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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Sound core. This file is composed of two parts. sound_class4 * which is common to both OSS and ALSA and OSS sound core which5 * 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_CORE19static int __init init_oss_soundcore(void);20static void cleanup_oss_soundcore(void);21#else22static inline int init_oss_soundcore(void) { return 0; }23static inline void cleanup_oss_soundcore(void) { }24#endif25 26MODULE_DESCRIPTION("Core sound module");27MODULE_AUTHOR("Alan Cox");28MODULE_LICENSE("GPL");29 30static char *sound_devnode(const struct device *dev, umode_t *mode)31{32 if (MAJOR(dev->devt) == SOUND_MAJOR)33 return NULL;34 return kasprintf(GFP_KERNEL, "snd/%s", dev_name(dev));35}36 37const struct class sound_class = {38 .name = "sound",39 .devnode = sound_devnode,40};41EXPORT_SYMBOL(sound_class);42 43static int __init init_soundcore(void)44{45 int rc;46 47 rc = init_oss_soundcore();48 if (rc)49 return rc;50 51 rc = class_register(&sound_class);52 if (rc) {53 cleanup_oss_soundcore();54 return rc;55 }56 57 return 0;58}59 60static void __exit cleanup_soundcore(void)61{62 cleanup_oss_soundcore();63 class_unregister(&sound_class);64}65 66subsys_initcall(init_soundcore);67module_exit(cleanup_soundcore);68 69 70#ifdef CONFIG_SOUND_OSS_CORE71/*72 * OSS sound core handling. Breaks out sound functions to submodules73 * 74 * Author: Alan Cox <alan@lxorguk.ukuu.org.uk>75 *76 * Fixes:77 *78 * --------------------79 * 80 * Top level handler for the sound subsystem. Various devices can81 * plug into this. The fact they don't all go via OSS doesn't mean 82 * they don't have to implement the OSS API. There is a lot of logic83 * to keeping much of the OSS weight out of the code in a compatibility84 * module, but it's up to the driver to rember to load it...85 *86 * The code provides a set of functions for registration of devices87 * by type. This is done rather than providing a single call so that88 * we can hide any future changes in the internals (eg when we go to89 * 32bit dev_t) from the modules and their interface.90 *91 * Secondly we need to allocate the dsp, dsp16 and audio devices as92 * one. Thus we misuse the chains a bit to simplify this.93 *94 * Thirdly to make it more fun and for 2.3.x and above we do all95 * of this using fine grained locking.96 *97 * FIXME: we have to resolve modules and fine grained load/unload98 * locking at some point in 2.3.x.99 */100 101#include <linux/init.h>102#include <linux/slab.h>103#include <linux/types.h>104#include <linux/kernel.h>105#include <linux/sound.h>106#include <linux/kmod.h>107 108#define SOUND_STEP 16109 110struct sound_unit111{112 int unit_minor;113 const struct file_operations *unit_fops;114 struct sound_unit *next;115 char name[32];116};117 118/*119 * By default, OSS sound_core claims full legacy minor range (0-255)120 * of SOUND_MAJOR to trap open attempts to any sound minor and121 * requests modules using custom sound-slot/service-* module aliases.122 * The only benefit of doing this is allowing use of custom module123 * aliases instead of the standard char-major-* ones. This behavior124 * prevents alternative OSS implementation and is scheduled to be125 * removed.126 *127 * CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss kernel128 * parameter are added to allow distros and developers to try and129 * switch to alternative implementations without needing to rebuild130 * the kernel in the meantime. If preclaim_oss is non-zero, the131 * kernel will behave the same as before. All SOUND_MAJOR minors are132 * preclaimed and the custom module aliases along with standard chrdev133 * ones are emitted if a missing device is opened. If preclaim_oss is134 * zero, sound_core only grabs what's actually in use and for missing135 * devices only the standard chrdev aliases are requested.136 *137 * All these clutters are scheduled to be removed along with138 * sound-slot/service-* module aliases.139 */140static int preclaim_oss = IS_ENABLED(CONFIG_SOUND_OSS_CORE_PRECLAIM);141 142module_param(preclaim_oss, int, 0444);143 144static int soundcore_open(struct inode *, struct file *);145 146static const struct file_operations soundcore_fops =147{148 /* We must have an owner or the module locking fails */149 .owner = THIS_MODULE,150 .open = soundcore_open,151 .llseek = noop_llseek,152};153 154/*155 * Low level list operator. Scan the ordered list, find a hole and156 * join into it. Called with the lock asserted157 */158 159static int __sound_insert_unit(struct sound_unit * s, struct sound_unit **list, const struct file_operations *fops, int index, int low, int top)160{161 int n=low;162 163 if (index < 0) { /* first free */164 165 while (*list && (*list)->unit_minor<n)166 list=&((*list)->next);167 168 while(n<top)169 {170 /* Found a hole ? */171 if(*list==NULL || (*list)->unit_minor>n)172 break;173 list=&((*list)->next);174 n+=SOUND_STEP;175 }176 177 if(n>=top)178 return -ENOENT;179 } else {180 n = low+(index*16);181 while (*list) {182 if ((*list)->unit_minor==n)183 return -EBUSY;184 if ((*list)->unit_minor>n)185 break;186 list=&((*list)->next);187 }188 } 189 190 /*191 * Fill it in192 */193 194 s->unit_minor=n;195 s->unit_fops=fops;196 197 /*198 * Link it199 */200 201 s->next=*list;202 *list=s;203 204 205 return n;206}207 208/*209 * Remove a node from the chain. Called with the lock asserted210 */211 212static struct sound_unit *__sound_remove_unit(struct sound_unit **list, int unit)213{214 while(*list)215 {216 struct sound_unit *p=*list;217 if(p->unit_minor==unit)218 {219 *list=p->next;220 return p;221 }222 list=&(p->next);223 }224 printk(KERN_ERR "Sound device %d went missing!\n", unit);225 return NULL;226}227 228/*229 * This lock guards the sound loader list.230 */231 232static DEFINE_SPINLOCK(sound_loader_lock);233 234/*235 * Allocate the controlling structure and add it to the sound driver236 * list. Acquires locks as needed237 */238 239static 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)240{241 struct sound_unit *s = kmalloc(sizeof(*s), GFP_KERNEL);242 int r;243 244 if (!s)245 return -ENOMEM;246 247 spin_lock(&sound_loader_lock);248retry:249 r = __sound_insert_unit(s, list, fops, index, low, top);250 spin_unlock(&sound_loader_lock);251 252 if (r < 0)253 goto fail;254 else if (r < SOUND_STEP)255 sprintf(s->name, "sound/%s", name);256 else257 sprintf(s->name, "sound/%s%d", name, r / SOUND_STEP);258 259 if (!preclaim_oss) {260 /*261 * Something else might have grabbed the minor. If262 * first free slot is requested, rescan with @low set263 * to the next unit; otherwise, -EBUSY.264 */265 r = __register_chrdev(SOUND_MAJOR, s->unit_minor, 1, s->name,266 &soundcore_fops);267 if (r < 0) {268 spin_lock(&sound_loader_lock);269 __sound_remove_unit(list, s->unit_minor);270 if (index < 0) {271 low = s->unit_minor + SOUND_STEP;272 goto retry;273 }274 spin_unlock(&sound_loader_lock);275 r = -EBUSY;276 goto fail;277 }278 }279 280 device_create(&sound_class, dev, MKDEV(SOUND_MAJOR, s->unit_minor),281 NULL, "%s", s->name+6);282 return s->unit_minor;283 284fail:285 kfree(s);286 return r;287}288 289/*290 * Remove a unit. Acquires locks as needed. The drivers MUST have291 * completed the removal before their file operations become292 * invalid.293 */294 295static void sound_remove_unit(struct sound_unit **list, int unit)296{297 struct sound_unit *p;298 299 spin_lock(&sound_loader_lock);300 p = __sound_remove_unit(list, unit);301 spin_unlock(&sound_loader_lock);302 if (p) {303 if (!preclaim_oss)304 __unregister_chrdev(SOUND_MAJOR, p->unit_minor, 1,305 p->name);306 device_destroy(&sound_class, MKDEV(SOUND_MAJOR, p->unit_minor));307 kfree(p);308 }309}310 311/*312 * Allocations313 *314 * 0 *16 Mixers315 * 1 *8 Sequencers316 * 2 *16 Midi317 * 3 *16 DSP318 * 4 *16 SunDSP319 * 5 *16 DSP16320 * 6 -- sndstat (obsolete)321 * 7 *16 unused322 * 8 -- alternate sequencer (see above)323 * 9 *16 raw synthesizer access324 * 10 *16 unused325 * 11 *16 unused326 * 12 *16 unused327 * 13 *16 unused328 * 14 *16 unused329 * 15 *16 unused330 */331 332static struct sound_unit *chains[SOUND_STEP];333 334/**335 * register_sound_special_device - register a special sound node336 * @fops: File operations for the driver337 * @unit: Unit number to allocate338 * @dev: device pointer339 *340 * Allocate a special sound device by minor number from the sound341 * subsystem.342 *343 * Return: The allocated number is returned on success. On failure,344 * a negative error code is returned.345 */346 347int register_sound_special_device(const struct file_operations *fops, int unit,348 struct device *dev)349{350 const int chain = unit % SOUND_STEP;351 int max_unit = 256;352 const char *name;353 char _name[16];354 355 switch (chain) {356 case 0:357 name = "mixer";358 break;359 case 1:360 name = "sequencer";361 if (unit >= SOUND_STEP)362 goto __unknown;363 max_unit = unit + 1;364 break;365 case 2:366 name = "midi";367 break;368 case 3:369 name = "dsp";370 break;371 case 4:372 name = "audio";373 break;374 case 5:375 name = "dspW";376 break;377 case 8:378 name = "sequencer2";379 if (unit >= SOUND_STEP)380 goto __unknown;381 max_unit = unit + 1;382 break;383 case 9:384 name = "dmmidi";385 break;386 case 10:387 name = "dmfm";388 break;389 case 12:390 name = "adsp";391 break;392 case 13:393 name = "amidi";394 break;395 case 14:396 name = "admmidi";397 break;398 default:399 {400 __unknown:401 sprintf(_name, "unknown%d", chain);402 if (unit >= SOUND_STEP)403 strcat(_name, "-");404 name = _name;405 }406 break;407 }408 return sound_insert_unit(&chains[chain], fops, -1, unit, max_unit,409 name, 0600, dev);410}411 412EXPORT_SYMBOL(register_sound_special_device);413 414int register_sound_special(const struct file_operations *fops, int unit)415{416 return register_sound_special_device(fops, unit, NULL);417}418 419EXPORT_SYMBOL(register_sound_special);420 421/**422 * register_sound_mixer - register a mixer device423 * @fops: File operations for the driver424 * @dev: Unit number to allocate425 *426 * Allocate a mixer device. Unit is the number of the mixer requested.427 * Pass -1 to request the next free mixer unit.428 *429 * Return: On success, the allocated number is returned. On failure,430 * a negative error code is returned.431 */432 433int register_sound_mixer(const struct file_operations *fops, int dev)434{435 return sound_insert_unit(&chains[0], fops, dev, 0, 128,436 "mixer", 0600, NULL);437}438 439EXPORT_SYMBOL(register_sound_mixer);440 441/*442 * DSP's are registered as a triple. Register only one and cheat443 * in open - see below.444 */445 446/**447 * register_sound_dsp - register a DSP device448 * @fops: File operations for the driver449 * @dev: Unit number to allocate450 *451 * Allocate a DSP device. Unit is the number of the DSP requested.452 * Pass -1 to request the next free DSP unit.453 *454 * This function allocates both the audio and dsp device entries together455 * and will always allocate them as a matching pair - eg dsp3/audio3456 *457 * Return: On success, the allocated number is returned. On failure,458 * a negative error code is returned.459 */460 461int register_sound_dsp(const struct file_operations *fops, int dev)462{463 return sound_insert_unit(&chains[3], fops, dev, 3, 131,464 "dsp", 0600, NULL);465}466 467EXPORT_SYMBOL(register_sound_dsp);468 469/**470 * unregister_sound_special - unregister a special sound device471 * @unit: unit number to allocate472 *473 * Release a sound device that was allocated with474 * register_sound_special(). The unit passed is the return value from475 * the register function.476 */477 478 479void unregister_sound_special(int unit)480{481 sound_remove_unit(&chains[unit % SOUND_STEP], unit);482}483 484EXPORT_SYMBOL(unregister_sound_special);485 486/**487 * unregister_sound_mixer - unregister a mixer488 * @unit: unit number to allocate489 *490 * Release a sound device that was allocated with register_sound_mixer().491 * The unit passed is the return value from the register function.492 */493 494void unregister_sound_mixer(int unit)495{496 sound_remove_unit(&chains[0], unit);497}498 499EXPORT_SYMBOL(unregister_sound_mixer);500 501/**502 * unregister_sound_dsp - unregister a DSP device503 * @unit: unit number to allocate504 *505 * Release a sound device that was allocated with register_sound_dsp().506 * The unit passed is the return value from the register function.507 *508 * Both of the allocated units are released together automatically.509 */510 511void unregister_sound_dsp(int unit)512{513 sound_remove_unit(&chains[3], unit);514}515 516 517EXPORT_SYMBOL(unregister_sound_dsp);518 519static struct sound_unit *__look_for_unit(int chain, int unit)520{521 struct sound_unit *s;522 523 s=chains[chain];524 while(s && s->unit_minor <= unit)525 {526 if(s->unit_minor==unit)527 return s;528 s=s->next;529 }530 return NULL;531}532 533static int soundcore_open(struct inode *inode, struct file *file)534{535 int chain;536 int unit = iminor(inode);537 struct sound_unit *s;538 const struct file_operations *new_fops = NULL;539 540 chain=unit&0x0F;541 if(chain==4 || chain==5) /* dsp/audio/dsp16 */542 {543 unit&=0xF0;544 unit|=3;545 chain=3;546 }547 548 spin_lock(&sound_loader_lock);549 s = __look_for_unit(chain, unit);550 if (s)551 new_fops = fops_get(s->unit_fops);552 if (preclaim_oss && !new_fops) {553 spin_unlock(&sound_loader_lock);554 555 /*556 * Please, don't change this order or code.557 * For ALSA slot means soundcard and OSS emulation code558 * comes as add-on modules which aren't depend on559 * ALSA toplevel modules for soundcards, thus we need560 * load them at first. [Jaroslav Kysela <perex@jcu.cz>]561 */562 request_module("sound-slot-%i", unit>>4);563 request_module("sound-service-%i-%i", unit>>4, chain);564 565 /*566 * sound-slot/service-* module aliases are scheduled567 * for removal in favor of the standard char-major-*568 * module aliases. For the time being, generate both569 * the legacy and standard module aliases to ease570 * transition.571 */572 if (request_module("char-major-%d-%d", SOUND_MAJOR, unit) > 0)573 request_module("char-major-%d", SOUND_MAJOR);574 575 spin_lock(&sound_loader_lock);576 s = __look_for_unit(chain, unit);577 if (s)578 new_fops = fops_get(s->unit_fops);579 }580 spin_unlock(&sound_loader_lock);581 582 if (!new_fops)583 return -ENODEV;584 585 /*586 * We rely upon the fact that we can't be unloaded while the587 * subdriver is there.588 */589 replace_fops(file, new_fops);590 591 if (!file->f_op->open)592 return -ENODEV;593 594 return file->f_op->open(inode, file);595}596 597MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);598 599static void cleanup_oss_soundcore(void)600{601 /* We have nothing to really do here - we know the lists must be602 empty */603 unregister_chrdev(SOUND_MAJOR, "sound");604}605 606static int __init init_oss_soundcore(void)607{608 if (preclaim_oss &&609 register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) < 0) {610 printk(KERN_ERR "soundcore: sound device already in use.\n");611 return -EBUSY;612 }613 614 return 0;615}616 617#endif /* CONFIG_SOUND_OSS_CORE */618