drivers/input/ff-core.c

   1 /*
   2  *  Force feedback support for Linux input subsystem
   3  *
   4  *  Copyright (c) 2006 Anssi Hannula <anssi.hannula@gmail.com>
   5  *  Copyright (c) 2006 Dmitry Torokhov <dtor@mail.ru>
   6  */
   7
   8 /*
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  22  */
  23
  24 /* #define DEBUG */
  25
  26 #define debug(format, arg...) pr_debug("ff-core: " format "\n", ## arg)
  27
  28 #include <linux/input.h>
  29 #include <linux/module.h>
  30 #include <linux/mutex.h>
  31 #include <linux/sched.h>
  32
  33 /*
  34  * Check that the effect_id is a valid effect and whether the user
  35  * is the owner
  36  */
  37 static int check_effect_access(struct ff_device *ff, int effect_id,
  38                                 struct file *file)
  39 {
  40         if (effect_id < 0 || effect_id >= ff->max_effects ||
  41             !ff->effect_owners[effect_id])
  42                 return -EINVAL;
  43
  44         if (file && ff->effect_owners[effect_id] != file)
  45                 return -EACCES;
  46
  47         return 0;
  48 }
  49
  50 /*
  51  * Checks whether 2 effects can be combined together
  52  */
  53 static inline int check_effects_compatible(struct ff_effect *e1,
  54                                            struct ff_effect *e2)
  55 {
  56         return e1->type == e2->type &&
  57                (e1->type != FF_PERIODIC ||
  58                 e1->u.periodic.waveform == e2->u.periodic.waveform);
  59 }
  60
  61 /*
  62  * Convert an effect into compatible one
  63  */
  64 static int compat_effect(struct ff_device *ff, struct ff_effect *effect)
  65 {
  66         int magnitude;
  67
  68         switch (effect->type) {
  69         case FF_RUMBLE:
  70                 if (!test_bit(FF_PERIODIC, ff->ffbit))
  71                         return -EINVAL;
  72
  73                 /*
  74                  * calculate manginude of sine wave as average of rumble's
  75                  * 2/3 of strong magnitude and 1/3 of weak magnitude
  76                  */
  77                 magnitude = effect->u.rumble.strong_magnitude / 3 +
  78                             effect->u.rumble.weak_magnitude / 6;
  79
  80                 effect->type = FF_PERIODIC;
  81                 effect->u.periodic.waveform = FF_SINE;
  82                 effect->u.periodic.period = 50;
  83                 effect->u.periodic.magnitude = max(magnitude, 0x7fff);
  84                 effect->u.periodic.offset = 0;
  85                 effect->u.periodic.phase = 0;
  86                 effect->u.periodic.envelope.attack_length = 0;
  87                 effect->u.periodic.envelope.attack_level = 0;
  88                 effect->u.periodic.envelope.fade_length = 0;
  89                 effect->u.periodic.envelope.fade_level = 0;
  90
  91                 return 0;
  92
  93         default:
  94                 /* Let driver handle conversion */
  95                 return 0;
  96         }
  97 }
  98
  99 /**
 100  * input_ff_upload() - upload effect into force-feedback device
 101  * @dev: input device
 102  * @effect: effect to be uploaded
 103  * @file: owner of the effect
 104  */
 105 int input_ff_upload(struct input_dev *dev, struct ff_effect *effect,
 106                     struct file *file)
 107 {
 108         struct ff_device *ff = dev->ff;
 109         struct ff_effect *old;
 110         int ret = 0;
 111         int id;
 112
 113         if (!test_bit(EV_FF, dev->evbit))
 114                 return -ENOSYS;
 115
 116         if (effect->type < FF_EFFECT_MIN || effect->type > FF_EFFECT_MAX ||
 117             !test_bit(effect->type, dev->ffbit)) {
 118                 debug("invalid or not supported effect type in upload");
 119                 return -EINVAL;
 120         }
 121
 122         if (effect->type == FF_PERIODIC &&
 123             (effect->u.periodic.waveform < FF_WAVEFORM_MIN ||
 124              effect->u.periodic.waveform > FF_WAVEFORM_MAX ||
 125              !test_bit(effect->u.periodic.waveform, dev->ffbit))) {
 126                 debug("invalid or not supported wave form in upload");
 127                 return -EINVAL;
 128         }
 129
 130         if (!test_bit(effect->type, ff->ffbit)) {
 131                 ret = compat_effect(ff, effect);
 132                 if (ret)
 133                         return ret;
 134         }
 135
 136         mutex_lock(&ff->mutex);
 137
 138         if (effect->id == -1) {
 139                 for (id = 0; id < ff->max_effects; id++)
 140                      if (!ff->effect_owners[id])
 141                         break;
 142
 143                 if (id >= ff->max_effects) {
 144                         ret = -ENOSPC;
 145                         goto out;
 146                 }
 147
 148                 effect->id = id;
 149                 old = NULL;
 150
 151         } else {
 152                 id = effect->id;
 153
 154                 ret = check_effect_access(ff, id, file);
 155                 if (ret)
 156                         goto out;
 157
 158                 old = &ff->effects[id];
 159
 160                 if (!check_effects_compatible(effect, old)) {
 161                         ret = -EINVAL;
 162                         goto out;
 163                 }
 164         }
 165
 166         ret = ff->upload(dev, effect, old);
 167         if (ret)
 168                 goto out;
 169
 170         spin_lock_irq(&dev->event_lock);
 171         ff->effects[id] = *effect;
 172         ff->effect_owners[id] = file;
 173         spin_unlock_irq(&dev->event_lock);
 174
 175  out:
 176         mutex_unlock(&ff->mutex);
 177         return ret;
 178 }
 179 EXPORT_SYMBOL_GPL(input_ff_upload);
 180
 181 /*
 182  * Erases the effect if the requester is also the effect owner. The mutex
 183  * should already be locked before calling this function.
 184  */
 185 static int erase_effect(struct input_dev *dev, int effect_id,
 186                         struct file *file)
 187 {
 188         struct ff_device *ff = dev->ff;
 189         int error;
 190
 191         error = check_effect_access(ff, effect_id, file);
 192         if (error)
 193                 return error;
 194
 195         spin_lock_irq(&dev->event_lock);
 196         ff->playback(dev, effect_id, 0);
 197         ff->effect_owners[effect_id] = NULL;
 198         spin_unlock_irq(&dev->event_lock);
 199
 200         if (ff->erase) {
 201                 error = ff->erase(dev, effect_id);
 202                 if (error) {
 203                         spin_lock_irq(&dev->event_lock);
 204                         ff->effect_owners[effect_id] = file;
 205                         spin_unlock_irq(&dev->event_lock);
 206
 207                         return error;
 208                 }
 209         }
 210
 211         return 0;
 212 }
 213
 214 /**
 215  * input_ff_erase - erase a force-feedback effect from device
 216  * @dev: input device to erase effect from
 217  * @effect_id: id of the ffect to be erased
 218  * @file: purported owner of the request
 219  *
 220  * This function erases a force-feedback effect from specified device.
 221  * The effect will only be erased if it was uploaded through the same
 222  * file handle that is requesting erase.
 223  */
 224 int input_ff_erase(struct input_dev *dev, int effect_id, struct file *file)
 225 {
 226         struct ff_device *ff = dev->ff;
 227         int ret;
 228
 229         if (!test_bit(EV_FF, dev->evbit))
 230                 return -ENOSYS;
 231
 232         mutex_lock(&ff->mutex);
 233         ret = erase_effect(dev, effect_id, file);
 234         mutex_unlock(&ff->mutex);
 235
 236         return ret;
 237 }
 238 EXPORT_SYMBOL_GPL(input_ff_erase);
 239
 240 /*
 241  * flush_effects - erase all effects owned by a file handle
 242  */
 243 static int flush_effects(struct input_dev *dev, struct file *file)
 244 {
 245         struct ff_device *ff = dev->ff;
 246         int i;
 247
 248         debug("flushing now");
 249
 250         mutex_lock(&ff->mutex);
 251
 252         for (i = 0; i < ff->max_effects; i++)
 253                 erase_effect(dev, i, file);
 254
 255         mutex_unlock(&ff->mutex);
 256
 257         return 0;
 258 }
 259
 260 /**
 261  * input_ff_event() - generic handler for force-feedback events
 262  * @dev: input device to send the effect to
 263  * @type: event type (anything but EV_FF is ignored)
 264  * @code: event code
 265  * @value: event value
 266  */
 267 int input_ff_event(struct input_dev *dev, unsigned int type,
 268                    unsigned int code, int value)
 269 {
 270         struct ff_device *ff = dev->ff;
 271
 272         if (type != EV_FF)
 273                 return 0;
 274
 275         switch (code) {
 276         case FF_GAIN:
 277                 if (!test_bit(FF_GAIN, dev->ffbit) || value > 0xffff)
 278                         break;
 279
 280                 ff->set_gain(dev, value);
 281                 break;
 282
 283         case FF_AUTOCENTER:
 284                 if (!test_bit(FF_AUTOCENTER, dev->ffbit) || value > 0xffff)
 285                         break;
 286
 287                 ff->set_autocenter(dev, value);
 288                 break;
 289
 290         default:
 291                 if (check_effect_access(ff, code, NULL) == 0)
 292                         ff->playback(dev, code, value);
 293                 break;
 294         }
 295
 296         return 0;
 297 }
 298 EXPORT_SYMBOL_GPL(input_ff_event);
 299
 300 /**
 301  * input_ff_create() - create force-feedback device
 302  * @dev: input device supporting force-feedback
 303  * @max_effects: maximum number of effects supported by the device
 304  *
 305  * This function allocates all necessary memory for a force feedback
 306  * portion of an input device and installs all default handlers.
 307  * @dev->ffbit should be already set up before calling this function.
 308  * Once ff device is created you need to setup its upload, erase,
 309  * playback and other handlers before registering input device
 310  */
 311 int input_ff_create(struct input_dev *dev, int max_effects)
 312 {
 313         struct ff_device *ff;
 314         int i;
 315
 316         if (!max_effects) {
 317                 printk(KERN_ERR
 318                        "ff-core: cannot allocate device without any effects\n");
 319                 return -EINVAL;
 320         }
 321
 322         ff = kzalloc(sizeof(struct ff_device) +
 323                      max_effects * sizeof(struct file *), GFP_KERNEL);
 324         if (!ff)
 325                 return -ENOMEM;
 326
 327         ff->effects = kcalloc(max_effects, sizeof(struct ff_effect),
 328                               GFP_KERNEL);
 329         if (!ff->effects) {
 330                 kfree(ff);
 331                 return -ENOMEM;
 332         }
 333
 334         ff->max_effects = max_effects;
 335         mutex_init(&ff->mutex);
 336
 337         dev->ff = ff;
 338         dev->flush = flush_effects;
 339         dev->event = input_ff_event;
 340         __set_bit(EV_FF, dev->evbit);
 341
 342         /* Copy "true" bits into ff device bitmap */
 343         for (i = 0; i <= FF_MAX; i++)
 344                 if (test_bit(i, dev->ffbit))
 345                         __set_bit(i, ff->ffbit);
 346
 347         /* we can emulate RUMBLE with periodic effects */
 348         if (test_bit(FF_PERIODIC, ff->ffbit))
 349                 __set_bit(FF_RUMBLE, dev->ffbit);
 350
 351         return 0;
 352 }
 353 EXPORT_SYMBOL_GPL(input_ff_create);
 354
 355 /**
 356  * input_ff_destroy() - frees force feedback portion of input device
 357  * @dev: input device supporting force feedback
 358  *
 359  * This function is only needed in error path as input core will
 360  * automatically free force feedback structures when device is
 361  * destroyed.
 362  */
 363 void input_ff_destroy(struct input_dev *dev)
 364 {
 365         struct ff_device *ff = dev->ff;
 366
 367         __clear_bit(EV_FF, dev->evbit);
 368         if (ff) {
 369                 if (ff->destroy)
 370                         ff->destroy(ff);
 371                 kfree(ff->private);
 372                 kfree(ff->effects);
 373                 kfree(ff);
 374                 dev->ff = NULL;
 375         }
 376 }
 377 EXPORT_SYMBOL_GPL(input_ff_destroy);