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 /*
 123  * By default, OSS sound_core claims full legacy minor range (0-255)
 124  * of SOUND_MAJOR to trap open attempts to any sound minor and
 125  * requests modules using custom sound-slot/service-* module aliases.
 126  * The only benefit of doing this is allowing use of custom module
 127  * aliases instead of the standard char-major-* ones.  This behavior
 128  * prevents alternative OSS implementation and is scheduled to be
 129  * removed.
 130  *
 131  * CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss kernel
 132  * parameter are added to allow distros and developers to try and
 133  * switch to alternative implementations without needing to rebuild
 134  * the kernel in the meantime.  If preclaim_oss is non-zero, the
 135  * kernel will behave the same as before.  All SOUND_MAJOR minors are
 136  * preclaimed and the custom module aliases along with standard chrdev
 137  * ones are emitted if a missing device is opened.  If preclaim_oss is
 138  * zero, sound_core only grabs what's actually in use and for missing
 139  * devices only the standard chrdev aliases are requested.
 140  *
 141  * All these clutters are scheduled to be removed along with
 142  * sound-slot/service-* module aliases.
 143  */
 144 #ifdef CONFIG_SOUND_OSS_CORE_PRECLAIM
 145 static int preclaim_oss = 1;
 146 #else
 147 static int preclaim_oss = 0;
 148 #endif
 149
 150 module_param(preclaim_oss, int, 0444);
 151
 152 static int soundcore_open(struct inode *, struct file *);
 153
 154 static const struct file_operations soundcore_fops =
 155 {
 156         /* We must have an owner or the module locking fails */
 157         .owner  = THIS_MODULE,
 158         .open   = soundcore_open,
 159         .llseek = noop_llseek,
 160 };
 161
 162 /*
 163  *      Low level list operator. Scan the ordered list, find a hole and
 164  *      join into it. Called with the lock asserted
 165  */
 166
 167 static int __sound_insert_unit(struct sound_unit * s, struct sound_unit **list, const struct file_operations *fops, int index, int low, int top)
 168 {
 169         int n=low;
 170
 171         if (index < 0) {        /* first free */
 172
 173                 while (*list && (*list)->unit_minor<n)
 174                         list=&((*list)->next);
 175
 176                 while(n<top)
 177                 {
 178                         /* Found a hole ? */
 179                         if(*list==NULL || (*list)->unit_minor>n)
 180                                 break;
 181                         list=&((*list)->next);
 182                         n+=SOUND_STEP;
 183                 }
 184
 185                 if(n>=top)
 186                         return -ENOENT;
 187         } else {
 188                 n = low+(index*16);
 189                 while (*list) {
 190                         if ((*list)->unit_minor==n)
 191                                 return -EBUSY;
 192                         if ((*list)->unit_minor>n)
 193                                 break;
 194                         list=&((*list)->next);
 195                 }
 196         }
 197
 198         /*
 199          *      Fill it in
 200          */
 201
 202         s->unit_minor=n;
 203         s->unit_fops=fops;
 204
 205         /*
 206          *      Link it
 207          */
 208
 209         s->next=*list;
 210         *list=s;
 211
 212
 213         return n;
 214 }
 215
 216 /*
 217  *      Remove a node from the chain. Called with the lock asserted
 218  */
 219
 220 static struct sound_unit *__sound_remove_unit(struct sound_unit **list, int unit)
 221 {
 222         while(*list)
 223         {
 224                 struct sound_unit *p=*list;
 225                 if(p->unit_minor==unit)
 226                 {
 227                         *list=p->next;
 228                         return p;
 229                 }
 230                 list=&(p->next);
 231         }
 232         printk(KERN_ERR "Sound device %d went missing!\n", unit);
 233         return NULL;
 234 }
 235
 236 /*
 237  *      This lock guards the sound loader list.
 238  */
 239
 240 static DEFINE_SPINLOCK(sound_loader_lock);
 241
 242 /*
 243  *      Allocate the controlling structure and add it to the sound driver
 244  *      list. Acquires locks as needed
 245  */
 246
 247 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)
 248 {
 249         struct sound_unit *s = kmalloc(sizeof(*s), GFP_KERNEL);
 250         int r;
 251
 252         if (!s)
 253                 return -ENOMEM;
 254
 255         spin_lock(&sound_loader_lock);
 256 retry:
 257         r = __sound_insert_unit(s, list, fops, index, low, top);
 258         spin_unlock(&sound_loader_lock);
 259
 260         if (r < 0)
 261                 goto fail;
 262         else if (r < SOUND_STEP)
 263                 sprintf(s->name, "sound/%s", name);
 264         else
 265                 sprintf(s->name, "sound/%s%d", name, r / SOUND_STEP);
 266
 267         if (!preclaim_oss) {
 268                 /*
 269                  * Something else might have grabbed the minor.  If
 270                  * first free slot is requested, rescan with @low set
 271                  * to the next unit; otherwise, -EBUSY.
 272                  */
 273                 r = __register_chrdev(SOUND_MAJOR, s->unit_minor, 1, s->name,
 274                                       &soundcore_fops);
 275                 if (r < 0) {
 276                         spin_lock(&sound_loader_lock);
 277                         __sound_remove_unit(list, s->unit_minor);
 278                         if (index < 0) {
 279                                 low = s->unit_minor + SOUND_STEP;
 280                                 goto retry;
 281                         }
 282                         spin_unlock(&sound_loader_lock);
 283                         return -EBUSY;
 284                 }
 285         }
 286
 287         device_create(sound_class, dev, MKDEV(SOUND_MAJOR, s->unit_minor),
 288                       NULL, "%s", s->name+6);
 289         return s->unit_minor;
 290
 291 fail:
 292         kfree(s);
 293         return r;
 294 }
 295
 296 /*
 297  *      Remove a unit. Acquires locks as needed. The drivers MUST have
 298  *      completed the removal before their file operations become
 299  *      invalid.
 300  */
 301
 302 static void sound_remove_unit(struct sound_unit **list, int unit)
 303 {
 304         struct sound_unit *p;
 305
 306         spin_lock(&sound_loader_lock);
 307         p = __sound_remove_unit(list, unit);
 308         spin_unlock(&sound_loader_lock);
 309         if (p) {
 310                 if (!preclaim_oss)
 311                         __unregister_chrdev(SOUND_MAJOR, p->unit_minor, 1,
 312                                             p->name);
 313                 device_destroy(sound_class, MKDEV(SOUND_MAJOR, p->unit_minor));
 314                 kfree(p);
 315         }
 316 }
 317
 318 /*
 319  *      Allocations
 320  *
 321  *      0       *16             Mixers
 322  *      1       *8              Sequencers
 323  *      2       *16             Midi
 324  *      3       *16             DSP
 325  *      4       *16             SunDSP
 326  *      5       *16             DSP16
 327  *      6       --              sndstat (obsolete)
 328  *      7       *16             unused
 329  *      8       --              alternate sequencer (see above)
 330  *      9       *16             raw synthesizer access
 331  *      10      *16             unused
 332  *      11      *16             unused
 333  *      12      *16             unused
 334  *      13      *16             unused
 335  *      14      *16             unused
 336  *      15      *16             unused
 337  */
 338
 339 static struct sound_unit *chains[SOUND_STEP];
 340
 341 /**
 342  *      register_sound_special_device - register a special sound node
 343  *      @fops: File operations for the driver
 344  *      @unit: Unit number to allocate
 345  *      @dev: device pointer
 346  *
 347  *      Allocate a special sound device by minor number from the sound
 348  *      subsystem.
 349  *
 350  *      Return: The allocated number is returned on success. On failure,
 351  *      a negative error code is returned.
 352  */
 353
 354 int register_sound_special_device(const struct file_operations *fops, int unit,
 355                                   struct device *dev)
 356 {
 357         const int chain = unit % SOUND_STEP;
 358         int max_unit = 256;
 359         const char *name;
 360         char _name[16];
 361
 362         switch (chain) {
 363             case 0:
 364                 name = "mixer";
 365                 break;
 366             case 1:
 367                 name = "sequencer";
 368                 if (unit >= SOUND_STEP)
 369                         goto __unknown;
 370                 max_unit = unit + 1;
 371                 break;
 372             case 2:
 373                 name = "midi";
 374                 break;
 375             case 3:
 376                 name = "dsp";
 377                 break;
 378             case 4:
 379                 name = "audio";
 380                 break;
 381             case 5:
 382                 name = "dspW";
 383                 break;
 384             case 8:
 385                 name = "sequencer2";
 386                 if (unit >= SOUND_STEP)
 387                         goto __unknown;
 388                 max_unit = unit + 1;
 389                 break;
 390             case 9:
 391                 name = "dmmidi";
 392                 break;
 393             case 10:
 394                 name = "dmfm";
 395                 break;
 396             case 12:
 397                 name = "adsp";
 398                 break;
 399             case 13:
 400                 name = "amidi";
 401                 break;
 402             case 14:
 403                 name = "admmidi";
 404                 break;
 405             default:
 406                 {
 407                     __unknown:
 408                         sprintf(_name, "unknown%d", chain);
 409                         if (unit >= SOUND_STEP)
 410                                 strcat(_name, "-");
 411                         name = _name;
 412                 }
 413                 break;
 414         }
 415         return sound_insert_unit(&chains[chain], fops, -1, unit, max_unit,
 416                                  name, S_IRUSR | S_IWUSR, dev);
 417 }
 418
 419 EXPORT_SYMBOL(register_sound_special_device);
 420
 421 int register_sound_special(const struct file_operations *fops, int unit)
 422 {
 423         return register_sound_special_device(fops, unit, NULL);
 424 }
 425
 426 EXPORT_SYMBOL(register_sound_special);
 427
 428 /**
 429  *      register_sound_mixer - register a mixer device
 430  *      @fops: File operations for the driver
 431  *      @dev: Unit number to allocate
 432  *
 433  *      Allocate a mixer device. Unit is the number of the mixer requested.
 434  *      Pass -1 to request the next free mixer unit.
 435  *
 436  *      Return: On success, the allocated number is returned. On failure,
 437  *      a negative error code is returned.
 438  */
 439
 440 int register_sound_mixer(const struct file_operations *fops, int dev)
 441 {
 442         return sound_insert_unit(&chains[0], fops, dev, 0, 128,
 443                                  "mixer", S_IRUSR | S_IWUSR, NULL);
 444 }
 445
 446 EXPORT_SYMBOL(register_sound_mixer);
 447
 448 /*
 449  *      DSP's are registered as a triple. Register only one and cheat
 450  *      in open - see below.
 451  */
 452
 453 /**
 454  *      register_sound_dsp - register a DSP device
 455  *      @fops: File operations for the driver
 456  *      @dev: Unit number to allocate
 457  *
 458  *      Allocate a DSP device. Unit is the number of the DSP requested.
 459  *      Pass -1 to request the next free DSP unit.
 460  *
 461  *      This function allocates both the audio and dsp device entries together
 462  *      and will always allocate them as a matching pair - eg dsp3/audio3
 463  *
 464  *      Return: On success, the allocated number is returned. On failure,
 465  *      a negative error code is returned.
 466  */
 467
 468 int register_sound_dsp(const struct file_operations *fops, int dev)
 469 {
 470         return sound_insert_unit(&chains[3], fops, dev, 3, 131,
 471                                  "dsp", S_IWUSR | S_IRUSR, NULL);
 472 }
 473
 474 EXPORT_SYMBOL(register_sound_dsp);
 475
 476 /**
 477  *      unregister_sound_special - unregister a special sound device
 478  *      @unit: unit number to allocate
 479  *
 480  *      Release a sound device that was allocated with
 481  *      register_sound_special(). The unit passed is the return value from
 482  *      the register function.
 483  */
 484
 485
 486 void unregister_sound_special(int unit)
 487 {
 488         sound_remove_unit(&chains[unit % SOUND_STEP], unit);
 489 }
 490
 491 EXPORT_SYMBOL(unregister_sound_special);
 492
 493 /**
 494  *      unregister_sound_mixer - unregister a mixer
 495  *      @unit: unit number to allocate
 496  *
 497  *      Release a sound device that was allocated with register_sound_mixer().
 498  *      The unit passed is the return value from the register function.
 499  */
 500
 501 void unregister_sound_mixer(int unit)
 502 {
 503         sound_remove_unit(&chains[0], unit);
 504 }
 505
 506 EXPORT_SYMBOL(unregister_sound_mixer);
 507
 508 /**
 509  *      unregister_sound_dsp - unregister a DSP device
 510  *      @unit: unit number to allocate
 511  *
 512  *      Release a sound device that was allocated with register_sound_dsp().
 513  *      The unit passed is the return value from the register function.
 514  *
 515  *      Both of the allocated units are released together automatically.
 516  */
 517
 518 void unregister_sound_dsp(int unit)
 519 {
 520         sound_remove_unit(&chains[3], unit);
 521 }
 522
 523
 524 EXPORT_SYMBOL(unregister_sound_dsp);
 525
 526 static struct sound_unit *__look_for_unit(int chain, int unit)
 527 {
 528         struct sound_unit *s;
 529
 530         s=chains[chain];
 531         while(s && s->unit_minor <= unit)
 532         {
 533                 if(s->unit_minor==unit)
 534                         return s;
 535                 s=s->next;
 536         }
 537         return NULL;
 538 }
 539
 540 static int soundcore_open(struct inode *inode, struct file *file)
 541 {
 542         int chain;
 543         int unit = iminor(inode);
 544         struct sound_unit *s;
 545         const struct file_operations *new_fops = NULL;
 546
 547         chain=unit&0x0F;
 548         if(chain==4 || chain==5)        /* dsp/audio/dsp16 */
 549         {
 550                 unit&=0xF0;
 551                 unit|=3;
 552                 chain=3;
 553         }
 554
 555         spin_lock(&sound_loader_lock);
 556         s = __look_for_unit(chain, unit);
 557         if (s)
 558                 new_fops = fops_get(s->unit_fops);
 559         if (preclaim_oss && !new_fops) {
 560                 spin_unlock(&sound_loader_lock);
 561
 562                 /*
 563                  *  Please, don't change this order or code.
 564                  *  For ALSA slot means soundcard and OSS emulation code
 565                  *  comes as add-on modules which aren't depend on
 566                  *  ALSA toplevel modules for soundcards, thus we need
 567                  *  load them at first.   [Jaroslav Kysela <perex@jcu.cz>]
 568                  */
 569                 request_module("sound-slot-%i", unit>>4);
 570                 request_module("sound-service-%i-%i", unit>>4, chain);
 571
 572                 /*
 573                  * sound-slot/service-* module aliases are scheduled
 574                  * for removal in favor of the standard char-major-*
 575                  * module aliases.  For the time being, generate both
 576                  * the legacy and standard module aliases to ease
 577                  * transition.
 578                  */
 579                 if (request_module("char-major-%d-%d", SOUND_MAJOR, unit) > 0)
 580                         request_module("char-major-%d", SOUND_MAJOR);
 581
 582                 spin_lock(&sound_loader_lock);
 583                 s = __look_for_unit(chain, unit);
 584                 if (s)
 585                         new_fops = fops_get(s->unit_fops);
 586         }
 587         spin_unlock(&sound_loader_lock);
 588         if (new_fops) {
 589                 /*
 590                  * We rely upon the fact that we can't be unloaded while the
 591                  * subdriver is there.
 592                  */
 593                 int err = 0;
 594                 replace_fops(file, new_fops);
 595
 596                 if (file->f_op->open)
 597                         err = file->f_op->open(inode,file);
 598
 599                 return err;
 600         }
 601         return -ENODEV;
 602 }
 603
 604 MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);
 605
 606 static void cleanup_oss_soundcore(void)
 607 {
 608         /* We have nothing to really do here - we know the lists must be
 609            empty */
 610         unregister_chrdev(SOUND_MAJOR, "sound");
 611 }
 612
 613 static int __init init_oss_soundcore(void)
 614 {
 615         if (preclaim_oss &&
 616             register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) < 0) {
 617                 printk(KERN_ERR "soundcore: sound device already in use.\n");
 618                 return -EBUSY;
 619         }
 620
 621         return 0;
 622 }
 623
 624 #endif /* CONFIG_SOUND_OSS_CORE */