xref: /openbmc/linux/sound/core/info.c (revision b4e18b29) 
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 const char * const 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 	const char * const *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 proc_ops snd_info_entry_operations =
286 {
287 	.proc_lseek	= snd_info_entry_llseek,
288 	.proc_read	= snd_info_entry_read,
289 	.proc_write	= snd_info_entry_write,
290 	.proc_poll	= snd_info_entry_poll,
291 	.proc_ioctl	= snd_info_entry_ioctl,
292 	.proc_mmap	= snd_info_entry_mmap,
293 	.proc_open	= snd_info_entry_open,
294 	.proc_release	= snd_info_entry_release,
295 };
296 
297 /*
298  * file ops for text proc files
299  */
300 static ssize_t snd_info_text_entry_write(struct file *file,
301 					 const char __user *buffer,
302 					 size_t count, loff_t *offset)
303 {
304 	struct seq_file *m = file->private_data;
305 	struct snd_info_private_data *data = m->private;
306 	struct snd_info_entry *entry = data->entry;
307 	struct snd_info_buffer *buf;
308 	loff_t pos;
309 	size_t next;
310 	int err = 0;
311 
312 	if (!entry->c.text.write)
313 		return -EIO;
314 	pos = *offset;
315 	if (!valid_pos(pos, count))
316 		return -EIO;
317 	next = pos + count;
318 	/* don't handle too large text inputs */
319 	if (next > 16 * 1024)
320 		return -EIO;
321 	mutex_lock(&entry->access);
322 	buf = data->wbuffer;
323 	if (!buf) {
324 		data->wbuffer = buf = kzalloc(sizeof(*buf), GFP_KERNEL);
325 		if (!buf) {
326 			err = -ENOMEM;
327 			goto error;
328 		}
329 	}
330 	if (next > buf->len) {
331 		char *nbuf = kvzalloc(PAGE_ALIGN(next), GFP_KERNEL);
332 		if (!nbuf) {
333 			err = -ENOMEM;
334 			goto error;
335 		}
336 		kvfree(buf->buffer);
337 		buf->buffer = nbuf;
338 		buf->len = PAGE_ALIGN(next);
339 	}
340 	if (copy_from_user(buf->buffer + pos, buffer, count)) {
341 		err = -EFAULT;
342 		goto error;
343 	}
344 	buf->size = next;
345  error:
346 	mutex_unlock(&entry->access);
347 	if (err < 0)
348 		return err;
349 	*offset = next;
350 	return count;
351 }
352 
353 static int snd_info_seq_show(struct seq_file *seq, void *p)
354 {
355 	struct snd_info_private_data *data = seq->private;
356 	struct snd_info_entry *entry = data->entry;
357 
358 	if (!entry->c.text.read) {
359 		return -EIO;
360 	} else {
361 		data->rbuffer->buffer = (char *)seq; /* XXX hack! */
362 		entry->c.text.read(entry, data->rbuffer);
363 	}
364 	return 0;
365 }
366 
367 static int snd_info_text_entry_open(struct inode *inode, struct file *file)
368 {
369 	struct snd_info_entry *entry = PDE_DATA(inode);
370 	struct snd_info_private_data *data;
371 	int err;
372 
373 	mutex_lock(&info_mutex);
374 	err = alloc_info_private(entry, &data);
375 	if (err < 0)
376 		goto unlock;
377 
378 	data->rbuffer = kzalloc(sizeof(*data->rbuffer), GFP_KERNEL);
379 	if (!data->rbuffer) {
380 		err = -ENOMEM;
381 		goto error;
382 	}
383 	if (entry->size)
384 		err = single_open_size(file, snd_info_seq_show, data,
385 				       entry->size);
386 	else
387 		err = single_open(file, snd_info_seq_show, data);
388 	if (err < 0)
389 		goto error;
390 	mutex_unlock(&info_mutex);
391 	return 0;
392 
393  error:
394 	kfree(data->rbuffer);
395 	kfree(data);
396 	module_put(entry->module);
397  unlock:
398 	mutex_unlock(&info_mutex);
399 	return err;
400 }
401 
402 static int snd_info_text_entry_release(struct inode *inode, struct file *file)
403 {
404 	struct seq_file *m = file->private_data;
405 	struct snd_info_private_data *data = m->private;
406 	struct snd_info_entry *entry = data->entry;
407 
408 	if (data->wbuffer && entry->c.text.write)
409 		entry->c.text.write(entry, data->wbuffer);
410 
411 	single_release(inode, file);
412 	kfree(data->rbuffer);
413 	if (data->wbuffer) {
414 		kvfree(data->wbuffer->buffer);
415 		kfree(data->wbuffer);
416 	}
417 
418 	module_put(entry->module);
419 	kfree(data);
420 	return 0;
421 }
422 
423 static const struct proc_ops snd_info_text_entry_ops =
424 {
425 	.proc_open	= snd_info_text_entry_open,
426 	.proc_release	= snd_info_text_entry_release,
427 	.proc_write	= snd_info_text_entry_write,
428 	.proc_lseek	= seq_lseek,
429 	.proc_read	= seq_read,
430 };
431 
432 static struct snd_info_entry *create_subdir(struct module *mod,
433 					    const char *name)
434 {
435 	struct snd_info_entry *entry;
436 
437 	entry = snd_info_create_module_entry(mod, name, NULL);
438 	if (!entry)
439 		return NULL;
440 	entry->mode = S_IFDIR | 0555;
441 	if (snd_info_register(entry) < 0) {
442 		snd_info_free_entry(entry);
443 		return NULL;
444 	}
445 	return entry;
446 }
447 
448 static struct snd_info_entry *
449 snd_info_create_entry(const char *name, struct snd_info_entry *parent,
450 		      struct module *module);
451 
452 int __init snd_info_init(void)
453 {
454 	snd_proc_root = snd_info_create_entry("asound", NULL, THIS_MODULE);
455 	if (!snd_proc_root)
456 		return -ENOMEM;
457 	snd_proc_root->mode = S_IFDIR | 0555;
458 	snd_proc_root->p = proc_mkdir("asound", NULL);
459 	if (!snd_proc_root->p)
460 		goto error;
461 #ifdef CONFIG_SND_OSSEMUL
462 	snd_oss_root = create_subdir(THIS_MODULE, "oss");
463 	if (!snd_oss_root)
464 		goto error;
465 #endif
466 #if IS_ENABLED(CONFIG_SND_SEQUENCER)
467 	snd_seq_root = create_subdir(THIS_MODULE, "seq");
468 	if (!snd_seq_root)
469 		goto error;
470 #endif
471 	if (snd_info_version_init() < 0 ||
472 	    snd_minor_info_init() < 0 ||
473 	    snd_minor_info_oss_init() < 0 ||
474 	    snd_card_info_init() < 0 ||
475 	    snd_info_minor_register() < 0)
476 		goto error;
477 	return 0;
478 
479  error:
480 	snd_info_free_entry(snd_proc_root);
481 	return -ENOMEM;
482 }
483 
484 int __exit snd_info_done(void)
485 {
486 	snd_info_free_entry(snd_proc_root);
487 	return 0;
488 }
489 
490 static void snd_card_id_read(struct snd_info_entry *entry,
491 			     struct snd_info_buffer *buffer)
492 {
493 	struct snd_card *card = entry->private_data;
494 
495 	snd_iprintf(buffer, "%s\n", card->id);
496 }
497 
498 /*
499  * create a card proc file
500  * called from init.c
501  */
502 int snd_info_card_create(struct snd_card *card)
503 {
504 	char str[8];
505 	struct snd_info_entry *entry;
506 
507 	if (snd_BUG_ON(!card))
508 		return -ENXIO;
509 
510 	sprintf(str, "card%i", card->number);
511 	entry = create_subdir(card->module, str);
512 	if (!entry)
513 		return -ENOMEM;
514 	card->proc_root = entry;
515 
516 	return snd_card_ro_proc_new(card, "id", card, snd_card_id_read);
517 }
518 
519 /*
520  * register the card proc file
521  * called from init.c
522  * can be called multiple times for reinitialization
523  */
524 int snd_info_card_register(struct snd_card *card)
525 {
526 	struct proc_dir_entry *p;
527 	int err;
528 
529 	if (snd_BUG_ON(!card))
530 		return -ENXIO;
531 
532 	err = snd_info_register(card->proc_root);
533 	if (err < 0)
534 		return err;
535 
536 	if (!strcmp(card->id, card->proc_root->name))
537 		return 0;
538 
539 	if (card->proc_root_link)
540 		return 0;
541 	p = proc_symlink(card->id, snd_proc_root->p, card->proc_root->name);
542 	if (!p)
543 		return -ENOMEM;
544 	card->proc_root_link = p;
545 	return 0;
546 }
547 
548 /*
549  * called on card->id change
550  */
551 void snd_info_card_id_change(struct snd_card *card)
552 {
553 	mutex_lock(&info_mutex);
554 	if (card->proc_root_link) {
555 		proc_remove(card->proc_root_link);
556 		card->proc_root_link = NULL;
557 	}
558 	if (strcmp(card->id, card->proc_root->name))
559 		card->proc_root_link = proc_symlink(card->id,
560 						    snd_proc_root->p,
561 						    card->proc_root->name);
562 	mutex_unlock(&info_mutex);
563 }
564 
565 /*
566  * de-register the card proc file
567  * called from init.c
568  */
569 void snd_info_card_disconnect(struct snd_card *card)
570 {
571 	if (!card)
572 		return;
573 	mutex_lock(&info_mutex);
574 	proc_remove(card->proc_root_link);
575 	card->proc_root_link = NULL;
576 	if (card->proc_root)
577 		snd_info_disconnect(card->proc_root);
578 	mutex_unlock(&info_mutex);
579 }
580 
581 /*
582  * release the card proc file resources
583  * called from init.c
584  */
585 int snd_info_card_free(struct snd_card *card)
586 {
587 	if (!card)
588 		return 0;
589 	snd_info_free_entry(card->proc_root);
590 	card->proc_root = NULL;
591 	return 0;
592 }
593 
594 
595 /**
596  * snd_info_get_line - read one line from the procfs buffer
597  * @buffer: the procfs buffer
598  * @line: the buffer to store
599  * @len: the max. buffer size
600  *
601  * Reads one line from the buffer and stores the string.
602  *
603  * Return: Zero if successful, or 1 if error or EOF.
604  */
605 int snd_info_get_line(struct snd_info_buffer *buffer, char *line, int len)
606 {
607 	int c;
608 
609 	if (snd_BUG_ON(!buffer))
610 		return 1;
611 	if (!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 proc_ops *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