xref: /openbmc/linux/sound/core/sound.c (revision 275876e2) 
1 /*
2  *  Advanced Linux Sound Architecture
3  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
4  *
5  *
6  *   This program is free software; you can redistribute it and/or modify
7  *   it under the terms of the GNU General Public License as published by
8  *   the Free Software Foundation; either version 2 of the License, or
9  *   (at your option) any later version.
10  *
11  *   This program is distributed in the hope that it will be useful,
12  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
13  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  *   GNU General Public License for more details.
15  *
16  *   You should have received a copy of the GNU General Public License
17  *   along with this program; if not, write to the Free Software
18  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
19  *
20  */
21 
22 #include <linux/init.h>
23 #include <linux/slab.h>
24 #include <linux/time.h>
25 #include <linux/device.h>
26 #include <linux/module.h>
27 #include <sound/core.h>
28 #include <sound/minors.h>
29 #include <sound/info.h>
30 #include <sound/control.h>
31 #include <sound/initval.h>
32 #include <linux/kmod.h>
33 #include <linux/mutex.h>
34 
35 static int major = CONFIG_SND_MAJOR;
36 int snd_major;
37 EXPORT_SYMBOL(snd_major);
38 
39 static int cards_limit = 1;
40 
41 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
42 MODULE_DESCRIPTION("Advanced Linux Sound Architecture driver for soundcards.");
43 MODULE_LICENSE("GPL");
44 module_param(major, int, 0444);
45 MODULE_PARM_DESC(major, "Major # for sound driver.");
46 module_param(cards_limit, int, 0444);
47 MODULE_PARM_DESC(cards_limit, "Count of auto-loadable soundcards.");
48 MODULE_ALIAS_CHARDEV_MAJOR(CONFIG_SND_MAJOR);
49 
50 /* this one holds the actual max. card number currently available.
51  * as default, it's identical with cards_limit option.  when more
52  * modules are loaded manually, this limit number increases, too.
53  */
54 int snd_ecards_limit;
55 EXPORT_SYMBOL(snd_ecards_limit);
56 
57 static struct snd_minor *snd_minors[SNDRV_OS_MINORS];
58 static DEFINE_MUTEX(sound_mutex);
59 
60 #ifdef CONFIG_MODULES
61 
62 /**
63  * snd_request_card - try to load the card module
64  * @card: the card number
65  *
66  * Tries to load the module "snd-card-X" for the given card number
67  * via request_module.  Returns immediately if already loaded.
68  */
69 void snd_request_card(int card)
70 {
71 	if (snd_card_locked(card))
72 		return;
73 	if (card < 0 || card >= cards_limit)
74 		return;
75 	request_module("snd-card-%i", card);
76 }
77 
78 EXPORT_SYMBOL(snd_request_card);
79 
80 static void snd_request_other(int minor)
81 {
82 	char *str;
83 
84 	switch (minor) {
85 	case SNDRV_MINOR_SEQUENCER:	str = "snd-seq";	break;
86 	case SNDRV_MINOR_TIMER:		str = "snd-timer";	break;
87 	default:			return;
88 	}
89 	request_module(str);
90 }
91 
92 #endif	/* modular kernel */
93 
94 /**
95  * snd_lookup_minor_data - get user data of a registered device
96  * @minor: the minor number
97  * @type: device type (SNDRV_DEVICE_TYPE_XXX)
98  *
99  * Checks that a minor device with the specified type is registered, and returns
100  * its user data pointer.
101  *
102  * This function increments the reference counter of the card instance
103  * if an associated instance with the given minor number and type is found.
104  * The caller must call snd_card_unref() appropriately later.
105  *
106  * Return: The user data pointer if the specified device is found. %NULL
107  * otherwise.
108  */
109 void *snd_lookup_minor_data(unsigned int minor, int type)
110 {
111 	struct snd_minor *mreg;
112 	void *private_data;
113 
114 	if (minor >= ARRAY_SIZE(snd_minors))
115 		return NULL;
116 	mutex_lock(&sound_mutex);
117 	mreg = snd_minors[minor];
118 	if (mreg && mreg->type == type) {
119 		private_data = mreg->private_data;
120 		if (private_data && mreg->card_ptr)
121 			get_device(&mreg->card_ptr->card_dev);
122 	} else
123 		private_data = NULL;
124 	mutex_unlock(&sound_mutex);
125 	return private_data;
126 }
127 
128 EXPORT_SYMBOL(snd_lookup_minor_data);
129 
130 #ifdef CONFIG_MODULES
131 static struct snd_minor *autoload_device(unsigned int minor)
132 {
133 	int dev;
134 	mutex_unlock(&sound_mutex); /* release lock temporarily */
135 	dev = SNDRV_MINOR_DEVICE(minor);
136 	if (dev == SNDRV_MINOR_CONTROL) {
137 		/* /dev/aloadC? */
138 		int card = SNDRV_MINOR_CARD(minor);
139 		if (snd_cards[card] == NULL)
140 			snd_request_card(card);
141 	} else if (dev == SNDRV_MINOR_GLOBAL) {
142 		/* /dev/aloadSEQ */
143 		snd_request_other(minor);
144 	}
145 	mutex_lock(&sound_mutex); /* reacuire lock */
146 	return snd_minors[minor];
147 }
148 #else /* !CONFIG_MODULES */
149 #define autoload_device(minor)	NULL
150 #endif /* CONFIG_MODULES */
151 
152 static int snd_open(struct inode *inode, struct file *file)
153 {
154 	unsigned int minor = iminor(inode);
155 	struct snd_minor *mptr = NULL;
156 	const struct file_operations *new_fops;
157 	int err = 0;
158 
159 	if (minor >= ARRAY_SIZE(snd_minors))
160 		return -ENODEV;
161 	mutex_lock(&sound_mutex);
162 	mptr = snd_minors[minor];
163 	if (mptr == NULL) {
164 		mptr = autoload_device(minor);
165 		if (!mptr) {
166 			mutex_unlock(&sound_mutex);
167 			return -ENODEV;
168 		}
169 	}
170 	new_fops = fops_get(mptr->f_ops);
171 	mutex_unlock(&sound_mutex);
172 	if (!new_fops)
173 		return -ENODEV;
174 	replace_fops(file, new_fops);
175 
176 	if (file->f_op->open)
177 		err = file->f_op->open(inode, file);
178 	return err;
179 }
180 
181 static const struct file_operations snd_fops =
182 {
183 	.owner =	THIS_MODULE,
184 	.open =		snd_open,
185 	.llseek =	noop_llseek,
186 };
187 
188 #ifdef CONFIG_SND_DYNAMIC_MINORS
189 static int snd_find_free_minor(int type)
190 {
191 	int minor;
192 
193 	/* static minors for module auto loading */
194 	if (type == SNDRV_DEVICE_TYPE_SEQUENCER)
195 		return SNDRV_MINOR_SEQUENCER;
196 	if (type == SNDRV_DEVICE_TYPE_TIMER)
197 		return SNDRV_MINOR_TIMER;
198 
199 	for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor) {
200 		/* skip static minors still used for module auto loading */
201 		if (SNDRV_MINOR_DEVICE(minor) == SNDRV_MINOR_CONTROL)
202 			continue;
203 		if (minor == SNDRV_MINOR_SEQUENCER ||
204 		    minor == SNDRV_MINOR_TIMER)
205 			continue;
206 		if (!snd_minors[minor])
207 			return minor;
208 	}
209 	return -EBUSY;
210 }
211 #else
212 static int snd_kernel_minor(int type, struct snd_card *card, int dev)
213 {
214 	int minor;
215 
216 	switch (type) {
217 	case SNDRV_DEVICE_TYPE_SEQUENCER:
218 	case SNDRV_DEVICE_TYPE_TIMER:
219 		minor = type;
220 		break;
221 	case SNDRV_DEVICE_TYPE_CONTROL:
222 		if (snd_BUG_ON(!card))
223 			return -EINVAL;
224 		minor = SNDRV_MINOR(card->number, type);
225 		break;
226 	case SNDRV_DEVICE_TYPE_HWDEP:
227 	case SNDRV_DEVICE_TYPE_RAWMIDI:
228 	case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
229 	case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
230 	case SNDRV_DEVICE_TYPE_COMPRESS:
231 		if (snd_BUG_ON(!card))
232 			return -EINVAL;
233 		minor = SNDRV_MINOR(card->number, type + dev);
234 		break;
235 	default:
236 		return -EINVAL;
237 	}
238 	if (snd_BUG_ON(minor < 0 || minor >= SNDRV_OS_MINORS))
239 		return -EINVAL;
240 	return minor;
241 }
242 #endif
243 
244 /**
245  * snd_register_device_for_dev - Register the ALSA device file for the card
246  * @type: the device type, SNDRV_DEVICE_TYPE_XXX
247  * @card: the card instance
248  * @dev: the device index
249  * @f_ops: the file operations
250  * @private_data: user pointer for f_ops->open()
251  * @name: the device file name
252  * @device: the &struct device to link this new device to
253  *
254  * Registers an ALSA device file for the given card.
255  * The operators have to be set in reg parameter.
256  *
257  * Return: Zero if successful, or a negative error code on failure.
258  */
259 int snd_register_device_for_dev(int type, struct snd_card *card, int dev,
260 				const struct file_operations *f_ops,
261 				void *private_data,
262 				const char *name, struct device *device)
263 {
264 	int minor;
265 	struct snd_minor *preg;
266 
267 	if (snd_BUG_ON(!name))
268 		return -EINVAL;
269 	preg = kmalloc(sizeof *preg, GFP_KERNEL);
270 	if (preg == NULL)
271 		return -ENOMEM;
272 	preg->type = type;
273 	preg->card = card ? card->number : -1;
274 	preg->device = dev;
275 	preg->f_ops = f_ops;
276 	preg->private_data = private_data;
277 	preg->card_ptr = card;
278 	mutex_lock(&sound_mutex);
279 #ifdef CONFIG_SND_DYNAMIC_MINORS
280 	minor = snd_find_free_minor(type);
281 #else
282 	minor = snd_kernel_minor(type, card, dev);
283 	if (minor >= 0 && snd_minors[minor])
284 		minor = -EBUSY;
285 #endif
286 	if (minor < 0) {
287 		mutex_unlock(&sound_mutex);
288 		kfree(preg);
289 		return minor;
290 	}
291 	snd_minors[minor] = preg;
292 	preg->dev = device_create(sound_class, device, MKDEV(major, minor),
293 				  private_data, "%s", name);
294 	if (IS_ERR(preg->dev)) {
295 		snd_minors[minor] = NULL;
296 		mutex_unlock(&sound_mutex);
297 		minor = PTR_ERR(preg->dev);
298 		kfree(preg);
299 		return minor;
300 	}
301 
302 	mutex_unlock(&sound_mutex);
303 	return 0;
304 }
305 
306 EXPORT_SYMBOL(snd_register_device_for_dev);
307 
308 /* find the matching minor record
309  * return the index of snd_minor, or -1 if not found
310  */
311 static int find_snd_minor(int type, struct snd_card *card, int dev)
312 {
313 	int cardnum, minor;
314 	struct snd_minor *mptr;
315 
316 	cardnum = card ? card->number : -1;
317 	for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor)
318 		if ((mptr = snd_minors[minor]) != NULL &&
319 		    mptr->type == type &&
320 		    mptr->card == cardnum &&
321 		    mptr->device == dev)
322 			return minor;
323 	return -1;
324 }
325 
326 /**
327  * snd_unregister_device - unregister the device on the given card
328  * @type: the device type, SNDRV_DEVICE_TYPE_XXX
329  * @card: the card instance
330  * @dev: the device index
331  *
332  * Unregisters the device file already registered via
333  * snd_register_device().
334  *
335  * Return: Zero if successful, or a negative error code on failure.
336  */
337 int snd_unregister_device(int type, struct snd_card *card, int dev)
338 {
339 	int minor;
340 
341 	mutex_lock(&sound_mutex);
342 	minor = find_snd_minor(type, card, dev);
343 	if (minor < 0) {
344 		mutex_unlock(&sound_mutex);
345 		return -EINVAL;
346 	}
347 
348 	device_destroy(sound_class, MKDEV(major, minor));
349 
350 	kfree(snd_minors[minor]);
351 	snd_minors[minor] = NULL;
352 	mutex_unlock(&sound_mutex);
353 	return 0;
354 }
355 
356 EXPORT_SYMBOL(snd_unregister_device);
357 
358 /* get the assigned device to the given type and device number;
359  * the caller needs to release it via put_device() after using it
360  */
361 struct device *snd_get_device(int type, struct snd_card *card, int dev)
362 {
363 	int minor;
364 	struct device *d = NULL;
365 
366 	mutex_lock(&sound_mutex);
367 	minor = find_snd_minor(type, card, dev);
368 	if (minor >= 0) {
369 		d = snd_minors[minor]->dev;
370 		if (d)
371 			get_device(d);
372 	}
373 	mutex_unlock(&sound_mutex);
374 	return d;
375 }
376 EXPORT_SYMBOL(snd_get_device);
377 
378 #ifdef CONFIG_PROC_FS
379 /*
380  *  INFO PART
381  */
382 
383 static struct snd_info_entry *snd_minor_info_entry;
384 
385 static const char *snd_device_type_name(int type)
386 {
387 	switch (type) {
388 	case SNDRV_DEVICE_TYPE_CONTROL:
389 		return "control";
390 	case SNDRV_DEVICE_TYPE_HWDEP:
391 		return "hardware dependent";
392 	case SNDRV_DEVICE_TYPE_RAWMIDI:
393 		return "raw midi";
394 	case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
395 		return "digital audio playback";
396 	case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
397 		return "digital audio capture";
398 	case SNDRV_DEVICE_TYPE_SEQUENCER:
399 		return "sequencer";
400 	case SNDRV_DEVICE_TYPE_TIMER:
401 		return "timer";
402 	default:
403 		return "?";
404 	}
405 }
406 
407 static void snd_minor_info_read(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
408 {
409 	int minor;
410 	struct snd_minor *mptr;
411 
412 	mutex_lock(&sound_mutex);
413 	for (minor = 0; minor < SNDRV_OS_MINORS; ++minor) {
414 		if (!(mptr = snd_minors[minor]))
415 			continue;
416 		if (mptr->card >= 0) {
417 			if (mptr->device >= 0)
418 				snd_iprintf(buffer, "%3i: [%2i-%2i]: %s\n",
419 					    minor, mptr->card, mptr->device,
420 					    snd_device_type_name(mptr->type));
421 			else
422 				snd_iprintf(buffer, "%3i: [%2i]   : %s\n",
423 					    minor, mptr->card,
424 					    snd_device_type_name(mptr->type));
425 		} else
426 			snd_iprintf(buffer, "%3i:        : %s\n", minor,
427 				    snd_device_type_name(mptr->type));
428 	}
429 	mutex_unlock(&sound_mutex);
430 }
431 
432 int __init snd_minor_info_init(void)
433 {
434 	struct snd_info_entry *entry;
435 
436 	entry = snd_info_create_module_entry(THIS_MODULE, "devices", NULL);
437 	if (entry) {
438 		entry->c.text.read = snd_minor_info_read;
439 		if (snd_info_register(entry) < 0) {
440 			snd_info_free_entry(entry);
441 			entry = NULL;
442 		}
443 	}
444 	snd_minor_info_entry = entry;
445 	return 0;
446 }
447 
448 int __exit snd_minor_info_done(void)
449 {
450 	snd_info_free_entry(snd_minor_info_entry);
451 	return 0;
452 }
453 #endif /* CONFIG_PROC_FS */
454 
455 /*
456  *  INIT PART
457  */
458 
459 static int __init alsa_sound_init(void)
460 {
461 	snd_major = major;
462 	snd_ecards_limit = cards_limit;
463 	if (register_chrdev(major, "alsa", &snd_fops)) {
464 		pr_err("ALSA core: unable to register native major device number %d\n", major);
465 		return -EIO;
466 	}
467 	if (snd_info_init() < 0) {
468 		unregister_chrdev(major, "alsa");
469 		return -ENOMEM;
470 	}
471 	snd_info_minor_register();
472 #ifndef MODULE
473 	pr_info("Advanced Linux Sound Architecture Driver Initialized.\n");
474 #endif
475 	return 0;
476 }
477 
478 static void __exit alsa_sound_exit(void)
479 {
480 	snd_info_minor_unregister();
481 	snd_info_done();
482 	unregister_chrdev(major, "alsa");
483 }
484 
485 subsys_initcall(alsa_sound_init);
486 module_exit(alsa_sound_exit);
487