sound/core/sound.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *  Advanced Linux Sound Architecture
0004  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
0005  */
0006
0007 #include <linux/init.h>
0008 #include <linux/slab.h>
0009 #include <linux/time.h>
0010 #include <linux/device.h>
0011 #include <linux/module.h>
0012 #include <linux/debugfs.h>
0013 #include <sound/core.h>
0014 #include <sound/minors.h>
0015 #include <sound/info.h>
0016 #include <sound/control.h>
0017 #include <sound/initval.h>
0018 #include <linux/kmod.h>
0019 #include <linux/mutex.h>
0020
0021 static int major = CONFIG_SND_MAJOR;
0022 int snd_major;
0023 EXPORT_SYMBOL(snd_major);
0024
0025 static int cards_limit = 1;
0026
0027 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
0028 MODULE_DESCRIPTION("Advanced Linux Sound Architecture driver for soundcards.");
0029 MODULE_LICENSE("GPL");
0030 module_param(major, int, 0444);
0031 MODULE_PARM_DESC(major, "Major # for sound driver.");
0032 module_param(cards_limit, int, 0444);
0033 MODULE_PARM_DESC(cards_limit, "Count of auto-loadable soundcards.");
0034 MODULE_ALIAS_CHARDEV_MAJOR(CONFIG_SND_MAJOR);
0035
0036 /* this one holds the actual max. card number currently available.
0037  * as default, it's identical with cards_limit option.  when more
0038  * modules are loaded manually, this limit number increases, too.
0039  */
0040 int snd_ecards_limit;
0041 EXPORT_SYMBOL(snd_ecards_limit);
0042
0043 #ifdef CONFIG_SND_DEBUG
0044 struct dentry *sound_debugfs_root;
0045 EXPORT_SYMBOL_GPL(sound_debugfs_root);
0046 #endif
0047
0048 static struct snd_minor *snd_minors[SNDRV_OS_MINORS];
0049 static DEFINE_MUTEX(sound_mutex);
0050
0051 #ifdef CONFIG_MODULES
0052
0053 /**
0054  * snd_request_card - try to load the card module
0055  * @card: the card number
0056  *
0057  * Tries to load the module "snd-card-X" for the given card number
0058  * via request_module.  Returns immediately if already loaded.
0059  */
0060 void snd_request_card(int card)
0061 {
0062     if (snd_card_locked(card))
0063         return;
0064     if (card < 0 || card >= cards_limit)
0065         return;
0066     request_module("snd-card-%i", card);
0067 }
0068 EXPORT_SYMBOL(snd_request_card);
0069
0070 static void snd_request_other(int minor)
0071 {
0072     char *str;
0073
0074     switch (minor) {
0075     case SNDRV_MINOR_SEQUENCER: str = "snd-seq";    break;
0076     case SNDRV_MINOR_TIMER:     str = "snd-timer";  break;
0077     default:            return;
0078     }
0079     request_module(str);
0080 }
0081
0082 #endif  /* modular kernel */
0083
0084 /**
0085  * snd_lookup_minor_data - get user data of a registered device
0086  * @minor: the minor number
0087  * @type: device type (SNDRV_DEVICE_TYPE_XXX)
0088  *
0089  * Checks that a minor device with the specified type is registered, and returns
0090  * its user data pointer.
0091  *
0092  * This function increments the reference counter of the card instance
0093  * if an associated instance with the given minor number and type is found.
0094  * The caller must call snd_card_unref() appropriately later.
0095  *
0096  * Return: The user data pointer if the specified device is found. %NULL
0097  * otherwise.
0098  */
0099 void *snd_lookup_minor_data(unsigned int minor, int type)
0100 {
0101     struct snd_minor *mreg;
0102     void *private_data;
0103
0104     if (minor >= ARRAY_SIZE(snd_minors))
0105         return NULL;
0106     mutex_lock(&sound_mutex);
0107     mreg = snd_minors[minor];
0108     if (mreg && mreg->type == type) {
0109         private_data = mreg->private_data;
0110         if (private_data && mreg->card_ptr)
0111             get_device(&mreg->card_ptr->card_dev);
0112     } else
0113         private_data = NULL;
0114     mutex_unlock(&sound_mutex);
0115     return private_data;
0116 }
0117 EXPORT_SYMBOL(snd_lookup_minor_data);
0118
0119 #ifdef CONFIG_MODULES
0120 static struct snd_minor *autoload_device(unsigned int minor)
0121 {
0122     int dev;
0123     mutex_unlock(&sound_mutex); /* release lock temporarily */
0124     dev = SNDRV_MINOR_DEVICE(minor);
0125     if (dev == SNDRV_MINOR_CONTROL) {
0126         /* /dev/aloadC? */
0127         int card = SNDRV_MINOR_CARD(minor);
0128         struct snd_card *ref = snd_card_ref(card);
0129         if (!ref)
0130             snd_request_card(card);
0131         else
0132             snd_card_unref(ref);
0133     } else if (dev == SNDRV_MINOR_GLOBAL) {
0134         /* /dev/aloadSEQ */
0135         snd_request_other(minor);
0136     }
0137     mutex_lock(&sound_mutex); /* reacuire lock */
0138     return snd_minors[minor];
0139 }
0140 #else /* !CONFIG_MODULES */
0141 #define autoload_device(minor)  NULL
0142 #endif /* CONFIG_MODULES */
0143
0144 static int snd_open(struct inode *inode, struct file *file)
0145 {
0146     unsigned int minor = iminor(inode);
0147     struct snd_minor *mptr = NULL;
0148     const struct file_operations *new_fops;
0149     int err = 0;
0150
0151     if (minor >= ARRAY_SIZE(snd_minors))
0152         return -ENODEV;
0153     mutex_lock(&sound_mutex);
0154     mptr = snd_minors[minor];
0155     if (mptr == NULL) {
0156         mptr = autoload_device(minor);
0157         if (!mptr) {
0158             mutex_unlock(&sound_mutex);
0159             return -ENODEV;
0160         }
0161     }
0162     new_fops = fops_get(mptr->f_ops);
0163     mutex_unlock(&sound_mutex);
0164     if (!new_fops)
0165         return -ENODEV;
0166     replace_fops(file, new_fops);
0167
0168     if (file->f_op->open)
0169         err = file->f_op->open(inode, file);
0170     return err;
0171 }
0172
0173 static const struct file_operations snd_fops =
0174 {
0175     .owner =    THIS_MODULE,
0176     .open =     snd_open,
0177     .llseek =   noop_llseek,
0178 };
0179
0180 #ifdef CONFIG_SND_DYNAMIC_MINORS
0181 static int snd_find_free_minor(int type, struct snd_card *card, int dev)
0182 {
0183     int minor;
0184
0185     /* static minors for module auto loading */
0186     if (type == SNDRV_DEVICE_TYPE_SEQUENCER)
0187         return SNDRV_MINOR_SEQUENCER;
0188     if (type == SNDRV_DEVICE_TYPE_TIMER)
0189         return SNDRV_MINOR_TIMER;
0190
0191     for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor) {
0192         /* skip static minors still used for module auto loading */
0193         if (SNDRV_MINOR_DEVICE(minor) == SNDRV_MINOR_CONTROL)
0194             continue;
0195         if (minor == SNDRV_MINOR_SEQUENCER ||
0196             minor == SNDRV_MINOR_TIMER)
0197             continue;
0198         if (!snd_minors[minor])
0199             return minor;
0200     }
0201     return -EBUSY;
0202 }
0203 #else
0204 static int snd_find_free_minor(int type, struct snd_card *card, int dev)
0205 {
0206     int minor;
0207
0208     switch (type) {
0209     case SNDRV_DEVICE_TYPE_SEQUENCER:
0210     case SNDRV_DEVICE_TYPE_TIMER:
0211         minor = type;
0212         break;
0213     case SNDRV_DEVICE_TYPE_CONTROL:
0214         if (snd_BUG_ON(!card))
0215             return -EINVAL;
0216         minor = SNDRV_MINOR(card->number, type);
0217         break;
0218     case SNDRV_DEVICE_TYPE_HWDEP:
0219     case SNDRV_DEVICE_TYPE_RAWMIDI:
0220     case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
0221     case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
0222     case SNDRV_DEVICE_TYPE_COMPRESS:
0223         if (snd_BUG_ON(!card))
0224             return -EINVAL;
0225         minor = SNDRV_MINOR(card->number, type + dev);
0226         break;
0227     default:
0228         return -EINVAL;
0229     }
0230     if (snd_BUG_ON(minor < 0 || minor >= SNDRV_OS_MINORS))
0231         return -EINVAL;
0232     if (snd_minors[minor])
0233         return -EBUSY;
0234     return minor;
0235 }
0236 #endif
0237
0238 /**
0239  * snd_register_device - Register the ALSA device file for the card
0240  * @type: the device type, SNDRV_DEVICE_TYPE_XXX
0241  * @card: the card instance
0242  * @dev: the device index
0243  * @f_ops: the file operations
0244  * @private_data: user pointer for f_ops->open()
0245  * @device: the device to register
0246  *
0247  * Registers an ALSA device file for the given card.
0248  * The operators have to be set in reg parameter.
0249  *
0250  * Return: Zero if successful, or a negative error code on failure.
0251  */
0252 int snd_register_device(int type, struct snd_card *card, int dev,
0253             const struct file_operations *f_ops,
0254             void *private_data, struct device *device)
0255 {
0256     int minor;
0257     int err = 0;
0258     struct snd_minor *preg;
0259
0260     if (snd_BUG_ON(!device))
0261         return -EINVAL;
0262
0263     preg = kmalloc(sizeof *preg, GFP_KERNEL);
0264     if (preg == NULL)
0265         return -ENOMEM;
0266     preg->type = type;
0267     preg->card = card ? card->number : -1;
0268     preg->device = dev;
0269     preg->f_ops = f_ops;
0270     preg->private_data = private_data;
0271     preg->card_ptr = card;
0272     mutex_lock(&sound_mutex);
0273     minor = snd_find_free_minor(type, card, dev);
0274     if (minor < 0) {
0275         err = minor;
0276         goto error;
0277     }
0278
0279     preg->dev = device;
0280     device->devt = MKDEV(major, minor);
0281     err = device_add(device);
0282     if (err < 0)
0283         goto error;
0284
0285     snd_minors[minor] = preg;
0286  error:
0287     mutex_unlock(&sound_mutex);
0288     if (err < 0)
0289         kfree(preg);
0290     return err;
0291 }
0292 EXPORT_SYMBOL(snd_register_device);
0293
0294 /**
0295  * snd_unregister_device - unregister the device on the given card
0296  * @dev: the device instance
0297  *
0298  * Unregisters the device file already registered via
0299  * snd_register_device().
0300  *
0301  * Return: Zero if successful, or a negative error code on failure.
0302  */
0303 int snd_unregister_device(struct device *dev)
0304 {
0305     int minor;
0306     struct snd_minor *preg;
0307
0308     mutex_lock(&sound_mutex);
0309     for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor) {
0310         preg = snd_minors[minor];
0311         if (preg && preg->dev == dev) {
0312             snd_minors[minor] = NULL;
0313             device_del(dev);
0314             kfree(preg);
0315             break;
0316         }
0317     }
0318     mutex_unlock(&sound_mutex);
0319     if (minor >= ARRAY_SIZE(snd_minors))
0320         return -ENOENT;
0321     return 0;
0322 }
0323 EXPORT_SYMBOL(snd_unregister_device);
0324
0325 #ifdef CONFIG_SND_PROC_FS
0326 /*
0327  *  INFO PART
0328  */
0329 static const char *snd_device_type_name(int type)
0330 {
0331     switch (type) {
0332     case SNDRV_DEVICE_TYPE_CONTROL:
0333         return "control";
0334     case SNDRV_DEVICE_TYPE_HWDEP:
0335         return "hardware dependent";
0336     case SNDRV_DEVICE_TYPE_RAWMIDI:
0337         return "raw midi";
0338     case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
0339         return "digital audio playback";
0340     case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
0341         return "digital audio capture";
0342     case SNDRV_DEVICE_TYPE_SEQUENCER:
0343         return "sequencer";
0344     case SNDRV_DEVICE_TYPE_TIMER:
0345         return "timer";
0346     case SNDRV_DEVICE_TYPE_COMPRESS:
0347         return "compress";
0348     default:
0349         return "?";
0350     }
0351 }
0352
0353 static void snd_minor_info_read(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
0354 {
0355     int minor;
0356     struct snd_minor *mptr;
0357
0358     mutex_lock(&sound_mutex);
0359     for (minor = 0; minor < SNDRV_OS_MINORS; ++minor) {
0360         mptr = snd_minors[minor];
0361         if (!mptr)
0362             continue;
0363         if (mptr->card >= 0) {
0364             if (mptr->device >= 0)
0365                 snd_iprintf(buffer, "%3i: [%2i-%2i]: %s\n",
0366                         minor, mptr->card, mptr->device,
0367                         snd_device_type_name(mptr->type));
0368             else
0369                 snd_iprintf(buffer, "%3i: [%2i]   : %s\n",
0370                         minor, mptr->card,
0371                         snd_device_type_name(mptr->type));
0372         } else
0373             snd_iprintf(buffer, "%3i:        : %s\n", minor,
0374                     snd_device_type_name(mptr->type));
0375     }
0376     mutex_unlock(&sound_mutex);
0377 }
0378
0379 int __init snd_minor_info_init(void)
0380 {
0381     struct snd_info_entry *entry;
0382
0383     entry = snd_info_create_module_entry(THIS_MODULE, "devices", NULL);
0384     if (!entry)
0385         return -ENOMEM;
0386     entry->c.text.read = snd_minor_info_read;
0387     return snd_info_register(entry); /* freed in error path */
0388 }
0389 #endif /* CONFIG_SND_PROC_FS */
0390
0391 /*
0392  *  INIT PART
0393  */
0394
0395 static int __init alsa_sound_init(void)
0396 {
0397     snd_major = major;
0398     snd_ecards_limit = cards_limit;
0399     if (register_chrdev(major, "alsa", &snd_fops)) {
0400         pr_err("ALSA core: unable to register native major device number %d\n", major);
0401         return -EIO;
0402     }
0403     if (snd_info_init() < 0) {
0404         unregister_chrdev(major, "alsa");
0405         return -ENOMEM;
0406     }
0407
0408 #ifdef CONFIG_SND_DEBUG
0409     sound_debugfs_root = debugfs_create_dir("sound", NULL);
0410 #endif
0411 #ifndef MODULE
0412     pr_info("Advanced Linux Sound Architecture Driver Initialized.\n");
0413 #endif
0414     return 0;
0415 }
0416
0417 static void __exit alsa_sound_exit(void)
0418 {
0419 #ifdef CONFIG_SND_DEBUG
0420     debugfs_remove(sound_debugfs_root);
0421 #endif
0422     snd_info_done();
0423     unregister_chrdev(major, "alsa");
0424 }
0425
0426 subsys_initcall(alsa_sound_init);
0427 module_exit(alsa_sound_exit);