xref: /openbmc/linux/sound/core/control_led.c (revision 75020f2d)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  LED state routines for driver control interface
4  *  Copyright (c) 2021 by Jaroslav Kysela <perex@perex.cz>
5  */
6 
7 #include <linux/slab.h>
8 #include <linux/module.h>
9 #include <linux/leds.h>
10 #include <sound/core.h>
11 #include <sound/control.h>
12 
13 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
14 MODULE_DESCRIPTION("ALSA control interface to LED trigger code.");
15 MODULE_LICENSE("GPL");
16 
17 #define MAX_LED (((SNDRV_CTL_ELEM_ACCESS_MIC_LED - SNDRV_CTL_ELEM_ACCESS_SPK_LED) \
18 			>> SNDRV_CTL_ELEM_ACCESS_LED_SHIFT) + 1)
19 
20 #define to_led_card_dev(_dev) \
21 	container_of(_dev, struct snd_ctl_led_card, dev)
22 
23 enum snd_ctl_led_mode {
24 	 MODE_FOLLOW_MUTE = 0,
25 	 MODE_FOLLOW_ROUTE,
26 	 MODE_OFF,
27 	 MODE_ON,
28 };
29 
30 struct snd_ctl_led_card {
31 	struct device dev;
32 	int number;
33 	struct snd_ctl_led *led;
34 };
35 
36 struct snd_ctl_led {
37 	struct device dev;
38 	struct list_head controls;
39 	const char *name;
40 	unsigned int group;
41 	enum led_audio trigger_type;
42 	enum snd_ctl_led_mode mode;
43 	struct snd_ctl_led_card *cards[SNDRV_CARDS];
44 };
45 
46 struct snd_ctl_led_ctl {
47 	struct list_head list;
48 	struct snd_card *card;
49 	unsigned int access;
50 	struct snd_kcontrol *kctl;
51 	unsigned int index_offset;
52 };
53 
54 static DEFINE_MUTEX(snd_ctl_led_mutex);
55 static bool snd_ctl_led_card_valid[SNDRV_CARDS];
56 static struct snd_ctl_led snd_ctl_leds[MAX_LED] = {
57 	{
58 		.name = "speaker",
59 		.group = (SNDRV_CTL_ELEM_ACCESS_SPK_LED >> SNDRV_CTL_ELEM_ACCESS_LED_SHIFT) - 1,
60 		.trigger_type = LED_AUDIO_MUTE,
61 		.mode = MODE_FOLLOW_MUTE,
62 	},
63 	{
64 		.name = "mic",
65 		.group = (SNDRV_CTL_ELEM_ACCESS_MIC_LED >> SNDRV_CTL_ELEM_ACCESS_LED_SHIFT) - 1,
66 		.trigger_type = LED_AUDIO_MICMUTE,
67 		.mode = MODE_FOLLOW_MUTE,
68 	},
69 };
70 
71 static void snd_ctl_led_sysfs_add(struct snd_card *card);
72 static void snd_ctl_led_sysfs_remove(struct snd_card *card);
73 
74 #define UPDATE_ROUTE(route, cb) \
75 	do { \
76 		int route2 = (cb); \
77 		if (route2 >= 0) \
78 			route = route < 0 ? route2 : (route | route2); \
79 	} while (0)
80 
81 static inline unsigned int access_to_group(unsigned int access)
82 {
83 	return ((access & SNDRV_CTL_ELEM_ACCESS_LED_MASK) >>
84 				SNDRV_CTL_ELEM_ACCESS_LED_SHIFT) - 1;
85 }
86 
87 static inline unsigned int group_to_access(unsigned int group)
88 {
89 	return (group + 1) << SNDRV_CTL_ELEM_ACCESS_LED_SHIFT;
90 }
91 
92 static struct snd_ctl_led *snd_ctl_led_get_by_access(unsigned int access)
93 {
94 	unsigned int group = access_to_group(access);
95 	if (group >= MAX_LED)
96 		return NULL;
97 	return &snd_ctl_leds[group];
98 }
99 
100 /*
101  * A note for callers:
102  *   The two static variables info and value are protected using snd_ctl_led_mutex.
103  */
104 static int snd_ctl_led_get(struct snd_ctl_led_ctl *lctl)
105 {
106 	static struct snd_ctl_elem_info info;
107 	static struct snd_ctl_elem_value value;
108 	struct snd_kcontrol *kctl = lctl->kctl;
109 	unsigned int i;
110 	int result;
111 
112 	memset(&info, 0, sizeof(info));
113 	info.id = kctl->id;
114 	info.id.index += lctl->index_offset;
115 	info.id.numid += lctl->index_offset;
116 	result = kctl->info(kctl, &info);
117 	if (result < 0)
118 		return -1;
119 	memset(&value, 0, sizeof(value));
120 	value.id = info.id;
121 	result = kctl->get(kctl, &value);
122 	if (result < 0)
123 		return -1;
124 	if (info.type == SNDRV_CTL_ELEM_TYPE_BOOLEAN ||
125 	    info.type == SNDRV_CTL_ELEM_TYPE_INTEGER) {
126 		for (i = 0; i < info.count; i++)
127 			if (value.value.integer.value[i] != info.value.integer.min)
128 				return 1;
129 	} else if (info.type == SNDRV_CTL_ELEM_TYPE_INTEGER64) {
130 		for (i = 0; i < info.count; i++)
131 			if (value.value.integer64.value[i] != info.value.integer64.min)
132 				return 1;
133 	}
134 	return 0;
135 }
136 
137 static void snd_ctl_led_set_state(struct snd_card *card, unsigned int access,
138 				  struct snd_kcontrol *kctl, unsigned int ioff)
139 {
140 	struct snd_ctl_led *led;
141 	struct snd_ctl_led_ctl *lctl;
142 	int route;
143 	bool found;
144 
145 	led = snd_ctl_led_get_by_access(access);
146 	if (!led)
147 		return;
148 	route = -1;
149 	found = false;
150 	mutex_lock(&snd_ctl_led_mutex);
151 	/* the card may not be registered (active) at this point */
152 	if (card && !snd_ctl_led_card_valid[card->number]) {
153 		mutex_unlock(&snd_ctl_led_mutex);
154 		return;
155 	}
156 	list_for_each_entry(lctl, &led->controls, list) {
157 		if (lctl->kctl == kctl && lctl->index_offset == ioff)
158 			found = true;
159 		UPDATE_ROUTE(route, snd_ctl_led_get(lctl));
160 	}
161 	if (!found && kctl && card) {
162 		lctl = kzalloc(sizeof(*lctl), GFP_KERNEL);
163 		if (lctl) {
164 			lctl->card = card;
165 			lctl->access = access;
166 			lctl->kctl = kctl;
167 			lctl->index_offset = ioff;
168 			list_add(&lctl->list, &led->controls);
169 			UPDATE_ROUTE(route, snd_ctl_led_get(lctl));
170 		}
171 	}
172 	mutex_unlock(&snd_ctl_led_mutex);
173 	switch (led->mode) {
174 	case MODE_OFF:		route = 1; break;
175 	case MODE_ON:		route = 0; break;
176 	case MODE_FOLLOW_ROUTE:	if (route >= 0) route ^= 1; break;
177 	case MODE_FOLLOW_MUTE:	/* noop */ break;
178 	}
179 	if (route >= 0)
180 		ledtrig_audio_set(led->trigger_type, route ? LED_OFF : LED_ON);
181 }
182 
183 static struct snd_ctl_led_ctl *snd_ctl_led_find(struct snd_kcontrol *kctl, unsigned int ioff)
184 {
185 	struct list_head *controls;
186 	struct snd_ctl_led_ctl *lctl;
187 	unsigned int group;
188 
189 	for (group = 0; group < MAX_LED; group++) {
190 		controls = &snd_ctl_leds[group].controls;
191 		list_for_each_entry(lctl, controls, list)
192 			if (lctl->kctl == kctl && lctl->index_offset == ioff)
193 				return lctl;
194 	}
195 	return NULL;
196 }
197 
198 static unsigned int snd_ctl_led_remove(struct snd_kcontrol *kctl, unsigned int ioff,
199 				       unsigned int access)
200 {
201 	struct snd_ctl_led_ctl *lctl;
202 	unsigned int ret = 0;
203 
204 	mutex_lock(&snd_ctl_led_mutex);
205 	lctl = snd_ctl_led_find(kctl, ioff);
206 	if (lctl && (access == 0 || access != lctl->access)) {
207 		ret = lctl->access;
208 		list_del(&lctl->list);
209 		kfree(lctl);
210 	}
211 	mutex_unlock(&snd_ctl_led_mutex);
212 	return ret;
213 }
214 
215 static void snd_ctl_led_notify(struct snd_card *card, unsigned int mask,
216 			       struct snd_kcontrol *kctl, unsigned int ioff)
217 {
218 	struct snd_kcontrol_volatile *vd;
219 	unsigned int access, access2;
220 
221 	if (mask == SNDRV_CTL_EVENT_MASK_REMOVE) {
222 		access = snd_ctl_led_remove(kctl, ioff, 0);
223 		if (access)
224 			snd_ctl_led_set_state(card, access, NULL, 0);
225 	} else if (mask & SNDRV_CTL_EVENT_MASK_INFO) {
226 		vd = &kctl->vd[ioff];
227 		access = vd->access & SNDRV_CTL_ELEM_ACCESS_LED_MASK;
228 		access2 = snd_ctl_led_remove(kctl, ioff, access);
229 		if (access2)
230 			snd_ctl_led_set_state(card, access2, NULL, 0);
231 		if (access)
232 			snd_ctl_led_set_state(card, access, kctl, ioff);
233 	} else if ((mask & (SNDRV_CTL_EVENT_MASK_ADD |
234 			    SNDRV_CTL_EVENT_MASK_VALUE)) != 0) {
235 		vd = &kctl->vd[ioff];
236 		access = vd->access & SNDRV_CTL_ELEM_ACCESS_LED_MASK;
237 		if (access)
238 			snd_ctl_led_set_state(card, access, kctl, ioff);
239 	}
240 }
241 
242 static int snd_ctl_led_set_id(int card_number, struct snd_ctl_elem_id *id,
243 			      unsigned int group, bool set)
244 {
245 	struct snd_card *card;
246 	struct snd_kcontrol *kctl;
247 	struct snd_kcontrol_volatile *vd;
248 	unsigned int ioff, access, new_access;
249 	int err = 0;
250 
251 	card = snd_card_ref(card_number);
252 	if (card) {
253 		down_write(&card->controls_rwsem);
254 		kctl = snd_ctl_find_id(card, id);
255 		if (kctl) {
256 			ioff = snd_ctl_get_ioff(kctl, id);
257 			vd = &kctl->vd[ioff];
258 			access = vd->access & SNDRV_CTL_ELEM_ACCESS_LED_MASK;
259 			if (access != 0 && access != group_to_access(group)) {
260 				err = -EXDEV;
261 				goto unlock;
262 			}
263 			new_access = vd->access & ~SNDRV_CTL_ELEM_ACCESS_LED_MASK;
264 			if (set)
265 				new_access |= group_to_access(group);
266 			if (new_access != vd->access) {
267 				vd->access = new_access;
268 				snd_ctl_led_notify(card, SNDRV_CTL_EVENT_MASK_INFO, kctl, ioff);
269 			}
270 		} else {
271 			err = -ENOENT;
272 		}
273 unlock:
274 		up_write(&card->controls_rwsem);
275 		snd_card_unref(card);
276 	} else {
277 		err = -ENXIO;
278 	}
279 	return err;
280 }
281 
282 static void snd_ctl_led_refresh(void)
283 {
284 	unsigned int group;
285 
286 	for (group = 0; group < MAX_LED; group++)
287 		snd_ctl_led_set_state(NULL, group_to_access(group), NULL, 0);
288 }
289 
290 static void snd_ctl_led_ctl_destroy(struct snd_ctl_led_ctl *lctl)
291 {
292 	list_del(&lctl->list);
293 	kfree(lctl);
294 }
295 
296 static void snd_ctl_led_clean(struct snd_card *card)
297 {
298 	unsigned int group;
299 	struct snd_ctl_led *led;
300 	struct snd_ctl_led_ctl *lctl;
301 
302 	for (group = 0; group < MAX_LED; group++) {
303 		led = &snd_ctl_leds[group];
304 repeat:
305 		list_for_each_entry(lctl, &led->controls, list)
306 			if (!card || lctl->card == card) {
307 				snd_ctl_led_ctl_destroy(lctl);
308 				goto repeat;
309 			}
310 	}
311 }
312 
313 static int snd_ctl_led_reset(int card_number, unsigned int group)
314 {
315 	struct snd_card *card;
316 	struct snd_ctl_led *led;
317 	struct snd_ctl_led_ctl *lctl;
318 	struct snd_kcontrol_volatile *vd;
319 	bool change = false;
320 
321 	card = snd_card_ref(card_number);
322 	if (!card)
323 		return -ENXIO;
324 
325 	mutex_lock(&snd_ctl_led_mutex);
326 	if (!snd_ctl_led_card_valid[card_number]) {
327 		mutex_unlock(&snd_ctl_led_mutex);
328 		snd_card_unref(card);
329 		return -ENXIO;
330 	}
331 	led = &snd_ctl_leds[group];
332 repeat:
333 	list_for_each_entry(lctl, &led->controls, list)
334 		if (lctl->card == card) {
335 			vd = &lctl->kctl->vd[lctl->index_offset];
336 			vd->access &= ~group_to_access(group);
337 			snd_ctl_led_ctl_destroy(lctl);
338 			change = true;
339 			goto repeat;
340 		}
341 	mutex_unlock(&snd_ctl_led_mutex);
342 	if (change)
343 		snd_ctl_led_set_state(NULL, group_to_access(group), NULL, 0);
344 	snd_card_unref(card);
345 	return 0;
346 }
347 
348 static void snd_ctl_led_register(struct snd_card *card)
349 {
350 	struct snd_kcontrol *kctl;
351 	unsigned int ioff;
352 
353 	if (snd_BUG_ON(card->number < 0 ||
354 		       card->number >= ARRAY_SIZE(snd_ctl_led_card_valid)))
355 		return;
356 	mutex_lock(&snd_ctl_led_mutex);
357 	snd_ctl_led_card_valid[card->number] = true;
358 	mutex_unlock(&snd_ctl_led_mutex);
359 	/* the register callback is already called with held card->controls_rwsem */
360 	list_for_each_entry(kctl, &card->controls, list)
361 		for (ioff = 0; ioff < kctl->count; ioff++)
362 			snd_ctl_led_notify(card, SNDRV_CTL_EVENT_MASK_VALUE, kctl, ioff);
363 	snd_ctl_led_refresh();
364 	snd_ctl_led_sysfs_add(card);
365 }
366 
367 static void snd_ctl_led_disconnect(struct snd_card *card)
368 {
369 	snd_ctl_led_sysfs_remove(card);
370 	mutex_lock(&snd_ctl_led_mutex);
371 	snd_ctl_led_card_valid[card->number] = false;
372 	snd_ctl_led_clean(card);
373 	mutex_unlock(&snd_ctl_led_mutex);
374 	snd_ctl_led_refresh();
375 }
376 
377 static void snd_ctl_led_card_release(struct device *dev)
378 {
379 	struct snd_ctl_led_card *led_card = to_led_card_dev(dev);
380 
381 	kfree(led_card);
382 }
383 
384 static void snd_ctl_led_release(struct device *dev)
385 {
386 }
387 
388 static void snd_ctl_led_dev_release(struct device *dev)
389 {
390 }
391 
392 /*
393  * sysfs
394  */
395 
396 static ssize_t show_mode(struct device *dev,
397 			 struct device_attribute *attr, char *buf)
398 {
399 	struct snd_ctl_led *led = container_of(dev, struct snd_ctl_led, dev);
400 	const char *str;
401 
402 	switch (led->mode) {
403 	case MODE_FOLLOW_MUTE:	str = "follow-mute"; break;
404 	case MODE_FOLLOW_ROUTE:	str = "follow-route"; break;
405 	case MODE_ON:		str = "on"; break;
406 	case MODE_OFF:		str = "off"; break;
407 	}
408 	return sprintf(buf, "%s\n", str);
409 }
410 
411 static ssize_t store_mode(struct device *dev, struct device_attribute *attr,
412 			  const char *buf, size_t count)
413 {
414 	struct snd_ctl_led *led = container_of(dev, struct snd_ctl_led, dev);
415 	char _buf[16];
416 	size_t l = min(count, sizeof(_buf) - 1);
417 	enum snd_ctl_led_mode mode;
418 
419 	memcpy(_buf, buf, l);
420 	_buf[l] = '\0';
421 	if (strstr(_buf, "mute"))
422 		mode = MODE_FOLLOW_MUTE;
423 	else if (strstr(_buf, "route"))
424 		mode = MODE_FOLLOW_ROUTE;
425 	else if (strncmp(_buf, "off", 3) == 0 || strncmp(_buf, "0", 1) == 0)
426 		mode = MODE_OFF;
427 	else if (strncmp(_buf, "on", 2) == 0 || strncmp(_buf, "1", 1) == 0)
428 		mode = MODE_ON;
429 	else
430 		return count;
431 
432 	mutex_lock(&snd_ctl_led_mutex);
433 	led->mode = mode;
434 	mutex_unlock(&snd_ctl_led_mutex);
435 
436 	snd_ctl_led_set_state(NULL, group_to_access(led->group), NULL, 0);
437 	return count;
438 }
439 
440 static ssize_t show_brightness(struct device *dev,
441 			       struct device_attribute *attr, char *buf)
442 {
443 	struct snd_ctl_led *led = container_of(dev, struct snd_ctl_led, dev);
444 
445 	return sprintf(buf, "%u\n", ledtrig_audio_get(led->trigger_type));
446 }
447 
448 static DEVICE_ATTR(mode, 0644, show_mode, store_mode);
449 static DEVICE_ATTR(brightness, 0444, show_brightness, NULL);
450 
451 static struct attribute *snd_ctl_led_dev_attrs[] = {
452 	&dev_attr_mode.attr,
453 	&dev_attr_brightness.attr,
454 	NULL,
455 };
456 
457 static const struct attribute_group snd_ctl_led_dev_attr_group = {
458 	.attrs = snd_ctl_led_dev_attrs,
459 };
460 
461 static const struct attribute_group *snd_ctl_led_dev_attr_groups[] = {
462 	&snd_ctl_led_dev_attr_group,
463 	NULL,
464 };
465 
466 static char *find_eos(char *s)
467 {
468 	while (*s && *s != ',')
469 		s++;
470 	if (*s)
471 		s++;
472 	return s;
473 }
474 
475 static char *parse_uint(char *s, unsigned int *val)
476 {
477 	unsigned long long res;
478 	if (kstrtoull(s, 10, &res))
479 		res = 0;
480 	*val = res;
481 	return find_eos(s);
482 }
483 
484 static char *parse_string(char *s, char *val, size_t val_size)
485 {
486 	if (*s == '"' || *s == '\'') {
487 		char c = *s;
488 		s++;
489 		while (*s && *s != c) {
490 			if (val_size > 1) {
491 				*val++ = *s;
492 				val_size--;
493 			}
494 			s++;
495 		}
496 	} else {
497 		while (*s && *s != ',') {
498 			if (val_size > 1) {
499 				*val++ = *s;
500 				val_size--;
501 			}
502 			s++;
503 		}
504 	}
505 	*val = '\0';
506 	if (*s)
507 		s++;
508 	return s;
509 }
510 
511 static char *parse_iface(char *s, unsigned int *val)
512 {
513 	if (!strncasecmp(s, "card", 4))
514 		*val = SNDRV_CTL_ELEM_IFACE_CARD;
515 	else if (!strncasecmp(s, "mixer", 5))
516 		*val = SNDRV_CTL_ELEM_IFACE_MIXER;
517 	return find_eos(s);
518 }
519 
520 /*
521  * These types of input strings are accepted:
522  *
523  *   unsigned integer - numid (equivaled to numid=UINT)
524  *   string - basic mixer name (equivalent to iface=MIXER,name=STR)
525  *   numid=UINT
526  *   [iface=MIXER,][device=UINT,][subdevice=UINT,]name=STR[,index=UINT]
527  */
528 static ssize_t set_led_id(struct snd_ctl_led_card *led_card, const char *buf, size_t count,
529 			  bool attach)
530 {
531 	char buf2[256], *s, *os;
532 	size_t len = max(sizeof(s) - 1, count);
533 	struct snd_ctl_elem_id id;
534 	int err;
535 
536 	strncpy(buf2, buf, len);
537 	buf2[len] = '\0';
538 	memset(&id, 0, sizeof(id));
539 	id.iface = SNDRV_CTL_ELEM_IFACE_MIXER;
540 	s = buf2;
541 	while (*s) {
542 		os = s;
543 		if (!strncasecmp(s, "numid=", 6)) {
544 			s = parse_uint(s + 6, &id.numid);
545 		} else if (!strncasecmp(s, "iface=", 6)) {
546 			s = parse_iface(s + 6, &id.iface);
547 		} else if (!strncasecmp(s, "device=", 7)) {
548 			s = parse_uint(s + 7, &id.device);
549 		} else if (!strncasecmp(s, "subdevice=", 10)) {
550 			s = parse_uint(s + 10, &id.subdevice);
551 		} else if (!strncasecmp(s, "name=", 5)) {
552 			s = parse_string(s + 5, id.name, sizeof(id.name));
553 		} else if (!strncasecmp(s, "index=", 6)) {
554 			s = parse_uint(s + 6, &id.index);
555 		} else if (s == buf2) {
556 			while (*s) {
557 				if (*s < '0' || *s > '9')
558 					break;
559 				s++;
560 			}
561 			if (*s == '\0')
562 				parse_uint(buf2, &id.numid);
563 			else {
564 				for (; *s >= ' '; s++);
565 				*s = '\0';
566 				strlcpy(id.name, buf2, sizeof(id.name));
567 			}
568 			break;
569 		}
570 		if (*s == ',')
571 			s++;
572 		if (s == os)
573 			break;
574 	}
575 
576 	err = snd_ctl_led_set_id(led_card->number, &id, led_card->led->group, attach);
577 	if (err < 0)
578 		return err;
579 
580 	return count;
581 }
582 
583 static ssize_t parse_attach(struct device *dev, struct device_attribute *attr,
584 			    const char *buf, size_t count)
585 {
586 	struct snd_ctl_led_card *led_card = container_of(dev, struct snd_ctl_led_card, dev);
587 	return set_led_id(led_card, buf, count, true);
588 }
589 
590 static ssize_t parse_detach(struct device *dev, struct device_attribute *attr,
591 			    const char *buf, size_t count)
592 {
593 	struct snd_ctl_led_card *led_card = container_of(dev, struct snd_ctl_led_card, dev);
594 	return set_led_id(led_card, buf, count, false);
595 }
596 
597 static ssize_t ctl_reset(struct device *dev, struct device_attribute *attr,
598 			 const char *buf, size_t count)
599 {
600 	struct snd_ctl_led_card *led_card = container_of(dev, struct snd_ctl_led_card, dev);
601 	int err;
602 
603 	if (count > 0 && buf[0] == '1') {
604 		err = snd_ctl_led_reset(led_card->number, led_card->led->group);
605 		if (err < 0)
606 			return err;
607 	}
608 	return count;
609 }
610 
611 static ssize_t ctl_list(struct device *dev,
612 			struct device_attribute *attr, char *buf)
613 {
614 	struct snd_ctl_led_card *led_card = container_of(dev, struct snd_ctl_led_card, dev);
615 	struct snd_card *card;
616 	struct snd_ctl_led_ctl *lctl;
617 	char *buf2 = buf;
618 	size_t l;
619 
620 	card = snd_card_ref(led_card->number);
621 	if (!card)
622 		return -ENXIO;
623 	down_read(&card->controls_rwsem);
624 	mutex_lock(&snd_ctl_led_mutex);
625 	if (snd_ctl_led_card_valid[led_card->number]) {
626 		list_for_each_entry(lctl, &led_card->led->controls, list)
627 			if (lctl->card == card) {
628 				if (buf2 - buf > PAGE_SIZE - 16)
629 					break;
630 				if (buf2 != buf)
631 					*buf2++ = ' ';
632 				l = scnprintf(buf2, 15, "%u",
633 						lctl->kctl->id.numid +
634 							lctl->index_offset);
635 				buf2[l] = '\0';
636 				buf2 += l + 1;
637 			}
638 	}
639 	mutex_unlock(&snd_ctl_led_mutex);
640 	up_read(&card->controls_rwsem);
641 	snd_card_unref(card);
642 	return buf2 - buf;
643 }
644 
645 static DEVICE_ATTR(attach, 0200, NULL, parse_attach);
646 static DEVICE_ATTR(detach, 0200, NULL, parse_detach);
647 static DEVICE_ATTR(reset, 0200, NULL, ctl_reset);
648 static DEVICE_ATTR(list, 0444, ctl_list, NULL);
649 
650 static struct attribute *snd_ctl_led_card_attrs[] = {
651 	&dev_attr_attach.attr,
652 	&dev_attr_detach.attr,
653 	&dev_attr_reset.attr,
654 	&dev_attr_list.attr,
655 	NULL,
656 };
657 
658 static const struct attribute_group snd_ctl_led_card_attr_group = {
659 	.attrs = snd_ctl_led_card_attrs,
660 };
661 
662 static const struct attribute_group *snd_ctl_led_card_attr_groups[] = {
663 	&snd_ctl_led_card_attr_group,
664 	NULL,
665 };
666 
667 static struct device snd_ctl_led_dev;
668 
669 static void snd_ctl_led_sysfs_add(struct snd_card *card)
670 {
671 	unsigned int group;
672 	struct snd_ctl_led_card *led_card;
673 	struct snd_ctl_led *led;
674 	char link_name[32];
675 
676 	for (group = 0; group < MAX_LED; group++) {
677 		led = &snd_ctl_leds[group];
678 		led_card = kzalloc(sizeof(*led_card), GFP_KERNEL);
679 		if (!led_card)
680 			goto cerr2;
681 		led_card->number = card->number;
682 		led_card->led = led;
683 		device_initialize(&led_card->dev);
684 		led_card->dev.release = snd_ctl_led_card_release;
685 		if (dev_set_name(&led_card->dev, "card%d", card->number) < 0)
686 			goto cerr;
687 		led_card->dev.parent = &led->dev;
688 		led_card->dev.groups = snd_ctl_led_card_attr_groups;
689 		if (device_add(&led_card->dev))
690 			goto cerr;
691 		led->cards[card->number] = led_card;
692 		snprintf(link_name, sizeof(link_name), "led-%s", led->name);
693 		WARN(sysfs_create_link(&card->ctl_dev.kobj, &led_card->dev.kobj, link_name),
694 			"can't create symlink to controlC%i device\n", card->number);
695 		WARN(sysfs_create_link(&led_card->dev.kobj, &card->card_dev.kobj, "card"),
696 			"can't create symlink to card%i\n", card->number);
697 
698 		continue;
699 cerr:
700 		put_device(&led_card->dev);
701 cerr2:
702 		printk(KERN_ERR "snd_ctl_led: unable to add card%d", card->number);
703 	}
704 }
705 
706 static void snd_ctl_led_sysfs_remove(struct snd_card *card)
707 {
708 	unsigned int group;
709 	struct snd_ctl_led_card *led_card;
710 	struct snd_ctl_led *led;
711 	char link_name[32];
712 
713 	for (group = 0; group < MAX_LED; group++) {
714 		led = &snd_ctl_leds[group];
715 		led_card = led->cards[card->number];
716 		if (!led_card)
717 			continue;
718 		snprintf(link_name, sizeof(link_name), "led-%s", led->name);
719 		sysfs_remove_link(&card->ctl_dev.kobj, link_name);
720 		sysfs_remove_link(&led_card->dev.kobj, "card");
721 		device_unregister(&led_card->dev);
722 		led->cards[card->number] = NULL;
723 	}
724 }
725 
726 /*
727  * Control layer registration
728  */
729 static struct snd_ctl_layer_ops snd_ctl_led_lops = {
730 	.module_name = SND_CTL_LAYER_MODULE_LED,
731 	.lregister = snd_ctl_led_register,
732 	.ldisconnect = snd_ctl_led_disconnect,
733 	.lnotify = snd_ctl_led_notify,
734 };
735 
736 static int __init snd_ctl_led_init(void)
737 {
738 	struct snd_ctl_led *led;
739 	unsigned int group;
740 
741 	device_initialize(&snd_ctl_led_dev);
742 	snd_ctl_led_dev.class = sound_class;
743 	snd_ctl_led_dev.release = snd_ctl_led_dev_release;
744 	dev_set_name(&snd_ctl_led_dev, "ctl-led");
745 	if (device_add(&snd_ctl_led_dev)) {
746 		put_device(&snd_ctl_led_dev);
747 		return -ENOMEM;
748 	}
749 	for (group = 0; group < MAX_LED; group++) {
750 		led = &snd_ctl_leds[group];
751 		INIT_LIST_HEAD(&led->controls);
752 		device_initialize(&led->dev);
753 		led->dev.parent = &snd_ctl_led_dev;
754 		led->dev.release = snd_ctl_led_release;
755 		led->dev.groups = snd_ctl_led_dev_attr_groups;
756 		dev_set_name(&led->dev, led->name);
757 		if (device_add(&led->dev)) {
758 			put_device(&led->dev);
759 			for (; group > 0; group--) {
760 				led = &snd_ctl_leds[group - 1];
761 				device_unregister(&led->dev);
762 			}
763 			device_unregister(&snd_ctl_led_dev);
764 			return -ENOMEM;
765 		}
766 	}
767 	snd_ctl_register_layer(&snd_ctl_led_lops);
768 	return 0;
769 }
770 
771 static void __exit snd_ctl_led_exit(void)
772 {
773 	struct snd_ctl_led *led;
774 	struct snd_card *card;
775 	unsigned int group, card_number;
776 
777 	snd_ctl_disconnect_layer(&snd_ctl_led_lops);
778 	for (card_number = 0; card_number < SNDRV_CARDS; card_number++) {
779 		if (!snd_ctl_led_card_valid[card_number])
780 			continue;
781 		card = snd_card_ref(card_number);
782 		if (card) {
783 			snd_ctl_led_sysfs_remove(card);
784 			snd_card_unref(card);
785 		}
786 	}
787 	for (group = 0; group < MAX_LED; group++) {
788 		led = &snd_ctl_leds[group];
789 		device_unregister(&led->dev);
790 	}
791 	device_unregister(&snd_ctl_led_dev);
792 	snd_ctl_led_clean(NULL);
793 }
794 
795 module_init(snd_ctl_led_init)
796 module_exit(snd_ctl_led_exit)
797