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->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. The allocated number is returned on success. On failure
356 * a negative error code is returned.
357 */
358 
359int register_sound_special_device(const struct file_operations *fops, int unit,
360                  struct device *dev)
361{
362    const int chain = unit % SOUND_STEP;
363    int max_unit = 256;
364    const char *name;
365    char _name[16];
366
367    switch (chain) {
368        case 0:
369        name = "mixer";
370        break;
371        case 1:
372        name = "sequencer";
373        if (unit >= SOUND_STEP)
374            goto __unknown;
375        max_unit = unit + 1;
376        break;
377        case 2:
378        name = "midi";
379        break;
380        case 3:
381        name = "dsp";
382        break;
383        case 4:
384        name = "audio";
385        break;
386        case 5:
387        name = "dspW";
388        break;
389        case 8:
390        name = "sequencer2";
391        if (unit >= SOUND_STEP)
392            goto __unknown;
393        max_unit = unit + 1;
394        break;
395        case 9:
396        name = "dmmidi";
397        break;
398        case 10:
399        name = "dmfm";
400        break;
401        case 12:
402        name = "adsp";
403        break;
404        case 13:
405        name = "amidi";
406        break;
407        case 14:
408        name = "admmidi";
409        break;
410        default:
411            {
412            __unknown:
413            sprintf(_name, "unknown%d", chain);
414                if (unit >= SOUND_STEP)
415                    strcat(_name, "-");
416                name = _name;
417        }
418        break;
419    }
420    return sound_insert_unit(&chains[chain], fops, -1, unit, max_unit,
421                 name, S_IRUSR | S_IWUSR, dev);
422}
423 
424EXPORT_SYMBOL(register_sound_special_device);
425
426int register_sound_special(const struct file_operations *fops, int unit)
427{
428    return register_sound_special_device(fops, unit, NULL);
429}
430
431EXPORT_SYMBOL(register_sound_special);
432
433/**
434 * register_sound_mixer - register a mixer device
435 * @fops: File operations for the driver
436 * @dev: Unit number to allocate
437 *
438 * Allocate a mixer device. Unit is the number of the mixer requested.
439 * Pass -1 to request the next free mixer unit. On success the allocated
440 * number is returned, on failure a negative error code is returned.
441 */
442
443int register_sound_mixer(const struct file_operations *fops, int dev)
444{
445    return sound_insert_unit(&chains[0], fops, dev, 0, 128,
446                 "mixer", S_IRUSR | S_IWUSR, NULL);
447}
448
449EXPORT_SYMBOL(register_sound_mixer);
450
451/**
452 * register_sound_midi - register a midi device
453 * @fops: File operations for the driver
454 * @dev: Unit number to allocate
455 *
456 * Allocate a midi device. Unit is the number of the midi device requested.
457 * Pass -1 to request the next free midi unit. On success the allocated
458 * number is returned, on failure a negative error code is returned.
459 */
460
461int register_sound_midi(const struct file_operations *fops, int dev)
462{
463    return sound_insert_unit(&chains[2], fops, dev, 2, 130,
464                 "midi", S_IRUSR | S_IWUSR, NULL);
465}
466
467EXPORT_SYMBOL(register_sound_midi);
468
469/*
470 * DSP's are registered as a triple. Register only one and cheat
471 * in open - see below.
472 */
473 
474/**
475 * register_sound_dsp - register a DSP device
476 * @fops: File operations for the driver
477 * @dev: Unit number to allocate
478 *
479 * Allocate a DSP device. Unit is the number of the DSP requested.
480 * Pass -1 to request the next free DSP unit. On success the allocated
481 * number is returned, on failure a negative error code is returned.
482 *
483 * This function allocates both the audio and dsp device entries together
484 * and will always allocate them as a matching pair - eg dsp3/audio3
485 */
486
487int register_sound_dsp(const struct file_operations *fops, int dev)
488{
489    return sound_insert_unit(&chains[3], fops, dev, 3, 131,
490                 "dsp", S_IWUSR | S_IRUSR, NULL);
491}
492
493EXPORT_SYMBOL(register_sound_dsp);
494
495/**
496 * unregister_sound_special - unregister a special sound device
497 * @unit: unit number to allocate
498 *
499 * Release a sound device that was allocated with
500 * register_sound_special(). The unit passed is the return value from
501 * the register function.
502 */
503
504
505void unregister_sound_special(int unit)
506{
507    sound_remove_unit(&chains[unit % SOUND_STEP], unit);
508}
509 
510EXPORT_SYMBOL(unregister_sound_special);
511
512/**
513 * unregister_sound_mixer - unregister a mixer
514 * @unit: unit number to allocate
515 *
516 * Release a sound device that was allocated with register_sound_mixer().
517 * The unit passed is the return value from the register function.
518 */
519
520void unregister_sound_mixer(int unit)
521{
522    sound_remove_unit(&chains[0], unit);
523}
524
525EXPORT_SYMBOL(unregister_sound_mixer);
526
527/**
528 * unregister_sound_midi - unregister a midi device
529 * @unit: unit number to allocate
530 *
531 * Release a sound device that was allocated with register_sound_midi().
532 * The unit passed is the return value from the register function.
533 */
534
535void unregister_sound_midi(int unit)
536{
537    sound_remove_unit(&chains[2], unit);
538}
539
540EXPORT_SYMBOL(unregister_sound_midi);
541
542/**
543 * unregister_sound_dsp - unregister a DSP device
544 * @unit: unit number to allocate
545 *
546 * Release a sound device that was allocated with register_sound_dsp().
547 * The unit passed is the return value from the register function.
548 *
549 * Both of the allocated units are released together automatically.
550 */
551
552void unregister_sound_dsp(int unit)
553{
554    sound_remove_unit(&chains[3], unit);
555}
556
557
558EXPORT_SYMBOL(unregister_sound_dsp);
559
560static struct sound_unit *__look_for_unit(int chain, int unit)
561{
562    struct sound_unit *s;
563    
564    s=chains[chain];
565    while(s && s->unit_minor <= unit)
566    {
567        if(s->unit_minor==unit)
568            return s;
569        s=s->next;
570    }
571    return NULL;
572}
573
574static int soundcore_open(struct inode *inode, struct file *file)
575{
576    int chain;
577    int unit = iminor(inode);
578    struct sound_unit *s;
579    const struct file_operations *new_fops = NULL;
580
581    chain=unit&0x0F;
582    if(chain==4 || chain==5) /* dsp/audio/dsp16 */
583    {
584        unit&=0xF0;
585        unit|=3;
586        chain=3;
587    }
588    
589    spin_lock(&sound_loader_lock);
590    s = __look_for_unit(chain, unit);
591    if (s)
592        new_fops = fops_get(s->unit_fops);
593    if (preclaim_oss && !new_fops) {
594        spin_unlock(&sound_loader_lock);
595
596        /*
597         * Please, don't change this order or code.
598         * For ALSA slot means soundcard and OSS emulation code
599         * comes as add-on modules which aren't depend on
600         * ALSA toplevel modules for soundcards, thus we need
601         * load them at first. [Jaroslav Kysela <perex@jcu.cz>]
602         */
603        request_module("sound-slot-%i", unit>>4);
604        request_module("sound-service-%i-%i", unit>>4, chain);
605
606        /*
607         * sound-slot/service-* module aliases are scheduled
608         * for removal in favor of the standard char-major-*
609         * module aliases. For the time being, generate both
610         * the legacy and standard module aliases to ease
611         * transition.
612         */
613        if (request_module("char-major-%d-%d", SOUND_MAJOR, unit) > 0)
614            request_module("char-major-%d", SOUND_MAJOR);
615
616        spin_lock(&sound_loader_lock);
617        s = __look_for_unit(chain, unit);
618        if (s)
619            new_fops = fops_get(s->unit_fops);
620    }
621    if (new_fops) {
622        /*
623         * We rely upon the fact that we can't be unloaded while the
624         * subdriver is there, so if ->open() is successful we can
625         * safely drop the reference counter and if it is not we can
626         * revert to old ->f_op. Ugly, indeed, but that's the cost of
627         * switching ->f_op in the first place.
628         */
629        int err = 0;
630        const struct file_operations *old_fops = file->f_op;
631        file->f_op = new_fops;
632        spin_unlock(&sound_loader_lock);
633
634        if (file->f_op->open)
635            err = file->f_op->open(inode,file);
636
637        if (err) {
638            fops_put(file->f_op);
639            file->f_op = fops_get(old_fops);
640        }
641
642        fops_put(old_fops);
643        return err;
644    }
645    spin_unlock(&sound_loader_lock);
646    return -ENODEV;
647}
648
649MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);
650
651static void cleanup_oss_soundcore(void)
652{
653    /* We have nothing to really do here - we know the lists must be
654       empty */
655    unregister_chrdev(SOUND_MAJOR, "sound");
656}
657
658static int __init init_oss_soundcore(void)
659{
660    if (preclaim_oss &&
661        register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) == -1) {
662        printk(KERN_ERR "soundcore: sound device already in use.\n");
663        return -EBUSY;
664    }
665
666    return 0;
667}
668
669#endif /* CONFIG_SOUND_OSS_CORE */
670

Archive Download this file



interactive