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 error;
  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                 error = compat_effect(ff, effect);
 118                 if (error)
 119                         return error;
 120         }
 121
 122         guard(mutex)(&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                         return -ENOSPC;
 131
 132                 effect->id = id;
 133                 old = NULL;
 134
 135         } else {
 136                 id = effect->id;
 137
 138                 error = check_effect_access(ff, id, file);
 139                 if (error)
 140                         return error;
 141
 142                 old = &ff->effects[id];
 143
 144                 if (!check_effects_compatible(effect, old))
 145                         return -EINVAL;
 146         }
 147
 148         error = ff->upload(dev, effect, old);
 149         if (error)
 150                 return error;
 151
 152         scoped_guard(spinlock_irq, &dev->event_lock) {
 153                 ff->effects[id] = *effect;
 154                 ff->effect_owners[id] = file;
 155         }
 156
 157         return 0;
 158 }
 159 EXPORT_SYMBOL_GPL(input_ff_upload);
 160
 161 /*
 162  * Erases the effect if the requester is also the effect owner. The mutex
 163  * should already be locked before calling this function.
 164  */
 165 static int erase_effect(struct input_dev *dev, int effect_id,
 166                         struct file *file)
 167 {
 168         struct ff_device *ff = dev->ff;
 169         int error;
 170
 171         error = check_effect_access(ff, effect_id, file);
 172         if (error)
 173                 return error;
 174
 175         scoped_guard(spinlock_irq, &dev->event_lock) {
 176                 ff->playback(dev, effect_id, 0);
 177                 ff->effect_owners[effect_id] = NULL;
 178         }
 179
 180         if (ff->erase) {
 181                 error = ff->erase(dev, effect_id);
 182                 if (error) {
 183                         scoped_guard(spinlock_irq, &dev->event_lock)
 184                                 ff->effect_owners[effect_id] = file;
 185
 186                         return error;
 187                 }
 188         }
 189
 190         return 0;
 191 }
 192
 193 /**
 194  * input_ff_erase - erase a force-feedback effect from device
 195  * @dev: input device to erase effect from
 196  * @effect_id: id of the effect to be erased
 197  * @file: purported owner of the request
 198  *
 199  * This function erases a force-feedback effect from specified device.
 200  * The effect will only be erased if it was uploaded through the same
 201  * file handle that is requesting erase.
 202  */
 203 int input_ff_erase(struct input_dev *dev, int effect_id, struct file *file)
 204 {
 205         struct ff_device *ff = dev->ff;
 206
 207         if (!test_bit(EV_FF, dev->evbit))
 208                 return -ENOSYS;
 209
 210         guard(mutex)(&ff->mutex);
 211         return erase_effect(dev, effect_id, file);
 212 }
 213 EXPORT_SYMBOL_GPL(input_ff_erase);
 214
 215 /*
 216  * input_ff_flush - erase all effects owned by a file handle
 217  * @dev: input device to erase effect from
 218  * @file: purported owner of the effects
 219  *
 220  * This function erases all force-feedback effects associated with
 221  * the given owner from specified device. Note that @file may be %NULL,
 222  * in which case all effects will be erased.
 223  */
 224 int input_ff_flush(struct input_dev *dev, struct file *file)
 225 {
 226         struct ff_device *ff = dev->ff;
 227         int i;
 228
 229         dev_dbg(&dev->dev, "flushing now\n");
 230
 231         guard(mutex)(&ff->mutex);
 232
 233         for (i = 0; i < ff->max_effects; i++)
 234                 erase_effect(dev, i, file);
 235
 236         return 0;
 237 }
 238 EXPORT_SYMBOL_GPL(input_ff_flush);
 239
 240 /**
 241  * input_ff_event() - generic handler for force-feedback events
 242  * @dev: input device to send the effect to
 243  * @type: event type (anything but EV_FF is ignored)
 244  * @code: event code
 245  * @value: event value
 246  */
 247 int input_ff_event(struct input_dev *dev, unsigned int type,
 248                    unsigned int code, int value)
 249 {
 250         struct ff_device *ff = dev->ff;
 251
 252         if (type != EV_FF)
 253                 return 0;
 254
 255         switch (code) {
 256         case FF_GAIN:
 257                 if (!test_bit(FF_GAIN, dev->ffbit) || value > 0xffffU)
 258                         break;
 259
 260                 ff->set_gain(dev, value);
 261                 break;
 262
 263         case FF_AUTOCENTER:
 264                 if (!test_bit(FF_AUTOCENTER, dev->ffbit) || value > 0xffffU)
 265                         break;
 266
 267                 ff->set_autocenter(dev, value);
 268                 break;
 269
 270         default:
 271                 if (check_effect_access(ff, code, NULL) == 0)
 272                         ff->playback(dev, code, value);
 273                 break;
 274         }
 275
 276         return 0;
 277 }
 278 EXPORT_SYMBOL_GPL(input_ff_event);
 279
 280 /**
 281  * input_ff_create() - create force-feedback device
 282  * @dev: input device supporting force-feedback
 283  * @max_effects: maximum number of effects supported by the device
 284  *
 285  * This function allocates all necessary memory for a force feedback
 286  * portion of an input device and installs all default handlers.
 287  * @dev->ffbit should be already set up before calling this function.
 288  * Once ff device is created you need to setup its upload, erase,
 289  * playback and other handlers before registering input device
 290  */
 291 int input_ff_create(struct input_dev *dev, unsigned int max_effects)
 292 {
 293         int i;
 294
 295         if (!max_effects) {
 296                 dev_err(&dev->dev, "cannot allocate device without any effects\n");
 297                 return -EINVAL;
 298         }
 299
 300         if (max_effects > FF_MAX_EFFECTS) {
 301                 dev_err(&dev->dev, "cannot allocate more than FF_MAX_EFFECTS effects\n");
 302                 return -EINVAL;
 303         }
 304
 305         struct ff_device *ff __free(kfree) =
 306                 kzalloc(struct_size(ff, effect_owners, max_effects),
 307                         GFP_KERNEL);
 308         if (!ff)
 309                 return -ENOMEM;
 310
 311         ff->effects = kcalloc(max_effects, sizeof(*ff->effects), GFP_KERNEL);
 312         if (!ff->effects)
 313                 return -ENOMEM;
 314
 315         ff->max_effects = max_effects;
 316         mutex_init(&ff->mutex);
 317
 318         dev->flush = input_ff_flush;
 319         dev->event = input_ff_event;
 320         __set_bit(EV_FF, dev->evbit);
 321
 322         /* Copy "true" bits into ff device bitmap */
 323         for_each_set_bit(i, dev->ffbit, FF_CNT)
 324                 __set_bit(i, ff->ffbit);
 325
 326         /* we can emulate RUMBLE with periodic effects */
 327         if (test_bit(FF_PERIODIC, ff->ffbit))
 328                 __set_bit(FF_RUMBLE, dev->ffbit);
 329
 330         dev->ff = no_free_ptr(ff);
 331
 332         return 0;
 333 }
 334 EXPORT_SYMBOL_GPL(input_ff_create);
 335
 336 /**
 337  * input_ff_destroy() - frees force feedback portion of input device
 338  * @dev: input device supporting force feedback
 339  *
 340  * This function is only needed in error path as input core will
 341  * automatically free force feedback structures when device is
 342  * destroyed.
 343  */
 344 void input_ff_destroy(struct input_dev *dev)
 345 {
 346         struct ff_device *ff = dev->ff;
 347
 348         __clear_bit(EV_FF, dev->evbit);
 349         if (ff) {
 350                 if (ff->destroy)
 351                         ff->destroy(ff);
 352                 kfree(ff->private);
 353                 kfree(ff->effects);
 354                 kfree(ff);
 355                 dev->ff = NULL;
 356         }
 357 }
 358 EXPORT_SYMBOL_GPL(input_ff_destroy);