drivers/input/ff-memless.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Force feedback support for memoryless devices
   4  *
   5  *  Copyright (c) 2006 Anssi Hannula <anssi.hannula@gmail.com>
   6  *  Copyright (c) 2006 Dmitry Torokhov <dtor@mail.ru>
   7  */
   8
   9 /* #define DEBUG */
  10
  11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  12
  13 #include <linux/slab.h>
  14 #include <linux/input.h>
  15 #include <linux/module.h>
  16 #include <linux/mutex.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/jiffies.h>
  19 #include <linux/fixp-arith.h>
  20
  21 MODULE_LICENSE("GPL");
  22 MODULE_AUTHOR("Anssi Hannula <anssi.hannula@gmail.com>");
  23 MODULE_DESCRIPTION("Force feedback support for memoryless devices");
  24
  25 /* Number of effects handled with memoryless devices */
  26 #define FF_MEMLESS_EFFECTS      16
  27
  28 /* Envelope update interval in ms */
  29 #define FF_ENVELOPE_INTERVAL    50
  30
  31 #define FF_EFFECT_STARTED       0
  32 #define FF_EFFECT_PLAYING       1
  33 #define FF_EFFECT_ABORTING      2
  34
  35 struct ml_effect_state {
  36         struct ff_effect *effect;
  37         unsigned long flags;    /* effect state (STARTED, PLAYING, etc) */
  38         int count;              /* loop count of the effect */
  39         unsigned long play_at;  /* start time */
  40         unsigned long stop_at;  /* stop time */
  41         unsigned long adj_at;   /* last time the effect was sent */
  42 };
  43
  44 struct ml_device {
  45         void *private;
  46         struct ml_effect_state states[FF_MEMLESS_EFFECTS];
  47         int gain;
  48         struct timer_list timer;
  49         struct input_dev *dev;
  50
  51         int (*play_effect)(struct input_dev *dev, void *data,
  52                            struct ff_effect *effect);
  53 };
  54
  55 static const struct ff_envelope *get_envelope(const struct ff_effect *effect)
  56 {
  57         static const struct ff_envelope empty_envelope;
  58
  59         switch (effect->type) {
  60         case FF_PERIODIC:
  61                 return &effect->u.periodic.envelope;
  62
  63         case FF_CONSTANT:
  64                 return &effect->u.constant.envelope;
  65
  66         default:
  67                 return &empty_envelope;
  68         }
  69 }
  70
  71 /*
  72  * Check for the next time envelope requires an update on memoryless devices
  73  */
  74 static unsigned long calculate_next_time(struct ml_effect_state *state)
  75 {
  76         const struct ff_envelope *envelope = get_envelope(state->effect);
  77         unsigned long attack_stop, fade_start, next_fade;
  78
  79         if (envelope->attack_length) {
  80                 attack_stop = state->play_at +
  81                         msecs_to_jiffies(envelope->attack_length);
  82                 if (time_before(state->adj_at, attack_stop))
  83                         return state->adj_at +
  84                                         msecs_to_jiffies(FF_ENVELOPE_INTERVAL);
  85         }
  86
  87         if (state->effect->replay.length) {
  88                 if (envelope->fade_length) {
  89                         /* check when fading should start */
  90                         fade_start = state->stop_at -
  91                                         msecs_to_jiffies(envelope->fade_length);
  92
  93                         if (time_before(state->adj_at, fade_start))
  94                                 return fade_start;
  95
  96                         /* already fading, advance to next checkpoint */
  97                         next_fade = state->adj_at +
  98                                         msecs_to_jiffies(FF_ENVELOPE_INTERVAL);
  99                         if (time_before(next_fade, state->stop_at))
 100                                 return next_fade;
 101                 }
 102
 103                 return state->stop_at;
 104         }
 105
 106         return state->play_at;
 107 }
 108
 109 static void ml_schedule_timer(struct ml_device *ml)
 110 {
 111         struct ml_effect_state *state;
 112         unsigned long now = jiffies;
 113         unsigned long earliest = 0;
 114         unsigned long next_at;
 115         int events = 0;
 116         int i;
 117
 118         pr_debug("calculating next timer\n");
 119
 120         for (i = 0; i < FF_MEMLESS_EFFECTS; i++) {
 121
 122                 state = &ml->states[i];
 123
 124                 if (!test_bit(FF_EFFECT_STARTED, &state->flags))
 125                         continue;
 126
 127                 if (test_bit(FF_EFFECT_PLAYING, &state->flags))
 128                         next_at = calculate_next_time(state);
 129                 else
 130                         next_at = state->play_at;
 131
 132                 if (time_before_eq(now, next_at) &&
 133                     (++events == 1 || time_before(next_at, earliest)))
 134                         earliest = next_at;
 135         }
 136
 137         if (!events) {
 138                 pr_debug("no actions\n");
 139                 del_timer(&ml->timer);
 140         } else {
 141                 pr_debug("timer set\n");
 142                 mod_timer(&ml->timer, earliest);
 143         }
 144 }
 145
 146 /*
 147  * Apply an envelope to a value
 148  */
 149 static int apply_envelope(struct ml_effect_state *state, int value,
 150                           struct ff_envelope *envelope)
 151 {
 152         struct ff_effect *effect = state->effect;
 153         unsigned long now = jiffies;
 154         int time_from_level;
 155         int time_of_envelope;
 156         int envelope_level;
 157         int difference;
 158
 159         if (envelope->attack_length &&
 160             time_before(now,
 161                         state->play_at + msecs_to_jiffies(envelope->attack_length))) {
 162                 pr_debug("value = 0x%x, attack_level = 0x%x\n",
 163                          value, envelope->attack_level);
 164                 time_from_level = jiffies_to_msecs(now - state->play_at);
 165                 time_of_envelope = envelope->attack_length;
 166                 envelope_level = min_t(u16, envelope->attack_level, 0x7fff);
 167
 168         } else if (envelope->fade_length && effect->replay.length &&
 169                    time_after(now,
 170                               state->stop_at - msecs_to_jiffies(envelope->fade_length)) &&
 171                    time_before(now, state->stop_at)) {
 172                 time_from_level = jiffies_to_msecs(state->stop_at - now);
 173                 time_of_envelope = envelope->fade_length;
 174                 envelope_level = min_t(u16, envelope->fade_level, 0x7fff);
 175         } else
 176                 return value;
 177
 178         difference = abs(value) - envelope_level;
 179
 180         pr_debug("difference = %d\n", difference);
 181         pr_debug("time_from_level = 0x%x\n", time_from_level);
 182         pr_debug("time_of_envelope = 0x%x\n", time_of_envelope);
 183
 184         difference = difference * time_from_level / time_of_envelope;
 185
 186         pr_debug("difference = %d\n", difference);
 187
 188         return value < 0 ?
 189                 -(difference + envelope_level) : (difference + envelope_level);
 190 }
 191
 192 /*
 193  * Return the type the effect has to be converted into (memless devices)
 194  */
 195 static int get_compatible_type(struct ff_device *ff, int effect_type)
 196 {
 197
 198         if (test_bit(effect_type, ff->ffbit))
 199                 return effect_type;
 200
 201         if (effect_type == FF_PERIODIC && test_bit(FF_RUMBLE, ff->ffbit))
 202                 return FF_RUMBLE;
 203
 204         pr_err("invalid type in get_compatible_type()\n");
 205
 206         return 0;
 207 }
 208
 209 /*
 210  * Only left/right direction should be used (under/over 0x8000) for
 211  * forward/reverse motor direction (to keep calculation fast & simple).
 212  */
 213 static u16 ml_calculate_direction(u16 direction, u16 force,
 214                                   u16 new_direction, u16 new_force)
 215 {
 216         if (!force)
 217                 return new_direction;
 218         if (!new_force)
 219                 return direction;
 220         return (((u32)(direction >> 1) * force +
 221                  (new_direction >> 1) * new_force) /
 222                 (force + new_force)) << 1;
 223 }
 224
 225 #define FRAC_N 8
 226 static inline s16 fixp_new16(s16 a)
 227 {
 228         return ((s32)a) >> (16 - FRAC_N);
 229 }
 230
 231 static inline s16 fixp_mult(s16 a, s16 b)
 232 {
 233         a = ((s32)a * 0x100) / 0x7fff;
 234         return ((s32)(a * b)) >> FRAC_N;
 235 }
 236
 237 /*
 238  * Combine two effects and apply gain.
 239  */
 240 static void ml_combine_effects(struct ff_effect *effect,
 241                                struct ml_effect_state *state,
 242                                int gain)
 243 {
 244         struct ff_effect *new = state->effect;
 245         unsigned int strong, weak, i;
 246         int x, y;
 247         s16 level;
 248
 249         switch (new->type) {
 250         case FF_CONSTANT:
 251                 i = new->direction * 360 / 0xffff;
 252                 level = fixp_new16(apply_envelope(state,
 253                                         new->u.constant.level,
 254                                         &new->u.constant.envelope));
 255                 x = fixp_mult(fixp_sin16(i), level) * gain / 0xffff;
 256                 y = fixp_mult(-fixp_cos16(i), level) * gain / 0xffff;
 257                 /*
 258                  * here we abuse ff_ramp to hold x and y of constant force
 259                  * If in future any driver wants something else than x and y
 260                  * in s8, this should be changed to something more generic
 261                  */
 262                 effect->u.ramp.start_level =
 263                         clamp_val(effect->u.ramp.start_level + x, -0x80, 0x7f);
 264                 effect->u.ramp.end_level =
 265                         clamp_val(effect->u.ramp.end_level + y, -0x80, 0x7f);
 266                 break;
 267
 268         case FF_RUMBLE:
 269                 strong = (u32)new->u.rumble.strong_magnitude * gain / 0xffff;
 270                 weak = (u32)new->u.rumble.weak_magnitude * gain / 0xffff;
 271
 272                 if (effect->u.rumble.strong_magnitude + strong)
 273                         effect->direction = ml_calculate_direction(
 274                                 effect->direction,
 275                                 effect->u.rumble.strong_magnitude,
 276                                 new->direction, strong);
 277                 else if (effect->u.rumble.weak_magnitude + weak)
 278                         effect->direction = ml_calculate_direction(
 279                                 effect->direction,
 280                                 effect->u.rumble.weak_magnitude,
 281                                 new->direction, weak);
 282                 else
 283                         effect->direction = 0;
 284                 effect->u.rumble.strong_magnitude =
 285                         min(strong + effect->u.rumble.strong_magnitude,
 286                             0xffffU);
 287                 effect->u.rumble.weak_magnitude =
 288                         min(weak + effect->u.rumble.weak_magnitude, 0xffffU);
 289                 break;
 290
 291         case FF_PERIODIC:
 292                 i = apply_envelope(state, abs(new->u.periodic.magnitude),
 293                                    &new->u.periodic.envelope);
 294
 295                 /* here we also scale it 0x7fff => 0xffff */
 296                 i = i * gain / 0x7fff;
 297
 298                 if (effect->u.rumble.strong_magnitude + i)
 299                         effect->direction = ml_calculate_direction(
 300                                 effect->direction,
 301                                 effect->u.rumble.strong_magnitude,
 302                                 new->direction, i);
 303                 else
 304                         effect->direction = 0;
 305                 effect->u.rumble.strong_magnitude =
 306                         min(i + effect->u.rumble.strong_magnitude, 0xffffU);
 307                 effect->u.rumble.weak_magnitude =
 308                         min(i + effect->u.rumble.weak_magnitude, 0xffffU);
 309                 break;
 310
 311         default:
 312                 pr_err("invalid type in ml_combine_effects()\n");
 313                 break;
 314         }
 315
 316 }
 317
 318
 319 /*
 320  * Because memoryless devices have only one effect per effect type active
 321  * at one time we have to combine multiple effects into one
 322  */
 323 static int ml_get_combo_effect(struct ml_device *ml,
 324                                unsigned long *effect_handled,
 325                                struct ff_effect *combo_effect)
 326 {
 327         struct ff_effect *effect;
 328         struct ml_effect_state *state;
 329         int effect_type;
 330         int i;
 331
 332         memset(combo_effect, 0, sizeof(struct ff_effect));
 333
 334         for (i = 0; i < FF_MEMLESS_EFFECTS; i++) {
 335                 if (__test_and_set_bit(i, effect_handled))
 336                         continue;
 337
 338                 state = &ml->states[i];
 339                 effect = state->effect;
 340
 341                 if (!test_bit(FF_EFFECT_STARTED, &state->flags))
 342                         continue;
 343
 344                 if (time_before(jiffies, state->play_at))
 345                         continue;
 346
 347                 /*
 348                  * here we have started effects that are either
 349                  * currently playing (and may need be aborted)
 350                  * or need to start playing.
 351                  */
 352                 effect_type = get_compatible_type(ml->dev->ff, effect->type);
 353                 if (combo_effect->type != effect_type) {
 354                         if (combo_effect->type != 0) {
 355                                 __clear_bit(i, effect_handled);
 356                                 continue;
 357                         }
 358                         combo_effect->type = effect_type;
 359                 }
 360
 361                 if (__test_and_clear_bit(FF_EFFECT_ABORTING, &state->flags)) {
 362                         __clear_bit(FF_EFFECT_PLAYING, &state->flags);
 363                         __clear_bit(FF_EFFECT_STARTED, &state->flags);
 364                 } else if (effect->replay.length &&
 365                            time_after_eq(jiffies, state->stop_at)) {
 366
 367                         __clear_bit(FF_EFFECT_PLAYING, &state->flags);
 368
 369                         if (--state->count <= 0) {
 370                                 __clear_bit(FF_EFFECT_STARTED, &state->flags);
 371                         } else {
 372                                 state->play_at = jiffies +
 373                                         msecs_to_jiffies(effect->replay.delay);
 374                                 state->stop_at = state->play_at +
 375                                         msecs_to_jiffies(effect->replay.length);
 376                         }
 377                 } else {
 378                         __set_bit(FF_EFFECT_PLAYING, &state->flags);
 379                         state->adj_at = jiffies;
 380                         ml_combine_effects(combo_effect, state, ml->gain);
 381                 }
 382         }
 383
 384         return combo_effect->type != 0;
 385 }
 386
 387 static void ml_play_effects(struct ml_device *ml)
 388 {
 389         struct ff_effect effect;
 390         DECLARE_BITMAP(handled_bm, FF_MEMLESS_EFFECTS);
 391
 392         memset(handled_bm, 0, sizeof(handled_bm));
 393
 394         while (ml_get_combo_effect(ml, handled_bm, &effect))
 395                 ml->play_effect(ml->dev, ml->private, &effect);
 396
 397         ml_schedule_timer(ml);
 398 }
 399
 400 static void ml_effect_timer(struct timer_list *t)
 401 {
 402         struct ml_device *ml = from_timer(ml, t, timer);
 403         struct input_dev *dev = ml->dev;
 404         unsigned long flags;
 405
 406         pr_debug("timer: updating effects\n");
 407
 408         spin_lock_irqsave(&dev->event_lock, flags);
 409         ml_play_effects(ml);
 410         spin_unlock_irqrestore(&dev->event_lock, flags);
 411 }
 412
 413 /*
 414  * Sets requested gain for FF effects. Called with dev->event_lock held.
 415  */
 416 static void ml_ff_set_gain(struct input_dev *dev, u16 gain)
 417 {
 418         struct ml_device *ml = dev->ff->private;
 419         int i;
 420
 421         ml->gain = gain;
 422
 423         for (i = 0; i < FF_MEMLESS_EFFECTS; i++)
 424                 __clear_bit(FF_EFFECT_PLAYING, &ml->states[i].flags);
 425
 426         ml_play_effects(ml);
 427 }
 428
 429 /*
 430  * Start/stop specified FF effect. Called with dev->event_lock held.
 431  */
 432 static int ml_ff_playback(struct input_dev *dev, int effect_id, int value)
 433 {
 434         struct ml_device *ml = dev->ff->private;
 435         struct ml_effect_state *state = &ml->states[effect_id];
 436
 437         if (value > 0) {
 438                 pr_debug("initiated play\n");
 439
 440                 __set_bit(FF_EFFECT_STARTED, &state->flags);
 441                 state->count = value;
 442                 state->play_at = jiffies +
 443                                  msecs_to_jiffies(state->effect->replay.delay);
 444                 state->stop_at = state->play_at +
 445                                  msecs_to_jiffies(state->effect->replay.length);
 446                 state->adj_at = state->play_at;
 447
 448         } else {
 449                 pr_debug("initiated stop\n");
 450
 451                 if (test_bit(FF_EFFECT_PLAYING, &state->flags))
 452                         __set_bit(FF_EFFECT_ABORTING, &state->flags);
 453                 else
 454                         __clear_bit(FF_EFFECT_STARTED, &state->flags);
 455         }
 456
 457         ml_play_effects(ml);
 458
 459         return 0;
 460 }
 461
 462 static int ml_ff_upload(struct input_dev *dev,
 463                         struct ff_effect *effect, struct ff_effect *old)
 464 {
 465         struct ml_device *ml = dev->ff->private;
 466         struct ml_effect_state *state = &ml->states[effect->id];
 467
 468         spin_lock_irq(&dev->event_lock);
 469
 470         if (test_bit(FF_EFFECT_STARTED, &state->flags)) {
 471                 __clear_bit(FF_EFFECT_PLAYING, &state->flags);
 472                 state->play_at = jiffies +
 473                                  msecs_to_jiffies(state->effect->replay.delay);
 474                 state->stop_at = state->play_at +
 475                                  msecs_to_jiffies(state->effect->replay.length);
 476                 state->adj_at = state->play_at;
 477                 ml_schedule_timer(ml);
 478         }
 479
 480         spin_unlock_irq(&dev->event_lock);
 481
 482         return 0;
 483 }
 484
 485 static void ml_ff_destroy(struct ff_device *ff)
 486 {
 487         struct ml_device *ml = ff->private;
 488
 489         /*
 490          * Even though we stop all playing effects when tearing down
 491          * an input device (via input_device_flush() that calls into
 492          * input_ff_flush() that stops and erases all effects), we
 493          * do not actually stop the timer, and therefore we should
 494          * do it here.
 495          */
 496         del_timer_sync(&ml->timer);
 497
 498         kfree(ml->private);
 499 }
 500
 501 /**
 502  * input_ff_create_memless() - create memoryless force-feedback device
 503  * @dev: input device supporting force-feedback
 504  * @data: driver-specific data to be passed into @play_effect
 505  * @play_effect: driver-specific method for playing FF effect
 506  */
 507 int input_ff_create_memless(struct input_dev *dev, void *data,
 508                 int (*play_effect)(struct input_dev *, void *, struct ff_effect *))
 509 {
 510         struct ml_device *ml;
 511         struct ff_device *ff;
 512         int error;
 513         int i;
 514
 515         ml = kzalloc(sizeof(struct ml_device), GFP_KERNEL);
 516         if (!ml)
 517                 return -ENOMEM;
 518
 519         ml->dev = dev;
 520         ml->private = data;
 521         ml->play_effect = play_effect;
 522         ml->gain = 0xffff;
 523         timer_setup(&ml->timer, ml_effect_timer, 0);
 524
 525         set_bit(FF_GAIN, dev->ffbit);
 526
 527         error = input_ff_create(dev, FF_MEMLESS_EFFECTS);
 528         if (error) {
 529                 kfree(ml);
 530                 return error;
 531         }
 532
 533         ff = dev->ff;
 534         ff->private = ml;
 535         ff->upload = ml_ff_upload;
 536         ff->playback = ml_ff_playback;
 537         ff->set_gain = ml_ff_set_gain;
 538         ff->destroy = ml_ff_destroy;
 539
 540         /* we can emulate periodic effects with RUMBLE */
 541         if (test_bit(FF_RUMBLE, ff->ffbit)) {
 542                 set_bit(FF_PERIODIC, dev->ffbit);
 543                 set_bit(FF_SINE, dev->ffbit);
 544                 set_bit(FF_TRIANGLE, dev->ffbit);
 545                 set_bit(FF_SQUARE, dev->ffbit);
 546         }
 547
 548         for (i = 0; i < FF_MEMLESS_EFFECTS; i++)
 549                 ml->states[i].effect = &ff->effects[i];
 550
 551         return 0;
 552 }
 553 EXPORT_SYMBOL_GPL(input_ff_create_memless);