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(sound_class, dev, MKDEV(SOUND_MAJOR, s->unit_minor),
 175                       s->name+6);
 176         return r;
 177
 178  fail:
 179         kfree(s);
 180         return r;
 181 }
 182
 183 /*
 184  *      Remove a unit. Acquires locks as needed. The drivers MUST have
 185  *      completed the removal before their file operations become
 186  *      invalid.
 187  */
 188
 189 static void sound_remove_unit(struct sound_unit **list, int unit)
 190 {
 191         struct sound_unit *p;
 192
 193         spin_lock(&sound_loader_lock);
 194         p = __sound_remove_unit(list, unit);
 195         spin_unlock(&sound_loader_lock);
 196         if (p) {
 197                 device_destroy(sound_class, MKDEV(SOUND_MAJOR, p->unit_minor));
 198                 kfree(p);
 199         }
 200 }
 201
 202 /*
 203  *      Allocations
 204  *
 205  *      0       *16             Mixers
 206  *      1       *8              Sequencers
 207  *      2       *16             Midi
 208  *      3       *16             DSP
 209  *      4       *16             SunDSP
 210  *      5       *16             DSP16
 211  *      6       --              sndstat (obsolete)
 212  *      7       *16             unused
 213  *      8       --              alternate sequencer (see above)
 214  *      9       *16             raw synthesizer access
 215  *      10      *16             unused
 216  *      11      *16             unused
 217  *      12      *16             unused
 218  *      13      *16             unused
 219  *      14      *16             unused
 220  *      15      *16             unused
 221  */
 222
 223 static struct sound_unit *chains[SOUND_STEP];
 224
 225 /**
 226  *      register_sound_special_device - register a special sound node
 227  *      @fops: File operations for the driver
 228  *      @unit: Unit number to allocate
 229  *      @dev: device pointer
 230  *
 231  *      Allocate a special sound device by minor number from the sound
 232  *      subsystem. The allocated number is returned on succes. On failure
 233  *      a negative error code is returned.
 234  */
 235
 236 int register_sound_special_device(const struct file_operations *fops, int unit,
 237                                   struct device *dev)
 238 {
 239         const int chain = unit % SOUND_STEP;
 240         int max_unit = 128 + chain;
 241         const char *name;
 242         char _name[16];
 243
 244         switch (chain) {
 245             case 0:
 246                 name = "mixer";
 247                 break;
 248             case 1:
 249                 name = "sequencer";
 250                 if (unit >= SOUND_STEP)
 251                         goto __unknown;
 252                 max_unit = unit + 1;
 253                 break;
 254             case 2:
 255                 name = "midi";
 256                 break;
 257             case 3:
 258                 name = "dsp";
 259                 break;
 260             case 4:
 261                 name = "audio";
 262                 break;
 263             case 8:
 264                 name = "sequencer2";
 265                 if (unit >= SOUND_STEP)
 266                         goto __unknown;
 267                 max_unit = unit + 1;
 268                 break;
 269             case 9:
 270                 name = "dmmidi";
 271                 break;
 272             case 10:
 273                 name = "dmfm";
 274                 break;
 275             case 12:
 276                 name = "adsp";
 277                 break;
 278             case 13:
 279                 name = "amidi";
 280                 break;
 281             case 14:
 282                 name = "admmidi";
 283                 break;
 284             default:
 285                 {
 286                     __unknown:
 287                         sprintf(_name, "unknown%d", chain);
 288                         if (unit >= SOUND_STEP)
 289                                 strcat(_name, "-");
 290                         name = _name;
 291                 }
 292                 break;
 293         }
 294         return sound_insert_unit(&chains[chain], fops, -1, unit, max_unit,
 295                                  name, S_IRUSR | S_IWUSR, dev);
 296 }
 297
 298 EXPORT_SYMBOL(register_sound_special_device);
 299
 300 int register_sound_special(const struct file_operations *fops, int unit)
 301 {
 302         return register_sound_special_device(fops, unit, NULL);
 303 }
 304
 305 EXPORT_SYMBOL(register_sound_special);
 306
 307 /**
 308  *      register_sound_mixer - register a mixer device
 309  *      @fops: File operations for the driver
 310  *      @dev: Unit number to allocate
 311  *
 312  *      Allocate a mixer device. Unit is the number of the mixer requested.
 313  *      Pass -1 to request the next free mixer unit. On success the allocated
 314  *      number is returned, on failure a negative error code is returned.
 315  */
 316
 317 int register_sound_mixer(const struct file_operations *fops, int dev)
 318 {
 319         return sound_insert_unit(&chains[0], fops, dev, 0, 128,
 320                                  "mixer", S_IRUSR | S_IWUSR, NULL);
 321 }
 322
 323 EXPORT_SYMBOL(register_sound_mixer);
 324
 325 /**
 326  *      register_sound_midi - register a midi device
 327  *      @fops: File operations for the driver
 328  *      @dev: Unit number to allocate
 329  *
 330  *      Allocate a midi device. Unit is the number of the midi device requested.
 331  *      Pass -1 to request the next free midi unit. On success the allocated
 332  *      number is returned, on failure a negative error code is returned.
 333  */
 334
 335 int register_sound_midi(const struct file_operations *fops, int dev)
 336 {
 337         return sound_insert_unit(&chains[2], fops, dev, 2, 130,
 338                                  "midi", S_IRUSR | S_IWUSR, NULL);
 339 }
 340
 341 EXPORT_SYMBOL(register_sound_midi);
 342
 343 /*
 344  *      DSP's are registered as a triple. Register only one and cheat
 345  *      in open - see below.
 346  */
 347
 348 /**
 349  *      register_sound_dsp - register a DSP device
 350  *      @fops: File operations for the driver
 351  *      @dev: Unit number to allocate
 352  *
 353  *      Allocate a DSP device. Unit is the number of the DSP requested.
 354  *      Pass -1 to request the next free DSP unit. On success the allocated
 355  *      number is returned, on failure a negative error code is returned.
 356  *
 357  *      This function allocates both the audio and dsp device entries together
 358  *      and will always allocate them as a matching pair - eg dsp3/audio3
 359  */
 360
 361 int register_sound_dsp(const struct file_operations *fops, int dev)
 362 {
 363         return sound_insert_unit(&chains[3], fops, dev, 3, 131,
 364                                  "dsp", S_IWUSR | S_IRUSR, NULL);
 365 }
 366
 367 EXPORT_SYMBOL(register_sound_dsp);
 368
 369 /**
 370  *      unregister_sound_special - unregister a special sound device
 371  *      @unit: unit number to allocate
 372  *
 373  *      Release a sound device that was allocated with
 374  *      register_sound_special(). The unit passed is the return value from
 375  *      the register function.
 376  */
 377
 378
 379 void unregister_sound_special(int unit)
 380 {
 381         sound_remove_unit(&chains[unit % SOUND_STEP], unit);
 382 }
 383
 384 EXPORT_SYMBOL(unregister_sound_special);
 385
 386 /**
 387  *      unregister_sound_mixer - unregister a mixer
 388  *      @unit: unit number to allocate
 389  *
 390  *      Release a sound device that was allocated with register_sound_mixer().
 391  *      The unit passed is the return value from the register function.
 392  */
 393
 394 void unregister_sound_mixer(int unit)
 395 {
 396         sound_remove_unit(&chains[0], unit);
 397 }
 398
 399 EXPORT_SYMBOL(unregister_sound_mixer);
 400
 401 /**
 402  *      unregister_sound_midi - unregister a midi device
 403  *      @unit: unit number to allocate
 404  *
 405  *      Release a sound device that was allocated with register_sound_midi().
 406  *      The unit passed is the return value from the register function.
 407  */
 408
 409 void unregister_sound_midi(int unit)
 410 {
 411         return sound_remove_unit(&chains[2], unit);
 412 }
 413
 414 EXPORT_SYMBOL(unregister_sound_midi);
 415
 416 /**
 417  *      unregister_sound_dsp - unregister a DSP device
 418  *      @unit: unit number to allocate
 419  *
 420  *      Release a sound device that was allocated with register_sound_dsp().
 421  *      The unit passed is the return value from the register function.
 422  *
 423  *      Both of the allocated units are released together automatically.
 424  */
 425
 426 void unregister_sound_dsp(int unit)
 427 {
 428         return sound_remove_unit(&chains[3], unit);
 429 }
 430
 431
 432 EXPORT_SYMBOL(unregister_sound_dsp);
 433
 434 /*
 435  *      Now our file operations
 436  */
 437
 438 static int soundcore_open(struct inode *, struct file *);
 439
 440 static const struct file_operations soundcore_fops=
 441 {
 442         /* We must have an owner or the module locking fails */
 443         .owner  = THIS_MODULE,
 444         .open   = soundcore_open,
 445 };
 446
 447 static struct sound_unit *__look_for_unit(int chain, int unit)
 448 {
 449         struct sound_unit *s;
 450
 451         s=chains[chain];
 452         while(s && s->unit_minor <= unit)
 453         {
 454                 if(s->unit_minor==unit)
 455                         return s;
 456                 s=s->next;
 457         }
 458         return NULL;
 459 }
 460
 461 int soundcore_open(struct inode *inode, struct file *file)
 462 {
 463         int chain;
 464         int unit = iminor(inode);
 465         struct sound_unit *s;
 466         const struct file_operations *new_fops = NULL;
 467
 468         lock_kernel ();
 469
 470         chain=unit&0x0F;
 471         if(chain==4 || chain==5)        /* dsp/audio/dsp16 */
 472         {
 473                 unit&=0xF0;
 474                 unit|=3;
 475                 chain=3;
 476         }
 477
 478         spin_lock(&sound_loader_lock);
 479         s = __look_for_unit(chain, unit);
 480         if (s)
 481                 new_fops = fops_get(s->unit_fops);
 482         if (!new_fops) {
 483                 spin_unlock(&sound_loader_lock);
 484                 /*
 485                  *  Please, don't change this order or code.
 486                  *  For ALSA slot means soundcard and OSS emulation code
 487                  *  comes as add-on modules which aren't depend on
 488                  *  ALSA toplevel modules for soundcards, thus we need
 489                  *  load them at first.   [Jaroslav Kysela <perex@jcu.cz>]
 490                  */
 491                 request_module("sound-slot-%i", unit>>4);
 492                 request_module("sound-service-%i-%i", unit>>4, chain);
 493                 spin_lock(&sound_loader_lock);
 494                 s = __look_for_unit(chain, unit);
 495                 if (s)
 496                         new_fops = fops_get(s->unit_fops);
 497         }
 498         if (new_fops) {
 499                 /*
 500                  * We rely upon the fact that we can't be unloaded while the
 501                  * subdriver is there, so if ->open() is successful we can
 502                  * safely drop the reference counter and if it is not we can
 503                  * revert to old ->f_op. Ugly, indeed, but that's the cost of
 504                  * switching ->f_op in the first place.
 505                  */
 506                 int err = 0;
 507                 const struct file_operations *old_fops = file->f_op;
 508                 file->f_op = new_fops;
 509                 spin_unlock(&sound_loader_lock);
 510                 if(file->f_op->open)
 511                         err = file->f_op->open(inode,file);
 512                 if (err) {
 513                         fops_put(file->f_op);
 514                         file->f_op = fops_get(old_fops);
 515                 }
 516                 fops_put(old_fops);
 517                 unlock_kernel();
 518                 return err;
 519         }
 520         spin_unlock(&sound_loader_lock);
 521         unlock_kernel();
 522         return -ENODEV;
 523 }
 524
 525 MODULE_DESCRIPTION("Core sound module");
 526 MODULE_AUTHOR("Alan Cox");
 527 MODULE_LICENSE("GPL");
 528 MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);
 529
 530 static void __exit cleanup_soundcore(void)
 531 {
 532         /* We have nothing to really do here - we know the lists must be
 533            empty */
 534         unregister_chrdev(SOUND_MAJOR, "sound");
 535         class_destroy(sound_class);
 536 }
 537
 538 static int __init init_soundcore(void)
 539 {
 540         if (register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops)==-1) {
 541                 printk(KERN_ERR "soundcore: sound device already in use.\n");
 542                 return -EBUSY;
 543         }
 544         sound_class = class_create(THIS_MODULE, "sound");
 545         if (IS_ERR(sound_class))
 546                 return PTR_ERR(sound_class);
 547
 548         return 0;
 549 }
 550
 551 module_init(init_soundcore);
 552 module_exit(cleanup_soundcore);