xref: /openbmc/linux/sound/sound_core.c (revision 22246614)
1 /*
2  *	Sound core handling. Breaks out sound functions to submodules
3  *
4  *	Author:		Alan Cox <alan.cox@linux.org>
5  *
6  *	Fixes:
7  *
8  *
9  *	This program is free software; you can redistribute it and/or
10  *	modify it under the terms of the GNU General Public License
11  *	as published by the Free Software Foundation; either version
12  *	2 of the License, or (at your option) any later version.
13  *
14  *                         --------------------
15  *
16  *	Top level handler for the sound subsystem. Various devices can
17  *	plug into this. The fact they don't all go via OSS doesn't mean
18  *	they don't have to implement the OSS API. There is a lot of logic
19  *	to keeping much of the OSS weight out of the code in a compatibility
20  *	module, but it's up to the driver to rember to load it...
21  *
22  *	The code provides a set of functions for registration of devices
23  *	by type. This is done rather than providing a single call so that
24  *	we can hide any future changes in the internals (eg when we go to
25  *	32bit dev_t) from the modules and their interface.
26  *
27  *	Secondly we need to allocate the dsp, dsp16 and audio devices as
28  *	one. Thus we misuse the chains a bit to simplify this.
29  *
30  *	Thirdly to make it more fun and for 2.3.x and above we do all
31  *	of this using fine grained locking.
32  *
33  *	FIXME: we have to resolve modules and fine grained load/unload
34  *	locking at some point in 2.3.x.
35  */
36 
37 #include <linux/module.h>
38 #include <linux/init.h>
39 #include <linux/slab.h>
40 #include <linux/types.h>
41 #include <linux/kernel.h>
42 #include <linux/fs.h>
43 #include <linux/sound.h>
44 #include <linux/major.h>
45 #include <linux/kmod.h>
46 #include <linux/device.h>
47 
48 #define SOUND_STEP 16
49 
50 
51 struct sound_unit
52 {
53 	int unit_minor;
54 	const struct file_operations *unit_fops;
55 	struct sound_unit *next;
56 	char name[32];
57 };
58 
59 #ifdef CONFIG_SOUND_MSNDCLAS
60 extern int msnd_classic_init(void);
61 #endif
62 #ifdef CONFIG_SOUND_MSNDPIN
63 extern int msnd_pinnacle_init(void);
64 #endif
65 
66 struct class *sound_class;
67 EXPORT_SYMBOL(sound_class);
68 
69 /*
70  *	Low level list operator. Scan the ordered list, find a hole and
71  *	join into it. Called with the lock asserted
72  */
73 
74 static int __sound_insert_unit(struct sound_unit * s, struct sound_unit **list, const struct file_operations *fops, int index, int low, int top)
75 {
76 	int n=low;
77 
78 	if (index < 0) {	/* first free */
79 
80 		while (*list && (*list)->unit_minor<n)
81 			list=&((*list)->next);
82 
83 		while(n<top)
84 		{
85 			/* Found a hole ? */
86 			if(*list==NULL || (*list)->unit_minor>n)
87 				break;
88 			list=&((*list)->next);
89 			n+=SOUND_STEP;
90 		}
91 
92 		if(n>=top)
93 			return -ENOENT;
94 	} else {
95 		n = low+(index*16);
96 		while (*list) {
97 			if ((*list)->unit_minor==n)
98 				return -EBUSY;
99 			if ((*list)->unit_minor>n)
100 				break;
101 			list=&((*list)->next);
102 		}
103 	}
104 
105 	/*
106 	 *	Fill it in
107 	 */
108 
109 	s->unit_minor=n;
110 	s->unit_fops=fops;
111 
112 	/*
113 	 *	Link it
114 	 */
115 
116 	s->next=*list;
117 	*list=s;
118 
119 
120 	return n;
121 }
122 
123 /*
124  *	Remove a node from the chain. Called with the lock asserted
125  */
126 
127 static struct sound_unit *__sound_remove_unit(struct sound_unit **list, int unit)
128 {
129 	while(*list)
130 	{
131 		struct sound_unit *p=*list;
132 		if(p->unit_minor==unit)
133 		{
134 			*list=p->next;
135 			return p;
136 		}
137 		list=&(p->next);
138 	}
139 	printk(KERN_ERR "Sound device %d went missing!\n", unit);
140 	return NULL;
141 }
142 
143 /*
144  *	This lock guards the sound loader list.
145  */
146 
147 static DEFINE_SPINLOCK(sound_loader_lock);
148 
149 /*
150  *	Allocate the controlling structure and add it to the sound driver
151  *	list. Acquires locks as needed
152  */
153 
154 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)
155 {
156 	struct sound_unit *s = kmalloc(sizeof(*s), GFP_KERNEL);
157 	int r;
158 
159 	if (!s)
160 		return -ENOMEM;
161 
162 	spin_lock(&sound_loader_lock);
163 	r = __sound_insert_unit(s, list, fops, index, low, top);
164 	spin_unlock(&sound_loader_lock);
165 
166 	if (r < 0)
167 		goto fail;
168 	else if (r < SOUND_STEP)
169 		sprintf(s->name, "sound/%s", name);
170 	else
171 		sprintf(s->name, "sound/%s%d", name, r / SOUND_STEP);
172 
173 	device_create(sound_class, dev, MKDEV(SOUND_MAJOR, s->unit_minor),
174 		      s->name+6);
175 	return r;
176 
177  fail:
178 	kfree(s);
179 	return r;
180 }
181 
182 /*
183  *	Remove a unit. Acquires locks as needed. The drivers MUST have
184  *	completed the removal before their file operations become
185  *	invalid.
186  */
187 
188 static void sound_remove_unit(struct sound_unit **list, int unit)
189 {
190 	struct sound_unit *p;
191 
192 	spin_lock(&sound_loader_lock);
193 	p = __sound_remove_unit(list, unit);
194 	spin_unlock(&sound_loader_lock);
195 	if (p) {
196 		device_destroy(sound_class, MKDEV(SOUND_MAJOR, p->unit_minor));
197 		kfree(p);
198 	}
199 }
200 
201 /*
202  *	Allocations
203  *
204  *	0	*16		Mixers
205  *	1	*8		Sequencers
206  *	2	*16		Midi
207  *	3	*16		DSP
208  *	4	*16		SunDSP
209  *	5	*16		DSP16
210  *	6	--		sndstat (obsolete)
211  *	7	*16		unused
212  *	8	--		alternate sequencer (see above)
213  *	9	*16		raw synthesizer access
214  *	10	*16		unused
215  *	11	*16		unused
216  *	12	*16		unused
217  *	13	*16		unused
218  *	14	*16		unused
219  *	15	*16		unused
220  */
221 
222 static struct sound_unit *chains[SOUND_STEP];
223 
224 /**
225  *	register_sound_special_device - register a special sound node
226  *	@fops: File operations for the driver
227  *	@unit: Unit number to allocate
228  *      @dev: device pointer
229  *
230  *	Allocate a special sound device by minor number from the sound
231  *	subsystem. The allocated number is returned on succes. On failure
232  *	a negative error code is returned.
233  */
234 
235 int register_sound_special_device(const struct file_operations *fops, int unit,
236 				  struct device *dev)
237 {
238 	const int chain = unit % SOUND_STEP;
239 	int max_unit = 128 + chain;
240 	const char *name;
241 	char _name[16];
242 
243 	switch (chain) {
244 	    case 0:
245 		name = "mixer";
246 		break;
247 	    case 1:
248 		name = "sequencer";
249 		if (unit >= SOUND_STEP)
250 			goto __unknown;
251 		max_unit = unit + 1;
252 		break;
253 	    case 2:
254 		name = "midi";
255 		break;
256 	    case 3:
257 		name = "dsp";
258 		break;
259 	    case 4:
260 		name = "audio";
261 		break;
262 	    case 8:
263 		name = "sequencer2";
264 		if (unit >= SOUND_STEP)
265 			goto __unknown;
266 		max_unit = unit + 1;
267 		break;
268 	    case 9:
269 		name = "dmmidi";
270 		break;
271 	    case 10:
272 		name = "dmfm";
273 		break;
274 	    case 12:
275 		name = "adsp";
276 		break;
277 	    case 13:
278 		name = "amidi";
279 		break;
280 	    case 14:
281 		name = "admmidi";
282 		break;
283 	    default:
284 	    	{
285 		    __unknown:
286 			sprintf(_name, "unknown%d", chain);
287 		    	if (unit >= SOUND_STEP)
288 		    		strcat(_name, "-");
289 		    	name = _name;
290 		}
291 		break;
292 	}
293 	return sound_insert_unit(&chains[chain], fops, -1, unit, max_unit,
294 				 name, S_IRUSR | S_IWUSR, dev);
295 }
296 
297 EXPORT_SYMBOL(register_sound_special_device);
298 
299 int register_sound_special(const struct file_operations *fops, int unit)
300 {
301 	return register_sound_special_device(fops, unit, NULL);
302 }
303 
304 EXPORT_SYMBOL(register_sound_special);
305 
306 /**
307  *	register_sound_mixer - register a mixer device
308  *	@fops: File operations for the driver
309  *	@dev: Unit number to allocate
310  *
311  *	Allocate a mixer device. Unit is the number of the mixer requested.
312  *	Pass -1 to request the next free mixer unit. On success the allocated
313  *	number is returned, on failure a negative error code is returned.
314  */
315 
316 int register_sound_mixer(const struct file_operations *fops, int dev)
317 {
318 	return sound_insert_unit(&chains[0], fops, dev, 0, 128,
319 				 "mixer", S_IRUSR | S_IWUSR, NULL);
320 }
321 
322 EXPORT_SYMBOL(register_sound_mixer);
323 
324 /**
325  *	register_sound_midi - register a midi device
326  *	@fops: File operations for the driver
327  *	@dev: Unit number to allocate
328  *
329  *	Allocate a midi device. Unit is the number of the midi device requested.
330  *	Pass -1 to request the next free midi unit. On success the allocated
331  *	number is returned, on failure a negative error code is returned.
332  */
333 
334 int register_sound_midi(const struct file_operations *fops, int dev)
335 {
336 	return sound_insert_unit(&chains[2], fops, dev, 2, 130,
337 				 "midi", S_IRUSR | S_IWUSR, NULL);
338 }
339 
340 EXPORT_SYMBOL(register_sound_midi);
341 
342 /*
343  *	DSP's are registered as a triple. Register only one and cheat
344  *	in open - see below.
345  */
346 
347 /**
348  *	register_sound_dsp - register a DSP device
349  *	@fops: File operations for the driver
350  *	@dev: Unit number to allocate
351  *
352  *	Allocate a DSP device. Unit is the number of the DSP requested.
353  *	Pass -1 to request the next free DSP unit. On success the allocated
354  *	number is returned, on failure a negative error code is returned.
355  *
356  *	This function allocates both the audio and dsp device entries together
357  *	and will always allocate them as a matching pair - eg dsp3/audio3
358  */
359 
360 int register_sound_dsp(const struct file_operations *fops, int dev)
361 {
362 	return sound_insert_unit(&chains[3], fops, dev, 3, 131,
363 				 "dsp", S_IWUSR | S_IRUSR, NULL);
364 }
365 
366 EXPORT_SYMBOL(register_sound_dsp);
367 
368 /**
369  *	unregister_sound_special - unregister a special sound device
370  *	@unit: unit number to allocate
371  *
372  *	Release a sound device that was allocated with
373  *	register_sound_special(). The unit passed is the return value from
374  *	the register function.
375  */
376 
377 
378 void unregister_sound_special(int unit)
379 {
380 	sound_remove_unit(&chains[unit % SOUND_STEP], unit);
381 }
382 
383 EXPORT_SYMBOL(unregister_sound_special);
384 
385 /**
386  *	unregister_sound_mixer - unregister a mixer
387  *	@unit: unit number to allocate
388  *
389  *	Release a sound device that was allocated with register_sound_mixer().
390  *	The unit passed is the return value from the register function.
391  */
392 
393 void unregister_sound_mixer(int unit)
394 {
395 	sound_remove_unit(&chains[0], unit);
396 }
397 
398 EXPORT_SYMBOL(unregister_sound_mixer);
399 
400 /**
401  *	unregister_sound_midi - unregister a midi device
402  *	@unit: unit number to allocate
403  *
404  *	Release a sound device that was allocated with register_sound_midi().
405  *	The unit passed is the return value from the register function.
406  */
407 
408 void unregister_sound_midi(int unit)
409 {
410 	return sound_remove_unit(&chains[2], unit);
411 }
412 
413 EXPORT_SYMBOL(unregister_sound_midi);
414 
415 /**
416  *	unregister_sound_dsp - unregister a DSP device
417  *	@unit: unit number to allocate
418  *
419  *	Release a sound device that was allocated with register_sound_dsp().
420  *	The unit passed is the return value from the register function.
421  *
422  *	Both of the allocated units are released together automatically.
423  */
424 
425 void unregister_sound_dsp(int unit)
426 {
427 	return sound_remove_unit(&chains[3], unit);
428 }
429 
430 
431 EXPORT_SYMBOL(unregister_sound_dsp);
432 
433 /*
434  *	Now our file operations
435  */
436 
437 static int soundcore_open(struct inode *, struct file *);
438 
439 static const struct file_operations soundcore_fops=
440 {
441 	/* We must have an owner or the module locking fails */
442 	.owner	= THIS_MODULE,
443 	.open	= soundcore_open,
444 };
445 
446 static struct sound_unit *__look_for_unit(int chain, int unit)
447 {
448 	struct sound_unit *s;
449 
450 	s=chains[chain];
451 	while(s && s->unit_minor <= unit)
452 	{
453 		if(s->unit_minor==unit)
454 			return s;
455 		s=s->next;
456 	}
457 	return NULL;
458 }
459 
460 int soundcore_open(struct inode *inode, struct file *file)
461 {
462 	int chain;
463 	int unit = iminor(inode);
464 	struct sound_unit *s;
465 	const struct file_operations *new_fops = NULL;
466 
467 	chain=unit&0x0F;
468 	if(chain==4 || chain==5)	/* dsp/audio/dsp16 */
469 	{
470 		unit&=0xF0;
471 		unit|=3;
472 		chain=3;
473 	}
474 
475 	spin_lock(&sound_loader_lock);
476 	s = __look_for_unit(chain, unit);
477 	if (s)
478 		new_fops = fops_get(s->unit_fops);
479 	if (!new_fops) {
480 		spin_unlock(&sound_loader_lock);
481 		/*
482 		 *  Please, don't change this order or code.
483 		 *  For ALSA slot means soundcard and OSS emulation code
484 		 *  comes as add-on modules which aren't depend on
485 		 *  ALSA toplevel modules for soundcards, thus we need
486 		 *  load them at first.	  [Jaroslav Kysela <perex@jcu.cz>]
487 		 */
488 		request_module("sound-slot-%i", unit>>4);
489 		request_module("sound-service-%i-%i", unit>>4, chain);
490 		spin_lock(&sound_loader_lock);
491 		s = __look_for_unit(chain, unit);
492 		if (s)
493 			new_fops = fops_get(s->unit_fops);
494 	}
495 	if (new_fops) {
496 		/*
497 		 * We rely upon the fact that we can't be unloaded while the
498 		 * subdriver is there, so if ->open() is successful we can
499 		 * safely drop the reference counter and if it is not we can
500 		 * revert to old ->f_op. Ugly, indeed, but that's the cost of
501 		 * switching ->f_op in the first place.
502 		 */
503 		int err = 0;
504 		const struct file_operations *old_fops = file->f_op;
505 		file->f_op = new_fops;
506 		spin_unlock(&sound_loader_lock);
507 		if(file->f_op->open)
508 			err = file->f_op->open(inode,file);
509 		if (err) {
510 			fops_put(file->f_op);
511 			file->f_op = fops_get(old_fops);
512 		}
513 		fops_put(old_fops);
514 		return err;
515 	}
516 	spin_unlock(&sound_loader_lock);
517 	return -ENODEV;
518 }
519 
520 MODULE_DESCRIPTION("Core sound module");
521 MODULE_AUTHOR("Alan Cox");
522 MODULE_LICENSE("GPL");
523 MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);
524 
525 static void __exit cleanup_soundcore(void)
526 {
527 	/* We have nothing to really do here - we know the lists must be
528 	   empty */
529 	unregister_chrdev(SOUND_MAJOR, "sound");
530 	class_destroy(sound_class);
531 }
532 
533 static int __init init_soundcore(void)
534 {
535 	if (register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops)==-1) {
536 		printk(KERN_ERR "soundcore: sound device already in use.\n");
537 		return -EBUSY;
538 	}
539 	sound_class = class_create(THIS_MODULE, "sound");
540 	if (IS_ERR(sound_class))
541 		return PTR_ERR(sound_class);
542 
543 	return 0;
544 }
545 
546 module_init(init_soundcore);
547 module_exit(cleanup_soundcore);
548