root/drivers/input/ff-memless.c

DEFINITIONS

1. get_envelope
2. calculate_next_time
3. ml_schedule_timer
4. apply_envelope
5. get_compatible_type
6. ml_calculate_direction
7. fixp_new16
8. fixp_mult
9. ml_combine_effects
10. ml_get_combo_effect
11. ml_play_effects
12. ml_effect_timer
13. ml_ff_set_gain
14. ml_ff_playback
15. ml_ff_upload
16. ml_ff_destroy
17. input_ff_create_memless

   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 /*
  10  */
  11 
  12 /* #define DEBUG */
  13 
  14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15 
  16 #include <linux/slab.h>
  17 #include <linux/input.h>
  18 #include <linux/module.h>
  19 #include <linux/mutex.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/jiffies.h>
  22 #include <linux/fixp-arith.h>
  23 
  24 MODULE_LICENSE("GPL");
  25 MODULE_AUTHOR("Anssi Hannula <anssi.hannula@gmail.com>");
  26 MODULE_DESCRIPTION("Force feedback support for memoryless devices");
  27 
  28 /* Number of effects handled with memoryless devices */
  29 #define FF_MEMLESS_EFFECTS      16
  30 
  31 /* Envelope update interval in ms */
  32 #define FF_ENVELOPE_INTERVAL    50
  33 
  34 #define FF_EFFECT_STARTED       0
  35 #define FF_EFFECT_PLAYING       1
  36 #define FF_EFFECT_ABORTING      2
  37 
  38 struct ml_effect_state {
  39         struct ff_effect *effect;
  40         unsigned long flags;    /* effect state (STARTED, PLAYING, etc) */
  41         int count;              /* loop count of the effect */
  42         unsigned long play_at;  /* start time */
  43         unsigned long stop_at;  /* stop time */
  44         unsigned long adj_at;   /* last time the effect was sent */
  45 };
  46 
  47 struct ml_device {
  48         void *private;
  49         struct ml_effect_state states[FF_MEMLESS_EFFECTS];
  50         int gain;
  51         struct timer_list timer;
  52         struct input_dev *dev;
  53 
  54         int (*play_effect)(struct input_dev *dev, void *data,
  55                            struct ff_effect *effect);
  56 };
  57 
  58 static const struct ff_envelope *get_envelope(const struct ff_effect *effect)
  59 {
  60         static const struct ff_envelope empty_envelope;
  61 
  62         switch (effect->type) {
  63         case FF_PERIODIC:
  64                 return &effect->u.periodic.envelope;
  65 
  66         case FF_CONSTANT:
  67                 return &effect->u.constant.envelope;
  68 
  69         default:
  70                 return &empty_envelope;
  71         }
  72 }
  73 
  74 /*
  75  * Check for the next time envelope requires an update on memoryless devices
  76  */
  77 static unsigned long calculate_next_time(struct ml_effect_state *state)
  78 {
  79         const struct ff_envelope *envelope = get_envelope(state->effect);
  80         unsigned long attack_stop, fade_start, next_fade;
  81 
  82         if (envelope->attack_length) {
  83                 attack_stop = state->play_at +
  84                         msecs_to_jiffies(envelope->attack_length);
  85                 if (time_before(state->adj_at, attack_stop))
  86                         return state->adj_at +
  87                                         msecs_to_jiffies(FF_ENVELOPE_INTERVAL);
  88         }
  89 
  90         if (state->effect->replay.length) {
  91                 if (envelope->fade_length) {
  92                         /* check when fading should start */
  93                         fade_start = state->stop_at -
  94                                         msecs_to_jiffies(envelope->fade_length);
  95 
  96                         if (time_before(state->adj_at, fade_start))
  97                                 return fade_start;
  98 
  99                         /* already fading, advance to next checkpoint */
 100                         next_fade = state->adj_at +
 101                                         msecs_to_jiffies(FF_ENVELOPE_INTERVAL);
 102                         if (time_before(next_fade, state->stop_at))
 103                                 return next_fade;
 104                 }
 105 
 106                 return state->stop_at;
 107         }
 108 
 109         return state->play_at;
 110 }
 111 
 112 static void ml_schedule_timer(struct ml_device *ml)
 113 {
 114         struct ml_effect_state *state;
 115         unsigned long now = jiffies;
 116         unsigned long earliest = 0;
 117         unsigned long next_at;
 118         int events = 0;
 119         int i;
 120 
 121         pr_debug("calculating next timer\n");
 122 
 123         for (i = 0; i < FF_MEMLESS_EFFECTS; i++) {
 124 
 125                 state = &ml->states[i];
 126 
 127                 if (!test_bit(FF_EFFECT_STARTED, &state->flags))
 128                         continue;
 129 
 130                 if (test_bit(FF_EFFECT_PLAYING, &state->flags))
 131                         next_at = calculate_next_time(state);
 132                 else
 133                         next_at = state->play_at;
 134 
 135                 if (time_before_eq(now, next_at) &&
 136                     (++events == 1 || time_before(next_at, earliest)))
 137                         earliest = next_at;
 138         }
 139 
 140         if (!events) {
 141                 pr_debug("no actions\n");
 142                 del_timer(&ml->timer);
 143         } else {
 144                 pr_debug("timer set\n");
 145                 mod_timer(&ml->timer, earliest);
 146         }
 147 }
 148 
 149 /*
 150  * Apply an envelope to a value
 151  */
 152 static int apply_envelope(struct ml_effect_state *state, int value,
 153                           struct ff_envelope *envelope)
 154 {
 155         struct ff_effect *effect = state->effect;
 156         unsigned long now = jiffies;
 157         int time_from_level;
 158         int time_of_envelope;
 159         int envelope_level;
 160         int difference;
 161 
 162         if (envelope->attack_length &&
 163             time_before(now,
 164                         state->play_at + msecs_to_jiffies(envelope->attack_length))) {
 165                 pr_debug("value = 0x%x, attack_level = 0x%x\n",
 166                          value, envelope->attack_level);
 167                 time_from_level = jiffies_to_msecs(now - state->play_at);
 168                 time_of_envelope = envelope->attack_length;
 169                 envelope_level = min_t(u16, envelope->attack_level, 0x7fff);
 170 
 171         } else if (envelope->fade_length && effect->replay.length &&
 172                    time_after(now,
 173                               state->stop_at - msecs_to_jiffies(envelope->fade_length)) &&
 174                    time_before(now, state->stop_at)) {
 175                 time_from_level = jiffies_to_msecs(state->stop_at - now);
 176                 time_of_envelope = envelope->fade_length;
 177                 envelope_level = min_t(u16, envelope->fade_level, 0x7fff);
 178         } else
 179                 return value;
 180 
 181         difference = abs(value) - envelope_level;
 182 
 183         pr_debug("difference = %d\n", difference);
 184         pr_debug("time_from_level = 0x%x\n", time_from_level);
 185         pr_debug("time_of_envelope = 0x%x\n", time_of_envelope);
 186 
 187         difference = difference * time_from_level / time_of_envelope;
 188 
 189         pr_debug("difference = %d\n", difference);
 190 
 191         return value < 0 ?
 192                 -(difference + envelope_level) : (difference + envelope_level);
 193 }
 194 
 195 /*
 196  * Return the type the effect has to be converted into (memless devices)
 197  */
 198 static int get_compatible_type(struct ff_device *ff, int effect_type)
 199 {
 200 
 201         if (test_bit(effect_type, ff->ffbit))
 202                 return effect_type;
 203 
 204         if (effect_type == FF_PERIODIC && test_bit(FF_RUMBLE, ff->ffbit))
 205                 return FF_RUMBLE;
 206 
 207         pr_err("invalid type in get_compatible_type()\n");
 208 
 209         return 0;
 210 }
 211 
 212 /*
 213  * Only left/right direction should be used (under/over 0x8000) for
 214  * forward/reverse motor direction (to keep calculation fast & simple).
 215  */
 216 static u16 ml_calculate_direction(u16 direction, u16 force,
 217                                   u16 new_direction, u16 new_force)
 218 {
 219         if (!force)
 220                 return new_direction;
 221         if (!new_force)
 222                 return direction;
 223         return (((u32)(direction >> 1) * force +
 224                  (new_direction >> 1) * new_force) /
 225                 (force + new_force)) << 1;
 226 }
 227 
 228 #define FRAC_N 8
 229 static inline s16 fixp_new16(s16 a)
 230 {
 231         return ((s32)a) >> (16 - FRAC_N);
 232 }
 233 
 234 static inline s16 fixp_mult(s16 a, s16 b)
 235 {
 236         a = ((s32)a * 0x100) / 0x7fff;
 237         return ((s32)(a * b)) >> FRAC_N;
 238 }
 239 
 240 /*
 241  * Combine two effects and apply gain.
 242  */
 243 static 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         s16 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_sin16(i), level) * gain / 0xffff;
 259                 y = fixp_mult(-fixp_cos16(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  */
 326 static 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 
 390 static 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 
 403 static void ml_effect_timer(struct timer_list *t)
 404 {
 405         struct ml_device *ml = from_timer(ml, t, timer);
 406         struct input_dev *dev = ml->dev;
 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  */
 419 static 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  */
 435 static 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 
 465 static 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 
 488 static void ml_ff_destroy(struct ff_device *ff)
 489 {
 490         struct ml_device *ml = ff->private;
 491 
 492         /*
 493          * Even though we stop all playing effects when tearing down
 494          * an input device (via input_device_flush() that calls into
 495          * input_ff_flush() that stops and erases all effects), we
 496          * do not actually stop the timer, and therefore we should
 497          * do it here.
 498          */
 499         del_timer_sync(&ml->timer);
 500 
 501         kfree(ml->private);
 502 }
 503 
 504 /**
 505  * input_ff_create_memless() - create memoryless force-feedback device
 506  * @dev: input device supporting force-feedback
 507  * @data: driver-specific data to be passed into @play_effect
 508  * @play_effect: driver-specific method for playing FF effect
 509  */
 510 int input_ff_create_memless(struct input_dev *dev, void *data,
 511                 int (*play_effect)(struct input_dev *, void *, struct ff_effect *))
 512 {
 513         struct ml_device *ml;
 514         struct ff_device *ff;
 515         int error;
 516         int i;
 517 
 518         ml = kzalloc(sizeof(struct ml_device), GFP_KERNEL);
 519         if (!ml)
 520                 return -ENOMEM;
 521 
 522         ml->dev = dev;
 523         ml->private = data;
 524         ml->play_effect = play_effect;
 525         ml->gain = 0xffff;
 526         timer_setup(&ml->timer, ml_effect_timer, 0);
 527 
 528         set_bit(FF_GAIN, dev->ffbit);
 529 
 530         error = input_ff_create(dev, FF_MEMLESS_EFFECTS);
 531         if (error) {
 532                 kfree(ml);
 533                 return error;
 534         }
 535 
 536         ff = dev->ff;
 537         ff->private = ml;
 538         ff->upload = ml_ff_upload;
 539         ff->playback = ml_ff_playback;
 540         ff->set_gain = ml_ff_set_gain;
 541         ff->destroy = ml_ff_destroy;
 542 
 543         /* we can emulate periodic effects with RUMBLE */
 544         if (test_bit(FF_RUMBLE, ff->ffbit)) {
 545                 set_bit(FF_PERIODIC, dev->ffbit);
 546                 set_bit(FF_SINE, dev->ffbit);
 547                 set_bit(FF_TRIANGLE, dev->ffbit);
 548                 set_bit(FF_SQUARE, dev->ffbit);
 549         }
 550 
 551         for (i = 0; i < FF_MEMLESS_EFFECTS; i++)
 552                 ml->states[i].effect = &ff->effects[i];
 553 
 554         return 0;
 555 }
 556 EXPORT_SYMBOL_GPL(input_ff_create_memless);