1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Sound core. This file is composed of two parts. sound_class
4 * which is common to both OSS and ALSA and OSS sound core which
5 * is used OSS or emulation of it.
6 */
7
8 /*
9 * First, the common part.
10 */
11 #include <linux/module.h>
12 #include <linux/device.h>
13 #include <linux/err.h>
14 #include <linux/kdev_t.h>
15 #include <linux/major.h>
16 #include <sound/core.h>
17
18 #ifdef CONFIG_SOUND_OSS_CORE
19 static int __init init_oss_soundcore(void);
20 static void cleanup_oss_soundcore(void);
21 #else
22 static inline int init_oss_soundcore(void) { return 0; }
23 static inline void cleanup_oss_soundcore(void) { }
24 #endif
25
26 struct class *sound_class;
27 EXPORT_SYMBOL(sound_class);
28
29 MODULE_DESCRIPTION("Core sound module");
30 MODULE_AUTHOR("Alan Cox");
31 MODULE_LICENSE("GPL");
32
33 static char *sound_devnode(struct device *dev, umode_t *mode)
34 {
35 if (MAJOR(dev->devt) == SOUND_MAJOR)
36 return NULL;
37 return kasprintf(GFP_KERNEL, "snd/%s", dev_name(dev));
38 }
39
40 static int __init init_soundcore(void)
41 {
42 int rc;
43
44 rc = init_oss_soundcore();
45 if (rc)
46 return rc;
47
48 sound_class = class_create(THIS_MODULE, "sound");
49 if (IS_ERR(sound_class)) {
50 cleanup_oss_soundcore();
51 return PTR_ERR(sound_class);
52 }
53
54 sound_class->devnode = sound_devnode;
55
56 return 0;
57 }
58
59 static void __exit cleanup_soundcore(void)
60 {
61 cleanup_oss_soundcore();
62 class_destroy(sound_class);
63 }
64
65 subsys_initcall(init_soundcore);
66 module_exit(cleanup_soundcore);
67
68
69 #ifdef CONFIG_SOUND_OSS_CORE
70 /*
71 * OSS sound core handling. Breaks out sound functions to submodules
72 *
73 * Author: Alan Cox <alan@lxorguk.ukuu.org.uk>
74 *
75 * Fixes:
76 *
77 * --------------------
78 *
79 * Top level handler for the sound subsystem. Various devices can
80 * plug into this. The fact they don't all go via OSS doesn't mean
81 * they don't have to implement the OSS API. There is a lot of logic
82 * to keeping much of the OSS weight out of the code in a compatibility
83 * module, but it's up to the driver to rember to load it...
84 *
85 * The code provides a set of functions for registration of devices
86 * by type. This is done rather than providing a single call so that
87 * we can hide any future changes in the internals (eg when we go to
88 * 32bit dev_t) from the modules and their interface.
89 *
90 * Secondly we need to allocate the dsp, dsp16 and audio devices as
91 * one. Thus we misuse the chains a bit to simplify this.
92 *
93 * Thirdly to make it more fun and for 2.3.x and above we do all
94 * of this using fine grained locking.
95 *
96 * FIXME: we have to resolve modules and fine grained load/unload
97 * locking at some point in 2.3.x.
98 */
99
100 #include <linux/init.h>
101 #include <linux/slab.h>
102 #include <linux/types.h>
103 #include <linux/kernel.h>
104 #include <linux/sound.h>
105 #include <linux/kmod.h>
106
107 #define SOUND_STEP 16
108
109 struct sound_unit
110 {
111 int unit_minor;
112 const struct file_operations *unit_fops;
113 struct sound_unit *next;
114 char name[32];
115 };
116
117 /*
118 * By default, OSS sound_core claims full legacy minor range (0-255)
119 * of SOUND_MAJOR to trap open attempts to any sound minor and
120 * requests modules using custom sound-slot/service-* module aliases.
121 * The only benefit of doing this is allowing use of custom module
122 * aliases instead of the standard char-major-* ones. This behavior
123 * prevents alternative OSS implementation and is scheduled to be
124 * removed.
125 *
126 * CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss kernel
127 * parameter are added to allow distros and developers to try and
128 * switch to alternative implementations without needing to rebuild
129 * the kernel in the meantime. If preclaim_oss is non-zero, the
130 * kernel will behave the same as before. All SOUND_MAJOR minors are
131 * preclaimed and the custom module aliases along with standard chrdev
132 * ones are emitted if a missing device is opened. If preclaim_oss is
133 * zero, sound_core only grabs what's actually in use and for missing
134 * devices only the standard chrdev aliases are requested.
135 *
136 * All these clutters are scheduled to be removed along with
137 * sound-slot/service-* module aliases.
138 */
139 #ifdef CONFIG_SOUND_OSS_CORE_PRECLAIM
140 static int preclaim_oss = 1;
141 #else
142 static int preclaim_oss = 0;
143 #endif
144
145 module_param(preclaim_oss, int, 0444);
146
147 static int soundcore_open(struct inode *, struct file *);
148
149 static const struct file_operations soundcore_fops =
150 {
151 /* We must have an owner or the module locking fails */
152 .owner = THIS_MODULE,
153 .open = soundcore_open,
154 .llseek = noop_llseek,
155 };
156
157 /*
158 * Low level list operator. Scan the ordered list, find a hole and
159 * join into it. Called with the lock asserted
160 */
161
162 static int __sound_insert_unit(struct sound_unit * s, struct sound_unit **list, const struct file_operations *fops, int index, int low, int top)
163 {
164 int n=low;
165
166 if (index < 0) { /* first free */
167
168 while (*list && (*list)->unit_minor<n)
169 list=&((*list)->next);
170
171 while(n<top)
172 {
173 /* Found a hole ? */
174 if(*list==NULL || (*list)->unit_minor>n)
175 break;
176 list=&((*list)->next);
177 n+=SOUND_STEP;
178 }
179
180 if(n>=top)
181 return -ENOENT;
182 } else {
183 n = low+(index*16);
184 while (*list) {
185 if ((*list)->unit_minor==n)
186 return -EBUSY;
187 if ((*list)->unit_minor>n)
188 break;
189 list=&((*list)->next);
190 }
191 }
192
193 /*
194 * Fill it in
195 */
196
197 s->unit_minor=n;
198 s->unit_fops=fops;
199
200 /*
201 * Link it
202 */
203
204 s->next=*list;
205 *list=s;
206
207
208 return n;
209 }
210
211 /*
212 * Remove a node from the chain. Called with the lock asserted
213 */
214
215 static struct sound_unit *__sound_remove_unit(struct sound_unit **list, int unit)
216 {
217 while(*list)
218 {
219 struct sound_unit *p=*list;
220 if(p->unit_minor==unit)
221 {
222 *list=p->next;
223 return p;
224 }
225 list=&(p->next);
226 }
227 printk(KERN_ERR "Sound device %d went missing!\n", unit);
228 return NULL;
229 }
230
231 /*
232 * This lock guards the sound loader list.
233 */
234
235 static DEFINE_SPINLOCK(sound_loader_lock);
236
237 /*
238 * Allocate the controlling structure and add it to the sound driver
239 * list. Acquires locks as needed
240 */
241
242 static int sound_insert_unit(struct sound_unit **list, const struct file_operations *fops, int index, int low, int top, const char *name, umode_t mode, struct device *dev)
243 {
244 struct sound_unit *s = kmalloc(sizeof(*s), GFP_KERNEL);
245 int r;
246
247 if (!s)
248 return -ENOMEM;
249
250 spin_lock(&sound_loader_lock);
251 retry:
252 r = __sound_insert_unit(s, list, fops, index, low, top);
253 spin_unlock(&sound_loader_lock);
254
255 if (r < 0)
256 goto fail;
257 else if (r < SOUND_STEP)
258 sprintf(s->name, "sound/%s", name);
259 else
260 sprintf(s->name, "sound/%s%d", name, r / SOUND_STEP);
261
262 if (!preclaim_oss) {
263 /*
264 * Something else might have grabbed the minor. If
265 * first free slot is requested, rescan with @low set
266 * to the next unit; otherwise, -EBUSY.
267 */
268 r = __register_chrdev(SOUND_MAJOR, s->unit_minor, 1, s->name,
269 &soundcore_fops);
270 if (r < 0) {
271 spin_lock(&sound_loader_lock);
272 __sound_remove_unit(list, s->unit_minor);
273 if (index < 0) {
274 low = s->unit_minor + SOUND_STEP;
275 goto retry;
276 }
277 spin_unlock(&sound_loader_lock);
278 r = -EBUSY;
279 goto fail;
280 }
281 }
282
283 device_create(sound_class, dev, MKDEV(SOUND_MAJOR, s->unit_minor),
284 NULL, "%s", s->name+6);
285 return s->unit_minor;
286
287 fail:
288 kfree(s);
289 return r;
290 }
291
292 /*
293 * Remove a unit. Acquires locks as needed. The drivers MUST have
294 * completed the removal before their file operations become
295 * invalid.
296 */
297
298 static void sound_remove_unit(struct sound_unit **list, int unit)
299 {
300 struct sound_unit *p;
301
302 spin_lock(&sound_loader_lock);
303 p = __sound_remove_unit(list, unit);
304 spin_unlock(&sound_loader_lock);
305 if (p) {
306 if (!preclaim_oss)
307 __unregister_chrdev(SOUND_MAJOR, p->unit_minor, 1,
308 p->name);
309 device_destroy(sound_class, MKDEV(SOUND_MAJOR, p->unit_minor));
310 kfree(p);
311 }
312 }
313
314 /*
315 * Allocations
316 *
317 * 0 *16 Mixers
318 * 1 *8 Sequencers
319 * 2 *16 Midi
320 * 3 *16 DSP
321 * 4 *16 SunDSP
322 * 5 *16 DSP16
323 * 6 -- sndstat (obsolete)
324 * 7 *16 unused
325 * 8 -- alternate sequencer (see above)
326 * 9 *16 raw synthesizer access
327 * 10 *16 unused
328 * 11 *16 unused
329 * 12 *16 unused
330 * 13 *16 unused
331 * 14 *16 unused
332 * 15 *16 unused
333 */
334
335 static struct sound_unit *chains[SOUND_STEP];
336
337 /**
338 * register_sound_special_device - register a special sound node
339 * @fops: File operations for the driver
340 * @unit: Unit number to allocate
341 * @dev: device pointer
342 *
343 * Allocate a special sound device by minor number from the sound
344 * subsystem.
345 *
346 * Return: The allocated number is returned on success. On failure,
347 * a negative error code is returned.
348 */
349
350 int register_sound_special_device(const struct file_operations *fops, int unit,
351 struct device *dev)
352 {
353 const int chain = unit % SOUND_STEP;
354 int max_unit = 256;
355 const char *name;
356 char _name[16];
357
358 switch (chain) {
359 case 0:
360 name = "mixer";
361 break;
362 case 1:
363 name = "sequencer";
364 if (unit >= SOUND_STEP)
365 goto __unknown;
366 max_unit = unit + 1;
367 break;
368 case 2:
369 name = "midi";
370 break;
371 case 3:
372 name = "dsp";
373 break;
374 case 4:
375 name = "audio";
376 break;
377 case 5:
378 name = "dspW";
379 break;
380 case 8:
381 name = "sequencer2";
382 if (unit >= SOUND_STEP)
383 goto __unknown;
384 max_unit = unit + 1;
385 break;
386 case 9:
387 name = "dmmidi";
388 break;
389 case 10:
390 name = "dmfm";
391 break;
392 case 12:
393 name = "adsp";
394 break;
395 case 13:
396 name = "amidi";
397 break;
398 case 14:
399 name = "admmidi";
400 break;
401 default:
402 {
403 __unknown:
404 sprintf(_name, "unknown%d", chain);
405 if (unit >= SOUND_STEP)
406 strcat(_name, "-");
407 name = _name;
408 }
409 break;
410 }
411 return sound_insert_unit(&chains[chain], fops, -1, unit, max_unit,
412 name, 0600, dev);
413 }
414
415 EXPORT_SYMBOL(register_sound_special_device);
416
417 int register_sound_special(const struct file_operations *fops, int unit)
418 {
419 return register_sound_special_device(fops, unit, NULL);
420 }
421
422 EXPORT_SYMBOL(register_sound_special);
423
424 /**
425 * register_sound_mixer - register a mixer device
426 * @fops: File operations for the driver
427 * @dev: Unit number to allocate
428 *
429 * Allocate a mixer device. Unit is the number of the mixer requested.
430 * Pass -1 to request the next free mixer unit.
431 *
432 * Return: On success, the allocated number is returned. On failure,
433 * a negative error code is returned.
434 */
435
436 int register_sound_mixer(const struct file_operations *fops, int dev)
437 {
438 return sound_insert_unit(&chains[0], fops, dev, 0, 128,
439 "mixer", 0600, NULL);
440 }
441
442 EXPORT_SYMBOL(register_sound_mixer);
443
444 /*
445 * DSP's are registered as a triple. Register only one and cheat
446 * in open - see below.
447 */
448
449 /**
450 * register_sound_dsp - register a DSP device
451 * @fops: File operations for the driver
452 * @dev: Unit number to allocate
453 *
454 * Allocate a DSP device. Unit is the number of the DSP requested.
455 * Pass -1 to request the next free DSP unit.
456 *
457 * This function allocates both the audio and dsp device entries together
458 * and will always allocate them as a matching pair - eg dsp3/audio3
459 *
460 * Return: On success, the allocated number is returned. On failure,
461 * a negative error code is returned.
462 */
463
464 int register_sound_dsp(const struct file_operations *fops, int dev)
465 {
466 return sound_insert_unit(&chains[3], fops, dev, 3, 131,
467 "dsp", 0600, NULL);
468 }
469
470 EXPORT_SYMBOL(register_sound_dsp);
471
472 /**
473 * unregister_sound_special - unregister a special sound device
474 * @unit: unit number to allocate
475 *
476 * Release a sound device that was allocated with
477 * register_sound_special(). The unit passed is the return value from
478 * the register function.
479 */
480
481
482 void unregister_sound_special(int unit)
483 {
484 sound_remove_unit(&chains[unit % SOUND_STEP], unit);
485 }
486
487 EXPORT_SYMBOL(unregister_sound_special);
488
489 /**
490 * unregister_sound_mixer - unregister a mixer
491 * @unit: unit number to allocate
492 *
493 * Release a sound device that was allocated with register_sound_mixer().
494 * The unit passed is the return value from the register function.
495 */
496
497 void unregister_sound_mixer(int unit)
498 {
499 sound_remove_unit(&chains[0], unit);
500 }
501
502 EXPORT_SYMBOL(unregister_sound_mixer);
503
504 /**
505 * unregister_sound_dsp - unregister a DSP device
506 * @unit: unit number to allocate
507 *
508 * Release a sound device that was allocated with register_sound_dsp().
509 * The unit passed is the return value from the register function.
510 *
511 * Both of the allocated units are released together automatically.
512 */
513
514 void unregister_sound_dsp(int unit)
515 {
516 sound_remove_unit(&chains[3], unit);
517 }
518
519
520 EXPORT_SYMBOL(unregister_sound_dsp);
521
522 static struct sound_unit *__look_for_unit(int chain, int unit)
523 {
524 struct sound_unit *s;
525
526 s=chains[chain];
527 while(s && s->unit_minor <= unit)
528 {
529 if(s->unit_minor==unit)
530 return s;
531 s=s->next;
532 }
533 return NULL;
534 }
535
536 static int soundcore_open(struct inode *inode, struct file *file)
537 {
538 int chain;
539 int unit = iminor(inode);
540 struct sound_unit *s;
541 const struct file_operations *new_fops = NULL;
542
543 chain=unit&0x0F;
544 if(chain==4 || chain==5) /* dsp/audio/dsp16 */
545 {
546 unit&=0xF0;
547 unit|=3;
548 chain=3;
549 }
550
551 spin_lock(&sound_loader_lock);
552 s = __look_for_unit(chain, unit);
553 if (s)
554 new_fops = fops_get(s->unit_fops);
555 if (preclaim_oss && !new_fops) {
556 spin_unlock(&sound_loader_lock);
557
558 /*
559 * Please, don't change this order or code.
560 * For ALSA slot means soundcard and OSS emulation code
561 * comes as add-on modules which aren't depend on
562 * ALSA toplevel modules for soundcards, thus we need
563 * load them at first. [Jaroslav Kysela <perex@jcu.cz>]
564 */
565 request_module("sound-slot-%i", unit>>4);
566 request_module("sound-service-%i-%i", unit>>4, chain);
567
568 /*
569 * sound-slot/service-* module aliases are scheduled
570 * for removal in favor of the standard char-major-*
571 * module aliases. For the time being, generate both
572 * the legacy and standard module aliases to ease
573 * transition.
574 */
575 if (request_module("char-major-%d-%d", SOUND_MAJOR, unit) > 0)
576 request_module("char-major-%d", SOUND_MAJOR);
577
578 spin_lock(&sound_loader_lock);
579 s = __look_for_unit(chain, unit);
580 if (s)
581 new_fops = fops_get(s->unit_fops);
582 }
583 spin_unlock(&sound_loader_lock);
584 if (new_fops) {
585 /*
586 * We rely upon the fact that we can't be unloaded while the
587 * subdriver is there.
588 */
589 int err = 0;
590 replace_fops(file, new_fops);
591
592 if (file->f_op->open)
593 err = file->f_op->open(inode,file);
594
595 return err;
596 }
597 return -ENODEV;
598 }
599
600 MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);
601
602 static void cleanup_oss_soundcore(void)
603 {
604 /* We have nothing to really do here - we know the lists must be
605 empty */
606 unregister_chrdev(SOUND_MAJOR, "sound");
607 }
608
609 static int __init init_oss_soundcore(void)
610 {
611 if (preclaim_oss &&
612 register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) < 0) {
613 printk(KERN_ERR "soundcore: sound device already in use.\n");
614 return -EBUSY;
615 }
616
617 return 0;
618 }
619
620 #endif /* CONFIG_SOUND_OSS_CORE */