xref: /openbmc/linux/sound/core/sound.c (revision 015d239a) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  Advanced Linux Sound Architecture
4  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
5  */
6 
7 #include <linux/init.h>
8 #include <linux/slab.h>
9 #include <linux/time.h>
10 #include <linux/device.h>
11 #include <linux/module.h>
12 #include <sound/core.h>
13 #include <sound/minors.h>
14 #include <sound/info.h>
15 #include <sound/control.h>
16 #include <sound/initval.h>
17 #include <linux/kmod.h>
18 #include <linux/mutex.h>
19 
20 static int major = CONFIG_SND_MAJOR;
21 int snd_major;
22 EXPORT_SYMBOL(snd_major);
23 
24 static int cards_limit = 1;
25 
26 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
27 MODULE_DESCRIPTION("Advanced Linux Sound Architecture driver for soundcards.");
28 MODULE_LICENSE("GPL");
29 module_param(major, int, 0444);
30 MODULE_PARM_DESC(major, "Major # for sound driver.");
31 module_param(cards_limit, int, 0444);
32 MODULE_PARM_DESC(cards_limit, "Count of auto-loadable soundcards.");
33 MODULE_ALIAS_CHARDEV_MAJOR(CONFIG_SND_MAJOR);
34 
35 /* this one holds the actual max. card number currently available.
36  * as default, it's identical with cards_limit option.  when more
37  * modules are loaded manually, this limit number increases, too.
38  */
39 int snd_ecards_limit;
40 EXPORT_SYMBOL(snd_ecards_limit);
41 
42 static struct snd_minor *snd_minors[SNDRV_OS_MINORS];
43 static DEFINE_MUTEX(sound_mutex);
44 
45 #ifdef CONFIG_MODULES
46 
47 /**
48  * snd_request_card - try to load the card module
49  * @card: the card number
50  *
51  * Tries to load the module "snd-card-X" for the given card number
52  * via request_module.  Returns immediately if already loaded.
53  */
54 void snd_request_card(int card)
55 {
56 	if (snd_card_locked(card))
57 		return;
58 	if (card < 0 || card >= cards_limit)
59 		return;
60 	request_module("snd-card-%i", card);
61 }
62 EXPORT_SYMBOL(snd_request_card);
63 
64 static void snd_request_other(int minor)
65 {
66 	char *str;
67 
68 	switch (minor) {
69 	case SNDRV_MINOR_SEQUENCER:	str = "snd-seq";	break;
70 	case SNDRV_MINOR_TIMER:		str = "snd-timer";	break;
71 	default:			return;
72 	}
73 	request_module(str);
74 }
75 
76 #endif	/* modular kernel */
77 
78 /**
79  * snd_lookup_minor_data - get user data of a registered device
80  * @minor: the minor number
81  * @type: device type (SNDRV_DEVICE_TYPE_XXX)
82  *
83  * Checks that a minor device with the specified type is registered, and returns
84  * its user data pointer.
85  *
86  * This function increments the reference counter of the card instance
87  * if an associated instance with the given minor number and type is found.
88  * The caller must call snd_card_unref() appropriately later.
89  *
90  * Return: The user data pointer if the specified device is found. %NULL
91  * otherwise.
92  */
93 void *snd_lookup_minor_data(unsigned int minor, int type)
94 {
95 	struct snd_minor *mreg;
96 	void *private_data;
97 
98 	if (minor >= ARRAY_SIZE(snd_minors))
99 		return NULL;
100 	mutex_lock(&sound_mutex);
101 	mreg = snd_minors[minor];
102 	if (mreg && mreg->type == type) {
103 		private_data = mreg->private_data;
104 		if (private_data && mreg->card_ptr)
105 			get_device(&mreg->card_ptr->card_dev);
106 	} else
107 		private_data = NULL;
108 	mutex_unlock(&sound_mutex);
109 	return private_data;
110 }
111 EXPORT_SYMBOL(snd_lookup_minor_data);
112 
113 #ifdef CONFIG_MODULES
114 static struct snd_minor *autoload_device(unsigned int minor)
115 {
116 	int dev;
117 	mutex_unlock(&sound_mutex); /* release lock temporarily */
118 	dev = SNDRV_MINOR_DEVICE(minor);
119 	if (dev == SNDRV_MINOR_CONTROL) {
120 		/* /dev/aloadC? */
121 		int card = SNDRV_MINOR_CARD(minor);
122 		struct snd_card *ref = snd_card_ref(card);
123 		if (!ref)
124 			snd_request_card(card);
125 		else
126 			snd_card_unref(ref);
127 	} else if (dev == SNDRV_MINOR_GLOBAL) {
128 		/* /dev/aloadSEQ */
129 		snd_request_other(minor);
130 	}
131 	mutex_lock(&sound_mutex); /* reacuire lock */
132 	return snd_minors[minor];
133 }
134 #else /* !CONFIG_MODULES */
135 #define autoload_device(minor)	NULL
136 #endif /* CONFIG_MODULES */
137 
138 static int snd_open(struct inode *inode, struct file *file)
139 {
140 	unsigned int minor = iminor(inode);
141 	struct snd_minor *mptr = NULL;
142 	const struct file_operations *new_fops;
143 	int err = 0;
144 
145 	if (minor >= ARRAY_SIZE(snd_minors))
146 		return -ENODEV;
147 	mutex_lock(&sound_mutex);
148 	mptr = snd_minors[minor];
149 	if (mptr == NULL) {
150 		mptr = autoload_device(minor);
151 		if (!mptr) {
152 			mutex_unlock(&sound_mutex);
153 			return -ENODEV;
154 		}
155 	}
156 	new_fops = fops_get(mptr->f_ops);
157 	mutex_unlock(&sound_mutex);
158 	if (!new_fops)
159 		return -ENODEV;
160 	replace_fops(file, new_fops);
161 
162 	if (file->f_op->open)
163 		err = file->f_op->open(inode, file);
164 	return err;
165 }
166 
167 static const struct file_operations snd_fops =
168 {
169 	.owner =	THIS_MODULE,
170 	.open =		snd_open,
171 	.llseek =	noop_llseek,
172 };
173 
174 #ifdef CONFIG_SND_DYNAMIC_MINORS
175 static int snd_find_free_minor(int type, struct snd_card *card, int dev)
176 {
177 	int minor;
178 
179 	/* static minors for module auto loading */
180 	if (type == SNDRV_DEVICE_TYPE_SEQUENCER)
181 		return SNDRV_MINOR_SEQUENCER;
182 	if (type == SNDRV_DEVICE_TYPE_TIMER)
183 		return SNDRV_MINOR_TIMER;
184 
185 	for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor) {
186 		/* skip static minors still used for module auto loading */
187 		if (SNDRV_MINOR_DEVICE(minor) == SNDRV_MINOR_CONTROL)
188 			continue;
189 		if (minor == SNDRV_MINOR_SEQUENCER ||
190 		    minor == SNDRV_MINOR_TIMER)
191 			continue;
192 		if (!snd_minors[minor])
193 			return minor;
194 	}
195 	return -EBUSY;
196 }
197 #else
198 static int snd_find_free_minor(int type, struct snd_card *card, int dev)
199 {
200 	int minor;
201 
202 	switch (type) {
203 	case SNDRV_DEVICE_TYPE_SEQUENCER:
204 	case SNDRV_DEVICE_TYPE_TIMER:
205 		minor = type;
206 		break;
207 	case SNDRV_DEVICE_TYPE_CONTROL:
208 		if (snd_BUG_ON(!card))
209 			return -EINVAL;
210 		minor = SNDRV_MINOR(card->number, type);
211 		break;
212 	case SNDRV_DEVICE_TYPE_HWDEP:
213 	case SNDRV_DEVICE_TYPE_RAWMIDI:
214 	case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
215 	case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
216 	case SNDRV_DEVICE_TYPE_COMPRESS:
217 		if (snd_BUG_ON(!card))
218 			return -EINVAL;
219 		minor = SNDRV_MINOR(card->number, type + dev);
220 		break;
221 	default:
222 		return -EINVAL;
223 	}
224 	if (snd_BUG_ON(minor < 0 || minor >= SNDRV_OS_MINORS))
225 		return -EINVAL;
226 	if (snd_minors[minor])
227 		return -EBUSY;
228 	return minor;
229 }
230 #endif
231 
232 /**
233  * snd_register_device - Register the ALSA device file for the card
234  * @type: the device type, SNDRV_DEVICE_TYPE_XXX
235  * @card: the card instance
236  * @dev: the device index
237  * @f_ops: the file operations
238  * @private_data: user pointer for f_ops->open()
239  * @device: the device to register
240  *
241  * Registers an ALSA device file for the given card.
242  * The operators have to be set in reg parameter.
243  *
244  * Return: Zero if successful, or a negative error code on failure.
245  */
246 int snd_register_device(int type, struct snd_card *card, int dev,
247 			const struct file_operations *f_ops,
248 			void *private_data, struct device *device)
249 {
250 	int minor;
251 	int err = 0;
252 	struct snd_minor *preg;
253 
254 	if (snd_BUG_ON(!device))
255 		return -EINVAL;
256 
257 	preg = kmalloc(sizeof *preg, GFP_KERNEL);
258 	if (preg == NULL)
259 		return -ENOMEM;
260 	preg->type = type;
261 	preg->card = card ? card->number : -1;
262 	preg->device = dev;
263 	preg->f_ops = f_ops;
264 	preg->private_data = private_data;
265 	preg->card_ptr = card;
266 	mutex_lock(&sound_mutex);
267 	minor = snd_find_free_minor(type, card, dev);
268 	if (minor < 0) {
269 		err = minor;
270 		goto error;
271 	}
272 
273 	preg->dev = device;
274 	device->devt = MKDEV(major, minor);
275 	err = device_add(device);
276 	if (err < 0)
277 		goto error;
278 
279 	snd_minors[minor] = preg;
280  error:
281 	mutex_unlock(&sound_mutex);
282 	if (err < 0)
283 		kfree(preg);
284 	return err;
285 }
286 EXPORT_SYMBOL(snd_register_device);
287 
288 /**
289  * snd_unregister_device - unregister the device on the given card
290  * @dev: the device instance
291  *
292  * Unregisters the device file already registered via
293  * snd_register_device().
294  *
295  * Return: Zero if successful, or a negative error code on failure.
296  */
297 int snd_unregister_device(struct device *dev)
298 {
299 	int minor;
300 	struct snd_minor *preg;
301 
302 	mutex_lock(&sound_mutex);
303 	for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor) {
304 		preg = snd_minors[minor];
305 		if (preg && preg->dev == dev) {
306 			snd_minors[minor] = NULL;
307 			device_del(dev);
308 			kfree(preg);
309 			break;
310 		}
311 	}
312 	mutex_unlock(&sound_mutex);
313 	if (minor >= ARRAY_SIZE(snd_minors))
314 		return -ENOENT;
315 	return 0;
316 }
317 EXPORT_SYMBOL(snd_unregister_device);
318 
319 #ifdef CONFIG_SND_PROC_FS
320 /*
321  *  INFO PART
322  */
323 static const char *snd_device_type_name(int type)
324 {
325 	switch (type) {
326 	case SNDRV_DEVICE_TYPE_CONTROL:
327 		return "control";
328 	case SNDRV_DEVICE_TYPE_HWDEP:
329 		return "hardware dependent";
330 	case SNDRV_DEVICE_TYPE_RAWMIDI:
331 		return "raw midi";
332 	case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
333 		return "digital audio playback";
334 	case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
335 		return "digital audio capture";
336 	case SNDRV_DEVICE_TYPE_SEQUENCER:
337 		return "sequencer";
338 	case SNDRV_DEVICE_TYPE_TIMER:
339 		return "timer";
340 	default:
341 		return "?";
342 	}
343 }
344 
345 static void snd_minor_info_read(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
346 {
347 	int minor;
348 	struct snd_minor *mptr;
349 
350 	mutex_lock(&sound_mutex);
351 	for (minor = 0; minor < SNDRV_OS_MINORS; ++minor) {
352 		if (!(mptr = snd_minors[minor]))
353 			continue;
354 		if (mptr->card >= 0) {
355 			if (mptr->device >= 0)
356 				snd_iprintf(buffer, "%3i: [%2i-%2i]: %s\n",
357 					    minor, mptr->card, mptr->device,
358 					    snd_device_type_name(mptr->type));
359 			else
360 				snd_iprintf(buffer, "%3i: [%2i]   : %s\n",
361 					    minor, mptr->card,
362 					    snd_device_type_name(mptr->type));
363 		} else
364 			snd_iprintf(buffer, "%3i:        : %s\n", minor,
365 				    snd_device_type_name(mptr->type));
366 	}
367 	mutex_unlock(&sound_mutex);
368 }
369 
370 int __init snd_minor_info_init(void)
371 {
372 	struct snd_info_entry *entry;
373 
374 	entry = snd_info_create_module_entry(THIS_MODULE, "devices", NULL);
375 	if (!entry)
376 		return -ENOMEM;
377 	entry->c.text.read = snd_minor_info_read;
378 	return snd_info_register(entry); /* freed in error path */
379 }
380 #endif /* CONFIG_SND_PROC_FS */
381 
382 /*
383  *  INIT PART
384  */
385 
386 static int __init alsa_sound_init(void)
387 {
388 	snd_major = major;
389 	snd_ecards_limit = cards_limit;
390 	if (register_chrdev(major, "alsa", &snd_fops)) {
391 		pr_err("ALSA core: unable to register native major device number %d\n", major);
392 		return -EIO;
393 	}
394 	if (snd_info_init() < 0) {
395 		unregister_chrdev(major, "alsa");
396 		return -ENOMEM;
397 	}
398 #ifndef MODULE
399 	pr_info("Advanced Linux Sound Architecture Driver Initialized.\n");
400 #endif
401 	return 0;
402 }
403 
404 static void __exit alsa_sound_exit(void)
405 {
406 	snd_info_done();
407 	unregister_chrdev(major, "alsa");
408 }
409 
410 subsys_initcall(alsa_sound_init);
411 module_exit(alsa_sound_exit);
412