card.c 17.8 KB
Newer Older
D
Daniel Mack 已提交
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
/*
 *   (Tentative) USB Audio Driver for ALSA
 *
 *   Copyright (c) 2002 by Takashi Iwai <tiwai@suse.de>
 *
 *   Many codes borrowed from audio.c by
 *	    Alan Cox (alan@lxorguk.ukuu.org.uk)
 *	    Thomas Sailer (sailer@ife.ee.ethz.ch)
 *
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 *
 *  NOTES:
 *
 *   - async unlink should be used for avoiding the sleep inside lock.
 *     2.4.22 usb-uhci seems buggy for async unlinking and results in
 *     oops.  in such a cse, pass async_unlink=0 option.
 *   - the linked URBs would be preferred but not used so far because of
 *     the instability of unlinking.
 *   - type II is not supported properly.  there is no device which supports
 *     this type *correctly*.  SB extigy looks as if it supports, but it's
 *     indeed an AC3 stream packed in SPDIF frames (i.e. no real AC3 stream).
 */


#include <linux/bitops.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/usb.h>
#include <linux/moduleparam.h>
#include <linux/mutex.h>
#include <linux/usb/audio.h>
D
Daniel Mack 已提交
48
#include <linux/usb/audio-v2.h>
D
Daniel Mack 已提交
49 50 51 52 53 54 55 56 57 58

#include <sound/core.h>
#include <sound/info.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/initval.h>

#include "usbaudio.h"
#include "card.h"
#include "midi.h"
59
#include "mixer.h"
D
Daniel Mack 已提交
60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128
#include "proc.h"
#include "quirks.h"
#include "endpoint.h"
#include "helper.h"
#include "debug.h"
#include "pcm.h"
#include "urb.h"
#include "format.h"

MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
MODULE_DESCRIPTION("USB Audio");
MODULE_LICENSE("GPL");
MODULE_SUPPORTED_DEVICE("{{Generic,USB Audio}}");


static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;	/* Index 0-MAX */
static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;	/* ID for this card */
static int enable[SNDRV_CARDS] = SNDRV_DEFAULT_ENABLE_PNP;/* Enable this card */
/* Vendor/product IDs for this card */
static int vid[SNDRV_CARDS] = { [0 ... (SNDRV_CARDS-1)] = -1 };
static int pid[SNDRV_CARDS] = { [0 ... (SNDRV_CARDS-1)] = -1 };
static int nrpacks = 8;		/* max. number of packets per urb */
static int async_unlink = 1;
static int device_setup[SNDRV_CARDS]; /* device parameter for this card */
static int ignore_ctl_error;

module_param_array(index, int, NULL, 0444);
MODULE_PARM_DESC(index, "Index value for the USB audio adapter.");
module_param_array(id, charp, NULL, 0444);
MODULE_PARM_DESC(id, "ID string for the USB audio adapter.");
module_param_array(enable, bool, NULL, 0444);
MODULE_PARM_DESC(enable, "Enable USB audio adapter.");
module_param_array(vid, int, NULL, 0444);
MODULE_PARM_DESC(vid, "Vendor ID for the USB audio device.");
module_param_array(pid, int, NULL, 0444);
MODULE_PARM_DESC(pid, "Product ID for the USB audio device.");
module_param(nrpacks, int, 0644);
MODULE_PARM_DESC(nrpacks, "Max. number of packets per URB.");
module_param(async_unlink, bool, 0444);
MODULE_PARM_DESC(async_unlink, "Use async unlink mode.");
module_param_array(device_setup, int, NULL, 0444);
MODULE_PARM_DESC(device_setup, "Specific device setup (if needed).");
module_param(ignore_ctl_error, bool, 0444);
MODULE_PARM_DESC(ignore_ctl_error,
		 "Ignore errors from USB controller for mixer interfaces.");

/*
 * we keep the snd_usb_audio_t instances by ourselves for merging
 * the all interfaces on the same card as one sound device.
 */

static DEFINE_MUTEX(register_mutex);
static struct snd_usb_audio *usb_chip[SNDRV_CARDS];
static struct usb_driver usb_audio_driver;

/*
 * disconnect streams
 * called from snd_usb_audio_disconnect()
 */
static void snd_usb_stream_disconnect(struct list_head *head)
{
	int idx;
	struct snd_usb_stream *as;
	struct snd_usb_substream *subs;

	as = list_entry(head, struct snd_usb_stream, list);
	for (idx = 0; idx < 2; idx++) {
		subs = &as->substream[idx];
		if (!subs->num_formats)
129
			continue;
D
Daniel Mack 已提交
130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218
		snd_usb_release_substream_urbs(subs, 1);
		subs->interface = -1;
	}
}

static int snd_usb_create_stream(struct snd_usb_audio *chip, int ctrlif, int interface)
{
	struct usb_device *dev = chip->dev;
	struct usb_host_interface *alts;
	struct usb_interface_descriptor *altsd;
	struct usb_interface *iface = usb_ifnum_to_if(dev, interface);

	if (!iface) {
		snd_printk(KERN_ERR "%d:%u:%d : does not exist\n",
			   dev->devnum, ctrlif, interface);
		return -EINVAL;
	}

	if (usb_interface_claimed(iface)) {
		snd_printdd(KERN_INFO "%d:%d:%d: skipping, already claimed\n",
						dev->devnum, ctrlif, interface);
		return -EINVAL;
	}

	alts = &iface->altsetting[0];
	altsd = get_iface_desc(alts);
	if ((altsd->bInterfaceClass == USB_CLASS_AUDIO ||
	     altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC) &&
	    altsd->bInterfaceSubClass == USB_SUBCLASS_MIDISTREAMING) {
		int err = snd_usbmidi_create(chip->card, iface,
					     &chip->midi_list, NULL);
		if (err < 0) {
			snd_printk(KERN_ERR "%d:%u:%d: cannot create sequencer device\n",
						dev->devnum, ctrlif, interface);
			return -EINVAL;
		}
		usb_driver_claim_interface(&usb_audio_driver, iface, (void *)-1L);

		return 0;
	}

	if ((altsd->bInterfaceClass != USB_CLASS_AUDIO &&
	     altsd->bInterfaceClass != USB_CLASS_VENDOR_SPEC) ||
	    altsd->bInterfaceSubClass != USB_SUBCLASS_AUDIOSTREAMING) {
		snd_printdd(KERN_ERR "%d:%u:%d: skipping non-supported interface %d\n",
					dev->devnum, ctrlif, interface, altsd->bInterfaceClass);
		/* skip non-supported classes */
		return -EINVAL;
	}

	if (snd_usb_get_speed(dev) == USB_SPEED_LOW) {
		snd_printk(KERN_ERR "low speed audio streaming not supported\n");
		return -EINVAL;
	}

	if (! snd_usb_parse_audio_endpoints(chip, interface)) {
		usb_set_interface(dev, interface, 0); /* reset the current interface */
		usb_driver_claim_interface(&usb_audio_driver, iface, (void *)-1L);
		return -EINVAL;
	}

	return 0;
}

/*
 * parse audio control descriptor and create pcm/midi streams
 */
static int snd_usb_create_streams(struct snd_usb_audio *chip, int ctrlif)
{
	struct usb_device *dev = chip->dev;
	struct usb_host_interface *host_iface;
	struct usb_interface_descriptor *altsd;
	void *control_header;
	int i, protocol;

	/* find audiocontrol interface */
	host_iface = &usb_ifnum_to_if(dev, ctrlif)->altsetting[0];
	control_header = snd_usb_find_csint_desc(host_iface->extra,
						 host_iface->extralen,
						 NULL, UAC_HEADER);
	altsd = get_iface_desc(host_iface);
	protocol = altsd->bInterfaceProtocol;

	if (!control_header) {
		snd_printk(KERN_ERR "cannot find UAC_HEADER\n");
		return -EINVAL;
	}

	switch (protocol) {
219 220 221 222 223
	default:
		snd_printdd(KERN_WARNING "unknown interface protocol %#02x, assuming v1\n",
			    protocol);
		/* fall through */

D
Daniel Mack 已提交
224
	case UAC_VERSION_1: {
225
		struct uac1_ac_header_descriptor *h1 = control_header;
D
Daniel Mack 已提交
226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302

		if (!h1->bInCollection) {
			snd_printk(KERN_INFO "skipping empty audio interface (v1)\n");
			return -EINVAL;
		}

		if (h1->bLength < sizeof(*h1) + h1->bInCollection) {
			snd_printk(KERN_ERR "invalid UAC_HEADER (v1)\n");
			return -EINVAL;
		}

		for (i = 0; i < h1->bInCollection; i++)
			snd_usb_create_stream(chip, ctrlif, h1->baInterfaceNr[i]);

		break;
	}

	case UAC_VERSION_2: {
		struct usb_interface_assoc_descriptor *assoc =
			usb_ifnum_to_if(dev, ctrlif)->intf_assoc;

		if (!assoc) {
			snd_printk(KERN_ERR "Audio class v2 interfaces need an interface association\n");
			return -EINVAL;
		}

		for (i = 0; i < assoc->bInterfaceCount; i++) {
			int intf = assoc->bFirstInterface + i;

			if (intf != ctrlif)
				snd_usb_create_stream(chip, ctrlif, intf);
		}

		break;
	}
	}

	return 0;
}

/*
 * free the chip instance
 *
 * here we have to do not much, since pcm and controls are already freed
 *
 */

static int snd_usb_audio_free(struct snd_usb_audio *chip)
{
	kfree(chip);
	return 0;
}

static int snd_usb_audio_dev_free(struct snd_device *device)
{
	struct snd_usb_audio *chip = device->device_data;
	return snd_usb_audio_free(chip);
}


/*
 * create a chip instance and set its names.
 */
static int snd_usb_audio_create(struct usb_device *dev, int idx,
				const struct snd_usb_audio_quirk *quirk,
				struct snd_usb_audio **rchip)
{
	struct snd_card *card;
	struct snd_usb_audio *chip;
	int err, len;
	char component[14];
	static struct snd_device_ops ops = {
		.dev_free =	snd_usb_audio_dev_free,
	};

	*rchip = NULL;

303 304 305 306 307 308 309
	switch (snd_usb_get_speed(dev)) {
	case USB_SPEED_LOW:
	case USB_SPEED_FULL:
	case USB_SPEED_HIGH:
	case USB_SPEED_SUPER:
		break;
	default:
D
Daniel Mack 已提交
310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325
		snd_printk(KERN_ERR "unknown device speed %d\n", snd_usb_get_speed(dev));
		return -ENXIO;
	}

	err = snd_card_create(index[idx], id[idx], THIS_MODULE, 0, &card);
	if (err < 0) {
		snd_printk(KERN_ERR "cannot create card instance %d\n", idx);
		return err;
	}

	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
	if (! chip) {
		snd_card_free(card);
		return -ENOMEM;
	}

326
	mutex_init(&chip->shutdown_mutex);
D
Daniel Mack 已提交
327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385
	chip->index = idx;
	chip->dev = dev;
	chip->card = card;
	chip->setup = device_setup[idx];
	chip->nrpacks = nrpacks;
	chip->async_unlink = async_unlink;

	chip->usb_id = USB_ID(le16_to_cpu(dev->descriptor.idVendor),
			      le16_to_cpu(dev->descriptor.idProduct));
	INIT_LIST_HEAD(&chip->pcm_list);
	INIT_LIST_HEAD(&chip->midi_list);
	INIT_LIST_HEAD(&chip->mixer_list);

	if ((err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, &ops)) < 0) {
		snd_usb_audio_free(chip);
		snd_card_free(card);
		return err;
	}

	strcpy(card->driver, "USB-Audio");
	sprintf(component, "USB%04x:%04x",
		USB_ID_VENDOR(chip->usb_id), USB_ID_PRODUCT(chip->usb_id));
	snd_component_add(card, component);

	/* retrieve the device string as shortname */
	if (quirk && quirk->product_name) {
		strlcpy(card->shortname, quirk->product_name, sizeof(card->shortname));
	} else {
		if (!dev->descriptor.iProduct ||
		    usb_string(dev, dev->descriptor.iProduct,
		    card->shortname, sizeof(card->shortname)) <= 0) {
			/* no name available from anywhere, so use ID */
			sprintf(card->shortname, "USB Device %#04x:%#04x",
				USB_ID_VENDOR(chip->usb_id),
				USB_ID_PRODUCT(chip->usb_id));
		}
	}

	/* retrieve the vendor and device strings as longname */
	if (quirk && quirk->vendor_name) {
		len = strlcpy(card->longname, quirk->vendor_name, sizeof(card->longname));
	} else {
		if (dev->descriptor.iManufacturer)
			len = usb_string(dev, dev->descriptor.iManufacturer,
					 card->longname, sizeof(card->longname));
		else
			len = 0;
		/* we don't really care if there isn't any vendor string */
	}
	if (len > 0)
		strlcat(card->longname, " ", sizeof(card->longname));

	strlcat(card->longname, card->shortname, sizeof(card->longname));

	len = strlcat(card->longname, " at ", sizeof(card->longname));

	if (len < sizeof(card->longname))
		usb_make_path(dev, card->longname + len, sizeof(card->longname) - len);

386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401
	switch (snd_usb_get_speed(dev)) {
	case USB_SPEED_LOW:
		strlcat(card->longname, ", low speed", sizeof(card->longname));
		break;
	case USB_SPEED_FULL:
		strlcat(card->longname, ", full speed", sizeof(card->longname));
		break;
	case USB_SPEED_HIGH:
		strlcat(card->longname, ", high speed", sizeof(card->longname));
		break;
	case USB_SPEED_SUPER:
		strlcat(card->longname, ", super speed", sizeof(card->longname));
		break;
	default:
		break;
	}
D
Daniel Mack 已提交
402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484

	snd_usb_audio_create_proc(chip);

	*rchip = chip;
	return 0;
}

/*
 * probe the active usb device
 *
 * note that this can be called multiple times per a device, when it
 * includes multiple audio control interfaces.
 *
 * thus we check the usb device pointer and creates the card instance
 * only at the first time.  the successive calls of this function will
 * append the pcm interface to the corresponding card.
 */
static void *snd_usb_audio_probe(struct usb_device *dev,
				 struct usb_interface *intf,
				 const struct usb_device_id *usb_id)
{
	const struct snd_usb_audio_quirk *quirk = (const struct snd_usb_audio_quirk *)usb_id->driver_info;
	int i, err;
	struct snd_usb_audio *chip;
	struct usb_host_interface *alts;
	int ifnum;
	u32 id;

	alts = &intf->altsetting[0];
	ifnum = get_iface_desc(alts)->bInterfaceNumber;
	id = USB_ID(le16_to_cpu(dev->descriptor.idVendor),
		    le16_to_cpu(dev->descriptor.idProduct));
	if (quirk && quirk->ifnum >= 0 && ifnum != quirk->ifnum)
		goto __err_val;

	if (snd_usb_apply_boot_quirk(dev, intf, quirk) < 0)
		goto __err_val;

	/*
	 * found a config.  now register to ALSA
	 */

	/* check whether it's already registered */
	chip = NULL;
	mutex_lock(&register_mutex);
	for (i = 0; i < SNDRV_CARDS; i++) {
		if (usb_chip[i] && usb_chip[i]->dev == dev) {
			if (usb_chip[i]->shutdown) {
				snd_printk(KERN_ERR "USB device is in the shutdown state, cannot create a card instance\n");
				goto __error;
			}
			chip = usb_chip[i];
			break;
		}
	}
	if (! chip) {
		/* it's a fresh one.
		 * now look for an empty slot and create a new card instance
		 */
		for (i = 0; i < SNDRV_CARDS; i++)
			if (enable[i] && ! usb_chip[i] &&
			    (vid[i] == -1 || vid[i] == USB_ID_VENDOR(id)) &&
			    (pid[i] == -1 || pid[i] == USB_ID_PRODUCT(id))) {
				if (snd_usb_audio_create(dev, i, quirk, &chip) < 0) {
					goto __error;
				}
				snd_card_set_dev(chip->card, &intf->dev);
				break;
			}
		if (!chip) {
			printk(KERN_ERR "no available usb audio device\n");
			goto __error;
		}
	}

	chip->txfr_quirk = 0;
	err = 1; /* continue */
	if (quirk && quirk->ifnum != QUIRK_NO_INTERFACE) {
		/* need some special handlings */
		if ((err = snd_usb_create_quirk(chip, intf, &usb_audio_driver, quirk)) < 0)
			goto __error;
	}

485 486 487 488 489 490 491
	/*
	 * For devices with more than one control interface, we assume the
	 * first contains the audio controls. We might need a more specific
	 * check here in the future.
	 */
	if (!chip->ctrl_intf)
		chip->ctrl_intf = alts;
492

D
Daniel Mack 已提交
493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534
	if (err > 0) {
		/* create normal USB audio interfaces */
		if (snd_usb_create_streams(chip, ifnum) < 0 ||
		    snd_usb_create_mixer(chip, ifnum, ignore_ctl_error) < 0) {
			goto __error;
		}
	}

	/* we are allowed to call snd_card_register() many times */
	if (snd_card_register(chip->card) < 0) {
		goto __error;
	}

	usb_chip[chip->index] = chip;
	chip->num_interfaces++;
	mutex_unlock(&register_mutex);
	return chip;

 __error:
	if (chip && !chip->num_interfaces)
		snd_card_free(chip->card);
	mutex_unlock(&register_mutex);
 __err_val:
	return NULL;
}

/*
 * we need to take care of counter, since disconnection can be called also
 * many times as well as usb_audio_probe().
 */
static void snd_usb_audio_disconnect(struct usb_device *dev, void *ptr)
{
	struct snd_usb_audio *chip;
	struct snd_card *card;
	struct list_head *p;

	if (ptr == (void *)-1L)
		return;

	chip = ptr;
	card = chip->card;
	mutex_lock(&register_mutex);
535
	mutex_lock(&chip->shutdown_mutex);
D
Daniel Mack 已提交
536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552
	chip->shutdown = 1;
	chip->num_interfaces--;
	if (chip->num_interfaces <= 0) {
		snd_card_disconnect(card);
		/* release the pcm resources */
		list_for_each(p, &chip->pcm_list) {
			snd_usb_stream_disconnect(p);
		}
		/* release the midi resources */
		list_for_each(p, &chip->midi_list) {
			snd_usbmidi_disconnect(p);
		}
		/* release mixer resources */
		list_for_each(p, &chip->mixer_list) {
			snd_usb_mixer_disconnect(p);
		}
		usb_chip[chip->index] = NULL;
553
		mutex_unlock(&chip->shutdown_mutex);
D
Daniel Mack 已提交
554 555 556
		mutex_unlock(&register_mutex);
		snd_card_free_when_closed(card);
	} else {
557
		mutex_unlock(&chip->shutdown_mutex);
D
Daniel Mack 已提交
558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620
		mutex_unlock(&register_mutex);
	}
}

/*
 * new 2.5 USB kernel API
 */
static int usb_audio_probe(struct usb_interface *intf,
			   const struct usb_device_id *id)
{
	void *chip;
	chip = snd_usb_audio_probe(interface_to_usbdev(intf), intf, id);
	if (chip) {
		usb_set_intfdata(intf, chip);
		return 0;
	} else
		return -EIO;
}

static void usb_audio_disconnect(struct usb_interface *intf)
{
	snd_usb_audio_disconnect(interface_to_usbdev(intf),
				 usb_get_intfdata(intf));
}

#ifdef CONFIG_PM
static int usb_audio_suspend(struct usb_interface *intf, pm_message_t message)
{
	struct snd_usb_audio *chip = usb_get_intfdata(intf);
	struct list_head *p;
	struct snd_usb_stream *as;

	if (chip == (void *)-1L)
		return 0;

	snd_power_change_state(chip->card, SNDRV_CTL_POWER_D3hot);
	if (!chip->num_suspended_intf++) {
		list_for_each(p, &chip->pcm_list) {
			as = list_entry(p, struct snd_usb_stream, list);
			snd_pcm_suspend_all(as->pcm);
		}
	}

	return 0;
}

static int usb_audio_resume(struct usb_interface *intf)
{
	struct snd_usb_audio *chip = usb_get_intfdata(intf);

	if (chip == (void *)-1L)
		return 0;
	if (--chip->num_suspended_intf)
		return 0;
	/*
	 * ALSA leaves material resumption to user space
	 * we just notify
	 */

	snd_power_change_state(chip->card, SNDRV_CTL_POWER_D0);

	return 0;
}
621 622 623
#else
#define usb_audio_suspend	NULL
#define usb_audio_resume	NULL
D
Daniel Mack 已提交
624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664
#endif		/* CONFIG_PM */

static struct usb_device_id usb_audio_ids [] = {
#include "quirks-table.h"
    { .match_flags = (USB_DEVICE_ID_MATCH_INT_CLASS | USB_DEVICE_ID_MATCH_INT_SUBCLASS),
      .bInterfaceClass = USB_CLASS_AUDIO,
      .bInterfaceSubClass = USB_SUBCLASS_AUDIOCONTROL },
    { }						/* Terminating entry */
};

MODULE_DEVICE_TABLE (usb, usb_audio_ids);

/*
 * entry point for linux usb interface
 */

static struct usb_driver usb_audio_driver = {
	.name =		"snd-usb-audio",
	.probe =	usb_audio_probe,
	.disconnect =	usb_audio_disconnect,
	.suspend =	usb_audio_suspend,
	.resume =	usb_audio_resume,
	.id_table =	usb_audio_ids,
};

static int __init snd_usb_audio_init(void)
{
	if (nrpacks < 1 || nrpacks > MAX_PACKS) {
		printk(KERN_WARNING "invalid nrpacks value.\n");
		return -EINVAL;
	}
	return usb_register(&usb_audio_driver);
}

static void __exit snd_usb_audio_cleanup(void)
{
	usb_deregister(&usb_audio_driver);
}

module_init(snd_usb_audio_init);
module_exit(snd_usb_audio_cleanup);