 351                        continue;
 352                for (p = slots; p != slots + num_pos; p++)
 353                        if (*w++ < 0)
 354                                *p = s - mt->slots;
 355        }
 356
 357        for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
 358                if (input_mt_is_active(s))
 359                        continue;
 360                for (p = slots; p != slots + num_pos; p++)
 361                        if (*p < 0) {
 362                                *p = s - mt->slots;
 363                                break;
 364                        }
 365        }
 366}
 367
 368/**
 369 * input_mt_assign_slots() - perform a best-match assignment
 370 * @dev: input device with allocated MT slots
 371 * @slots: the slot assignment to be filled
 372 * @pos: the position array to match
 373 * @num_pos: number of positions
 374 *
 375 * Performs a best match against the current contacts and returns
 376 * the slot assignment list. New contacts are assigned to unused
 377 * slots.
 378 *
 379 * Returns zero on success, or negative error in case of failure.
 380 */
 381int input_mt_assign_slots(struct input_dev *dev, int *slots,
 382                          const struct input_mt_pos *pos, int num_pos)
 383{
 384        struct input_mt *mt = dev->mt;
 385        int nrc;
 386
 387        if (!mt || !mt->red)
 388                return -ENXIO;
 389        if (num_pos > mt->num_slots)
 390                return -EINVAL;
 391        if (num_pos < 1)
 392                return 0;
 393
 394        nrc = input_mt_set_matrix(mt, pos, num_pos);
 395        find_reduced_matrix(mt->red, num_pos, nrc / num_pos, nrc);
 396        input_mt_set_slots(mt, slots, num_pos);
 397
 398        return 0;
 399}
 400EXPORT_SYMBOL(input_mt_assign_slots);
 401
 402/**
 403 * input_mt_get_slot_by_key() - return slot matching key
 404 * @dev: input device with allocated MT slots
 405 * @key: the key of the sought slot
 406 *
 407 * Returns the slot of the given key, if it exists, otherwise
 408 * set the key on the first unused slot and return.
 409 *
 410 * If no available slot can be found, -1 is returned.
 411 */
 412int input_mt_get_slot_by_key(struct input_dev *dev, int key)
 413{
 414        struct input_mt *mt = dev->mt;
 415        struct input_mt_slot *s;
 416
 417        if (!mt)
 418                return -1;
 419
 420        for (s = mt->slots; s != mt->slots + mt->num_slots; s++)
 421                if (input_mt_is_active(s) && s->key == key)
 422                        return s - mt->slots;
 423
 424        for (s = mt->slots; s != mt->slots + mt->num_slots; s++)
 425                if (!input_mt_is_active(s)) {
 426                        s->key = key;
 427                        return s - mt->slots;
 428                }
 429
 430        return -1;
 431}
 432EXPORT_SYMBOL(input_mt_get_slot_by_key);
 433
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