xref: /linux/sound/core/sound.c (revision e6a901a00822659181c93c86d8bbc2a17779fddc) 
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); /* reacuire 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);
422