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)(T: &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 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(lock: &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(card: ref);
132 } else if (dev == SNDRV_MINOR_GLOBAL) {
133 /* /dev/aloadSEQ */
134 snd_request_other(minor);
135 }
136 mutex_lock(lock: &sound_mutex); /* reacquire 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)(T: &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(dev: device);
279 if (err < 0)
280 goto error;
281
282 snd_minors[minor] = preg;
283 error:
284 if (err < 0)
285 kfree(objp: 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)(T: &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(objp: 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)(T: &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, name: "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, name: "alsa", fops: &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, name: "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, name: "alsa");
418}
419
420subsys_initcall(alsa_sound_init);
421module_exit(alsa_sound_exit);
422