linux/drivers/input/ff-memless.c
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   1/*
   2 *  Force feedback support for memoryless devices
   3 *
   4 *  Copyright (c) 2006 Anssi Hannula <anssi.hannula@gmail.com>
   5 *  Copyright (c) 2006 Dmitry Torokhov <dtor@mail.ru>
   6 */
   7
   8/*
   9 * This program is free software; you can redistribute it and/or modify
  10 * it under the terms of the GNU General Public License as published by
  11 * the Free Software Foundation; either version 2 of the License, or
  12 * (at your option) any later version.
  13 *
  14 * This program is distributed in the hope that it will be useful,
  15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 * GNU General Public License for more details.
  18 *
  19 * You should have received a copy of the GNU General Public License
  20 * along with this program; if not, write to the Free Software
  21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  22 */
  23
  24/* #define DEBUG */
  25
  26#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  27
  28#include <linux/slab.h>
  29#include <linux/input.h>
  30#include <linux/module.h>
  31#include <linux/mutex.h>
  32#include <linux/spinlock.h>
  33#include <linux/jiffies.h>
  34#include <linux/fixp-arith.h>
  35
  36MODULE_LICENSE("GPL");
  37MODULE_AUTHOR("Anssi Hannula <anssi.hannula@gmail.com>");
  38MODULE_DESCRIPTION("Force feedback support for memoryless devices");
  39
  40/* Number of effects handled with memoryless devices */
  41#define FF_MEMLESS_EFFECTS      16
  42
  43/* Envelope update interval in ms */
  44#define FF_ENVELOPE_INTERVAL    50
  45
  46#define FF_EFFECT_STARTED       0
  47#define FF_EFFECT_PLAYING       1
  48#define FF_EFFECT_ABORTING      2
  49
  50struct ml_effect_state {
  51        struct ff_effect *effect;
  52        unsigned long flags;    /* effect state (STARTED, PLAYING, etc) */
  53        int count;              /* loop count of the effect */
  54        unsigned long play_at;  /* start time */
  55        unsigned long stop_at;  /* stop time */
  56        unsigned long adj_at;   /* last time the effect was sent */
  57};
  58
  59struct ml_device {
  60        void *private;
  61        struct ml_effect_state states[FF_MEMLESS_EFFECTS];
  62        int gain;
  63        struct timer_list timer;
  64        struct input_dev *dev;
  65
  66        int (*play_effect)(struct input_dev *dev, void *data,
  67                           struct ff_effect *effect);
  68};
  69
  70static const struct ff_envelope *get_envelope(const struct ff_effect *effect)
  71{
  72        static const struct ff_envelope empty_envelope;
  73
  74        switch (effect->type) {
  75        case FF_PERIODIC:
  76                return &effect->u.periodic.envelope;
  77
  78        case FF_CONSTANT:
  79                return &effect->u.constant.envelope;
  80
  81        default:
  82                return &empty_envelope;
  83        }
  84}
  85
  86/*
  87 * Check for the next time envelope requires an update on memoryless devices
  88 */
  89static unsigned long calculate_next_time(struct ml_effect_state *state)
  90{
  91        const struct ff_envelope *envelope = get_envelope(state->effect);
  92        unsigned long attack_stop, fade_start, next_fade;
  93
  94        if (envelope->attack_length) {
  95                attack_stop = state->play_at +
  96                        msecs_to_jiffies(envelope->attack_length);
  97                if (time_before(state->adj_at, attack_stop))
  98                        return state->adj_at +
  99                                        msecs_to_jiffies(FF_ENVELOPE_INTERVAL);
 100        }
 101
 102        if (state->effect->replay.length) {
 103                if (envelope->fade_length) {
 104                        /* check when fading should start */
 105                        fade_start = state->stop_at -
 106                                        msecs_to_jiffies(envelope->fade_length);
 107
 108                        if (time_before(state->adj_at, fade_start))
 109                                return fade_start;
 110
 111                        /* already fading, advance to next checkpoint */
 112                        next_fade = state->adj_at +
 113                                        msecs_to_jiffies(FF_ENVELOPE_INTERVAL);
 114                        if (time_before(next_fade, state->stop_at))
 115                                return next_fade;
 116                }
 117
 118                return state->stop_at;
 119        }
 120
 121        return state->play_at;
 122}
 123
 124static void ml_schedule_timer(struct ml_device *ml)
 125{
 126        struct ml_effect_state *state;
 127        unsigned long now = jiffies;
 128        unsigned long earliest = 0;
 129        unsigned long next_at;
 130        int events = 0;
 131        int i;
 132
 133        pr_debug("calculating next timer\n");
 134
 135        for (i = 0; i < FF_MEMLESS_EFFECTS; i++) {
 136
 137                state = &ml->states[i];
 138
 139                if (!test_bit(FF_EFFECT_STARTED, &state->flags))
 140                        continue;
 141
 142                if (test_bit(FF_EFFECT_PLAYING, &state->flags))
 143                        next_at = calculate_next_time(state);
 144                else
 145                        next_at = state->play_at;
 146
 147                if (time_before_eq(now, next_at) &&
 148                    (++events == 1 || time_before(next_at, earliest)))
 149                        earliest = next_at;
 150        }
 151
 152        if (!events) {
 153                pr_debug("no actions\n");
 154                del_timer(&ml->timer);
 155        } else {
 156                pr_debug("timer set\n");
 157                mod_timer(&ml->timer, earliest);
 158        }
 159}
 160
 161/*
 162 * Apply an envelope to a value
 163 */
 164static int apply_envelope(struct ml_effect_state *state, int value,
 165                          struct ff_envelope *envelope)
 166{
 167        struct ff_effect *effect = state->effect;
 168        unsigned long now = jiffies;
 169        int time_from_level;
 170        int time_of_envelope;
 171        int envelope_level;
 172        int difference;
 173
 174        if (envelope->attack_length &&
 175            time_before(now,
 176                        state->play_at + msecs_to_jiffies(envelope->attack_length))) {
 177                pr_debug("value = 0x%x, attack_level = 0x%x\n",
 178                         value, envelope->attack_level);
 179                time_from_level = jiffies_to_msecs(now - state->play_at);
 180                time_of_envelope = envelope->attack_length;
 181                envelope_level = min_t(u16, envelope->attack_level, 0x7fff);
 182
 183        } else if (envelope->fade_length && effect->replay.length &&
 184                   time_after(now,
 185                              state->stop_at - msecs_to_jiffies(envelope->fade_length)) &&
 186                   time_before(now, state->stop_at)) {
 187                time_from_level = jiffies_to_msecs(state->stop_at - now);
 188                time_of_envelope = envelope->fade_length;
 189                envelope_level = min_t(u16, envelope->fade_level, 0x7fff);
 190        } else
 191                return value;
 192
 193        difference = abs(value) - envelope_level;
 194
 195        pr_debug("difference = %d\n", difference);
 196        pr_debug("time_from_level = 0x%x\n", time_from_level);
 197        pr_debug("time_of_envelope = 0x%x\n", time_of_envelope);
 198
 199        difference = difference * time_from_level / time_of_envelope;
 200
 201        pr_debug("difference = %d\n", difference);
 202
 203        return value < 0 ?
 204                -(difference + envelope_level) : (difference + envelope_level);
 205}
 206
 207/*
 208 * Return the type the effect has to be converted into (memless devices)
 209 */
 210static int get_compatible_type(struct ff_device *ff, int effect_type)
 211{
 212
 213        if (test_bit(effect_type, ff->ffbit))
 214                return effect_type;
 215
 216        if (effect_type == FF_PERIODIC && test_bit(FF_RUMBLE, ff->ffbit))
 217                return FF_RUMBLE;
 218
 219        pr_err("invalid type in get_compatible_type()\n");
 220
 221        return 0;
 222}
 223
 224/*
 225 * Only left/right direction should be used (under/over 0x8000) for
 226 * forward/reverse motor direction (to keep calculation fast & simple).
 227 */
 228static u16 ml_calculate_direction(u16 direction, u16 force,
 229                                  u16 new_direction, u16 new_force)
 230{
 231        if (!force)
 232                return new_direction;
 233        if (!new_force)
 234                return direction;
 235        return (((u32)(direction >> 1) * force +
 236                 (new_direction >> 1) * new_force) /
 237                (force + new_force)) << 1;
 238}
 239
 240/*
 241 * Combine two effects and apply gain.
 242 */
 243static void ml_combine_effects(struct ff_effect *effect,
 244                               struct ml_effect_state *state,
 245                               int gain)
 246{
 247        struct ff_effect *new = state->effect;
 248        unsigned int strong, weak, i;
 249        int x, y;
 250        fixp_t level;
 251
 252        switch (new->type) {
 253        case FF_CONSTANT:
 254                i = new->direction * 360 / 0xffff;
 255                level = fixp_new16(apply_envelope(state,
 256                                        new->u.constant.level,
 257                                        &new->u.constant.envelope));
 258                x = fixp_mult(fixp_sin(i), level) * gain / 0xffff;
 259                y = fixp_mult(-fixp_cos(i), level) * gain / 0xffff;
 260                /*
 261                 * here we abuse ff_ramp to hold x and y of constant force
 262                 * If in future any driver wants something else than x and y
 263                 * in s8, this should be changed to something more generic
 264                 */
 265                effect->u.ramp.start_level =
 266                        clamp_val(effect->u.ramp.start_level + x, -0x80, 0x7f);
 267                effect->u.ramp.end_level =
 268                        clamp_val(effect->u.ramp.end_level + y, -0x80, 0x7f);
 269                break;
 270
 271        case FF_RUMBLE:
 272                strong = (u32)new->u.rumble.strong_magnitude * gain / 0xffff;
 273                weak = (u32)new->u.rumble.weak_magnitude * gain / 0xffff;
 274
 275                if (effect->u.rumble.strong_magnitude + strong)
 276                        effect->direction = ml_calculate_direction(
 277                                effect->direction,
 278                                effect->u.rumble.strong_magnitude,
 279                                new->direction, strong);
 280                else if (effect->u.rumble.weak_magnitude + weak)
 281                        effect->direction = ml_calculate_direction(
 282                                effect->direction,
 283                                effect->u.rumble.weak_magnitude,
 284                                new->direction, weak);
 285                else
 286                        effect->direction = 0;
 287                effect->u.rumble.strong_magnitude =
 288                        min(strong + effect->u.rumble.strong_magnitude,
 289                            0xffffU);
 290                effect->u.rumble.weak_magnitude =
 291                        min(weak + effect->u.rumble.weak_magnitude, 0xffffU);
 292                break;
 293
 294        case FF_PERIODIC:
 295                i = apply_envelope(state, abs(new->u.periodic.magnitude),
 296                                   &new->u.periodic.envelope);
 297
 298                /* here we also scale it 0x7fff => 0xffff */
 299                i = i * gain / 0x7fff;
 300
 301                if (effect->u.rumble.strong_magnitude + i)
 302                        effect->direction = ml_calculate_direction(
 303                                effect->direction,
 304                                effect->u.rumble.strong_magnitude,
 305                                new->direction, i);
 306                else
 307                        effect->direction = 0;
 308                effect->u.rumble.strong_magnitude =
 309                        min(i + effect->u.rumble.strong_magnitude, 0xffffU);
 310                effect->u.rumble.weak_magnitude =
 311                        min(i + effect->u.rumble.weak_magnitude, 0xffffU);
 312                break;
 313
 314        default:
 315                pr_err("invalid type in ml_combine_effects()\n");
 316                break;
 317        }
 318
 319}
 320
 321
 322/*
 323 * Because memoryless devices have only one effect per effect type active
 324 * at one time we have to combine multiple effects into one
 325 */
 326static int ml_get_combo_effect(struct ml_device *ml,
 327                               unsigned long *effect_handled,
 328                               struct ff_effect *combo_effect)
 329{
 330        struct ff_effect *effect;
 331        struct ml_effect_state *state;
 332        int effect_type;
 333        int i;
 334
 335        memset(combo_effect, 0, sizeof(struct ff_effect));
 336
 337        for (i = 0; i < FF_MEMLESS_EFFECTS; i++) {
 338                if (__test_and_set_bit(i, effect_handled))
 339                        continue;
 340
 341                state = &ml->states[i];
 342                effect = state->effect;
 343
 344                if (!test_bit(FF_EFFECT_STARTED, &state->flags))
 345                        continue;
 346
 347                if (time_before(jiffies, state->play_at))
 348                        continue;
 349
 350                /*
 351                 * here we have started effects that are either
 352                 * currently playing (and may need be aborted)
 353                 * or need to start playing.
 354                 */
 355                effect_type = get_compatible_type(ml->dev->ff, effect->type);
 356                if (combo_effect->type != effect_type) {
 357                        if (combo_effect->type != 0) {
 358                                __clear_bit(i, effect_handled);
 359                                continue;
 360                        }
 361                        combo_effect->type = effect_type;
 362                }
 363
 364                if (__test_and_clear_bit(FF_EFFECT_ABORTING, &state->flags)) {
 365                        __clear_bit(FF_EFFECT_PLAYING, &state->flags);
 366                        __clear_bit(FF_EFFECT_STARTED, &state->flags);
 367                } else if (effect->replay.length &&
 368                           time_after_eq(jiffies, state->stop_at)) {
 369
 370                        __clear_bit(FF_EFFECT_PLAYING, &state->flags);
 371
 372                        if (--state->count <= 0) {
 373                                __clear_bit(FF_EFFECT_STARTED, &state->flags);
 374                        } else {
 375                                state->play_at = jiffies +
 376                                        msecs_to_jiffies(effect->replay.delay);
 377                                state->stop_at = state->play_at +
 378                                        msecs_to_jiffies(effect->replay.length);
 379                        }
 380                } else {
 381                        __set_bit(FF_EFFECT_PLAYING, &state->flags);
 382                        state->adj_at = jiffies;
 383                        ml_combine_effects(combo_effect, state, ml->gain);
 384                }
 385        }
 386
 387        return combo_effect->type != 0;
 388}
 389
 390static void ml_play_effects(struct ml_device *ml)
 391{
 392        struct ff_effect effect;
 393        DECLARE_BITMAP(handled_bm, FF_MEMLESS_EFFECTS);
 394
 395        memset(handled_bm, 0, sizeof(handled_bm));
 396
 397        while (ml_get_combo_effect(ml, handled_bm, &effect))
 398                ml->play_effect(ml->dev, ml->private, &effect);
 399
 400        ml_schedule_timer(ml);
 401}
 402
 403static void ml_effect_timer(unsigned long timer_data)
 404{
 405        struct input_dev *dev = (struct input_dev *)timer_data;
 406        struct ml_device *ml = dev->ff->private;
 407        unsigned long flags;
 408
 409        pr_debug("timer: updating effects\n");
 410
 411        spin_lock_irqsave(&dev->event_lock, flags);
 412        ml_play_effects(ml);
 413        spin_unlock_irqrestore(&dev->event_lock, flags);
 414}
 415
 416/*
 417 * Sets requested gain for FF effects. Called with dev->event_lock held.
 418 */
 419static void ml_ff_set_gain(struct input_dev *dev, u16 gain)
 420{
 421        struct ml_device *ml = dev->ff->private;
 422        int i;
 423
 424        ml->gain = gain;
 425
 426        for (i = 0; i < FF_MEMLESS_EFFECTS; i++)
 427                __clear_bit(FF_EFFECT_PLAYING, &ml->states[i].flags);
 428
 429        ml_play_effects(ml);
 430}
 431
 432/*
 433 * Start/stop specified FF effect. Called with dev->event_lock held.
 434 */
 435static int ml_ff_playback(struct input_dev *dev, int effect_id, int value)
 436{
 437        struct ml_device *ml = dev->ff->private;
 438        struct ml_effect_state *state = &ml->states[effect_id];
 439
 440        if (value > 0) {
 441                pr_debug("initiated play\n");
 442
 443                __set_bit(FF_EFFECT_STARTED, &state->flags);
 444                state->count = value;
 445                state->play_at = jiffies +
 446                                 msecs_to_jiffies(state->effect->replay.delay);
 447                state->stop_at = state->play_at +
 448                                 msecs_to_jiffies(state->effect->replay.length);
 449                state->adj_at = state->play_at;
 450
 451        } else {
 452                pr_debug("initiated stop\n");
 453
 454                if (test_bit(FF_EFFECT_PLAYING, &state->flags))
 455                        __set_bit(FF_EFFECT_ABORTING, &state->flags);
 456                else
 457                        __clear_bit(FF_EFFECT_STARTED, &state->flags);
 458        }
 459
 460        ml_play_effects(ml);
 461
 462        return 0;
 463}
 464
 465static int ml_ff_upload(struct input_dev *dev,
 466                        struct ff_effect *effect, struct ff_effect *old)
 467{
 468        struct ml_device *ml = dev->ff->private;
 469        struct ml_effect_state *state = &ml->states[effect->id];
 470
 471        spin_lock_irq(&dev->event_lock);
 472
 473        if (test_bit(FF_EFFECT_STARTED, &state->flags)) {
 474                __clear_bit(FF_EFFECT_PLAYING, &state->flags);
 475                state->play_at = jiffies +
 476                                 msecs_to_jiffies(state->effect->replay.delay);
 477                state->stop_at = state->play_at +
 478                                 msecs_to_jiffies(state->effect->replay.length);
 479                state->adj_at = state->play_at;
 480                ml_schedule_timer(ml);
 481        }
 482
 483        spin_unlock_irq(&dev->event_lock);
 484
 485        return 0;
 486}
 487
 488static void ml_ff_destroy(struct ff_device *ff)
 489{
 490        struct ml_device *ml = ff->private;
 491
 492        kfree(ml->private);
 493}
 494
 495/**
 496 * input_ff_create_memless() - create memoryless force-feedback device
 497 * @dev: input device supporting force-feedback
 498 * @data: driver-specific data to be passed into @play_effect
 499 * @play_effect: driver-specific method for playing FF effect
 500 */
 501int input_ff_create_memless(struct input_dev *dev, void *data,
 502                int (*play_effect)(struct input_dev *, void *, struct ff_effect *))
 503{
 504        struct ml_device *ml;
 505        struct ff_device *ff;
 506        int error;
 507        int i;
 508
 509        ml = kzalloc(sizeof(struct ml_device), GFP_KERNEL);
 510        if (!ml)
 511                return -ENOMEM;
 512
 513        ml->dev = dev;
 514        ml->private = data;
 515        ml->play_effect = play_effect;
 516        ml->gain = 0xffff;
 517        setup_timer(&ml->timer, ml_effect_timer, (unsigned long)dev);
 518
 519        set_bit(FF_GAIN, dev->ffbit);
 520
 521        error = input_ff_create(dev, FF_MEMLESS_EFFECTS);
 522        if (error) {
 523                kfree(ml);
 524                return error;
 525        }
 526
 527        ff = dev->ff;
 528        ff->private = ml;
 529        ff->upload = ml_ff_upload;
 530        ff->playback = ml_ff_playback;
 531        ff->set_gain = ml_ff_set_gain;
 532        ff->destroy = ml_ff_destroy;
 533
 534        /* we can emulate periodic effects with RUMBLE */
 535        if (test_bit(FF_RUMBLE, ff->ffbit)) {
 536                set_bit(FF_PERIODIC, dev->ffbit);
 537                set_bit(FF_SINE, dev->ffbit);
 538                set_bit(FF_TRIANGLE, dev->ffbit);
 539                set_bit(FF_SQUARE, dev->ffbit);
 540        }
 541
 542        for (i = 0; i < FF_MEMLESS_EFFECTS; i++)
 543                ml->states[i].effect = &ff->effects[i];
 544
 545        return 0;
 546}
 547EXPORT_SYMBOL_GPL(input_ff_create_memless);
 548
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