sound/core/sound.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Advanced Linux Sound Architecture
   4  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
   5  */
   6
   7 #include <linux/init.h>
   8 #include <linux/slab.h>
   9 #include <linux/time.h>
  10 #include <linux/device.h>
  11 #include <linux/module.h>
  12 #include <linux/debugfs.h>
  13 #include <sound/core.h>
  14 #include <sound/minors.h>
  15 #include <sound/info.h>
  16 #include <sound/control.h>
  17 #include <sound/initval.h>
  18 #include <linux/kmod.h>
  19 #include <linux/mutex.h>
  20
  21 static int major = CONFIG_SND_MAJOR;
  22 int snd_major;
  23 EXPORT_SYMBOL(snd_major);
  24
  25 static int cards_limit = 1;
  26
  27 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
  28 MODULE_DESCRIPTION("Advanced Linux Sound Architecture driver for soundcards.");
  29 MODULE_LICENSE("GPL");
  30 module_param(major, int, 0444);
  31 MODULE_PARM_DESC(major, "Major # for sound driver.");
  32 module_param(cards_limit, int, 0444);
  33 MODULE_PARM_DESC(cards_limit, "Count of auto-loadable soundcards.");
  34 MODULE_ALIAS_CHARDEV_MAJOR(CONFIG_SND_MAJOR);
  35
  36 /* this one holds the actual max. card number currently available.
  37  * as default, it's identical with cards_limit option.  when more
  38  * modules are loaded manually, this limit number increases, too.
  39  */
  40 int snd_ecards_limit;
  41 EXPORT_SYMBOL(snd_ecards_limit);
  42
  43 #ifdef CONFIG_SND_DEBUG
  44 struct dentry *sound_debugfs_root;
  45 EXPORT_SYMBOL_GPL(sound_debugfs_root);
  46 #endif
  47
  48 static struct snd_minor *snd_minors[SNDRV_OS_MINORS];
  49 static DEFINE_MUTEX(sound_mutex);
  50
  51 #ifdef CONFIG_MODULES
  52
  53 /**
  54  * snd_request_card - try to load the card module
  55  * @card: the card number
  56  *
  57  * Tries to load the module "snd-card-X" for the given card number
  58  * via request_module.  Returns immediately if already loaded.
  59  */
  60 void snd_request_card(int card)
  61 {
  62         if (snd_card_locked(card))
  63                 return;
  64         if (card < 0 || card >= cards_limit)
  65                 return;
  66         request_module("snd-card-%i", card);
  67 }
  68 EXPORT_SYMBOL(snd_request_card);
  69
  70 static void snd_request_other(int minor)
  71 {
  72         char *str;
  73
  74         switch (minor) {
  75         case SNDRV_MINOR_SEQUENCER:     str = "snd-seq";        break;
  76         case SNDRV_MINOR_TIMER:         str = "snd-timer";      break;
  77         default:                        return;
  78         }
  79         request_module(str);
  80 }
  81
  82 #endif  /* modular kernel */
  83
  84 /**
  85  * snd_lookup_minor_data - get user data of a registered device
  86  * @minor: the minor number
  87  * @type: device type (SNDRV_DEVICE_TYPE_XXX)
  88  *
  89  * Checks that a minor device with the specified type is registered, and returns
  90  * its user data pointer.
  91  *
  92  * This function increments the reference counter of the card instance
  93  * if an associated instance with the given minor number and type is found.
  94  * The caller must call snd_card_unref() appropriately later.
  95  *
  96  * Return: The user data pointer if the specified device is found. %NULL
  97  * otherwise.
  98  */
  99 void *snd_lookup_minor_data(unsigned int minor, int type)
 100 {
 101         struct snd_minor *mreg;
 102         void *private_data;
 103
 104         if (minor >= ARRAY_SIZE(snd_minors))
 105                 return NULL;
 106         guard(mutex)(&sound_mutex);
 107         mreg = snd_minors[minor];
 108         if (mreg && mreg->type == type) {
 109                 private_data = mreg->private_data;
 110                 if (private_data && mreg->card_ptr)
 111                         get_device(&mreg->card_ptr->card_dev);
 112         } else
 113                 private_data = NULL;
 114         return private_data;
 115 }
 116 EXPORT_SYMBOL(snd_lookup_minor_data);
 117
 118 #ifdef CONFIG_MODULES
 119 static struct snd_minor *autoload_device(unsigned int minor)
 120 {
 121         int dev;
 122         mutex_unlock(&sound_mutex); /* release lock temporarily */
 123         dev = SNDRV_MINOR_DEVICE(minor);
 124         if (dev == SNDRV_MINOR_CONTROL) {
 125                 /* /dev/aloadC? */
 126                 int card = SNDRV_MINOR_CARD(minor);
 127                 struct snd_card *ref = snd_card_ref(card);
 128                 if (!ref)
 129                         snd_request_card(card);
 130                 else
 131                         snd_card_unref(ref);
 132         } else if (dev == SNDRV_MINOR_GLOBAL) {
 133                 /* /dev/aloadSEQ */
 134                 snd_request_other(minor);
 135         }
 136         mutex_lock(&sound_mutex); /* reacquire lock */
 137         return snd_minors[minor];
 138 }
 139 #else /* !CONFIG_MODULES */
 140 #define autoload_device(minor)  NULL
 141 #endif /* CONFIG_MODULES */
 142
 143 static int snd_open(struct inode *inode, struct file *file)
 144 {
 145         unsigned int minor = iminor(inode);
 146         struct snd_minor *mptr = NULL;
 147         const struct file_operations *new_fops;
 148         int err = 0;
 149
 150         if (minor >= ARRAY_SIZE(snd_minors))
 151                 return -ENODEV;
 152         scoped_guard(mutex, &sound_mutex) {
 153                 mptr = snd_minors[minor];
 154                 if (mptr == NULL) {
 155                         mptr = autoload_device(minor);
 156                         if (!mptr)
 157                                 return -ENODEV;
 158                 }
 159                 new_fops = fops_get(mptr->f_ops);
 160         }
 161         if (!new_fops)
 162                 return -ENODEV;
 163         replace_fops(file, new_fops);
 164
 165         if (file->f_op->open)
 166                 err = file->f_op->open(inode, file);
 167         return err;
 168 }
 169
 170 static const struct file_operations snd_fops =
 171 {
 172         .owner =        THIS_MODULE,
 173         .open =         snd_open,
 174         .llseek =       noop_llseek,
 175 };
 176
 177 #ifdef CONFIG_SND_DYNAMIC_MINORS
 178 static int snd_find_free_minor(int type, struct snd_card *card, int dev)
 179 {
 180         int minor;
 181
 182         /* static minors for module auto loading */
 183         if (type == SNDRV_DEVICE_TYPE_SEQUENCER)
 184                 return SNDRV_MINOR_SEQUENCER;
 185         if (type == SNDRV_DEVICE_TYPE_TIMER)
 186                 return SNDRV_MINOR_TIMER;
 187
 188         for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor) {
 189                 /* skip static minors still used for module auto loading */
 190                 if (SNDRV_MINOR_DEVICE(minor) == SNDRV_MINOR_CONTROL)
 191                         continue;
 192                 if (minor == SNDRV_MINOR_SEQUENCER ||
 193                     minor == SNDRV_MINOR_TIMER)
 194                         continue;
 195                 if (!snd_minors[minor])
 196                         return minor;
 197         }
 198         return -EBUSY;
 199 }
 200 #else
 201 static int snd_find_free_minor(int type, struct snd_card *card, int dev)
 202 {
 203         int minor;
 204
 205         switch (type) {
 206         case SNDRV_DEVICE_TYPE_SEQUENCER:
 207         case SNDRV_DEVICE_TYPE_TIMER:
 208                 minor = type;
 209                 break;
 210         case SNDRV_DEVICE_TYPE_CONTROL:
 211                 if (snd_BUG_ON(!card))
 212                         return -EINVAL;
 213                 minor = SNDRV_MINOR(card->number, type);
 214                 break;
 215         case SNDRV_DEVICE_TYPE_HWDEP:
 216         case SNDRV_DEVICE_TYPE_RAWMIDI:
 217         case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
 218         case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
 219         case SNDRV_DEVICE_TYPE_COMPRESS:
 220                 if (snd_BUG_ON(!card))
 221                         return -EINVAL;
 222                 minor = SNDRV_MINOR(card->number, type + dev);
 223                 break;
 224         default:
 225                 return -EINVAL;
 226         }
 227         if (snd_BUG_ON(minor < 0 || minor >= SNDRV_OS_MINORS))
 228                 return -EINVAL;
 229         if (snd_minors[minor])
 230                 return -EBUSY;
 231         return minor;
 232 }
 233 #endif
 234
 235 /**
 236  * snd_register_device - Register the ALSA device file for the card
 237  * @type: the device type, SNDRV_DEVICE_TYPE_XXX
 238  * @card: the card instance
 239  * @dev: the device index
 240  * @f_ops: the file operations
 241  * @private_data: user pointer for f_ops->open()
 242  * @device: the device to register
 243  *
 244  * Registers an ALSA device file for the given card.
 245  * The operators have to be set in reg parameter.
 246  *
 247  * Return: Zero if successful, or a negative error code on failure.
 248  */
 249 int snd_register_device(int type, struct snd_card *card, int dev,
 250                         const struct file_operations *f_ops,
 251                         void *private_data, struct device *device)
 252 {
 253         int minor;
 254         int err = 0;
 255         struct snd_minor *preg;
 256
 257         if (snd_BUG_ON(!device))
 258                 return -EINVAL;
 259
 260         preg = kmalloc(sizeof *preg, GFP_KERNEL);
 261         if (preg == NULL)
 262                 return -ENOMEM;
 263         preg->type = type;
 264         preg->card = card ? card->number : -1;
 265         preg->device = dev;
 266         preg->f_ops = f_ops;
 267         preg->private_data = private_data;
 268         preg->card_ptr = card;
 269         guard(mutex)(&sound_mutex);
 270         minor = snd_find_free_minor(type, card, dev);
 271         if (minor < 0) {
 272                 err = minor;
 273                 goto error;
 274         }
 275
 276         preg->dev = device;
 277         device->devt = MKDEV(major, minor);
 278         err = device_add(device);
 279         if (err < 0)
 280                 goto error;
 281
 282         snd_minors[minor] = preg;
 283  error:
 284         if (err < 0)
 285                 kfree(preg);
 286         return err;
 287 }
 288 EXPORT_SYMBOL(snd_register_device);
 289
 290 /**
 291  * snd_unregister_device - unregister the device on the given card
 292  * @dev: the device instance
 293  *
 294  * Unregisters the device file already registered via
 295  * snd_register_device().
 296  *
 297  * Return: Zero if successful, or a negative error code on failure.
 298  */
 299 int snd_unregister_device(struct device *dev)
 300 {
 301         int minor;
 302         struct snd_minor *preg;
 303
 304         guard(mutex)(&sound_mutex);
 305         for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor) {
 306                 preg = snd_minors[minor];
 307                 if (preg && preg->dev == dev) {
 308                         snd_minors[minor] = NULL;
 309                         device_del(dev);
 310                         kfree(preg);
 311                         break;
 312                 }
 313         }
 314         if (minor >= ARRAY_SIZE(snd_minors))
 315                 return -ENOENT;
 316         return 0;
 317 }
 318 EXPORT_SYMBOL(snd_unregister_device);
 319
 320 #ifdef CONFIG_SND_PROC_FS
 321 /*
 322  *  INFO PART
 323  */
 324 static const char *snd_device_type_name(int type)
 325 {
 326         switch (type) {
 327         case SNDRV_DEVICE_TYPE_CONTROL:
 328                 return "control";
 329         case SNDRV_DEVICE_TYPE_HWDEP:
 330                 return "hardware dependent";
 331         case SNDRV_DEVICE_TYPE_RAWMIDI:
 332                 return "raw midi";
 333         case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
 334                 return "digital audio playback";
 335         case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
 336                 return "digital audio capture";
 337         case SNDRV_DEVICE_TYPE_SEQUENCER:
 338                 return "sequencer";
 339         case SNDRV_DEVICE_TYPE_TIMER:
 340                 return "timer";
 341         case SNDRV_DEVICE_TYPE_COMPRESS:
 342                 return "compress";
 343         default:
 344                 return "?";
 345         }
 346 }
 347
 348 static void snd_minor_info_read(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
 349 {
 350         int minor;
 351         struct snd_minor *mptr;
 352
 353         guard(mutex)(&sound_mutex);
 354         for (minor = 0; minor < SNDRV_OS_MINORS; ++minor) {
 355                 mptr = snd_minors[minor];
 356                 if (!mptr)
 357                         continue;
 358                 if (mptr->card >= 0) {
 359                         if (mptr->device >= 0)
 360                                 snd_iprintf(buffer, "%3i: [%2i-%2i]: %s\n",
 361                                             minor, mptr->card, mptr->device,
 362                                             snd_device_type_name(mptr->type));
 363                         else
 364                                 snd_iprintf(buffer, "%3i: [%2i]   : %s\n",
 365                                             minor, mptr->card,
 366                                             snd_device_type_name(mptr->type));
 367                 } else
 368                         snd_iprintf(buffer, "%3i:        : %s\n", minor,
 369                                     snd_device_type_name(mptr->type));
 370         }
 371 }
 372
 373 int __init snd_minor_info_init(void)
 374 {
 375         struct snd_info_entry *entry;
 376
 377         entry = snd_info_create_module_entry(THIS_MODULE, "devices", NULL);
 378         if (!entry)
 379                 return -ENOMEM;
 380         entry->c.text.read = snd_minor_info_read;
 381         return snd_info_register(entry); /* freed in error path */
 382 }
 383 #endif /* CONFIG_SND_PROC_FS */
 384
 385 /*
 386  *  INIT PART
 387  */
 388
 389 static int __init alsa_sound_init(void)
 390 {
 391         snd_major = major;
 392         snd_ecards_limit = cards_limit;
 393         if (register_chrdev(major, "alsa", &snd_fops)) {
 394                 pr_err("ALSA core: unable to register native major device number %d\n", major);
 395                 return -EIO;
 396         }
 397         if (snd_info_init() < 0) {
 398                 unregister_chrdev(major, "alsa");
 399                 return -ENOMEM;
 400         }
 401
 402 #ifdef CONFIG_SND_DEBUG
 403         sound_debugfs_root = debugfs_create_dir("sound", NULL);
 404 #endif
 405 #ifndef MODULE
 406         pr_info("Advanced Linux Sound Architecture Driver Initialized.\n");
 407 #endif
 408         return 0;
 409 }
 410
 411 static void __exit alsa_sound_exit(void)
 412 {
 413 #ifdef CONFIG_SND_DEBUG
 414         debugfs_remove(sound_debugfs_root);
 415 #endif
 416         snd_info_done();
 417         unregister_chrdev(major, "alsa");
 418 }
 419
 420 subsys_initcall(alsa_sound_init);
 421 module_exit(alsa_sound_exit);