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 return -EBUSY; 279 } 280 } 281 282 device_create(sound_class, dev, MKDEV(SOUND_MAJOR, s->unit_minor), 283 NULL, "%s", s->name+6); 284 return s->unit_minor; 285 286 fail: 287 kfree(s); 288 return r; 289 } 290 291 /* 292 * Remove a unit. Acquires locks as needed. The drivers MUST have 293 * completed the removal before their file operations become 294 * invalid. 295 */ 296 297 static void sound_remove_unit(struct sound_unit **list, int unit) 298 { 299 struct sound_unit *p; 300 301 spin_lock(&sound_loader_lock); 302 p = __sound_remove_unit(list, unit); 303 spin_unlock(&sound_loader_lock); 304 if (p) { 305 if (!preclaim_oss) 306 __unregister_chrdev(SOUND_MAJOR, p->unit_minor, 1, 307 p->name); 308 device_destroy(sound_class, MKDEV(SOUND_MAJOR, p->unit_minor)); 309 kfree(p); 310 } 311 } 312 313 /* 314 * Allocations 315 * 316 * 0 *16 Mixers 317 * 1 *8 Sequencers 318 * 2 *16 Midi 319 * 3 *16 DSP 320 * 4 *16 SunDSP 321 * 5 *16 DSP16 322 * 6 -- sndstat (obsolete) 323 * 7 *16 unused 324 * 8 -- alternate sequencer (see above) 325 * 9 *16 raw synthesizer access 326 * 10 *16 unused 327 * 11 *16 unused 328 * 12 *16 unused 329 * 13 *16 unused 330 * 14 *16 unused 331 * 15 *16 unused 332 */ 333 334 static struct sound_unit *chains[SOUND_STEP]; 335 336 /** 337 * register_sound_special_device - register a special sound node 338 * @fops: File operations for the driver 339 * @unit: Unit number to allocate 340 * @dev: device pointer 341 * 342 * Allocate a special sound device by minor number from the sound 343 * subsystem. 344 * 345 * Return: The allocated number is returned on success. On failure, 346 * a negative error code is returned. 347 */ 348 349 int register_sound_special_device(const struct file_operations *fops, int unit, 350 struct device *dev) 351 { 352 const int chain = unit % SOUND_STEP; 353 int max_unit = 256; 354 const char *name; 355 char _name[16]; 356 357 switch (chain) { 358 case 0: 359 name = "mixer"; 360 break; 361 case 1: 362 name = "sequencer"; 363 if (unit >= SOUND_STEP) 364 goto __unknown; 365 max_unit = unit + 1; 366 break; 367 case 2: 368 name = "midi"; 369 break; 370 case 3: 371 name = "dsp"; 372 break; 373 case 4: 374 name = "audio"; 375 break; 376 case 5: 377 name = "dspW"; 378 break; 379 case 8: 380 name = "sequencer2"; 381 if (unit >= SOUND_STEP) 382 goto __unknown; 383 max_unit = unit + 1; 384 break; 385 case 9: 386 name = "dmmidi"; 387 break; 388 case 10: 389 name = "dmfm"; 390 break; 391 case 12: 392 name = "adsp"; 393 break; 394 case 13: 395 name = "amidi"; 396 break; 397 case 14: 398 name = "admmidi"; 399 break; 400 default: 401 { 402 __unknown: 403 sprintf(_name, "unknown%d", chain); 404 if (unit >= SOUND_STEP) 405 strcat(_name, "-"); 406 name = _name; 407 } 408 break; 409 } 410 return sound_insert_unit(&chains[chain], fops, -1, unit, max_unit, 411 name, 0600, dev); 412 } 413 414 EXPORT_SYMBOL(register_sound_special_device); 415 416 int register_sound_special(const struct file_operations *fops, int unit) 417 { 418 return register_sound_special_device(fops, unit, NULL); 419 } 420 421 EXPORT_SYMBOL(register_sound_special); 422 423 /** 424 * register_sound_mixer - register a mixer device 425 * @fops: File operations for the driver 426 * @dev: Unit number to allocate 427 * 428 * Allocate a mixer device. Unit is the number of the mixer requested. 429 * Pass -1 to request the next free mixer unit. 430 * 431 * Return: On success, the allocated number is returned. On failure, 432 * a negative error code is returned. 433 */ 434 435 int register_sound_mixer(const struct file_operations *fops, int dev) 436 { 437 return sound_insert_unit(&chains[0], fops, dev, 0, 128, 438 "mixer", 0600, NULL); 439 } 440 441 EXPORT_SYMBOL(register_sound_mixer); 442 443 /* 444 * DSP's are registered as a triple. Register only one and cheat 445 * in open - see below. 446 */ 447 448 /** 449 * register_sound_dsp - register a DSP device 450 * @fops: File operations for the driver 451 * @dev: Unit number to allocate 452 * 453 * Allocate a DSP device. Unit is the number of the DSP requested. 454 * Pass -1 to request the next free DSP unit. 455 * 456 * This function allocates both the audio and dsp device entries together 457 * and will always allocate them as a matching pair - eg dsp3/audio3 458 * 459 * Return: On success, the allocated number is returned. On failure, 460 * a negative error code is returned. 461 */ 462 463 int register_sound_dsp(const struct file_operations *fops, int dev) 464 { 465 return sound_insert_unit(&chains[3], fops, dev, 3, 131, 466 "dsp", 0600, NULL); 467 } 468 469 EXPORT_SYMBOL(register_sound_dsp); 470 471 /** 472 * unregister_sound_special - unregister a special sound device 473 * @unit: unit number to allocate 474 * 475 * Release a sound device that was allocated with 476 * register_sound_special(). The unit passed is the return value from 477 * the register function. 478 */ 479 480 481 void unregister_sound_special(int unit) 482 { 483 sound_remove_unit(&chains[unit % SOUND_STEP], unit); 484 } 485 486 EXPORT_SYMBOL(unregister_sound_special); 487 488 /** 489 * unregister_sound_mixer - unregister a mixer 490 * @unit: unit number to allocate 491 * 492 * Release a sound device that was allocated with register_sound_mixer(). 493 * The unit passed is the return value from the register function. 494 */ 495 496 void unregister_sound_mixer(int unit) 497 { 498 sound_remove_unit(&chains[0], unit); 499 } 500 501 EXPORT_SYMBOL(unregister_sound_mixer); 502 503 /** 504 * unregister_sound_dsp - unregister a DSP device 505 * @unit: unit number to allocate 506 * 507 * Release a sound device that was allocated with register_sound_dsp(). 508 * The unit passed is the return value from the register function. 509 * 510 * Both of the allocated units are released together automatically. 511 */ 512 513 void unregister_sound_dsp(int unit) 514 { 515 sound_remove_unit(&chains[3], unit); 516 } 517 518 519 EXPORT_SYMBOL(unregister_sound_dsp); 520 521 static struct sound_unit *__look_for_unit(int chain, int unit) 522 { 523 struct sound_unit *s; 524 525 s=chains[chain]; 526 while(s && s->unit_minor <= unit) 527 { 528 if(s->unit_minor==unit) 529 return s; 530 s=s->next; 531 } 532 return NULL; 533 } 534 535 static int soundcore_open(struct inode *inode, struct file *file) 536 { 537 int chain; 538 int unit = iminor(inode); 539 struct sound_unit *s; 540 const struct file_operations *new_fops = NULL; 541 542 chain=unit&0x0F; 543 if(chain==4 || chain==5) /* dsp/audio/dsp16 */ 544 { 545 unit&=0xF0; 546 unit|=3; 547 chain=3; 548 } 549 550 spin_lock(&sound_loader_lock); 551 s = __look_for_unit(chain, unit); 552 if (s) 553 new_fops = fops_get(s->unit_fops); 554 if (preclaim_oss && !new_fops) { 555 spin_unlock(&sound_loader_lock); 556 557 /* 558 * Please, don't change this order or code. 559 * For ALSA slot means soundcard and OSS emulation code 560 * comes as add-on modules which aren't depend on 561 * ALSA toplevel modules for soundcards, thus we need 562 * load them at first. [Jaroslav Kysela <perex@jcu.cz>] 563 */ 564 request_module("sound-slot-%i", unit>>4); 565 request_module("sound-service-%i-%i", unit>>4, chain); 566 567 /* 568 * sound-slot/service-* module aliases are scheduled 569 * for removal in favor of the standard char-major-* 570 * module aliases. For the time being, generate both 571 * the legacy and standard module aliases to ease 572 * transition. 573 */ 574 if (request_module("char-major-%d-%d", SOUND_MAJOR, unit) > 0) 575 request_module("char-major-%d", SOUND_MAJOR); 576 577 spin_lock(&sound_loader_lock); 578 s = __look_for_unit(chain, unit); 579 if (s) 580 new_fops = fops_get(s->unit_fops); 581 } 582 spin_unlock(&sound_loader_lock); 583 if (new_fops) { 584 /* 585 * We rely upon the fact that we can't be unloaded while the 586 * subdriver is there. 587 */ 588 int err = 0; 589 replace_fops(file, new_fops); 590 591 if (file->f_op->open) 592 err = file->f_op->open(inode,file); 593 594 return err; 595 } 596 return -ENODEV; 597 } 598 599 MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR); 600 601 static void cleanup_oss_soundcore(void) 602 { 603 /* We have nothing to really do here - we know the lists must be 604 empty */ 605 unregister_chrdev(SOUND_MAJOR, "sound"); 606 } 607 608 static int __init init_oss_soundcore(void) 609 { 610 if (preclaim_oss && 611 register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) < 0) { 612 printk(KERN_ERR "soundcore: sound device already in use.\n"); 613 return -EBUSY; 614 } 615 616 return 0; 617 } 618 619 #endif /* CONFIG_SOUND_OSS_CORE */ 620