ff-core.c

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/*
 *  Force feedback support for Linux input subsystem
 *
 *  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_BASENAME ": " fmt

#include <linux/input.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/slab.h>

/*
 * Check that the effect_id is a valid effect and whether the user
 * is the owner
 */
static int check_effect_access(struct ff_device *ff, int effect_id,
                struct file *file)
{
    if (effect_id < 0 || effect_id >= ff->max_effects ||
        !ff->effect_owners[effect_id])
        return -EINVAL;

    if (file && ff->effect_owners[effect_id] != file)
        return -EACCES;

    return 0;
}

/*
 * Checks whether 2 effects can be combined together
 */
static inline int check_effects_compatible(struct ff_effect *e1,
                       struct ff_effect *e2)
{
    return e1->type == e2->type &&
           (e1->type != FF_PERIODIC ||
        e1->u.periodic.waveform == e2->u.periodic.waveform);
}

/*
 * Convert an effect into compatible one
 */
static int compat_effect(struct ff_device *ff, struct ff_effect *effect)
{
    int magnitude;

    switch (effect->type) {
    case FF_RUMBLE:
        if (!test_bit(FF_PERIODIC, ff->ffbit))
            return -EINVAL;

        /*
         * calculate manginude of sine wave as average of rumble's
         * 2/3 of strong magnitude and 1/3 of weak magnitude
         */
        magnitude = effect->u.rumble.strong_magnitude / 3 +
                effect->u.rumble.weak_magnitude / 6;

        effect->type = FF_PERIODIC;
        effect->u.periodic.waveform = FF_SINE;
        effect->u.periodic.period = 50;
        effect->u.periodic.magnitude = max(magnitude, 0x7fff);
        effect->u.periodic.offset = 0;
        effect->u.periodic.phase = 0;
        effect->u.periodic.envelope.attack_length = 0;
        effect->u.periodic.envelope.attack_level = 0;
        effect->u.periodic.envelope.fade_length = 0;
        effect->u.periodic.envelope.fade_level = 0;

        return 0;

    default:
        /* Let driver handle conversion */
        return 0;
    }
}

int input_ff_upload(struct input_dev *dev, struct ff_effect *effect,
            struct file *file)
{
    struct ff_device *ff = dev->ff;
    struct ff_effect *old;
    int ret = 0;
    int id;

    if (!test_bit(EV_FF, dev->evbit))
        return -ENOSYS;

    if (effect->type < FF_EFFECT_MIN || effect->type > FF_EFFECT_MAX ||
        !test_bit(effect->type, dev->ffbit)) {
        pr_debug("invalid or not supported effect type in upload\n");
        return -EINVAL;
    }

    if (effect->type == FF_PERIODIC &&
        (effect->u.periodic.waveform < FF_WAVEFORM_MIN ||
         effect->u.periodic.waveform > FF_WAVEFORM_MAX ||
         !test_bit(effect->u.periodic.waveform, dev->ffbit))) {
        pr_debug("invalid or not supported wave form in upload\n");
        return -EINVAL;
    }

    if (!test_bit(effect->type, ff->ffbit)) {
        ret = compat_effect(ff, effect);
        if (ret)
            return ret;
    }

    mutex_lock(&ff->mutex);

    if (effect->id == -1) {
        for (id = 0; id < ff->max_effects; id++)
            if (!ff->effect_owners[id])
                break;

        if (id >= ff->max_effects) {
            ret = -ENOSPC;
            goto out;
        }

        effect->id = id;
        old = NULL;

    } else {
        id = effect->id;

        ret = check_effect_access(ff, id, file);
        if (ret)
            goto out;

        old = &ff->effects[id];

        if (!check_effects_compatible(effect, old)) {
            ret = -EINVAL;
            goto out;
        }
    }

    ret = ff->upload(dev, effect, old);
    if (ret)
        goto out;

    spin_lock_irq(&dev->event_lock);
    ff->effects[id] = *effect;
    ff->effect_owners[id] = file;
    spin_unlock_irq(&dev->event_lock);

 out:
    mutex_unlock(&ff->mutex);
    return ret;
}
EXPORT_SYMBOL_GPL(input_ff_upload);

/*
 * Erases the effect if the requester is also the effect owner. The mutex
 * should already be locked before calling this function.
 */
static int erase_effect(struct input_dev *dev, int effect_id,
            struct file *file)
{
    struct ff_device *ff = dev->ff;
    int error;

    error = check_effect_access(ff, effect_id, file);
    if (error)
        return error;

    spin_lock_irq(&dev->event_lock);
    ff->playback(dev, effect_id, 0);
    ff->effect_owners[effect_id] = NULL;
    spin_unlock_irq(&dev->event_lock);

    if (ff->erase) {
        error = ff->erase(dev, effect_id);
        if (error) {
            spin_lock_irq(&dev->event_lock);
            ff->effect_owners[effect_id] = file;
            spin_unlock_irq(&dev->event_lock);

            return error;
        }
    }

    return 0;
}

int input_ff_erase(struct input_dev *dev, int effect_id, struct file *file)
{
    struct ff_device *ff = dev->ff;
    int ret;

    if (!test_bit(EV_FF, dev->evbit))
        return -ENOSYS;

    mutex_lock(&ff->mutex);
    ret = erase_effect(dev, effect_id, file);
    mutex_unlock(&ff->mutex);

    return ret;
}
EXPORT_SYMBOL_GPL(input_ff_erase);

/*
 * flush_effects - erase all effects owned by a file handle
 */
static int flush_effects(struct input_dev *dev, struct file *file)
{
    struct ff_device *ff = dev->ff;
    int i;

    pr_debug("flushing now\n");

    mutex_lock(&ff->mutex);

    for (i = 0; i < ff->max_effects; i++)
        erase_effect(dev, i, file);

    mutex_unlock(&ff->mutex);

    return 0;
}

int input_ff_event(struct input_dev *dev, unsigned int type,
           unsigned int code, int value)
{
    struct ff_device *ff = dev->ff;

    if (type != EV_FF)
        return 0;

    switch (code) {
    case FF_GAIN:
        if (!test_bit(FF_GAIN, dev->ffbit) || value > 0xffff)
            break;

        ff->set_gain(dev, value);
        break;

    case FF_AUTOCENTER:
        if (!test_bit(FF_AUTOCENTER, dev->ffbit) || value > 0xffff)
            break;

        ff->set_autocenter(dev, value);
        break;

    default:
        if (check_effect_access(ff, code, NULL) == 0)
            ff->playback(dev, code, value);
        break;
    }

    return 0;
}
EXPORT_SYMBOL_GPL(input_ff_event);

int input_ff_create(struct input_dev *dev, unsigned int max_effects)
{
    struct ff_device *ff;
    size_t ff_dev_size;
    int i;

    if (!max_effects) {
        pr_err("cannot allocate device without any effects\n");
        return -EINVAL;
    }

    ff_dev_size = sizeof(struct ff_device) +
                max_effects * sizeof(struct file *);
    if (ff_dev_size < max_effects) /* overflow */
        return -EINVAL;

    ff = kzalloc(ff_dev_size, GFP_KERNEL);
    if (!ff)
        return -ENOMEM;

    ff->effects = kcalloc(max_effects, sizeof(struct ff_effect),
                  GFP_KERNEL);
    if (!ff->effects) {
        kfree(ff);
        return -ENOMEM;
    }

    ff->max_effects = max_effects;
    mutex_init(&ff->mutex);

    dev->ff = ff;
    dev->flush = flush_effects;
    dev->event = input_ff_event;
    __set_bit(EV_FF, dev->evbit);

    /* Copy "true" bits into ff device bitmap */
    for (i = 0; i <= FF_MAX; i++)
        if (test_bit(i, dev->ffbit))
            __set_bit(i, ff->ffbit);

    /* we can emulate RUMBLE with periodic effects */
    if (test_bit(FF_PERIODIC, ff->ffbit))
        __set_bit(FF_RUMBLE, dev->ffbit);

    return 0;
}
EXPORT_SYMBOL_GPL(input_ff_create);

void input_ff_destroy(struct input_dev *dev)
{
    struct ff_device *ff = dev->ff;

    __clear_bit(EV_FF, dev->evbit);
    if (ff) {
        if (ff->destroy)
            ff->destroy(ff);
        kfree(ff->private);
        kfree(ff->effects);
        kfree(ff);
        dev->ff = NULL;
    }
}
EXPORT_SYMBOL_GPL(input_ff_destroy);