Logo Search packages:      
Sourcecode: linux version File versions  Download package

ff-core.c

/*
 *  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 debug(format, arg...) pr_debug("ff-core: " format "\n", ## arg)

#include <linux/input.h>
#include <linux/module.h>
#include <linux/mutex.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)) {
            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))) {
            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;

      ff->effects[id] = *effect;
      ff->effect_owners[id] = file;

 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;

      ff->playback(dev, effect_id, 0);

      if (ff->erase) {
            error = ff->erase(dev, effect_id);
            if (error)
                  return error;
      }

      ff->effect_owners[effect_id] = NULL;

      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;

      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;

      mutex_lock(&ff->mutex);

      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;
      }

      mutex_unlock(&ff->mutex);
      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, int max_effects)
{
      struct ff_device *ff;
      int i;

      if (!max_effects) {
            printk(KERN_ERR
                   "ff-core: cannot allocate device without any effects\n");
            return -EINVAL;
      }

      ff = kzalloc(sizeof(struct ff_device) +
                 max_effects * sizeof(struct file *), 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_free() - 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)
{
      clear_bit(EV_FF, dev->evbit);
      if (dev->ff) {
            if (dev->ff->destroy)
                  dev->ff->destroy(dev->ff);
            kfree(dev->ff->private);
            kfree(dev->ff);
            dev->ff = NULL;
      }
}
EXPORT_SYMBOL_GPL(input_ff_destroy);

Generated by  Doxygen 1.6.0   Back to index