1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Sound core. This file is composed of two parts. sound_class 4 * which is common to both OSS and ALSA and OSS sound core which 5 * is used OSS or emulation of it. 6 */ 7 8 /* 9 * First, the common part. 10 */ 11 #include <linux/module.h> 12 #include <linux/device.h> 13 #include <linux/err.h> 14 #include <linux/kdev_t.h> 15 #include <linux/major.h> 16 #include <sound/core.h> 17 18 #ifdef CONFIG_SOUND_OSS_CORE 19 static int __init init_oss_soundcore(void); 20 static void cleanup_oss_soundcore(void); 21 #else 22 static inline int init_oss_soundcore(void) { return 0; } 23 static inline void cleanup_oss_soundcore(void) { } 24 #endif 25 26 struct class *sound_class; 27 EXPORT_SYMBOL(sound_class); 28 29 MODULE_DESCRIPTION("Core sound module"); 30 MODULE_AUTHOR("Alan Cox"); 31 MODULE_LICENSE("GPL"); 32 33 static char *sound_devnode(struct device *dev, umode_t *mode) 34 { 35 if (MAJOR(dev->devt) == SOUND_MAJOR) 36 return NULL; 37 return kasprintf(GFP_KERNEL, "snd/%s", dev_name(dev)); 38 } 39 40 static int __init init_soundcore(void) 41 { 42 int rc; 43 44 rc = init_oss_soundcore(); 45 if (rc) 46 return rc; 47 48 sound_class = class_create(THIS_MODULE, "sound"); 49 if (IS_ERR(sound_class)) { 50 cleanup_oss_soundcore(); 51 return PTR_ERR(sound_class); 52 } 53 54 sound_class->devnode = sound_devnode; 55 56 return 0; 57 } 58 59 static void __exit cleanup_soundcore(void) 60 { 61 cleanup_oss_soundcore(); 62 class_destroy(sound_class); 63 } 64 65 subsys_initcall(init_soundcore); 66 module_exit(cleanup_soundcore); 67 68 69 #ifdef CONFIG_SOUND_OSS_CORE 70 /* 71 * OSS sound core handling. Breaks out sound functions to submodules 72 * 73 * Author: Alan Cox <alan@lxorguk.ukuu.org.uk> 74 * 75 * Fixes: 76 * 77 * -------------------- 78 * 79 * Top level handler for the sound subsystem. Various devices can 80 * plug into this. The fact they don't all go via OSS doesn't mean 81 * they don't have to implement the OSS API. There is a lot of logic 82 * to keeping much of the OSS weight out of the code in a compatibility 83 * module, but it's up to the driver to rember to load it... 84 * 85 * The code provides a set of functions for registration of devices 86 * by type. This is done rather than providing a single call so that 87 * we can hide any future changes in the internals (eg when we go to 88 * 32bit dev_t) from the modules and their interface. 89 * 90 * Secondly we need to allocate the dsp, dsp16 and audio devices as 91 * one. Thus we misuse the chains a bit to simplify this. 92 * 93 * Thirdly to make it more fun and for 2.3.x and above we do all 94 * of this using fine grained locking. 95 * 96 * FIXME: we have to resolve modules and fine grained load/unload 97 * locking at some point in 2.3.x. 98 */ 99 100 #include <linux/init.h> 101 #include <linux/slab.h> 102 #include <linux/types.h> 103 #include <linux/kernel.h> 104 #include <linux/sound.h> 105 #include <linux/kmod.h> 106 107 #define SOUND_STEP 16 108 109 struct sound_unit 110 { 111 int unit_minor; 112 const struct file_operations *unit_fops; 113 struct sound_unit *next; 114 char name[32]; 115 }; 116 117 /* 118 * By default, OSS sound_core claims full legacy minor range (0-255) 119 * of SOUND_MAJOR to trap open attempts to any sound minor and 120 * requests modules using custom sound-slot/service-* module aliases. 121 * The only benefit of doing this is allowing use of custom module 122 * aliases instead of the standard char-major-* ones. This behavior 123 * prevents alternative OSS implementation and is scheduled to be 124 * removed. 125 * 126 * CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss kernel 127 * parameter are added to allow distros and developers to try and 128 * switch to alternative implementations without needing to rebuild 129 * the kernel in the meantime. If preclaim_oss is non-zero, the 130 * kernel will behave the same as before. All SOUND_MAJOR minors are 131 * preclaimed and the custom module aliases along with standard chrdev 132 * ones are emitted if a missing device is opened. If preclaim_oss is 133 * zero, sound_core only grabs what's actually in use and for missing 134 * devices only the standard chrdev aliases are requested. 135 * 136 * All these clutters are scheduled to be removed along with 137 * sound-slot/service-* module aliases. 138 */ 139 #ifdef CONFIG_SOUND_OSS_CORE_PRECLAIM 140 static int preclaim_oss = 1; 141 #else 142 static int preclaim_oss = 0; 143 #endif 144 145 module_param(preclaim_oss, int, 0444); 146 147 static int soundcore_open(struct inode *, struct file *); 148 149 static const struct file_operations soundcore_fops = 150 { 151 /* We must have an owner or the module locking fails */ 152 .owner = THIS_MODULE, 153 .open = soundcore_open, 154 .llseek = noop_llseek, 155 }; 156 157 /* 158 * Low level list operator. Scan the ordered list, find a hole and 159 * join into it. Called with the lock asserted 160 */ 161 162 static int __sound_insert_unit(struct sound_unit * s, struct sound_unit **list, const struct file_operations *fops, int index, int low, int top) 163 { 164 int n=low; 165 166 if (index < 0) { /* first free */ 167 168 while (*list && (*list)->unit_minor<n) 169 list=&((*list)->next); 170 171 while(n<top) 172 { 173 /* Found a hole ? */ 174 if(*list==NULL || (*list)->unit_minor>n) 175 break; 176 list=&((*list)->next); 177 n+=SOUND_STEP; 178 } 179 180 if(n>=top) 181 return -ENOENT; 182 } else { 183 n = low+(index*16); 184 while (*list) { 185 if ((*list)->unit_minor==n) 186 return -EBUSY; 187 if ((*list)->unit_minor>n) 188 break; 189 list=&((*list)->next); 190 } 191 } 192 193 /* 194 * Fill it in 195 */ 196 197 s->unit_minor=n; 198 s->unit_fops=fops; 199 200 /* 201 * Link it 202 */ 203 204 s->next=*list; 205 *list=s; 206 207 208 return n; 209 } 210 211 /* 212 * Remove a node from the chain. Called with the lock asserted 213 */ 214 215 static struct sound_unit *__sound_remove_unit(struct sound_unit **list, int unit) 216 { 217 while(*list) 218 { 219 struct sound_unit *p=*list; 220 if(p->unit_minor==unit) 221 { 222 *list=p->next; 223 return p; 224 } 225 list=&(p->next); 226 } 227 printk(KERN_ERR "Sound device %d went missing!\n", unit); 228 return NULL; 229 } 230 231 /* 232 * This lock guards the sound loader list. 233 */ 234 235 static DEFINE_SPINLOCK(sound_loader_lock); 236 237 /* 238 * Allocate the controlling structure and add it to the sound driver 239 * list. Acquires locks as needed 240 */ 241 242 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) 243 { 244 struct sound_unit *s = kmalloc(sizeof(*s), GFP_KERNEL); 245 int r; 246 247 if (!s) 248 return -ENOMEM; 249 250 spin_lock(&sound_loader_lock); 251 retry: 252 r = __sound_insert_unit(s, list, fops, index, low, top); 253 spin_unlock(&sound_loader_lock); 254 255 if (r < 0) 256 goto fail; 257 else if (r < SOUND_STEP) 258 sprintf(s->name, "sound/%s", name); 259 else 260 sprintf(s->name, "sound/%s%d", name, r / SOUND_STEP); 261 262 if (!preclaim_oss) { 263 /* 264 * Something else might have grabbed the minor. If 265 * first free slot is requested, rescan with @low set 266 * to the next unit; otherwise, -EBUSY. 267 */ 268 r = __register_chrdev(SOUND_MAJOR, s->unit_minor, 1, s->name, 269 &soundcore_fops); 270 if (r < 0) { 271 spin_lock(&sound_loader_lock); 272 __sound_remove_unit(list, s->unit_minor); 273 if (index < 0) { 274 low = s->unit_minor + SOUND_STEP; 275 goto retry; 276 } 277 spin_unlock(&sound_loader_lock); 278 r = -EBUSY; 279 goto fail; 280 } 281 } 282 283 device_create(sound_class, dev, MKDEV(SOUND_MAJOR, s->unit_minor), 284 NULL, "%s", s->name+6); 285 return s->unit_minor; 286 287 fail: 288 kfree(s); 289 return r; 290 } 291 292 /* 293 * Remove a unit. Acquires locks as needed. The drivers MUST have 294 * completed the removal before their file operations become 295 * invalid. 296 */ 297 298 static void sound_remove_unit(struct sound_unit **list, int unit) 299 { 300 struct sound_unit *p; 301 302 spin_lock(&sound_loader_lock); 303 p = __sound_remove_unit(list, unit); 304 spin_unlock(&sound_loader_lock); 305 if (p) { 306 if (!preclaim_oss) 307 __unregister_chrdev(SOUND_MAJOR, p->unit_minor, 1, 308 p->name); 309 device_destroy(sound_class, MKDEV(SOUND_MAJOR, p->unit_minor)); 310 kfree(p); 311 } 312 } 313 314 /* 315 * Allocations 316 * 317 * 0 *16 Mixers 318 * 1 *8 Sequencers 319 * 2 *16 Midi 320 * 3 *16 DSP 321 * 4 *16 SunDSP 322 * 5 *16 DSP16 323 * 6 -- sndstat (obsolete) 324 * 7 *16 unused 325 * 8 -- alternate sequencer (see above) 326 * 9 *16 raw synthesizer access 327 * 10 *16 unused 328 * 11 *16 unused 329 * 12 *16 unused 330 * 13 *16 unused 331 * 14 *16 unused 332 * 15 *16 unused 333 */ 334 335 static struct sound_unit *chains[SOUND_STEP]; 336 337 /** 338 * register_sound_special_device - register a special sound node 339 * @fops: File operations for the driver 340 * @unit: Unit number to allocate 341 * @dev: device pointer 342 * 343 * Allocate a special sound device by minor number from the sound 344 * subsystem. 345 * 346 * Return: The allocated number is returned on success. On failure, 347 * a negative error code is returned. 348 */ 349 350 int register_sound_special_device(const struct file_operations *fops, int unit, 351 struct device *dev) 352 { 353 const int chain = unit % SOUND_STEP; 354 int max_unit = 256; 355 const char *name; 356 char _name[16]; 357 358 switch (chain) { 359 case 0: 360 name = "mixer"; 361 break; 362 case 1: 363 name = "sequencer"; 364 if (unit >= SOUND_STEP) 365 goto __unknown; 366 max_unit = unit + 1; 367 break; 368 case 2: 369 name = "midi"; 370 break; 371 case 3: 372 name = "dsp"; 373 break; 374 case 4: 375 name = "audio"; 376 break; 377 case 5: 378 name = "dspW"; 379 break; 380 case 8: 381 name = "sequencer2"; 382 if (unit >= SOUND_STEP) 383 goto __unknown; 384 max_unit = unit + 1; 385 break; 386 case 9: 387 name = "dmmidi"; 388 break; 389 case 10: 390 name = "dmfm"; 391 break; 392 case 12: 393 name = "adsp"; 394 break; 395 case 13: 396 name = "amidi"; 397 break; 398 case 14: 399 name = "admmidi"; 400 break; 401 default: 402 { 403 __unknown: 404 sprintf(_name, "unknown%d", chain); 405 if (unit >= SOUND_STEP) 406 strcat(_name, "-"); 407 name = _name; 408 } 409 break; 410 } 411 return sound_insert_unit(&chains[chain], fops, -1, unit, max_unit, 412 name, 0600, dev); 413 } 414 415 EXPORT_SYMBOL(register_sound_special_device); 416 417 int register_sound_special(const struct file_operations *fops, int unit) 418 { 419 return register_sound_special_device(fops, unit, NULL); 420 } 421 422 EXPORT_SYMBOL(register_sound_special); 423 424 /** 425 * register_sound_mixer - register a mixer device 426 * @fops: File operations for the driver 427 * @dev: Unit number to allocate 428 * 429 * Allocate a mixer device. Unit is the number of the mixer requested. 430 * Pass -1 to request the next free mixer unit. 431 * 432 * Return: On success, the allocated number is returned. On failure, 433 * a negative error code is returned. 434 */ 435 436 int register_sound_mixer(const struct file_operations *fops, int dev) 437 { 438 return sound_insert_unit(&chains[0], fops, dev, 0, 128, 439 "mixer", 0600, NULL); 440 } 441 442 EXPORT_SYMBOL(register_sound_mixer); 443 444 /* 445 * DSP's are registered as a triple. Register only one and cheat 446 * in open - see below. 447 */ 448 449 /** 450 * register_sound_dsp - register a DSP device 451 * @fops: File operations for the driver 452 * @dev: Unit number to allocate 453 * 454 * Allocate a DSP device. Unit is the number of the DSP requested. 455 * Pass -1 to request the next free DSP unit. 456 * 457 * This function allocates both the audio and dsp device entries together 458 * and will always allocate them as a matching pair - eg dsp3/audio3 459 * 460 * Return: On success, the allocated number is returned. On failure, 461 * a negative error code is returned. 462 */ 463 464 int register_sound_dsp(const struct file_operations *fops, int dev) 465 { 466 return sound_insert_unit(&chains[3], fops, dev, 3, 131, 467 "dsp", 0600, NULL); 468 } 469 470 EXPORT_SYMBOL(register_sound_dsp); 471 472 /** 473 * unregister_sound_special - unregister a special sound device 474 * @unit: unit number to allocate 475 * 476 * Release a sound device that was allocated with 477 * register_sound_special(). The unit passed is the return value from 478 * the register function. 479 */ 480 481 482 void unregister_sound_special(int unit) 483 { 484 sound_remove_unit(&chains[unit % SOUND_STEP], unit); 485 } 486 487 EXPORT_SYMBOL(unregister_sound_special); 488 489 /** 490 * unregister_sound_mixer - unregister a mixer 491 * @unit: unit number to allocate 492 * 493 * Release a sound device that was allocated with register_sound_mixer(). 494 * The unit passed is the return value from the register function. 495 */ 496 497 void unregister_sound_mixer(int unit) 498 { 499 sound_remove_unit(&chains[0], unit); 500 } 501 502 EXPORT_SYMBOL(unregister_sound_mixer); 503 504 /** 505 * unregister_sound_dsp - unregister a DSP device 506 * @unit: unit number to allocate 507 * 508 * Release a sound device that was allocated with register_sound_dsp(). 509 * The unit passed is the return value from the register function. 510 * 511 * Both of the allocated units are released together automatically. 512 */ 513 514 void unregister_sound_dsp(int unit) 515 { 516 sound_remove_unit(&chains[3], unit); 517 } 518 519 520 EXPORT_SYMBOL(unregister_sound_dsp); 521 522 static struct sound_unit *__look_for_unit(int chain, int unit) 523 { 524 struct sound_unit *s; 525 526 s=chains[chain]; 527 while(s && s->unit_minor <= unit) 528 { 529 if(s->unit_minor==unit) 530 return s; 531 s=s->next; 532 } 533 return NULL; 534 } 535 536 static int soundcore_open(struct inode *inode, struct file *file) 537 { 538 int chain; 539 int unit = iminor(inode); 540 struct sound_unit *s; 541 const struct file_operations *new_fops = NULL; 542 543 chain=unit&0x0F; 544 if(chain==4 || chain==5) /* dsp/audio/dsp16 */ 545 { 546 unit&=0xF0; 547 unit|=3; 548 chain=3; 549 } 550 551 spin_lock(&sound_loader_lock); 552 s = __look_for_unit(chain, unit); 553 if (s) 554 new_fops = fops_get(s->unit_fops); 555 if (preclaim_oss && !new_fops) { 556 spin_unlock(&sound_loader_lock); 557 558 /* 559 * Please, don't change this order or code. 560 * For ALSA slot means soundcard and OSS emulation code 561 * comes as add-on modules which aren't depend on 562 * ALSA toplevel modules for soundcards, thus we need 563 * load them at first. [Jaroslav Kysela <perex@jcu.cz>] 564 */ 565 request_module("sound-slot-%i", unit>>4); 566 request_module("sound-service-%i-%i", unit>>4, chain); 567 568 /* 569 * sound-slot/service-* module aliases are scheduled 570 * for removal in favor of the standard char-major-* 571 * module aliases. For the time being, generate both 572 * the legacy and standard module aliases to ease 573 * transition. 574 */ 575 if (request_module("char-major-%d-%d", SOUND_MAJOR, unit) > 0) 576 request_module("char-major-%d", SOUND_MAJOR); 577 578 spin_lock(&sound_loader_lock); 579 s = __look_for_unit(chain, unit); 580 if (s) 581 new_fops = fops_get(s->unit_fops); 582 } 583 spin_unlock(&sound_loader_lock); 584 if (new_fops) { 585 /* 586 * We rely upon the fact that we can't be unloaded while the 587 * subdriver is there. 588 */ 589 int err = 0; 590 replace_fops(file, new_fops); 591 592 if (file->f_op->open) 593 err = file->f_op->open(inode,file); 594 595 return err; 596 } 597 return -ENODEV; 598 } 599 600 MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR); 601 602 static void cleanup_oss_soundcore(void) 603 { 604 /* We have nothing to really do here - we know the lists must be 605 empty */ 606 unregister_chrdev(SOUND_MAJOR, "sound"); 607 } 608 609 static int __init init_oss_soundcore(void) 610 { 611 if (preclaim_oss && 612 register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) < 0) { 613 printk(KERN_ERR "soundcore: sound device already in use.\n"); 614 return -EBUSY; 615 } 616 617 return 0; 618 } 619 620 #endif /* CONFIG_SOUND_OSS_CORE */ 621