sound/sound_core.c

   1 /*
   2  *      Sound core handling. Breaks out sound functions to submodules
   3  *
   4  *      Author:         Alan Cox <alan.cox@linux.org>
   5  *
   6  *      Fixes:
   7  *
   8  *
   9  *      This program is free software; you can redistribute it and/or
  10  *      modify it under the terms of the GNU General Public License
  11  *      as published by the Free Software Foundation; either version
  12  *      2 of the License, or (at your option) any later version.
  13  *
  14  *                         --------------------
  15  *
  16  *      Top level handler for the sound subsystem. Various devices can
  17  *      plug into this. The fact they don't all go via OSS doesn't mean
  18  *      they don't have to implement the OSS API. There is a lot of logic
  19  *      to keeping much of the OSS weight out of the code in a compatibility
  20  *      module, but it's up to the driver to rember to load it...
  21  *
  22  *      The code provides a set of functions for registration of devices
  23  *      by type. This is done rather than providing a single call so that
  24  *      we can hide any future changes in the internals (eg when we go to
  25  *      32bit dev_t) from the modules and their interface.
  26  *
  27  *      Secondly we need to allocate the dsp, dsp16 and audio devices as
  28  *      one. Thus we misuse the chains a bit to simplify this.
  29  *
  30  *      Thirdly to make it more fun and for 2.3.x and above we do all
  31  *      of this using fine grained locking.
  32  *
  33  *      FIXME: we have to resolve modules and fine grained load/unload
  34  *      locking at some point in 2.3.x.
  35  */
  36
  37 #include <linux/module.h>
  38 #include <linux/init.h>
  39 #include <linux/slab.h>
  40 #include <linux/smp_lock.h>
  41 #include <linux/types.h>
  42 #include <linux/kernel.h>
  43 #include <linux/fs.h>
  44 #include <linux/sound.h>
  45 #include <linux/major.h>
  46 #include <linux/kmod.h>
  47 #include <linux/device.h>
  48
  49 #define SOUND_STEP 16
  50
  51
  52 struct sound_unit
  53 {
  54         int unit_minor;
  55         const struct file_operations *unit_fops;
  56         struct sound_unit *next;
  57         char name[32];
  58 };
  59
  60 #ifdef CONFIG_SOUND_MSNDCLAS
  61 extern int msnd_classic_init(void);
  62 #endif
  63 #ifdef CONFIG_SOUND_MSNDPIN
  64 extern int msnd_pinnacle_init(void);
  65 #endif
  66
  67 struct class *sound_class;
  68 EXPORT_SYMBOL(sound_class);
  69
  70 /*
  71  *      Low level list operator. Scan the ordered list, find a hole and
  72  *      join into it. Called with the lock asserted
  73  */
  74
  75 static int __sound_insert_unit(struct sound_unit * s, struct sound_unit **list, const struct file_operations *fops, int index, int low, int top)
  76 {
  77         int n=low;
  78
  79         if (index < 0) {        /* first free */
  80
  81                 while (*list && (*list)->unit_minor<n)
  82                         list=&((*list)->next);
  83
  84                 while(n<top)
  85                 {
  86                         /* Found a hole ? */
  87                         if(*list==NULL || (*list)->unit_minor>n)
  88                                 break;
  89                         list=&((*list)->next);
  90                         n+=SOUND_STEP;
  91                 }
  92
  93                 if(n>=top)
  94                         return -ENOENT;
  95         } else {
  96                 n = low+(index*16);
  97                 while (*list) {
  98                         if ((*list)->unit_minor==n)
  99                                 return -EBUSY;
 100                         if ((*list)->unit_minor>n)
 101                                 break;
 102                         list=&((*list)->next);
 103                 }
 104         }
 105
 106         /*
 107          *      Fill it in
 108          */
 109
 110         s->unit_minor=n;
 111         s->unit_fops=fops;
 112
 113         /*
 114          *      Link it
 115          */
 116
 117         s->next=*list;
 118         *list=s;
 119
 120
 121         return n;
 122 }
 123
 124 /*
 125  *      Remove a node from the chain. Called with the lock asserted
 126  */
 127
 128 static struct sound_unit *__sound_remove_unit(struct sound_unit **list, int unit)
 129 {
 130         while(*list)
 131         {
 132                 struct sound_unit *p=*list;
 133                 if(p->unit_minor==unit)
 134                 {
 135                         *list=p->next;
 136                         return p;
 137                 }
 138                 list=&(p->next);
 139         }
 140         printk(KERN_ERR "Sound device %d went missing!\n", unit);
 141         return NULL;
 142 }
 143
 144 /*
 145  *      This lock guards the sound loader list.
 146  */
 147
 148 static DEFINE_SPINLOCK(sound_loader_lock);
 149
 150 /*
 151  *      Allocate the controlling structure and add it to the sound driver
 152  *      list. Acquires locks as needed
 153  */
 154
 155 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)
 156 {
 157         struct sound_unit *s = kmalloc(sizeof(*s), GFP_KERNEL);
 158         int r;
 159
 160         if (!s)
 161                 return -ENOMEM;
 162
 163         spin_lock(&sound_loader_lock);
 164         r = __sound_insert_unit(s, list, fops, index, low, top);
 165         spin_unlock(&sound_loader_lock);
 166
 167         if (r < 0)
 168                 goto fail;
 169         else if (r < SOUND_STEP)
 170                 sprintf(s->name, "sound/%s", name);
 171         else
 172                 sprintf(s->name, "sound/%s%d", name, r / SOUND_STEP);
 173
 174         device_create_drvdata(sound_class, dev,
 175                               MKDEV(SOUND_MAJOR, s->unit_minor),
 176                               NULL, s->name+6);
 177         return r;
 178
 179  fail:
 180         kfree(s);
 181         return r;
 182 }
 183
 184 /*
 185  *      Remove a unit. Acquires locks as needed. The drivers MUST have
 186  *      completed the removal before their file operations become
 187  *      invalid.
 188  */
 189
 190 static void sound_remove_unit(struct sound_unit **list, int unit)
 191 {
 192         struct sound_unit *p;
 193
 194         spin_lock(&sound_loader_lock);
 195         p = __sound_remove_unit(list, unit);
 196         spin_unlock(&sound_loader_lock);
 197         if (p) {
 198                 device_destroy(sound_class, MKDEV(SOUND_MAJOR, p->unit_minor));
 199                 kfree(p);
 200         }
 201 }
 202
 203 /*
 204  *      Allocations
 205  *
 206  *      0       *16             Mixers
 207  *      1       *8              Sequencers
 208  *      2       *16             Midi
 209  *      3       *16             DSP
 210  *      4       *16             SunDSP
 211  *      5       *16             DSP16
 212  *      6       --              sndstat (obsolete)
 213  *      7       *16             unused
 214  *      8       --              alternate sequencer (see above)
 215  *      9       *16             raw synthesizer access
 216  *      10      *16             unused
 217  *      11      *16             unused
 218  *      12      *16             unused
 219  *      13      *16             unused
 220  *      14      *16             unused
 221  *      15      *16             unused
 222  */
 223
 224 static struct sound_unit *chains[SOUND_STEP];
 225
 226 /**
 227  *      register_sound_special_device - register a special sound node
 228  *      @fops: File operations for the driver
 229  *      @unit: Unit number to allocate
 230  *      @dev: device pointer
 231  *
 232  *      Allocate a special sound device by minor number from the sound
 233  *      subsystem. The allocated number is returned on succes. On failure
 234  *      a negative error code is returned.
 235  */
 236
 237 int register_sound_special_device(const struct file_operations *fops, int unit,
 238                                   struct device *dev)
 239 {
 240         const int chain = unit % SOUND_STEP;
 241         int max_unit = 128 + chain;
 242         const char *name;
 243         char _name[16];
 244
 245         switch (chain) {
 246             case 0:
 247                 name = "mixer";
 248                 break;
 249             case 1:
 250                 name = "sequencer";
 251                 if (unit >= SOUND_STEP)
 252                         goto __unknown;
 253                 max_unit = unit + 1;
 254                 break;
 255             case 2:
 256                 name = "midi";
 257                 break;
 258             case 3:
 259                 name = "dsp";
 260                 break;
 261             case 4:
 262                 name = "audio";
 263                 break;
 264             case 8:
 265                 name = "sequencer2";
 266                 if (unit >= SOUND_STEP)
 267                         goto __unknown;
 268                 max_unit = unit + 1;
 269                 break;
 270             case 9:
 271                 name = "dmmidi";
 272                 break;
 273             case 10:
 274                 name = "dmfm";
 275                 break;
 276             case 12:
 277                 name = "adsp";
 278                 break;
 279             case 13:
 280                 name = "amidi";
 281                 break;
 282             case 14:
 283                 name = "admmidi";
 284                 break;
 285             default:
 286                 {
 287                     __unknown:
 288                         sprintf(_name, "unknown%d", chain);
 289                         if (unit >= SOUND_STEP)
 290                                 strcat(_name, "-");
 291                         name = _name;
 292                 }
 293                 break;
 294         }
 295         return sound_insert_unit(&chains[chain], fops, -1, unit, max_unit,
 296                                  name, S_IRUSR | S_IWUSR, dev);
 297 }
 298
 299 EXPORT_SYMBOL(register_sound_special_device);
 300
 301 int register_sound_special(const struct file_operations *fops, int unit)
 302 {
 303         return register_sound_special_device(fops, unit, NULL);
 304 }
 305
 306 EXPORT_SYMBOL(register_sound_special);
 307
 308 /**
 309  *      register_sound_mixer - register a mixer device
 310  *      @fops: File operations for the driver
 311  *      @dev: Unit number to allocate
 312  *
 313  *      Allocate a mixer device. Unit is the number of the mixer requested.
 314  *      Pass -1 to request the next free mixer unit. On success the allocated
 315  *      number is returned, on failure a negative error code is returned.
 316  */
 317
 318 int register_sound_mixer(const struct file_operations *fops, int dev)
 319 {
 320         return sound_insert_unit(&chains[0], fops, dev, 0, 128,
 321                                  "mixer", S_IRUSR | S_IWUSR, NULL);
 322 }
 323
 324 EXPORT_SYMBOL(register_sound_mixer);
 325
 326 /**
 327  *      register_sound_midi - register a midi device
 328  *      @fops: File operations for the driver
 329  *      @dev: Unit number to allocate
 330  *
 331  *      Allocate a midi device. Unit is the number of the midi device requested.
 332  *      Pass -1 to request the next free midi unit. On success the allocated
 333  *      number is returned, on failure a negative error code is returned.
 334  */
 335
 336 int register_sound_midi(const struct file_operations *fops, int dev)
 337 {
 338         return sound_insert_unit(&chains[2], fops, dev, 2, 130,
 339                                  "midi", S_IRUSR | S_IWUSR, NULL);
 340 }
 341
 342 EXPORT_SYMBOL(register_sound_midi);
 343
 344 /*
 345  *      DSP's are registered as a triple. Register only one and cheat
 346  *      in open - see below.
 347  */
 348
 349 /**
 350  *      register_sound_dsp - register a DSP device
 351  *      @fops: File operations for the driver
 352  *      @dev: Unit number to allocate
 353  *
 354  *      Allocate a DSP device. Unit is the number of the DSP requested.
 355  *      Pass -1 to request the next free DSP unit. On success the allocated
 356  *      number is returned, on failure a negative error code is returned.
 357  *
 358  *      This function allocates both the audio and dsp device entries together
 359  *      and will always allocate them as a matching pair - eg dsp3/audio3
 360  */
 361
 362 int register_sound_dsp(const struct file_operations *fops, int dev)
 363 {
 364         return sound_insert_unit(&chains[3], fops, dev, 3, 131,
 365                                  "dsp", S_IWUSR | S_IRUSR, NULL);
 366 }
 367
 368 EXPORT_SYMBOL(register_sound_dsp);
 369
 370 /**
 371  *      unregister_sound_special - unregister a special sound device
 372  *      @unit: unit number to allocate
 373  *
 374  *      Release a sound device that was allocated with
 375  *      register_sound_special(). The unit passed is the return value from
 376  *      the register function.
 377  */
 378
 379
 380 void unregister_sound_special(int unit)
 381 {
 382         sound_remove_unit(&chains[unit % SOUND_STEP], unit);
 383 }
 384
 385 EXPORT_SYMBOL(unregister_sound_special);
 386
 387 /**
 388  *      unregister_sound_mixer - unregister a mixer
 389  *      @unit: unit number to allocate
 390  *
 391  *      Release a sound device that was allocated with register_sound_mixer().
 392  *      The unit passed is the return value from the register function.
 393  */
 394
 395 void unregister_sound_mixer(int unit)
 396 {
 397         sound_remove_unit(&chains[0], unit);
 398 }
 399
 400 EXPORT_SYMBOL(unregister_sound_mixer);
 401
 402 /**
 403  *      unregister_sound_midi - unregister a midi device
 404  *      @unit: unit number to allocate
 405  *
 406  *      Release a sound device that was allocated with register_sound_midi().
 407  *      The unit passed is the return value from the register function.
 408  */
 409
 410 void unregister_sound_midi(int unit)
 411 {
 412         return sound_remove_unit(&chains[2], unit);
 413 }
 414
 415 EXPORT_SYMBOL(unregister_sound_midi);
 416
 417 /**
 418  *      unregister_sound_dsp - unregister a DSP device
 419  *      @unit: unit number to allocate
 420  *
 421  *      Release a sound device that was allocated with register_sound_dsp().
 422  *      The unit passed is the return value from the register function.
 423  *
 424  *      Both of the allocated units are released together automatically.
 425  */
 426
 427 void unregister_sound_dsp(int unit)
 428 {
 429         return sound_remove_unit(&chains[3], unit);
 430 }
 431
 432
 433 EXPORT_SYMBOL(unregister_sound_dsp);
 434
 435 /*
 436  *      Now our file operations
 437  */
 438
 439 static int soundcore_open(struct inode *, struct file *);
 440
 441 static const struct file_operations soundcore_fops=
 442 {
 443         /* We must have an owner or the module locking fails */
 444         .owner  = THIS_MODULE,
 445         .open   = soundcore_open,
 446 };
 447
 448 static struct sound_unit *__look_for_unit(int chain, int unit)
 449 {
 450         struct sound_unit *s;
 451
 452         s=chains[chain];
 453         while(s && s->unit_minor <= unit)
 454         {
 455                 if(s->unit_minor==unit)
 456                         return s;
 457                 s=s->next;
 458         }
 459         return NULL;
 460 }
 461
 462 int soundcore_open(struct inode *inode, struct file *file)
 463 {
 464         int chain;
 465         int unit = iminor(inode);
 466         struct sound_unit *s;
 467         const struct file_operations *new_fops = NULL;
 468
 469         lock_kernel ();
 470
 471         chain=unit&0x0F;
 472         if(chain==4 || chain==5)        /* dsp/audio/dsp16 */
 473         {
 474                 unit&=0xF0;
 475                 unit|=3;
 476                 chain=3;
 477         }
 478
 479         spin_lock(&sound_loader_lock);
 480         s = __look_for_unit(chain, unit);
 481         if (s)
 482                 new_fops = fops_get(s->unit_fops);
 483         if (!new_fops) {
 484                 spin_unlock(&sound_loader_lock);
 485                 /*
 486                  *  Please, don't change this order or code.
 487                  *  For ALSA slot means soundcard and OSS emulation code
 488                  *  comes as add-on modules which aren't depend on
 489                  *  ALSA toplevel modules for soundcards, thus we need
 490                  *  load them at first.   [Jaroslav Kysela <perex@jcu.cz>]
 491                  */
 492                 request_module("sound-slot-%i", unit>>4);
 493                 request_module("sound-service-%i-%i", unit>>4, chain);
 494                 spin_lock(&sound_loader_lock);
 495                 s = __look_for_unit(chain, unit);
 496                 if (s)
 497                         new_fops = fops_get(s->unit_fops);
 498         }
 499         if (new_fops) {
 500                 /*
 501                  * We rely upon the fact that we can't be unloaded while the
 502                  * subdriver is there, so if ->open() is successful we can
 503                  * safely drop the reference counter and if it is not we can
 504                  * revert to old ->f_op. Ugly, indeed, but that's the cost of
 505                  * switching ->f_op in the first place.
 506                  */
 507                 int err = 0;
 508                 const struct file_operations *old_fops = file->f_op;
 509                 file->f_op = new_fops;
 510                 spin_unlock(&sound_loader_lock);
 511                 if(file->f_op->open)
 512                         err = file->f_op->open(inode,file);
 513                 if (err) {
 514                         fops_put(file->f_op);
 515                         file->f_op = fops_get(old_fops);
 516                 }
 517                 fops_put(old_fops);
 518                 unlock_kernel();
 519                 return err;
 520         }
 521         spin_unlock(&sound_loader_lock);
 522         unlock_kernel();
 523         return -ENODEV;
 524 }
 525
 526 MODULE_DESCRIPTION("Core sound module");
 527 MODULE_AUTHOR("Alan Cox");
 528 MODULE_LICENSE("GPL");
 529 MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);
 530
 531 static void __exit cleanup_soundcore(void)
 532 {
 533         /* We have nothing to really do here - we know the lists must be
 534            empty */
 535         unregister_chrdev(SOUND_MAJOR, "sound");
 536         class_destroy(sound_class);
 537 }
 538
 539 static int __init init_soundcore(void)
 540 {
 541         if (register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops)==-1) {
 542                 printk(KERN_ERR "soundcore: sound device already in use.\n");
 543                 return -EBUSY;
 544         }
 545         sound_class = class_create(THIS_MODULE, "sound");
 546         if (IS_ERR(sound_class))
 547                 return PTR_ERR(sound_class);
 548
 549         return 0;
 550 }
 551
 552 module_init(init_soundcore);
 553 module_exit(cleanup_soundcore);