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ff-memless.c

/*
 *  Force feedback support for memoryless devices
 *
 *  Copyright (c) 2006 Anssi Hannula <anssi.hannula@gmail.com>
 *  Copyright (c) 2006 Dmitry Torokhov <dtor@mail.ru>
 */

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

/* #define DEBUG */

#define debug(format, arg...) pr_debug("ff-memless: " format "\n", ## arg)

#include <linux/input.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/jiffies.h>

#include "fixp-arith.h"

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Anssi Hannula <anssi.hannula@gmail.com>");
MODULE_DESCRIPTION("Force feedback support for memoryless devices");

/* Number of effects handled with memoryless devices */
#define FF_MEMLESS_EFFECTS    16

/* Envelope update interval in ms */
#define FF_ENVELOPE_INTERVAL  50

#define FF_EFFECT_STARTED     0
#define FF_EFFECT_PLAYING     1
#define FF_EFFECT_ABORTING    2

struct ml_effect_state {
      struct ff_effect *effect;
      unsigned long flags;    /* effect state (STARTED, PLAYING, etc) */
      int count;        /* loop count of the effect */
      unsigned long play_at;  /* start time */
      unsigned long stop_at;  /* stop time */
      unsigned long adj_at;   /* last time the effect was sent */
};

struct ml_device {
      void *private;
      struct ml_effect_state states[FF_MEMLESS_EFFECTS];
      int gain;
      struct timer_list timer;
      spinlock_t timer_lock;
      struct input_dev *dev;

      int (*play_effect)(struct input_dev *dev, void *data,
                     struct ff_effect *effect);
};

static const struct ff_envelope *get_envelope(const struct ff_effect *effect)
{
      static const struct ff_envelope empty_envelope;

      switch (effect->type) {
            case FF_PERIODIC:
                  return &effect->u.periodic.envelope;
            case FF_CONSTANT:
                  return &effect->u.constant.envelope;
            default:
                  return &empty_envelope;
      }
}

/*
 * Check for the next time envelope requires an update on memoryless devices
 */
static unsigned long calculate_next_time(struct ml_effect_state *state)
{
      const struct ff_envelope *envelope = get_envelope(state->effect);
      unsigned long attack_stop, fade_start, next_fade;

      if (envelope->attack_length) {
            attack_stop = state->play_at +
                  msecs_to_jiffies(envelope->attack_length);
            if (time_before(state->adj_at, attack_stop))
                  return state->adj_at +
                              msecs_to_jiffies(FF_ENVELOPE_INTERVAL);
      }

      if (state->effect->replay.length) {
            if (envelope->fade_length) {
                  /* check when fading should start */
                  fade_start = state->stop_at -
                              msecs_to_jiffies(envelope->fade_length);

                  if (time_before(state->adj_at, fade_start))
                        return fade_start;

                  /* already fading, advance to next checkpoint */
                  next_fade = state->adj_at +
                              msecs_to_jiffies(FF_ENVELOPE_INTERVAL);
                  if (time_before(next_fade, state->stop_at))
                        return next_fade;
            }

            return state->stop_at;
      }

      return state->play_at;
}

static void ml_schedule_timer(struct ml_device *ml)
{
      struct ml_effect_state *state;
      unsigned long now = jiffies;
      unsigned long earliest = 0;
      unsigned long next_at;
      int events = 0;
      int i;

      debug("calculating next timer");

      for (i = 0; i < FF_MEMLESS_EFFECTS; i++) {

            state = &ml->states[i];

            if (!test_bit(FF_EFFECT_STARTED, &state->flags))
                  continue;

            if (test_bit(FF_EFFECT_PLAYING, &state->flags))
                  next_at = calculate_next_time(state);
            else
                  next_at = state->play_at;

            if (time_before_eq(now, next_at) &&
                (++events == 1 || time_before(next_at, earliest)))
                  earliest = next_at;
      }

      if (!events) {
            debug("no actions");
            del_timer(&ml->timer);
      } else {
            debug("timer set");
            mod_timer(&ml->timer, earliest);
      }
}

/*
 * Apply an envelope to a value
 */
static int apply_envelope(struct ml_effect_state *state, int value,
                    struct ff_envelope *envelope)
{
      struct ff_effect *effect = state->effect;
      unsigned long now = jiffies;
      int time_from_level;
      int time_of_envelope;
      int envelope_level;
      int difference;

      if (envelope->attack_length &&
          time_before(now,
                  state->play_at + msecs_to_jiffies(envelope->attack_length))) {
            debug("value = 0x%x, attack_level = 0x%x", value,
                  envelope->attack_level);
            time_from_level = jiffies_to_msecs(now - state->play_at);
            time_of_envelope = envelope->attack_length;
            envelope_level = min_t(__s16, envelope->attack_level, 0x7fff);

      } else if (envelope->fade_length && effect->replay.length &&
               time_after(now,
                        state->stop_at - msecs_to_jiffies(envelope->fade_length)) &&
               time_before(now, state->stop_at)) {
            time_from_level = jiffies_to_msecs(state->stop_at - now);
            time_of_envelope = envelope->fade_length;
            envelope_level = min_t(__s16, envelope->fade_level, 0x7fff);
      } else
            return value;

      difference = abs(value) - envelope_level;

      debug("difference = %d", difference);
      debug("time_from_level = 0x%x", time_from_level);
      debug("time_of_envelope = 0x%x", time_of_envelope);

      difference = difference * time_from_level / time_of_envelope;

      debug("difference = %d", difference);

      return value < 0 ?
            -(difference + envelope_level) : (difference + envelope_level);
}

/*
 * Return the type the effect has to be converted into (memless devices)
 */
static int get_compatible_type(struct ff_device *ff, int effect_type)
{

      if (test_bit(effect_type, ff->ffbit))
            return effect_type;

      if (effect_type == FF_PERIODIC && test_bit(FF_RUMBLE, ff->ffbit))
            return FF_RUMBLE;

      printk(KERN_ERR
             "ff-memless: invalid type in get_compatible_type()\n");

      return 0;
}

/*
 * Combine two effects and apply gain.
 */
static void ml_combine_effects(struct ff_effect *effect,
                         struct ml_effect_state *state,
                         int gain)
{
      struct ff_effect *new = state->effect;
      unsigned int strong, weak, i;
      int x, y;
      fixp_t level;

      switch (new->type) {
      case FF_CONSTANT:
            i = new->direction * 360 / 0xffff;
            level = fixp_new16(apply_envelope(state,
                              new->u.constant.level,
                              &new->u.constant.envelope));
            x = fixp_mult(fixp_sin(i), level) * gain / 0xffff;
            y = fixp_mult(-fixp_cos(i), level) * gain / 0xffff;
            /*
             * here we abuse ff_ramp to hold x and y of constant force
             * If in future any driver wants something else than x and y
             * in s8, this should be changed to something more generic
             */
            effect->u.ramp.start_level =
                  max(min(effect->u.ramp.start_level + x, 0x7f), -0x80);
            effect->u.ramp.end_level =
                  max(min(effect->u.ramp.end_level + y, 0x7f), -0x80);
            break;

      case FF_RUMBLE:
            strong = new->u.rumble.strong_magnitude * gain / 0xffff;
            weak = new->u.rumble.weak_magnitude * gain / 0xffff;
            effect->u.rumble.strong_magnitude =
                  min(strong + effect->u.rumble.strong_magnitude,
                      0xffffU);
            effect->u.rumble.weak_magnitude =
                  min(weak + effect->u.rumble.weak_magnitude, 0xffffU);
            break;

      case FF_PERIODIC:
            i = apply_envelope(state, abs(new->u.periodic.magnitude),
                           &new->u.periodic.envelope);

            /* here we also scale it 0x7fff => 0xffff */
            i = i * gain / 0x7fff;

            effect->u.rumble.strong_magnitude =
                  min(i + effect->u.rumble.strong_magnitude, 0xffffU);
            effect->u.rumble.weak_magnitude =
                  min(i + effect->u.rumble.weak_magnitude, 0xffffU);
            break;

      default:
            printk(KERN_ERR "ff-memless: invalid type in ml_combine_effects()\n");
            break;
      }

}


/*
 * Because memoryless devices have only one effect per effect type active
 * at one time we have to combine multiple effects into one
 */
static int ml_get_combo_effect(struct ml_device *ml,
                         unsigned long *effect_handled,
                         struct ff_effect *combo_effect)
{
      struct ff_effect *effect;
      struct ml_effect_state *state;
      int effect_type;
      int i;

      memset(combo_effect, 0, sizeof(struct ff_effect));

      for (i = 0; i < FF_MEMLESS_EFFECTS; i++) {
            if (__test_and_set_bit(i, effect_handled))
                  continue;

            state = &ml->states[i];
            effect = state->effect;

            if (!test_bit(FF_EFFECT_STARTED, &state->flags))
                  continue;

            if (time_before(jiffies, state->play_at))
                  continue;

            /*
             * here we have started effects that are either
             * currently playing (and may need be aborted)
             * or need to start playing.
             */
            effect_type = get_compatible_type(ml->dev->ff, effect->type);
            if (combo_effect->type != effect_type) {
                  if (combo_effect->type != 0) {
                        __clear_bit(i, effect_handled);
                        continue;
                  }
                  combo_effect->type = effect_type;
            }

            if (__test_and_clear_bit(FF_EFFECT_ABORTING, &state->flags)) {
                  __clear_bit(FF_EFFECT_PLAYING, &state->flags);
                  __clear_bit(FF_EFFECT_STARTED, &state->flags);
            } else if (effect->replay.length &&
                     time_after_eq(jiffies, state->stop_at)) {

                  __clear_bit(FF_EFFECT_PLAYING, &state->flags);

                  if (--state->count <= 0) {
                        __clear_bit(FF_EFFECT_STARTED, &state->flags);
                  } else {
                        state->play_at = jiffies +
                              msecs_to_jiffies(effect->replay.delay);
                        state->stop_at = state->play_at +
                              msecs_to_jiffies(effect->replay.length);
                  }
            } else {
                  __set_bit(FF_EFFECT_PLAYING, &state->flags);
                  state->adj_at = jiffies;
                  ml_combine_effects(combo_effect, state, ml->gain);
            }
      }

      return combo_effect->type != 0;
}

static void ml_play_effects(struct ml_device *ml)
{
      struct ff_effect effect;
      DECLARE_BITMAP(handled_bm, FF_MEMLESS_EFFECTS);

      memset(handled_bm, 0, sizeof(handled_bm));

      while (ml_get_combo_effect(ml, handled_bm, &effect))
            ml->play_effect(ml->dev, ml->private, &effect);

      ml_schedule_timer(ml);
}

static void ml_effect_timer(unsigned long timer_data)
{
      struct input_dev *dev = (struct input_dev *)timer_data;
      struct ml_device *ml = dev->ff->private;

      debug("timer: updating effects");

      spin_lock(&ml->timer_lock);
      ml_play_effects(ml);
      spin_unlock(&ml->timer_lock);
}

static void ml_ff_set_gain(struct input_dev *dev, u16 gain)
{
      struct ml_device *ml = dev->ff->private;
      int i;

      spin_lock_bh(&ml->timer_lock);

      ml->gain = gain;

      for (i = 0; i < FF_MEMLESS_EFFECTS; i++)
            __clear_bit(FF_EFFECT_PLAYING, &ml->states[i].flags);

      ml_play_effects(ml);

      spin_unlock_bh(&ml->timer_lock);
}

static int ml_ff_playback(struct input_dev *dev, int effect_id, int value)
{
      struct ml_device *ml = dev->ff->private;
      struct ml_effect_state *state = &ml->states[effect_id];

      spin_lock_bh(&ml->timer_lock);

      if (value > 0) {
            debug("initiated play");

            __set_bit(FF_EFFECT_STARTED, &state->flags);
            state->count = value;
            state->play_at = jiffies +
                         msecs_to_jiffies(state->effect->replay.delay);
            state->stop_at = state->play_at +
                         msecs_to_jiffies(state->effect->replay.length);
            state->adj_at = state->play_at;

            ml_schedule_timer(ml);

      } else {
            debug("initiated stop");

            if (test_bit(FF_EFFECT_PLAYING, &state->flags))
                  __set_bit(FF_EFFECT_ABORTING, &state->flags);
            else
                  __clear_bit(FF_EFFECT_STARTED, &state->flags);

            ml_play_effects(ml);
      }

      spin_unlock_bh(&ml->timer_lock);

      return 0;
}

static int ml_ff_upload(struct input_dev *dev,
                  struct ff_effect *effect, struct ff_effect *old)
{
      struct ml_device *ml = dev->ff->private;
      struct ml_effect_state *state = &ml->states[effect->id];

      spin_lock_bh(&ml->timer_lock);

      if (test_bit(FF_EFFECT_STARTED, &state->flags)) {
            __clear_bit(FF_EFFECT_PLAYING, &state->flags);
            state->play_at = jiffies +
                         msecs_to_jiffies(state->effect->replay.delay);
            state->stop_at = state->play_at +
                         msecs_to_jiffies(state->effect->replay.length);
            state->adj_at = state->play_at;
            ml_schedule_timer(ml);
      }

      spin_unlock_bh(&ml->timer_lock);

      return 0;
}

static void ml_ff_destroy(struct ff_device *ff)
{
      struct ml_device *ml = ff->private;

      kfree(ml->private);
}

/**
 * input_ff_create_memless() - create memoryless force-feedback device
 * @dev: input device supporting force-feedback
 * @data: driver-specific data to be passed into @play_effect
 * @play_effect: driver-specific method for playing FF effect
 */
int input_ff_create_memless(struct input_dev *dev, void *data,
            int (*play_effect)(struct input_dev *, void *, struct ff_effect *))
{
      struct ml_device *ml;
      struct ff_device *ff;
      int error;
      int i;

      ml = kzalloc(sizeof(struct ml_device), GFP_KERNEL);
      if (!ml)
            return -ENOMEM;

      ml->dev = dev;
      ml->private = data;
      ml->play_effect = play_effect;
      ml->gain = 0xffff;
      spin_lock_init(&ml->timer_lock);
      setup_timer(&ml->timer, ml_effect_timer, (unsigned long)dev);

      set_bit(FF_GAIN, dev->ffbit);

      error = input_ff_create(dev, FF_MEMLESS_EFFECTS);
      if (error) {
            kfree(ml);
            return error;
      }

      ff = dev->ff;
      ff->private = ml;
      ff->upload = ml_ff_upload;
      ff->playback = ml_ff_playback;
      ff->set_gain = ml_ff_set_gain;
      ff->destroy = ml_ff_destroy;

      /* we can emulate periodic effects with RUMBLE */
      if (test_bit(FF_RUMBLE, ff->ffbit)) {
            set_bit(FF_PERIODIC, dev->ffbit);
            set_bit(FF_SINE, dev->ffbit);
            set_bit(FF_TRIANGLE, dev->ffbit);
            set_bit(FF_SQUARE, dev->ffbit);
      }

      for (i = 0; i < FF_MEMLESS_EFFECTS; i++)
            ml->states[i].effect = &ff->effects[i];

      return 0;
}
EXPORT_SYMBOL_GPL(input_ff_create_memless);

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