xref: /openbmc/linux/sound/core/info.c (revision b593bce5) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  Information interface for ALSA driver
4  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
5  */
6 
7 #include <linux/init.h>
8 #include <linux/time.h>
9 #include <linux/mm.h>
10 #include <linux/slab.h>
11 #include <linux/string.h>
12 #include <linux/module.h>
13 #include <sound/core.h>
14 #include <sound/minors.h>
15 #include <sound/info.h>
16 #include <linux/utsname.h>
17 #include <linux/proc_fs.h>
18 #include <linux/mutex.h>
19 #include <stdarg.h>
20 
21 int snd_info_check_reserved_words(const char *str)
22 {
23 	static char *reserved[] =
24 	{
25 		"version",
26 		"meminfo",
27 		"memdebug",
28 		"detect",
29 		"devices",
30 		"oss",
31 		"cards",
32 		"timers",
33 		"synth",
34 		"pcm",
35 		"seq",
36 		NULL
37 	};
38 	char **xstr = reserved;
39 
40 	while (*xstr) {
41 		if (!strcmp(*xstr, str))
42 			return 0;
43 		xstr++;
44 	}
45 	if (!strncmp(str, "card", 4))
46 		return 0;
47 	return 1;
48 }
49 
50 static DEFINE_MUTEX(info_mutex);
51 
52 struct snd_info_private_data {
53 	struct snd_info_buffer *rbuffer;
54 	struct snd_info_buffer *wbuffer;
55 	struct snd_info_entry *entry;
56 	void *file_private_data;
57 };
58 
59 static int snd_info_version_init(void);
60 static void snd_info_disconnect(struct snd_info_entry *entry);
61 
62 /*
63 
64  */
65 
66 static struct snd_info_entry *snd_proc_root;
67 struct snd_info_entry *snd_seq_root;
68 EXPORT_SYMBOL(snd_seq_root);
69 
70 #ifdef CONFIG_SND_OSSEMUL
71 struct snd_info_entry *snd_oss_root;
72 #endif
73 
74 static int alloc_info_private(struct snd_info_entry *entry,
75 			      struct snd_info_private_data **ret)
76 {
77 	struct snd_info_private_data *data;
78 
79 	if (!entry || !entry->p)
80 		return -ENODEV;
81 	if (!try_module_get(entry->module))
82 		return -EFAULT;
83 	data = kzalloc(sizeof(*data), GFP_KERNEL);
84 	if (!data) {
85 		module_put(entry->module);
86 		return -ENOMEM;
87 	}
88 	data->entry = entry;
89 	*ret = data;
90 	return 0;
91 }
92 
93 static bool valid_pos(loff_t pos, size_t count)
94 {
95 	if (pos < 0 || (long) pos != pos || (ssize_t) count < 0)
96 		return false;
97 	if ((unsigned long) pos + (unsigned long) count < (unsigned long) pos)
98 		return false;
99 	return true;
100 }
101 
102 /*
103  * file ops for binary proc files
104  */
105 static loff_t snd_info_entry_llseek(struct file *file, loff_t offset, int orig)
106 {
107 	struct snd_info_private_data *data;
108 	struct snd_info_entry *entry;
109 	loff_t ret = -EINVAL, size;
110 
111 	data = file->private_data;
112 	entry = data->entry;
113 	mutex_lock(&entry->access);
114 	if (entry->c.ops->llseek) {
115 		offset = entry->c.ops->llseek(entry,
116 					      data->file_private_data,
117 					      file, offset, orig);
118 		goto out;
119 	}
120 
121 	size = entry->size;
122 	switch (orig) {
123 	case SEEK_SET:
124 		break;
125 	case SEEK_CUR:
126 		offset += file->f_pos;
127 		break;
128 	case SEEK_END:
129 		if (!size)
130 			goto out;
131 		offset += size;
132 		break;
133 	default:
134 		goto out;
135 	}
136 	if (offset < 0)
137 		goto out;
138 	if (size && offset > size)
139 		offset = size;
140 	file->f_pos = offset;
141 	ret = offset;
142  out:
143 	mutex_unlock(&entry->access);
144 	return ret;
145 }
146 
147 static ssize_t snd_info_entry_read(struct file *file, char __user *buffer,
148 				   size_t count, loff_t * offset)
149 {
150 	struct snd_info_private_data *data = file->private_data;
151 	struct snd_info_entry *entry = data->entry;
152 	size_t size;
153 	loff_t pos;
154 
155 	pos = *offset;
156 	if (!valid_pos(pos, count))
157 		return -EIO;
158 	if (pos >= entry->size)
159 		return 0;
160 	size = entry->size - pos;
161 	size = min(count, size);
162 	size = entry->c.ops->read(entry, data->file_private_data,
163 				  file, buffer, size, pos);
164 	if ((ssize_t) size > 0)
165 		*offset = pos + size;
166 	return size;
167 }
168 
169 static ssize_t snd_info_entry_write(struct file *file, const char __user *buffer,
170 				    size_t count, loff_t * offset)
171 {
172 	struct snd_info_private_data *data = file->private_data;
173 	struct snd_info_entry *entry = data->entry;
174 	ssize_t size = 0;
175 	loff_t pos;
176 
177 	pos = *offset;
178 	if (!valid_pos(pos, count))
179 		return -EIO;
180 	if (count > 0) {
181 		size_t maxsize = entry->size - pos;
182 		count = min(count, maxsize);
183 		size = entry->c.ops->write(entry, data->file_private_data,
184 					   file, buffer, count, pos);
185 	}
186 	if (size > 0)
187 		*offset = pos + size;
188 	return size;
189 }
190 
191 static __poll_t snd_info_entry_poll(struct file *file, poll_table *wait)
192 {
193 	struct snd_info_private_data *data = file->private_data;
194 	struct snd_info_entry *entry = data->entry;
195 	__poll_t mask = 0;
196 
197 	if (entry->c.ops->poll)
198 		return entry->c.ops->poll(entry,
199 					  data->file_private_data,
200 					  file, wait);
201 	if (entry->c.ops->read)
202 		mask |= EPOLLIN | EPOLLRDNORM;
203 	if (entry->c.ops->write)
204 		mask |= EPOLLOUT | EPOLLWRNORM;
205 	return mask;
206 }
207 
208 static long snd_info_entry_ioctl(struct file *file, unsigned int cmd,
209 				unsigned long arg)
210 {
211 	struct snd_info_private_data *data = file->private_data;
212 	struct snd_info_entry *entry = data->entry;
213 
214 	if (!entry->c.ops->ioctl)
215 		return -ENOTTY;
216 	return entry->c.ops->ioctl(entry, data->file_private_data,
217 				   file, cmd, arg);
218 }
219 
220 static int snd_info_entry_mmap(struct file *file, struct vm_area_struct *vma)
221 {
222 	struct inode *inode = file_inode(file);
223 	struct snd_info_private_data *data;
224 	struct snd_info_entry *entry;
225 
226 	data = file->private_data;
227 	if (data == NULL)
228 		return 0;
229 	entry = data->entry;
230 	if (!entry->c.ops->mmap)
231 		return -ENXIO;
232 	return entry->c.ops->mmap(entry, data->file_private_data,
233 				  inode, file, vma);
234 }
235 
236 static int snd_info_entry_open(struct inode *inode, struct file *file)
237 {
238 	struct snd_info_entry *entry = PDE_DATA(inode);
239 	struct snd_info_private_data *data;
240 	int mode, err;
241 
242 	mutex_lock(&info_mutex);
243 	err = alloc_info_private(entry, &data);
244 	if (err < 0)
245 		goto unlock;
246 
247 	mode = file->f_flags & O_ACCMODE;
248 	if (((mode == O_RDONLY || mode == O_RDWR) && !entry->c.ops->read) ||
249 	    ((mode == O_WRONLY || mode == O_RDWR) && !entry->c.ops->write)) {
250 		err = -ENODEV;
251 		goto error;
252 	}
253 
254 	if (entry->c.ops->open) {
255 		err = entry->c.ops->open(entry, mode, &data->file_private_data);
256 		if (err < 0)
257 			goto error;
258 	}
259 
260 	file->private_data = data;
261 	mutex_unlock(&info_mutex);
262 	return 0;
263 
264  error:
265 	kfree(data);
266 	module_put(entry->module);
267  unlock:
268 	mutex_unlock(&info_mutex);
269 	return err;
270 }
271 
272 static int snd_info_entry_release(struct inode *inode, struct file *file)
273 {
274 	struct snd_info_private_data *data = file->private_data;
275 	struct snd_info_entry *entry = data->entry;
276 
277 	if (entry->c.ops->release)
278 		entry->c.ops->release(entry, file->f_flags & O_ACCMODE,
279 				      data->file_private_data);
280 	module_put(entry->module);
281 	kfree(data);
282 	return 0;
283 }
284 
285 static const struct file_operations snd_info_entry_operations =
286 {
287 	.owner =		THIS_MODULE,
288 	.llseek =		snd_info_entry_llseek,
289 	.read =			snd_info_entry_read,
290 	.write =		snd_info_entry_write,
291 	.poll =			snd_info_entry_poll,
292 	.unlocked_ioctl =	snd_info_entry_ioctl,
293 	.mmap =			snd_info_entry_mmap,
294 	.open =			snd_info_entry_open,
295 	.release =		snd_info_entry_release,
296 };
297 
298 /*
299  * file ops for text proc files
300  */
301 static ssize_t snd_info_text_entry_write(struct file *file,
302 					 const char __user *buffer,
303 					 size_t count, loff_t *offset)
304 {
305 	struct seq_file *m = file->private_data;
306 	struct snd_info_private_data *data = m->private;
307 	struct snd_info_entry *entry = data->entry;
308 	struct snd_info_buffer *buf;
309 	loff_t pos;
310 	size_t next;
311 	int err = 0;
312 
313 	if (!entry->c.text.write)
314 		return -EIO;
315 	pos = *offset;
316 	if (!valid_pos(pos, count))
317 		return -EIO;
318 	next = pos + count;
319 	/* don't handle too large text inputs */
320 	if (next > 16 * 1024)
321 		return -EIO;
322 	mutex_lock(&entry->access);
323 	buf = data->wbuffer;
324 	if (!buf) {
325 		data->wbuffer = buf = kzalloc(sizeof(*buf), GFP_KERNEL);
326 		if (!buf) {
327 			err = -ENOMEM;
328 			goto error;
329 		}
330 	}
331 	if (next > buf->len) {
332 		char *nbuf = kvzalloc(PAGE_ALIGN(next), GFP_KERNEL);
333 		if (!nbuf) {
334 			err = -ENOMEM;
335 			goto error;
336 		}
337 		kvfree(buf->buffer);
338 		buf->buffer = nbuf;
339 		buf->len = PAGE_ALIGN(next);
340 	}
341 	if (copy_from_user(buf->buffer + pos, buffer, count)) {
342 		err = -EFAULT;
343 		goto error;
344 	}
345 	buf->size = next;
346  error:
347 	mutex_unlock(&entry->access);
348 	if (err < 0)
349 		return err;
350 	*offset = next;
351 	return count;
352 }
353 
354 static int snd_info_seq_show(struct seq_file *seq, void *p)
355 {
356 	struct snd_info_private_data *data = seq->private;
357 	struct snd_info_entry *entry = data->entry;
358 
359 	if (!entry->c.text.read) {
360 		return -EIO;
361 	} else {
362 		data->rbuffer->buffer = (char *)seq; /* XXX hack! */
363 		entry->c.text.read(entry, data->rbuffer);
364 	}
365 	return 0;
366 }
367 
368 static int snd_info_text_entry_open(struct inode *inode, struct file *file)
369 {
370 	struct snd_info_entry *entry = PDE_DATA(inode);
371 	struct snd_info_private_data *data;
372 	int err;
373 
374 	mutex_lock(&info_mutex);
375 	err = alloc_info_private(entry, &data);
376 	if (err < 0)
377 		goto unlock;
378 
379 	data->rbuffer = kzalloc(sizeof(*data->rbuffer), GFP_KERNEL);
380 	if (!data->rbuffer) {
381 		err = -ENOMEM;
382 		goto error;
383 	}
384 	if (entry->size)
385 		err = single_open_size(file, snd_info_seq_show, data,
386 				       entry->size);
387 	else
388 		err = single_open(file, snd_info_seq_show, data);
389 	if (err < 0)
390 		goto error;
391 	mutex_unlock(&info_mutex);
392 	return 0;
393 
394  error:
395 	kfree(data->rbuffer);
396 	kfree(data);
397 	module_put(entry->module);
398  unlock:
399 	mutex_unlock(&info_mutex);
400 	return err;
401 }
402 
403 static int snd_info_text_entry_release(struct inode *inode, struct file *file)
404 {
405 	struct seq_file *m = file->private_data;
406 	struct snd_info_private_data *data = m->private;
407 	struct snd_info_entry *entry = data->entry;
408 
409 	if (data->wbuffer && entry->c.text.write)
410 		entry->c.text.write(entry, data->wbuffer);
411 
412 	single_release(inode, file);
413 	kfree(data->rbuffer);
414 	if (data->wbuffer) {
415 		kvfree(data->wbuffer->buffer);
416 		kfree(data->wbuffer);
417 	}
418 
419 	module_put(entry->module);
420 	kfree(data);
421 	return 0;
422 }
423 
424 static const struct file_operations snd_info_text_entry_ops =
425 {
426 	.owner =		THIS_MODULE,
427 	.open =			snd_info_text_entry_open,
428 	.release =		snd_info_text_entry_release,
429 	.write =		snd_info_text_entry_write,
430 	.llseek =		seq_lseek,
431 	.read =			seq_read,
432 };
433 
434 static struct snd_info_entry *create_subdir(struct module *mod,
435 					    const char *name)
436 {
437 	struct snd_info_entry *entry;
438 
439 	entry = snd_info_create_module_entry(mod, name, NULL);
440 	if (!entry)
441 		return NULL;
442 	entry->mode = S_IFDIR | 0555;
443 	if (snd_info_register(entry) < 0) {
444 		snd_info_free_entry(entry);
445 		return NULL;
446 	}
447 	return entry;
448 }
449 
450 static struct snd_info_entry *
451 snd_info_create_entry(const char *name, struct snd_info_entry *parent,
452 		      struct module *module);
453 
454 int __init snd_info_init(void)
455 {
456 	snd_proc_root = snd_info_create_entry("asound", NULL, THIS_MODULE);
457 	if (!snd_proc_root)
458 		return -ENOMEM;
459 	snd_proc_root->mode = S_IFDIR | 0555;
460 	snd_proc_root->p = proc_mkdir("asound", NULL);
461 	if (!snd_proc_root->p)
462 		goto error;
463 #ifdef CONFIG_SND_OSSEMUL
464 	snd_oss_root = create_subdir(THIS_MODULE, "oss");
465 	if (!snd_oss_root)
466 		goto error;
467 #endif
468 #if IS_ENABLED(CONFIG_SND_SEQUENCER)
469 	snd_seq_root = create_subdir(THIS_MODULE, "seq");
470 	if (!snd_seq_root)
471 		goto error;
472 #endif
473 	if (snd_info_version_init() < 0 ||
474 	    snd_minor_info_init() < 0 ||
475 	    snd_minor_info_oss_init() < 0 ||
476 	    snd_card_info_init() < 0 ||
477 	    snd_info_minor_register() < 0)
478 		goto error;
479 	return 0;
480 
481  error:
482 	snd_info_free_entry(snd_proc_root);
483 	return -ENOMEM;
484 }
485 
486 int __exit snd_info_done(void)
487 {
488 	snd_info_free_entry(snd_proc_root);
489 	return 0;
490 }
491 
492 static void snd_card_id_read(struct snd_info_entry *entry,
493 			     struct snd_info_buffer *buffer)
494 {
495 	struct snd_card *card = entry->private_data;
496 
497 	snd_iprintf(buffer, "%s\n", card->id);
498 }
499 
500 /*
501  * create a card proc file
502  * called from init.c
503  */
504 int snd_info_card_create(struct snd_card *card)
505 {
506 	char str[8];
507 	struct snd_info_entry *entry;
508 
509 	if (snd_BUG_ON(!card))
510 		return -ENXIO;
511 
512 	sprintf(str, "card%i", card->number);
513 	entry = create_subdir(card->module, str);
514 	if (!entry)
515 		return -ENOMEM;
516 	card->proc_root = entry;
517 
518 	return snd_card_ro_proc_new(card, "id", card, snd_card_id_read);
519 }
520 
521 /*
522  * register the card proc file
523  * called from init.c
524  * can be called multiple times for reinitialization
525  */
526 int snd_info_card_register(struct snd_card *card)
527 {
528 	struct proc_dir_entry *p;
529 	int err;
530 
531 	if (snd_BUG_ON(!card))
532 		return -ENXIO;
533 
534 	err = snd_info_register(card->proc_root);
535 	if (err < 0)
536 		return err;
537 
538 	if (!strcmp(card->id, card->proc_root->name))
539 		return 0;
540 
541 	if (card->proc_root_link)
542 		return 0;
543 	p = proc_symlink(card->id, snd_proc_root->p, card->proc_root->name);
544 	if (!p)
545 		return -ENOMEM;
546 	card->proc_root_link = p;
547 	return 0;
548 }
549 
550 /*
551  * called on card->id change
552  */
553 void snd_info_card_id_change(struct snd_card *card)
554 {
555 	mutex_lock(&info_mutex);
556 	if (card->proc_root_link) {
557 		proc_remove(card->proc_root_link);
558 		card->proc_root_link = NULL;
559 	}
560 	if (strcmp(card->id, card->proc_root->name))
561 		card->proc_root_link = proc_symlink(card->id,
562 						    snd_proc_root->p,
563 						    card->proc_root->name);
564 	mutex_unlock(&info_mutex);
565 }
566 
567 /*
568  * de-register the card proc file
569  * called from init.c
570  */
571 void snd_info_card_disconnect(struct snd_card *card)
572 {
573 	if (!card)
574 		return;
575 	mutex_lock(&info_mutex);
576 	proc_remove(card->proc_root_link);
577 	card->proc_root_link = NULL;
578 	if (card->proc_root)
579 		snd_info_disconnect(card->proc_root);
580 	mutex_unlock(&info_mutex);
581 }
582 
583 /*
584  * release the card proc file resources
585  * called from init.c
586  */
587 int snd_info_card_free(struct snd_card *card)
588 {
589 	if (!card)
590 		return 0;
591 	snd_info_free_entry(card->proc_root);
592 	card->proc_root = NULL;
593 	return 0;
594 }
595 
596 
597 /**
598  * snd_info_get_line - read one line from the procfs buffer
599  * @buffer: the procfs buffer
600  * @line: the buffer to store
601  * @len: the max. buffer size
602  *
603  * Reads one line from the buffer and stores the string.
604  *
605  * Return: Zero if successful, or 1 if error or EOF.
606  */
607 int snd_info_get_line(struct snd_info_buffer *buffer, char *line, int len)
608 {
609 	int c = -1;
610 
611 	if (snd_BUG_ON(!buffer || !buffer->buffer))
612 		return 1;
613 	if (len <= 0 || buffer->stop || buffer->error)
614 		return 1;
615 	while (!buffer->stop) {
616 		c = buffer->buffer[buffer->curr++];
617 		if (buffer->curr >= buffer->size)
618 			buffer->stop = 1;
619 		if (c == '\n')
620 			break;
621 		if (len > 1) {
622 			len--;
623 			*line++ = c;
624 		}
625 	}
626 	*line = '\0';
627 	return 0;
628 }
629 EXPORT_SYMBOL(snd_info_get_line);
630 
631 /**
632  * snd_info_get_str - parse a string token
633  * @dest: the buffer to store the string token
634  * @src: the original string
635  * @len: the max. length of token - 1
636  *
637  * Parses the original string and copy a token to the given
638  * string buffer.
639  *
640  * Return: The updated pointer of the original string so that
641  * it can be used for the next call.
642  */
643 const char *snd_info_get_str(char *dest, const char *src, int len)
644 {
645 	int c;
646 
647 	while (*src == ' ' || *src == '\t')
648 		src++;
649 	if (*src == '"' || *src == '\'') {
650 		c = *src++;
651 		while (--len > 0 && *src && *src != c) {
652 			*dest++ = *src++;
653 		}
654 		if (*src == c)
655 			src++;
656 	} else {
657 		while (--len > 0 && *src && *src != ' ' && *src != '\t') {
658 			*dest++ = *src++;
659 		}
660 	}
661 	*dest = 0;
662 	while (*src == ' ' || *src == '\t')
663 		src++;
664 	return src;
665 }
666 EXPORT_SYMBOL(snd_info_get_str);
667 
668 /*
669  * snd_info_create_entry - create an info entry
670  * @name: the proc file name
671  * @parent: the parent directory
672  *
673  * Creates an info entry with the given file name and initializes as
674  * the default state.
675  *
676  * Usually called from other functions such as
677  * snd_info_create_card_entry().
678  *
679  * Return: The pointer of the new instance, or %NULL on failure.
680  */
681 static struct snd_info_entry *
682 snd_info_create_entry(const char *name, struct snd_info_entry *parent,
683 		      struct module *module)
684 {
685 	struct snd_info_entry *entry;
686 	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
687 	if (entry == NULL)
688 		return NULL;
689 	entry->name = kstrdup(name, GFP_KERNEL);
690 	if (entry->name == NULL) {
691 		kfree(entry);
692 		return NULL;
693 	}
694 	entry->mode = S_IFREG | 0444;
695 	entry->content = SNDRV_INFO_CONTENT_TEXT;
696 	mutex_init(&entry->access);
697 	INIT_LIST_HEAD(&entry->children);
698 	INIT_LIST_HEAD(&entry->list);
699 	entry->parent = parent;
700 	entry->module = module;
701 	if (parent) {
702 		mutex_lock(&parent->access);
703 		list_add_tail(&entry->list, &parent->children);
704 		mutex_unlock(&parent->access);
705 	}
706 	return entry;
707 }
708 
709 /**
710  * snd_info_create_module_entry - create an info entry for the given module
711  * @module: the module pointer
712  * @name: the file name
713  * @parent: the parent directory
714  *
715  * Creates a new info entry and assigns it to the given module.
716  *
717  * Return: The pointer of the new instance, or %NULL on failure.
718  */
719 struct snd_info_entry *snd_info_create_module_entry(struct module * module,
720 					       const char *name,
721 					       struct snd_info_entry *parent)
722 {
723 	if (!parent)
724 		parent = snd_proc_root;
725 	return snd_info_create_entry(name, parent, module);
726 }
727 EXPORT_SYMBOL(snd_info_create_module_entry);
728 
729 /**
730  * snd_info_create_card_entry - create an info entry for the given card
731  * @card: the card instance
732  * @name: the file name
733  * @parent: the parent directory
734  *
735  * Creates a new info entry and assigns it to the given card.
736  *
737  * Return: The pointer of the new instance, or %NULL on failure.
738  */
739 struct snd_info_entry *snd_info_create_card_entry(struct snd_card *card,
740 					     const char *name,
741 					     struct snd_info_entry * parent)
742 {
743 	if (!parent)
744 		parent = card->proc_root;
745 	return snd_info_create_entry(name, parent, card->module);
746 }
747 EXPORT_SYMBOL(snd_info_create_card_entry);
748 
749 static void snd_info_disconnect(struct snd_info_entry *entry)
750 {
751 	struct snd_info_entry *p;
752 
753 	if (!entry->p)
754 		return;
755 	list_for_each_entry(p, &entry->children, list)
756 		snd_info_disconnect(p);
757 	proc_remove(entry->p);
758 	entry->p = NULL;
759 }
760 
761 /**
762  * snd_info_free_entry - release the info entry
763  * @entry: the info entry
764  *
765  * Releases the info entry.
766  */
767 void snd_info_free_entry(struct snd_info_entry * entry)
768 {
769 	struct snd_info_entry *p, *n;
770 
771 	if (!entry)
772 		return;
773 	if (entry->p) {
774 		mutex_lock(&info_mutex);
775 		snd_info_disconnect(entry);
776 		mutex_unlock(&info_mutex);
777 	}
778 
779 	/* free all children at first */
780 	list_for_each_entry_safe(p, n, &entry->children, list)
781 		snd_info_free_entry(p);
782 
783 	p = entry->parent;
784 	if (p) {
785 		mutex_lock(&p->access);
786 		list_del(&entry->list);
787 		mutex_unlock(&p->access);
788 	}
789 	kfree(entry->name);
790 	if (entry->private_free)
791 		entry->private_free(entry);
792 	kfree(entry);
793 }
794 EXPORT_SYMBOL(snd_info_free_entry);
795 
796 static int __snd_info_register(struct snd_info_entry *entry)
797 {
798 	struct proc_dir_entry *root, *p = NULL;
799 
800 	if (snd_BUG_ON(!entry))
801 		return -ENXIO;
802 	root = entry->parent == NULL ? snd_proc_root->p : entry->parent->p;
803 	mutex_lock(&info_mutex);
804 	if (entry->p || !root)
805 		goto unlock;
806 	if (S_ISDIR(entry->mode)) {
807 		p = proc_mkdir_mode(entry->name, entry->mode, root);
808 		if (!p) {
809 			mutex_unlock(&info_mutex);
810 			return -ENOMEM;
811 		}
812 	} else {
813 		const struct file_operations *ops;
814 		if (entry->content == SNDRV_INFO_CONTENT_DATA)
815 			ops = &snd_info_entry_operations;
816 		else
817 			ops = &snd_info_text_entry_ops;
818 		p = proc_create_data(entry->name, entry->mode, root,
819 				     ops, entry);
820 		if (!p) {
821 			mutex_unlock(&info_mutex);
822 			return -ENOMEM;
823 		}
824 		proc_set_size(p, entry->size);
825 	}
826 	entry->p = p;
827  unlock:
828 	mutex_unlock(&info_mutex);
829 	return 0;
830 }
831 
832 /**
833  * snd_info_register - register the info entry
834  * @entry: the info entry
835  *
836  * Registers the proc info entry.
837  * The all children entries are registered recursively.
838  *
839  * Return: Zero if successful, or a negative error code on failure.
840  */
841 int snd_info_register(struct snd_info_entry *entry)
842 {
843 	struct snd_info_entry *p;
844 	int err;
845 
846 	if (!entry->p) {
847 		err = __snd_info_register(entry);
848 		if (err < 0)
849 			return err;
850 	}
851 
852 	list_for_each_entry(p, &entry->children, list) {
853 		err = snd_info_register(p);
854 		if (err < 0)
855 			return err;
856 	}
857 
858 	return 0;
859 }
860 EXPORT_SYMBOL(snd_info_register);
861 
862 /**
863  * snd_card_rw_proc_new - Create a read/write text proc file entry for the card
864  * @card: the card instance
865  * @name: the file name
866  * @private_data: the arbitrary private data
867  * @read: the read callback
868  * @write: the write callback, NULL for read-only
869  *
870  * This proc file entry will be registered via snd_card_register() call, and
871  * it will be removed automatically at the card removal, too.
872  */
873 int snd_card_rw_proc_new(struct snd_card *card, const char *name,
874 			 void *private_data,
875 			 void (*read)(struct snd_info_entry *,
876 				      struct snd_info_buffer *),
877 			 void (*write)(struct snd_info_entry *entry,
878 				       struct snd_info_buffer *buffer))
879 {
880 	struct snd_info_entry *entry;
881 
882 	entry = snd_info_create_card_entry(card, name, card->proc_root);
883 	if (!entry)
884 		return -ENOMEM;
885 	snd_info_set_text_ops(entry, private_data, read);
886 	if (write) {
887 		entry->mode |= 0200;
888 		entry->c.text.write = write;
889 	}
890 	return 0;
891 }
892 EXPORT_SYMBOL_GPL(snd_card_rw_proc_new);
893 
894 /*
895 
896  */
897 
898 static void snd_info_version_read(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
899 {
900 	snd_iprintf(buffer,
901 		    "Advanced Linux Sound Architecture Driver Version k%s.\n",
902 		    init_utsname()->release);
903 }
904 
905 static int __init snd_info_version_init(void)
906 {
907 	struct snd_info_entry *entry;
908 
909 	entry = snd_info_create_module_entry(THIS_MODULE, "version", NULL);
910 	if (entry == NULL)
911 		return -ENOMEM;
912 	entry->c.text.read = snd_info_version_read;
913 	return snd_info_register(entry); /* freed in error path */
914 }
915