/*
   *  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
  ");

  		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
  ");

  		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
  ");

  
  	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
  ");

  		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);