summaryrefslogtreecommitdiffstats
path: root/sound/core/sound.c
blob: b75f78f2c4b8e222e46297589c5bf6ca8055d9d4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Advanced Linux Sound Architecture
 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
 */

#include <linux/init.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/device.h>
#include <linux/module.h>
#include <sound/core.h>
#include <sound/minors.h>
#include <sound/info.h>
#include <sound/control.h>
#include <sound/initval.h>
#include <linux/kmod.h>
#include <linux/mutex.h>

static int major = CONFIG_SND_MAJOR;
int snd_major;
EXPORT_SYMBOL(snd_major);

static int cards_limit = 1;

MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
MODULE_DESCRIPTION("Advanced Linux Sound Architecture driver for soundcards.");
MODULE_LICENSE("GPL");
module_param(major, int, 0444);
MODULE_PARM_DESC(major, "Major # for sound driver.");
module_param(cards_limit, int, 0444);
MODULE_PARM_DESC(cards_limit, "Count of auto-loadable soundcards.");
MODULE_ALIAS_CHARDEV_MAJOR(CONFIG_SND_MAJOR);

/* this one holds the actual max. card number currently available.
 * as default, it's identical with cards_limit option.  when more
 * modules are loaded manually, this limit number increases, too.
 */
int snd_ecards_limit;
EXPORT_SYMBOL(snd_ecards_limit);

static struct snd_minor *snd_minors[SNDRV_OS_MINORS];
static DEFINE_MUTEX(sound_mutex);

#ifdef CONFIG_MODULES

/**
 * snd_request_card - try to load the card module
 * @card: the card number
 *
 * Tries to load the module "snd-card-X" for the given card number
 * via request_module.  Returns immediately if already loaded.
 */
void snd_request_card(int card)
{
	if (snd_card_locked(card))
		return;
	if (card < 0 || card >= cards_limit)
		return;
	request_module("snd-card-%i", card);
}
EXPORT_SYMBOL(snd_request_card);

static void snd_request_other(int minor)
{
	char *str;

	switch (minor) {
	case SNDRV_MINOR_SEQUENCER:	str = "snd-seq";	break;
	case SNDRV_MINOR_TIMER:		str = "snd-timer";	break;
	default:			return;
	}
	request_module(str);
}

#endif	/* modular kernel */

/**
 * snd_lookup_minor_data - get user data of a registered device
 * @minor: the minor number
 * @type: device type (SNDRV_DEVICE_TYPE_XXX)
 *
 * Checks that a minor device with the specified type is registered, and returns
 * its user data pointer.
 *
 * This function increments the reference counter of the card instance
 * if an associated instance with the given minor number and type is found.
 * The caller must call snd_card_unref() appropriately later.
 *
 * Return: The user data pointer if the specified device is found. %NULL
 * otherwise.
 */
void *snd_lookup_minor_data(unsigned int minor, int type)
{
	struct snd_minor *mreg;
	void *private_data;

	if (minor >= ARRAY_SIZE(snd_minors))
		return NULL;
	mutex_lock(&sound_mutex);
	mreg = snd_minors[minor];
	if (mreg && mreg->type == type) {
		private_data = mreg->private_data;
		if (private_data && mreg->card_ptr)
			get_device(&mreg->card_ptr->card_dev);
	} else
		private_data = NULL;
	mutex_unlock(&sound_mutex);
	return private_data;
}
EXPORT_SYMBOL(snd_lookup_minor_data);

#ifdef CONFIG_MODULES
static struct snd_minor *autoload_device(unsigned int minor)
{
	int dev;
	mutex_unlock(&sound_mutex); /* release lock temporarily */
	dev = SNDRV_MINOR_DEVICE(minor);
	if (dev == SNDRV_MINOR_CONTROL) {
		/* /dev/aloadC? */
		int card = SNDRV_MINOR_CARD(minor);
		struct snd_card *ref = snd_card_ref(card);
		if (!ref)
			snd_request_card(card);
		else
			snd_card_unref(ref);
	} else if (dev == SNDRV_MINOR_GLOBAL) {
		/* /dev/aloadSEQ */
		snd_request_other(minor);
	}
	mutex_lock(&sound_mutex); /* reacuire lock */
	return snd_minors[minor];
}
#else /* !CONFIG_MODULES */
#define autoload_device(minor)	NULL
#endif /* CONFIG_MODULES */

static int snd_open(struct inode *inode, struct file *file)
{
	unsigned int minor = iminor(inode);
	struct snd_minor *mptr = NULL;
	const struct file_operations *new_fops;
	int err = 0;

	if (minor >= ARRAY_SIZE(snd_minors))
		return -ENODEV;
	mutex_lock(&sound_mutex);
	mptr = snd_minors[minor];
	if (mptr == NULL) {
		mptr = autoload_device(minor);
		if (!mptr) {
			mutex_unlock(&sound_mutex);
			return -ENODEV;
		}
	}
	new_fops = fops_get(mptr->f_ops);
	mutex_unlock(&sound_mutex);
	if (!new_fops)
		return -ENODEV;
	replace_fops(file, new_fops);

	if (file->f_op->open)
		err = file->f_op->open(inode, file);
	return err;
}

static const struct file_operations snd_fops =
{
	.owner =	THIS_MODULE,
	.open =		snd_open,
	.llseek =	noop_llseek,
};

#ifdef CONFIG_SND_DYNAMIC_MINORS
static int snd_find_free_minor(int type, struct snd_card *card, int dev)
{
	int minor;

	/* static minors for module auto loading */
	if (type == SNDRV_DEVICE_TYPE_SEQUENCER)
		return SNDRV_MINOR_SEQUENCER;
	if (type == SNDRV_DEVICE_TYPE_TIMER)
		return SNDRV_MINOR_TIMER;

	for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor) {
		/* skip static minors still used for module auto loading */
		if (SNDRV_MINOR_DEVICE(minor) == SNDRV_MINOR_CONTROL)
			continue;
		if (minor == SNDRV_MINOR_SEQUENCER ||
		    minor == SNDRV_MINOR_TIMER)
			continue;
		if (!snd_minors[minor])
			return minor;
	}
	return -EBUSY;
}
#else
static int snd_find_free_minor(int type, struct snd_card *card, int dev)
{
	int minor;

	switch (type) {
	case SNDRV_DEVICE_TYPE_SEQUENCER:
	case SNDRV_DEVICE_TYPE_TIMER:
		minor = type;
		break;
	case SNDRV_DEVICE_TYPE_CONTROL:
		if (snd_BUG_ON(!card))
			return -EINVAL;
		minor = SNDRV_MINOR(card->number, type);
		break;
	case SNDRV_DEVICE_TYPE_HWDEP:
	case SNDRV_DEVICE_TYPE_RAWMIDI:
	case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
	case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
	case SNDRV_DEVICE_TYPE_COMPRESS:
		if (snd_BUG_ON(!card))
			return -EINVAL;
		minor = SNDRV_MINOR(card->number, type + dev);
		break;
	default:
		return -EINVAL;
	}
	if (snd_BUG_ON(minor < 0 || minor >= SNDRV_OS_MINORS))
		return -EINVAL;
	if (snd_minors[minor])
		return -EBUSY;
	return minor;
}
#endif

/**
 * snd_register_device - Register the ALSA device file for the card
 * @type: the device type, SNDRV_DEVICE_TYPE_XXX
 * @card: the card instance
 * @dev: the device index
 * @f_ops: the file operations
 * @private_data: user pointer for f_ops->open()
 * @device: the device to register
 *
 * Registers an ALSA device file for the given card.
 * The operators have to be set in reg parameter.
 *
 * Return: Zero if successful, or a negative error code on failure.
 */
int snd_register_device(int type, struct snd_card *card, int dev,
			const struct file_operations *f_ops,
			void *private_data, struct device *device)
{
	int minor;
	int err = 0;
	struct snd_minor *preg;

	if (snd_BUG_ON(!device))
		return -EINVAL;

	preg = kmalloc(sizeof *preg, GFP_KERNEL);
	if (preg == NULL)
		return -ENOMEM;
	preg->type = type;
	preg->card = card ? card->number : -1;
	preg->device = dev;
	preg->f_ops = f_ops;
	preg->private_data = private_data;
	preg->card_ptr = card;
	mutex_lock(&sound_mutex);
	minor = snd_find_free_minor(type, card, dev);
	if (minor < 0) {
		err = minor;
		goto error;
	}

	preg->dev = device;
	device->devt = MKDEV(major, minor);
	err = device_add(device);
	if (err < 0)
		goto error;

	snd_minors[minor] = preg;
 error:
	mutex_unlock(&sound_mutex);
	if (err < 0)
		kfree(preg);
	return err;
}
EXPORT_SYMBOL(snd_register_device);

/**
 * snd_unregister_device - unregister the device on the given card
 * @dev: the device instance
 *
 * Unregisters the device file already registered via
 * snd_register_device().
 *
 * Return: Zero if successful, or a negative error code on failure.
 */
int snd_unregister_device(struct device *dev)
{
	int minor;
	struct snd_minor *preg;

	mutex_lock(&sound_mutex);
	for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor) {
		preg = snd_minors[minor];
		if (preg && preg->dev == dev) {
			snd_minors[minor] = NULL;
			device_del(dev);
			kfree(preg);
			break;
		}
	}
	mutex_unlock(&sound_mutex);
	if (minor >= ARRAY_SIZE(snd_minors))
		return -ENOENT;
	return 0;
}
EXPORT_SYMBOL(snd_unregister_device);

#ifdef CONFIG_SND_PROC_FS
/*
 *  INFO PART
 */
static const char *snd_device_type_name(int type)
{
	switch (type) {
	case SNDRV_DEVICE_TYPE_CONTROL:
		return "control";
	case SNDRV_DEVICE_TYPE_HWDEP:
		return "hardware dependent";
	case SNDRV_DEVICE_TYPE_RAWMIDI:
		return "raw midi";
	case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
		return "digital audio playback";
	case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
		return "digital audio capture";
	case SNDRV_DEVICE_TYPE_SEQUENCER:
		return "sequencer";
	case SNDRV_DEVICE_TYPE_TIMER:
		return "timer";
	default:
		return "?";
	}
}

static void snd_minor_info_read(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
{
	int minor;
	struct snd_minor *mptr;

	mutex_lock(&sound_mutex);
	for (minor = 0; minor < SNDRV_OS_MINORS; ++minor) {
		if (!(mptr = snd_minors[minor]))
			continue;
		if (mptr->card >= 0) {
			if (mptr->device >= 0)
				snd_iprintf(buffer, "%3i: [%2i-%2i]: %s\n",
					    minor, mptr->card, mptr->device,
					    snd_device_type_name(mptr->type));
			else
				snd_iprintf(buffer, "%3i: [%2i]   : %s\n",
					    minor, mptr->card,
					    snd_device_type_name(mptr->type));
		} else
			snd_iprintf(buffer, "%3i:        : %s\n", minor,
				    snd_device_type_name(mptr->type));
	}
	mutex_unlock(&sound_mutex);
}

int __init snd_minor_info_init(void)
{
	struct snd_info_entry *entry;

	entry = snd_info_create_module_entry(THIS_MODULE, "devices", NULL);
	if (!entry)
		return -ENOMEM;
	entry->c.text.read = snd_minor_info_read;
	return snd_info_register(entry); /* freed in error path */
}
#endif /* CONFIG_SND_PROC_FS */

/*
 *  INIT PART
 */

static int __init alsa_sound_init(void)
{
	snd_major = major;
	snd_ecards_limit = cards_limit;
	if (register_chrdev(major, "alsa", &snd_fops)) {
		pr_err("ALSA core: unable to register native major device number %d\n", major);
		return -EIO;
	}
	if (snd_info_init() < 0) {
		unregister_chrdev(major, "alsa");
		return -ENOMEM;
	}
#ifndef MODULE
	pr_info("Advanced Linux Sound Architecture Driver Initialized.\n");
#endif
	return 0;
}

static void __exit alsa_sound_exit(void)
{
	snd_info_done();
	unregister_chrdev(major, "alsa");
}

subsys_initcall(alsa_sound_init);
module_exit(alsa_sound_exit);