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, mode_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.  Please take a look at
 150  * feature-removal-schedule.txt for details.
 151  */
 152 #ifdef CONFIG_SOUND_OSS_CORE_PRECLAIM
 153 static int preclaim_oss = 1;
 154 #else
 155 static int preclaim_oss = 0;
 156 #endif
 157
 158 module_param(preclaim_oss, int, 0444);
 159
 160 static int soundcore_open(struct inode *, struct file *);
 161
 162 static const struct file_operations soundcore_fops =
 163 {
 164         /* We must have an owner or the module locking fails */
 165         .owner  = THIS_MODULE,
 166         .open   = soundcore_open,
 167         .llseek = noop_llseek,
 168 };
 169
 170 /*
 171  *      Low level list operator. Scan the ordered list, find a hole and
 172  *      join into it. Called with the lock asserted
 173  */
 174
 175 static int __sound_insert_unit(struct sound_unit * s, struct sound_unit **list, const struct file_operations *fops, int index, int low, int top)
 176 {
 177         int n=low;
 178
 179         if (index < 0) {        /* first free */
 180
 181                 while (*list && (*list)->unit_minor<n)
 182                         list=&((*list)->next);
 183
 184                 while(n<top)
 185                 {
 186                         /* Found a hole ? */
 187                         if(*list==NULL || (*list)->unit_minor>n)
 188                                 break;
 189                         list=&((*list)->next);
 190                         n+=SOUND_STEP;
 191                 }
 192
 193                 if(n>=top)
 194                         return -ENOENT;
 195         } else {
 196                 n = low+(index*16);
 197                 while (*list) {
 198                         if ((*list)->unit_minor==n)
 199                                 return -EBUSY;
 200                         if ((*list)->unit_minor>n)
 201                                 break;
 202                         list=&((*list)->next);
 203                 }
 204         }
 205
 206         /*
 207          *      Fill it in
 208          */
 209
 210         s->unit_minor=n;
 211         s->unit_fops=fops;
 212
 213         /*
 214          *      Link it
 215          */
 216
 217         s->next=*list;
 218         *list=s;
 219
 220
 221         return n;
 222 }
 223
 224 /*
 225  *      Remove a node from the chain. Called with the lock asserted
 226  */
 227
 228 static struct sound_unit *__sound_remove_unit(struct sound_unit **list, int unit)
 229 {
 230         while(*list)
 231         {
 232                 struct sound_unit *p=*list;
 233                 if(p->unit_minor==unit)
 234                 {
 235                         *list=p->next;
 236                         return p;
 237                 }
 238                 list=&(p->next);
 239         }
 240         printk(KERN_ERR "Sound device %d went missing!\n", unit);
 241         return NULL;
 242 }
 243
 244 /*
 245  *      This lock guards the sound loader list.
 246  */
 247
 248 static DEFINE_SPINLOCK(sound_loader_lock);
 249
 250 /*
 251  *      Allocate the controlling structure and add it to the sound driver
 252  *      list. Acquires locks as needed
 253  */
 254
 255 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)
 256 {
 257         struct sound_unit *s = kmalloc(sizeof(*s), GFP_KERNEL);
 258         int r;
 259
 260         if (!s)
 261                 return -ENOMEM;
 262
 263         spin_lock(&sound_loader_lock);
 264 retry:
 265         r = __sound_insert_unit(s, list, fops, index, low, top);
 266         spin_unlock(&sound_loader_lock);
 267
 268         if (r < 0)
 269                 goto fail;
 270         else if (r < SOUND_STEP)
 271                 sprintf(s->name, "sound/%s", name);
 272         else
 273                 sprintf(s->name, "sound/%s%d", name, r / SOUND_STEP);
 274
 275         if (!preclaim_oss) {
 276                 /*
 277                  * Something else might have grabbed the minor.  If
 278                  * first free slot is requested, rescan with @low set
 279                  * to the next unit; otherwise, -EBUSY.
 280                  */
 281                 r = __register_chrdev(SOUND_MAJOR, s->unit_minor, 1, s->name,
 282                                       &soundcore_fops);
 283                 if (r < 0) {
 284                         spin_lock(&sound_loader_lock);
 285                         __sound_remove_unit(list, s->unit_minor);
 286                         if (index < 0) {
 287                                 low = s->unit_minor + SOUND_STEP;
 288                                 goto retry;
 289                         }
 290                         spin_unlock(&sound_loader_lock);
 291                         return -EBUSY;
 292                 }
 293         }
 294
 295         device_create(sound_class, dev, MKDEV(SOUND_MAJOR, s->unit_minor),
 296                       NULL, s->name+6);
 297         return s->unit_minor;
 298
 299 fail:
 300         kfree(s);
 301         return r;
 302 }
 303
 304 /*
 305  *      Remove a unit. Acquires locks as needed. The drivers MUST have
 306  *      completed the removal before their file operations become
 307  *      invalid.
 308  */
 309
 310 static void sound_remove_unit(struct sound_unit **list, int unit)
 311 {
 312         struct sound_unit *p;
 313
 314         spin_lock(&sound_loader_lock);
 315         p = __sound_remove_unit(list, unit);
 316         spin_unlock(&sound_loader_lock);
 317         if (p) {
 318                 if (!preclaim_oss)
 319                         __unregister_chrdev(SOUND_MAJOR, p->unit_minor, 1,
 320                                             p->name);
 321                 device_destroy(sound_class, MKDEV(SOUND_MAJOR, p->unit_minor));
 322                 kfree(p);
 323         }
 324 }
 325
 326 /*
 327  *      Allocations
 328  *
 329  *      0       *16             Mixers
 330  *      1       *8              Sequencers
 331  *      2       *16             Midi
 332  *      3       *16             DSP
 333  *      4       *16             SunDSP
 334  *      5       *16             DSP16
 335  *      6       --              sndstat (obsolete)
 336  *      7       *16             unused
 337  *      8       --              alternate sequencer (see above)
 338  *      9       *16             raw synthesizer access
 339  *      10      *16             unused
 340  *      11      *16             unused
 341  *      12      *16             unused
 342  *      13      *16             unused
 343  *      14      *16             unused
 344  *      15      *16             unused
 345  */
 346
 347 static struct sound_unit *chains[SOUND_STEP];
 348
 349 /**
 350  *      register_sound_special_device - register a special sound node
 351  *      @fops: File operations for the driver
 352  *      @unit: Unit number to allocate
 353  *      @dev: device pointer
 354  *
 355  *      Allocate a special sound device by minor number from the sound
 356  *      subsystem. The allocated number is returned on success. On failure
 357  *      a negative error code is returned.
 358  */
 359
 360 int register_sound_special_device(const struct file_operations *fops, int unit,
 361                                   struct device *dev)
 362 {
 363         const int chain = unit % SOUND_STEP;
 364         int max_unit = 128 + chain;
 365         const char *name;
 366         char _name[16];
 367
 368         switch (chain) {
 369             case 0:
 370                 name = "mixer";
 371                 break;
 372             case 1:
 373                 name = "sequencer";
 374                 if (unit >= SOUND_STEP)
 375                         goto __unknown;
 376                 max_unit = unit + 1;
 377                 break;
 378             case 2:
 379                 name = "midi";
 380                 break;
 381             case 3:
 382                 name = "dsp";
 383                 break;
 384             case 4:
 385                 name = "audio";
 386                 break;
 387             case 8:
 388                 name = "sequencer2";
 389                 if (unit >= SOUND_STEP)
 390                         goto __unknown;
 391                 max_unit = unit + 1;
 392                 break;
 393             case 9:
 394                 name = "dmmidi";
 395                 break;
 396             case 10:
 397                 name = "dmfm";
 398                 break;
 399             case 12:
 400                 name = "adsp";
 401                 break;
 402             case 13:
 403                 name = "amidi";
 404                 break;
 405             case 14:
 406                 name = "admmidi";
 407                 break;
 408             default:
 409                 {
 410                     __unknown:
 411                         sprintf(_name, "unknown%d", chain);
 412                         if (unit >= SOUND_STEP)
 413                                 strcat(_name, "-");
 414                         name = _name;
 415                 }
 416                 break;
 417         }
 418         return sound_insert_unit(&chains[chain], fops, -1, unit, max_unit,
 419                                  name, S_IRUSR | S_IWUSR, dev);
 420 }
 421
 422 EXPORT_SYMBOL(register_sound_special_device);
 423
 424 int register_sound_special(const struct file_operations *fops, int unit)
 425 {
 426         return register_sound_special_device(fops, unit, NULL);
 427 }
 428
 429 EXPORT_SYMBOL(register_sound_special);
 430
 431 /**
 432  *      register_sound_mixer - register a mixer device
 433  *      @fops: File operations for the driver
 434  *      @dev: Unit number to allocate
 435  *
 436  *      Allocate a mixer device. Unit is the number of the mixer requested.
 437  *      Pass -1 to request the next free mixer unit. On success the allocated
 438  *      number is returned, on failure a negative error code is returned.
 439  */
 440
 441 int register_sound_mixer(const struct file_operations *fops, int dev)
 442 {
 443         return sound_insert_unit(&chains[0], fops, dev, 0, 128,
 444                                  "mixer", S_IRUSR | S_IWUSR, NULL);
 445 }
 446
 447 EXPORT_SYMBOL(register_sound_mixer);
 448
 449 /**
 450  *      register_sound_midi - register a midi device
 451  *      @fops: File operations for the driver
 452  *      @dev: Unit number to allocate
 453  *
 454  *      Allocate a midi device. Unit is the number of the midi device requested.
 455  *      Pass -1 to request the next free midi unit. On success the allocated
 456  *      number is returned, on failure a negative error code is returned.
 457  */
 458
 459 int register_sound_midi(const struct file_operations *fops, int dev)
 460 {
 461         return sound_insert_unit(&chains[2], fops, dev, 2, 130,
 462                                  "midi", S_IRUSR | S_IWUSR, NULL);
 463 }
 464
 465 EXPORT_SYMBOL(register_sound_midi);
 466
 467 /*
 468  *      DSP's are registered as a triple. Register only one and cheat
 469  *      in open - see below.
 470  */
 471
 472 /**
 473  *      register_sound_dsp - register a DSP device
 474  *      @fops: File operations for the driver
 475  *      @dev: Unit number to allocate
 476  *
 477  *      Allocate a DSP device. Unit is the number of the DSP requested.
 478  *      Pass -1 to request the next free DSP unit. On success the allocated
 479  *      number is returned, on failure a negative error code is returned.
 480  *
 481  *      This function allocates both the audio and dsp device entries together
 482  *      and will always allocate them as a matching pair - eg dsp3/audio3
 483  */
 484
 485 int register_sound_dsp(const struct file_operations *fops, int dev)
 486 {
 487         return sound_insert_unit(&chains[3], fops, dev, 3, 131,
 488                                  "dsp", S_IWUSR | S_IRUSR, NULL);
 489 }
 490
 491 EXPORT_SYMBOL(register_sound_dsp);
 492
 493 /**
 494  *      unregister_sound_special - unregister a special sound device
 495  *      @unit: unit number to allocate
 496  *
 497  *      Release a sound device that was allocated with
 498  *      register_sound_special(). The unit passed is the return value from
 499  *      the register function.
 500  */
 501
 502
 503 void unregister_sound_special(int unit)
 504 {
 505         sound_remove_unit(&chains[unit % SOUND_STEP], unit);
 506 }
 507
 508 EXPORT_SYMBOL(unregister_sound_special);
 509
 510 /**
 511  *      unregister_sound_mixer - unregister a mixer
 512  *      @unit: unit number to allocate
 513  *
 514  *      Release a sound device that was allocated with register_sound_mixer().
 515  *      The unit passed is the return value from the register function.
 516  */
 517
 518 void unregister_sound_mixer(int unit)
 519 {
 520         sound_remove_unit(&chains[0], unit);
 521 }
 522
 523 EXPORT_SYMBOL(unregister_sound_mixer);
 524
 525 /**
 526  *      unregister_sound_midi - unregister a midi device
 527  *      @unit: unit number to allocate
 528  *
 529  *      Release a sound device that was allocated with register_sound_midi().
 530  *      The unit passed is the return value from the register function.
 531  */
 532
 533 void unregister_sound_midi(int unit)
 534 {
 535         sound_remove_unit(&chains[2], unit);
 536 }
 537
 538 EXPORT_SYMBOL(unregister_sound_midi);
 539
 540 /**
 541  *      unregister_sound_dsp - unregister a DSP device
 542  *      @unit: unit number to allocate
 543  *
 544  *      Release a sound device that was allocated with register_sound_dsp().
 545  *      The unit passed is the return value from the register function.
 546  *
 547  *      Both of the allocated units are released together automatically.
 548  */
 549
 550 void unregister_sound_dsp(int unit)
 551 {
 552         sound_remove_unit(&chains[3], unit);
 553 }
 554
 555
 556 EXPORT_SYMBOL(unregister_sound_dsp);
 557
 558 static struct sound_unit *__look_for_unit(int chain, int unit)
 559 {
 560         struct sound_unit *s;
 561
 562         s=chains[chain];
 563         while(s && s->unit_minor <= unit)
 564         {
 565                 if(s->unit_minor==unit)
 566                         return s;
 567                 s=s->next;
 568         }
 569         return NULL;
 570 }
 571
 572 static int soundcore_open(struct inode *inode, struct file *file)
 573 {
 574         int chain;
 575         int unit = iminor(inode);
 576         struct sound_unit *s;
 577         const struct file_operations *new_fops = NULL;
 578
 579         chain=unit&0x0F;
 580         if(chain==4 || chain==5)        /* dsp/audio/dsp16 */
 581         {
 582                 unit&=0xF0;
 583                 unit|=3;
 584                 chain=3;
 585         }
 586
 587         spin_lock(&sound_loader_lock);
 588         s = __look_for_unit(chain, unit);
 589         if (s)
 590                 new_fops = fops_get(s->unit_fops);
 591         if (preclaim_oss && !new_fops) {
 592                 spin_unlock(&sound_loader_lock);
 593
 594                 /*
 595                  *  Please, don't change this order or code.
 596                  *  For ALSA slot means soundcard and OSS emulation code
 597                  *  comes as add-on modules which aren't depend on
 598                  *  ALSA toplevel modules for soundcards, thus we need
 599                  *  load them at first.   [Jaroslav Kysela <perex@jcu.cz>]
 600                  */
 601                 request_module("sound-slot-%i", unit>>4);
 602                 request_module("sound-service-%i-%i", unit>>4, chain);
 603
 604                 /*
 605                  * sound-slot/service-* module aliases are scheduled
 606                  * for removal in favor of the standard char-major-*
 607                  * module aliases.  For the time being, generate both
 608                  * the legacy and standard module aliases to ease
 609                  * transition.
 610                  */
 611                 if (request_module("char-major-%d-%d", SOUND_MAJOR, unit) > 0)
 612                         request_module("char-major-%d", SOUND_MAJOR);
 613
 614                 spin_lock(&sound_loader_lock);
 615                 s = __look_for_unit(chain, unit);
 616                 if (s)
 617                         new_fops = fops_get(s->unit_fops);
 618         }
 619         if (new_fops) {
 620                 /*
 621                  * We rely upon the fact that we can't be unloaded while the
 622                  * subdriver is there, so if ->open() is successful we can
 623                  * safely drop the reference counter and if it is not we can
 624                  * revert to old ->f_op. Ugly, indeed, but that's the cost of
 625                  * switching ->f_op in the first place.
 626                  */
 627                 int err = 0;
 628                 const struct file_operations *old_fops = file->f_op;
 629                 file->f_op = new_fops;
 630                 spin_unlock(&sound_loader_lock);
 631
 632                 if (file->f_op->open)
 633                         err = file->f_op->open(inode,file);
 634
 635                 if (err) {
 636                         fops_put(file->f_op);
 637                         file->f_op = fops_get(old_fops);
 638                 }
 639
 640                 fops_put(old_fops);
 641                 return err;
 642         }
 643         spin_unlock(&sound_loader_lock);
 644         return -ENODEV;
 645 }
 646
 647 MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);
 648
 649 static void cleanup_oss_soundcore(void)
 650 {
 651         /* We have nothing to really do here - we know the lists must be
 652            empty */
 653         unregister_chrdev(SOUND_MAJOR, "sound");
 654 }
 655
 656 static int __init init_oss_soundcore(void)
 657 {
 658         if (preclaim_oss &&
 659             register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) == -1) {
 660                 printk(KERN_ERR "soundcore: sound device already in use.\n");
 661                 return -EBUSY;
 662         }
 663
 664         return 0;
 665 }
 666
 667 #endif /* CONFIG_SOUND_OSS_CORE */