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
init_oss_soundcore(void)22 static inline int init_oss_soundcore(void) { return 0; }
cleanup_oss_soundcore(void)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
sound_devnode(struct device * dev,umode_t * mode)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
init_soundcore(void)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
cleanup_soundcore(void)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 static int preclaim_oss = IS_ENABLED(CONFIG_SOUND_OSS_CORE_PRECLAIM);
140
141 module_param(preclaim_oss, int, 0444);
142
143 static int soundcore_open(struct inode *, struct file *);
144
145 static const struct file_operations soundcore_fops =
146 {
147 /* We must have an owner or the module locking fails */
148 .owner = THIS_MODULE,
149 .open = soundcore_open,
150 .llseek = noop_llseek,
151 };
152
153 /*
154 * Low level list operator. Scan the ordered list, find a hole and
155 * join into it. Called with the lock asserted
156 */
157
__sound_insert_unit(struct sound_unit * s,struct sound_unit ** list,const struct file_operations * fops,int index,int low,int top)158 static int __sound_insert_unit(struct sound_unit * s, struct sound_unit **list, const struct file_operations *fops, int index, int low, int top)
159 {
160 int n=low;
161
162 if (index < 0) { /* first free */
163
164 while (*list && (*list)->unit_minor<n)
165 list=&((*list)->next);
166
167 while(n<top)
168 {
169 /* Found a hole ? */
170 if(*list==NULL || (*list)->unit_minor>n)
171 break;
172 list=&((*list)->next);
173 n+=SOUND_STEP;
174 }
175
176 if(n>=top)
177 return -ENOENT;
178 } else {
179 n = low+(index*16);
180 while (*list) {
181 if ((*list)->unit_minor==n)
182 return -EBUSY;
183 if ((*list)->unit_minor>n)
184 break;
185 list=&((*list)->next);
186 }
187 }
188
189 /*
190 * Fill it in
191 */
192
193 s->unit_minor=n;
194 s->unit_fops=fops;
195
196 /*
197 * Link it
198 */
199
200 s->next=*list;
201 *list=s;
202
203
204 return n;
205 }
206
207 /*
208 * Remove a node from the chain. Called with the lock asserted
209 */
210
__sound_remove_unit(struct sound_unit ** list,int unit)211 static struct sound_unit *__sound_remove_unit(struct sound_unit **list, int unit)
212 {
213 while(*list)
214 {
215 struct sound_unit *p=*list;
216 if(p->unit_minor==unit)
217 {
218 *list=p->next;
219 return p;
220 }
221 list=&(p->next);
222 }
223 printk(KERN_ERR "Sound device %d went missing!\n", unit);
224 return NULL;
225 }
226
227 /*
228 * This lock guards the sound loader list.
229 */
230
231 static DEFINE_SPINLOCK(sound_loader_lock);
232
233 /*
234 * Allocate the controlling structure and add it to the sound driver
235 * list. Acquires locks as needed
236 */
237
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)238 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)
239 {
240 struct sound_unit *s = kmalloc(sizeof(*s), GFP_KERNEL);
241 int r;
242
243 if (!s)
244 return -ENOMEM;
245
246 spin_lock(&sound_loader_lock);
247 retry:
248 r = __sound_insert_unit(s, list, fops, index, low, top);
249 spin_unlock(&sound_loader_lock);
250
251 if (r < 0)
252 goto fail;
253 else if (r < SOUND_STEP)
254 sprintf(s->name, "sound/%s", name);
255 else
256 sprintf(s->name, "sound/%s%d", name, r / SOUND_STEP);
257
258 if (!preclaim_oss) {
259 /*
260 * Something else might have grabbed the minor. If
261 * first free slot is requested, rescan with @low set
262 * to the next unit; otherwise, -EBUSY.
263 */
264 r = __register_chrdev(SOUND_MAJOR, s->unit_minor, 1, s->name,
265 &soundcore_fops);
266 if (r < 0) {
267 spin_lock(&sound_loader_lock);
268 __sound_remove_unit(list, s->unit_minor);
269 if (index < 0) {
270 low = s->unit_minor + SOUND_STEP;
271 goto retry;
272 }
273 spin_unlock(&sound_loader_lock);
274 r = -EBUSY;
275 goto fail;
276 }
277 }
278
279 device_create(sound_class, dev, MKDEV(SOUND_MAJOR, s->unit_minor),
280 NULL, "%s", s->name+6);
281 return s->unit_minor;
282
283 fail:
284 kfree(s);
285 return r;
286 }
287
288 /*
289 * Remove a unit. Acquires locks as needed. The drivers MUST have
290 * completed the removal before their file operations become
291 * invalid.
292 */
293
sound_remove_unit(struct sound_unit ** list,int unit)294 static void sound_remove_unit(struct sound_unit **list, int unit)
295 {
296 struct sound_unit *p;
297
298 spin_lock(&sound_loader_lock);
299 p = __sound_remove_unit(list, unit);
300 spin_unlock(&sound_loader_lock);
301 if (p) {
302 if (!preclaim_oss)
303 __unregister_chrdev(SOUND_MAJOR, p->unit_minor, 1,
304 p->name);
305 device_destroy(sound_class, MKDEV(SOUND_MAJOR, p->unit_minor));
306 kfree(p);
307 }
308 }
309
310 /*
311 * Allocations
312 *
313 * 0 *16 Mixers
314 * 1 *8 Sequencers
315 * 2 *16 Midi
316 * 3 *16 DSP
317 * 4 *16 SunDSP
318 * 5 *16 DSP16
319 * 6 -- sndstat (obsolete)
320 * 7 *16 unused
321 * 8 -- alternate sequencer (see above)
322 * 9 *16 raw synthesizer access
323 * 10 *16 unused
324 * 11 *16 unused
325 * 12 *16 unused
326 * 13 *16 unused
327 * 14 *16 unused
328 * 15 *16 unused
329 */
330
331 static struct sound_unit *chains[SOUND_STEP];
332
333 /**
334 * register_sound_special_device - register a special sound node
335 * @fops: File operations for the driver
336 * @unit: Unit number to allocate
337 * @dev: device pointer
338 *
339 * Allocate a special sound device by minor number from the sound
340 * subsystem.
341 *
342 * Return: The allocated number is returned on success. On failure,
343 * a negative error code is returned.
344 */
345
register_sound_special_device(const struct file_operations * fops,int unit,struct device * dev)346 int register_sound_special_device(const struct file_operations *fops, int unit,
347 struct device *dev)
348 {
349 const int chain = unit % SOUND_STEP;
350 int max_unit = 256;
351 const char *name;
352 char _name[16];
353
354 switch (chain) {
355 case 0:
356 name = "mixer";
357 break;
358 case 1:
359 name = "sequencer";
360 if (unit >= SOUND_STEP)
361 goto __unknown;
362 max_unit = unit + 1;
363 break;
364 case 2:
365 name = "midi";
366 break;
367 case 3:
368 name = "dsp";
369 break;
370 case 4:
371 name = "audio";
372 break;
373 case 5:
374 name = "dspW";
375 break;
376 case 8:
377 name = "sequencer2";
378 if (unit >= SOUND_STEP)
379 goto __unknown;
380 max_unit = unit + 1;
381 break;
382 case 9:
383 name = "dmmidi";
384 break;
385 case 10:
386 name = "dmfm";
387 break;
388 case 12:
389 name = "adsp";
390 break;
391 case 13:
392 name = "amidi";
393 break;
394 case 14:
395 name = "admmidi";
396 break;
397 default:
398 {
399 __unknown:
400 sprintf(_name, "unknown%d", chain);
401 if (unit >= SOUND_STEP)
402 strcat(_name, "-");
403 name = _name;
404 }
405 break;
406 }
407 return sound_insert_unit(&chains[chain], fops, -1, unit, max_unit,
408 name, 0600, dev);
409 }
410
411 EXPORT_SYMBOL(register_sound_special_device);
412
register_sound_special(const struct file_operations * fops,int unit)413 int register_sound_special(const struct file_operations *fops, int unit)
414 {
415 return register_sound_special_device(fops, unit, NULL);
416 }
417
418 EXPORT_SYMBOL(register_sound_special);
419
420 /**
421 * register_sound_mixer - register a mixer device
422 * @fops: File operations for the driver
423 * @dev: Unit number to allocate
424 *
425 * Allocate a mixer device. Unit is the number of the mixer requested.
426 * Pass -1 to request the next free mixer unit.
427 *
428 * Return: On success, the allocated number is returned. On failure,
429 * a negative error code is returned.
430 */
431
register_sound_mixer(const struct file_operations * fops,int dev)432 int register_sound_mixer(const struct file_operations *fops, int dev)
433 {
434 return sound_insert_unit(&chains[0], fops, dev, 0, 128,
435 "mixer", 0600, NULL);
436 }
437
438 EXPORT_SYMBOL(register_sound_mixer);
439
440 /*
441 * DSP's are registered as a triple. Register only one and cheat
442 * in open - see below.
443 */
444
445 /**
446 * register_sound_dsp - register a DSP device
447 * @fops: File operations for the driver
448 * @dev: Unit number to allocate
449 *
450 * Allocate a DSP device. Unit is the number of the DSP requested.
451 * Pass -1 to request the next free DSP unit.
452 *
453 * This function allocates both the audio and dsp device entries together
454 * and will always allocate them as a matching pair - eg dsp3/audio3
455 *
456 * Return: On success, the allocated number is returned. On failure,
457 * a negative error code is returned.
458 */
459
register_sound_dsp(const struct file_operations * fops,int dev)460 int register_sound_dsp(const struct file_operations *fops, int dev)
461 {
462 return sound_insert_unit(&chains[3], fops, dev, 3, 131,
463 "dsp", 0600, NULL);
464 }
465
466 EXPORT_SYMBOL(register_sound_dsp);
467
468 /**
469 * unregister_sound_special - unregister a special sound device
470 * @unit: unit number to allocate
471 *
472 * Release a sound device that was allocated with
473 * register_sound_special(). The unit passed is the return value from
474 * the register function.
475 */
476
477
unregister_sound_special(int unit)478 void unregister_sound_special(int unit)
479 {
480 sound_remove_unit(&chains[unit % SOUND_STEP], unit);
481 }
482
483 EXPORT_SYMBOL(unregister_sound_special);
484
485 /**
486 * unregister_sound_mixer - unregister a mixer
487 * @unit: unit number to allocate
488 *
489 * Release a sound device that was allocated with register_sound_mixer().
490 * The unit passed is the return value from the register function.
491 */
492
unregister_sound_mixer(int unit)493 void unregister_sound_mixer(int unit)
494 {
495 sound_remove_unit(&chains[0], unit);
496 }
497
498 EXPORT_SYMBOL(unregister_sound_mixer);
499
500 /**
501 * unregister_sound_dsp - unregister a DSP device
502 * @unit: unit number to allocate
503 *
504 * Release a sound device that was allocated with register_sound_dsp().
505 * The unit passed is the return value from the register function.
506 *
507 * Both of the allocated units are released together automatically.
508 */
509
unregister_sound_dsp(int unit)510 void unregister_sound_dsp(int unit)
511 {
512 sound_remove_unit(&chains[3], unit);
513 }
514
515
516 EXPORT_SYMBOL(unregister_sound_dsp);
517
__look_for_unit(int chain,int unit)518 static struct sound_unit *__look_for_unit(int chain, int unit)
519 {
520 struct sound_unit *s;
521
522 s=chains[chain];
523 while(s && s->unit_minor <= unit)
524 {
525 if(s->unit_minor==unit)
526 return s;
527 s=s->next;
528 }
529 return NULL;
530 }
531
soundcore_open(struct inode * inode,struct file * file)532 static int soundcore_open(struct inode *inode, struct file *file)
533 {
534 int chain;
535 int unit = iminor(inode);
536 struct sound_unit *s;
537 const struct file_operations *new_fops = NULL;
538
539 chain=unit&0x0F;
540 if(chain==4 || chain==5) /* dsp/audio/dsp16 */
541 {
542 unit&=0xF0;
543 unit|=3;
544 chain=3;
545 }
546
547 spin_lock(&sound_loader_lock);
548 s = __look_for_unit(chain, unit);
549 if (s)
550 new_fops = fops_get(s->unit_fops);
551 if (preclaim_oss && !new_fops) {
552 spin_unlock(&sound_loader_lock);
553
554 /*
555 * Please, don't change this order or code.
556 * For ALSA slot means soundcard and OSS emulation code
557 * comes as add-on modules which aren't depend on
558 * ALSA toplevel modules for soundcards, thus we need
559 * load them at first. [Jaroslav Kysela <perex@jcu.cz>]
560 */
561 request_module("sound-slot-%i", unit>>4);
562 request_module("sound-service-%i-%i", unit>>4, chain);
563
564 /*
565 * sound-slot/service-* module aliases are scheduled
566 * for removal in favor of the standard char-major-*
567 * module aliases. For the time being, generate both
568 * the legacy and standard module aliases to ease
569 * transition.
570 */
571 if (request_module("char-major-%d-%d", SOUND_MAJOR, unit) > 0)
572 request_module("char-major-%d", SOUND_MAJOR);
573
574 spin_lock(&sound_loader_lock);
575 s = __look_for_unit(chain, unit);
576 if (s)
577 new_fops = fops_get(s->unit_fops);
578 }
579 spin_unlock(&sound_loader_lock);
580
581 if (!new_fops)
582 return -ENODEV;
583
584 /*
585 * We rely upon the fact that we can't be unloaded while the
586 * subdriver is there.
587 */
588 replace_fops(file, new_fops);
589
590 if (!file->f_op->open)
591 return -ENODEV;
592
593 return file->f_op->open(inode, file);
594 }
595
596 MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);
597
cleanup_oss_soundcore(void)598 static void cleanup_oss_soundcore(void)
599 {
600 /* We have nothing to really do here - we know the lists must be
601 empty */
602 unregister_chrdev(SOUND_MAJOR, "sound");
603 }
604
init_oss_soundcore(void)605 static int __init init_oss_soundcore(void)
606 {
607 if (preclaim_oss &&
608 register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) < 0) {
609 printk(KERN_ERR "soundcore: sound device already in use.\n");
610 return -EBUSY;
611 }
612
613 return 0;
614 }
615
616 #endif /* CONFIG_SOUND_OSS_CORE */
617
