1 /*
2 * Sound core. This file is composed of two parts. sound_class
3 * which is common to both OSS and ALSA and OSS sound core which
4 * is used OSS or emulation of it.
5 */
6
7 /*
8 * First, the common part.
9 */
10 #include <linux/module.h>
11 #include <linux/device.h>
12 #include <linux/err.h>
13 #include <linux/kdev_t.h>
14 #include <linux/major.h>
15 #include <sound/core.h>
16
17 #ifdef CONFIG_SOUND_OSS_CORE
18 static int __init init_oss_soundcore(void);
19 static void cleanup_oss_soundcore(void);
20 #else
init_oss_soundcore(void)21 static inline int init_oss_soundcore(void) { return 0; }
cleanup_oss_soundcore(void)22 static inline void cleanup_oss_soundcore(void) { }
23 #endif
24
25 struct class *sound_class;
26 EXPORT_SYMBOL(sound_class);
27
28 MODULE_DESCRIPTION("Core sound module");
29 MODULE_AUTHOR("Alan Cox");
30 MODULE_LICENSE("GPL");
31
sound_devnode(struct device * dev,umode_t * mode)32 static char *sound_devnode(struct device *dev, umode_t *mode)
33 {
34 if (MAJOR(dev->devt) == SOUND_MAJOR)
35 return NULL;
36 return kasprintf(GFP_KERNEL, "snd/%s", dev_name(dev));
37 }
38
init_soundcore(void)39 static int __init init_soundcore(void)
40 {
41 int rc;
42
43 rc = init_oss_soundcore();
44 if (rc)
45 return rc;
46
47 sound_class = class_create(THIS_MODULE, "sound");
48 if (IS_ERR(sound_class)) {
49 cleanup_oss_soundcore();
50 return PTR_ERR(sound_class);
51 }
52
53 sound_class->devnode = sound_devnode;
54
55 return 0;
56 }
57
cleanup_soundcore(void)58 static void __exit cleanup_soundcore(void)
59 {
60 cleanup_oss_soundcore();
61 class_destroy(sound_class);
62 }
63
64 subsys_initcall(init_soundcore);
65 module_exit(cleanup_soundcore);
66
67
68 #ifdef CONFIG_SOUND_OSS_CORE
69 /*
70 * OSS sound core handling. Breaks out sound functions to submodules
71 *
72 * Author: Alan Cox <alan@lxorguk.ukuu.org.uk>
73 *
74 * Fixes:
75 *
76 *
77 * This program is free software; you can redistribute it and/or
78 * modify it under the terms of the GNU General Public License
79 * as published by the Free Software Foundation; either version
80 * 2 of the License, or (at your option) any later version.
81 *
82 * --------------------
83 *
84 * Top level handler for the sound subsystem. Various devices can
85 * plug into this. The fact they don't all go via OSS doesn't mean
86 * they don't have to implement the OSS API. There is a lot of logic
87 * to keeping much of the OSS weight out of the code in a compatibility
88 * module, but it's up to the driver to rember to load it...
89 *
90 * The code provides a set of functions for registration of devices
91 * by type. This is done rather than providing a single call so that
92 * we can hide any future changes in the internals (eg when we go to
93 * 32bit dev_t) from the modules and their interface.
94 *
95 * Secondly we need to allocate the dsp, dsp16 and audio devices as
96 * one. Thus we misuse the chains a bit to simplify this.
97 *
98 * Thirdly to make it more fun and for 2.3.x and above we do all
99 * of this using fine grained locking.
100 *
101 * FIXME: we have to resolve modules and fine grained load/unload
102 * locking at some point in 2.3.x.
103 */
104
105 #include <linux/init.h>
106 #include <linux/slab.h>
107 #include <linux/types.h>
108 #include <linux/kernel.h>
109 #include <linux/sound.h>
110 #include <linux/kmod.h>
111
112 #define SOUND_STEP 16
113
114 struct sound_unit
115 {
116 int unit_minor;
117 const struct file_operations *unit_fops;
118 struct sound_unit *next;
119 char name[32];
120 };
121
122 /*
123 * By default, OSS sound_core claims full legacy minor range (0-255)
124 * of SOUND_MAJOR to trap open attempts to any sound minor and
125 * requests modules using custom sound-slot/service-* module aliases.
126 * The only benefit of doing this is allowing use of custom module
127 * aliases instead of the standard char-major-* ones. This behavior
128 * prevents alternative OSS implementation and is scheduled to be
129 * removed.
130 *
131 * CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss kernel
132 * parameter are added to allow distros and developers to try and
133 * switch to alternative implementations without needing to rebuild
134 * the kernel in the meantime. If preclaim_oss is non-zero, the
135 * kernel will behave the same as before. All SOUND_MAJOR minors are
136 * preclaimed and the custom module aliases along with standard chrdev
137 * ones are emitted if a missing device is opened. If preclaim_oss is
138 * zero, sound_core only grabs what's actually in use and for missing
139 * devices only the standard chrdev aliases are requested.
140 *
141 * All these clutters are scheduled to be removed along with
142 * sound-slot/service-* module aliases.
143 */
144 #ifdef CONFIG_SOUND_OSS_CORE_PRECLAIM
145 static int preclaim_oss = 1;
146 #else
147 static int preclaim_oss = 0;
148 #endif
149
150 module_param(preclaim_oss, int, 0444);
151
152 static int soundcore_open(struct inode *, struct file *);
153
154 static const struct file_operations soundcore_fops =
155 {
156 /* We must have an owner or the module locking fails */
157 .owner = THIS_MODULE,
158 .open = soundcore_open,
159 .llseek = noop_llseek,
160 };
161
162 /*
163 * Low level list operator. Scan the ordered list, find a hole and
164 * join into it. Called with the lock asserted
165 */
166
__sound_insert_unit(struct sound_unit * s,struct sound_unit ** list,const struct file_operations * fops,int index,int low,int top)167 static int __sound_insert_unit(struct sound_unit * s, struct sound_unit **list, const struct file_operations *fops, int index, int low, int top)
168 {
169 int n=low;
170
171 if (index < 0) { /* first free */
172
173 while (*list && (*list)->unit_minor<n)
174 list=&((*list)->next);
175
176 while(n<top)
177 {
178 /* Found a hole ? */
179 if(*list==NULL || (*list)->unit_minor>n)
180 break;
181 list=&((*list)->next);
182 n+=SOUND_STEP;
183 }
184
185 if(n>=top)
186 return -ENOENT;
187 } else {
188 n = low+(index*16);
189 while (*list) {
190 if ((*list)->unit_minor==n)
191 return -EBUSY;
192 if ((*list)->unit_minor>n)
193 break;
194 list=&((*list)->next);
195 }
196 }
197
198 /*
199 * Fill it in
200 */
201
202 s->unit_minor=n;
203 s->unit_fops=fops;
204
205 /*
206 * Link it
207 */
208
209 s->next=*list;
210 *list=s;
211
212
213 return n;
214 }
215
216 /*
217 * Remove a node from the chain. Called with the lock asserted
218 */
219
__sound_remove_unit(struct sound_unit ** list,int unit)220 static struct sound_unit *__sound_remove_unit(struct sound_unit **list, int unit)
221 {
222 while(*list)
223 {
224 struct sound_unit *p=*list;
225 if(p->unit_minor==unit)
226 {
227 *list=p->next;
228 return p;
229 }
230 list=&(p->next);
231 }
232 printk(KERN_ERR "Sound device %d went missing!\n", unit);
233 return NULL;
234 }
235
236 /*
237 * This lock guards the sound loader list.
238 */
239
240 static DEFINE_SPINLOCK(sound_loader_lock);
241
242 /*
243 * Allocate the controlling structure and add it to the sound driver
244 * list. Acquires locks as needed
245 */
246
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)247 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)
248 {
249 struct sound_unit *s = kmalloc(sizeof(*s), GFP_KERNEL);
250 int r;
251
252 if (!s)
253 return -ENOMEM;
254
255 spin_lock(&sound_loader_lock);
256 retry:
257 r = __sound_insert_unit(s, list, fops, index, low, top);
258 spin_unlock(&sound_loader_lock);
259
260 if (r < 0)
261 goto fail;
262 else if (r < SOUND_STEP)
263 sprintf(s->name, "sound/%s", name);
264 else
265 sprintf(s->name, "sound/%s%d", name, r / SOUND_STEP);
266
267 if (!preclaim_oss) {
268 /*
269 * Something else might have grabbed the minor. If
270 * first free slot is requested, rescan with @low set
271 * to the next unit; otherwise, -EBUSY.
272 */
273 r = __register_chrdev(SOUND_MAJOR, s->unit_minor, 1, s->name,
274 &soundcore_fops);
275 if (r < 0) {
276 spin_lock(&sound_loader_lock);
277 __sound_remove_unit(list, s->unit_minor);
278 if (index < 0) {
279 low = s->unit_minor + SOUND_STEP;
280 goto retry;
281 }
282 spin_unlock(&sound_loader_lock);
283 return -EBUSY;
284 }
285 }
286
287 device_create(sound_class, dev, MKDEV(SOUND_MAJOR, s->unit_minor),
288 NULL, "%s", s->name+6);
289 return s->unit_minor;
290
291 fail:
292 kfree(s);
293 return r;
294 }
295
296 /*
297 * Remove a unit. Acquires locks as needed. The drivers MUST have
298 * completed the removal before their file operations become
299 * invalid.
300 */
301
sound_remove_unit(struct sound_unit ** list,int unit)302 static void sound_remove_unit(struct sound_unit **list, int unit)
303 {
304 struct sound_unit *p;
305
306 spin_lock(&sound_loader_lock);
307 p = __sound_remove_unit(list, unit);
308 spin_unlock(&sound_loader_lock);
309 if (p) {
310 if (!preclaim_oss)
311 __unregister_chrdev(SOUND_MAJOR, p->unit_minor, 1,
312 p->name);
313 device_destroy(sound_class, MKDEV(SOUND_MAJOR, p->unit_minor));
314 kfree(p);
315 }
316 }
317
318 /*
319 * Allocations
320 *
321 * 0 *16 Mixers
322 * 1 *8 Sequencers
323 * 2 *16 Midi
324 * 3 *16 DSP
325 * 4 *16 SunDSP
326 * 5 *16 DSP16
327 * 6 -- sndstat (obsolete)
328 * 7 *16 unused
329 * 8 -- alternate sequencer (see above)
330 * 9 *16 raw synthesizer access
331 * 10 *16 unused
332 * 11 *16 unused
333 * 12 *16 unused
334 * 13 *16 unused
335 * 14 *16 unused
336 * 15 *16 unused
337 */
338
339 static struct sound_unit *chains[SOUND_STEP];
340
341 /**
342 * register_sound_special_device - register a special sound node
343 * @fops: File operations for the driver
344 * @unit: Unit number to allocate
345 * @dev: device pointer
346 *
347 * Allocate a special sound device by minor number from the sound
348 * subsystem.
349 *
350 * Return: The allocated number is returned on success. On failure,
351 * a negative error code is returned.
352 */
353
register_sound_special_device(const struct file_operations * fops,int unit,struct device * dev)354 int register_sound_special_device(const struct file_operations *fops, int unit,
355 struct device *dev)
356 {
357 const int chain = unit % SOUND_STEP;
358 int max_unit = 256;
359 const char *name;
360 char _name[16];
361
362 switch (chain) {
363 case 0:
364 name = "mixer";
365 break;
366 case 1:
367 name = "sequencer";
368 if (unit >= SOUND_STEP)
369 goto __unknown;
370 max_unit = unit + 1;
371 break;
372 case 2:
373 name = "midi";
374 break;
375 case 3:
376 name = "dsp";
377 break;
378 case 4:
379 name = "audio";
380 break;
381 case 5:
382 name = "dspW";
383 break;
384 case 8:
385 name = "sequencer2";
386 if (unit >= SOUND_STEP)
387 goto __unknown;
388 max_unit = unit + 1;
389 break;
390 case 9:
391 name = "dmmidi";
392 break;
393 case 10:
394 name = "dmfm";
395 break;
396 case 12:
397 name = "adsp";
398 break;
399 case 13:
400 name = "amidi";
401 break;
402 case 14:
403 name = "admmidi";
404 break;
405 default:
406 {
407 __unknown:
408 sprintf(_name, "unknown%d", chain);
409 if (unit >= SOUND_STEP)
410 strcat(_name, "-");
411 name = _name;
412 }
413 break;
414 }
415 return sound_insert_unit(&chains[chain], fops, -1, unit, max_unit,
416 name, 0600, dev);
417 }
418
419 EXPORT_SYMBOL(register_sound_special_device);
420
register_sound_special(const struct file_operations * fops,int unit)421 int register_sound_special(const struct file_operations *fops, int unit)
422 {
423 return register_sound_special_device(fops, unit, NULL);
424 }
425
426 EXPORT_SYMBOL(register_sound_special);
427
428 /**
429 * register_sound_mixer - register a mixer device
430 * @fops: File operations for the driver
431 * @dev: Unit number to allocate
432 *
433 * Allocate a mixer device. Unit is the number of the mixer requested.
434 * Pass -1 to request the next free mixer unit.
435 *
436 * Return: On success, the allocated number is returned. On failure,
437 * a negative error code is returned.
438 */
439
register_sound_mixer(const struct file_operations * fops,int dev)440 int register_sound_mixer(const struct file_operations *fops, int dev)
441 {
442 return sound_insert_unit(&chains[0], fops, dev, 0, 128,
443 "mixer", 0600, NULL);
444 }
445
446 EXPORT_SYMBOL(register_sound_mixer);
447
448 /*
449 * DSP's are registered as a triple. Register only one and cheat
450 * in open - see below.
451 */
452
453 /**
454 * register_sound_dsp - register a DSP device
455 * @fops: File operations for the driver
456 * @dev: Unit number to allocate
457 *
458 * Allocate a DSP device. Unit is the number of the DSP requested.
459 * Pass -1 to request the next free DSP unit.
460 *
461 * This function allocates both the audio and dsp device entries together
462 * and will always allocate them as a matching pair - eg dsp3/audio3
463 *
464 * Return: On success, the allocated number is returned. On failure,
465 * a negative error code is returned.
466 */
467
register_sound_dsp(const struct file_operations * fops,int dev)468 int register_sound_dsp(const struct file_operations *fops, int dev)
469 {
470 return sound_insert_unit(&chains[3], fops, dev, 3, 131,
471 "dsp", 0600, NULL);
472 }
473
474 EXPORT_SYMBOL(register_sound_dsp);
475
476 /**
477 * unregister_sound_special - unregister a special sound device
478 * @unit: unit number to allocate
479 *
480 * Release a sound device that was allocated with
481 * register_sound_special(). The unit passed is the return value from
482 * the register function.
483 */
484
485
unregister_sound_special(int unit)486 void unregister_sound_special(int unit)
487 {
488 sound_remove_unit(&chains[unit % SOUND_STEP], unit);
489 }
490
491 EXPORT_SYMBOL(unregister_sound_special);
492
493 /**
494 * unregister_sound_mixer - unregister a mixer
495 * @unit: unit number to allocate
496 *
497 * Release a sound device that was allocated with register_sound_mixer().
498 * The unit passed is the return value from the register function.
499 */
500
unregister_sound_mixer(int unit)501 void unregister_sound_mixer(int unit)
502 {
503 sound_remove_unit(&chains[0], unit);
504 }
505
506 EXPORT_SYMBOL(unregister_sound_mixer);
507
508 /**
509 * unregister_sound_dsp - unregister a DSP device
510 * @unit: unit number to allocate
511 *
512 * Release a sound device that was allocated with register_sound_dsp().
513 * The unit passed is the return value from the register function.
514 *
515 * Both of the allocated units are released together automatically.
516 */
517
unregister_sound_dsp(int unit)518 void unregister_sound_dsp(int unit)
519 {
520 sound_remove_unit(&chains[3], unit);
521 }
522
523
524 EXPORT_SYMBOL(unregister_sound_dsp);
525
__look_for_unit(int chain,int unit)526 static struct sound_unit *__look_for_unit(int chain, int unit)
527 {
528 struct sound_unit *s;
529
530 s=chains[chain];
531 while(s && s->unit_minor <= unit)
532 {
533 if(s->unit_minor==unit)
534 return s;
535 s=s->next;
536 }
537 return NULL;
538 }
539
soundcore_open(struct inode * inode,struct file * file)540 static int soundcore_open(struct inode *inode, struct file *file)
541 {
542 int chain;
543 int unit = iminor(inode);
544 struct sound_unit *s;
545 const struct file_operations *new_fops = NULL;
546
547 chain=unit&0x0F;
548 if(chain==4 || chain==5) /* dsp/audio/dsp16 */
549 {
550 unit&=0xF0;
551 unit|=3;
552 chain=3;
553 }
554
555 spin_lock(&sound_loader_lock);
556 s = __look_for_unit(chain, unit);
557 if (s)
558 new_fops = fops_get(s->unit_fops);
559 if (preclaim_oss && !new_fops) {
560 spin_unlock(&sound_loader_lock);
561
562 /*
563 * Please, don't change this order or code.
564 * For ALSA slot means soundcard and OSS emulation code
565 * comes as add-on modules which aren't depend on
566 * ALSA toplevel modules for soundcards, thus we need
567 * load them at first. [Jaroslav Kysela <perex@jcu.cz>]
568 */
569 request_module("sound-slot-%i", unit>>4);
570 request_module("sound-service-%i-%i", unit>>4, chain);
571
572 /*
573 * sound-slot/service-* module aliases are scheduled
574 * for removal in favor of the standard char-major-*
575 * module aliases. For the time being, generate both
576 * the legacy and standard module aliases to ease
577 * transition.
578 */
579 if (request_module("char-major-%d-%d", SOUND_MAJOR, unit) > 0)
580 request_module("char-major-%d", SOUND_MAJOR);
581
582 spin_lock(&sound_loader_lock);
583 s = __look_for_unit(chain, unit);
584 if (s)
585 new_fops = fops_get(s->unit_fops);
586 }
587 spin_unlock(&sound_loader_lock);
588 if (new_fops) {
589 /*
590 * We rely upon the fact that we can't be unloaded while the
591 * subdriver is there.
592 */
593 int err = 0;
594 replace_fops(file, new_fops);
595
596 if (file->f_op->open)
597 err = file->f_op->open(inode,file);
598
599 return err;
600 }
601 return -ENODEV;
602 }
603
604 MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);
605
cleanup_oss_soundcore(void)606 static void cleanup_oss_soundcore(void)
607 {
608 /* We have nothing to really do here - we know the lists must be
609 empty */
610 unregister_chrdev(SOUND_MAJOR, "sound");
611 }
612
init_oss_soundcore(void)613 static int __init init_oss_soundcore(void)
614 {
615 if (preclaim_oss &&
616 register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) < 0) {
617 printk(KERN_ERR "soundcore: sound device already in use.\n");
618 return -EBUSY;
619 }
620
621 return 0;
622 }
623
624 #endif /* CONFIG_SOUND_OSS_CORE */
625
