drivers/input/ff-memless.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *  Force feedback support for memoryless devices
0004  *
0005  *  Copyright (c) 2006 Anssi Hannula <anssi.hannula@gmail.com>
0006  *  Copyright (c) 2006 Dmitry Torokhov <dtor@mail.ru>
0007  */
0008
0009 /*
0010  */
0011
0012 /* #define DEBUG */
0013
0014 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0015
0016 #include <linux/slab.h>
0017 #include <linux/input.h>
0018 #include <linux/module.h>
0019 #include <linux/mutex.h>
0020 #include <linux/spinlock.h>
0021 #include <linux/jiffies.h>
0022 #include <linux/fixp-arith.h>
0023
0024 MODULE_LICENSE("GPL");
0025 MODULE_AUTHOR("Anssi Hannula <anssi.hannula@gmail.com>");
0026 MODULE_DESCRIPTION("Force feedback support for memoryless devices");
0027
0028 /* Number of effects handled with memoryless devices */
0029 #define FF_MEMLESS_EFFECTS  16
0030
0031 /* Envelope update interval in ms */
0032 #define FF_ENVELOPE_INTERVAL    50
0033
0034 #define FF_EFFECT_STARTED   0
0035 #define FF_EFFECT_PLAYING   1
0036 #define FF_EFFECT_ABORTING  2
0037
0038 struct ml_effect_state {
0039     struct ff_effect *effect;
0040     unsigned long flags;    /* effect state (STARTED, PLAYING, etc) */
0041     int count;      /* loop count of the effect */
0042     unsigned long play_at;  /* start time */
0043     unsigned long stop_at;  /* stop time */
0044     unsigned long adj_at;   /* last time the effect was sent */
0045 };
0046
0047 struct ml_device {
0048     void *private;
0049     struct ml_effect_state states[FF_MEMLESS_EFFECTS];
0050     int gain;
0051     struct timer_list timer;
0052     struct input_dev *dev;
0053
0054     int (*play_effect)(struct input_dev *dev, void *data,
0055                struct ff_effect *effect);
0056 };
0057
0058 static const struct ff_envelope *get_envelope(const struct ff_effect *effect)
0059 {
0060     static const struct ff_envelope empty_envelope;
0061
0062     switch (effect->type) {
0063     case FF_PERIODIC:
0064         return &effect->u.periodic.envelope;
0065
0066     case FF_CONSTANT:
0067         return &effect->u.constant.envelope;
0068
0069     default:
0070         return &empty_envelope;
0071     }
0072 }
0073
0074 /*
0075  * Check for the next time envelope requires an update on memoryless devices
0076  */
0077 static unsigned long calculate_next_time(struct ml_effect_state *state)
0078 {
0079     const struct ff_envelope *envelope = get_envelope(state->effect);
0080     unsigned long attack_stop, fade_start, next_fade;
0081
0082     if (envelope->attack_length) {
0083         attack_stop = state->play_at +
0084             msecs_to_jiffies(envelope->attack_length);
0085         if (time_before(state->adj_at, attack_stop))
0086             return state->adj_at +
0087                     msecs_to_jiffies(FF_ENVELOPE_INTERVAL);
0088     }
0089
0090     if (state->effect->replay.length) {
0091         if (envelope->fade_length) {
0092             /* check when fading should start */
0093             fade_start = state->stop_at -
0094                     msecs_to_jiffies(envelope->fade_length);
0095
0096             if (time_before(state->adj_at, fade_start))
0097                 return fade_start;
0098
0099             /* already fading, advance to next checkpoint */
0100             next_fade = state->adj_at +
0101                     msecs_to_jiffies(FF_ENVELOPE_INTERVAL);
0102             if (time_before(next_fade, state->stop_at))
0103                 return next_fade;
0104         }
0105
0106         return state->stop_at;
0107     }
0108
0109     return state->play_at;
0110 }
0111
0112 static void ml_schedule_timer(struct ml_device *ml)
0113 {
0114     struct ml_effect_state *state;
0115     unsigned long now = jiffies;
0116     unsigned long earliest = 0;
0117     unsigned long next_at;
0118     int events = 0;
0119     int i;
0120
0121     pr_debug("calculating next timer\n");
0122
0123     for (i = 0; i < FF_MEMLESS_EFFECTS; i++) {
0124
0125         state = &ml->states[i];
0126
0127         if (!test_bit(FF_EFFECT_STARTED, &state->flags))
0128             continue;
0129
0130         if (test_bit(FF_EFFECT_PLAYING, &state->flags))
0131             next_at = calculate_next_time(state);
0132         else
0133             next_at = state->play_at;
0134
0135         if (time_before_eq(now, next_at) &&
0136             (++events == 1 || time_before(next_at, earliest)))
0137             earliest = next_at;
0138     }
0139
0140     if (!events) {
0141         pr_debug("no actions\n");
0142         del_timer(&ml->timer);
0143     } else {
0144         pr_debug("timer set\n");
0145         mod_timer(&ml->timer, earliest);
0146     }
0147 }
0148
0149 /*
0150  * Apply an envelope to a value
0151  */
0152 static int apply_envelope(struct ml_effect_state *state, int value,
0153               struct ff_envelope *envelope)
0154 {
0155     struct ff_effect *effect = state->effect;
0156     unsigned long now = jiffies;
0157     int time_from_level;
0158     int time_of_envelope;
0159     int envelope_level;
0160     int difference;
0161
0162     if (envelope->attack_length &&
0163         time_before(now,
0164             state->play_at + msecs_to_jiffies(envelope->attack_length))) {
0165         pr_debug("value = 0x%x, attack_level = 0x%x\n",
0166              value, envelope->attack_level);
0167         time_from_level = jiffies_to_msecs(now - state->play_at);
0168         time_of_envelope = envelope->attack_length;
0169         envelope_level = min_t(u16, envelope->attack_level, 0x7fff);
0170
0171     } else if (envelope->fade_length && effect->replay.length &&
0172            time_after(now,
0173                   state->stop_at - msecs_to_jiffies(envelope->fade_length)) &&
0174            time_before(now, state->stop_at)) {
0175         time_from_level = jiffies_to_msecs(state->stop_at - now);
0176         time_of_envelope = envelope->fade_length;
0177         envelope_level = min_t(u16, envelope->fade_level, 0x7fff);
0178     } else
0179         return value;
0180
0181     difference = abs(value) - envelope_level;
0182
0183     pr_debug("difference = %d\n", difference);
0184     pr_debug("time_from_level = 0x%x\n", time_from_level);
0185     pr_debug("time_of_envelope = 0x%x\n", time_of_envelope);
0186
0187     difference = difference * time_from_level / time_of_envelope;
0188
0189     pr_debug("difference = %d\n", difference);
0190
0191     return value < 0 ?
0192         -(difference + envelope_level) : (difference + envelope_level);
0193 }
0194
0195 /*
0196  * Return the type the effect has to be converted into (memless devices)
0197  */
0198 static int get_compatible_type(struct ff_device *ff, int effect_type)
0199 {
0200
0201     if (test_bit(effect_type, ff->ffbit))
0202         return effect_type;
0203
0204     if (effect_type == FF_PERIODIC && test_bit(FF_RUMBLE, ff->ffbit))
0205         return FF_RUMBLE;
0206
0207     pr_err("invalid type in get_compatible_type()\n");
0208
0209     return 0;
0210 }
0211
0212 /*
0213  * Only left/right direction should be used (under/over 0x8000) for
0214  * forward/reverse motor direction (to keep calculation fast & simple).
0215  */
0216 static u16 ml_calculate_direction(u16 direction, u16 force,
0217                   u16 new_direction, u16 new_force)
0218 {
0219     if (!force)
0220         return new_direction;
0221     if (!new_force)
0222         return direction;
0223     return (((u32)(direction >> 1) * force +
0224          (new_direction >> 1) * new_force) /
0225         (force + new_force)) << 1;
0226 }
0227
0228 #define FRAC_N 8
0229 static inline s16 fixp_new16(s16 a)
0230 {
0231     return ((s32)a) >> (16 - FRAC_N);
0232 }
0233
0234 static inline s16 fixp_mult(s16 a, s16 b)
0235 {
0236     a = ((s32)a * 0x100) / 0x7fff;
0237     return ((s32)(a * b)) >> FRAC_N;
0238 }
0239
0240 /*
0241  * Combine two effects and apply gain.
0242  */
0243 static void ml_combine_effects(struct ff_effect *effect,
0244                    struct ml_effect_state *state,
0245                    int gain)
0246 {
0247     struct ff_effect *new = state->effect;
0248     unsigned int strong, weak, i;
0249     int x, y;
0250     s16 level;
0251
0252     switch (new->type) {
0253     case FF_CONSTANT:
0254         i = new->direction * 360 / 0xffff;
0255         level = fixp_new16(apply_envelope(state,
0256                     new->u.constant.level,
0257                     &new->u.constant.envelope));
0258         x = fixp_mult(fixp_sin16(i), level) * gain / 0xffff;
0259         y = fixp_mult(-fixp_cos16(i), level) * gain / 0xffff;
0260         /*
0261          * here we abuse ff_ramp to hold x and y of constant force
0262          * If in future any driver wants something else than x and y
0263          * in s8, this should be changed to something more generic
0264          */
0265         effect->u.ramp.start_level =
0266             clamp_val(effect->u.ramp.start_level + x, -0x80, 0x7f);
0267         effect->u.ramp.end_level =
0268             clamp_val(effect->u.ramp.end_level + y, -0x80, 0x7f);
0269         break;
0270
0271     case FF_RUMBLE:
0272         strong = (u32)new->u.rumble.strong_magnitude * gain / 0xffff;
0273         weak = (u32)new->u.rumble.weak_magnitude * gain / 0xffff;
0274
0275         if (effect->u.rumble.strong_magnitude + strong)
0276             effect->direction = ml_calculate_direction(
0277                 effect->direction,
0278                 effect->u.rumble.strong_magnitude,
0279                 new->direction, strong);
0280         else if (effect->u.rumble.weak_magnitude + weak)
0281             effect->direction = ml_calculate_direction(
0282                 effect->direction,
0283                 effect->u.rumble.weak_magnitude,
0284                 new->direction, weak);
0285         else
0286             effect->direction = 0;
0287         effect->u.rumble.strong_magnitude =
0288             min(strong + effect->u.rumble.strong_magnitude,
0289                 0xffffU);
0290         effect->u.rumble.weak_magnitude =
0291             min(weak + effect->u.rumble.weak_magnitude, 0xffffU);
0292         break;
0293
0294     case FF_PERIODIC:
0295         i = apply_envelope(state, abs(new->u.periodic.magnitude),
0296                    &new->u.periodic.envelope);
0297
0298         /* here we also scale it 0x7fff => 0xffff */
0299         i = i * gain / 0x7fff;
0300
0301         if (effect->u.rumble.strong_magnitude + i)
0302             effect->direction = ml_calculate_direction(
0303                 effect->direction,
0304                 effect->u.rumble.strong_magnitude,
0305                 new->direction, i);
0306         else
0307             effect->direction = 0;
0308         effect->u.rumble.strong_magnitude =
0309             min(i + effect->u.rumble.strong_magnitude, 0xffffU);
0310         effect->u.rumble.weak_magnitude =
0311             min(i + effect->u.rumble.weak_magnitude, 0xffffU);
0312         break;
0313
0314     default:
0315         pr_err("invalid type in ml_combine_effects()\n");
0316         break;
0317     }
0318
0319 }
0320
0321
0322 /*
0323  * Because memoryless devices have only one effect per effect type active
0324  * at one time we have to combine multiple effects into one
0325  */
0326 static int ml_get_combo_effect(struct ml_device *ml,
0327                    unsigned long *effect_handled,
0328                    struct ff_effect *combo_effect)
0329 {
0330     struct ff_effect *effect;
0331     struct ml_effect_state *state;
0332     int effect_type;
0333     int i;
0334
0335     memset(combo_effect, 0, sizeof(struct ff_effect));
0336
0337     for (i = 0; i < FF_MEMLESS_EFFECTS; i++) {
0338         if (__test_and_set_bit(i, effect_handled))
0339             continue;
0340
0341         state = &ml->states[i];
0342         effect = state->effect;
0343
0344         if (!test_bit(FF_EFFECT_STARTED, &state->flags))
0345             continue;
0346
0347         if (time_before(jiffies, state->play_at))
0348             continue;
0349
0350         /*
0351          * here we have started effects that are either
0352          * currently playing (and may need be aborted)
0353          * or need to start playing.
0354          */
0355         effect_type = get_compatible_type(ml->dev->ff, effect->type);
0356         if (combo_effect->type != effect_type) {
0357             if (combo_effect->type != 0) {
0358                 __clear_bit(i, effect_handled);
0359                 continue;
0360             }
0361             combo_effect->type = effect_type;
0362         }
0363
0364         if (__test_and_clear_bit(FF_EFFECT_ABORTING, &state->flags)) {
0365             __clear_bit(FF_EFFECT_PLAYING, &state->flags);
0366             __clear_bit(FF_EFFECT_STARTED, &state->flags);
0367         } else if (effect->replay.length &&
0368                time_after_eq(jiffies, state->stop_at)) {
0369
0370             __clear_bit(FF_EFFECT_PLAYING, &state->flags);
0371
0372             if (--state->count <= 0) {
0373                 __clear_bit(FF_EFFECT_STARTED, &state->flags);
0374             } else {
0375                 state->play_at = jiffies +
0376                     msecs_to_jiffies(effect->replay.delay);
0377                 state->stop_at = state->play_at +
0378                     msecs_to_jiffies(effect->replay.length);
0379             }
0380         } else {
0381             __set_bit(FF_EFFECT_PLAYING, &state->flags);
0382             state->adj_at = jiffies;
0383             ml_combine_effects(combo_effect, state, ml->gain);
0384         }
0385     }
0386
0387     return combo_effect->type != 0;
0388 }
0389
0390 static void ml_play_effects(struct ml_device *ml)
0391 {
0392     struct ff_effect effect;
0393     DECLARE_BITMAP(handled_bm, FF_MEMLESS_EFFECTS);
0394
0395     memset(handled_bm, 0, sizeof(handled_bm));
0396
0397     while (ml_get_combo_effect(ml, handled_bm, &effect))
0398         ml->play_effect(ml->dev, ml->private, &effect);
0399
0400     ml_schedule_timer(ml);
0401 }
0402
0403 static void ml_effect_timer(struct timer_list *t)
0404 {
0405     struct ml_device *ml = from_timer(ml, t, timer);
0406     struct input_dev *dev = ml->dev;
0407     unsigned long flags;
0408
0409     pr_debug("timer: updating effects\n");
0410
0411     spin_lock_irqsave(&dev->event_lock, flags);
0412     ml_play_effects(ml);
0413     spin_unlock_irqrestore(&dev->event_lock, flags);
0414 }
0415
0416 /*
0417  * Sets requested gain for FF effects. Called with dev->event_lock held.
0418  */
0419 static void ml_ff_set_gain(struct input_dev *dev, u16 gain)
0420 {
0421     struct ml_device *ml = dev->ff->private;
0422     int i;
0423
0424     ml->gain = gain;
0425
0426     for (i = 0; i < FF_MEMLESS_EFFECTS; i++)
0427         __clear_bit(FF_EFFECT_PLAYING, &ml->states[i].flags);
0428
0429     ml_play_effects(ml);
0430 }
0431
0432 /*
0433  * Start/stop specified FF effect. Called with dev->event_lock held.
0434  */
0435 static int ml_ff_playback(struct input_dev *dev, int effect_id, int value)
0436 {
0437     struct ml_device *ml = dev->ff->private;
0438     struct ml_effect_state *state = &ml->states[effect_id];
0439
0440     if (value > 0) {
0441         pr_debug("initiated play\n");
0442
0443         __set_bit(FF_EFFECT_STARTED, &state->flags);
0444         state->count = value;
0445         state->play_at = jiffies +
0446                  msecs_to_jiffies(state->effect->replay.delay);
0447         state->stop_at = state->play_at +
0448                  msecs_to_jiffies(state->effect->replay.length);
0449         state->adj_at = state->play_at;
0450
0451     } else {
0452         pr_debug("initiated stop\n");
0453
0454         if (test_bit(FF_EFFECT_PLAYING, &state->flags))
0455             __set_bit(FF_EFFECT_ABORTING, &state->flags);
0456         else
0457             __clear_bit(FF_EFFECT_STARTED, &state->flags);
0458     }
0459
0460     ml_play_effects(ml);
0461
0462     return 0;
0463 }
0464
0465 static int ml_ff_upload(struct input_dev *dev,
0466             struct ff_effect *effect, struct ff_effect *old)
0467 {
0468     struct ml_device *ml = dev->ff->private;
0469     struct ml_effect_state *state = &ml->states[effect->id];
0470
0471     spin_lock_irq(&dev->event_lock);
0472
0473     if (test_bit(FF_EFFECT_STARTED, &state->flags)) {
0474         __clear_bit(FF_EFFECT_PLAYING, &state->flags);
0475         state->play_at = jiffies +
0476                  msecs_to_jiffies(state->effect->replay.delay);
0477         state->stop_at = state->play_at +
0478                  msecs_to_jiffies(state->effect->replay.length);
0479         state->adj_at = state->play_at;
0480         ml_schedule_timer(ml);
0481     }
0482
0483     spin_unlock_irq(&dev->event_lock);
0484
0485     return 0;
0486 }
0487
0488 static void ml_ff_destroy(struct ff_device *ff)
0489 {
0490     struct ml_device *ml = ff->private;
0491
0492     /*
0493      * Even though we stop all playing effects when tearing down
0494      * an input device (via input_device_flush() that calls into
0495      * input_ff_flush() that stops and erases all effects), we
0496      * do not actually stop the timer, and therefore we should
0497      * do it here.
0498      */
0499     del_timer_sync(&ml->timer);
0500
0501     kfree(ml->private);
0502 }
0503
0504 /**
0505  * input_ff_create_memless() - create memoryless force-feedback device
0506  * @dev: input device supporting force-feedback
0507  * @data: driver-specific data to be passed into @play_effect
0508  * @play_effect: driver-specific method for playing FF effect
0509  */
0510 int input_ff_create_memless(struct input_dev *dev, void *data,
0511         int (*play_effect)(struct input_dev *, void *, struct ff_effect *))
0512 {
0513     struct ml_device *ml;
0514     struct ff_device *ff;
0515     int error;
0516     int i;
0517
0518     ml = kzalloc(sizeof(struct ml_device), GFP_KERNEL);
0519     if (!ml)
0520         return -ENOMEM;
0521
0522     ml->dev = dev;
0523     ml->private = data;
0524     ml->play_effect = play_effect;
0525     ml->gain = 0xffff;
0526     timer_setup(&ml->timer, ml_effect_timer, 0);
0527
0528     set_bit(FF_GAIN, dev->ffbit);
0529
0530     error = input_ff_create(dev, FF_MEMLESS_EFFECTS);
0531     if (error) {
0532         kfree(ml);
0533         return error;
0534     }
0535
0536     ff = dev->ff;
0537     ff->private = ml;
0538     ff->upload = ml_ff_upload;
0539     ff->playback = ml_ff_playback;
0540     ff->set_gain = ml_ff_set_gain;
0541     ff->destroy = ml_ff_destroy;
0542
0543     /* we can emulate periodic effects with RUMBLE */
0544     if (test_bit(FF_RUMBLE, ff->ffbit)) {
0545         set_bit(FF_PERIODIC, dev->ffbit);
0546         set_bit(FF_SINE, dev->ffbit);
0547         set_bit(FF_TRIANGLE, dev->ffbit);
0548         set_bit(FF_SQUARE, dev->ffbit);
0549     }
0550
0551     for (i = 0; i < FF_MEMLESS_EFFECTS; i++)
0552         ml->states[i].effect = &ff->effects[i];
0553
0554     return 0;
0555 }
0556 EXPORT_SYMBOL_GPL(input_ff_create_memless);