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->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         if (new_fops) {
 630                 /*
 631                  * We rely upon the fact that we can't be unloaded while the
 632                  * subdriver is there, so if ->open() is successful we can
 633                  * safely drop the reference counter and if it is not we can
 634                  * revert to old ->f_op. Ugly, indeed, but that's the cost of
 635                  * switching ->f_op in the first place.
 636                  */
 637                 int err = 0;
 638                 const struct file_operations *old_fops = file->f_op;
 639                 file->f_op = new_fops;
 640                 spin_unlock(&sound_loader_lock);
 641
 642                 if (file->f_op->open)
 643                         err = file->f_op->open(inode,file);
 644
 645                 if (err) {
 646                         fops_put(file->f_op);
 647                         file->f_op = fops_get(old_fops);
 648                 }
 649
 650                 fops_put(old_fops);
 651                 return err;
 652         }
 653         spin_unlock(&sound_loader_lock);
 654         return -ENODEV;
 655 }
 656
 657 MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);
 658
 659 static void cleanup_oss_soundcore(void)
 660 {
 661         /* We have nothing to really do here - we know the lists must be
 662            empty */
 663         unregister_chrdev(SOUND_MAJOR, "sound");
 664 }
 665
 666 static int __init init_oss_soundcore(void)
 667 {
 668         if (preclaim_oss &&
 669             register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) == -1) {
 670                 printk(KERN_ERR "soundcore: sound device already in use.\n");
 671                 return -EBUSY;
 672         }
 673
 674         return 0;
 675 }
 676
 677 #endif /* CONFIG_SOUND_OSS_CORE */