aboutsummaryrefslogtreecommitdiff
path: root/sound/core/init.c
blob: f045f7db3ab42c9b44a07fd2fb992e1593ca693d (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
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
/*
 *  Initialization routines
 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
 *
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

#include <linux/init.h>
#include <linux/sched.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/ctype.h>
#include <linux/pm.h>

#include <sound/core.h>
#include <sound/control.h>
#include <sound/info.h>

static DEFINE_SPINLOCK(shutdown_lock);
static LIST_HEAD(shutdown_files);

static const struct file_operations snd_shutdown_f_ops;

static unsigned int snd_cards_lock;	/* locked for registering/using */
struct snd_card *snd_cards[SNDRV_CARDS];
EXPORT_SYMBOL(snd_cards);

static DEFINE_MUTEX(snd_card_mutex);

static char *slots[SNDRV_CARDS];
module_param_array(slots, charp, NULL, 0444);
MODULE_PARM_DESC(slots, "Module names assigned to the slots.");

/* return non-zero if the given index is already reserved for another
 * module via slots option
 */
static int module_slot_mismatch(struct module *module, int idx)
{
#ifdef MODULE
	char *s1, *s2;
	if (!module || !module->name || !slots[idx])
		return 0;
	s1 = slots[idx];
	s2 = module->name;
	/* compare module name strings
	 * hyphens are handled as equivalent with underscore
	 */
	for (;;) {
		char c1 = *s1++;
		char c2 = *s2++;
		if (c1 == '-')
			c1 = '_';
		if (c2 == '-')
			c2 = '_';
		if (c1 != c2)
			return 1;
		if (!c1)
			break;
	}
#endif
	return 0;
}

#if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
int (*snd_mixer_oss_notify_callback)(struct snd_card *card, int free_flag);
EXPORT_SYMBOL(snd_mixer_oss_notify_callback);
#endif

#ifdef CONFIG_PROC_FS
static void snd_card_id_read(struct snd_info_entry *entry,
			     struct snd_info_buffer *buffer)
{
	snd_iprintf(buffer, "%s\n", entry->card->id);
}

static inline int init_info_for_card(struct snd_card *card)
{
	int err;
	struct snd_info_entry *entry;

	if ((err = snd_info_card_register(card)) < 0) {
		snd_printd("unable to create card info\n");
		return err;
	}
	if ((entry = snd_info_create_card_entry(card, "id", card->proc_root)) == NULL) {
		snd_printd("unable to create card entry\n");
		return err;
	}
	entry->c.text.read = snd_card_id_read;
	if (snd_info_register(entry) < 0) {
		snd_info_free_entry(entry);
		entry = NULL;
	}
	card->proc_id = entry;
	return 0;
}
#else /* !CONFIG_PROC_FS */
#define init_info_for_card(card)
#endif

/**
 *  snd_card_new - create and initialize a soundcard structure
 *  @idx: card index (address) [0 ... (SNDRV_CARDS-1)]
 *  @xid: card identification (ASCII string)
 *  @module: top level module for locking
 *  @extra_size: allocate this extra size after the main soundcard structure
 *
 *  Creates and initializes a soundcard structure.
 *
 *  Returns kmallocated snd_card structure. Creates the ALSA control interface
 *  (which is blocked until snd_card_register function is called).
 */
struct snd_card *snd_card_new(int idx, const char *xid,
			 struct module *module, int extra_size)
{
	struct snd_card *card;
	int err;

	if (extra_size < 0)
		extra_size = 0;
	card = kzalloc(sizeof(*card) + extra_size, GFP_KERNEL);
	if (card == NULL)
		return NULL;
	if (xid) {
		if (!snd_info_check_reserved_words(xid))
			goto __error;
		strlcpy(card->id, xid, sizeof(card->id));
	}
	err = 0;
	mutex_lock(&snd_card_mutex);
	if (idx < 0) {
		int idx2;
		for (idx2 = 0; idx2 < SNDRV_CARDS; idx2++)
			/* idx == -1 == 0xffff means: take any free slot */
			if (~snd_cards_lock & idx & 1<<idx2) {
				if (module_slot_mismatch(module, idx2))
					continue;
				idx = idx2;
				if (idx >= snd_ecards_limit)
					snd_ecards_limit = idx + 1;
				break;
			}
	} else {
		 if (idx < snd_ecards_limit) {
			if (snd_cards_lock & (1 << idx))
				err = -EBUSY;	/* invalid */
		} else {
			if (idx < SNDRV_CARDS)
				snd_ecards_limit = idx + 1; /* increase the limit */
			else
				err = -ENODEV;
		}
	}
	if (idx < 0 || err < 0) {
		mutex_unlock(&snd_card_mutex);
		snd_printk(KERN_ERR "cannot find the slot for index %d (range 0-%i), error: %d\n",
			 idx, snd_ecards_limit - 1, err);
		goto __error;
	}
	snd_cards_lock |= 1 << idx;		/* lock it */
	mutex_unlock(&snd_card_mutex);
	card->number = idx;
	card->module = module;
	INIT_LIST_HEAD(&card->devices);
	init_rwsem(&card->controls_rwsem);
	rwlock_init(&card->ctl_files_rwlock);
	INIT_LIST_HEAD(&card->controls);
	INIT_LIST_HEAD(&card->ctl_files);
	spin_lock_init(&card->files_lock);
	init_waitqueue_head(&card->shutdown_sleep);
#ifdef CONFIG_PM
	mutex_init(&card->power_lock);
	init_waitqueue_head(&card->power_sleep);
#endif
	/* the control interface cannot be accessed from the user space until */
	/* snd_cards_bitmask and snd_cards are set with snd_card_register */
	if ((err = snd_ctl_create(card)) < 0) {
		snd_printd("unable to register control minors\n");
		goto __error;
	}
	if ((err = snd_info_card_create(card)) < 0) {
		snd_printd("unable to create card info\n");
		goto __error_ctl;
	}
	if (extra_size > 0)
		card->private_data = (char *)card + sizeof(struct snd_card);
	return card;

      __error_ctl:
	snd_device_free_all(card, SNDRV_DEV_CMD_PRE);
      __error:
	kfree(card);
      	return NULL;
}

EXPORT_SYMBOL(snd_card_new);

/* return non-zero if a card is already locked */
int snd_card_locked(int card)
{
	int locked;

	mutex_lock(&snd_card_mutex);
	locked = snd_cards_lock & (1 << card);
	mutex_unlock(&snd_card_mutex);
	return locked;
}

static loff_t snd_disconnect_llseek(struct file *file, loff_t offset, int orig)
{
	return -ENODEV;
}

static ssize_t snd_disconnect_read(struct file *file, char __user *buf,
				   size_t count, loff_t *offset)
{
	return -ENODEV;
}

static ssize_t snd_disconnect_write(struct file *file, const char __user *buf,
				    size_t count, loff_t *offset)
{
	return -ENODEV;
}

static int snd_disconnect_release(struct inode *inode, struct file *file)
{
	struct snd_monitor_file *df = NULL, *_df;

	spin_lock(&shutdown_lock);
	list_for_each_entry(_df, &shutdown_files, shutdown_list) {
		if (_df->file == file) {
			df = _df;
			break;
		}
	}
	spin_unlock(&shutdown_lock);

	if (likely(df))
		return df->disconnected_f_op->release(inode, file);

	panic("%s(%p, %p) failed!", __func__, inode, file);
}

static unsigned int snd_disconnect_poll(struct file * file, poll_table * wait)
{
	return POLLERR | POLLNVAL;
}

static long snd_disconnect_ioctl(struct file *file,
				 unsigned int cmd, unsigned long arg)
{
	return -ENODEV;
}

static int snd_disconnect_mmap(struct file *file, struct vm_area_struct *vma)
{
	return -ENODEV;
}

static int snd_disconnect_fasync(int fd, struct file *file, int on)
{
	return -ENODEV;
}

static const struct file_operations snd_shutdown_f_ops =
{
	.owner = 	THIS_MODULE,
	.llseek =	snd_disconnect_llseek,
	.read = 	snd_disconnect_read,
	.write =	snd_disconnect_write,
	.release =	snd_disconnect_release,
	.poll =		snd_disconnect_poll,
	.unlocked_ioctl = snd_disconnect_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl = snd_disconnect_ioctl,
#endif
	.mmap =		snd_disconnect_mmap,
	.fasync =	snd_disconnect_fasync
};

/**
 *  snd_card_disconnect - disconnect all APIs from the file-operations (user space)
 *  @card: soundcard structure
 *
 *  Disconnects all APIs from the file-operations (user space).
 *
 *  Returns zero, otherwise a negative error code.
 *
 *  Note: The current implementation replaces all active file->f_op with special
 *        dummy file operations (they do nothing except release).
 */
int snd_card_disconnect(struct snd_card *card)
{
	struct snd_monitor_file *mfile;
	struct file *file;
	int err;

	spin_lock(&card->files_lock);
	if (card->shutdown) {
		spin_unlock(&card->files_lock);
		return 0;
	}
	card->shutdown = 1;
	spin_unlock(&card->files_lock);

	/* phase 1: disable fops (user space) operations for ALSA API */
	mutex_lock(&snd_card_mutex);
	snd_cards[card->number] = NULL;
	mutex_unlock(&snd_card_mutex);
	
	/* phase 2: replace file->f_op with special dummy operations */
	
	spin_lock(&card->files_lock);
	mfile = card->files;
	while (mfile) {
		file = mfile->file;

		/* it's critical part, use endless loop */
		/* we have no room to fail */
		mfile->disconnected_f_op = mfile->file->f_op;

		spin_lock(&shutdown_lock);
		list_add(&mfile->shutdown_list, &shutdown_files);
		spin_unlock(&shutdown_lock);

		mfile->file->f_op = &snd_shutdown_f_ops;
		fops_get(mfile->file->f_op);
		
		mfile = mfile->next;
	}
	spin_unlock(&card->files_lock);	

	/* phase 3: notify all connected devices about disconnection */
	/* at this point, they cannot respond to any calls except release() */

#if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
	if (snd_mixer_oss_notify_callback)
		snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_DISCONNECT);
#endif

	/* notify all devices that we are disconnected */
	err = snd_device_disconnect_all(card);
	if (err < 0)
		snd_printk(KERN_ERR "not all devices for card %i can be disconnected\n", card->number);

	snd_info_card_disconnect(card);
	return 0;	
}

EXPORT_SYMBOL(snd_card_disconnect);

/**
 *  snd_card_free - frees given soundcard structure
 *  @card: soundcard structure
 *
 *  This function releases the soundcard structure and the all assigned
 *  devices automatically.  That is, you don't have to release the devices
 *  by yourself.
 *
 *  Returns zero. Frees all associated devices and frees the control
 *  interface associated to given soundcard.
 */
static int snd_card_do_free(struct snd_card *card)
{
#if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
	if (snd_mixer_oss_notify_callback)
		snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_FREE);
#endif
	if (snd_device_free_all(card, SNDRV_DEV_CMD_PRE) < 0) {
		snd_printk(KERN_ERR "unable to free all devices (pre)\n");
		/* Fatal, but this situation should never occur */
	}
	if (snd_device_free_all(card, SNDRV_DEV_CMD_NORMAL) < 0) {
		snd_printk(KERN_ERR "unable to free all devices (normal)\n");
		/* Fatal, but this situation should never occur */
	}
	if (snd_device_free_all(card, SNDRV_DEV_CMD_POST) < 0) {
		snd_printk(KERN_ERR "unable to free all devices (post)\n");
		/* Fatal, but this situation should never occur */
	}
	if (card->private_free)
		card->private_free(card);
	snd_info_free_entry(card->proc_id);
	if (snd_info_card_free(card) < 0) {
		snd_printk(KERN_WARNING "unable to free card info\n");
		/* Not fatal error */
	}
#ifndef CONFIG_SYSFS_DEPRECATED
	if (card->card_dev)
		device_unregister(card->card_dev);
#endif
	kfree(card);
	return 0;
}

static int snd_card_free_prepare(struct snd_card *card)
{
	if (card == NULL)
		return -EINVAL;
	(void) snd_card_disconnect(card);
	mutex_lock(&snd_card_mutex);
	snd_cards[card->number] = NULL;
	snd_cards_lock &= ~(1 << card->number);
	mutex_unlock(&snd_card_mutex);
#ifdef CONFIG_PM
	wake_up(&card->power_sleep);
#endif
	return 0;
}

int snd_card_free_when_closed(struct snd_card *card)
{
	int free_now = 0;
	int ret = snd_card_free_prepare(card);
	if (ret)
		return ret;

	spin_lock(&card->files_lock);
	if (card->files == NULL)
		free_now = 1;
	else
		card->free_on_last_close = 1;
	spin_unlock(&card->files_lock);

	if (free_now)
		snd_card_do_free(card);
	return 0;
}

EXPORT_SYMBOL(snd_card_free_when_closed);

int snd_card_free(struct snd_card *card)
{
	int ret = snd_card_free_prepare(card);
	if (ret)
		return ret;

	/* wait, until all devices are ready for the free operation */
	wait_event(card->shutdown_sleep, card->files == NULL);
	snd_card_do_free(card);
	return 0;
}

EXPORT_SYMBOL(snd_card_free);

static void choose_default_id(struct snd_card *card)
{
	int i, len, idx_flag = 0, loops = SNDRV_CARDS;
	char *id, *spos;
	
	id = spos = card->shortname;	
	while (*id != '\0') {
		if (*id == ' ')
			spos = id + 1;
		id++;
	}
	id = card->id;
	while (*spos != '\0' && !isalnum(*spos))
		spos++;
	if (isdigit(*spos))
		*id++ = isalpha(card->shortname[0]) ? card->shortname[0] : 'D';
	while (*spos != '\0' && (size_t)(id - card->id) < sizeof(card->id) - 1) {
		if (isalnum(*spos))
			*id++ = *spos;
		spos++;
	}
	*id = '\0';

	id = card->id;
	
	if (*id == '\0')
		strcpy(id, "default");

	while (1) {
	      	if (loops-- == 0) {
      			snd_printk(KERN_ERR "unable to choose default card id (%s)\n", id);
      			strcpy(card->id, card->proc_root->name);
      			return;
      		}
	      	if (!snd_info_check_reserved_words(id))
      			goto __change;
		for (i = 0; i < snd_ecards_limit; i++) {
			if (snd_cards[i] && !strcmp(snd_cards[i]->id, id))
				goto __change;
		}
		break;

	      __change:
		len = strlen(id);
		if (idx_flag) {
			if (id[len-1] != '9')
				id[len-1]++;
			else
				id[len-1] = 'A';
		} else if ((size_t)len <= sizeof(card->id) - 3) {
			strcat(id, "_1");
			idx_flag++;
		} else {
			spos = id + len - 2;
			if ((size_t)len <= sizeof(card->id) - 2)
				spos++;
			*spos++ = '_';
			*spos++ = '1';
			*spos++ = '\0';
			idx_flag++;
		}
	}
}

/**
 *  snd_card_register - register the soundcard
 *  @card: soundcard structure
 *
 *  This function registers all the devices assigned to the soundcard.
 *  Until calling this, the ALSA control interface is blocked from the
 *  external accesses.  Thus, you should call this function at the end
 *  of the initialization of the card.
 *
 *  Returns zero otherwise a negative error code if the registrain failed.
 */
int snd_card_register(struct snd_card *card)
{
	int err;

	snd_assert(card != NULL, return -EINVAL);
#ifndef CONFIG_SYSFS_DEPRECATED
	if (!card->card_dev) {
		card->card_dev = device_create(sound_class, card->dev, 0,
					       "card%i", card->number);
		if (IS_ERR(card->card_dev))
			card->card_dev = NULL;
	}
#endif
	if ((err = snd_device_register_all(card)) < 0)
		return err;
	mutex_lock(&snd_card_mutex);
	if (snd_cards[card->number]) {
		/* already registered */
		mutex_unlock(&snd_card_mutex);
		return 0;
	}
	if (card->id[0] == '\0')
		choose_default_id(card);
	snd_cards[card->number] = card;
	mutex_unlock(&snd_card_mutex);
	init_info_for_card(card);
#if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
	if (snd_mixer_oss_notify_callback)
		snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_REGISTER);
#endif
	return 0;
}

EXPORT_SYMBOL(snd_card_register);

#ifdef CONFIG_PROC_FS
static struct snd_info_entry *snd_card_info_entry;

static void snd_card_info_read(struct snd_info_entry *entry,
			       struct snd_info_buffer *buffer)
{
	int idx, count;
	struct snd_card *card;

	for (idx = count = 0; idx < SNDRV_CARDS; idx++) {
		mutex_lock(&snd_card_mutex);
		if ((card = snd_cards[idx]) != NULL) {
			count++;
			snd_iprintf(buffer, "%2i [%-15s]: %s - %s\n",
					idx,
					card->id,
					card->driver,
					card->shortname);
			snd_iprintf(buffer, "                      %s\n",
					card->longname);
		}
		mutex_unlock(&snd_card_mutex);
	}
	if (!count)
		snd_iprintf(buffer, "--- no soundcards ---\n");
}

#ifdef CONFIG_SND_OSSEMUL

void snd_card_info_read_oss(struct snd_info_buffer *buffer)
{
	int idx, count;
	struct snd_card *card;

	for (idx = count = 0; idx < SNDRV_CARDS; idx++) {
		mutex_lock(&snd_card_mutex);
		if ((card = snd_cards[idx]) != NULL) {
			count++;
			snd_iprintf(buffer, "%s\n", card->longname);
		}
		mutex_unlock(&snd_card_mutex);
	}
	if (!count) {
		snd_iprintf(buffer, "--- no soundcards ---\n");
	}
}

#endif

#ifdef MODULE
static struct snd_info_entry *snd_card_module_info_entry;
static void snd_card_module_info_read(struct snd_info_entry *entry,
				      struct snd_info_buffer *buffer)
{
	int idx;
	struct snd_card *card;

	for (idx = 0; idx < SNDRV_CARDS; idx++) {
		mutex_lock(&snd_card_mutex);
		if ((card = snd_cards[idx]) != NULL)
			snd_iprintf(buffer, "%2i %s\n",
				    idx, card->module->name);
		mutex_unlock(&snd_card_mutex);
	}
}
#endif

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

	entry = snd_info_create_module_entry(THIS_MODULE, "cards", NULL);
	if (! entry)
		return -ENOMEM;
	entry->c.text.read = snd_card_info_read;
	if (snd_info_register(entry) < 0) {
		snd_info_free_entry(entry);
		return -ENOMEM;
	}
	snd_card_info_entry = entry;

#ifdef MODULE
	entry = snd_info_create_module_entry(THIS_MODULE, "modules", NULL);
	if (entry) {
		entry->c.text.read = snd_card_module_info_read;
		if (snd_info_register(entry) < 0)
			snd_info_free_entry(entry);
		else
			snd_card_module_info_entry = entry;
	}
#endif

	return 0;
}

int __exit snd_card_info_done(void)
{
	snd_info_free_entry(snd_card_info_entry);
#ifdef MODULE
	snd_info_free_entry(snd_card_module_info_entry);
#endif
	return 0;
}

#endif /* CONFIG_PROC_FS */

/**
 *  snd_component_add - add a component string
 *  @card: soundcard structure
 *  @component: the component id string
 *
 *  This function adds the component id string to the supported list.
 *  The component can be referred from the alsa-lib.
 *
 *  Returns zero otherwise a negative error code.
 */
  
int snd_component_add(struct snd_card *card, const char *component)
{
	char *ptr;
	int len = strlen(component);

	ptr = strstr(card->components, component);
	if (ptr != NULL) {
		if (ptr[len] == '\0' || ptr[len] == ' ')	/* already there */
			return 1;
	}
	if (strlen(card->components) + 1 + len + 1 > sizeof(card->components)) {
		snd_BUG();
		return -ENOMEM;
	}
	if (card->components[0] != '\0')
		strcat(card->components, " ");
	strcat(card->components, component);
	return 0;
}

EXPORT_SYMBOL(snd_component_add);

/**
 *  snd_card_file_add - add the file to the file list of the card
 *  @card: soundcard structure
 *  @file: file pointer
 *
 *  This function adds the file to the file linked-list of the card.
 *  This linked-list is used to keep tracking the connection state,
 *  and to avoid the release of busy resources by hotplug.
 *
 *  Returns zero or a negative error code.
 */
int snd_card_file_add(struct snd_card *card, struct file *file)
{
	struct snd_monitor_file *mfile;

	mfile = kmalloc(sizeof(*mfile), GFP_KERNEL);
	if (mfile == NULL)
		return -ENOMEM;
	mfile->file = file;
	mfile->disconnected_f_op = NULL;
	mfile->next = NULL;
	spin_lock(&card->files_lock);
	if (card->shutdown) {
		spin_unlock(&card->files_lock);
		kfree(mfile);
		return -ENODEV;
	}
	mfile->next = card->files;
	card->files = mfile;
	spin_unlock(&card->files_lock);
	return 0;
}

EXPORT_SYMBOL(snd_card_file_add);

/**
 *  snd_card_file_remove - remove the file from the file list
 *  @card: soundcard structure
 *  @file: file pointer
 *
 *  This function removes the file formerly added to the card via
 *  snd_card_file_add() function.
 *  If all files are removed and snd_card_free_when_closed() was
 *  called beforehand, it processes the pending release of
 *  resources.
 *
 *  Returns zero or a negative error code.
 */
int snd_card_file_remove(struct snd_card *card, struct file *file)
{
	struct snd_monitor_file *mfile, *pfile = NULL;
	int last_close = 0;

	spin_lock(&card->files_lock);
	mfile = card->files;
	while (mfile) {
		if (mfile->file == file) {
			if (pfile)
				pfile->next = mfile->next;
			else
				card->files = mfile->next;
			break;
		}
		pfile = mfile;
		mfile = mfile->next;
	}
	if (mfile && mfile->disconnected_f_op) {
		fops_put(mfile->disconnected_f_op);
		spin_lock(&shutdown_lock);
		list_del(&mfile->shutdown_list);
		spin_unlock(&shutdown_lock);
	}
	if (card->files == NULL)
		last_close = 1;
	spin_unlock(&card->files_lock);
	if (last_close) {
		wake_up(&card->shutdown_sleep);
		if (card->free_on_last_close)
			snd_card_do_free(card);
	}
	if (!mfile) {
		snd_printk(KERN_ERR "ALSA card file remove problem (%p)\n", file);
		return -ENOENT;
	}
	kfree(mfile);
	return 0;
}

EXPORT_SYMBOL(snd_card_file_remove);

#ifdef CONFIG_PM
/**
 *  snd_power_wait - wait until the power-state is changed.
 *  @card: soundcard structure
 *  @power_state: expected power state
 *
 *  Waits until the power-state is changed.
 *
 *  Note: the power lock must be active before call.
 */
int snd_power_wait(struct snd_card *card, unsigned int power_state)
{
	wait_queue_t wait;
	int result = 0;

	/* fastpath */
	if (snd_power_get_state(card) == power_state)
		return 0;
	init_waitqueue_entry(&wait, current);
	add_wait_queue(&card->power_sleep, &wait);
	while (1) {
		if (card->shutdown) {
			result = -ENODEV;
			break;
		}
		if (snd_power_get_state(card) == power_state)
			break;
		set_current_state(TASK_UNINTERRUPTIBLE);
		snd_power_unlock(card);
		schedule_timeout(30 * HZ);
		snd_power_lock(card);
	}
	remove_wait_queue(&card->power_sleep, &wait);
	return result;
}

EXPORT_SYMBOL(snd_power_wait);
#endif /* CONFIG_PM */