/*
 *  Force feedback support for Linux input subsystem
 *
 *  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 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;
        }
}

/**
 * input_ff_upload() - upload effect into force-feedback device
 * @dev: input device
 * @effect: effect to be uploaded
 * @file: owner of the effect
 */
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;
}

/**
 * input_ff_erase - erase a force-feedback effect from device
 * @dev: input device to erase effect from
 * @effect_id: id of the ffect to be erased
 * @file: purported owner of the request
 *
 * This function erases a force-feedback effect from specified device.
 * The effect will only be erased if it was uploaded through the same
 * file handle that is requesting erase.
 */
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;
}

/**
 * input_ff_event() - generic handler for force-feedback events
 * @dev: input device to send the effect to
 * @type: event type (anything but EV_FF is ignored)
 * @code: event code
 * @value: event value
 */
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);

/**
 * input_ff_create() - create force-feedback device
 * @dev: input device supporting force-feedback
 * @max_effects: maximum number of effects supported by the device
 *
 * This function allocates all necessary memory for a force feedback
 * portion of an input device and installs all default handlers.
 * @dev->ffbit should be already set up before calling this function.
 * Once ff device is created you need to setup its upload, erase,
 * playback and other handlers before registering input device
 */
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);

/**
 * input_ff_destroy() - frees force feedback portion of input device
 * @dev: input device supporting force feedback
 *
 * This function is only needed in error path as input core will
 * automatically free force feedback structures when device is
 * destroyed.
 */
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);