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
19static int __init init_oss_soundcore(void);
20static void cleanup_oss_soundcore(void);
21#else
22static inline int init_oss_soundcore(void)	{ return 0; }
23static inline void cleanup_oss_soundcore(void)	{ }
24#endif
25
26MODULE_DESCRIPTION("Core sound module");
27MODULE_AUTHOR("Alan Cox");
28MODULE_LICENSE("GPL");
29
30static 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, "snd/%s", dev_name(dev));
35}
36
37const struct class sound_class = {
38	.name = "sound",
39	.devnode = sound_devnode,
40};
41EXPORT_SYMBOL(sound_class);
42
43static 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(&sound_class);
52	if (rc) {
53		cleanup_oss_soundcore();
54		return rc;
55	}
56
57	return 0;
58}
59
60static void __exit cleanup_soundcore(void)
61{
62	cleanup_oss_soundcore();
63	class_unregister(&sound_class);
64}
65
66subsys_initcall(init_soundcore);
67module_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
110struct 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 */
140static int preclaim_oss = IS_ENABLED(CONFIG_SOUND_OSS_CORE_PRECLAIM);
141
142module_param(preclaim_oss, int, 0444);
143
144static int soundcore_open(struct inode *, struct file *);
145
146static 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
159static 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
212static 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
232static 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
239static 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(sizeof(*s), GFP_KERNEL);
242	int r;
243
244	if (!s)
245		return -ENOMEM;
246
247	spin_lock(&sound_loader_lock);
248retry:
249	r = __sound_insert_unit(s, list, fops, index, low, top);
250	spin_unlock(&sound_loader_lock);
251
252	if (r < 0)
253		goto fail;
254	else if (r < SOUND_STEP)
255		sprintf(s->name, "sound/%s", name);
256	else
257		sprintf(s->name, "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, s->unit_minor, 1, s->name,
266				      &soundcore_fops);
267		if (r < 0) {
268			spin_lock(&sound_loader_lock);
269			__sound_remove_unit(list, s->unit_minor);
270			if (index < 0) {
271				low = s->unit_minor + SOUND_STEP;
272				goto retry;
273			}
274			spin_unlock(&sound_loader_lock);
275			r = -EBUSY;
276			goto fail;
277		}
278	}
279
280	device_create(&sound_class, dev, MKDEV(SOUND_MAJOR, s->unit_minor),
281		      NULL, "%s", s->name+6);
282	return s->unit_minor;
283
284fail:
285	kfree(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
295static void sound_remove_unit(struct sound_unit **list, int unit)
296{
297	struct sound_unit *p;
298
299	spin_lock(&sound_loader_lock);
300	p = __sound_remove_unit(list, unit);
301	spin_unlock(&sound_loader_lock);
302	if (p) {
303		if (!preclaim_oss)
304			__unregister_chrdev(SOUND_MAJOR, p->unit_minor, 1,
305					    p->name);
306		device_destroy(&sound_class, MKDEV(SOUND_MAJOR, p->unit_minor));
307		kfree(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
332static 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
347int 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(_name, "unknown%d", chain);
402		    	if (unit >= SOUND_STEP)
403		    		strcat(_name, "-");
404		    	name = _name;
405		}
406		break;
407	}
408	return sound_insert_unit(&chains[chain], fops, -1, unit, max_unit,
409				 name, 0600, dev);
410}
411
412EXPORT_SYMBOL(register_sound_special_device);
413
414int register_sound_special(const struct file_operations *fops, int unit)
415{
416	return register_sound_special_device(fops, unit, NULL);
417}
418
419EXPORT_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
433int register_sound_mixer(const struct file_operations *fops, int dev)
434{
435	return sound_insert_unit(&chains[0], fops, dev, 0, 128,
436				 "mixer", 0600, NULL);
437}
438
439EXPORT_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
461int register_sound_dsp(const struct file_operations *fops, int dev)
462{
463	return sound_insert_unit(&chains[3], fops, dev, 3, 131,
464				 "dsp", 0600, NULL);
465}
466
467EXPORT_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
479void unregister_sound_special(int unit)
480{
481	sound_remove_unit(&chains[unit % SOUND_STEP], unit);
482}
483
484EXPORT_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
494void unregister_sound_mixer(int unit)
495{
496	sound_remove_unit(&chains[0], unit);
497}
498
499EXPORT_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
511void unregister_sound_dsp(int unit)
512{
513	sound_remove_unit(&chains[3], unit);
514}
515
516
517EXPORT_SYMBOL(unregister_sound_dsp);
518
519static 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
533static 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(&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(&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(&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(&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
597MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);
598
599static 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, "sound");
604}
605
606static int __init init_oss_soundcore(void)
607{
608	if (preclaim_oss &&
609	    register_chrdev(SOUND_MAJOR, "sound", &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