xref: /openbmc/linux/sound/sound_core.c (revision b6dcefde)
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
21 static inline int init_oss_soundcore(void)	{ return 0; }
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 
32 static char *sound_devnode(struct device *dev, mode_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 
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 
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/smp_lock.h>
108 #include <linux/types.h>
109 #include <linux/kernel.h>
110 #include <linux/sound.h>
111 #include <linux/kmod.h>
112 
113 #define SOUND_STEP 16
114 
115 struct sound_unit
116 {
117 	int unit_minor;
118 	const struct file_operations *unit_fops;
119 	struct sound_unit *next;
120 	char name[32];
121 };
122 
123 #ifdef CONFIG_SOUND_MSNDCLAS
124 extern int msnd_classic_init(void);
125 #endif
126 #ifdef CONFIG_SOUND_MSNDPIN
127 extern int msnd_pinnacle_init(void);
128 #endif
129 
130 /*
131  * By default, OSS sound_core claims full legacy minor range (0-255)
132  * of SOUND_MAJOR to trap open attempts to any sound minor and
133  * requests modules using custom sound-slot/service-* module aliases.
134  * The only benefit of doing this is allowing use of custom module
135  * aliases instead of the standard char-major-* ones.  This behavior
136  * prevents alternative OSS implementation and is scheduled to be
137  * removed.
138  *
139  * CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss kernel
140  * parameter are added to allow distros and developers to try and
141  * switch to alternative implementations without needing to rebuild
142  * the kernel in the meantime.  If preclaim_oss is non-zero, the
143  * kernel will behave the same as before.  All SOUND_MAJOR minors are
144  * preclaimed and the custom module aliases along with standard chrdev
145  * ones are emitted if a missing device is opened.  If preclaim_oss is
146  * zero, sound_core only grabs what's actually in use and for missing
147  * devices only the standard chrdev aliases are requested.
148  *
149  * All these clutters are scheduled to be removed along with
150  * sound-slot/service-* module aliases.  Please take a look at
151  * feature-removal-schedule.txt for details.
152  */
153 #ifdef CONFIG_SOUND_OSS_CORE_PRECLAIM
154 static int preclaim_oss = 1;
155 #else
156 static int preclaim_oss = 0;
157 #endif
158 
159 module_param(preclaim_oss, int, 0444);
160 
161 static int soundcore_open(struct inode *, struct file *);
162 
163 static const struct file_operations soundcore_fops =
164 {
165 	/* We must have an owner or the module locking fails */
166 	.owner	= THIS_MODULE,
167 	.open	= soundcore_open,
168 };
169 
170 /*
171  *	Low level list operator. Scan the ordered list, find a hole and
172  *	join into it. Called with the lock asserted
173  */
174 
175 static int __sound_insert_unit(struct sound_unit * s, struct sound_unit **list, const struct file_operations *fops, int index, int low, int top)
176 {
177 	int n=low;
178 
179 	if (index < 0) {	/* first free */
180 
181 		while (*list && (*list)->unit_minor<n)
182 			list=&((*list)->next);
183 
184 		while(n<top)
185 		{
186 			/* Found a hole ? */
187 			if(*list==NULL || (*list)->unit_minor>n)
188 				break;
189 			list=&((*list)->next);
190 			n+=SOUND_STEP;
191 		}
192 
193 		if(n>=top)
194 			return -ENOENT;
195 	} else {
196 		n = low+(index*16);
197 		while (*list) {
198 			if ((*list)->unit_minor==n)
199 				return -EBUSY;
200 			if ((*list)->unit_minor>n)
201 				break;
202 			list=&((*list)->next);
203 		}
204 	}
205 
206 	/*
207 	 *	Fill it in
208 	 */
209 
210 	s->unit_minor=n;
211 	s->unit_fops=fops;
212 
213 	/*
214 	 *	Link it
215 	 */
216 
217 	s->next=*list;
218 	*list=s;
219 
220 
221 	return n;
222 }
223 
224 /*
225  *	Remove a node from the chain. Called with the lock asserted
226  */
227 
228 static struct sound_unit *__sound_remove_unit(struct sound_unit **list, int unit)
229 {
230 	while(*list)
231 	{
232 		struct sound_unit *p=*list;
233 		if(p->unit_minor==unit)
234 		{
235 			*list=p->next;
236 			return p;
237 		}
238 		list=&(p->next);
239 	}
240 	printk(KERN_ERR "Sound device %d went missing!\n", unit);
241 	return NULL;
242 }
243 
244 /*
245  *	This lock guards the sound loader list.
246  */
247 
248 static DEFINE_SPINLOCK(sound_loader_lock);
249 
250 /*
251  *	Allocate the controlling structure and add it to the sound driver
252  *	list. Acquires locks as needed
253  */
254 
255 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)
256 {
257 	struct sound_unit *s = kmalloc(sizeof(*s), GFP_KERNEL);
258 	int r;
259 
260 	if (!s)
261 		return -ENOMEM;
262 
263 	spin_lock(&sound_loader_lock);
264 retry:
265 	r = __sound_insert_unit(s, list, fops, index, low, top);
266 	spin_unlock(&sound_loader_lock);
267 
268 	if (r < 0)
269 		goto fail;
270 	else if (r < SOUND_STEP)
271 		sprintf(s->name, "sound/%s", name);
272 	else
273 		sprintf(s->name, "sound/%s%d", name, r / SOUND_STEP);
274 
275 	if (!preclaim_oss) {
276 		/*
277 		 * Something else might have grabbed the minor.  If
278 		 * first free slot is requested, rescan with @low set
279 		 * to the next unit; otherwise, -EBUSY.
280 		 */
281 		r = __register_chrdev(SOUND_MAJOR, s->unit_minor, 1, s->name,
282 				      &soundcore_fops);
283 		if (r < 0) {
284 			spin_lock(&sound_loader_lock);
285 			__sound_remove_unit(list, s->unit_minor);
286 			if (index < 0) {
287 				low = s->unit_minor + SOUND_STEP;
288 				goto retry;
289 			}
290 			spin_unlock(&sound_loader_lock);
291 			return -EBUSY;
292 		}
293 	}
294 
295 	device_create(sound_class, dev, MKDEV(SOUND_MAJOR, s->unit_minor),
296 		      NULL, s->name+6);
297 	return s->unit_minor;
298 
299 fail:
300 	kfree(s);
301 	return r;
302 }
303 
304 /*
305  *	Remove a unit. Acquires locks as needed. The drivers MUST have
306  *	completed the removal before their file operations become
307  *	invalid.
308  */
309 
310 static void sound_remove_unit(struct sound_unit **list, int unit)
311 {
312 	struct sound_unit *p;
313 
314 	spin_lock(&sound_loader_lock);
315 	p = __sound_remove_unit(list, unit);
316 	spin_unlock(&sound_loader_lock);
317 	if (p) {
318 		if (!preclaim_oss)
319 			__unregister_chrdev(SOUND_MAJOR, p->unit_minor, 1,
320 					    p->name);
321 		device_destroy(sound_class, MKDEV(SOUND_MAJOR, p->unit_minor));
322 		kfree(p);
323 	}
324 }
325 
326 /*
327  *	Allocations
328  *
329  *	0	*16		Mixers
330  *	1	*8		Sequencers
331  *	2	*16		Midi
332  *	3	*16		DSP
333  *	4	*16		SunDSP
334  *	5	*16		DSP16
335  *	6	--		sndstat (obsolete)
336  *	7	*16		unused
337  *	8	--		alternate sequencer (see above)
338  *	9	*16		raw synthesizer access
339  *	10	*16		unused
340  *	11	*16		unused
341  *	12	*16		unused
342  *	13	*16		unused
343  *	14	*16		unused
344  *	15	*16		unused
345  */
346 
347 static struct sound_unit *chains[SOUND_STEP];
348 
349 /**
350  *	register_sound_special_device - register a special sound node
351  *	@fops: File operations for the driver
352  *	@unit: Unit number to allocate
353  *      @dev: device pointer
354  *
355  *	Allocate a special sound device by minor number from the sound
356  *	subsystem. The allocated number is returned on success. On failure
357  *	a negative error code is returned.
358  */
359 
360 int register_sound_special_device(const struct file_operations *fops, int unit,
361 				  struct device *dev)
362 {
363 	const int chain = unit % SOUND_STEP;
364 	int max_unit = 128 + chain;
365 	const char *name;
366 	char _name[16];
367 
368 	switch (chain) {
369 	    case 0:
370 		name = "mixer";
371 		break;
372 	    case 1:
373 		name = "sequencer";
374 		if (unit >= SOUND_STEP)
375 			goto __unknown;
376 		max_unit = unit + 1;
377 		break;
378 	    case 2:
379 		name = "midi";
380 		break;
381 	    case 3:
382 		name = "dsp";
383 		break;
384 	    case 4:
385 		name = "audio";
386 		break;
387 	    case 8:
388 		name = "sequencer2";
389 		if (unit >= SOUND_STEP)
390 			goto __unknown;
391 		max_unit = unit + 1;
392 		break;
393 	    case 9:
394 		name = "dmmidi";
395 		break;
396 	    case 10:
397 		name = "dmfm";
398 		break;
399 	    case 12:
400 		name = "adsp";
401 		break;
402 	    case 13:
403 		name = "amidi";
404 		break;
405 	    case 14:
406 		name = "admmidi";
407 		break;
408 	    default:
409 	    	{
410 		    __unknown:
411 			sprintf(_name, "unknown%d", chain);
412 		    	if (unit >= SOUND_STEP)
413 		    		strcat(_name, "-");
414 		    	name = _name;
415 		}
416 		break;
417 	}
418 	return sound_insert_unit(&chains[chain], fops, -1, unit, max_unit,
419 				 name, S_IRUSR | S_IWUSR, dev);
420 }
421 
422 EXPORT_SYMBOL(register_sound_special_device);
423 
424 int register_sound_special(const struct file_operations *fops, int unit)
425 {
426 	return register_sound_special_device(fops, unit, NULL);
427 }
428 
429 EXPORT_SYMBOL(register_sound_special);
430 
431 /**
432  *	register_sound_mixer - register a mixer device
433  *	@fops: File operations for the driver
434  *	@dev: Unit number to allocate
435  *
436  *	Allocate a mixer device. Unit is the number of the mixer requested.
437  *	Pass -1 to request the next free mixer unit. On success the allocated
438  *	number is returned, on failure a negative error code is returned.
439  */
440 
441 int register_sound_mixer(const struct file_operations *fops, int dev)
442 {
443 	return sound_insert_unit(&chains[0], fops, dev, 0, 128,
444 				 "mixer", S_IRUSR | S_IWUSR, NULL);
445 }
446 
447 EXPORT_SYMBOL(register_sound_mixer);
448 
449 /**
450  *	register_sound_midi - register a midi device
451  *	@fops: File operations for the driver
452  *	@dev: Unit number to allocate
453  *
454  *	Allocate a midi device. Unit is the number of the midi device requested.
455  *	Pass -1 to request the next free midi unit. On success the allocated
456  *	number is returned, on failure a negative error code is returned.
457  */
458 
459 int register_sound_midi(const struct file_operations *fops, int dev)
460 {
461 	return sound_insert_unit(&chains[2], fops, dev, 2, 130,
462 				 "midi", S_IRUSR | S_IWUSR, NULL);
463 }
464 
465 EXPORT_SYMBOL(register_sound_midi);
466 
467 /*
468  *	DSP's are registered as a triple. Register only one and cheat
469  *	in open - see below.
470  */
471 
472 /**
473  *	register_sound_dsp - register a DSP device
474  *	@fops: File operations for the driver
475  *	@dev: Unit number to allocate
476  *
477  *	Allocate a DSP device. Unit is the number of the DSP requested.
478  *	Pass -1 to request the next free DSP unit. On success the allocated
479  *	number is returned, on failure a negative error code is returned.
480  *
481  *	This function allocates both the audio and dsp device entries together
482  *	and will always allocate them as a matching pair - eg dsp3/audio3
483  */
484 
485 int register_sound_dsp(const struct file_operations *fops, int dev)
486 {
487 	return sound_insert_unit(&chains[3], fops, dev, 3, 131,
488 				 "dsp", S_IWUSR | S_IRUSR, NULL);
489 }
490 
491 EXPORT_SYMBOL(register_sound_dsp);
492 
493 /**
494  *	unregister_sound_special - unregister a special sound device
495  *	@unit: unit number to allocate
496  *
497  *	Release a sound device that was allocated with
498  *	register_sound_special(). The unit passed is the return value from
499  *	the register function.
500  */
501 
502 
503 void unregister_sound_special(int unit)
504 {
505 	sound_remove_unit(&chains[unit % SOUND_STEP], unit);
506 }
507 
508 EXPORT_SYMBOL(unregister_sound_special);
509 
510 /**
511  *	unregister_sound_mixer - unregister a mixer
512  *	@unit: unit number to allocate
513  *
514  *	Release a sound device that was allocated with register_sound_mixer().
515  *	The unit passed is the return value from the register function.
516  */
517 
518 void unregister_sound_mixer(int unit)
519 {
520 	sound_remove_unit(&chains[0], unit);
521 }
522 
523 EXPORT_SYMBOL(unregister_sound_mixer);
524 
525 /**
526  *	unregister_sound_midi - unregister a midi device
527  *	@unit: unit number to allocate
528  *
529  *	Release a sound device that was allocated with register_sound_midi().
530  *	The unit passed is the return value from the register function.
531  */
532 
533 void unregister_sound_midi(int unit)
534 {
535 	sound_remove_unit(&chains[2], unit);
536 }
537 
538 EXPORT_SYMBOL(unregister_sound_midi);
539 
540 /**
541  *	unregister_sound_dsp - unregister a DSP device
542  *	@unit: unit number to allocate
543  *
544  *	Release a sound device that was allocated with register_sound_dsp().
545  *	The unit passed is the return value from the register function.
546  *
547  *	Both of the allocated units are released together automatically.
548  */
549 
550 void unregister_sound_dsp(int unit)
551 {
552 	sound_remove_unit(&chains[3], unit);
553 }
554 
555 
556 EXPORT_SYMBOL(unregister_sound_dsp);
557 
558 static struct sound_unit *__look_for_unit(int chain, int unit)
559 {
560 	struct sound_unit *s;
561 
562 	s=chains[chain];
563 	while(s && s->unit_minor <= unit)
564 	{
565 		if(s->unit_minor==unit)
566 			return s;
567 		s=s->next;
568 	}
569 	return NULL;
570 }
571 
572 static int soundcore_open(struct inode *inode, struct file *file)
573 {
574 	int chain;
575 	int unit = iminor(inode);
576 	struct sound_unit *s;
577 	const struct file_operations *new_fops = NULL;
578 
579 	lock_kernel ();
580 
581 	chain=unit&0x0F;
582 	if(chain==4 || chain==5)	/* dsp/audio/dsp16 */
583 	{
584 		unit&=0xF0;
585 		unit|=3;
586 		chain=3;
587 	}
588 
589 	spin_lock(&sound_loader_lock);
590 	s = __look_for_unit(chain, unit);
591 	if (s)
592 		new_fops = fops_get(s->unit_fops);
593 	if (preclaim_oss && !new_fops) {
594 		spin_unlock(&sound_loader_lock);
595 
596 		/*
597 		 *  Please, don't change this order or code.
598 		 *  For ALSA slot means soundcard and OSS emulation code
599 		 *  comes as add-on modules which aren't depend on
600 		 *  ALSA toplevel modules for soundcards, thus we need
601 		 *  load them at first.	  [Jaroslav Kysela <perex@jcu.cz>]
602 		 */
603 		request_module("sound-slot-%i", unit>>4);
604 		request_module("sound-service-%i-%i", unit>>4, chain);
605 
606 		/*
607 		 * sound-slot/service-* module aliases are scheduled
608 		 * for removal in favor of the standard char-major-*
609 		 * module aliases.  For the time being, generate both
610 		 * the legacy and standard module aliases to ease
611 		 * transition.
612 		 */
613 		if (request_module("char-major-%d-%d", SOUND_MAJOR, unit) > 0)
614 			request_module("char-major-%d", SOUND_MAJOR);
615 
616 		spin_lock(&sound_loader_lock);
617 		s = __look_for_unit(chain, unit);
618 		if (s)
619 			new_fops = fops_get(s->unit_fops);
620 	}
621 	if (new_fops) {
622 		/*
623 		 * We rely upon the fact that we can't be unloaded while the
624 		 * subdriver is there, so if ->open() is successful we can
625 		 * safely drop the reference counter and if it is not we can
626 		 * revert to old ->f_op. Ugly, indeed, but that's the cost of
627 		 * switching ->f_op in the first place.
628 		 */
629 		int err = 0;
630 		const struct file_operations *old_fops = file->f_op;
631 		file->f_op = new_fops;
632 		spin_unlock(&sound_loader_lock);
633 		if(file->f_op->open)
634 			err = file->f_op->open(inode,file);
635 		if (err) {
636 			fops_put(file->f_op);
637 			file->f_op = fops_get(old_fops);
638 		}
639 		fops_put(old_fops);
640 		unlock_kernel();
641 		return err;
642 	}
643 	spin_unlock(&sound_loader_lock);
644 	unlock_kernel();
645 	return -ENODEV;
646 }
647 
648 MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);
649 
650 static void cleanup_oss_soundcore(void)
651 {
652 	/* We have nothing to really do here - we know the lists must be
653 	   empty */
654 	unregister_chrdev(SOUND_MAJOR, "sound");
655 }
656 
657 static int __init init_oss_soundcore(void)
658 {
659 	if (preclaim_oss &&
660 	    register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) == -1) {
661 		printk(KERN_ERR "soundcore: sound device already in use.\n");
662 		return -EBUSY;
663 	}
664 
665 	return 0;
666 }
667 
668 #endif /* CONFIG_SOUND_OSS_CORE */
669