sound/usb/card.c

   1 /*
   2  *   (Tentative) USB Audio Driver for ALSA
   3  *
   4  *   Copyright (c) 2002 by Takashi Iwai <tiwai@suse.de>
   5  *
   6  *   Many codes borrowed from audio.c by
   7  *          Alan Cox (alan@lxorguk.ukuu.org.uk)
   8  *          Thomas Sailer (sailer@ife.ee.ethz.ch)
   9  *
  10  *
  11  *   This program is free software; you can redistribute it and/or modify
  12  *   it under the terms of the GNU General Public License as published by
  13  *   the Free Software Foundation; either version 2 of the License, or
  14  *   (at your option) any later version.
  15  *
  16  *   This program is distributed in the hope that it will be useful,
  17  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  *   GNU General Public License for more details.
  20  *
  21  *   You should have received a copy of the GNU General Public License
  22  *   along with this program; if not, write to the Free Software
  23  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  24  *
  25  *
  26  *  NOTES:
  27  *
  28  *   - async unlink should be used for avoiding the sleep inside lock.
  29  *     2.4.22 usb-uhci seems buggy for async unlinking and results in
  30  *     oops.  in such a cse, pass async_unlink=0 option.
  31  *   - the linked URBs would be preferred but not used so far because of
  32  *     the instability of unlinking.
  33  *   - type II is not supported properly.  there is no device which supports
  34  *     this type *correctly*.  SB extigy looks as if it supports, but it's
  35  *     indeed an AC3 stream packed in SPDIF frames (i.e. no real AC3 stream).
  36  */
  37
  38
  39 #include <linux/bitops.h>
  40 #include <linux/init.h>
  41 #include <linux/list.h>
  42 #include <linux/slab.h>
  43 #include <linux/string.h>
  44 #include <linux/usb.h>
  45 #include <linux/moduleparam.h>
  46 #include <linux/mutex.h>
  47 #include <linux/usb/audio.h>
  48 #include <linux/usb/audio-v2.h>
  49
  50 #include <sound/core.h>
  51 #include <sound/info.h>
  52 #include <sound/pcm.h>
  53 #include <sound/pcm_params.h>
  54 #include <sound/initval.h>
  55
  56 #include "usbaudio.h"
  57 #include "card.h"
  58 #include "midi.h"
  59 #include "mixer.h"
  60 #include "proc.h"
  61 #include "quirks.h"
  62 #include "endpoint.h"
  63 #include "helper.h"
  64 #include "debug.h"
  65 #include "pcm.h"
  66 #include "urb.h"
  67 #include "format.h"
  68
  69 MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
  70 MODULE_DESCRIPTION("USB Audio");
  71 MODULE_LICENSE("GPL");
  72 MODULE_SUPPORTED_DEVICE("{{Generic,USB Audio}}");
  73
  74
  75 static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;      /* Index 0-MAX */
  76 static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;       /* ID for this card */
  77 static int enable[SNDRV_CARDS] = SNDRV_DEFAULT_ENABLE_PNP;/* Enable this card */
  78 /* Vendor/product IDs for this card */
  79 static int vid[SNDRV_CARDS] = { [0 ... (SNDRV_CARDS-1)] = -1 };
  80 static int pid[SNDRV_CARDS] = { [0 ... (SNDRV_CARDS-1)] = -1 };
  81 static int nrpacks = 8;         /* max. number of packets per urb */
  82 static int async_unlink = 1;
  83 static int device_setup[SNDRV_CARDS]; /* device parameter for this card */
  84 static int ignore_ctl_error;
  85
  86 module_param_array(index, int, NULL, 0444);
  87 MODULE_PARM_DESC(index, "Index value for the USB audio adapter.");
  88 module_param_array(id, charp, NULL, 0444);
  89 MODULE_PARM_DESC(id, "ID string for the USB audio adapter.");
  90 module_param_array(enable, bool, NULL, 0444);
  91 MODULE_PARM_DESC(enable, "Enable USB audio adapter.");
  92 module_param_array(vid, int, NULL, 0444);
  93 MODULE_PARM_DESC(vid, "Vendor ID for the USB audio device.");
  94 module_param_array(pid, int, NULL, 0444);
  95 MODULE_PARM_DESC(pid, "Product ID for the USB audio device.");
  96 module_param(nrpacks, int, 0644);
  97 MODULE_PARM_DESC(nrpacks, "Max. number of packets per URB.");
  98 module_param(async_unlink, bool, 0444);
  99 MODULE_PARM_DESC(async_unlink, "Use async unlink mode.");
 100 module_param_array(device_setup, int, NULL, 0444);
 101 MODULE_PARM_DESC(device_setup, "Specific device setup (if needed).");
 102 module_param(ignore_ctl_error, bool, 0444);
 103 MODULE_PARM_DESC(ignore_ctl_error,
 104                  "Ignore errors from USB controller for mixer interfaces.");
 105
 106 /*
 107  * we keep the snd_usb_audio_t instances by ourselves for merging
 108  * the all interfaces on the same card as one sound device.
 109  */
 110
 111 static DEFINE_MUTEX(register_mutex);
 112 static struct snd_usb_audio *usb_chip[SNDRV_CARDS];
 113 static struct usb_driver usb_audio_driver;
 114
 115 /*
 116  * disconnect streams
 117  * called from snd_usb_audio_disconnect()
 118  */
 119 static void snd_usb_stream_disconnect(struct list_head *head)
 120 {
 121         int idx;
 122         struct snd_usb_stream *as;
 123         struct snd_usb_substream *subs;
 124
 125         as = list_entry(head, struct snd_usb_stream, list);
 126         for (idx = 0; idx < 2; idx++) {
 127                 subs = &as->substream[idx];
 128                 if (!subs->num_formats)
 129                         continue;
 130                 snd_usb_release_substream_urbs(subs, 1);
 131                 subs->interface = -1;
 132         }
 133 }
 134
 135 static int snd_usb_create_stream(struct snd_usb_audio *chip, int ctrlif, int interface)
 136 {
 137         struct usb_device *dev = chip->dev;
 138         struct usb_host_interface *alts;
 139         struct usb_interface_descriptor *altsd;
 140         struct usb_interface *iface = usb_ifnum_to_if(dev, interface);
 141
 142         if (!iface) {
 143                 snd_printk(KERN_ERR "%d:%u:%d : does not exist\n",
 144                            dev->devnum, ctrlif, interface);
 145                 return -EINVAL;
 146         }
 147
 148         if (usb_interface_claimed(iface)) {
 149                 snd_printdd(KERN_INFO "%d:%d:%d: skipping, already claimed\n",
 150                                                 dev->devnum, ctrlif, interface);
 151                 return -EINVAL;
 152         }
 153
 154         alts = &iface->altsetting[0];
 155         altsd = get_iface_desc(alts);
 156         if ((altsd->bInterfaceClass == USB_CLASS_AUDIO ||
 157              altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC) &&
 158             altsd->bInterfaceSubClass == USB_SUBCLASS_MIDISTREAMING) {
 159                 int err = snd_usbmidi_create(chip->card, iface,
 160                                              &chip->midi_list, NULL);
 161                 if (err < 0) {
 162                         snd_printk(KERN_ERR "%d:%u:%d: cannot create sequencer device\n",
 163                                                 dev->devnum, ctrlif, interface);
 164                         return -EINVAL;
 165                 }
 166                 usb_driver_claim_interface(&usb_audio_driver, iface, (void *)-1L);
 167
 168                 return 0;
 169         }
 170
 171         if ((altsd->bInterfaceClass != USB_CLASS_AUDIO &&
 172              altsd->bInterfaceClass != USB_CLASS_VENDOR_SPEC) ||
 173             altsd->bInterfaceSubClass != USB_SUBCLASS_AUDIOSTREAMING) {
 174                 snd_printdd(KERN_ERR "%d:%u:%d: skipping non-supported interface %d\n",
 175                                         dev->devnum, ctrlif, interface, altsd->bInterfaceClass);
 176                 /* skip non-supported classes */
 177                 return -EINVAL;
 178         }
 179
 180         if (snd_usb_get_speed(dev) == USB_SPEED_LOW) {
 181                 snd_printk(KERN_ERR "low speed audio streaming not supported\n");
 182                 return -EINVAL;
 183         }
 184
 185         if (! snd_usb_parse_audio_endpoints(chip, interface)) {
 186                 usb_set_interface(dev, interface, 0); /* reset the current interface */
 187                 usb_driver_claim_interface(&usb_audio_driver, iface, (void *)-1L);
 188                 return -EINVAL;
 189         }
 190
 191         return 0;
 192 }
 193
 194 /*
 195  * parse audio control descriptor and create pcm/midi streams
 196  */
 197 static int snd_usb_create_streams(struct snd_usb_audio *chip, int ctrlif)
 198 {
 199         struct usb_device *dev = chip->dev;
 200         struct usb_host_interface *host_iface;
 201         struct usb_interface_descriptor *altsd;
 202         void *control_header;
 203         int i, protocol;
 204
 205         /* find audiocontrol interface */
 206         host_iface = &usb_ifnum_to_if(dev, ctrlif)->altsetting[0];
 207         control_header = snd_usb_find_csint_desc(host_iface->extra,
 208                                                  host_iface->extralen,
 209                                                  NULL, UAC_HEADER);
 210         altsd = get_iface_desc(host_iface);
 211         protocol = altsd->bInterfaceProtocol;
 212
 213         if (!control_header) {
 214                 snd_printk(KERN_ERR "cannot find UAC_HEADER\n");
 215                 return -EINVAL;
 216         }
 217
 218         switch (protocol) {
 219         default:
 220                 snd_printdd(KERN_WARNING "unknown interface protocol %#02x, assuming v1\n",
 221                             protocol);
 222                 /* fall through */
 223
 224         case UAC_VERSION_1: {
 225                 struct uac1_ac_header_descriptor *h1 = control_header;
 226
 227                 if (!h1->bInCollection) {
 228                         snd_printk(KERN_INFO "skipping empty audio interface (v1)\n");
 229                         return -EINVAL;
 230                 }
 231
 232                 if (h1->bLength < sizeof(*h1) + h1->bInCollection) {
 233                         snd_printk(KERN_ERR "invalid UAC_HEADER (v1)\n");
 234                         return -EINVAL;
 235                 }
 236
 237                 for (i = 0; i < h1->bInCollection; i++)
 238                         snd_usb_create_stream(chip, ctrlif, h1->baInterfaceNr[i]);
 239
 240                 break;
 241         }
 242
 243         case UAC_VERSION_2: {
 244                 struct usb_interface_assoc_descriptor *assoc =
 245                         usb_ifnum_to_if(dev, ctrlif)->intf_assoc;
 246
 247                 if (!assoc) {
 248                         snd_printk(KERN_ERR "Audio class v2 interfaces need an interface association\n");
 249                         return -EINVAL;
 250                 }
 251
 252                 for (i = 0; i < assoc->bInterfaceCount; i++) {
 253                         int intf = assoc->bFirstInterface + i;
 254
 255                         if (intf != ctrlif)
 256                                 snd_usb_create_stream(chip, ctrlif, intf);
 257                 }
 258
 259                 break;
 260         }
 261         }
 262
 263         return 0;
 264 }
 265
 266 /*
 267  * free the chip instance
 268  *
 269  * here we have to do not much, since pcm and controls are already freed
 270  *
 271  */
 272
 273 static int snd_usb_audio_free(struct snd_usb_audio *chip)
 274 {
 275         kfree(chip);
 276         return 0;
 277 }
 278
 279 static int snd_usb_audio_dev_free(struct snd_device *device)
 280 {
 281         struct snd_usb_audio *chip = device->device_data;
 282         return snd_usb_audio_free(chip);
 283 }
 284
 285
 286 /*
 287  * create a chip instance and set its names.
 288  */
 289 static int snd_usb_audio_create(struct usb_device *dev, int idx,
 290                                 const struct snd_usb_audio_quirk *quirk,
 291                                 struct snd_usb_audio **rchip)
 292 {
 293         struct snd_card *card;
 294         struct snd_usb_audio *chip;
 295         int err, len;
 296         char component[14];
 297         static struct snd_device_ops ops = {
 298                 .dev_free =     snd_usb_audio_dev_free,
 299         };
 300
 301         *rchip = NULL;
 302
 303         if (snd_usb_get_speed(dev) != USB_SPEED_LOW &&
 304             snd_usb_get_speed(dev) != USB_SPEED_FULL &&
 305             snd_usb_get_speed(dev) != USB_SPEED_HIGH) {
 306                 snd_printk(KERN_ERR "unknown device speed %d\n", snd_usb_get_speed(dev));
 307                 return -ENXIO;
 308         }
 309
 310         err = snd_card_create(index[idx], id[idx], THIS_MODULE, 0, &card);
 311         if (err < 0) {
 312                 snd_printk(KERN_ERR "cannot create card instance %d\n", idx);
 313                 return err;
 314         }
 315
 316         chip = kzalloc(sizeof(*chip), GFP_KERNEL);
 317         if (! chip) {
 318                 snd_card_free(card);
 319                 return -ENOMEM;
 320         }
 321
 322         chip->index = idx;
 323         chip->dev = dev;
 324         chip->card = card;
 325         chip->setup = device_setup[idx];
 326         chip->nrpacks = nrpacks;
 327         chip->async_unlink = async_unlink;
 328
 329         chip->usb_id = USB_ID(le16_to_cpu(dev->descriptor.idVendor),
 330                               le16_to_cpu(dev->descriptor.idProduct));
 331         INIT_LIST_HEAD(&chip->pcm_list);
 332         INIT_LIST_HEAD(&chip->midi_list);
 333         INIT_LIST_HEAD(&chip->mixer_list);
 334
 335         if ((err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, &ops)) < 0) {
 336                 snd_usb_audio_free(chip);
 337                 snd_card_free(card);
 338                 return err;
 339         }
 340
 341         strcpy(card->driver, "USB-Audio");
 342         sprintf(component, "USB%04x:%04x",
 343                 USB_ID_VENDOR(chip->usb_id), USB_ID_PRODUCT(chip->usb_id));
 344         snd_component_add(card, component);
 345
 346         /* retrieve the device string as shortname */
 347         if (quirk && quirk->product_name) {
 348                 strlcpy(card->shortname, quirk->product_name, sizeof(card->shortname));
 349         } else {
 350                 if (!dev->descriptor.iProduct ||
 351                     usb_string(dev, dev->descriptor.iProduct,
 352                     card->shortname, sizeof(card->shortname)) <= 0) {
 353                         /* no name available from anywhere, so use ID */
 354                         sprintf(card->shortname, "USB Device %#04x:%#04x",
 355                                 USB_ID_VENDOR(chip->usb_id),
 356                                 USB_ID_PRODUCT(chip->usb_id));
 357                 }
 358         }
 359
 360         /* retrieve the vendor and device strings as longname */
 361         if (quirk && quirk->vendor_name) {
 362                 len = strlcpy(card->longname, quirk->vendor_name, sizeof(card->longname));
 363         } else {
 364                 if (dev->descriptor.iManufacturer)
 365                         len = usb_string(dev, dev->descriptor.iManufacturer,
 366                                          card->longname, sizeof(card->longname));
 367                 else
 368                         len = 0;
 369                 /* we don't really care if there isn't any vendor string */
 370         }
 371         if (len > 0)
 372                 strlcat(card->longname, " ", sizeof(card->longname));
 373
 374         strlcat(card->longname, card->shortname, sizeof(card->longname));
 375
 376         len = strlcat(card->longname, " at ", sizeof(card->longname));
 377
 378         if (len < sizeof(card->longname))
 379                 usb_make_path(dev, card->longname + len, sizeof(card->longname) - len);
 380
 381         strlcat(card->longname,
 382                 snd_usb_get_speed(dev) == USB_SPEED_LOW ? ", low speed" :
 383                 snd_usb_get_speed(dev) == USB_SPEED_FULL ? ", full speed" :
 384                 ", high speed",
 385                 sizeof(card->longname));
 386
 387         snd_usb_audio_create_proc(chip);
 388
 389         *rchip = chip;
 390         return 0;
 391 }
 392
 393 /*
 394  * probe the active usb device
 395  *
 396  * note that this can be called multiple times per a device, when it
 397  * includes multiple audio control interfaces.
 398  *
 399  * thus we check the usb device pointer and creates the card instance
 400  * only at the first time.  the successive calls of this function will
 401  * append the pcm interface to the corresponding card.
 402  */
 403 static void *snd_usb_audio_probe(struct usb_device *dev,
 404                                  struct usb_interface *intf,
 405                                  const struct usb_device_id *usb_id)
 406 {
 407         const struct snd_usb_audio_quirk *quirk = (const struct snd_usb_audio_quirk *)usb_id->driver_info;
 408         int i, err;
 409         struct snd_usb_audio *chip;
 410         struct usb_host_interface *alts;
 411         int ifnum;
 412         u32 id;
 413
 414         alts = &intf->altsetting[0];
 415         ifnum = get_iface_desc(alts)->bInterfaceNumber;
 416         id = USB_ID(le16_to_cpu(dev->descriptor.idVendor),
 417                     le16_to_cpu(dev->descriptor.idProduct));
 418         if (quirk && quirk->ifnum >= 0 && ifnum != quirk->ifnum)
 419                 goto __err_val;
 420
 421         if (snd_usb_apply_boot_quirk(dev, intf, quirk) < 0)
 422                 goto __err_val;
 423
 424         /*
 425          * found a config.  now register to ALSA
 426          */
 427
 428         /* check whether it's already registered */
 429         chip = NULL;
 430         mutex_lock(&register_mutex);
 431         for (i = 0; i < SNDRV_CARDS; i++) {
 432                 if (usb_chip[i] && usb_chip[i]->dev == dev) {
 433                         if (usb_chip[i]->shutdown) {
 434                                 snd_printk(KERN_ERR "USB device is in the shutdown state, cannot create a card instance\n");
 435                                 goto __error;
 436                         }
 437                         chip = usb_chip[i];
 438                         break;
 439                 }
 440         }
 441         if (! chip) {
 442                 /* it's a fresh one.
 443                  * now look for an empty slot and create a new card instance
 444                  */
 445                 for (i = 0; i < SNDRV_CARDS; i++)
 446                         if (enable[i] && ! usb_chip[i] &&
 447                             (vid[i] == -1 || vid[i] == USB_ID_VENDOR(id)) &&
 448                             (pid[i] == -1 || pid[i] == USB_ID_PRODUCT(id))) {
 449                                 if (snd_usb_audio_create(dev, i, quirk, &chip) < 0) {
 450                                         goto __error;
 451                                 }
 452                                 snd_card_set_dev(chip->card, &intf->dev);
 453                                 break;
 454                         }
 455                 if (!chip) {
 456                         printk(KERN_ERR "no available usb audio device\n");
 457                         goto __error;
 458                 }
 459         }
 460
 461         chip->txfr_quirk = 0;
 462         err = 1; /* continue */
 463         if (quirk && quirk->ifnum != QUIRK_NO_INTERFACE) {
 464                 /* need some special handlings */
 465                 if ((err = snd_usb_create_quirk(chip, intf, &usb_audio_driver, quirk)) < 0)
 466                         goto __error;
 467         }
 468
 469         /*
 470          * For devices with more than one control interface, we assume the
 471          * first contains the audio controls. We might need a more specific
 472          * check here in the future.
 473          */
 474         if (!chip->ctrl_intf)
 475                 chip->ctrl_intf = alts;
 476
 477         if (err > 0) {
 478                 /* create normal USB audio interfaces */
 479                 if (snd_usb_create_streams(chip, ifnum) < 0 ||
 480                     snd_usb_create_mixer(chip, ifnum, ignore_ctl_error) < 0) {
 481                         goto __error;
 482                 }
 483         }
 484
 485         /* we are allowed to call snd_card_register() many times */
 486         if (snd_card_register(chip->card) < 0) {
 487                 goto __error;
 488         }
 489
 490         usb_chip[chip->index] = chip;
 491         chip->num_interfaces++;
 492         mutex_unlock(&register_mutex);
 493         return chip;
 494
 495  __error:
 496         if (chip && !chip->num_interfaces)
 497                 snd_card_free(chip->card);
 498         mutex_unlock(&register_mutex);
 499  __err_val:
 500         return NULL;
 501 }
 502
 503 /*
 504  * we need to take care of counter, since disconnection can be called also
 505  * many times as well as usb_audio_probe().
 506  */
 507 static void snd_usb_audio_disconnect(struct usb_device *dev, void *ptr)
 508 {
 509         struct snd_usb_audio *chip;
 510         struct snd_card *card;
 511         struct list_head *p;
 512
 513         if (ptr == (void *)-1L)
 514                 return;
 515
 516         chip = ptr;
 517         card = chip->card;
 518         mutex_lock(&register_mutex);
 519         chip->shutdown = 1;
 520         chip->num_interfaces--;
 521         if (chip->num_interfaces <= 0) {
 522                 snd_card_disconnect(card);
 523                 /* release the pcm resources */
 524                 list_for_each(p, &chip->pcm_list) {
 525                         snd_usb_stream_disconnect(p);
 526                 }
 527                 /* release the midi resources */
 528                 list_for_each(p, &chip->midi_list) {
 529                         snd_usbmidi_disconnect(p);
 530                 }
 531                 /* release mixer resources */
 532                 list_for_each(p, &chip->mixer_list) {
 533                         snd_usb_mixer_disconnect(p);
 534                 }
 535                 usb_chip[chip->index] = NULL;
 536                 mutex_unlock(&register_mutex);
 537                 snd_card_free_when_closed(card);
 538         } else {
 539                 mutex_unlock(&register_mutex);
 540         }
 541 }
 542
 543 /*
 544  * new 2.5 USB kernel API
 545  */
 546 static int usb_audio_probe(struct usb_interface *intf,
 547                            const struct usb_device_id *id)
 548 {
 549         void *chip;
 550         chip = snd_usb_audio_probe(interface_to_usbdev(intf), intf, id);
 551         if (chip) {
 552                 usb_set_intfdata(intf, chip);
 553                 return 0;
 554         } else
 555                 return -EIO;
 556 }
 557
 558 static void usb_audio_disconnect(struct usb_interface *intf)
 559 {
 560         snd_usb_audio_disconnect(interface_to_usbdev(intf),
 561                                  usb_get_intfdata(intf));
 562 }
 563
 564 #ifdef CONFIG_PM
 565 static int usb_audio_suspend(struct usb_interface *intf, pm_message_t message)
 566 {
 567         struct snd_usb_audio *chip = usb_get_intfdata(intf);
 568         struct list_head *p;
 569         struct snd_usb_stream *as;
 570
 571         if (chip == (void *)-1L)
 572                 return 0;
 573
 574         snd_power_change_state(chip->card, SNDRV_CTL_POWER_D3hot);
 575         if (!chip->num_suspended_intf++) {
 576                 list_for_each(p, &chip->pcm_list) {
 577                         as = list_entry(p, struct snd_usb_stream, list);
 578                         snd_pcm_suspend_all(as->pcm);
 579                 }
 580         }
 581
 582         return 0;
 583 }
 584
 585 static int usb_audio_resume(struct usb_interface *intf)
 586 {
 587         struct snd_usb_audio *chip = usb_get_intfdata(intf);
 588
 589         if (chip == (void *)-1L)
 590                 return 0;
 591         if (--chip->num_suspended_intf)
 592                 return 0;
 593         /*
 594          * ALSA leaves material resumption to user space
 595          * we just notify
 596          */
 597
 598         snd_power_change_state(chip->card, SNDRV_CTL_POWER_D0);
 599
 600         return 0;
 601 }
 602 #else
 603 #define usb_audio_suspend       NULL
 604 #define usb_audio_resume        NULL
 605 #endif          /* CONFIG_PM */
 606
 607 static struct usb_device_id usb_audio_ids [] = {
 608 #include "quirks-table.h"
 609     { .match_flags = (USB_DEVICE_ID_MATCH_INT_CLASS | USB_DEVICE_ID_MATCH_INT_SUBCLASS),
 610       .bInterfaceClass = USB_CLASS_AUDIO,
 611       .bInterfaceSubClass = USB_SUBCLASS_AUDIOCONTROL },
 612     { }                                         /* Terminating entry */
 613 };
 614
 615 MODULE_DEVICE_TABLE (usb, usb_audio_ids);
 616
 617 /*
 618  * entry point for linux usb interface
 619  */
 620
 621 static struct usb_driver usb_audio_driver = {
 622         .name =         "snd-usb-audio",
 623         .probe =        usb_audio_probe,
 624         .disconnect =   usb_audio_disconnect,
 625         .suspend =      usb_audio_suspend,
 626         .resume =       usb_audio_resume,
 627         .id_table =     usb_audio_ids,
 628 };
 629
 630 static int __init snd_usb_audio_init(void)
 631 {
 632         if (nrpacks < 1 || nrpacks > MAX_PACKS) {
 633                 printk(KERN_WARNING "invalid nrpacks value.\n");
 634                 return -EINVAL;
 635         }
 636         return usb_register(&usb_audio_driver);
 637 }
 638
 639 static void __exit snd_usb_audio_cleanup(void)
 640 {
 641         usb_deregister(&usb_audio_driver);
 642 }
 643
 644 module_init(snd_usb_audio_init);
 645 module_exit(snd_usb_audio_cleanup);