sound/core/init.c

   1 /*
   2  *  Initialization routines
   3  *  Copyright (c) by Jaroslav Kysela <perex@suse.cz>
   4  *
   5  *
   6  *   This program is free software; you can redistribute it and/or modify
   7  *   it under the terms of the GNU General Public License as published by
   8  *   the Free Software Foundation; either version 2 of the License, or
   9  *   (at your option) any later version.
  10  *
  11  *   This program is distributed in the hope that it will be useful,
  12  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *   GNU General Public License for more details.
  15  *
  16  *   You should have received a copy of the GNU General Public License
  17  *   along with this program; if not, write to the Free Software
  18  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  19  *
  20  */
  21
  22 #include <sound/driver.h>
  23 #include <linux/init.h>
  24 #include <linux/sched.h>
  25 #include <linux/file.h>
  26 #include <linux/slab.h>
  27 #include <linux/time.h>
  28 #include <linux/ctype.h>
  29 #include <linux/pci.h>
  30 #include <linux/pm.h>
  31
  32 #include <sound/core.h>
  33 #include <sound/control.h>
  34 #include <sound/info.h>
  35
  36 static DEFINE_SPINLOCK(shutdown_lock);
  37 static LIST_HEAD(shutdown_files);
  38
  39 static struct file_operations snd_shutdown_f_ops;
  40
  41 static unsigned int snd_cards_lock;     /* locked for registering/using */
  42 struct snd_card *snd_cards[SNDRV_CARDS];
  43 EXPORT_SYMBOL(snd_cards);
  44
  45 static DEFINE_MUTEX(snd_card_mutex);
  46
  47 #if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
  48 int (*snd_mixer_oss_notify_callback)(struct snd_card *card, int free_flag);
  49 EXPORT_SYMBOL(snd_mixer_oss_notify_callback);
  50 #endif
  51
  52 #ifdef CONFIG_PROC_FS
  53 static void snd_card_id_read(struct snd_info_entry *entry,
  54                              struct snd_info_buffer *buffer)
  55 {
  56         snd_iprintf(buffer, "%s\n", entry->card->id);
  57 }
  58
  59 static inline int init_info_for_card(struct snd_card *card)
  60 {
  61         int err;
  62         struct snd_info_entry *entry;
  63
  64         if ((err = snd_info_card_register(card)) < 0) {
  65                 snd_printd("unable to create card info\n");
  66                 return err;
  67         }
  68         if ((entry = snd_info_create_card_entry(card, "id", card->proc_root)) == NULL) {
  69                 snd_printd("unable to create card entry\n");
  70                 return err;
  71         }
  72         entry->c.text.read = snd_card_id_read;
  73         if (snd_info_register(entry) < 0) {
  74                 snd_info_free_entry(entry);
  75                 entry = NULL;
  76         }
  77         card->proc_id = entry;
  78         return 0;
  79 }
  80 #else /* !CONFIG_PROC_FS */
  81 #define init_info_for_card(card)
  82 #endif
  83
  84 /**
  85  *  snd_card_new - create and initialize a soundcard structure
  86  *  @idx: card index (address) [0 ... (SNDRV_CARDS-1)]
  87  *  @xid: card identification (ASCII string)
  88  *  @module: top level module for locking
  89  *  @extra_size: allocate this extra size after the main soundcard structure
  90  *
  91  *  Creates and initializes a soundcard structure.
  92  *
  93  *  Returns kmallocated snd_card structure. Creates the ALSA control interface
  94  *  (which is blocked until snd_card_register function is called).
  95  */
  96 struct snd_card *snd_card_new(int idx, const char *xid,
  97                          struct module *module, int extra_size)
  98 {
  99         struct snd_card *card;
 100         int err;
 101
 102         if (extra_size < 0)
 103                 extra_size = 0;
 104         card = kzalloc(sizeof(*card) + extra_size, GFP_KERNEL);
 105         if (card == NULL)
 106                 return NULL;
 107         if (xid) {
 108                 if (!snd_info_check_reserved_words(xid))
 109                         goto __error;
 110                 strlcpy(card->id, xid, sizeof(card->id));
 111         }
 112         err = 0;
 113         mutex_lock(&snd_card_mutex);
 114         if (idx < 0) {
 115                 int idx2;
 116                 for (idx2 = 0; idx2 < SNDRV_CARDS; idx2++)
 117                         if (~snd_cards_lock & idx & 1<<idx2) {
 118                                 idx = idx2;
 119                                 if (idx >= snd_ecards_limit)
 120                                         snd_ecards_limit = idx + 1;
 121                                 break;
 122                         }
 123         } else if (idx < snd_ecards_limit) {
 124                 if (snd_cards_lock & (1 << idx))
 125                         err = -ENODEV;  /* invalid */
 126         } else if (idx < SNDRV_CARDS)
 127                 snd_ecards_limit = idx + 1; /* increase the limit */
 128         else
 129                 err = -ENODEV;
 130         if (idx < 0 || err < 0) {
 131                 mutex_unlock(&snd_card_mutex);
 132                 snd_printk(KERN_ERR "cannot find the slot for index %d (range 0-%i)\n", idx, snd_ecards_limit - 1);
 133                 goto __error;
 134         }
 135         snd_cards_lock |= 1 << idx;             /* lock it */
 136         mutex_unlock(&snd_card_mutex);
 137         card->number = idx;
 138         card->module = module;
 139         INIT_LIST_HEAD(&card->devices);
 140         init_rwsem(&card->controls_rwsem);
 141         rwlock_init(&card->ctl_files_rwlock);
 142         INIT_LIST_HEAD(&card->controls);
 143         INIT_LIST_HEAD(&card->ctl_files);
 144         spin_lock_init(&card->files_lock);
 145         init_waitqueue_head(&card->shutdown_sleep);
 146 #ifdef CONFIG_PM
 147         mutex_init(&card->power_lock);
 148         init_waitqueue_head(&card->power_sleep);
 149 #endif
 150         /* the control interface cannot be accessed from the user space until */
 151         /* snd_cards_bitmask and snd_cards are set with snd_card_register */
 152         if ((err = snd_ctl_create(card)) < 0) {
 153                 snd_printd("unable to register control minors\n");
 154                 goto __error;
 155         }
 156         if ((err = snd_info_card_create(card)) < 0) {
 157                 snd_printd("unable to create card info\n");
 158                 goto __error_ctl;
 159         }
 160         if (extra_size > 0)
 161                 card->private_data = (char *)card + sizeof(struct snd_card);
 162         return card;
 163
 164       __error_ctl:
 165         snd_device_free_all(card, SNDRV_DEV_CMD_PRE);
 166       __error:
 167         kfree(card);
 168         return NULL;
 169 }
 170
 171 EXPORT_SYMBOL(snd_card_new);
 172
 173 /* return non-zero if a card is already locked */
 174 int snd_card_locked(int card)
 175 {
 176         int locked;
 177
 178         mutex_lock(&snd_card_mutex);
 179         locked = snd_cards_lock & (1 << card);
 180         mutex_unlock(&snd_card_mutex);
 181         return locked;
 182 }
 183
 184 static loff_t snd_disconnect_llseek(struct file *file, loff_t offset, int orig)
 185 {
 186         return -ENODEV;
 187 }
 188
 189 static ssize_t snd_disconnect_read(struct file *file, char __user *buf,
 190                                    size_t count, loff_t *offset)
 191 {
 192         return -ENODEV;
 193 }
 194
 195 static ssize_t snd_disconnect_write(struct file *file, const char __user *buf,
 196                                     size_t count, loff_t *offset)
 197 {
 198         return -ENODEV;
 199 }
 200
 201 static int snd_disconnect_release(struct inode *inode, struct file *file)
 202 {
 203         struct snd_monitor_file *df = NULL, *_df;
 204
 205         spin_lock(&shutdown_lock);
 206         list_for_each_entry(_df, &shutdown_files, shutdown_list) {
 207                 if (_df->file == file) {
 208                         df = _df;
 209                         break;
 210                 }
 211         }
 212         spin_unlock(&shutdown_lock);
 213
 214         if (likely(df))
 215                 return df->disconnected_f_op->release(inode, file);
 216
 217         panic("%s(%p, %p) failed!", __FUNCTION__, inode, file);
 218 }
 219
 220 static unsigned int snd_disconnect_poll(struct file * file, poll_table * wait)
 221 {
 222         return POLLERR | POLLNVAL;
 223 }
 224
 225 static long snd_disconnect_ioctl(struct file *file,
 226                                  unsigned int cmd, unsigned long arg)
 227 {
 228         return -ENODEV;
 229 }
 230
 231 static int snd_disconnect_mmap(struct file *file, struct vm_area_struct *vma)
 232 {
 233         return -ENODEV;
 234 }
 235
 236 static int snd_disconnect_fasync(int fd, struct file *file, int on)
 237 {
 238         return -ENODEV;
 239 }
 240
 241 static struct file_operations snd_shutdown_f_ops =
 242 {
 243         .owner =        THIS_MODULE,
 244         .llseek =       snd_disconnect_llseek,
 245         .read =         snd_disconnect_read,
 246         .write =        snd_disconnect_write,
 247         .release =      snd_disconnect_release,
 248         .poll =         snd_disconnect_poll,
 249         .unlocked_ioctl = snd_disconnect_ioctl,
 250 #ifdef CONFIG_COMPAT
 251         .compat_ioctl = snd_disconnect_ioctl,
 252 #endif
 253         .mmap =         snd_disconnect_mmap,
 254         .fasync =       snd_disconnect_fasync
 255 };
 256
 257 /**
 258  *  snd_card_disconnect - disconnect all APIs from the file-operations (user space)
 259  *  @card: soundcard structure
 260  *
 261  *  Disconnects all APIs from the file-operations (user space).
 262  *
 263  *  Returns zero, otherwise a negative error code.
 264  *
 265  *  Note: The current implementation replaces all active file->f_op with special
 266  *        dummy file operations (they do nothing except release).
 267  */
 268 int snd_card_disconnect(struct snd_card *card)
 269 {
 270         struct snd_monitor_file *mfile;
 271         struct file *file;
 272         int err;
 273
 274         spin_lock(&card->files_lock);
 275         if (card->shutdown) {
 276                 spin_unlock(&card->files_lock);
 277                 return 0;
 278         }
 279         card->shutdown = 1;
 280         spin_unlock(&card->files_lock);
 281
 282         /* phase 1: disable fops (user space) operations for ALSA API */
 283         mutex_lock(&snd_card_mutex);
 284         snd_cards[card->number] = NULL;
 285         mutex_unlock(&snd_card_mutex);
 286
 287         /* phase 2: replace file->f_op with special dummy operations */
 288
 289         spin_lock(&card->files_lock);
 290         mfile = card->files;
 291         while (mfile) {
 292                 file = mfile->file;
 293
 294                 /* it's critical part, use endless loop */
 295                 /* we have no room to fail */
 296                 mfile->disconnected_f_op = mfile->file->f_op;
 297
 298                 spin_lock(&shutdown_lock);
 299                 list_add(&mfile->shutdown_list, &shutdown_files);
 300                 spin_unlock(&shutdown_lock);
 301
 302                 fops_get(&snd_shutdown_f_ops);
 303                 mfile->file->f_op = &snd_shutdown_f_ops;
 304
 305                 mfile = mfile->next;
 306         }
 307         spin_unlock(&card->files_lock);
 308
 309         /* phase 3: notify all connected devices about disconnection */
 310         /* at this point, they cannot respond to any calls except release() */
 311
 312 #if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
 313         if (snd_mixer_oss_notify_callback)
 314                 snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_DISCONNECT);
 315 #endif
 316
 317         /* notify all devices that we are disconnected */
 318         err = snd_device_disconnect_all(card);
 319         if (err < 0)
 320                 snd_printk(KERN_ERR "not all devices for card %i can be disconnected\n", card->number);
 321
 322         snd_info_card_disconnect(card);
 323         return 0;
 324 }
 325
 326 EXPORT_SYMBOL(snd_card_disconnect);
 327
 328 /**
 329  *  snd_card_free - frees given soundcard structure
 330  *  @card: soundcard structure
 331  *
 332  *  This function releases the soundcard structure and the all assigned
 333  *  devices automatically.  That is, you don't have to release the devices
 334  *  by yourself.
 335  *
 336  *  Returns zero. Frees all associated devices and frees the control
 337  *  interface associated to given soundcard.
 338  */
 339 static int snd_card_do_free(struct snd_card *card)
 340 {
 341 #if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
 342         if (snd_mixer_oss_notify_callback)
 343                 snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_FREE);
 344 #endif
 345         if (snd_device_free_all(card, SNDRV_DEV_CMD_PRE) < 0) {
 346                 snd_printk(KERN_ERR "unable to free all devices (pre)\n");
 347                 /* Fatal, but this situation should never occur */
 348         }
 349         if (snd_device_free_all(card, SNDRV_DEV_CMD_NORMAL) < 0) {
 350                 snd_printk(KERN_ERR "unable to free all devices (normal)\n");
 351                 /* Fatal, but this situation should never occur */
 352         }
 353         if (snd_device_free_all(card, SNDRV_DEV_CMD_POST) < 0) {
 354                 snd_printk(KERN_ERR "unable to free all devices (post)\n");
 355                 /* Fatal, but this situation should never occur */
 356         }
 357         if (card->private_free)
 358                 card->private_free(card);
 359         snd_info_free_entry(card->proc_id);
 360         if (snd_info_card_free(card) < 0) {
 361                 snd_printk(KERN_WARNING "unable to free card info\n");
 362                 /* Not fatal error */
 363         }
 364 #ifndef CONFIG_SYSFS_DEPRECATED
 365         if (card->card_dev)
 366                 device_unregister(card->card_dev);
 367 #endif
 368         kfree(card);
 369         return 0;
 370 }
 371
 372 static int snd_card_free_prepare(struct snd_card *card)
 373 {
 374         if (card == NULL)
 375                 return -EINVAL;
 376         (void) snd_card_disconnect(card);
 377         mutex_lock(&snd_card_mutex);
 378         snd_cards[card->number] = NULL;
 379         snd_cards_lock &= ~(1 << card->number);
 380         mutex_unlock(&snd_card_mutex);
 381 #ifdef CONFIG_PM
 382         wake_up(&card->power_sleep);
 383 #endif
 384         return 0;
 385 }
 386
 387 int snd_card_free_when_closed(struct snd_card *card)
 388 {
 389         int free_now = 0;
 390         int ret = snd_card_free_prepare(card);
 391         if (ret)
 392                 return ret;
 393
 394         spin_lock(&card->files_lock);
 395         if (card->files == NULL)
 396                 free_now = 1;
 397         else
 398                 card->free_on_last_close = 1;
 399         spin_unlock(&card->files_lock);
 400
 401         if (free_now)
 402                 snd_card_do_free(card);
 403         return 0;
 404 }
 405
 406 EXPORT_SYMBOL(snd_card_free_when_closed);
 407
 408 int snd_card_free(struct snd_card *card)
 409 {
 410         int ret = snd_card_free_prepare(card);
 411         if (ret)
 412                 return ret;
 413
 414         /* wait, until all devices are ready for the free operation */
 415         wait_event(card->shutdown_sleep, card->files == NULL);
 416         snd_card_do_free(card);
 417         return 0;
 418 }
 419
 420 EXPORT_SYMBOL(snd_card_free);
 421
 422 static void choose_default_id(struct snd_card *card)
 423 {
 424         int i, len, idx_flag = 0, loops = SNDRV_CARDS;
 425         char *id, *spos;
 426
 427         id = spos = card->shortname;
 428         while (*id != '\0') {
 429                 if (*id == ' ')
 430                         spos = id + 1;
 431                 id++;
 432         }
 433         id = card->id;
 434         while (*spos != '\0' && !isalnum(*spos))
 435                 spos++;
 436         if (isdigit(*spos))
 437                 *id++ = isalpha(card->shortname[0]) ? card->shortname[0] : 'D';
 438         while (*spos != '\0' && (size_t)(id - card->id) < sizeof(card->id) - 1) {
 439                 if (isalnum(*spos))
 440                         *id++ = *spos;
 441                 spos++;
 442         }
 443         *id = '\0';
 444
 445         id = card->id;
 446
 447         if (*id == '\0')
 448                 strcpy(id, "default");
 449
 450         while (1) {
 451                 if (loops-- == 0) {
 452                         snd_printk(KERN_ERR "unable to choose default card id (%s)\n", id);
 453                         strcpy(card->id, card->proc_root->name);
 454                         return;
 455                 }
 456                 if (!snd_info_check_reserved_words(id))
 457                         goto __change;
 458                 for (i = 0; i < snd_ecards_limit; i++) {
 459                         if (snd_cards[i] && !strcmp(snd_cards[i]->id, id))
 460                                 goto __change;
 461                 }
 462                 break;
 463
 464               __change:
 465                 len = strlen(id);
 466                 if (idx_flag) {
 467                         if (id[len-1] != '9')
 468                                 id[len-1]++;
 469                         else
 470                                 id[len-1] = 'A';
 471                 } else if ((size_t)len <= sizeof(card->id) - 3) {
 472                         strcat(id, "_1");
 473                         idx_flag++;
 474                 } else {
 475                         spos = id + len - 2;
 476                         if ((size_t)len <= sizeof(card->id) - 2)
 477                                 spos++;
 478                         *spos++ = '_';
 479                         *spos++ = '1';
 480                         *spos++ = '\0';
 481                         idx_flag++;
 482                 }
 483         }
 484 }
 485
 486 /**
 487  *  snd_card_register - register the soundcard
 488  *  @card: soundcard structure
 489  *
 490  *  This function registers all the devices assigned to the soundcard.
 491  *  Until calling this, the ALSA control interface is blocked from the
 492  *  external accesses.  Thus, you should call this function at the end
 493  *  of the initialization of the card.
 494  *
 495  *  Returns zero otherwise a negative error code if the registrain failed.
 496  */
 497 int snd_card_register(struct snd_card *card)
 498 {
 499         int err;
 500
 501         snd_assert(card != NULL, return -EINVAL);
 502 #ifndef CONFIG_SYSFS_DEPRECATED
 503         if (!card->card_dev) {
 504                 card->card_dev = device_create(sound_class, card->dev, 0,
 505                                                "card%i", card->number);
 506                 if (IS_ERR(card->card_dev))
 507                         card->card_dev = NULL;
 508         }
 509 #endif
 510         if ((err = snd_device_register_all(card)) < 0)
 511                 return err;
 512         mutex_lock(&snd_card_mutex);
 513         if (snd_cards[card->number]) {
 514                 /* already registered */
 515                 mutex_unlock(&snd_card_mutex);
 516                 return 0;
 517         }
 518         if (card->id[0] == '\0')
 519                 choose_default_id(card);
 520         snd_cards[card->number] = card;
 521         mutex_unlock(&snd_card_mutex);
 522         init_info_for_card(card);
 523 #if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
 524         if (snd_mixer_oss_notify_callback)
 525                 snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_REGISTER);
 526 #endif
 527         return 0;
 528 }
 529
 530 EXPORT_SYMBOL(snd_card_register);
 531
 532 #ifdef CONFIG_PROC_FS
 533 static struct snd_info_entry *snd_card_info_entry;
 534
 535 static void snd_card_info_read(struct snd_info_entry *entry,
 536                                struct snd_info_buffer *buffer)
 537 {
 538         int idx, count;
 539         struct snd_card *card;
 540
 541         for (idx = count = 0; idx < SNDRV_CARDS; idx++) {
 542                 mutex_lock(&snd_card_mutex);
 543                 if ((card = snd_cards[idx]) != NULL) {
 544                         count++;
 545                         snd_iprintf(buffer, "%2i [%-15s]: %s - %s\n",
 546                                         idx,
 547                                         card->id,
 548                                         card->driver,
 549                                         card->shortname);
 550                         snd_iprintf(buffer, "                      %s\n",
 551                                         card->longname);
 552                 }
 553                 mutex_unlock(&snd_card_mutex);
 554         }
 555         if (!count)
 556                 snd_iprintf(buffer, "--- no soundcards ---\n");
 557 }
 558
 559 #ifdef CONFIG_SND_OSSEMUL
 560
 561 void snd_card_info_read_oss(struct snd_info_buffer *buffer)
 562 {
 563         int idx, count;
 564         struct snd_card *card;
 565
 566         for (idx = count = 0; idx < SNDRV_CARDS; idx++) {
 567                 mutex_lock(&snd_card_mutex);
 568                 if ((card = snd_cards[idx]) != NULL) {
 569                         count++;
 570                         snd_iprintf(buffer, "%s\n", card->longname);
 571                 }
 572                 mutex_unlock(&snd_card_mutex);
 573         }
 574         if (!count) {
 575                 snd_iprintf(buffer, "--- no soundcards ---\n");
 576         }
 577 }
 578
 579 #endif
 580
 581 #ifdef MODULE
 582 static struct snd_info_entry *snd_card_module_info_entry;
 583 static void snd_card_module_info_read(struct snd_info_entry *entry,
 584                                       struct snd_info_buffer *buffer)
 585 {
 586         int idx;
 587         struct snd_card *card;
 588
 589         for (idx = 0; idx < SNDRV_CARDS; idx++) {
 590                 mutex_lock(&snd_card_mutex);
 591                 if ((card = snd_cards[idx]) != NULL)
 592                         snd_iprintf(buffer, "%2i %s\n",
 593                                     idx, card->module->name);
 594                 mutex_unlock(&snd_card_mutex);
 595         }
 596 }
 597 #endif
 598
 599 int __init snd_card_info_init(void)
 600 {
 601         struct snd_info_entry *entry;
 602
 603         entry = snd_info_create_module_entry(THIS_MODULE, "cards", NULL);
 604         if (! entry)
 605                 return -ENOMEM;
 606         entry->c.text.read = snd_card_info_read;
 607         if (snd_info_register(entry) < 0) {
 608                 snd_info_free_entry(entry);
 609                 return -ENOMEM;
 610         }
 611         snd_card_info_entry = entry;
 612
 613 #ifdef MODULE
 614         entry = snd_info_create_module_entry(THIS_MODULE, "modules", NULL);
 615         if (entry) {
 616                 entry->c.text.read = snd_card_module_info_read;
 617                 if (snd_info_register(entry) < 0)
 618                         snd_info_free_entry(entry);
 619                 else
 620                         snd_card_module_info_entry = entry;
 621         }
 622 #endif
 623
 624         return 0;
 625 }
 626
 627 int __exit snd_card_info_done(void)
 628 {
 629         snd_info_free_entry(snd_card_info_entry);
 630 #ifdef MODULE
 631         snd_info_free_entry(snd_card_module_info_entry);
 632 #endif
 633         return 0;
 634 }
 635
 636 #endif /* CONFIG_PROC_FS */
 637
 638 /**
 639  *  snd_component_add - add a component string
 640  *  @card: soundcard structure
 641  *  @component: the component id string
 642  *
 643  *  This function adds the component id string to the supported list.
 644  *  The component can be referred from the alsa-lib.
 645  *
 646  *  Returns zero otherwise a negative error code.
 647  */
 648
 649 int snd_component_add(struct snd_card *card, const char *component)
 650 {
 651         char *ptr;
 652         int len = strlen(component);
 653
 654         ptr = strstr(card->components, component);
 655         if (ptr != NULL) {
 656                 if (ptr[len] == '\0' || ptr[len] == ' ')        /* already there */
 657                         return 1;
 658         }
 659         if (strlen(card->components) + 1 + len + 1 > sizeof(card->components)) {
 660                 snd_BUG();
 661                 return -ENOMEM;
 662         }
 663         if (card->components[0] != '\0')
 664                 strcat(card->components, " ");
 665         strcat(card->components, component);
 666         return 0;
 667 }
 668
 669 EXPORT_SYMBOL(snd_component_add);
 670
 671 /**
 672  *  snd_card_file_add - add the file to the file list of the card
 673  *  @card: soundcard structure
 674  *  @file: file pointer
 675  *
 676  *  This function adds the file to the file linked-list of the card.
 677  *  This linked-list is used to keep tracking the connection state,
 678  *  and to avoid the release of busy resources by hotplug.
 679  *
 680  *  Returns zero or a negative error code.
 681  */
 682 int snd_card_file_add(struct snd_card *card, struct file *file)
 683 {
 684         struct snd_monitor_file *mfile;
 685
 686         mfile = kmalloc(sizeof(*mfile), GFP_KERNEL);
 687         if (mfile == NULL)
 688                 return -ENOMEM;
 689         mfile->file = file;
 690         mfile->disconnected_f_op = NULL;
 691         mfile->next = NULL;
 692         spin_lock(&card->files_lock);
 693         if (card->shutdown) {
 694                 spin_unlock(&card->files_lock);
 695                 kfree(mfile);
 696                 return -ENODEV;
 697         }
 698         mfile->next = card->files;
 699         card->files = mfile;
 700         spin_unlock(&card->files_lock);
 701         return 0;
 702 }
 703
 704 EXPORT_SYMBOL(snd_card_file_add);
 705
 706 /**
 707  *  snd_card_file_remove - remove the file from the file list
 708  *  @card: soundcard structure
 709  *  @file: file pointer
 710  *
 711  *  This function removes the file formerly added to the card via
 712  *  snd_card_file_add() function.
 713  *  If all files are removed and snd_card_free_when_closed() was
 714  *  called beforehand, it processes the pending release of
 715  *  resources.
 716  *
 717  *  Returns zero or a negative error code.
 718  */
 719 int snd_card_file_remove(struct snd_card *card, struct file *file)
 720 {
 721         struct snd_monitor_file *mfile, *pfile = NULL;
 722         int last_close = 0;
 723
 724         spin_lock(&card->files_lock);
 725         mfile = card->files;
 726         while (mfile) {
 727                 if (mfile->file == file) {
 728                         if (pfile)
 729                                 pfile->next = mfile->next;
 730                         else
 731                                 card->files = mfile->next;
 732                         break;
 733                 }
 734                 pfile = mfile;
 735                 mfile = mfile->next;
 736         }
 737         if (mfile && mfile->disconnected_f_op) {
 738                 fops_put(mfile->disconnected_f_op);
 739                 spin_lock(&shutdown_lock);
 740                 list_del(&mfile->shutdown_list);
 741                 spin_unlock(&shutdown_lock);
 742         }
 743         if (card->files == NULL)
 744                 last_close = 1;
 745         spin_unlock(&card->files_lock);
 746         if (last_close) {
 747                 wake_up(&card->shutdown_sleep);
 748                 if (card->free_on_last_close)
 749                         snd_card_do_free(card);
 750         }
 751         if (!mfile) {
 752                 snd_printk(KERN_ERR "ALSA card file remove problem (%p)\n", file);
 753                 return -ENOENT;
 754         }
 755         kfree(mfile);
 756         return 0;
 757 }
 758
 759 EXPORT_SYMBOL(snd_card_file_remove);
 760
 761 #ifdef CONFIG_PM
 762 /**
 763  *  snd_power_wait - wait until the power-state is changed.
 764  *  @card: soundcard structure
 765  *  @power_state: expected power state
 766  *
 767  *  Waits until the power-state is changed.
 768  *
 769  *  Note: the power lock must be active before call.
 770  */
 771 int snd_power_wait(struct snd_card *card, unsigned int power_state)
 772 {
 773         wait_queue_t wait;
 774         int result = 0;
 775
 776         /* fastpath */
 777         if (snd_power_get_state(card) == power_state)
 778                 return 0;
 779         init_waitqueue_entry(&wait, current);
 780         add_wait_queue(&card->power_sleep, &wait);
 781         while (1) {
 782                 if (card->shutdown) {
 783                         result = -ENODEV;
 784                         break;
 785                 }
 786                 if (snd_power_get_state(card) == power_state)
 787                         break;
 788                 set_current_state(TASK_UNINTERRUPTIBLE);
 789                 snd_power_unlock(card);
 790                 schedule_timeout(30 * HZ);
 791                 snd_power_lock(card);
 792         }
 793         remove_wait_queue(&card->power_sleep, &wait);
 794         return result;
 795 }
 796
 797 EXPORT_SYMBOL(snd_power_wait);
 798 #endif /* CONFIG_PM */