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