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Linux/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
 18 static int __init init_oss_soundcore(void);
 19 static void cleanup_oss_soundcore(void);
 20 #else
 21 static inline int init_oss_soundcore(void)      { return 0; }
 22 static inline void cleanup_oss_soundcore(void)  { }
 23 #endif
 24 
 25 struct class *sound_class;
 26 EXPORT_SYMBOL(sound_class);
 27 
 28 MODULE_DESCRIPTION("Core sound module");
 29 MODULE_AUTHOR("Alan Cox");
 30 MODULE_LICENSE("GPL");
 31 
 32 static 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 
 39 static 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 
 58 static void __exit cleanup_soundcore(void)
 59 {
 60         cleanup_oss_soundcore();
 61         class_destroy(sound_class);
 62 }
 63 
 64 subsys_initcall(init_soundcore);
 65 module_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 
114 struct 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
123 extern int msnd_classic_init(void);
124 #endif
125 #ifdef CONFIG_SOUND_MSNDPIN
126 extern 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
152 static int preclaim_oss = 1;
153 #else
154 static int preclaim_oss = 0;
155 #endif
156 
157 module_param(preclaim_oss, int, 0444);
158 
159 static int soundcore_open(struct inode *, struct file *);
160 
161 static 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 
174 static 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  
227 static 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 
247 static 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 
254 static 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);
263 retry:
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 
298 fail:
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         
309 static 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 
346 static 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  
361 int 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  
426 EXPORT_SYMBOL(register_sound_special_device);
427 
428 int register_sound_special(const struct file_operations *fops, int unit)
429 {
430         return register_sound_special_device(fops, unit, NULL);
431 }
432 
433 EXPORT_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 
447 int 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 
453 EXPORT_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 
467 int 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 
473 EXPORT_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 
495 int 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 
501 EXPORT_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 
513 void unregister_sound_special(int unit)
514 {
515         sound_remove_unit(&chains[unit % SOUND_STEP], unit);
516 }
517  
518 EXPORT_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 
528 void unregister_sound_mixer(int unit)
529 {
530         sound_remove_unit(&chains[0], unit);
531 }
532 
533 EXPORT_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 
543 void unregister_sound_midi(int unit)
544 {
545         sound_remove_unit(&chains[2], unit);
546 }
547 
548 EXPORT_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 
560 void unregister_sound_dsp(int unit)
561 {
562         sound_remove_unit(&chains[3], unit);
563 }
564 
565 
566 EXPORT_SYMBOL(unregister_sound_dsp);
567 
568 static 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 
582 static 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 
646 MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);
647 
648 static 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 
655 static int __init init_oss_soundcore(void)
656 {
657         if (preclaim_oss &&
658             register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) < 0) {
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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