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/types.h>
108#include <linux/kernel.h>
109#include <linux/sound.h>
110#include <linux/kmod.h>
111
112#define SOUND_STEP 16
113
114struct 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#ifdef CONFIG_SOUND_MSNDCLAS
123extern int msnd_classic_init(void);
124#endif
125#ifdef CONFIG_SOUND_MSNDPIN
126extern int msnd_pinnacle_init(void);
127#endif
128
129/*
130 * By default, OSS sound_core claims full legacy minor range (0-255)
131 * of SOUND_MAJOR to trap open attempts to any sound minor and
132 * requests modules using custom sound-slot/service-* module aliases.
133 * The only benefit of doing this is allowing use of custom module
134 * aliases instead of the standard char-major-* ones. This behavior
135 * prevents alternative OSS implementation and is scheduled to be
136 * removed.
137 *
138 * CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss kernel
139 * parameter are added to allow distros and developers to try and
140 * switch to alternative implementations without needing to rebuild
141 * the kernel in the meantime. If preclaim_oss is non-zero, the
142 * kernel will behave the same as before. All SOUND_MAJOR minors are
143 * preclaimed and the custom module aliases along with standard chrdev
144 * ones are emitted if a missing device is opened. If preclaim_oss is
145 * zero, sound_core only grabs what's actually in use and for missing
146 * devices only the standard chrdev aliases are requested.
147 *
148 * All these clutters are scheduled to be removed along with
149 * sound-slot/service-* module aliases. Please take a look at
150 * feature-removal-schedule.txt for details.
151 */
152#ifdef CONFIG_SOUND_OSS_CORE_PRECLAIM
153static int preclaim_oss = 1;
154#else
155static int preclaim_oss = 0;
156#endif
157
158module_param(preclaim_oss, int, 0444);
159
160static int soundcore_open(struct inode *, struct file *);
161
162static const struct file_operations soundcore_fops =
163{
164    /* We must have an owner or the module locking fails */
165    .owner = THIS_MODULE,
166    .open = soundcore_open,
167    .llseek = noop_llseek,
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 5:
388        name = "dspW";
389        break;
390        case 8:
391        name = "sequencer2";
392        if (unit >= SOUND_STEP)
393            goto __unknown;
394        max_unit = unit + 1;
395        break;
396        case 9:
397        name = "dmmidi";
398        break;
399        case 10:
400        name = "dmfm";
401        break;
402        case 12:
403        name = "adsp";
404        break;
405        case 13:
406        name = "amidi";
407        break;
408        case 14:
409        name = "admmidi";
410        break;
411        default:
412            {
413            __unknown:
414            sprintf(_name, "unknown%d", chain);
415                if (unit >= SOUND_STEP)
416                    strcat(_name, "-");
417                name = _name;
418        }
419        break;
420    }
421    return sound_insert_unit(&chains[chain], fops, -1, unit, max_unit,
422                 name, S_IRUSR | S_IWUSR, dev);
423}
424 
425EXPORT_SYMBOL(register_sound_special_device);
426
427int register_sound_special(const struct file_operations *fops, int unit)
428{
429    return register_sound_special_device(fops, unit, NULL);
430}
431
432EXPORT_SYMBOL(register_sound_special);
433
434/**
435 * register_sound_mixer - register a mixer device
436 * @fops: File operations for the driver
437 * @dev: Unit number to allocate
438 *
439 * Allocate a mixer device. Unit is the number of the mixer requested.
440 * Pass -1 to request the next free mixer unit. On success the allocated
441 * number is returned, on failure a negative error code is returned.
442 */
443
444int register_sound_mixer(const struct file_operations *fops, int dev)
445{
446    return sound_insert_unit(&chains[0], fops, dev, 0, 128,
447                 "mixer", S_IRUSR | S_IWUSR, NULL);
448}
449
450EXPORT_SYMBOL(register_sound_mixer);
451
452/**
453 * register_sound_midi - register a midi device
454 * @fops: File operations for the driver
455 * @dev: Unit number to allocate
456 *
457 * Allocate a midi device. Unit is the number of the midi device requested.
458 * Pass -1 to request the next free midi unit. On success the allocated
459 * number is returned, on failure a negative error code is returned.
460 */
461
462int register_sound_midi(const struct file_operations *fops, int dev)
463{
464    return sound_insert_unit(&chains[2], fops, dev, 2, 130,
465                 "midi", S_IRUSR | S_IWUSR, NULL);
466}
467
468EXPORT_SYMBOL(register_sound_midi);
469
470/*
471 * DSP's are registered as a triple. Register only one and cheat
472 * in open - see below.
473 */
474 
475/**
476 * register_sound_dsp - register a DSP device
477 * @fops: File operations for the driver
478 * @dev: Unit number to allocate
479 *
480 * Allocate a DSP device. Unit is the number of the DSP requested.
481 * Pass -1 to request the next free DSP unit. On success the allocated
482 * number is returned, on failure a negative error code is returned.
483 *
484 * This function allocates both the audio and dsp device entries together
485 * and will always allocate them as a matching pair - eg dsp3/audio3
486 */
487
488int register_sound_dsp(const struct file_operations *fops, int dev)
489{
490    return sound_insert_unit(&chains[3], fops, dev, 3, 131,
491                 "dsp", S_IWUSR | S_IRUSR, NULL);
492}
493
494EXPORT_SYMBOL(register_sound_dsp);
495
496/**
497 * unregister_sound_special - unregister a special sound device
498 * @unit: unit number to allocate
499 *
500 * Release a sound device that was allocated with
501 * register_sound_special(). The unit passed is the return value from
502 * the register function.
503 */
504
505
506void unregister_sound_special(int unit)
507{
508    sound_remove_unit(&chains[unit % SOUND_STEP], unit);
509}
510 
511EXPORT_SYMBOL(unregister_sound_special);
512
513/**
514 * unregister_sound_mixer - unregister a mixer
515 * @unit: unit number to allocate
516 *
517 * Release a sound device that was allocated with register_sound_mixer().
518 * The unit passed is the return value from the register function.
519 */
520
521void unregister_sound_mixer(int unit)
522{
523    sound_remove_unit(&chains[0], unit);
524}
525
526EXPORT_SYMBOL(unregister_sound_mixer);
527
528/**
529 * unregister_sound_midi - unregister a midi device
530 * @unit: unit number to allocate
531 *
532 * Release a sound device that was allocated with register_sound_midi().
533 * The unit passed is the return value from the register function.
534 */
535
536void unregister_sound_midi(int unit)
537{
538    sound_remove_unit(&chains[2], unit);
539}
540
541EXPORT_SYMBOL(unregister_sound_midi);
542
543/**
544 * unregister_sound_dsp - unregister a DSP device
545 * @unit: unit number to allocate
546 *
547 * Release a sound device that was allocated with register_sound_dsp().
548 * The unit passed is the return value from the register function.
549 *
550 * Both of the allocated units are released together automatically.
551 */
552
553void unregister_sound_dsp(int unit)
554{
555    sound_remove_unit(&chains[3], unit);
556}
557
558
559EXPORT_SYMBOL(unregister_sound_dsp);
560
561static struct sound_unit *__look_for_unit(int chain, int unit)
562{
563    struct sound_unit *s;
564    
565    s=chains[chain];
566    while(s && s->unit_minor <= unit)
567    {
568        if(s->unit_minor==unit)
569            return s;
570        s=s->next;
571    }
572    return NULL;
573}
574
575static int soundcore_open(struct inode *inode, struct file *file)
576{
577    int chain;
578    int unit = iminor(inode);
579    struct sound_unit *s;
580    const struct file_operations *new_fops = NULL;
581
582    chain=unit&0x0F;
583    if(chain==4 || chain==5) /* dsp/audio/dsp16 */
584    {
585        unit&=0xF0;
586        unit|=3;
587        chain=3;
588    }
589    
590    spin_lock(&sound_loader_lock);
591    s = __look_for_unit(chain, unit);
592    if (s)
593        new_fops = fops_get(s->unit_fops);
594    if (preclaim_oss && !new_fops) {
595        spin_unlock(&sound_loader_lock);
596
597        /*
598         * Please, don't change this order or code.
599         * For ALSA slot means soundcard and OSS emulation code
600         * comes as add-on modules which aren't depend on
601         * ALSA toplevel modules for soundcards, thus we need
602         * load them at first. [Jaroslav Kysela <perex@jcu.cz>]
603         */
604        request_module("sound-slot-%i", unit>>4);
605        request_module("sound-service-%i-%i", unit>>4, chain);
606
607        /*
608         * sound-slot/service-* module aliases are scheduled
609         * for removal in favor of the standard char-major-*
610         * module aliases. For the time being, generate both
611         * the legacy and standard module aliases to ease
612         * transition.
613         */
614        if (request_module("char-major-%d-%d", SOUND_MAJOR, unit) > 0)
615            request_module("char-major-%d", SOUND_MAJOR);
616
617        spin_lock(&sound_loader_lock);
618        s = __look_for_unit(chain, unit);
619        if (s)
620            new_fops = fops_get(s->unit_fops);
621    }
622    if (new_fops) {
623        /*
624         * We rely upon the fact that we can't be unloaded while the
625         * subdriver is there, so if ->open() is successful we can
626         * safely drop the reference counter and if it is not we can
627         * revert to old ->f_op. Ugly, indeed, but that's the cost of
628         * switching ->f_op in the first place.
629         */
630        int err = 0;
631        const struct file_operations *old_fops = file->f_op;
632        file->f_op = new_fops;
633        spin_unlock(&sound_loader_lock);
634
635        if (file->f_op->open)
636            err = file->f_op->open(inode,file);
637
638        if (err) {
639            fops_put(file->f_op);
640            file->f_op = fops_get(old_fops);
641        }
642
643        fops_put(old_fops);
644        return err;
645    }
646    spin_unlock(&sound_loader_lock);
647    return -ENODEV;
648}
649
650MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);
651
652static void cleanup_oss_soundcore(void)
653{
654    /* We have nothing to really do here - we know the lists must be
655       empty */
656    unregister_chrdev(SOUND_MAJOR, "sound");
657}
658
659static int __init init_oss_soundcore(void)
660{
661    if (preclaim_oss &&
662        register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) == -1) {
663        printk(KERN_ERR "soundcore: sound device already in use.\n");
664        return -EBUSY;
665    }
666
667    return 0;
668}
669
670#endif /* CONFIG_SOUND_OSS_CORE */
671

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