Root/sound/sound_core.c

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
18static int __init init_oss_soundcore(void);
19static void cleanup_oss_soundcore(void);
20#else
21static inline int init_oss_soundcore(void) { return 0; }
22static inline void cleanup_oss_soundcore(void) { }
23#endif
24
25struct class *sound_class;
26EXPORT_SYMBOL(sound_class);
27
28MODULE_DESCRIPTION("Core sound module");
29MODULE_AUTHOR("Alan Cox");
30MODULE_LICENSE("GPL");
31
32static 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
39static 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
58static void __exit cleanup_soundcore(void)
59{
60    cleanup_oss_soundcore();
61    class_destroy(sound_class);
62}
63
64subsys_initcall(init_soundcore);
65module_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
115struct 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
124extern int msnd_classic_init(void);
125#endif
126#ifdef CONFIG_SOUND_MSNDPIN
127extern 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
154static int preclaim_oss = 1;
155#else
156static int preclaim_oss = 0;
157#endif
158
159module_param(preclaim_oss, int, 0444);
160
161static int soundcore_open(struct inode *, struct file *);
162
163static 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
175static 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 
228static 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
248static 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
255static 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);
264retry:
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
299fail:
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     
310static 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
347static 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 
360int 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 
422EXPORT_SYMBOL(register_sound_special_device);
423
424int register_sound_special(const struct file_operations *fops, int unit)
425{
426    return register_sound_special_device(fops, unit, NULL);
427}
428
429EXPORT_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
441int 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
447EXPORT_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
459int 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
465EXPORT_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
485int 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
491EXPORT_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
503void unregister_sound_special(int unit)
504{
505    sound_remove_unit(&chains[unit % SOUND_STEP], unit);
506}
507 
508EXPORT_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
518void unregister_sound_mixer(int unit)
519{
520    sound_remove_unit(&chains[0], unit);
521}
522
523EXPORT_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
533void unregister_sound_midi(int unit)
534{
535    sound_remove_unit(&chains[2], unit);
536}
537
538EXPORT_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
550void unregister_sound_dsp(int unit)
551{
552    sound_remove_unit(&chains[3], unit);
553}
554
555
556EXPORT_SYMBOL(unregister_sound_dsp);
557
558static 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
572static 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    chain=unit&0x0F;
580    if(chain==4 || chain==5) /* dsp/audio/dsp16 */
581    {
582        unit&=0xF0;
583        unit|=3;
584        chain=3;
585    }
586    
587    spin_lock(&sound_loader_lock);
588    s = __look_for_unit(chain, unit);
589    if (s)
590        new_fops = fops_get(s->unit_fops);
591    if (preclaim_oss && !new_fops) {
592        spin_unlock(&sound_loader_lock);
593
594        /*
595         * Please, don't change this order or code.
596         * For ALSA slot means soundcard and OSS emulation code
597         * comes as add-on modules which aren't depend on
598         * ALSA toplevel modules for soundcards, thus we need
599         * load them at first. [Jaroslav Kysela <perex@jcu.cz>]
600         */
601        request_module("sound-slot-%i", unit>>4);
602        request_module("sound-service-%i-%i", unit>>4, chain);
603
604        /*
605         * sound-slot/service-* module aliases are scheduled
606         * for removal in favor of the standard char-major-*
607         * module aliases. For the time being, generate both
608         * the legacy and standard module aliases to ease
609         * transition.
610         */
611        if (request_module("char-major-%d-%d", SOUND_MAJOR, unit) > 0)
612            request_module("char-major-%d", SOUND_MAJOR);
613
614        spin_lock(&sound_loader_lock);
615        s = __look_for_unit(chain, unit);
616        if (s)
617            new_fops = fops_get(s->unit_fops);
618    }
619    if (new_fops) {
620        /*
621         * We rely upon the fact that we can't be unloaded while the
622         * subdriver is there, so if ->open() is successful we can
623         * safely drop the reference counter and if it is not we can
624         * revert to old ->f_op. Ugly, indeed, but that's the cost of
625         * switching ->f_op in the first place.
626         */
627        int err = 0;
628        const struct file_operations *old_fops = file->f_op;
629        file->f_op = new_fops;
630        spin_unlock(&sound_loader_lock);
631
632        if (file->f_op->open)
633            err = file->f_op->open(inode,file);
634
635        if (err) {
636            fops_put(file->f_op);
637            file->f_op = fops_get(old_fops);
638        }
639
640        fops_put(old_fops);
641        return err;
642    }
643    spin_unlock(&sound_loader_lock);
644    return -ENODEV;
645}
646
647MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);
648
649static void cleanup_oss_soundcore(void)
650{
651    /* We have nothing to really do here - we know the lists must be
652       empty */
653    unregister_chrdev(SOUND_MAJOR, "sound");
654}
655
656static int __init init_oss_soundcore(void)
657{
658    if (preclaim_oss &&
659        register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) == -1) {
660        printk(KERN_ERR "soundcore: sound device already in use.\n");
661        return -EBUSY;
662    }
663
664    return 0;
665}
666
667#endif /* CONFIG_SOUND_OSS_CORE */
668

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