ff-memless.c

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/*
 *  Force feedback support for memoryless devices
 *
 *  Copyright (c) 2006 Anssi Hannula <[email protected]>
 *  Copyright (c) 2006 Dmitry Torokhov <[email protected]>
 */

/*
 * 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 pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/slab.h>
#include <linux/input.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/jiffies.h>
#include <linux/fixp-arith.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Anssi Hannula <[email protected]>");
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;
    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;

    pr_debug("calculating next timer\n");

    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) {
        pr_debug("no actions\n");
        del_timer(&ml->timer);
    } else {
        pr_debug("timer set\n");
        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))) {
        pr_debug("value = 0x%x, attack_level = 0x%x\n",
             value, envelope->attack_level);
        time_from_level = jiffies_to_msecs(now - state->play_at);
        time_of_envelope = envelope->attack_length;
        envelope_level = min_t(u16, 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(u16, envelope->fade_level, 0x7fff);
    } else
        return value;

    difference = abs(value) - envelope_level;

    pr_debug("difference = %d\n", difference);
    pr_debug("time_from_level = 0x%x\n", time_from_level);
    pr_debug("time_of_envelope = 0x%x\n", time_of_envelope);

    difference = difference * time_from_level / time_of_envelope;

    pr_debug("difference = %d\n", 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;

    pr_err("invalid type in get_compatible_type()\n");

    return 0;
}

/*
 * Only left/right direction should be used (under/over 0x8000) for
 * forward/reverse motor direction (to keep calculation fast & simple).
 */
static u16 ml_calculate_direction(u16 direction, u16 force,
                  u16 new_direction, u16 new_force)
{
    if (!force)
        return new_direction;
    if (!new_force)
        return direction;
    return (((u32)(direction >> 1) * force +
         (new_direction >> 1) * new_force) /
        (force + new_force)) << 1;
}

/*
 * 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 =
            clamp_val(effect->u.ramp.start_level + x, -0x80, 0x7f);
        effect->u.ramp.end_level =
            clamp_val(effect->u.ramp.end_level + y, -0x80, 0x7f);
        break;

    case FF_RUMBLE:
        strong = (u32)new->u.rumble.strong_magnitude * gain / 0xffff;
        weak = (u32)new->u.rumble.weak_magnitude * gain / 0xffff;

        if (effect->u.rumble.strong_magnitude + strong)
            effect->direction = ml_calculate_direction(
                effect->direction,
                effect->u.rumble.strong_magnitude,
                new->direction, strong);
        else if (effect->u.rumble.weak_magnitude + weak)
            effect->direction = ml_calculate_direction(
                effect->direction,
                effect->u.rumble.weak_magnitude,
                new->direction, weak);
        else
            effect->direction = 0;
        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;

        if (effect->u.rumble.strong_magnitude + i)
            effect->direction = ml_calculate_direction(
                effect->direction,
                effect->u.rumble.strong_magnitude,
                new->direction, i);
        else
            effect->direction = 0;
        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:
        pr_err("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;
    unsigned long flags;

    pr_debug("timer: updating effects\n");

    spin_lock_irqsave(&dev->event_lock, flags);
    ml_play_effects(ml);
    spin_unlock_irqrestore(&dev->event_lock, flags);
}

/*
 * Sets requested gain for FF effects. Called with dev->event_lock held.
 */
static void ml_ff_set_gain(struct input_dev *dev, u16 gain)
{
    struct ml_device *ml = dev->ff->private;
    int i;

    ml->gain = gain;

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

    ml_play_effects(ml);
}

/*
 * Start/stop specified FF effect. Called with dev->event_lock held.
 */
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];

    if (value > 0) {
        pr_debug("initiated play\n");

        __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;

    } else {
        pr_debug("initiated stop\n");

        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);

    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_irq(&dev->event_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_irq(&dev->event_lock);

    return 0;
}

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

    kfree(ml->private);
}

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;
    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);