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 #include <linux/input.h>
  27 #include <linux/module.h>
  28 #include <linux/mutex.h>
  29 #include <linux/sched.h>
  30 #include <linux/slab.h>
  31
  32 /*
  33  * Check that the effect_id is a valid effect and whether the user
  34  * is the owner
  35  */
  36 static int check_effect_access(struct ff_device *ff, int effect_id,
  37                                 struct file *file)
  38 {
  39         if (effect_id < 0 || effect_id >= ff->max_effects ||
  40             !ff->effect_owners[effect_id])
  41                 return -EINVAL;
  42
  43         if (file && ff->effect_owners[effect_id] != file)
  44                 return -EACCES;
  45
  46         return 0;
  47 }
  48
  49 /*
  50  * Checks whether 2 effects can be combined together
  51  */
  52 static inline int check_effects_compatible(struct ff_effect *e1,
  53                                            struct ff_effect *e2)
  54 {
  55         return e1->type == e2->type &&
  56                (e1->type != FF_PERIODIC ||
  57                 e1->u.periodic.waveform == e2->u.periodic.waveform);
  58 }
  59
  60 /*
  61  * Convert an effect into compatible one
  62  */
  63 static int compat_effect(struct ff_device *ff, struct ff_effect *effect)
  64 {
  65         int magnitude;
  66
  67         switch (effect->type) {
  68         case FF_RUMBLE:
  69                 if (!test_bit(FF_PERIODIC, ff->ffbit))
  70                         return -EINVAL;
  71
  72                 /*
  73                  * calculate magnitude of sine wave as average of rumble's
  74                  * 2/3 of strong magnitude and 1/3 of weak magnitude
  75                  */
  76                 magnitude = effect->u.rumble.strong_magnitude / 3 +
  77                             effect->u.rumble.weak_magnitude / 6;
  78
  79                 effect->type = FF_PERIODIC;
  80                 effect->u.periodic.waveform = FF_SINE;
  81                 effect->u.periodic.period = 50;
  82                 effect->u.periodic.magnitude = max(magnitude, 0x7fff);
  83                 effect->u.periodic.offset = 0;
  84                 effect->u.periodic.phase = 0;
  85                 effect->u.periodic.envelope.attack_length = 0;
  86                 effect->u.periodic.envelope.attack_level = 0;
  87                 effect->u.periodic.envelope.fade_length = 0;
  88                 effect->u.periodic.envelope.fade_level = 0;
  89
  90                 return 0;
  91
  92         default:
  93                 /* Let driver handle conversion */
  94                 return 0;
  95         }
  96 }
  97
  98 /**
  99  * input_ff_upload() - upload effect into force-feedback device
 100  * @dev: input device
 101  * @effect: effect to be uploaded
 102  * @file: owner of the effect
 103  */
 104 int input_ff_upload(struct input_dev *dev, struct ff_effect *effect,
 105                     struct file *file)
 106 {
 107         struct ff_device *ff = dev->ff;
 108         struct ff_effect *old;
 109         int ret = 0;
 110         int id;
 111
 112         if (!test_bit(EV_FF, dev->evbit))
 113                 return -ENOSYS;
 114
 115         if (effect->type < FF_EFFECT_MIN || effect->type > FF_EFFECT_MAX ||
 116             !test_bit(effect->type, dev->ffbit)) {
 117                 dev_dbg(&dev->dev, "invalid or not supported effect type in upload\n");
 118                 return -EINVAL;
 119         }
 120
 121         if (effect->type == FF_PERIODIC &&
 122             (effect->u.periodic.waveform < FF_WAVEFORM_MIN ||
 123              effect->u.periodic.waveform > FF_WAVEFORM_MAX ||
 124              !test_bit(effect->u.periodic.waveform, dev->ffbit))) {
 125                 dev_dbg(&dev->dev, "invalid or not supported wave form in upload\n");
 126                 return -EINVAL;
 127         }
 128
 129         if (!test_bit(effect->type, ff->ffbit)) {
 130                 ret = compat_effect(ff, effect);
 131                 if (ret)
 132                         return ret;
 133         }
 134
 135         mutex_lock(&ff->mutex);
 136
 137         if (effect->id == -1) {
 138                 for (id = 0; id < ff->max_effects; id++)
 139                         if (!ff->effect_owners[id])
 140                                 break;
 141
 142                 if (id >= ff->max_effects) {
 143                         ret = -ENOSPC;
 144                         goto out;
 145                 }
 146
 147                 effect->id = id;
 148                 old = NULL;
 149
 150         } else {
 151                 id = effect->id;
 152
 153                 ret = check_effect_access(ff, id, file);
 154                 if (ret)
 155                         goto out;
 156
 157                 old = &ff->effects[id];
 158
 159                 if (!check_effects_compatible(effect, old)) {
 160                         ret = -EINVAL;
 161                         goto out;
 162                 }
 163         }
 164
 165         ret = ff->upload(dev, effect, old);
 166         if (ret)
 167                 goto out;
 168
 169         spin_lock_irq(&dev->event_lock);
 170         ff->effects[id] = *effect;
 171         ff->effect_owners[id] = file;
 172         spin_unlock_irq(&dev->event_lock);
 173
 174  out:
 175         mutex_unlock(&ff->mutex);
 176         return ret;
 177 }
 178 EXPORT_SYMBOL_GPL(input_ff_upload);
 179
 180 /*
 181  * Erases the effect if the requester is also the effect owner. The mutex
 182  * should already be locked before calling this function.
 183  */
 184 static int erase_effect(struct input_dev *dev, int effect_id,
 185                         struct file *file)
 186 {
 187         struct ff_device *ff = dev->ff;
 188         int error;
 189
 190         error = check_effect_access(ff, effect_id, file);
 191         if (error)
 192                 return error;
 193
 194         spin_lock_irq(&dev->event_lock);
 195         ff->playback(dev, effect_id, 0);
 196         ff->effect_owners[effect_id] = NULL;
 197         spin_unlock_irq(&dev->event_lock);
 198
 199         if (ff->erase) {
 200                 error = ff->erase(dev, effect_id);
 201                 if (error) {
 202                         spin_lock_irq(&dev->event_lock);
 203                         ff->effect_owners[effect_id] = file;
 204                         spin_unlock_irq(&dev->event_lock);
 205
 206                         return error;
 207                 }
 208         }
 209
 210         return 0;
 211 }
 212
 213 /**
 214  * input_ff_erase - erase a force-feedback effect from device
 215  * @dev: input device to erase effect from
 216  * @effect_id: id of the effect to be erased
 217  * @file: purported owner of the request
 218  *
 219  * This function erases a force-feedback effect from specified device.
 220  * The effect will only be erased if it was uploaded through the same
 221  * file handle that is requesting erase.
 222  */
 223 int input_ff_erase(struct input_dev *dev, int effect_id, struct file *file)
 224 {
 225         struct ff_device *ff = dev->ff;
 226         int ret;
 227
 228         if (!test_bit(EV_FF, dev->evbit))
 229                 return -ENOSYS;
 230
 231         mutex_lock(&ff->mutex);
 232         ret = erase_effect(dev, effect_id, file);
 233         mutex_unlock(&ff->mutex);
 234
 235         return ret;
 236 }
 237 EXPORT_SYMBOL_GPL(input_ff_erase);
 238
 239 /*
 240  * flush_effects - erase all effects owned by a file handle
 241  */
 242 static int flush_effects(struct input_dev *dev, struct file *file)
 243 {
 244         struct ff_device *ff = dev->ff;
 245         int i;
 246
 247         dev_dbg(&dev->dev, "flushing now\n");
 248
 249         mutex_lock(&ff->mutex);
 250
 251         for (i = 0; i < ff->max_effects; i++)
 252                 erase_effect(dev, i, file);
 253
 254         mutex_unlock(&ff->mutex);
 255
 256         return 0;
 257 }
 258
 259 /**
 260  * input_ff_event() - generic handler for force-feedback events
 261  * @dev: input device to send the effect to
 262  * @type: event type (anything but EV_FF is ignored)
 263  * @code: event code
 264  * @value: event value
 265  */
 266 int input_ff_event(struct input_dev *dev, unsigned int type,
 267                    unsigned int code, int value)
 268 {
 269         struct ff_device *ff = dev->ff;
 270
 271         if (type != EV_FF)
 272                 return 0;
 273
 274         switch (code) {
 275         case FF_GAIN:
 276                 if (!test_bit(FF_GAIN, dev->ffbit) || value > 0xffffU)
 277                         break;
 278
 279                 ff->set_gain(dev, value);
 280                 break;
 281
 282         case FF_AUTOCENTER:
 283                 if (!test_bit(FF_AUTOCENTER, dev->ffbit) || value > 0xffffU)
 284                         break;
 285
 286                 ff->set_autocenter(dev, value);
 287                 break;
 288
 289         default:
 290                 if (check_effect_access(ff, code, NULL) == 0)
 291                         ff->playback(dev, code, value);
 292                 break;
 293         }
 294
 295         return 0;
 296 }
 297 EXPORT_SYMBOL_GPL(input_ff_event);
 298
 299 /**
 300  * input_ff_create() - create force-feedback device
 301  * @dev: input device supporting force-feedback
 302  * @max_effects: maximum number of effects supported by the device
 303  *
 304  * This function allocates all necessary memory for a force feedback
 305  * portion of an input device and installs all default handlers.
 306  * @dev->ffbit should be already set up before calling this function.
 307  * Once ff device is created you need to setup its upload, erase,
 308  * playback and other handlers before registering input device
 309  */
 310 int input_ff_create(struct input_dev *dev, unsigned int max_effects)
 311 {
 312         struct ff_device *ff;
 313         size_t ff_dev_size;
 314         int i;
 315
 316         if (!max_effects) {
 317                 dev_err(&dev->dev, "cannot allocate device without any effects\n");
 318                 return -EINVAL;
 319         }
 320
 321         if (max_effects > FF_MAX_EFFECTS) {
 322                 dev_err(&dev->dev, "cannot allocate more than FF_MAX_EFFECTS effects\n");
 323                 return -EINVAL;
 324         }
 325
 326         ff_dev_size = sizeof(struct ff_device) +
 327                                 max_effects * sizeof(struct file *);
 328         if (ff_dev_size < max_effects) /* overflow */
 329                 return -EINVAL;
 330
 331         ff = kzalloc(ff_dev_size, GFP_KERNEL);
 332         if (!ff)
 333                 return -ENOMEM;
 334
 335         ff->effects = kcalloc(max_effects, sizeof(struct ff_effect),
 336                               GFP_KERNEL);
 337         if (!ff->effects) {
 338                 kfree(ff);
 339                 return -ENOMEM;
 340         }
 341
 342         ff->max_effects = max_effects;
 343         mutex_init(&ff->mutex);
 344
 345         dev->ff = ff;
 346         dev->flush = flush_effects;
 347         dev->event = input_ff_event;
 348         __set_bit(EV_FF, dev->evbit);
 349
 350         /* Copy "true" bits into ff device bitmap */
 351         for_each_set_bit(i, dev->ffbit, FF_CNT)
 352                 __set_bit(i, ff->ffbit);
 353
 354         /* we can emulate RUMBLE with periodic effects */
 355         if (test_bit(FF_PERIODIC, ff->ffbit))
 356                 __set_bit(FF_RUMBLE, dev->ffbit);
 357
 358         return 0;
 359 }
 360 EXPORT_SYMBOL_GPL(input_ff_create);
 361
 362 /**
 363  * input_ff_destroy() - frees force feedback portion of input device
 364  * @dev: input device supporting force feedback
 365  *
 366  * This function is only needed in error path as input core will
 367  * automatically free force feedback structures when device is
 368  * destroyed.
 369  */
 370 void input_ff_destroy(struct input_dev *dev)
 371 {
 372         struct ff_device *ff = dev->ff;
 373
 374         __clear_bit(EV_FF, dev->evbit);
 375         if (ff) {
 376                 if (ff->destroy)
 377                         ff->destroy(ff);
 378                 kfree(ff->private);
 379                 kfree(ff->effects);
 380                 kfree(ff);
 381                 dev->ff = NULL;
 382         }
 383 }
 384 EXPORT_SYMBOL_GPL(input_ff_destroy);