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/*

 *  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);