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