drivers/input/ff-core.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Force feedback support for Linux input subsystem
   4  *
   5  *  Copyright (c) 2006 Anssi Hannula <anssi.hannula@gmail.com>
   6  *  Copyright (c) 2006 Dmitry Torokhov <dtor@mail.ru>
   7  */
   8
   9 /* #define DEBUG */
  10
  11 #include <linux/input.h>
  12 #include <linux/limits.h>
  13 #include <linux/module.h>
  14 #include <linux/mutex.h>
  15 #include <linux/overflow.h>
  16 #include <linux/sched.h>
  17 #include <linux/slab.h>
  18
  19 /*
  20  * Check that the effect_id is a valid effect and whether the user
  21  * is the owner
  22  */
  23 static int check_effect_access(struct ff_device *ff, int effect_id,
  24                                 struct file *file)
  25 {
  26         if (effect_id < 0 || effect_id >= ff->max_effects ||
  27             !ff->effect_owners[effect_id])
  28                 return -EINVAL;
  29
  30         if (file && ff->effect_owners[effect_id] != file)
  31                 return -EACCES;
  32
  33         return 0;
  34 }
  35
  36 /*
  37  * Checks whether 2 effects can be combined together
  38  */
  39 static inline int check_effects_compatible(struct ff_effect *e1,
  40                                            struct ff_effect *e2)
  41 {
  42         return e1->type == e2->type &&
  43                (e1->type != FF_PERIODIC ||
  44                 e1->u.periodic.waveform == e2->u.periodic.waveform);
  45 }
  46
  47 /*
  48  * Convert an effect into compatible one
  49  */
  50 static int compat_effect(struct ff_device *ff, struct ff_effect *effect)
  51 {
  52         int magnitude;
  53
  54         switch (effect->type) {
  55         case FF_RUMBLE:
  56                 if (!test_bit(FF_PERIODIC, ff->ffbit))
  57                         return -EINVAL;
  58
  59                 /*
  60                  * calculate magnitude of sine wave as average of rumble's
  61                  * 2/3 of strong magnitude and 1/3 of weak magnitude
  62                  */
  63                 magnitude = effect->u.rumble.strong_magnitude / 3 +
  64                             effect->u.rumble.weak_magnitude / 6;
  65
  66                 effect->type = FF_PERIODIC;
  67                 effect->u.periodic.waveform = FF_SINE;
  68                 effect->u.periodic.period = 50;
  69                 effect->u.periodic.magnitude = magnitude;
  70                 effect->u.periodic.offset = 0;
  71                 effect->u.periodic.phase = 0;
  72                 effect->u.periodic.envelope.attack_length = 0;
  73                 effect->u.periodic.envelope.attack_level = 0;
  74                 effect->u.periodic.envelope.fade_length = 0;
  75                 effect->u.periodic.envelope.fade_level = 0;
  76
  77                 return 0;
  78
  79         default:
  80                 /* Let driver handle conversion */
  81                 return 0;
  82         }
  83 }
  84
  85 /**
  86  * input_ff_upload() - upload effect into force-feedback device
  87  * @dev: input device
  88  * @effect: effect to be uploaded
  89  * @file: owner of the effect
  90  */
  91 int input_ff_upload(struct input_dev *dev, struct ff_effect *effect,
  92                     struct file *file)
  93 {
  94         struct ff_device *ff = dev->ff;
  95         struct ff_effect *old;
  96         int ret = 0;
  97         int id;
  98
  99         if (!test_bit(EV_FF, dev->evbit))
 100                 return -ENOSYS;
 101
 102         if (effect->type < FF_EFFECT_MIN || effect->type > FF_EFFECT_MAX ||
 103             !test_bit(effect->type, dev->ffbit)) {
 104                 dev_dbg(&dev->dev, "invalid or not supported effect type in upload\n");
 105                 return -EINVAL;
 106         }
 107
 108         if (effect->type == FF_PERIODIC &&
 109             (effect->u.periodic.waveform < FF_WAVEFORM_MIN ||
 110              effect->u.periodic.waveform > FF_WAVEFORM_MAX ||
 111              !test_bit(effect->u.periodic.waveform, dev->ffbit))) {
 112                 dev_dbg(&dev->dev, "invalid or not supported wave form in upload\n");
 113                 return -EINVAL;
 114         }
 115
 116         if (!test_bit(effect->type, ff->ffbit)) {
 117                 ret = compat_effect(ff, effect);
 118                 if (ret)
 119                         return ret;
 120         }
 121
 122         mutex_lock(&ff->mutex);
 123
 124         if (effect->id == -1) {
 125                 for (id = 0; id < ff->max_effects; id++)
 126                         if (!ff->effect_owners[id])
 127                                 break;
 128
 129                 if (id >= ff->max_effects) {
 130                         ret = -ENOSPC;
 131                         goto out;
 132                 }
 133
 134                 effect->id = id;
 135                 old = NULL;
 136
 137         } else {
 138                 id = effect->id;
 139
 140                 ret = check_effect_access(ff, id, file);
 141                 if (ret)
 142                         goto out;
 143
 144                 old = &ff->effects[id];
 145
 146                 if (!check_effects_compatible(effect, old)) {
 147                         ret = -EINVAL;
 148                         goto out;
 149                 }
 150         }
 151
 152         ret = ff->upload(dev, effect, old);
 153         if (ret)
 154                 goto out;
 155
 156         spin_lock_irq(&dev->event_lock);
 157         ff->effects[id] = *effect;
 158         ff->effect_owners[id] = file;
 159         spin_unlock_irq(&dev->event_lock);
 160
 161  out:
 162         mutex_unlock(&ff->mutex);
 163         return ret;
 164 }
 165 EXPORT_SYMBOL_GPL(input_ff_upload);
 166
 167 /*
 168  * Erases the effect if the requester is also the effect owner. The mutex
 169  * should already be locked before calling this function.
 170  */
 171 static int erase_effect(struct input_dev *dev, int effect_id,
 172                         struct file *file)
 173 {
 174         struct ff_device *ff = dev->ff;
 175         int error;
 176
 177         error = check_effect_access(ff, effect_id, file);
 178         if (error)
 179                 return error;
 180
 181         spin_lock_irq(&dev->event_lock);
 182         ff->playback(dev, effect_id, 0);
 183         ff->effect_owners[effect_id] = NULL;
 184         spin_unlock_irq(&dev->event_lock);
 185
 186         if (ff->erase) {
 187                 error = ff->erase(dev, effect_id);
 188                 if (error) {
 189                         spin_lock_irq(&dev->event_lock);
 190                         ff->effect_owners[effect_id] = file;
 191                         spin_unlock_irq(&dev->event_lock);
 192
 193                         return error;
 194                 }
 195         }
 196
 197         return 0;
 198 }
 199
 200 /**
 201  * input_ff_erase - erase a force-feedback effect from device
 202  * @dev: input device to erase effect from
 203  * @effect_id: id of the effect to be erased
 204  * @file: purported owner of the request
 205  *
 206  * This function erases a force-feedback effect from specified device.
 207  * The effect will only be erased if it was uploaded through the same
 208  * file handle that is requesting erase.
 209  */
 210 int input_ff_erase(struct input_dev *dev, int effect_id, struct file *file)
 211 {
 212         struct ff_device *ff = dev->ff;
 213         int ret;
 214
 215         if (!test_bit(EV_FF, dev->evbit))
 216                 return -ENOSYS;
 217
 218         mutex_lock(&ff->mutex);
 219         ret = erase_effect(dev, effect_id, file);
 220         mutex_unlock(&ff->mutex);
 221
 222         return ret;
 223 }
 224 EXPORT_SYMBOL_GPL(input_ff_erase);
 225
 226 /*
 227  * input_ff_flush - erase all effects owned by a file handle
 228  * @dev: input device to erase effect from
 229  * @file: purported owner of the effects
 230  *
 231  * This function erases all force-feedback effects associated with
 232  * the given owner from specified device. Note that @file may be %NULL,
 233  * in which case all effects will be erased.
 234  */
 235 int input_ff_flush(struct input_dev *dev, struct file *file)
 236 {
 237         struct ff_device *ff = dev->ff;
 238         int i;
 239
 240         dev_dbg(&dev->dev, "flushing now\n");
 241
 242         mutex_lock(&ff->mutex);
 243
 244         for (i = 0; i < ff->max_effects; i++)
 245                 erase_effect(dev, i, file);
 246
 247         mutex_unlock(&ff->mutex);
 248
 249         return 0;
 250 }
 251 EXPORT_SYMBOL_GPL(input_ff_flush);
 252
 253 /**
 254  * input_ff_event() - generic handler for force-feedback events
 255  * @dev: input device to send the effect to
 256  * @type: event type (anything but EV_FF is ignored)
 257  * @code: event code
 258  * @value: event value
 259  */
 260 int input_ff_event(struct input_dev *dev, unsigned int type,
 261                    unsigned int code, int value)
 262 {
 263         struct ff_device *ff = dev->ff;
 264
 265         if (type != EV_FF)
 266                 return 0;
 267
 268         switch (code) {
 269         case FF_GAIN:
 270                 if (!test_bit(FF_GAIN, dev->ffbit) || value > 0xffffU)
 271                         break;
 272
 273                 ff->set_gain(dev, value);
 274                 break;
 275
 276         case FF_AUTOCENTER:
 277                 if (!test_bit(FF_AUTOCENTER, dev->ffbit) || value > 0xffffU)
 278                         break;
 279
 280                 ff->set_autocenter(dev, value);
 281                 break;
 282
 283         default:
 284                 if (check_effect_access(ff, code, NULL) == 0)
 285                         ff->playback(dev, code, value);
 286                 break;
 287         }
 288
 289         return 0;
 290 }
 291 EXPORT_SYMBOL_GPL(input_ff_event);
 292
 293 /**
 294  * input_ff_create() - create force-feedback device
 295  * @dev: input device supporting force-feedback
 296  * @max_effects: maximum number of effects supported by the device
 297  *
 298  * This function allocates all necessary memory for a force feedback
 299  * portion of an input device and installs all default handlers.
 300  * @dev->ffbit should be already set up before calling this function.
 301  * Once ff device is created you need to setup its upload, erase,
 302  * playback and other handlers before registering input device
 303  */
 304 int input_ff_create(struct input_dev *dev, unsigned int max_effects)
 305 {
 306         struct ff_device *ff;
 307         size_t ff_dev_size;
 308         int i;
 309
 310         if (!max_effects) {
 311                 dev_err(&dev->dev, "cannot allocate device without any effects\n");
 312                 return -EINVAL;
 313         }
 314
 315         if (max_effects > FF_MAX_EFFECTS) {
 316                 dev_err(&dev->dev, "cannot allocate more than FF_MAX_EFFECTS effects\n");
 317                 return -EINVAL;
 318         }
 319
 320         ff_dev_size = struct_size(ff, effect_owners, max_effects);
 321         if (ff_dev_size == SIZE_MAX) /* overflow */
 322                 return -EINVAL;
 323
 324         ff = kzalloc(ff_dev_size, GFP_KERNEL);
 325         if (!ff)
 326                 return -ENOMEM;
 327
 328         ff->effects = kcalloc(max_effects, sizeof(struct ff_effect),
 329                               GFP_KERNEL);
 330         if (!ff->effects) {
 331                 kfree(ff);
 332                 return -ENOMEM;
 333         }
 334
 335         ff->max_effects = max_effects;
 336         mutex_init(&ff->mutex);
 337
 338         dev->ff = ff;
 339         dev->flush = input_ff_flush;
 340         dev->event = input_ff_event;
 341         __set_bit(EV_FF, dev->evbit);
 342
 343         /* Copy "true" bits into ff device bitmap */
 344         for_each_set_bit(i, dev->ffbit, FF_CNT)
 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);