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 <linux/debugfs.h>
13 #include <sound/core.h>
14 #include <sound/minors.h>
15 #include <sound/info.h>
16 #include <sound/control.h>
17 #include <sound/initval.h>
18 #include <linux/kmod.h>
19 #include <linux/mutex.h>
20 
21 static int major = CONFIG_SND_MAJOR;
22 int snd_major;
23 EXPORT_SYMBOL(snd_major);
24 
25 static int cards_limit = 1;
26 
27 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
28 MODULE_DESCRIPTION("Advanced Linux Sound Architecture driver for soundcards.");
29 MODULE_LICENSE("GPL");
30 module_param(major, int, 0444);
31 MODULE_PARM_DESC(major, "Major # for sound driver.");
32 module_param(cards_limit, int, 0444);
33 MODULE_PARM_DESC(cards_limit, "Count of auto-loadable soundcards.");
34 MODULE_ALIAS_CHARDEV_MAJOR(CONFIG_SND_MAJOR);
35 
36 /* this one holds the actual max. card number currently available.
37  * as default, it's identical with cards_limit option.  when more
38  * modules are loaded manually, this limit number increases, too.
39  */
40 int snd_ecards_limit;
41 EXPORT_SYMBOL(snd_ecards_limit);
42 
43 #ifdef CONFIG_SND_DEBUG
44 struct dentry *sound_debugfs_root;
45 EXPORT_SYMBOL_GPL(sound_debugfs_root);
46 #endif
47 
48 static struct snd_minor *snd_minors[SNDRV_OS_MINORS];
49 static DEFINE_MUTEX(sound_mutex);
50 
51 #ifdef CONFIG_MODULES
52 
53 /**
54  * snd_request_card - try to load the card module
55  * @card: the card number
56  *
57  * Tries to load the module "snd-card-X" for the given card number
58  * via request_module.  Returns immediately if already loaded.
59  */
snd_request_card(int card)60 void snd_request_card(int card)
61 {
62 	if (snd_card_locked(card))
63 		return;
64 	if (card < 0 || card >= cards_limit)
65 		return;
66 	request_module("snd-card-%i", card);
67 }
68 EXPORT_SYMBOL(snd_request_card);
69 
snd_request_other(int minor)70 static void snd_request_other(int minor)
71 {
72 	char *str;
73 
74 	switch (minor) {
75 	case SNDRV_MINOR_SEQUENCER:	str = "snd-seq";	break;
76 	case SNDRV_MINOR_TIMER:		str = "snd-timer";	break;
77 	default:			return;
78 	}
79 	request_module(str);
80 }
81 
82 #endif	/* modular kernel */
83 
84 /**
85  * snd_lookup_minor_data - get user data of a registered device
86  * @minor: the minor number
87  * @type: device type (SNDRV_DEVICE_TYPE_XXX)
88  *
89  * Checks that a minor device with the specified type is registered, and returns
90  * its user data pointer.
91  *
92  * This function increments the reference counter of the card instance
93  * if an associated instance with the given minor number and type is found.
94  * The caller must call snd_card_unref() appropriately later.
95  *
96  * Return: The user data pointer if the specified device is found. %NULL
97  * otherwise.
98  */
snd_lookup_minor_data(unsigned int minor,int type)99 void *snd_lookup_minor_data(unsigned int minor, int type)
100 {
101 	struct snd_minor *mreg;
102 	void *private_data;
103 
104 	if (minor >= ARRAY_SIZE(snd_minors))
105 		return NULL;
106 	mutex_lock(&sound_mutex);
107 	mreg = snd_minors[minor];
108 	if (mreg && mreg->type == type) {
109 		private_data = mreg->private_data;
110 		if (private_data && mreg->card_ptr)
111 			get_device(&mreg->card_ptr->card_dev);
112 	} else
113 		private_data = NULL;
114 	mutex_unlock(&sound_mutex);
115 	return private_data;
116 }
117 EXPORT_SYMBOL(snd_lookup_minor_data);
118 
119 #ifdef CONFIG_MODULES
autoload_device(unsigned int minor)120 static struct snd_minor *autoload_device(unsigned int minor)
121 {
122 	int dev;
123 	mutex_unlock(&sound_mutex); /* release lock temporarily */
124 	dev = SNDRV_MINOR_DEVICE(minor);
125 	if (dev == SNDRV_MINOR_CONTROL) {
126 		/* /dev/aloadC? */
127 		int card = SNDRV_MINOR_CARD(minor);
128 		struct snd_card *ref = snd_card_ref(card);
129 		if (!ref)
130 			snd_request_card(card);
131 		else
132 			snd_card_unref(ref);
133 	} else if (dev == SNDRV_MINOR_GLOBAL) {
134 		/* /dev/aloadSEQ */
135 		snd_request_other(minor);
136 	}
137 	mutex_lock(&sound_mutex); /* reacuire lock */
138 	return snd_minors[minor];
139 }
140 #else /* !CONFIG_MODULES */
141 #define autoload_device(minor)	NULL
142 #endif /* CONFIG_MODULES */
143 
snd_open(struct inode * inode,struct file * file)144 static int snd_open(struct inode *inode, struct file *file)
145 {
146 	unsigned int minor = iminor(inode);
147 	struct snd_minor *mptr = NULL;
148 	const struct file_operations *new_fops;
149 	int err = 0;
150 
151 	if (minor >= ARRAY_SIZE(snd_minors))
152 		return -ENODEV;
153 	mutex_lock(&sound_mutex);
154 	mptr = snd_minors[minor];
155 	if (mptr == NULL) {
156 		mptr = autoload_device(minor);
157 		if (!mptr) {
158 			mutex_unlock(&sound_mutex);
159 			return -ENODEV;
160 		}
161 	}
162 	new_fops = fops_get(mptr->f_ops);
163 	mutex_unlock(&sound_mutex);
164 	if (!new_fops)
165 		return -ENODEV;
166 	replace_fops(file, new_fops);
167 
168 	if (file->f_op->open)
169 		err = file->f_op->open(inode, file);
170 	return err;
171 }
172 
173 static const struct file_operations snd_fops =
174 {
175 	.owner =	THIS_MODULE,
176 	.open =		snd_open,
177 	.llseek =	noop_llseek,
178 };
179 
180 #ifdef CONFIG_SND_DYNAMIC_MINORS
snd_find_free_minor(int type,struct snd_card * card,int dev)181 static int snd_find_free_minor(int type, struct snd_card *card, int dev)
182 {
183 	int minor;
184 
185 	/* static minors for module auto loading */
186 	if (type == SNDRV_DEVICE_TYPE_SEQUENCER)
187 		return SNDRV_MINOR_SEQUENCER;
188 	if (type == SNDRV_DEVICE_TYPE_TIMER)
189 		return SNDRV_MINOR_TIMER;
190 
191 	for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor) {
192 		/* skip static minors still used for module auto loading */
193 		if (SNDRV_MINOR_DEVICE(minor) == SNDRV_MINOR_CONTROL)
194 			continue;
195 		if (minor == SNDRV_MINOR_SEQUENCER ||
196 		    minor == SNDRV_MINOR_TIMER)
197 			continue;
198 		if (!snd_minors[minor])
199 			return minor;
200 	}
201 	return -EBUSY;
202 }
203 #else
snd_find_free_minor(int type,struct snd_card * card,int dev)204 static int snd_find_free_minor(int type, struct snd_card *card, int dev)
205 {
206 	int minor;
207 
208 	switch (type) {
209 	case SNDRV_DEVICE_TYPE_SEQUENCER:
210 	case SNDRV_DEVICE_TYPE_TIMER:
211 		minor = type;
212 		break;
213 	case SNDRV_DEVICE_TYPE_CONTROL:
214 		if (snd_BUG_ON(!card))
215 			return -EINVAL;
216 		minor = SNDRV_MINOR(card->number, type);
217 		break;
218 	case SNDRV_DEVICE_TYPE_HWDEP:
219 	case SNDRV_DEVICE_TYPE_RAWMIDI:
220 	case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
221 	case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
222 	case SNDRV_DEVICE_TYPE_COMPRESS:
223 		if (snd_BUG_ON(!card))
224 			return -EINVAL;
225 		minor = SNDRV_MINOR(card->number, type + dev);
226 		break;
227 	default:
228 		return -EINVAL;
229 	}
230 	if (snd_BUG_ON(minor < 0 || minor >= SNDRV_OS_MINORS))
231 		return -EINVAL;
232 	if (snd_minors[minor])
233 		return -EBUSY;
234 	return minor;
235 }
236 #endif
237 
238 /**
239  * snd_register_device - Register the ALSA device file for the card
240  * @type: the device type, SNDRV_DEVICE_TYPE_XXX
241  * @card: the card instance
242  * @dev: the device index
243  * @f_ops: the file operations
244  * @private_data: user pointer for f_ops->open()
245  * @device: the device to register
246  *
247  * Registers an ALSA device file for the given card.
248  * The operators have to be set in reg parameter.
249  *
250  * Return: Zero if successful, or a negative error code on failure.
251  */
snd_register_device(int type,struct snd_card * card,int dev,const struct file_operations * f_ops,void * private_data,struct device * device)252 int snd_register_device(int type, struct snd_card *card, int dev,
253 			const struct file_operations *f_ops,
254 			void *private_data, struct device *device)
255 {
256 	int minor;
257 	int err = 0;
258 	struct snd_minor *preg;
259 
260 	if (snd_BUG_ON(!device))
261 		return -EINVAL;
262 
263 	preg = kmalloc(sizeof *preg, GFP_KERNEL);
264 	if (preg == NULL)
265 		return -ENOMEM;
266 	preg->type = type;
267 	preg->card = card ? card->number : -1;
268 	preg->device = dev;
269 	preg->f_ops = f_ops;
270 	preg->private_data = private_data;
271 	preg->card_ptr = card;
272 	mutex_lock(&sound_mutex);
273 	minor = snd_find_free_minor(type, card, dev);
274 	if (minor < 0) {
275 		err = minor;
276 		goto error;
277 	}
278 
279 	preg->dev = device;
280 	device->devt = MKDEV(major, minor);
281 	err = device_add(device);
282 	if (err < 0)
283 		goto error;
284 
285 	snd_minors[minor] = preg;
286  error:
287 	mutex_unlock(&sound_mutex);
288 	if (err < 0)
289 		kfree(preg);
290 	return err;
291 }
292 EXPORT_SYMBOL(snd_register_device);
293 
294 /**
295  * snd_unregister_device - unregister the device on the given card
296  * @dev: the device instance
297  *
298  * Unregisters the device file already registered via
299  * snd_register_device().
300  *
301  * Return: Zero if successful, or a negative error code on failure.
302  */
snd_unregister_device(struct device * dev)303 int snd_unregister_device(struct device *dev)
304 {
305 	int minor;
306 	struct snd_minor *preg;
307 
308 	mutex_lock(&sound_mutex);
309 	for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor) {
310 		preg = snd_minors[minor];
311 		if (preg && preg->dev == dev) {
312 			snd_minors[minor] = NULL;
313 			device_del(dev);
314 			kfree(preg);
315 			break;
316 		}
317 	}
318 	mutex_unlock(&sound_mutex);
319 	if (minor >= ARRAY_SIZE(snd_minors))
320 		return -ENOENT;
321 	return 0;
322 }
323 EXPORT_SYMBOL(snd_unregister_device);
324 
325 #ifdef CONFIG_SND_PROC_FS
326 /*
327  *  INFO PART
328  */
snd_device_type_name(int type)329 static const char *snd_device_type_name(int type)
330 {
331 	switch (type) {
332 	case SNDRV_DEVICE_TYPE_CONTROL:
333 		return "control";
334 	case SNDRV_DEVICE_TYPE_HWDEP:
335 		return "hardware dependent";
336 	case SNDRV_DEVICE_TYPE_RAWMIDI:
337 		return "raw midi";
338 	case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
339 		return "digital audio playback";
340 	case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
341 		return "digital audio capture";
342 	case SNDRV_DEVICE_TYPE_SEQUENCER:
343 		return "sequencer";
344 	case SNDRV_DEVICE_TYPE_TIMER:
345 		return "timer";
346 	case SNDRV_DEVICE_TYPE_COMPRESS:
347 		return "compress";
348 	default:
349 		return "?";
350 	}
351 }
352 
snd_minor_info_read(struct snd_info_entry * entry,struct snd_info_buffer * buffer)353 static void snd_minor_info_read(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
354 {
355 	int minor;
356 	struct snd_minor *mptr;
357 
358 	mutex_lock(&sound_mutex);
359 	for (minor = 0; minor < SNDRV_OS_MINORS; ++minor) {
360 		mptr = snd_minors[minor];
361 		if (!mptr)
362 			continue;
363 		if (mptr->card >= 0) {
364 			if (mptr->device >= 0)
365 				snd_iprintf(buffer, "%3i: [%2i-%2i]: %s\n",
366 					    minor, mptr->card, mptr->device,
367 					    snd_device_type_name(mptr->type));
368 			else
369 				snd_iprintf(buffer, "%3i: [%2i]   : %s\n",
370 					    minor, mptr->card,
371 					    snd_device_type_name(mptr->type));
372 		} else
373 			snd_iprintf(buffer, "%3i:        : %s\n", minor,
374 				    snd_device_type_name(mptr->type));
375 	}
376 	mutex_unlock(&sound_mutex);
377 }
378 
snd_minor_info_init(void)379 int __init snd_minor_info_init(void)
380 {
381 	struct snd_info_entry *entry;
382 
383 	entry = snd_info_create_module_entry(THIS_MODULE, "devices", NULL);
384 	if (!entry)
385 		return -ENOMEM;
386 	entry->c.text.read = snd_minor_info_read;
387 	return snd_info_register(entry); /* freed in error path */
388 }
389 #endif /* CONFIG_SND_PROC_FS */
390 
391 /*
392  *  INIT PART
393  */
394 
alsa_sound_init(void)395 static int __init alsa_sound_init(void)
396 {
397 	snd_major = major;
398 	snd_ecards_limit = cards_limit;
399 	if (register_chrdev(major, "alsa", &snd_fops)) {
400 		pr_err("ALSA core: unable to register native major device number %d\n", major);
401 		return -EIO;
402 	}
403 	if (snd_info_init() < 0) {
404 		unregister_chrdev(major, "alsa");
405 		return -ENOMEM;
406 	}
407 
408 #ifdef CONFIG_SND_DEBUG
409 	sound_debugfs_root = debugfs_create_dir("sound", NULL);
410 #endif
411 #ifndef MODULE
412 	pr_info("Advanced Linux Sound Architecture Driver Initialized.\n");
413 #endif
414 	return 0;
415 }
416 
alsa_sound_exit(void)417 static void __exit alsa_sound_exit(void)
418 {
419 #ifdef CONFIG_SND_DEBUG
420 	debugfs_remove(sound_debugfs_root);
421 #endif
422 	snd_info_done();
423 	unregister_chrdev(major, "alsa");
424 }
425 
426 subsys_initcall(alsa_sound_init);
427 module_exit(alsa_sound_exit);
428