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