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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Force feedback support for memoryless devices
4 *
5 * Copyright (c) 2006 Anssi Hannula <[email protected]>
6 * Copyright (c) 2006 Dmitry Torokhov <[email protected]>
7 */
8
9/* #define DEBUG */
10
11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13#include <linux/export.h>
14#include <linux/slab.h>
15#include <linux/input.h>
16#include <linux/module.h>
17#include <linux/mutex.h>
18#include <linux/spinlock.h>
19#include <linux/jiffies.h>
20#include <linux/fixp-arith.h>
21
22MODULE_LICENSE("GPL");
23MODULE_AUTHOR("Anssi Hannula <[email protected]>");
24MODULE_DESCRIPTION("Force feedback support for memoryless devices");
25
26/* Number of effects handled with memoryless devices */
27#define FF_MEMLESS_EFFECTS 16
28
29/* Envelope update interval in ms */
30#define FF_ENVELOPE_INTERVAL 50
31
32#define FF_EFFECT_STARTED 0
33#define FF_EFFECT_PLAYING 1
34#define FF_EFFECT_ABORTING 2
35
36struct ml_effect_state {
37 struct ff_effect *effect;
38 unsigned long flags; /* effect state (STARTED, PLAYING, etc) */
39 int count; /* loop count of the effect */
40 unsigned long play_at; /* start time */
41 unsigned long stop_at; /* stop time */
42 unsigned long adj_at; /* last time the effect was sent */
43};
44
45struct ml_device {
46 void *private;
47 struct ml_effect_state states[FF_MEMLESS_EFFECTS];
48 int gain;
49 struct timer_list timer;
50 struct input_dev *dev;
51
52 int (*play_effect)(struct input_dev *dev, void *data,
53 struct ff_effect *effect);
54};
55
56static const struct ff_envelope *get_envelope(const struct ff_effect *effect)
57{
58 static const struct ff_envelope empty_envelope;
59
60 switch (effect->type) {
61 case FF_PERIODIC:
62 return &effect->u.periodic.envelope;
63
64 case FF_CONSTANT:
65 return &effect->u.constant.envelope;
66
67 default:
68 return &empty_envelope;
69 }
70}
71
72/*
73 * Check for the next time envelope requires an update on memoryless devices
74 */
75static unsigned long calculate_next_time(struct ml_effect_state *state)
76{
77 const struct ff_envelope *envelope = get_envelope(state->effect);
78 unsigned long attack_stop, fade_start, next_fade;
79
80 if (envelope->attack_length) {
81 attack_stop = state->play_at +
82 msecs_to_jiffies(envelope->attack_length);
83 if (time_before(state->adj_at, attack_stop))
84 return state->adj_at +
85 msecs_to_jiffies(FF_ENVELOPE_INTERVAL);
86 }
87
88 if (state->effect->replay.length) {
89 if (envelope->fade_length) {
90 /* check when fading should start */
91 fade_start = state->stop_at -
92 msecs_to_jiffies(envelope->fade_length);
93
94 if (time_before(state->adj_at, fade_start))
95 return fade_start;
96
97 /* already fading, advance to next checkpoint */
98 next_fade = state->adj_at +
99 msecs_to_jiffies(FF_ENVELOPE_INTERVAL);
100 if (time_before(next_fade, state->stop_at))
101 return next_fade;
102 }
103
104 return state->stop_at;
105 }
106
107 return state->play_at;
108}
109
110static void ml_schedule_timer(struct ml_device *ml)
111{
112 struct ml_effect_state *state;
113 unsigned long now = jiffies;
114 unsigned long earliest = 0;
115 unsigned long next_at;
116 int events = 0;
117 int i;
118
119 pr_debug("calculating next timer\n");
120
121 for (i = 0; i < FF_MEMLESS_EFFECTS; i++) {
122
123 state = &ml->states[i];
124
125 if (!test_bit(FF_EFFECT_STARTED, &state->flags))
126 continue;
127
128 if (test_bit(FF_EFFECT_PLAYING, &state->flags))
129 next_at = calculate_next_time(state);
130 else
131 next_at = state->play_at;
132
133 if (time_before_eq(now, next_at) &&
134 (++events == 1 || time_before(next_at, earliest)))
135 earliest = next_at;
136 }
137
138 if (!events) {
139 pr_debug("no actions\n");
140 timer_delete(&ml->timer);
141 } else {
142 pr_debug("timer set\n");
143 mod_timer(&ml->timer, earliest);
144 }
145}
146
147/*
148 * Apply an envelope to a value
149 */
150static int apply_envelope(struct ml_effect_state *state, int value,
151 struct ff_envelope *envelope)
152{
153 struct ff_effect *effect = state->effect;
154 unsigned long now = jiffies;
155 int time_from_level;
156 int time_of_envelope;
157 int envelope_level;
158 int difference;
159
160 if (envelope->attack_length &&
161 time_before(now,
162 state->play_at + msecs_to_jiffies(envelope->attack_length))) {
163 pr_debug("value = 0x%x, attack_level = 0x%x\n",
164 value, envelope->attack_level);
165 time_from_level = jiffies_to_msecs(now - state->play_at);
166 time_of_envelope = envelope->attack_length;
167 envelope_level = min_t(u16, envelope->attack_level, 0x7fff);
168
169 } else if (envelope->fade_length && effect->replay.length &&
170 time_after(now,
171 state->stop_at - msecs_to_jiffies(envelope->fade_length)) &&
172 time_before(now, state->stop_at)) {
173 time_from_level = jiffies_to_msecs(state->stop_at - now);
174 time_of_envelope = envelope->fade_length;
175 envelope_level = min_t(u16, envelope->fade_level, 0x7fff);
176 } else
177 return value;
178
179 difference = abs(value) - envelope_level;
180
181 pr_debug("difference = %d\n", difference);
182 pr_debug("time_from_level = 0x%x\n", time_from_level);
183 pr_debug("time_of_envelope = 0x%x\n", time_of_envelope);
184
185 difference = difference * time_from_level / time_of_envelope;
186
187 pr_debug("difference = %d\n", difference);
188
189 return value < 0 ?
190 -(difference + envelope_level) : (difference + envelope_level);
191}
192
193/*
194 * Return the type the effect has to be converted into (memless devices)
195 */
196static int get_compatible_type(struct ff_device *ff, int effect_type)
197{
198
199 if (test_bit(effect_type, ff->ffbit))
200 return effect_type;
201
202 if (effect_type == FF_PERIODIC && test_bit(FF_RUMBLE, ff->ffbit))
203 return FF_RUMBLE;
204
205 pr_err("invalid type in get_compatible_type()\n");
206
207 return 0;
208}
209
210/*
211 * Only left/right direction should be used (under/over 0x8000) for
212 * forward/reverse motor direction (to keep calculation fast & simple).
213 */
214static u16 ml_calculate_direction(u16 direction, u16 force,
215 u16 new_direction, u16 new_force)
216{
217 if (!force)
218 return new_direction;
219 if (!new_force)
220 return direction;
221 return (((u32)(direction >> 1) * force +
222 (new_direction >> 1) * new_force) /
223 (force + new_force)) << 1;
224}
225
226#define FRAC_N 8
227static inline s16 fixp_new16(s16 a)
228{
229 return ((s32)a) >> (16 - FRAC_N);
230}
231
232static inline s16 fixp_mult(s16 a, s16 b)
233{
234 a = ((s32)a * 0x100) / 0x7fff;
235 return ((s32)(a * b)) >> FRAC_N;
236}
237
238/*
239 * Combine two effects and apply gain.
240 */
241static void ml_combine_effects(struct ff_effect *effect,
242 struct ml_effect_state *state,
243 int gain)
244{
245 struct ff_effect *new = state->effect;
246 unsigned int strong, weak, i;
247 int x, y;
248 s16 level;
249
250 switch (new->type) {
251 case FF_CONSTANT:
252 i = new->direction * 360 / 0xffff;
253 level = fixp_new16(apply_envelope(state,
254 new->u.constant.level,
255 &new->u.constant.envelope));
256 x = fixp_mult(fixp_sin16(i), level) * gain / 0xffff;
257 y = fixp_mult(-fixp_cos16(i), level) * gain / 0xffff;
258 /*
259 * here we abuse ff_ramp to hold x and y of constant force
260 * If in future any driver wants something else than x and y
261 * in s8, this should be changed to something more generic
262 */
263 effect->u.ramp.start_level =
264 clamp_val(effect->u.ramp.start_level + x, -0x80, 0x7f);
265 effect->u.ramp.end_level =
266 clamp_val(effect->u.ramp.end_level + y, -0x80, 0x7f);
267 break;
268
269 case FF_RUMBLE:
270 strong = (u32)new->u.rumble.strong_magnitude * gain / 0xffff;
271 weak = (u32)new->u.rumble.weak_magnitude * gain / 0xffff;
272
273 if (effect->u.rumble.strong_magnitude + strong)
274 effect->direction = ml_calculate_direction(
275 effect->direction,
276 effect->u.rumble.strong_magnitude,
277 new->direction, strong);
278 else if (effect->u.rumble.weak_magnitude + weak)
279 effect->direction = ml_calculate_direction(
280 effect->direction,
281 effect->u.rumble.weak_magnitude,
282 new->direction, weak);
283 else
284 effect->direction = 0;
285 effect->u.rumble.strong_magnitude =
286 min(strong + effect->u.rumble.strong_magnitude,
287 0xffffU);
288 effect->u.rumble.weak_magnitude =
289 min(weak + effect->u.rumble.weak_magnitude, 0xffffU);
290 break;
291
292 case FF_PERIODIC:
293 i = apply_envelope(state, abs(new->u.periodic.magnitude),
294 &new->u.periodic.envelope);
295
296 /* here we also scale it 0x7fff => 0xffff */
297 i = i * gain / 0x7fff;
298
299 if (effect->u.rumble.strong_magnitude + i)
300 effect->direction = ml_calculate_direction(
301 effect->direction,
302 effect->u.rumble.strong_magnitude,
303 new->direction, i);
304 else
305 effect->direction = 0;
306 effect->u.rumble.strong_magnitude =
307 min(i + effect->u.rumble.strong_magnitude, 0xffffU);
308 effect->u.rumble.weak_magnitude =
309 min(i + effect->u.rumble.weak_magnitude, 0xffffU);
310 break;
311
312 default:
313 pr_err("invalid type in ml_combine_effects()\n");
314 break;
315 }
316
317}
318
319
320/*
321 * Because memoryless devices have only one effect per effect type active
322 * at one time we have to combine multiple effects into one
323 */
324static int ml_get_combo_effect(struct ml_device *ml,
325 unsigned long *effect_handled,
326 struct ff_effect *combo_effect)
327{
328 struct ff_effect *effect;
329 struct ml_effect_state *state;
330 int effect_type;
331 int i;
332
333 memset(combo_effect, 0, sizeof(struct ff_effect));
334
335 for (i = 0; i < FF_MEMLESS_EFFECTS; i++) {
336 if (__test_and_set_bit(i, effect_handled))
337 continue;
338
339 state = &ml->states[i];
340 effect = state->effect;
341
342 if (!test_bit(FF_EFFECT_STARTED, &state->flags))
343 continue;
344
345 if (time_before(jiffies, state->play_at))
346 continue;
347
348 /*
349 * here we have started effects that are either
350 * currently playing (and may need be aborted)
351 * or need to start playing.
352 */
353 effect_type = get_compatible_type(ml->dev->ff, effect->type);
354 if (combo_effect->type != effect_type) {
355 if (combo_effect->type != 0) {
356 __clear_bit(i, effect_handled);
357 continue;
358 }
359 combo_effect->type = effect_type;
360 }
361
362 if (__test_and_clear_bit(FF_EFFECT_ABORTING, &state->flags)) {
363 __clear_bit(FF_EFFECT_PLAYING, &state->flags);
364 __clear_bit(FF_EFFECT_STARTED, &state->flags);
365 } else if (effect->replay.length &&
366 time_after_eq(jiffies, state->stop_at)) {
367
368 __clear_bit(FF_EFFECT_PLAYING, &state->flags);
369
370 if (--state->count <= 0) {
371 __clear_bit(FF_EFFECT_STARTED, &state->flags);
372 } else {
373 state->play_at = jiffies +
374 msecs_to_jiffies(effect->replay.delay);
375 state->stop_at = state->play_at +
376 msecs_to_jiffies(effect->replay.length);
377 }
378 } else {
379 __set_bit(FF_EFFECT_PLAYING, &state->flags);
380 state->adj_at = jiffies;
381 ml_combine_effects(combo_effect, state, ml->gain);
382 }
383 }
384
385 return combo_effect->type != 0;
386}
387
388static void ml_play_effects(struct ml_device *ml)
389{
390 struct ff_effect effect;
391 DECLARE_BITMAP(handled_bm, FF_MEMLESS_EFFECTS);
392
393 memset(handled_bm, 0, sizeof(handled_bm));
394
395 while (ml_get_combo_effect(ml, handled_bm, &effect))
396 ml->play_effect(ml->dev, ml->private, &effect);
397
398 ml_schedule_timer(ml);
399}
400
401static void ml_effect_timer(struct timer_list *t)
402{
403 struct ml_device *ml = timer_container_of(ml, t, timer);
404 struct input_dev *dev = ml->dev;
405
406 pr_debug("timer: updating effects\n");
407
408 guard(spinlock_irqsave)(&dev->event_lock);
409 ml_play_effects(ml);
410}
411
412/*
413 * Sets requested gain for FF effects. Called with dev->event_lock held.
414 */
415static void ml_ff_set_gain(struct input_dev *dev, u16 gain)
416{
417 struct ml_device *ml = dev->ff->private;
418 int i;
419
420 ml->gain = gain;
421
422 for (i = 0; i < FF_MEMLESS_EFFECTS; i++)
423 __clear_bit(FF_EFFECT_PLAYING, &ml->states[i].flags);
424
425 ml_play_effects(ml);
426}
427
428/*
429 * Start/stop specified FF effect. Called with dev->event_lock held.
430 */
431static int ml_ff_playback(struct input_dev *dev, int effect_id, int value)
432{
433 struct ml_device *ml = dev->ff->private;
434 struct ml_effect_state *state = &ml->states[effect_id];
435
436 if (value > 0) {
437 pr_debug("initiated play\n");
438
439 __set_bit(FF_EFFECT_STARTED, &state->flags);
440 state->count = value;
441 state->play_at = jiffies +
442 msecs_to_jiffies(state->effect->replay.delay);
443 state->stop_at = state->play_at +
444 msecs_to_jiffies(state->effect->replay.length);
445 state->adj_at = state->play_at;
446
447 } else {
448 pr_debug("initiated stop\n");
449
450 if (test_bit(FF_EFFECT_PLAYING, &state->flags))
451 __set_bit(FF_EFFECT_ABORTING, &state->flags);
452 else
453 __clear_bit(FF_EFFECT_STARTED, &state->flags);
454 }
455
456 ml_play_effects(ml);
457
458 return 0;
459}
460
461static int ml_ff_upload(struct input_dev *dev,
462 struct ff_effect *effect, struct ff_effect *old)
463{
464 struct ml_device *ml = dev->ff->private;
465 struct ml_effect_state *state = &ml->states[effect->id];
466
467 guard(spinlock_irq)(&dev->event_lock);
468
469 if (test_bit(FF_EFFECT_STARTED, &state->flags)) {
470 __clear_bit(FF_EFFECT_PLAYING, &state->flags);
471 state->play_at = jiffies +
472 msecs_to_jiffies(state->effect->replay.delay);
473 state->stop_at = state->play_at +
474 msecs_to_jiffies(state->effect->replay.length);
475 state->adj_at = state->play_at;
476 ml_schedule_timer(ml);
477 }
478
479 return 0;
480}
481
482static void ml_ff_destroy(struct ff_device *ff)
483{
484 struct ml_device *ml = ff->private;
485
486 /*
487 * The timer is normally shut down in ml_ff_stop() when the device
488 * is unregistered. However, we still shut it down here as a safety
489 * net and for cases where the device was never registered (e.g.
490 * error paths during probe).
491 */
492 timer_shutdown_sync(&ml->timer);
493
494 kfree(ml->private);
495}
496
497static void ml_ff_stop(struct ff_device *ff)
498{
499 struct ml_device *ml = ff->private;
500
501 /*
502 * Even though we stop all playing effects when tearing down an
503 * input device (by the way of evdev calling input_flush_device()
504 * that calls into input_ff_flush() that stops and erases all
505 * effects), we do not actually shutdown the timer, and therefore
506 * we should do it here to prevent it firing after the input
507 * device is unregistered and its associated resources are freed.
508 */
509 timer_shutdown_sync(&ml->timer);
510}
511
512/**
513 * input_ff_create_memless() - create memoryless force-feedback device
514 * @dev: input device supporting force-feedback
515 * @data: driver-specific data to be passed into @play_effect
516 * @play_effect: driver-specific method for playing FF effect
517 */
518int input_ff_create_memless(struct input_dev *dev, void *data,
519 int (*play_effect)(struct input_dev *, void *, struct ff_effect *))
520{
521 struct ff_device *ff;
522 int error;
523 int i;
524
525 struct ml_device *ml __free(kfree) = kzalloc_obj(*ml);
526 if (!ml)
527 return -ENOMEM;
528
529 ml->dev = dev;
530 ml->private = data;
531 ml->play_effect = play_effect;
532 ml->gain = 0xffff;
533 timer_setup(&ml->timer, ml_effect_timer, 0);
534
535 set_bit(FF_GAIN, dev->ffbit);
536
537 error = input_ff_create(dev, FF_MEMLESS_EFFECTS);
538 if (error)
539 return error;
540
541 ff = dev->ff;
542 ff->upload = ml_ff_upload;
543 ff->playback = ml_ff_playback;
544 ff->set_gain = ml_ff_set_gain;
545 ff->destroy = ml_ff_destroy;
546 ff->stop = ml_ff_stop;
547
548 /* we can emulate periodic effects with RUMBLE */
549 if (test_bit(FF_RUMBLE, ff->ffbit)) {
550 set_bit(FF_PERIODIC, dev->ffbit);
551 set_bit(FF_SINE, dev->ffbit);
552 set_bit(FF_TRIANGLE, dev->ffbit);
553 set_bit(FF_SQUARE, dev->ffbit);
554 }
555
556 for (i = 0; i < FF_MEMLESS_EFFECTS; i++)
557 ml->states[i].effect = &ff->effects[i];
558
559 ff->private = no_free_ptr(ml);
560
561 return 0;
562}
563EXPORT_SYMBOL_GPL(input_ff_create_memless);