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

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