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