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 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(dev: &mreg->card_ptr->card_dev);
112 } else
113 private_data = NULL;
114 mutex_unlock(lock: &sound_mutex);
115 return private_data;
116}
117EXPORT_SYMBOL(snd_lookup_minor_data);
118
119#ifdef CONFIG_MODULES
120static struct snd_minor *autoload_device(unsigned int minor)
121{
122 int dev;
123 mutex_unlock(lock: &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(card: 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
144static 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(lock: &sound_mutex);
159 return -ENODEV;
160 }
161 }
162 new_fops = fops_get(mptr->f_ops);
163 mutex_unlock(lock: &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
173static 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
181static 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
204static 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 */
252int 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(size: 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(dev: device);
282 if (err < 0)
283 goto error;
284
285 snd_minors[minor] = preg;
286 error:
287 mutex_unlock(lock: &sound_mutex);
288 if (err < 0)
289 kfree(objp: preg);
290 return err;
291}
292EXPORT_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 */
303int 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(objp: preg);
315 break;
316 }
317 }
318 mutex_unlock(lock: &sound_mutex);
319 if (minor >= ARRAY_SIZE(snd_minors))
320 return -ENOENT;
321 return 0;
322}
323EXPORT_SYMBOL(snd_unregister_device);
324
325#ifdef CONFIG_SND_PROC_FS
326/*
327 * INFO PART
328 */
329static 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
353static 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(lock: &sound_mutex);
377}
378
379int __init snd_minor_info_init(void)
380{
381 struct snd_info_entry *entry;
382
383 entry = snd_info_create_module_entry(THIS_MODULE, name: "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
395static int __init alsa_sound_init(void)
396{
397 snd_major = major;
398 snd_ecards_limit = cards_limit;
399 if (register_chrdev(major, name: "alsa", fops: &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, name: "alsa");
405 return -ENOMEM;
406 }
407
408#ifdef CONFIG_SND_DEBUG
409 sound_debugfs_root = debugfs_create_dir(name: "sound", NULL);
410#endif
411#ifndef MODULE
412 pr_info("Advanced Linux Sound Architecture Driver Initialized.\n");
413#endif
414 return 0;
415}
416
417static void __exit alsa_sound_exit(void)
418{
419#ifdef CONFIG_SND_DEBUG
420 debugfs_remove(dentry: sound_debugfs_root);
421#endif
422 snd_info_done();
423 unregister_chrdev(major, name: "alsa");
424}
425
426subsys_initcall(alsa_sound_init);
427module_exit(alsa_sound_exit);
428

source code of linux/sound/core/sound.c