diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
new file mode 100644
index 0000000..84b0bbd
--- /dev/null
+++ b/sound/usb/usbaudio.c
@@ -0,0 +1,3337 @@
+/*
+ *   (Tentative) USB Audio Driver for ALSA
+ *
+ *   Main and PCM part
+ *
+ *   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 <sound/driver.h>
+#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 <sound/core.h>
+#include <sound/info.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <sound/initval.h>
+
+#include "usbaudio.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 */
+static int vid[SNDRV_CARDS] = { [0 ... (SNDRV_CARDS-1)] = -1 }; /* Vendor ID for this card */
+static int pid[SNDRV_CARDS] = { [0 ... (SNDRV_CARDS-1)] = -1 }; /* Product ID for this card */
+static int nrpacks = 4;		/* max. number of packets per urb */
+static int async_unlink = 1;
+
+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, 0444);
+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.");
+
+
+/*
+ * debug the h/w constraints
+ */
+/* #define HW_CONST_DEBUG */
+
+
+/*
+ *
+ */
+
+#define MAX_PACKS	10
+#define MAX_PACKS_HS	(MAX_PACKS * 8)	/* in high speed mode */
+#define MAX_URBS	5	/* max. 20ms long packets */
+#define SYNC_URBS	2	/* always two urbs for sync */
+#define MIN_PACKS_URB	1	/* minimum 1 packet per urb */
+
+typedef struct snd_usb_substream snd_usb_substream_t;
+typedef struct snd_usb_stream snd_usb_stream_t;
+typedef struct snd_urb_ctx snd_urb_ctx_t;
+
+struct audioformat {
+	struct list_head list;
+	snd_pcm_format_t format;	/* format type */
+	unsigned int channels;		/* # channels */
+	unsigned int fmt_type;		/* USB audio format type (1-3) */
+	unsigned int frame_size;	/* samples per frame for non-audio */
+	int iface;			/* interface number */
+	unsigned char altsetting;	/* corresponding alternate setting */
+	unsigned char altset_idx;	/* array index of altenate setting */
+	unsigned char attributes;	/* corresponding attributes of cs endpoint */
+	unsigned char endpoint;		/* endpoint */
+	unsigned char ep_attr;		/* endpoint attributes */
+	unsigned int maxpacksize;	/* max. packet size */
+	unsigned int rates;		/* rate bitmasks */
+	unsigned int rate_min, rate_max;	/* min/max rates */
+	unsigned int nr_rates;		/* number of rate table entries */
+	unsigned int *rate_table;	/* rate table */
+};
+
+struct snd_urb_ctx {
+	struct urb *urb;
+	snd_usb_substream_t *subs;
+	int index;	/* index for urb array */
+	int packets;	/* number of packets per urb */
+	int transfer;	/* transferred size */
+	char *buf;	/* buffer for capture */
+};
+
+struct snd_urb_ops {
+	int (*prepare)(snd_usb_substream_t *subs, snd_pcm_runtime_t *runtime, struct urb *u);
+	int (*retire)(snd_usb_substream_t *subs, snd_pcm_runtime_t *runtime, struct urb *u);
+	int (*prepare_sync)(snd_usb_substream_t *subs, snd_pcm_runtime_t *runtime, struct urb *u);
+	int (*retire_sync)(snd_usb_substream_t *subs, snd_pcm_runtime_t *runtime, struct urb *u);
+};
+
+struct snd_usb_substream {
+	snd_usb_stream_t *stream;
+	struct usb_device *dev;
+	snd_pcm_substream_t *pcm_substream;
+	int direction;	/* playback or capture */
+	int interface;	/* current interface */
+	int endpoint;	/* assigned endpoint */
+	struct audioformat *cur_audiofmt;	/* current audioformat pointer (for hw_params callback) */
+	unsigned int cur_rate;		/* current rate (for hw_params callback) */
+	unsigned int period_bytes;	/* current period bytes (for hw_params callback) */
+	unsigned int format;     /* USB data format */
+	unsigned int datapipe;   /* the data i/o pipe */
+	unsigned int syncpipe;   /* 1 - async out or adaptive in */
+	unsigned int syncinterval;  /* P for adaptive mode, 0 otherwise */
+	unsigned int freqn;      /* nominal sampling rate in fs/fps in Q16.16 format */
+	unsigned int freqm;      /* momentary sampling rate in fs/fps in Q16.16 format */
+	unsigned int freqmax;    /* maximum sampling rate, used for buffer management */
+	unsigned int phase;      /* phase accumulator */
+	unsigned int maxpacksize;	/* max packet size in bytes */
+	unsigned int maxframesize;	/* max packet size in frames */
+	unsigned int curpacksize;	/* current packet size in bytes (for capture) */
+	unsigned int curframesize;	/* current packet size in frames (for capture) */
+	unsigned int fill_max: 1;	/* fill max packet size always */
+	unsigned int fmt_type;		/* USB audio format type (1-3) */
+
+	unsigned int running: 1;	/* running status */
+
+	unsigned int hwptr;			/* free frame position in the buffer (only for playback) */
+	unsigned int hwptr_done;			/* processed frame position in the buffer */
+	unsigned int transfer_sched;		/* scheduled frames since last period (for playback) */
+	unsigned int transfer_done;		/* processed frames since last period update */
+	unsigned long active_mask;	/* bitmask of active urbs */
+	unsigned long unlink_mask;	/* bitmask of unlinked urbs */
+
+	unsigned int nurbs;			/* # urbs */
+	snd_urb_ctx_t dataurb[MAX_URBS];	/* data urb table */
+	snd_urb_ctx_t syncurb[SYNC_URBS];	/* sync urb table */
+	char syncbuf[SYNC_URBS * MAX_PACKS * 4]; /* sync buffer; it's so small - let's get static */
+	char *tmpbuf;			/* temporary buffer for playback */
+
+	u64 formats;			/* format bitmasks (all or'ed) */
+	unsigned int num_formats;		/* number of supported audio formats (list) */
+	struct list_head fmt_list;	/* format list */
+	spinlock_t lock;
+
+	struct snd_urb_ops ops;		/* callbacks (must be filled at init) */
+};
+
+
+struct snd_usb_stream {
+	snd_usb_audio_t *chip;
+	snd_pcm_t *pcm;
+	int pcm_index;
+	unsigned int fmt_type;		/* USB audio format type (1-3) */
+	snd_usb_substream_t substream[2];
+	struct list_head list;
+};
+
+
+/*
+ * we keep the snd_usb_audio_t instances by ourselves for merging
+ * the all interfaces on the same card as one sound device.
+ */
+
+static DECLARE_MUTEX(register_mutex);
+static snd_usb_audio_t *usb_chip[SNDRV_CARDS];
+
+
+/*
+ * convert a sampling rate into our full speed format (fs/1000 in Q16.16)
+ * this will overflow at approx 524 kHz
+ */
+inline static unsigned get_usb_full_speed_rate(unsigned int rate)
+{
+	return ((rate << 13) + 62) / 125;
+}
+
+/*
+ * convert a sampling rate into USB high speed format (fs/8000 in Q16.16)
+ * this will overflow at approx 4 MHz
+ */
+inline static unsigned get_usb_high_speed_rate(unsigned int rate)
+{
+	return ((rate << 10) + 62) / 125;
+}
+
+/* convert our full speed USB rate into sampling rate in Hz */
+inline static unsigned get_full_speed_hz(unsigned int usb_rate)
+{
+	return (usb_rate * 125 + (1 << 12)) >> 13;
+}
+
+/* convert our high speed USB rate into sampling rate in Hz */
+inline static unsigned get_high_speed_hz(unsigned int usb_rate)
+{
+	return (usb_rate * 125 + (1 << 9)) >> 10;
+}
+
+
+/*
+ * prepare urb for full speed capture sync pipe
+ *
+ * fill the length and offset of each urb descriptor.
+ * the fixed 10.14 frequency is passed through the pipe.
+ */
+static int prepare_capture_sync_urb(snd_usb_substream_t *subs,
+				    snd_pcm_runtime_t *runtime,
+				    struct urb *urb)
+{
+	unsigned char *cp = urb->transfer_buffer;
+	snd_urb_ctx_t *ctx = (snd_urb_ctx_t *)urb->context;
+	int i, offs;
+
+	urb->number_of_packets = ctx->packets;
+	urb->dev = ctx->subs->dev; /* we need to set this at each time */
+	for (i = offs = 0; i < urb->number_of_packets; i++, offs += 4, cp += 4) {
+		urb->iso_frame_desc[i].length = 3;
+		urb->iso_frame_desc[i].offset = offs;
+		cp[0] = subs->freqn >> 2;
+		cp[1] = subs->freqn >> 10;
+		cp[2] = subs->freqn >> 18;
+	}
+	return 0;
+}
+
+/*
+ * prepare urb for high speed capture sync pipe
+ *
+ * fill the length and offset of each urb descriptor.
+ * the fixed 12.13 frequency is passed as 16.16 through the pipe.
+ */
+static int prepare_capture_sync_urb_hs(snd_usb_substream_t *subs,
+				       snd_pcm_runtime_t *runtime,
+				       struct urb *urb)
+{
+	unsigned char *cp = urb->transfer_buffer;
+	snd_urb_ctx_t *ctx = (snd_urb_ctx_t *)urb->context;
+	int i, offs;
+
+	urb->number_of_packets = ctx->packets;
+	urb->dev = ctx->subs->dev; /* we need to set this at each time */
+	for (i = offs = 0; i < urb->number_of_packets; i++, offs += 4, cp += 4) {
+		urb->iso_frame_desc[i].length = 4;
+		urb->iso_frame_desc[i].offset = offs;
+		cp[0] = subs->freqn;
+		cp[1] = subs->freqn >> 8;
+		cp[2] = subs->freqn >> 16;
+		cp[3] = subs->freqn >> 24;
+	}
+	return 0;
+}
+
+/*
+ * process after capture sync complete
+ * - nothing to do
+ */
+static int retire_capture_sync_urb(snd_usb_substream_t *subs,
+				   snd_pcm_runtime_t *runtime,
+				   struct urb *urb)
+{
+	return 0;
+}
+
+/*
+ * prepare urb for capture data pipe
+ *
+ * fill the offset and length of each descriptor.
+ *
+ * we use a temporary buffer to write the captured data.
+ * since the length of written data is determined by host, we cannot
+ * write onto the pcm buffer directly...  the data is thus copied
+ * later at complete callback to the global buffer.
+ */
+static int prepare_capture_urb(snd_usb_substream_t *subs,
+			       snd_pcm_runtime_t *runtime,
+			       struct urb *urb)
+{
+	int i, offs;
+	unsigned long flags;
+	snd_urb_ctx_t *ctx = (snd_urb_ctx_t *)urb->context;
+
+	offs = 0;
+	urb->dev = ctx->subs->dev; /* we need to set this at each time */
+	urb->number_of_packets = 0;
+	spin_lock_irqsave(&subs->lock, flags);
+	for (i = 0; i < ctx->packets; i++) {
+		urb->iso_frame_desc[i].offset = offs;
+		urb->iso_frame_desc[i].length = subs->curpacksize;
+		offs += subs->curpacksize;
+		urb->number_of_packets++;
+		subs->transfer_sched += subs->curframesize;
+		if (subs->transfer_sched >= runtime->period_size) {
+			subs->transfer_sched -= runtime->period_size;
+			break;
+		}
+	}
+	spin_unlock_irqrestore(&subs->lock, flags);
+	urb->transfer_buffer = ctx->buf;
+	urb->transfer_buffer_length = offs;
+#if 0 // for check
+	if (! urb->bandwidth) {
+		int bustime;
+		bustime = usb_check_bandwidth(urb->dev, urb);
+		if (bustime < 0)
+			return bustime;
+		printk("urb %d: bandwidth = %d (packets = %d)\n", ctx->index, bustime, urb->number_of_packets);
+		usb_claim_bandwidth(urb->dev, urb, bustime, 1);
+	}
+#endif // for check
+	return 0;
+}
+
+/*
+ * process after capture complete
+ *
+ * copy the data from each desctiptor to the pcm buffer, and
+ * update the current position.
+ */
+static int retire_capture_urb(snd_usb_substream_t *subs,
+			      snd_pcm_runtime_t *runtime,
+			      struct urb *urb)
+{
+	unsigned long flags;
+	unsigned char *cp;
+	int i;
+	unsigned int stride, len, oldptr;
+
+	stride = runtime->frame_bits >> 3;
+
+	for (i = 0; i < urb->number_of_packets; i++) {
+		cp = (unsigned char *)urb->transfer_buffer + urb->iso_frame_desc[i].offset;
+		if (urb->iso_frame_desc[i].status) {
+			snd_printd(KERN_ERR "frame %d active: %d\n", i, urb->iso_frame_desc[i].status);
+			// continue;
+		}
+		len = urb->iso_frame_desc[i].actual_length / stride;
+		if (! len)
+			continue;
+		/* update the current pointer */
+		spin_lock_irqsave(&subs->lock, flags);
+		oldptr = subs->hwptr_done;
+		subs->hwptr_done += len;
+		if (subs->hwptr_done >= runtime->buffer_size)
+			subs->hwptr_done -= runtime->buffer_size;
+		subs->transfer_done += len;
+		spin_unlock_irqrestore(&subs->lock, flags);
+		/* copy a data chunk */
+		if (oldptr + len > runtime->buffer_size) {
+			unsigned int cnt = runtime->buffer_size - oldptr;
+			unsigned int blen = cnt * stride;
+			memcpy(runtime->dma_area + oldptr * stride, cp, blen);
+			memcpy(runtime->dma_area, cp + blen, len * stride - blen);
+		} else {
+			memcpy(runtime->dma_area + oldptr * stride, cp, len * stride);
+		}
+		/* update the pointer, call callback if necessary */
+		spin_lock_irqsave(&subs->lock, flags);
+		if (subs->transfer_done >= runtime->period_size) {
+			subs->transfer_done -= runtime->period_size;
+			spin_unlock_irqrestore(&subs->lock, flags);
+			snd_pcm_period_elapsed(subs->pcm_substream);
+		} else
+			spin_unlock_irqrestore(&subs->lock, flags);
+	}
+	return 0;
+}
+
+
+/*
+ * prepare urb for full speed playback sync pipe
+ *
+ * set up the offset and length to receive the current frequency.
+ */
+
+static int prepare_playback_sync_urb(snd_usb_substream_t *subs,
+				     snd_pcm_runtime_t *runtime,
+				     struct urb *urb)
+{
+	int i, offs;
+	snd_urb_ctx_t *ctx = (snd_urb_ctx_t *)urb->context;
+
+	urb->number_of_packets = ctx->packets;
+	urb->dev = ctx->subs->dev; /* we need to set this at each time */
+	for (i = offs = 0; i < urb->number_of_packets; i++, offs += 4) {
+		urb->iso_frame_desc[i].length = 3;
+		urb->iso_frame_desc[i].offset = offs;
+	}
+	return 0;
+}
+
+/*
+ * prepare urb for high speed playback sync pipe
+ *
+ * set up the offset and length to receive the current frequency.
+ */
+
+static int prepare_playback_sync_urb_hs(snd_usb_substream_t *subs,
+					snd_pcm_runtime_t *runtime,
+					struct urb *urb)
+{
+	int i, offs;
+	snd_urb_ctx_t *ctx = (snd_urb_ctx_t *)urb->context;
+
+	urb->number_of_packets = ctx->packets;
+	urb->dev = ctx->subs->dev; /* we need to set this at each time */
+	for (i = offs = 0; i < urb->number_of_packets; i++, offs += 4) {
+		urb->iso_frame_desc[i].length = 4;
+		urb->iso_frame_desc[i].offset = offs;
+	}
+	return 0;
+}
+
+/*
+ * process after full speed playback sync complete
+ *
+ * retrieve the current 10.14 frequency from pipe, and set it.
+ * the value is referred in prepare_playback_urb().
+ */
+static int retire_playback_sync_urb(snd_usb_substream_t *subs,
+				    snd_pcm_runtime_t *runtime,
+				    struct urb *urb)
+{
+	int i;
+	unsigned int f, found;
+	unsigned char *cp = urb->transfer_buffer;
+	unsigned long flags;
+
+	found = 0;
+	for (i = 0; i < urb->number_of_packets; i++, cp += 4) {
+		if (urb->iso_frame_desc[i].status ||
+		    urb->iso_frame_desc[i].actual_length < 3)
+			continue;
+		f = combine_triple(cp) << 2;
+#if 0
+		if (f < subs->freqn - (subs->freqn>>3) || f > subs->freqmax) {
+			snd_printd(KERN_WARNING "requested frequency %d (%u,%03uHz) out of range (current nominal %d (%u,%03uHz))\n",
+				   f, f >> 14, (f & ((1 << 14) - 1) * 1000) / ((1 << 14) - 1),
+				   subs->freqn, subs->freqn >> 14, (subs->freqn & ((1 << 14) - 1) * 1000) / ((1 << 14) - 1));
+			continue;
+		}
+#endif
+		found = f;
+	}
+	if (found) {
+		spin_lock_irqsave(&subs->lock, flags);
+		subs->freqm = found;
+		spin_unlock_irqrestore(&subs->lock, flags);
+	}
+
+	return 0;
+}
+
+/*
+ * process after high speed playback sync complete
+ *
+ * retrieve the current 12.13 frequency from pipe, and set it.
+ * the value is referred in prepare_playback_urb().
+ */
+static int retire_playback_sync_urb_hs(snd_usb_substream_t *subs,
+				       snd_pcm_runtime_t *runtime,
+				       struct urb *urb)
+{
+	int i;
+	unsigned int found;
+	unsigned char *cp = urb->transfer_buffer;
+	unsigned long flags;
+
+	found = 0;
+	for (i = 0; i < urb->number_of_packets; i++, cp += 4) {
+		if (urb->iso_frame_desc[i].status ||
+		    urb->iso_frame_desc[i].actual_length < 4)
+			continue;
+		found = combine_quad(cp) & 0x0fffffff;
+	}
+	if (found) {
+		spin_lock_irqsave(&subs->lock, flags);
+		subs->freqm = found;
+		spin_unlock_irqrestore(&subs->lock, flags);
+	}
+
+	return 0;
+}
+
+/*
+ * prepare urb for playback data pipe
+ *
+ * we copy the data directly from the pcm buffer.
+ * the current position to be copied is held in hwptr field.
+ * since a urb can handle only a single linear buffer, if the total
+ * transferred area overflows the buffer boundary, we cannot send
+ * it directly from the buffer.  thus the data is once copied to
+ * a temporary buffer and urb points to that.
+ */
+static int prepare_playback_urb(snd_usb_substream_t *subs,
+				snd_pcm_runtime_t *runtime,
+				struct urb *urb)
+{
+	int i, stride, offs;
+	unsigned int counts;
+	unsigned long flags;
+	snd_urb_ctx_t *ctx = (snd_urb_ctx_t *)urb->context;
+
+	stride = runtime->frame_bits >> 3;
+
+	offs = 0;
+	urb->dev = ctx->subs->dev; /* we need to set this at each time */
+	urb->number_of_packets = 0;
+	spin_lock_irqsave(&subs->lock, flags);
+	for (i = 0; i < ctx->packets; i++) {
+		/* calculate the size of a packet */
+		if (subs->fill_max)
+			counts = subs->maxframesize; /* fixed */
+		else {
+			subs->phase = (subs->phase & 0xffff) + subs->freqm;
+			counts = subs->phase >> 16;
+			if (counts > subs->maxframesize)
+				counts = subs->maxframesize;
+		}
+		/* set up descriptor */
+		urb->iso_frame_desc[i].offset = offs * stride;
+		urb->iso_frame_desc[i].length = counts * stride;
+		offs += counts;
+		urb->number_of_packets++;
+		subs->transfer_sched += counts;
+		if (subs->transfer_sched >= runtime->period_size) {
+			subs->transfer_sched -= runtime->period_size;
+			if (subs->fmt_type == USB_FORMAT_TYPE_II) {
+				if (subs->transfer_sched > 0) {
+					/* FIXME: fill-max mode is not supported yet */
+					offs -= subs->transfer_sched;
+					counts -= subs->transfer_sched;
+					urb->iso_frame_desc[i].length = counts * stride;
+					subs->transfer_sched = 0;
+				}
+				i++;
+				if (i < ctx->packets) {
+					/* add a transfer delimiter */
+					urb->iso_frame_desc[i].offset = offs * stride;
+					urb->iso_frame_desc[i].length = 0;
+					urb->number_of_packets++;
+				}
+			}
+			break;
+ 		}
+	}
+	if (subs->hwptr + offs > runtime->buffer_size) {
+		/* err, the transferred area goes over buffer boundary.
+		 * copy the data to the temp buffer.
+		 */
+		int len;
+		len = runtime->buffer_size - subs->hwptr;
+		urb->transfer_buffer = subs->tmpbuf;
+		memcpy(subs->tmpbuf, runtime->dma_area + subs->hwptr * stride, len * stride);
+		memcpy(subs->tmpbuf + len * stride, runtime->dma_area, (offs - len) * stride);
+		subs->hwptr += offs;
+		subs->hwptr -= runtime->buffer_size;
+	} else {
+		/* set the buffer pointer */
+		urb->transfer_buffer = runtime->dma_area + subs->hwptr * stride;
+		subs->hwptr += offs;
+	}
+	spin_unlock_irqrestore(&subs->lock, flags);
+	urb->transfer_buffer_length = offs * stride;
+	ctx->transfer = offs;
+
+	return 0;
+}
+
+/*
+ * process after playback data complete
+ *
+ * update the current position and call callback if a period is processed.
+ */
+static int retire_playback_urb(snd_usb_substream_t *subs,
+			       snd_pcm_runtime_t *runtime,
+			       struct urb *urb)
+{
+	unsigned long flags;
+	snd_urb_ctx_t *ctx = (snd_urb_ctx_t *)urb->context;
+
+	spin_lock_irqsave(&subs->lock, flags);
+	subs->transfer_done += ctx->transfer;
+	subs->hwptr_done += ctx->transfer;
+	ctx->transfer = 0;
+	if (subs->hwptr_done >= runtime->buffer_size)
+		subs->hwptr_done -= runtime->buffer_size;
+	if (subs->transfer_done >= runtime->period_size) {
+		subs->transfer_done -= runtime->period_size;
+		spin_unlock_irqrestore(&subs->lock, flags);
+		snd_pcm_period_elapsed(subs->pcm_substream);
+	} else
+		spin_unlock_irqrestore(&subs->lock, flags);
+	return 0;
+}
+
+
+/*
+ */
+static struct snd_urb_ops audio_urb_ops[2] = {
+	{
+		.prepare =	prepare_playback_urb,
+		.retire =	retire_playback_urb,
+		.prepare_sync =	prepare_playback_sync_urb,
+		.retire_sync =	retire_playback_sync_urb,
+	},
+	{
+		.prepare =	prepare_capture_urb,
+		.retire =	retire_capture_urb,
+		.prepare_sync =	prepare_capture_sync_urb,
+		.retire_sync =	retire_capture_sync_urb,
+	},
+};
+
+static struct snd_urb_ops audio_urb_ops_high_speed[2] = {
+	{
+		.prepare =	prepare_playback_urb,
+		.retire =	retire_playback_urb,
+		.prepare_sync =	prepare_playback_sync_urb_hs,
+		.retire_sync =	retire_playback_sync_urb_hs,
+	},
+	{
+		.prepare =	prepare_capture_urb,
+		.retire =	retire_capture_urb,
+		.prepare_sync =	prepare_capture_sync_urb_hs,
+		.retire_sync =	retire_capture_sync_urb,
+	},
+};
+
+/*
+ * complete callback from data urb
+ */
+static void snd_complete_urb(struct urb *urb, struct pt_regs *regs)
+{
+	snd_urb_ctx_t *ctx = (snd_urb_ctx_t *)urb->context;
+	snd_usb_substream_t *subs = ctx->subs;
+	snd_pcm_substream_t *substream = ctx->subs->pcm_substream;
+	int err = 0;
+
+	if ((subs->running && subs->ops.retire(subs, substream->runtime, urb)) ||
+	    ! subs->running || /* can be stopped during retire callback */
+	    (err = subs->ops.prepare(subs, substream->runtime, urb)) < 0 ||
+	    (err = usb_submit_urb(urb, GFP_ATOMIC)) < 0) {
+		clear_bit(ctx->index, &subs->active_mask);
+		if (err < 0) {
+			snd_printd(KERN_ERR "cannot submit urb (err = %d)\n", err);
+			snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN);
+		}
+	}
+}
+
+
+/*
+ * complete callback from sync urb
+ */
+static void snd_complete_sync_urb(struct urb *urb, struct pt_regs *regs)
+{
+	snd_urb_ctx_t *ctx = (snd_urb_ctx_t *)urb->context;
+	snd_usb_substream_t *subs = ctx->subs;
+	snd_pcm_substream_t *substream = ctx->subs->pcm_substream;
+	int err = 0;
+
+	if ((subs->running && subs->ops.retire_sync(subs, substream->runtime, urb)) ||
+	    ! subs->running || /* can be stopped during retire callback */
+	    (err = subs->ops.prepare_sync(subs, substream->runtime, urb)) < 0 ||
+	    (err = usb_submit_urb(urb, GFP_ATOMIC)) < 0) {
+		clear_bit(ctx->index + 16, &subs->active_mask);
+		if (err < 0) {
+			snd_printd(KERN_ERR "cannot submit sync urb (err = %d)\n", err);
+			snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN);
+		}
+	}
+}
+
+
+/*
+ * unlink active urbs.
+ */
+static int deactivate_urbs(snd_usb_substream_t *subs, int force, int can_sleep)
+{
+	unsigned int i;
+	int async;
+
+	subs->running = 0;
+
+	if (!force && subs->stream->chip->shutdown) /* to be sure... */
+		return -EBADFD;
+
+	async = !can_sleep && async_unlink;
+
+	if (! async && in_interrupt())
+		return 0;
+
+	for (i = 0; i < subs->nurbs; i++) {
+		if (test_bit(i, &subs->active_mask)) {
+			if (! test_and_set_bit(i, &subs->unlink_mask)) {
+				struct urb *u = subs->dataurb[i].urb;
+				if (async) {
+					u->transfer_flags |= URB_ASYNC_UNLINK;
+					usb_unlink_urb(u);
+				} else
+					usb_kill_urb(u);
+			}
+		}
+	}
+	if (subs->syncpipe) {
+		for (i = 0; i < SYNC_URBS; i++) {
+			if (test_bit(i+16, &subs->active_mask)) {
+ 				if (! test_and_set_bit(i+16, &subs->unlink_mask)) {
+					struct urb *u = subs->syncurb[i].urb;
+					if (async) {
+						u->transfer_flags |= URB_ASYNC_UNLINK;
+						usb_unlink_urb(u);
+					} else
+						usb_kill_urb(u);
+				}
+			}
+		}
+	}
+	return 0;
+}
+
+
+/*
+ * set up and start data/sync urbs
+ */
+static int start_urbs(snd_usb_substream_t *subs, snd_pcm_runtime_t *runtime)
+{
+	unsigned int i;
+	int err;
+
+	if (subs->stream->chip->shutdown)
+		return -EBADFD;
+
+	for (i = 0; i < subs->nurbs; i++) {
+		snd_assert(subs->dataurb[i].urb, return -EINVAL);
+		if (subs->ops.prepare(subs, runtime, subs->dataurb[i].urb) < 0) {
+			snd_printk(KERN_ERR "cannot prepare datapipe for urb %d\n", i);
+			goto __error;
+		}
+	}
+	if (subs->syncpipe) {
+		for (i = 0; i < SYNC_URBS; i++) {
+			snd_assert(subs->syncurb[i].urb, return -EINVAL);
+			if (subs->ops.prepare_sync(subs, runtime, subs->syncurb[i].urb) < 0) {
+				snd_printk(KERN_ERR "cannot prepare syncpipe for urb %d\n", i);
+				goto __error;
+			}
+		}
+	}
+
+	subs->active_mask = 0;
+	subs->unlink_mask = 0;
+	subs->running = 1;
+	for (i = 0; i < subs->nurbs; i++) {
+		if ((err = usb_submit_urb(subs->dataurb[i].urb, GFP_ATOMIC)) < 0) {
+			snd_printk(KERN_ERR "cannot submit datapipe for urb %d, err = %d\n", i, err);
+			goto __error;
+		}
+		set_bit(i, &subs->active_mask);
+	}
+	if (subs->syncpipe) {
+		for (i = 0; i < SYNC_URBS; i++) {
+			if ((err = usb_submit_urb(subs->syncurb[i].urb, GFP_ATOMIC)) < 0) {
+				snd_printk(KERN_ERR "cannot submit syncpipe for urb %d, err = %d\n", i, err);
+				goto __error;
+			}
+			set_bit(i + 16, &subs->active_mask);
+		}
+	}
+	return 0;
+
+ __error:
+	// snd_pcm_stop(subs->pcm_substream, SNDRV_PCM_STATE_XRUN);
+	deactivate_urbs(subs, 0, 0);
+	return -EPIPE;
+}
+
+
+/*
+ *  wait until all urbs are processed.
+ */
+static int wait_clear_urbs(snd_usb_substream_t *subs)
+{
+	int timeout = HZ;
+	unsigned int i;
+	int alive;
+
+	do {
+		alive = 0;
+		for (i = 0; i < subs->nurbs; i++) {
+			if (test_bit(i, &subs->active_mask))
+				alive++;
+		}
+		if (subs->syncpipe) {
+			for (i = 0; i < SYNC_URBS; i++) {
+				if (test_bit(i + 16, &subs->active_mask))
+					alive++;
+			}
+		}
+		if (! alive)
+			break;
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		schedule_timeout(1);
+	} while (--timeout > 0);
+	if (alive)
+		snd_printk(KERN_ERR "timeout: still %d active urbs..\n", alive);
+	return 0;
+}
+
+
+/*
+ * return the current pcm pointer.  just return the hwptr_done value.
+ */
+static snd_pcm_uframes_t snd_usb_pcm_pointer(snd_pcm_substream_t *substream)
+{
+	snd_usb_substream_t *subs = (snd_usb_substream_t *)substream->runtime->private_data;
+	return subs->hwptr_done;
+}
+
+
+/*
+ * start/stop substream
+ */
+static int snd_usb_pcm_trigger(snd_pcm_substream_t *substream, int cmd)
+{
+	snd_usb_substream_t *subs = (snd_usb_substream_t *)substream->runtime->private_data;
+	int err;
+
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_START:
+		err = start_urbs(subs, substream->runtime);
+		break;
+	case SNDRV_PCM_TRIGGER_STOP:
+		err = deactivate_urbs(subs, 0, 0);
+		break;
+	default:
+		err = -EINVAL;
+		break;
+	}
+	return err < 0 ? err : 0;
+}
+
+
+/*
+ * release a urb data
+ */
+static void release_urb_ctx(snd_urb_ctx_t *u)
+{
+	if (u->urb) {
+		usb_free_urb(u->urb);
+		u->urb = NULL;
+	}
+	if (u->buf) {
+		kfree(u->buf);
+		u->buf = NULL;
+	}
+}
+
+/*
+ * release a substream
+ */
+static void release_substream_urbs(snd_usb_substream_t *subs, int force)
+{
+	int i;
+
+	/* stop urbs (to be sure) */
+	deactivate_urbs(subs, force, 1);
+	wait_clear_urbs(subs);
+
+	for (i = 0; i < MAX_URBS; i++)
+		release_urb_ctx(&subs->dataurb[i]);
+	for (i = 0; i < SYNC_URBS; i++)
+		release_urb_ctx(&subs->syncurb[i]);
+	if (subs->tmpbuf) {
+		kfree(subs->tmpbuf);
+		subs->tmpbuf = NULL;
+	}
+	subs->nurbs = 0;
+}
+
+/*
+ * initialize a substream for plaback/capture
+ */
+static int init_substream_urbs(snd_usb_substream_t *subs, unsigned int period_bytes,
+			       unsigned int rate, unsigned int frame_bits)
+{
+	unsigned int maxsize, n, i;
+	int is_playback = subs->direction == SNDRV_PCM_STREAM_PLAYBACK;
+	unsigned int npacks[MAX_URBS], urb_packs, total_packs;
+
+	/* calculate the frequency in 16.16 format */
+	if (snd_usb_get_speed(subs->dev) == USB_SPEED_FULL)
+		subs->freqn = get_usb_full_speed_rate(rate);
+	else
+		subs->freqn = get_usb_high_speed_rate(rate);
+	subs->freqm = subs->freqn;
+	subs->freqmax = subs->freqn + (subs->freqn >> 2); /* max. allowed frequency */
+	subs->phase = 0;
+
+	/* calculate the max. size of packet */
+	maxsize = ((subs->freqmax + 0xffff) * (frame_bits >> 3)) >> 16;
+	if (subs->maxpacksize && maxsize > subs->maxpacksize) {
+		//snd_printd(KERN_DEBUG "maxsize %d is greater than defined size %d\n",
+		//	   maxsize, subs->maxpacksize);
+		maxsize = subs->maxpacksize;
+	}
+
+	if (subs->fill_max)
+		subs->curpacksize = subs->maxpacksize;
+	else
+		subs->curpacksize = maxsize;
+
+	if (snd_usb_get_speed(subs->dev) == USB_SPEED_FULL)
+		urb_packs = nrpacks;
+	else
+		urb_packs = nrpacks * 8;
+
+	/* allocate a temporary buffer for playback */
+	if (is_playback) {
+		subs->tmpbuf = kmalloc(maxsize * urb_packs, GFP_KERNEL);
+		if (! subs->tmpbuf) {
+			snd_printk(KERN_ERR "cannot malloc tmpbuf\n");
+			return -ENOMEM;
+		}
+	}
+
+	/* decide how many packets to be used */
+	total_packs = (period_bytes + maxsize - 1) / maxsize;
+	if (total_packs < 2 * MIN_PACKS_URB)
+		total_packs = 2 * MIN_PACKS_URB;
+	subs->nurbs = (total_packs + urb_packs - 1) / urb_packs;
+	if (subs->nurbs > MAX_URBS) {
+		/* too much... */
+		subs->nurbs = MAX_URBS;
+		total_packs = MAX_URBS * urb_packs;
+	}
+	n = total_packs;
+	for (i = 0; i < subs->nurbs; i++) {
+		npacks[i] = n > urb_packs ? urb_packs : n;
+		n -= urb_packs;
+	}
+	if (subs->nurbs <= 1) {
+		/* too little - we need at least two packets
+		 * to ensure contiguous playback/capture
+		 */
+		subs->nurbs = 2;
+		npacks[0] = (total_packs + 1) / 2;
+		npacks[1] = total_packs - npacks[0];
+	} else if (npacks[subs->nurbs-1] < MIN_PACKS_URB) {
+		/* the last packet is too small.. */
+		if (subs->nurbs > 2) {
+			/* merge to the first one */
+			npacks[0] += npacks[subs->nurbs - 1];
+			subs->nurbs--;
+		} else {
+			/* divide to two */
+			subs->nurbs = 2;
+			npacks[0] = (total_packs + 1) / 2;
+			npacks[1] = total_packs - npacks[0];
+		}
+	}
+
+	/* allocate and initialize data urbs */
+	for (i = 0; i < subs->nurbs; i++) {
+		snd_urb_ctx_t *u = &subs->dataurb[i];
+		u->index = i;
+		u->subs = subs;
+		u->transfer = 0;
+		u->packets = npacks[i];
+		if (subs->fmt_type == USB_FORMAT_TYPE_II)
+			u->packets++; /* for transfer delimiter */
+		if (! is_playback) {
+			/* allocate a capture buffer per urb */
+			u->buf = kmalloc(maxsize * u->packets, GFP_KERNEL);
+			if (! u->buf) {
+				release_substream_urbs(subs, 0);
+				return -ENOMEM;
+			}
+		}
+		u->urb = usb_alloc_urb(u->packets, GFP_KERNEL);
+		if (! u->urb) {
+			release_substream_urbs(subs, 0);
+			return -ENOMEM;
+		}
+		u->urb->dev = subs->dev;
+		u->urb->pipe = subs->datapipe;
+		u->urb->transfer_flags = URB_ISO_ASAP;
+		u->urb->number_of_packets = u->packets;
+		u->urb->interval = 1;
+		u->urb->context = u;
+		u->urb->complete = snd_usb_complete_callback(snd_complete_urb);
+	}
+
+	if (subs->syncpipe) {
+		/* allocate and initialize sync urbs */
+		for (i = 0; i < SYNC_URBS; i++) {
+			snd_urb_ctx_t *u = &subs->syncurb[i];
+			u->index = i;
+			u->subs = subs;
+			u->packets = nrpacks;
+			u->urb = usb_alloc_urb(u->packets, GFP_KERNEL);
+			if (! u->urb) {
+				release_substream_urbs(subs, 0);
+				return -ENOMEM;
+			}
+			u->urb->transfer_buffer = subs->syncbuf + i * nrpacks * 4;
+			u->urb->transfer_buffer_length = nrpacks * 4;
+			u->urb->dev = subs->dev;
+			u->urb->pipe = subs->syncpipe;
+			u->urb->transfer_flags = URB_ISO_ASAP;
+			u->urb->number_of_packets = u->packets;
+			if (snd_usb_get_speed(subs->dev) == USB_SPEED_HIGH)
+				u->urb->interval = 8;
+			else
+				u->urb->interval = 1;
+			u->urb->context = u;
+			u->urb->complete = snd_usb_complete_callback(snd_complete_sync_urb);
+		}
+	}
+	return 0;
+}
+
+
+/*
+ * find a matching audio format
+ */
+static struct audioformat *find_format(snd_usb_substream_t *subs, unsigned int format,
+				       unsigned int rate, unsigned int channels)
+{
+	struct list_head *p;
+	struct audioformat *found = NULL;
+	int cur_attr = 0, attr;
+
+	list_for_each(p, &subs->fmt_list) {
+		struct audioformat *fp;
+		fp = list_entry(p, struct audioformat, list);
+		if (fp->format != format || fp->channels != channels)
+			continue;
+		if (rate < fp->rate_min || rate > fp->rate_max)
+			continue;
+		if (! (fp->rates & SNDRV_PCM_RATE_CONTINUOUS)) {
+			unsigned int i;
+			for (i = 0; i < fp->nr_rates; i++)
+				if (fp->rate_table[i] == rate)
+					break;
+			if (i >= fp->nr_rates)
+				continue;
+		}
+		attr = fp->ep_attr & EP_ATTR_MASK;
+		if (! found) {
+			found = fp;
+			cur_attr = attr;
+			continue;
+		}
+		/* avoid async out and adaptive in if the other method
+		 * supports the same format.
+		 * this is a workaround for the case like
+		 * M-audio audiophile USB.
+		 */
+		if (attr != cur_attr) {
+			if ((attr == EP_ATTR_ASYNC &&
+			     subs->direction == SNDRV_PCM_STREAM_PLAYBACK) ||
+			    (attr == EP_ATTR_ADAPTIVE &&
+			     subs->direction == SNDRV_PCM_STREAM_CAPTURE))
+				continue;
+			if ((cur_attr == EP_ATTR_ASYNC &&
+			     subs->direction == SNDRV_PCM_STREAM_PLAYBACK) ||
+			    (cur_attr == EP_ATTR_ADAPTIVE &&
+			     subs->direction == SNDRV_PCM_STREAM_CAPTURE)) {
+				found = fp;
+				cur_attr = attr;
+				continue;
+			}
+		}
+		/* find the format with the largest max. packet size */
+		if (fp->maxpacksize > found->maxpacksize) {
+			found = fp;
+			cur_attr = attr;
+		}
+	}
+	return found;
+}
+
+
+/*
+ * initialize the picth control and sample rate
+ */
+static int init_usb_pitch(struct usb_device *dev, int iface,
+			  struct usb_host_interface *alts,
+			  struct audioformat *fmt)
+{
+	unsigned int ep;
+	unsigned char data[1];
+	int err;
+
+	ep = get_endpoint(alts, 0)->bEndpointAddress;
+	/* if endpoint has pitch control, enable it */
+	if (fmt->attributes & EP_CS_ATTR_PITCH_CONTROL) {
+		data[0] = 1;
+		if ((err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), SET_CUR,
+					   USB_TYPE_CLASS|USB_RECIP_ENDPOINT|USB_DIR_OUT,
+					   PITCH_CONTROL << 8, ep, data, 1, 1000)) < 0) {
+			snd_printk(KERN_ERR "%d:%d:%d: cannot set enable PITCH\n",
+				   dev->devnum, iface, ep);
+			return err;
+		}
+	}
+	return 0;
+}
+
+static int init_usb_sample_rate(struct usb_device *dev, int iface,
+				struct usb_host_interface *alts,
+				struct audioformat *fmt, int rate)
+{
+	unsigned int ep;
+	unsigned char data[3];
+	int err;
+
+	ep = get_endpoint(alts, 0)->bEndpointAddress;
+	/* if endpoint has sampling rate control, set it */
+	if (fmt->attributes & EP_CS_ATTR_SAMPLE_RATE) {
+		int crate;
+		data[0] = rate;
+		data[1] = rate >> 8;
+		data[2] = rate >> 16;
+		if ((err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), SET_CUR,
+					   USB_TYPE_CLASS|USB_RECIP_ENDPOINT|USB_DIR_OUT,
+					   SAMPLING_FREQ_CONTROL << 8, ep, data, 3, 1000)) < 0) {
+			snd_printk(KERN_ERR "%d:%d:%d: cannot set freq %d to ep 0x%x\n",
+				   dev->devnum, iface, fmt->altsetting, rate, ep);
+			return err;
+		}
+		if ((err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), GET_CUR,
+					   USB_TYPE_CLASS|USB_RECIP_ENDPOINT|USB_DIR_IN,
+					   SAMPLING_FREQ_CONTROL << 8, ep, data, 3, 1000)) < 0) {
+			snd_printk(KERN_WARNING "%d:%d:%d: cannot get freq at ep 0x%x\n",
+				   dev->devnum, iface, fmt->altsetting, ep);
+			return 0; /* some devices don't support reading */
+		}
+		crate = data[0] | (data[1] << 8) | (data[2] << 16);
+		if (crate != rate) {
+			snd_printd(KERN_WARNING "current rate %d is different from the runtime rate %d\n", crate, rate);
+			// runtime->rate = crate;
+		}
+	}
+	return 0;
+}
+
+/*
+ * find a matching format and set up the interface
+ */
+static int set_format(snd_usb_substream_t *subs, struct audioformat *fmt)
+{
+	struct usb_device *dev = subs->dev;
+	struct usb_host_interface *alts;
+	struct usb_interface_descriptor *altsd;
+	struct usb_interface *iface;
+	unsigned int ep, attr;
+	int is_playback = subs->direction == SNDRV_PCM_STREAM_PLAYBACK;
+	int err;
+
+	iface = usb_ifnum_to_if(dev, fmt->iface);
+	snd_assert(iface, return -EINVAL);
+	alts = &iface->altsetting[fmt->altset_idx];
+	altsd = get_iface_desc(alts);
+	snd_assert(altsd->bAlternateSetting == fmt->altsetting, return -EINVAL);
+
+	if (fmt == subs->cur_audiofmt)
+		return 0;
+
+	/* close the old interface */
+	if (subs->interface >= 0 && subs->interface != fmt->iface) {
+		usb_set_interface(subs->dev, subs->interface, 0);
+		subs->interface = -1;
+		subs->format = 0;
+	}
+
+	/* set interface */
+	if (subs->interface != fmt->iface || subs->format != fmt->altset_idx) {
+		if (usb_set_interface(dev, fmt->iface, fmt->altsetting) < 0) {
+			snd_printk(KERN_ERR "%d:%d:%d: usb_set_interface failed\n",
+				   dev->devnum, fmt->iface, fmt->altsetting);
+			return -EIO;
+		}
+		snd_printdd(KERN_INFO "setting usb interface %d:%d\n", fmt->iface, fmt->altsetting);
+		subs->interface = fmt->iface;
+		subs->format = fmt->altset_idx;
+	}
+
+	/* create a data pipe */
+	ep = fmt->endpoint & USB_ENDPOINT_NUMBER_MASK;
+	if (is_playback)
+		subs->datapipe = usb_sndisocpipe(dev, ep);
+	else
+		subs->datapipe = usb_rcvisocpipe(dev, ep);
+	subs->syncpipe = subs->syncinterval = 0;
+	subs->maxpacksize = fmt->maxpacksize;
+	subs->fill_max = 0;
+
+	/* we need a sync pipe in async OUT or adaptive IN mode */
+	/* check the number of EP, since some devices have broken
+	 * descriptors which fool us.  if it has only one EP,
+	 * assume it as adaptive-out or sync-in.
+	 */
+	attr = fmt->ep_attr & EP_ATTR_MASK;
+	if (((is_playback && attr == EP_ATTR_ASYNC) ||
+	     (! is_playback && attr == EP_ATTR_ADAPTIVE)) &&
+	    altsd->bNumEndpoints >= 2) {
+		/* check sync-pipe endpoint */
+		/* ... and check descriptor size before accessing bSynchAddress
+		   because there is a version of the SB Audigy 2 NX firmware lacking
+		   the audio fields in the endpoint descriptors */
+		if ((get_endpoint(alts, 1)->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) != 0x01 ||
+		    (get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
+		     get_endpoint(alts, 1)->bSynchAddress != 0)) {
+			snd_printk(KERN_ERR "%d:%d:%d : invalid synch pipe\n",
+				   dev->devnum, fmt->iface, fmt->altsetting);
+			return -EINVAL;
+		}
+		ep = get_endpoint(alts, 1)->bEndpointAddress;
+		if (get_endpoint(alts, 0)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
+		    (( is_playback && ep != (unsigned int)(get_endpoint(alts, 0)->bSynchAddress | USB_DIR_IN)) ||
+		     (!is_playback && ep != (unsigned int)(get_endpoint(alts, 0)->bSynchAddress & ~USB_DIR_IN)))) {
+			snd_printk(KERN_ERR "%d:%d:%d : invalid synch pipe\n",
+				   dev->devnum, fmt->iface, fmt->altsetting);
+			return -EINVAL;
+		}
+		ep &= USB_ENDPOINT_NUMBER_MASK;
+		if (is_playback)
+			subs->syncpipe = usb_rcvisocpipe(dev, ep);
+		else
+			subs->syncpipe = usb_sndisocpipe(dev, ep);
+		subs->syncinterval = get_endpoint(alts, 1)->bRefresh;
+	}
+
+	/* always fill max packet size */
+	if (fmt->attributes & EP_CS_ATTR_FILL_MAX)
+		subs->fill_max = 1;
+
+	if ((err = init_usb_pitch(dev, subs->interface, alts, fmt)) < 0)
+		return err;
+
+	subs->cur_audiofmt = fmt;
+
+#if 0
+	printk("setting done: format = %d, rate = %d, channels = %d\n",
+	       fmt->format, fmt->rate, fmt->channels);
+	printk("  datapipe = 0x%0x, syncpipe = 0x%0x\n",
+	       subs->datapipe, subs->syncpipe);
+#endif
+
+	return 0;
+}
+
+/*
+ * hw_params callback
+ *
+ * allocate a buffer and set the given audio format.
+ *
+ * so far we use a physically linear buffer although packetize transfer
+ * doesn't need a continuous area.
+ * if sg buffer is supported on the later version of alsa, we'll follow
+ * that.
+ */
+static int snd_usb_hw_params(snd_pcm_substream_t *substream,
+			     snd_pcm_hw_params_t *hw_params)
+{
+	snd_usb_substream_t *subs = (snd_usb_substream_t *)substream->runtime->private_data;
+	struct audioformat *fmt;
+	unsigned int channels, rate, format;
+	int ret, changed;
+
+	ret = snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(hw_params));
+	if (ret < 0)
+		return ret;
+
+	format = params_format(hw_params);
+	rate = params_rate(hw_params);
+	channels = params_channels(hw_params);
+	fmt = find_format(subs, format, rate, channels);
+	if (! fmt) {
+		snd_printd(KERN_DEBUG "cannot set format: format = %s, rate = %d, channels = %d\n",
+			   snd_pcm_format_name(format), rate, channels);
+		return -EINVAL;
+	}
+
+	changed = subs->cur_audiofmt != fmt ||
+		subs->period_bytes != params_period_bytes(hw_params) ||
+		subs->cur_rate != rate;
+	if ((ret = set_format(subs, fmt)) < 0)
+		return ret;
+
+	if (subs->cur_rate != rate) {
+		struct usb_host_interface *alts;
+		struct usb_interface *iface;
+		iface = usb_ifnum_to_if(subs->dev, fmt->iface);
+		alts = &iface->altsetting[fmt->altset_idx];
+		ret = init_usb_sample_rate(subs->dev, subs->interface, alts, fmt, rate);
+		if (ret < 0)
+			return ret;
+		subs->cur_rate = rate;
+	}
+
+	if (changed) {
+		/* format changed */
+		release_substream_urbs(subs, 0);
+		/* influenced: period_bytes, channels, rate, format, */
+		ret = init_substream_urbs(subs, params_period_bytes(hw_params),
+					  params_rate(hw_params),
+					  snd_pcm_format_physical_width(params_format(hw_params)) * params_channels(hw_params));
+	}
+
+	return ret;
+}
+
+/*
+ * hw_free callback
+ *
+ * reset the audio format and release the buffer
+ */
+static int snd_usb_hw_free(snd_pcm_substream_t *substream)
+{
+	snd_usb_substream_t *subs = (snd_usb_substream_t *)substream->runtime->private_data;
+
+	subs->cur_audiofmt = NULL;
+	subs->cur_rate = 0;
+	subs->period_bytes = 0;
+	release_substream_urbs(subs, 0);
+	return snd_pcm_lib_free_pages(substream);
+}
+
+/*
+ * prepare callback
+ *
+ * only a few subtle things...
+ */
+static int snd_usb_pcm_prepare(snd_pcm_substream_t *substream)
+{
+	snd_pcm_runtime_t *runtime = substream->runtime;
+	snd_usb_substream_t *subs = (snd_usb_substream_t *)runtime->private_data;
+
+	if (! subs->cur_audiofmt) {
+		snd_printk(KERN_ERR "usbaudio: no format is specified!\n");
+		return -ENXIO;
+	}
+
+	/* some unit conversions in runtime */
+	subs->maxframesize = bytes_to_frames(runtime, subs->maxpacksize);
+	subs->curframesize = bytes_to_frames(runtime, subs->curpacksize);
+
+	/* reset the pointer */
+	subs->hwptr = 0;
+	subs->hwptr_done = 0;
+	subs->transfer_sched = 0;
+	subs->transfer_done = 0;
+	subs->phase = 0;
+
+	/* clear urbs (to be sure) */
+	deactivate_urbs(subs, 0, 1);
+	wait_clear_urbs(subs);
+
+	return 0;
+}
+
+static snd_pcm_hardware_t snd_usb_playback =
+{
+	.info =			(SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_INTERLEAVED |
+				 SNDRV_PCM_INFO_BLOCK_TRANSFER |
+				 SNDRV_PCM_INFO_MMAP_VALID),
+	.buffer_bytes_max =	(128*1024),
+	.period_bytes_min =	64,
+	.period_bytes_max =	(128*1024),
+	.periods_min =		2,
+	.periods_max =		1024,
+};
+
+static snd_pcm_hardware_t snd_usb_capture =
+{
+	.info =			(SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_INTERLEAVED |
+				 SNDRV_PCM_INFO_BLOCK_TRANSFER |
+				 SNDRV_PCM_INFO_MMAP_VALID),
+	.buffer_bytes_max =	(128*1024),
+	.period_bytes_min =	64,
+	.period_bytes_max =	(128*1024),
+	.periods_min =		2,
+	.periods_max =		1024,
+};
+
+/*
+ * h/w constraints
+ */
+
+#ifdef HW_CONST_DEBUG
+#define hwc_debug(fmt, args...) printk(KERN_DEBUG fmt, ##args)
+#else
+#define hwc_debug(fmt, args...) /**/
+#endif
+
+static int hw_check_valid_format(snd_pcm_hw_params_t *params, struct audioformat *fp)
+{
+	snd_interval_t *it = hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
+	snd_interval_t *ct = hw_param_interval(params, SNDRV_PCM_HW_PARAM_CHANNELS);
+	snd_mask_t *fmts = hw_param_mask(params, SNDRV_PCM_HW_PARAM_FORMAT);
+
+	/* check the format */
+	if (! snd_mask_test(fmts, fp->format)) {
+		hwc_debug("   > check: no supported format %d\n", fp->format);
+		return 0;
+	}
+	/* check the channels */
+	if (fp->channels < ct->min || fp->channels > ct->max) {
+		hwc_debug("   > check: no valid channels %d (%d/%d)\n", fp->channels, ct->min, ct->max);
+		return 0;
+	}
+	/* check the rate is within the range */
+	if (fp->rate_min > it->max || (fp->rate_min == it->max && it->openmax)) {
+		hwc_debug("   > check: rate_min %d > max %d\n", fp->rate_min, it->max);
+		return 0;
+	}
+	if (fp->rate_max < it->min || (fp->rate_max == it->min && it->openmin)) {
+		hwc_debug("   > check: rate_max %d < min %d\n", fp->rate_max, it->min);
+		return 0;
+	}
+	return 1;
+}
+
+static int hw_rule_rate(snd_pcm_hw_params_t *params,
+			snd_pcm_hw_rule_t *rule)
+{
+	snd_usb_substream_t *subs = rule->private;
+	struct list_head *p;
+	snd_interval_t *it = hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
+	unsigned int rmin, rmax;
+	int changed;
+
+	hwc_debug("hw_rule_rate: (%d,%d)\n", it->min, it->max);
+	changed = 0;
+	rmin = rmax = 0;
+	list_for_each(p, &subs->fmt_list) {
+		struct audioformat *fp;
+		fp = list_entry(p, struct audioformat, list);
+		if (! hw_check_valid_format(params, fp))
+			continue;
+		if (changed++) {
+			if (rmin > fp->rate_min)
+				rmin = fp->rate_min;
+			if (rmax < fp->rate_max)
+				rmax = fp->rate_max;
+		} else {
+			rmin = fp->rate_min;
+			rmax = fp->rate_max;
+		}
+	}
+
+	if (! changed) {
+		hwc_debug("  --> get empty\n");
+		it->empty = 1;
+		return -EINVAL;
+	}
+
+	changed = 0;
+	if (it->min < rmin) {
+		it->min = rmin;
+		it->openmin = 0;
+		changed = 1;
+	}
+	if (it->max > rmax) {
+		it->max = rmax;
+		it->openmax = 0;
+		changed = 1;
+	}
+	if (snd_interval_checkempty(it)) {
+		it->empty = 1;
+		return -EINVAL;
+	}
+	hwc_debug("  --> (%d, %d) (changed = %d)\n", it->min, it->max, changed);
+	return changed;
+}
+
+
+static int hw_rule_channels(snd_pcm_hw_params_t *params,
+			    snd_pcm_hw_rule_t *rule)
+{
+	snd_usb_substream_t *subs = rule->private;
+	struct list_head *p;
+	snd_interval_t *it = hw_param_interval(params, SNDRV_PCM_HW_PARAM_CHANNELS);
+	unsigned int rmin, rmax;
+	int changed;
+
+	hwc_debug("hw_rule_channels: (%d,%d)\n", it->min, it->max);
+	changed = 0;
+	rmin = rmax = 0;
+	list_for_each(p, &subs->fmt_list) {
+		struct audioformat *fp;
+		fp = list_entry(p, struct audioformat, list);
+		if (! hw_check_valid_format(params, fp))
+			continue;
+		if (changed++) {
+			if (rmin > fp->channels)
+				rmin = fp->channels;
+			if (rmax < fp->channels)
+				rmax = fp->channels;
+		} else {
+			rmin = fp->channels;
+			rmax = fp->channels;
+		}
+	}
+
+	if (! changed) {
+		hwc_debug("  --> get empty\n");
+		it->empty = 1;
+		return -EINVAL;
+	}
+
+	changed = 0;
+	if (it->min < rmin) {
+		it->min = rmin;
+		it->openmin = 0;
+		changed = 1;
+	}
+	if (it->max > rmax) {
+		it->max = rmax;
+		it->openmax = 0;
+		changed = 1;
+	}
+	if (snd_interval_checkempty(it)) {
+		it->empty = 1;
+		return -EINVAL;
+	}
+	hwc_debug("  --> (%d, %d) (changed = %d)\n", it->min, it->max, changed);
+	return changed;
+}
+
+static int hw_rule_format(snd_pcm_hw_params_t *params,
+			  snd_pcm_hw_rule_t *rule)
+{
+	snd_usb_substream_t *subs = rule->private;
+	struct list_head *p;
+	snd_mask_t *fmt = hw_param_mask(params, SNDRV_PCM_HW_PARAM_FORMAT);
+	u64 fbits;
+	u32 oldbits[2];
+	int changed;
+
+	hwc_debug("hw_rule_format: %x:%x\n", fmt->bits[0], fmt->bits[1]);
+	fbits = 0;
+	list_for_each(p, &subs->fmt_list) {
+		struct audioformat *fp;
+		fp = list_entry(p, struct audioformat, list);
+		if (! hw_check_valid_format(params, fp))
+			continue;
+		fbits |= (1ULL << fp->format);
+	}
+
+	oldbits[0] = fmt->bits[0];
+	oldbits[1] = fmt->bits[1];
+	fmt->bits[0] &= (u32)fbits;
+	fmt->bits[1] &= (u32)(fbits >> 32);
+	if (! fmt->bits[0] && ! fmt->bits[1]) {
+		hwc_debug("  --> get empty\n");
+		return -EINVAL;
+	}
+	changed = (oldbits[0] != fmt->bits[0] || oldbits[1] != fmt->bits[1]);
+	hwc_debug("  --> %x:%x (changed = %d)\n", fmt->bits[0], fmt->bits[1], changed);
+	return changed;
+}
+
+#define MAX_MASK	64
+
+/*
+ * check whether the registered audio formats need special hw-constraints
+ */
+static int check_hw_params_convention(snd_usb_substream_t *subs)
+{
+	int i;
+	u32 *channels;
+	u32 *rates;
+	u32 cmaster, rmaster;
+	u32 rate_min = 0, rate_max = 0;
+	struct list_head *p;
+	int err = 1;
+
+	channels = kcalloc(MAX_MASK, sizeof(u32), GFP_KERNEL);
+	rates = kcalloc(MAX_MASK, sizeof(u32), GFP_KERNEL);
+
+	list_for_each(p, &subs->fmt_list) {
+		struct audioformat *f;
+		f = list_entry(p, struct audioformat, list);
+		/* unconventional channels? */
+		if (f->channels > 32)
+			goto __out;
+		/* continuous rate min/max matches? */
+		if (f->rates & SNDRV_PCM_RATE_CONTINUOUS) {
+			if (rate_min && f->rate_min != rate_min)
+				goto __out;
+			if (rate_max && f->rate_max != rate_max)
+				goto __out;
+			rate_min = f->rate_min;
+			rate_max = f->rate_max;
+		}
+		/* combination of continuous rates and fixed rates? */
+		if (rates[f->format] & SNDRV_PCM_RATE_CONTINUOUS) {
+			if (f->rates != rates[f->format])
+				goto __out;
+		}
+		if (f->rates & SNDRV_PCM_RATE_CONTINUOUS) {
+			if (rates[f->format] && rates[f->format] != f->rates)
+				goto __out;
+		}
+		channels[f->format] |= (1 << f->channels);
+		rates[f->format] |= f->rates;
+	}
+	/* check whether channels and rates match for all formats */
+	cmaster = rmaster = 0;
+	for (i = 0; i < MAX_MASK; i++) {
+		if (cmaster != channels[i] && cmaster && channels[i])
+			goto __out;
+		if (rmaster != rates[i] && rmaster && rates[i])
+			goto __out;
+		if (channels[i])
+			cmaster = channels[i];
+		if (rates[i])
+			rmaster = rates[i];
+	}
+	/* check whether channels match for all distinct rates */
+	memset(channels, 0, MAX_MASK * sizeof(u32));
+	list_for_each(p, &subs->fmt_list) {
+		struct audioformat *f;
+		f = list_entry(p, struct audioformat, list);
+		if (f->rates & SNDRV_PCM_RATE_CONTINUOUS)
+			continue;
+		for (i = 0; i < 32; i++) {
+			if (f->rates & (1 << i))
+				channels[i] |= (1 << f->channels);
+		}
+	}
+	cmaster = 0;
+	for (i = 0; i < 32; i++) {
+		if (cmaster != channels[i] && cmaster && channels[i])
+			goto __out;
+		if (channels[i])
+			cmaster = channels[i];
+	}
+	err = 0;
+
+ __out:
+	kfree(channels);
+	kfree(rates);
+	return err;
+}
+
+
+/*
+ * set up the runtime hardware information.
+ */
+
+static int setup_hw_info(snd_pcm_runtime_t *runtime, snd_usb_substream_t *subs)
+{
+	struct list_head *p;
+	int err;
+
+	runtime->hw.formats = subs->formats;
+
+	runtime->hw.rate_min = 0x7fffffff;
+	runtime->hw.rate_max = 0;
+	runtime->hw.channels_min = 256;
+	runtime->hw.channels_max = 0;
+	runtime->hw.rates = 0;
+	/* check min/max rates and channels */
+	list_for_each(p, &subs->fmt_list) {
+		struct audioformat *fp;
+		fp = list_entry(p, struct audioformat, list);
+		runtime->hw.rates |= fp->rates;
+		if (runtime->hw.rate_min > fp->rate_min)
+			runtime->hw.rate_min = fp->rate_min;
+		if (runtime->hw.rate_max < fp->rate_max)
+			runtime->hw.rate_max = fp->rate_max;
+		if (runtime->hw.channels_min > fp->channels)
+			runtime->hw.channels_min = fp->channels;
+		if (runtime->hw.channels_max < fp->channels)
+			runtime->hw.channels_max = fp->channels;
+		if (fp->fmt_type == USB_FORMAT_TYPE_II && fp->frame_size > 0) {
+			/* FIXME: there might be more than one audio formats... */
+			runtime->hw.period_bytes_min = runtime->hw.period_bytes_max =
+				fp->frame_size;
+		}
+	}
+
+	/* set the period time minimum 1ms */
+	snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_PERIOD_TIME,
+				     1000 * MIN_PACKS_URB,
+				     /*(nrpacks * MAX_URBS) * 1000*/ UINT_MAX);
+
+	if (check_hw_params_convention(subs)) {
+		hwc_debug("setting extra hw constraints...\n");
+		if ((err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
+					       hw_rule_rate, subs,
+					       SNDRV_PCM_HW_PARAM_FORMAT,
+					       SNDRV_PCM_HW_PARAM_CHANNELS,
+					       -1)) < 0)
+			return err;
+		if ((err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS,
+					       hw_rule_channels, subs,
+					       SNDRV_PCM_HW_PARAM_FORMAT,
+					       SNDRV_PCM_HW_PARAM_RATE,
+					       -1)) < 0)
+			return err;
+		if ((err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_FORMAT,
+					       hw_rule_format, subs,
+					       SNDRV_PCM_HW_PARAM_RATE,
+					       SNDRV_PCM_HW_PARAM_CHANNELS,
+					       -1)) < 0)
+			return err;
+	}
+	return 0;
+}
+
+static int snd_usb_pcm_open(snd_pcm_substream_t *substream, int direction,
+			    snd_pcm_hardware_t *hw)
+{
+	snd_usb_stream_t *as = snd_pcm_substream_chip(substream);
+	snd_pcm_runtime_t *runtime = substream->runtime;
+	snd_usb_substream_t *subs = &as->substream[direction];
+
+	subs->interface = -1;
+	subs->format = 0;
+	runtime->hw = *hw;
+	runtime->private_data = subs;
+	subs->pcm_substream = substream;
+	return setup_hw_info(runtime, subs);
+}
+
+static int snd_usb_pcm_close(snd_pcm_substream_t *substream, int direction)
+{
+	snd_usb_stream_t *as = snd_pcm_substream_chip(substream);
+	snd_usb_substream_t *subs = &as->substream[direction];
+
+	if (subs->interface >= 0) {
+		usb_set_interface(subs->dev, subs->interface, 0);
+		subs->interface = -1;
+	}
+	subs->pcm_substream = NULL;
+	return 0;
+}
+
+static int snd_usb_playback_open(snd_pcm_substream_t *substream)
+{
+	return snd_usb_pcm_open(substream, SNDRV_PCM_STREAM_PLAYBACK, &snd_usb_playback);
+}
+
+static int snd_usb_playback_close(snd_pcm_substream_t *substream)
+{
+	return snd_usb_pcm_close(substream, SNDRV_PCM_STREAM_PLAYBACK);
+}
+
+static int snd_usb_capture_open(snd_pcm_substream_t *substream)
+{
+	return snd_usb_pcm_open(substream, SNDRV_PCM_STREAM_CAPTURE, &snd_usb_capture);
+}
+
+static int snd_usb_capture_close(snd_pcm_substream_t *substream)
+{
+	return snd_usb_pcm_close(substream, SNDRV_PCM_STREAM_CAPTURE);
+}
+
+static snd_pcm_ops_t snd_usb_playback_ops = {
+	.open =		snd_usb_playback_open,
+	.close =	snd_usb_playback_close,
+	.ioctl =	snd_pcm_lib_ioctl,
+	.hw_params =	snd_usb_hw_params,
+	.hw_free =	snd_usb_hw_free,
+	.prepare =	snd_usb_pcm_prepare,
+	.trigger =	snd_usb_pcm_trigger,
+	.pointer =	snd_usb_pcm_pointer,
+};
+
+static snd_pcm_ops_t snd_usb_capture_ops = {
+	.open =		snd_usb_capture_open,
+	.close =	snd_usb_capture_close,
+	.ioctl =	snd_pcm_lib_ioctl,
+	.hw_params =	snd_usb_hw_params,
+	.hw_free =	snd_usb_hw_free,
+	.prepare =	snd_usb_pcm_prepare,
+	.trigger =	snd_usb_pcm_trigger,
+	.pointer =	snd_usb_pcm_pointer,
+};
+
+
+
+/*
+ * helper functions
+ */
+
+/*
+ * combine bytes and get an integer value
+ */
+unsigned int snd_usb_combine_bytes(unsigned char *bytes, int size)
+{
+	switch (size) {
+	case 1:  return *bytes;
+	case 2:  return combine_word(bytes);
+	case 3:  return combine_triple(bytes);
+	case 4:  return combine_quad(bytes);
+	default: return 0;
+	}
+}
+
+/*
+ * parse descriptor buffer and return the pointer starting the given
+ * descriptor type.
+ */
+void *snd_usb_find_desc(void *descstart, int desclen, void *after, u8 dtype)
+{
+	u8 *p, *end, *next;
+
+	p = descstart;
+	end = p + desclen;
+	for (; p < end;) {
+		if (p[0] < 2)
+			return NULL;
+		next = p + p[0];
+		if (next > end)
+			return NULL;
+		if (p[1] == dtype && (!after || (void *)p > after)) {
+			return p;
+		}
+		p = next;
+	}
+	return NULL;
+}
+
+/*
+ * find a class-specified interface descriptor with the given subtype.
+ */
+void *snd_usb_find_csint_desc(void *buffer, int buflen, void *after, u8 dsubtype)
+{
+	unsigned char *p = after;
+
+	while ((p = snd_usb_find_desc(buffer, buflen, p,
+				      USB_DT_CS_INTERFACE)) != NULL) {
+		if (p[0] >= 3 && p[2] == dsubtype)
+			return p;
+	}
+	return NULL;
+}
+
+/*
+ * Wrapper for usb_control_msg().
+ * Allocates a temp buffer to prevent dmaing from/to the stack.
+ */
+int snd_usb_ctl_msg(struct usb_device *dev, unsigned int pipe, __u8 request,
+		    __u8 requesttype, __u16 value, __u16 index, void *data,
+		    __u16 size, int timeout)
+{
+	int err;
+	void *buf = NULL;
+
+	if (size > 0) {
+		buf = kmalloc(size, GFP_KERNEL);
+		if (!buf)
+			return -ENOMEM;
+		memcpy(buf, data, size);
+	}
+	err = usb_control_msg(dev, pipe, request, requesttype,
+			      value, index, buf, size, timeout);
+	if (size > 0) {
+		memcpy(data, buf, size);
+		kfree(buf);
+	}
+	return err;
+}
+
+
+/*
+ * entry point for linux usb interface
+ */
+
+static int usb_audio_probe(struct usb_interface *intf,
+			   const struct usb_device_id *id);
+static void usb_audio_disconnect(struct usb_interface *intf);
+
+static struct usb_device_id usb_audio_ids [] = {
+#include "usbquirks.h"
+    { .match_flags = (USB_DEVICE_ID_MATCH_INT_CLASS | USB_DEVICE_ID_MATCH_INT_SUBCLASS),
+      .bInterfaceClass = USB_CLASS_AUDIO,
+      .bInterfaceSubClass = USB_SUBCLASS_AUDIO_CONTROL },
+    { }						/* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE (usb, usb_audio_ids);
+
+static struct usb_driver usb_audio_driver = {
+	.owner =	THIS_MODULE,
+	.name =		"snd-usb-audio",
+	.probe =	usb_audio_probe,
+	.disconnect =	usb_audio_disconnect,
+	.id_table =	usb_audio_ids,
+};
+
+
+/*
+ * proc interface for list the supported pcm formats
+ */
+static void proc_dump_substream_formats(snd_usb_substream_t *subs, snd_info_buffer_t *buffer)
+{
+	struct list_head *p;
+	static char *sync_types[4] = {
+		"NONE", "ASYNC", "ADAPTIVE", "SYNC"
+	};
+
+	list_for_each(p, &subs->fmt_list) {
+		struct audioformat *fp;
+		fp = list_entry(p, struct audioformat, list);
+		snd_iprintf(buffer, "  Interface %d\n", fp->iface);
+		snd_iprintf(buffer, "    Altset %d\n", fp->altsetting);
+		snd_iprintf(buffer, "    Format: %s\n", snd_pcm_format_name(fp->format));
+		snd_iprintf(buffer, "    Channels: %d\n", fp->channels);
+		snd_iprintf(buffer, "    Endpoint: %d %s (%s)\n",
+			    fp->endpoint & USB_ENDPOINT_NUMBER_MASK,
+			    fp->endpoint & USB_DIR_IN ? "IN" : "OUT",
+			    sync_types[(fp->ep_attr & EP_ATTR_MASK) >> 2]);
+		if (fp->rates & SNDRV_PCM_RATE_CONTINUOUS) {
+			snd_iprintf(buffer, "    Rates: %d - %d (continuous)\n",
+				    fp->rate_min, fp->rate_max);
+		} else {
+			unsigned int i;
+			snd_iprintf(buffer, "    Rates: ");
+			for (i = 0; i < fp->nr_rates; i++) {
+				if (i > 0)
+					snd_iprintf(buffer, ", ");
+				snd_iprintf(buffer, "%d", fp->rate_table[i]);
+			}
+			snd_iprintf(buffer, "\n");
+		}
+		// snd_iprintf(buffer, "    Max Packet Size = %d\n", fp->maxpacksize);
+		// snd_iprintf(buffer, "    EP Attribute = 0x%x\n", fp->attributes);
+	}
+}
+
+static void proc_dump_substream_status(snd_usb_substream_t *subs, snd_info_buffer_t *buffer)
+{
+	if (subs->running) {
+		unsigned int i;
+		snd_iprintf(buffer, "  Status: Running\n");
+		snd_iprintf(buffer, "    Interface = %d\n", subs->interface);
+		snd_iprintf(buffer, "    Altset = %d\n", subs->format);
+		snd_iprintf(buffer, "    URBs = %d [ ", subs->nurbs);
+		for (i = 0; i < subs->nurbs; i++)
+			snd_iprintf(buffer, "%d ", subs->dataurb[i].packets);
+		snd_iprintf(buffer, "]\n");
+		snd_iprintf(buffer, "    Packet Size = %d\n", subs->curpacksize);
+		snd_iprintf(buffer, "    Momentary freq = %u Hz\n",
+			    snd_usb_get_speed(subs->dev) == USB_SPEED_FULL
+			    ? get_full_speed_hz(subs->freqm)
+			    : get_high_speed_hz(subs->freqm));
+	} else {
+		snd_iprintf(buffer, "  Status: Stop\n");
+	}
+}
+
+static void proc_pcm_format_read(snd_info_entry_t *entry, snd_info_buffer_t *buffer)
+{
+	snd_usb_stream_t *stream = entry->private_data;
+
+	snd_iprintf(buffer, "%s : %s\n", stream->chip->card->longname, stream->pcm->name);
+
+	if (stream->substream[SNDRV_PCM_STREAM_PLAYBACK].num_formats) {
+		snd_iprintf(buffer, "\nPlayback:\n");
+		proc_dump_substream_status(&stream->substream[SNDRV_PCM_STREAM_PLAYBACK], buffer);
+		proc_dump_substream_formats(&stream->substream[SNDRV_PCM_STREAM_PLAYBACK], buffer);
+	}
+	if (stream->substream[SNDRV_PCM_STREAM_CAPTURE].num_formats) {
+		snd_iprintf(buffer, "\nCapture:\n");
+		proc_dump_substream_status(&stream->substream[SNDRV_PCM_STREAM_CAPTURE], buffer);
+		proc_dump_substream_formats(&stream->substream[SNDRV_PCM_STREAM_CAPTURE], buffer);
+	}
+}
+
+static void proc_pcm_format_add(snd_usb_stream_t *stream)
+{
+	snd_info_entry_t *entry;
+	char name[32];
+	snd_card_t *card = stream->chip->card;
+
+	sprintf(name, "stream%d", stream->pcm_index);
+	if (! snd_card_proc_new(card, name, &entry))
+		snd_info_set_text_ops(entry, stream, 1024, proc_pcm_format_read);
+}
+
+
+/*
+ * initialize the substream instance.
+ */
+
+static void init_substream(snd_usb_stream_t *as, int stream, struct audioformat *fp)
+{
+	snd_usb_substream_t *subs = &as->substream[stream];
+
+	INIT_LIST_HEAD(&subs->fmt_list);
+	spin_lock_init(&subs->lock);
+
+	subs->stream = as;
+	subs->direction = stream;
+	subs->dev = as->chip->dev;
+	if (snd_usb_get_speed(subs->dev) == USB_SPEED_FULL)
+		subs->ops = audio_urb_ops[stream];
+	else
+		subs->ops = audio_urb_ops_high_speed[stream];
+	snd_pcm_lib_preallocate_pages(as->pcm->streams[stream].substream,
+				      SNDRV_DMA_TYPE_CONTINUOUS,
+				      snd_dma_continuous_data(GFP_KERNEL),
+				      64 * 1024, 128 * 1024);
+	snd_pcm_set_ops(as->pcm, stream,
+			stream == SNDRV_PCM_STREAM_PLAYBACK ?
+			&snd_usb_playback_ops : &snd_usb_capture_ops);
+
+	list_add_tail(&fp->list, &subs->fmt_list);
+	subs->formats |= 1ULL << fp->format;
+	subs->endpoint = fp->endpoint;
+	subs->num_formats++;
+	subs->fmt_type = fp->fmt_type;
+}
+
+
+/*
+ * free a substream
+ */
+static void free_substream(snd_usb_substream_t *subs)
+{
+	struct list_head *p, *n;
+
+	if (! subs->num_formats)
+		return; /* not initialized */
+	list_for_each_safe(p, n, &subs->fmt_list) {
+		struct audioformat *fp = list_entry(p, struct audioformat, list);
+		kfree(fp->rate_table);
+		kfree(fp);
+	}
+}
+
+
+/*
+ * free a usb stream instance
+ */
+static void snd_usb_audio_stream_free(snd_usb_stream_t *stream)
+{
+	free_substream(&stream->substream[0]);
+	free_substream(&stream->substream[1]);
+	list_del(&stream->list);
+	kfree(stream);
+}
+
+static void snd_usb_audio_pcm_free(snd_pcm_t *pcm)
+{
+	snd_usb_stream_t *stream = pcm->private_data;
+	if (stream) {
+		stream->pcm = NULL;
+		snd_pcm_lib_preallocate_free_for_all(pcm);
+		snd_usb_audio_stream_free(stream);
+	}
+}
+
+
+/*
+ * add this endpoint to the chip instance.
+ * if a stream with the same endpoint already exists, append to it.
+ * if not, create a new pcm stream.
+ */
+static int add_audio_endpoint(snd_usb_audio_t *chip, int stream, struct audioformat *fp)
+{
+	struct list_head *p;
+	snd_usb_stream_t *as;
+	snd_usb_substream_t *subs;
+	snd_pcm_t *pcm;
+	int err;
+
+	list_for_each(p, &chip->pcm_list) {
+		as = list_entry(p, snd_usb_stream_t, list);
+		if (as->fmt_type != fp->fmt_type)
+			continue;
+		subs = &as->substream[stream];
+		if (! subs->endpoint)
+			continue;
+		if (subs->endpoint == fp->endpoint) {
+			list_add_tail(&fp->list, &subs->fmt_list);
+			subs->num_formats++;
+			subs->formats |= 1ULL << fp->format;
+			return 0;
+		}
+	}
+	/* look for an empty stream */
+	list_for_each(p, &chip->pcm_list) {
+		as = list_entry(p, snd_usb_stream_t, list);
+		if (as->fmt_type != fp->fmt_type)
+			continue;
+		subs = &as->substream[stream];
+		if (subs->endpoint)
+			continue;
+		err = snd_pcm_new_stream(as->pcm, stream, 1);
+		if (err < 0)
+			return err;
+		init_substream(as, stream, fp);
+		return 0;
+	}
+
+	/* create a new pcm */
+	as = kmalloc(sizeof(*as), GFP_KERNEL);
+	if (! as)
+		return -ENOMEM;
+	memset(as, 0, sizeof(*as));
+	as->pcm_index = chip->pcm_devs;
+	as->chip = chip;
+	as->fmt_type = fp->fmt_type;
+	err = snd_pcm_new(chip->card, "USB Audio", chip->pcm_devs,
+			  stream == SNDRV_PCM_STREAM_PLAYBACK ? 1 : 0,
+			  stream == SNDRV_PCM_STREAM_PLAYBACK ? 0 : 1,
+			  &pcm);
+	if (err < 0) {
+		kfree(as);
+		return err;
+	}
+	as->pcm = pcm;
+	pcm->private_data = as;
+	pcm->private_free = snd_usb_audio_pcm_free;
+	pcm->info_flags = 0;
+	if (chip->pcm_devs > 0)
+		sprintf(pcm->name, "USB Audio #%d", chip->pcm_devs);
+	else
+		strcpy(pcm->name, "USB Audio");
+
+	init_substream(as, stream, fp);
+
+	list_add(&as->list, &chip->pcm_list);
+	chip->pcm_devs++;
+
+	proc_pcm_format_add(as);
+
+	return 0;
+}
+
+
+/*
+ * check if the device uses big-endian samples
+ */
+static int is_big_endian_format(struct usb_device *dev, struct audioformat *fp)
+{
+	/* M-Audio */
+	if (le16_to_cpu(dev->descriptor.idVendor) == 0x0763) {
+		/* Quattro: captured data only */
+		if (le16_to_cpu(dev->descriptor.idProduct) == 0x2001 &&
+		    fp->endpoint & USB_DIR_IN)
+			return 1;
+		/* Audiophile USB */
+		if (le16_to_cpu(dev->descriptor.idProduct) == 0x2003)
+			return 1;
+	}
+	return 0;
+}
+
+/*
+ * parse the audio format type I descriptor
+ * and returns the corresponding pcm format
+ *
+ * @dev: usb device
+ * @fp: audioformat record
+ * @format: the format tag (wFormatTag)
+ * @fmt: the format type descriptor
+ */
+static int parse_audio_format_i_type(struct usb_device *dev, struct audioformat *fp,
+				     int format, unsigned char *fmt)
+{
+	int pcm_format;
+	int sample_width, sample_bytes;
+
+	/* FIXME: correct endianess and sign? */
+	pcm_format = -1;
+	sample_width = fmt[6];
+	sample_bytes = fmt[5];
+	switch (format) {
+	case 0: /* some devices don't define this correctly... */
+		snd_printdd(KERN_INFO "%d:%u:%d : format type 0 is detected, processed as PCM\n",
+			    dev->devnum, fp->iface, fp->altsetting);
+		/* fall-through */
+	case USB_AUDIO_FORMAT_PCM:
+		if (sample_width > sample_bytes * 8) {
+			snd_printk(KERN_INFO "%d:%u:%d : sample bitwidth %d in over sample bytes %d\n",
+				   dev->devnum, fp->iface, fp->altsetting,
+				   sample_width, sample_bytes);
+		}
+		/* check the format byte size */
+		switch (fmt[5]) {
+		case 1:
+			pcm_format = SNDRV_PCM_FORMAT_S8;
+			break;
+		case 2:
+			if (is_big_endian_format(dev, fp))
+				pcm_format = SNDRV_PCM_FORMAT_S16_BE; /* grrr, big endian!! */
+			else
+				pcm_format = SNDRV_PCM_FORMAT_S16_LE;
+			break;
+		case 3:
+			if (is_big_endian_format(dev, fp))
+				pcm_format = SNDRV_PCM_FORMAT_S24_3BE; /* grrr, big endian!! */
+			else
+				pcm_format = SNDRV_PCM_FORMAT_S24_3LE;
+			break;
+		case 4:
+			pcm_format = SNDRV_PCM_FORMAT_S32_LE;
+			break;
+		default:
+			snd_printk(KERN_INFO "%d:%u:%d : unsupported sample bitwidth %d in %d bytes\n",
+				   dev->devnum, fp->iface, fp->altsetting, sample_width, sample_bytes);
+			break;
+		}
+		break;
+	case USB_AUDIO_FORMAT_PCM8:
+		/* Dallas DS4201 workaround */
+		if (le16_to_cpu(dev->descriptor.idVendor) == 0x04fa &&
+		    le16_to_cpu(dev->descriptor.idProduct) == 0x4201)
+			pcm_format = SNDRV_PCM_FORMAT_S8;
+		else
+			pcm_format = SNDRV_PCM_FORMAT_U8;
+		break;
+	case USB_AUDIO_FORMAT_IEEE_FLOAT:
+		pcm_format = SNDRV_PCM_FORMAT_FLOAT_LE;
+		break;
+	case USB_AUDIO_FORMAT_ALAW:
+		pcm_format = SNDRV_PCM_FORMAT_A_LAW;
+		break;
+	case USB_AUDIO_FORMAT_MU_LAW:
+		pcm_format = SNDRV_PCM_FORMAT_MU_LAW;
+		break;
+	default:
+		snd_printk(KERN_INFO "%d:%u:%d : unsupported format type %d\n",
+			   dev->devnum, fp->iface, fp->altsetting, format);
+		break;
+	}
+	return pcm_format;
+}
+
+
+/*
+ * parse the format descriptor and stores the possible sample rates
+ * on the audioformat table.
+ *
+ * @dev: usb device
+ * @fp: audioformat record
+ * @fmt: the format descriptor
+ * @offset: the start offset of descriptor pointing the rate type
+ *          (7 for type I and II, 8 for type II)
+ */
+static int parse_audio_format_rates(struct usb_device *dev, struct audioformat *fp,
+				    unsigned char *fmt, int offset)
+{
+	int nr_rates = fmt[offset];
+	if (fmt[0] < offset + 1 + 3 * (nr_rates ? nr_rates : 2)) {
+		snd_printk(KERN_ERR "%d:%u:%d : invalid FORMAT_TYPE desc\n",
+				   dev->devnum, fp->iface, fp->altsetting);
+		return -1;
+	}
+
+	if (nr_rates) {
+		/*
+		 * build the rate table and bitmap flags
+		 */
+		int r, idx, c;
+		/* this table corresponds to the SNDRV_PCM_RATE_XXX bit */
+		static unsigned int conv_rates[] = {
+			5512, 8000, 11025, 16000, 22050, 32000, 44100, 48000,
+			64000, 88200, 96000, 176400, 192000
+		};
+		fp->rate_table = kmalloc(sizeof(int) * nr_rates, GFP_KERNEL);
+		if (fp->rate_table == NULL) {
+			snd_printk(KERN_ERR "cannot malloc\n");
+			return -1;
+		}
+
+		fp->nr_rates = nr_rates;
+		fp->rate_min = fp->rate_max = combine_triple(&fmt[8]);
+		for (r = 0, idx = offset + 1; r < nr_rates; r++, idx += 3) {
+			unsigned int rate = fp->rate_table[r] = combine_triple(&fmt[idx]);
+			if (rate < fp->rate_min)
+				fp->rate_min = rate;
+			else if (rate > fp->rate_max)
+				fp->rate_max = rate;
+			for (c = 0; c < (int)ARRAY_SIZE(conv_rates); c++) {
+				if (rate == conv_rates[c]) {
+					fp->rates |= (1 << c);
+					break;
+				}
+			}
+		}
+	} else {
+		/* continuous rates */
+		fp->rates = SNDRV_PCM_RATE_CONTINUOUS;
+		fp->rate_min = combine_triple(&fmt[offset + 1]);
+		fp->rate_max = combine_triple(&fmt[offset + 4]);
+	}
+	return 0;
+}
+
+/*
+ * parse the format type I and III descriptors
+ */
+static int parse_audio_format_i(struct usb_device *dev, struct audioformat *fp,
+				int format, unsigned char *fmt)
+{
+	int pcm_format;
+
+	if (fmt[3] == USB_FORMAT_TYPE_III) {
+		/* FIXME: the format type is really IECxxx
+		 *        but we give normal PCM format to get the existing
+		 *        apps working...
+		 */
+		pcm_format = SNDRV_PCM_FORMAT_S16_LE;
+	} else {
+		pcm_format = parse_audio_format_i_type(dev, fp, format, fmt);
+		if (pcm_format < 0)
+			return -1;
+	}
+	fp->format = pcm_format;
+	fp->channels = fmt[4];
+	if (fp->channels < 1) {
+		snd_printk(KERN_ERR "%d:%u:%d : invalid channels %d\n",
+			   dev->devnum, fp->iface, fp->altsetting, fp->channels);
+		return -1;
+	}
+	return parse_audio_format_rates(dev, fp, fmt, 7);
+}
+
+/*
+ * prase the format type II descriptor
+ */
+static int parse_audio_format_ii(struct usb_device *dev, struct audioformat *fp,
+				 int format, unsigned char *fmt)
+{
+	int brate, framesize;
+	switch (format) {
+	case USB_AUDIO_FORMAT_AC3:
+		/* FIXME: there is no AC3 format defined yet */
+		// fp->format = SNDRV_PCM_FORMAT_AC3;
+		fp->format = SNDRV_PCM_FORMAT_U8; /* temporarily hack to receive byte streams */
+		break;
+	case USB_AUDIO_FORMAT_MPEG:
+		fp->format = SNDRV_PCM_FORMAT_MPEG;
+		break;
+	default:
+		snd_printd(KERN_INFO "%d:%u:%d : unknown format tag 0x%x is detected.  processed as MPEG.\n",
+			   dev->devnum, fp->iface, fp->altsetting, format);
+		fp->format = SNDRV_PCM_FORMAT_MPEG;
+		break;
+	}
+	fp->channels = 1;
+	brate = combine_word(&fmt[4]); 	/* fmt[4,5] : wMaxBitRate (in kbps) */
+	framesize = combine_word(&fmt[6]); /* fmt[6,7]: wSamplesPerFrame */
+	snd_printd(KERN_INFO "found format II with max.bitrate = %d, frame size=%d\n", brate, framesize);
+	fp->frame_size = framesize;
+	return parse_audio_format_rates(dev, fp, fmt, 8); /* fmt[8..] sample rates */
+}
+
+static int parse_audio_format(struct usb_device *dev, struct audioformat *fp,
+			      int format, unsigned char *fmt, int stream)
+{
+	int err;
+
+	switch (fmt[3]) {
+	case USB_FORMAT_TYPE_I:
+	case USB_FORMAT_TYPE_III:
+		err = parse_audio_format_i(dev, fp, format, fmt);
+		break;
+	case USB_FORMAT_TYPE_II:
+		err = parse_audio_format_ii(dev, fp, format, fmt);
+		break;
+	default:
+		snd_printd(KERN_INFO "%d:%u:%d : format type %d is not supported yet\n",
+			   dev->devnum, fp->iface, fp->altsetting, fmt[3]);
+		return -1;
+	}
+	fp->fmt_type = fmt[3];
+	if (err < 0)
+		return err;
+#if 1
+	/* FIXME: temporary hack for extigy */
+	/* extigy apparently supports sample rates other than 48k
+	 * but not in ordinary way.  so we enable only 48k atm.
+	 */
+	if (le16_to_cpu(dev->descriptor.idVendor) == 0x041e && 
+	    le16_to_cpu(dev->descriptor.idProduct) == 0x3000) {
+		if (fmt[3] == USB_FORMAT_TYPE_I &&
+		    stream == SNDRV_PCM_STREAM_PLAYBACK &&
+		    fp->rates != SNDRV_PCM_RATE_48000)
+			return -1; /* use 48k only */
+	}
+#endif
+	return 0;
+}
+
+static int parse_audio_endpoints(snd_usb_audio_t *chip, int iface_no)
+{
+	struct usb_device *dev;
+	struct usb_interface *iface;
+	struct usb_host_interface *alts;
+	struct usb_interface_descriptor *altsd;
+	int i, altno, err, stream;
+	int format;
+	struct audioformat *fp;
+	unsigned char *fmt, *csep;
+
+	dev = chip->dev;
+
+	/* parse the interface's altsettings */
+	iface = usb_ifnum_to_if(dev, iface_no);
+	for (i = 0; i < iface->num_altsetting; i++) {
+		alts = &iface->altsetting[i];
+		altsd = get_iface_desc(alts);
+		/* skip invalid one */
+		if ((altsd->bInterfaceClass != USB_CLASS_AUDIO &&
+		     altsd->bInterfaceClass != USB_CLASS_VENDOR_SPEC) ||
+		    (altsd->bInterfaceSubClass != USB_SUBCLASS_AUDIO_STREAMING &&
+		     altsd->bInterfaceSubClass != USB_SUBCLASS_VENDOR_SPEC) ||
+		    altsd->bNumEndpoints < 1 ||
+		    le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize) == 0)
+			continue;
+		/* must be isochronous */
+		if ((get_endpoint(alts, 0)->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) !=
+		    USB_ENDPOINT_XFER_ISOC)
+			continue;
+		/* check direction */
+		stream = (get_endpoint(alts, 0)->bEndpointAddress & USB_DIR_IN) ?
+			SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK;
+		altno = altsd->bAlternateSetting;
+
+		/* get audio formats */
+		fmt = snd_usb_find_csint_desc(alts->extra, alts->extralen, NULL, AS_GENERAL);
+		if (!fmt) {
+			snd_printk(KERN_ERR "%d:%u:%d : AS_GENERAL descriptor not found\n",
+				   dev->devnum, iface_no, altno);
+			continue;
+		}
+
+		if (fmt[0] < 7) {
+			snd_printk(KERN_ERR "%d:%u:%d : invalid AS_GENERAL desc\n",
+				   dev->devnum, iface_no, altno);
+			continue;
+		}
+
+		format = (fmt[6] << 8) | fmt[5]; /* remember the format value */
+
+		/* get format type */
+		fmt = snd_usb_find_csint_desc(alts->extra, alts->extralen, NULL, FORMAT_TYPE);
+		if (!fmt) {
+			snd_printk(KERN_ERR "%d:%u:%d : no FORMAT_TYPE desc\n",
+				   dev->devnum, iface_no, altno);
+			continue;
+		}
+		if (fmt[0] < 8) {
+			snd_printk(KERN_ERR "%d:%u:%d : invalid FORMAT_TYPE desc\n",
+				   dev->devnum, iface_no, altno);
+			continue;
+		}
+
+		csep = snd_usb_find_desc(alts->endpoint[0].extra, alts->endpoint[0].extralen, NULL, USB_DT_CS_ENDPOINT);
+		/* Creamware Noah has this descriptor after the 2nd endpoint */
+		if (!csep && altsd->bNumEndpoints >= 2)
+			csep = snd_usb_find_desc(alts->endpoint[1].extra, alts->endpoint[1].extralen, NULL, USB_DT_CS_ENDPOINT);
+		if (!csep || csep[0] < 7 || csep[2] != EP_GENERAL) {
+			snd_printk(KERN_ERR "%d:%u:%d : no or invalid class specific endpoint descriptor\n",
+				   dev->devnum, iface_no, altno);
+			continue;
+		}
+
+		fp = kmalloc(sizeof(*fp), GFP_KERNEL);
+		if (! fp) {
+			snd_printk(KERN_ERR "cannot malloc\n");
+			return -ENOMEM;
+		}
+
+		memset(fp, 0, sizeof(*fp));
+		fp->iface = iface_no;
+		fp->altsetting = altno;
+		fp->altset_idx = i;
+		fp->endpoint = get_endpoint(alts, 0)->bEndpointAddress;
+		fp->ep_attr = get_endpoint(alts, 0)->bmAttributes;
+		/* FIXME: decode wMaxPacketSize of high bandwith endpoints */
+		fp->maxpacksize = le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize);
+		fp->attributes = csep[3];
+
+		/* some quirks for attributes here */
+
+		/* workaround for AudioTrak Optoplay */
+		if (le16_to_cpu(dev->descriptor.idVendor) == 0x0a92 &&
+		    le16_to_cpu(dev->descriptor.idProduct) == 0x0053) {
+			/* Optoplay sets the sample rate attribute although
+			 * it seems not supporting it in fact.
+			 */
+			fp->attributes &= ~EP_CS_ATTR_SAMPLE_RATE;
+		}
+
+		/* workaround for M-Audio Audiophile USB */
+		if (le16_to_cpu(dev->descriptor.idVendor) == 0x0763 &&
+		    le16_to_cpu(dev->descriptor.idProduct) == 0x2003) {
+			/* doesn't set the sample rate attribute, but supports it */
+			fp->attributes |= EP_CS_ATTR_SAMPLE_RATE;
+		}
+
+		/*
+		 * plantronics headset and Griffin iMic have set adaptive-in
+		 * although it's really not...
+		 */
+		if ((le16_to_cpu(dev->descriptor.idVendor) == 0x047f &&
+		     le16_to_cpu(dev->descriptor.idProduct) == 0x0ca1) ||
+		    /* Griffin iMic (note that there is an older model 77d:223) */
+		    (le16_to_cpu(dev->descriptor.idVendor) == 0x077d &&
+		     le16_to_cpu(dev->descriptor.idProduct) == 0x07af)) {
+			fp->ep_attr &= ~EP_ATTR_MASK;
+			if (stream == SNDRV_PCM_STREAM_PLAYBACK)
+				fp->ep_attr |= EP_ATTR_ADAPTIVE;
+			else
+				fp->ep_attr |= EP_ATTR_SYNC;
+		}
+
+		/* ok, let's parse further... */
+		if (parse_audio_format(dev, fp, format, fmt, stream) < 0) {
+			kfree(fp->rate_table);
+			kfree(fp);
+			continue;
+		}
+
+		snd_printdd(KERN_INFO "%d:%u:%d: add audio endpoint 0x%x\n", dev->devnum, iface_no, i, fp->endpoint);
+		err = add_audio_endpoint(chip, stream, fp);
+		if (err < 0) {
+			kfree(fp->rate_table);
+			kfree(fp);
+			return err;
+		}
+		/* try to set the interface... */
+		usb_set_interface(chip->dev, iface_no, altno);
+		init_usb_pitch(chip->dev, iface_no, alts, fp);
+		init_usb_sample_rate(chip->dev, iface_no, alts, fp, fp->rate_max);
+	}
+	return 0;
+}
+
+
+/*
+ * disconnect streams
+ * called from snd_usb_audio_disconnect()
+ */
+static void snd_usb_stream_disconnect(struct list_head *head, struct usb_driver *driver)
+{
+	int idx;
+	snd_usb_stream_t *as;
+	snd_usb_substream_t *subs;
+
+	as = list_entry(head, snd_usb_stream_t, list);
+	for (idx = 0; idx < 2; idx++) {
+		subs = &as->substream[idx];
+		if (!subs->num_formats)
+			return;
+		release_substream_urbs(subs, 1);
+		subs->interface = -1;
+	}
+}
+
+/*
+ * parse audio control descriptor and create pcm/midi streams
+ */
+static int snd_usb_create_streams(snd_usb_audio_t *chip, int ctrlif)
+{
+	struct usb_device *dev = chip->dev;
+	struct usb_host_interface *host_iface;
+	struct usb_interface *iface;
+	unsigned char *p1;
+	int i, j;
+
+	/* find audiocontrol interface */
+	host_iface = &usb_ifnum_to_if(dev, ctrlif)->altsetting[0];
+	if (!(p1 = snd_usb_find_csint_desc(host_iface->extra, host_iface->extralen, NULL, HEADER))) {
+		snd_printk(KERN_ERR "cannot find HEADER\n");
+		return -EINVAL;
+	}
+	if (! p1[7] || p1[0] < 8 + p1[7]) {
+		snd_printk(KERN_ERR "invalid HEADER\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * parse all USB audio streaming interfaces
+	 */
+	for (i = 0; i < p1[7]; i++) {
+		struct usb_host_interface *alts;
+		struct usb_interface_descriptor *altsd;
+		j = p1[8 + i];
+		iface = usb_ifnum_to_if(dev, j);
+		if (!iface) {
+			snd_printk(KERN_ERR "%d:%u:%d : does not exist\n",
+				   dev->devnum, ctrlif, j);
+			continue;
+		}
+		if (usb_interface_claimed(iface)) {
+			snd_printdd(KERN_INFO "%d:%d:%d: skipping, already claimed\n", dev->devnum, ctrlif, j);
+			continue;
+		}
+		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_MIDI_STREAMING) {
+			if (snd_usb_create_midi_interface(chip, iface, NULL) < 0) {
+				snd_printk(KERN_ERR "%d:%u:%d: cannot create sequencer device\n", dev->devnum, ctrlif, j);
+				continue;
+			}
+			usb_driver_claim_interface(&usb_audio_driver, iface, (void *)-1L);
+			continue;
+		}
+		if ((altsd->bInterfaceClass != USB_CLASS_AUDIO &&
+		     altsd->bInterfaceClass != USB_CLASS_VENDOR_SPEC) ||
+		    altsd->bInterfaceSubClass != USB_SUBCLASS_AUDIO_STREAMING) {
+			snd_printdd(KERN_ERR "%d:%u:%d: skipping non-supported interface %d\n", dev->devnum, ctrlif, j, altsd->bInterfaceClass);
+			/* skip non-supported classes */
+			continue;
+		}
+		if (! parse_audio_endpoints(chip, j)) {
+			usb_set_interface(dev, j, 0); /* reset the current interface */
+			usb_driver_claim_interface(&usb_audio_driver, iface, (void *)-1L);
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * create a stream for an endpoint/altsetting without proper descriptors
+ */
+static int create_fixed_stream_quirk(snd_usb_audio_t *chip,
+				     struct usb_interface *iface,
+				     const snd_usb_audio_quirk_t *quirk)
+{
+	struct audioformat *fp;
+	struct usb_host_interface *alts;
+	int stream, err;
+	int *rate_table = NULL;
+
+	fp = kmalloc(sizeof(*fp), GFP_KERNEL);
+	if (! fp) {
+		snd_printk(KERN_ERR "cannot malloc\n");
+		return -ENOMEM;
+	}
+	memcpy(fp, quirk->data, sizeof(*fp));
+	if (fp->nr_rates > 0) {
+		rate_table = kmalloc(sizeof(int) * fp->nr_rates, GFP_KERNEL);
+		if (!rate_table) {
+			kfree(fp);
+			return -ENOMEM;
+		}
+		memcpy(rate_table, fp->rate_table, sizeof(int) * fp->nr_rates);
+		fp->rate_table = rate_table;
+	}
+
+	stream = (fp->endpoint & USB_DIR_IN)
+		? SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK;
+	err = add_audio_endpoint(chip, stream, fp);
+	if (err < 0) {
+		kfree(fp);
+		kfree(rate_table);
+		return err;
+	}
+	if (fp->iface != get_iface_desc(&iface->altsetting[0])->bInterfaceNumber ||
+	    fp->altset_idx >= iface->num_altsetting) {
+		kfree(fp);
+		kfree(rate_table);
+		return -EINVAL;
+	}
+	alts = &iface->altsetting[fp->altset_idx];
+	usb_set_interface(chip->dev, fp->iface, 0);
+	init_usb_pitch(chip->dev, fp->iface, alts, fp);
+	init_usb_sample_rate(chip->dev, fp->iface, alts, fp, fp->rate_max);
+	return 0;
+}
+
+/*
+ * create a stream for an interface with proper descriptors
+ */
+static int create_standard_interface_quirk(snd_usb_audio_t *chip,
+					   struct usb_interface *iface,
+					   const snd_usb_audio_quirk_t *quirk)
+{
+	struct usb_host_interface *alts;
+	struct usb_interface_descriptor *altsd;
+	int err;
+
+	alts = &iface->altsetting[0];
+	altsd = get_iface_desc(alts);
+	switch (quirk->type) {
+	case QUIRK_AUDIO_STANDARD_INTERFACE:
+		err = parse_audio_endpoints(chip, altsd->bInterfaceNumber);
+		if (!err)
+			usb_set_interface(chip->dev, altsd->bInterfaceNumber, 0); /* reset the current interface */
+		break;
+	case QUIRK_MIDI_STANDARD_INTERFACE:
+		err = snd_usb_create_midi_interface(chip, iface, NULL);
+		break;
+	default:
+		snd_printd(KERN_ERR "invalid quirk type %d\n", quirk->type);
+		return -ENXIO;
+	}
+	if (err < 0) {
+		snd_printk(KERN_ERR "cannot setup if %d: error %d\n",
+			   altsd->bInterfaceNumber, err);
+		return err;
+	}
+	return 0;
+}
+
+/*
+ * Create a stream for an Edirol UA-700/UA-25 interface.  The only way
+ * to detect the sample rate is by looking at wMaxPacketSize.
+ */
+static int create_ua700_ua25_quirk(snd_usb_audio_t *chip,
+				   struct usb_interface *iface)
+{
+	static const struct audioformat ua_format = {
+		.format = SNDRV_PCM_FORMAT_S24_3LE,
+		.channels = 2,
+		.fmt_type = USB_FORMAT_TYPE_I,
+		.altsetting = 1,
+		.altset_idx = 1,
+		.rates = SNDRV_PCM_RATE_CONTINUOUS,
+	};
+	struct usb_host_interface *alts;
+	struct usb_interface_descriptor *altsd;
+	struct audioformat *fp;
+	int stream, err;
+
+	/* both PCM and MIDI interfaces have 2 altsettings */
+	if (iface->num_altsetting != 2)
+		return -ENXIO;
+	alts = &iface->altsetting[1];
+	altsd = get_iface_desc(alts);
+
+	if (altsd->bNumEndpoints == 2) {
+		static const snd_usb_midi_endpoint_info_t ua700_ep = {
+			.out_cables = 0x0003,
+			.in_cables  = 0x0003
+		};
+		static const snd_usb_audio_quirk_t ua700_quirk = {
+			.type = QUIRK_MIDI_FIXED_ENDPOINT,
+			.data = &ua700_ep
+		};
+		static const snd_usb_midi_endpoint_info_t ua25_ep = {
+			.out_cables = 0x0001,
+			.in_cables  = 0x0001
+		};
+		static const snd_usb_audio_quirk_t ua25_quirk = {
+			.type = QUIRK_MIDI_FIXED_ENDPOINT,
+			.data = &ua25_ep
+		};
+		if (le16_to_cpu(chip->dev->descriptor.idProduct) == 0x002b)
+			return snd_usb_create_midi_interface(chip, iface,
+							     &ua700_quirk);
+		else
+			return snd_usb_create_midi_interface(chip, iface,
+							     &ua25_quirk);
+	}
+
+	if (altsd->bNumEndpoints != 1)
+		return -ENXIO;
+
+	fp = kmalloc(sizeof(*fp), GFP_KERNEL);
+	if (!fp)
+		return -ENOMEM;
+	memcpy(fp, &ua_format, sizeof(*fp));
+
+	fp->iface = altsd->bInterfaceNumber;
+	fp->endpoint = get_endpoint(alts, 0)->bEndpointAddress;
+	fp->ep_attr = get_endpoint(alts, 0)->bmAttributes;
+	fp->maxpacksize = le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize);
+
+	switch (fp->maxpacksize) {
+	case 0x120:
+		fp->rate_max = fp->rate_min = 44100;
+		break;
+	case 0x138:
+	case 0x140:
+		fp->rate_max = fp->rate_min = 48000;
+		break;
+	case 0x258:
+	case 0x260:
+		fp->rate_max = fp->rate_min = 96000;
+		break;
+	default:
+		snd_printk(KERN_ERR "unknown sample rate\n");
+		kfree(fp);
+		return -ENXIO;
+	}
+
+	stream = (fp->endpoint & USB_DIR_IN)
+		? SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK;
+	err = add_audio_endpoint(chip, stream, fp);
+	if (err < 0) {
+		kfree(fp);
+		return err;
+	}
+	usb_set_interface(chip->dev, fp->iface, 0);
+	return 0;
+}
+
+/*
+ * Create a stream for an Edirol UA-1000 interface.
+ */
+static int create_ua1000_quirk(snd_usb_audio_t *chip, struct usb_interface *iface)
+{
+	static const struct audioformat ua1000_format = {
+		.format = SNDRV_PCM_FORMAT_S32_LE,
+		.fmt_type = USB_FORMAT_TYPE_I,
+		.altsetting = 1,
+		.altset_idx = 1,
+		.attributes = 0,
+		.rates = SNDRV_PCM_RATE_CONTINUOUS,
+	};
+	struct usb_host_interface *alts;
+	struct usb_interface_descriptor *altsd;
+	struct audioformat *fp;
+	int stream, err;
+
+	if (iface->num_altsetting != 2)
+		return -ENXIO;
+	alts = &iface->altsetting[1];
+	altsd = get_iface_desc(alts);
+	if (alts->extralen != 11 || alts->extra[1] != CS_AUDIO_INTERFACE ||
+	    altsd->bNumEndpoints != 1)
+		return -ENXIO;
+
+	fp = kmalloc(sizeof(*fp), GFP_KERNEL);
+	if (!fp)
+		return -ENOMEM;
+	memcpy(fp, &ua1000_format, sizeof(*fp));
+
+	fp->channels = alts->extra[4];
+	fp->iface = altsd->bInterfaceNumber;
+	fp->endpoint = get_endpoint(alts, 0)->bEndpointAddress;
+	fp->ep_attr = get_endpoint(alts, 0)->bmAttributes;
+	fp->maxpacksize = le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize);
+	fp->rate_max = fp->rate_min = combine_triple(&alts->extra[8]);
+
+	stream = (fp->endpoint & USB_DIR_IN)
+		? SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK;
+	err = add_audio_endpoint(chip, stream, fp);
+	if (err < 0) {
+		kfree(fp);
+		return err;
+	}
+	/* FIXME: playback must be synchronized to capture */
+	usb_set_interface(chip->dev, fp->iface, 0);
+	return 0;
+}
+
+static int snd_usb_create_quirk(snd_usb_audio_t *chip,
+				struct usb_interface *iface,
+				const snd_usb_audio_quirk_t *quirk);
+
+/*
+ * handle the quirks for the contained interfaces
+ */
+static int create_composite_quirk(snd_usb_audio_t *chip,
+				  struct usb_interface *iface,
+				  const snd_usb_audio_quirk_t *quirk)
+{
+	int probed_ifnum = get_iface_desc(iface->altsetting)->bInterfaceNumber;
+	int err;
+
+	for (quirk = quirk->data; quirk->ifnum >= 0; ++quirk) {
+		iface = usb_ifnum_to_if(chip->dev, quirk->ifnum);
+		if (!iface)
+			continue;
+		if (quirk->ifnum != probed_ifnum &&
+		    usb_interface_claimed(iface))
+			continue;
+		err = snd_usb_create_quirk(chip, iface, quirk);
+		if (err < 0)
+			return err;
+		if (quirk->ifnum != probed_ifnum)
+			usb_driver_claim_interface(&usb_audio_driver, iface, (void *)-1L);
+	}
+	return 0;
+}
+
+
+/*
+ * boot quirks
+ */
+
+#define EXTIGY_FIRMWARE_SIZE_OLD 794
+#define EXTIGY_FIRMWARE_SIZE_NEW 483
+
+static int snd_usb_extigy_boot_quirk(struct usb_device *dev, struct usb_interface *intf)
+{
+	struct usb_host_config *config = dev->actconfig;
+	int err;
+
+	if (le16_to_cpu(get_cfg_desc(config)->wTotalLength) == EXTIGY_FIRMWARE_SIZE_OLD ||
+	    le16_to_cpu(get_cfg_desc(config)->wTotalLength) == EXTIGY_FIRMWARE_SIZE_NEW) {
+		snd_printdd("sending Extigy boot sequence...\n");
+		/* Send message to force it to reconnect with full interface. */
+		err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev,0),
+				      0x10, 0x43, 0x0001, 0x000a, NULL, 0, 1000);
+		if (err < 0) snd_printdd("error sending boot message: %d\n", err);
+		err = usb_get_descriptor(dev, USB_DT_DEVICE, 0,
+				&dev->descriptor, sizeof(dev->descriptor));
+		config = dev->actconfig;
+		if (err < 0) snd_printdd("error usb_get_descriptor: %d\n", err);
+		err = usb_reset_configuration(dev);
+		if (err < 0) snd_printdd("error usb_reset_configuration: %d\n", err);
+		snd_printdd("extigy_boot: new boot length = %d\n",
+			    le16_to_cpu(get_cfg_desc(config)->wTotalLength));
+		return -ENODEV; /* quit this anyway */
+	}
+	return 0;
+}
+
+
+/*
+ * audio-interface quirks
+ *
+ * returns zero if no standard audio/MIDI parsing is needed.
+ * returns a postive value if standard audio/midi interfaces are parsed
+ * after this.
+ * returns a negative value at error.
+ */
+static int snd_usb_create_quirk(snd_usb_audio_t *chip,
+				struct usb_interface *iface,
+				const snd_usb_audio_quirk_t *quirk)
+{
+	switch (quirk->type) {
+	case QUIRK_MIDI_FIXED_ENDPOINT:
+	case QUIRK_MIDI_YAMAHA:
+	case QUIRK_MIDI_MIDIMAN:
+	case QUIRK_MIDI_NOVATION:
+	case QUIRK_MIDI_MOTU:
+	case QUIRK_MIDI_EMAGIC:
+		return snd_usb_create_midi_interface(chip, iface, quirk);
+	case QUIRK_COMPOSITE:
+		return create_composite_quirk(chip, iface, quirk);
+	case QUIRK_AUDIO_FIXED_ENDPOINT:
+		return create_fixed_stream_quirk(chip, iface, quirk);
+	case QUIRK_AUDIO_STANDARD_INTERFACE:
+	case QUIRK_MIDI_STANDARD_INTERFACE:
+		return create_standard_interface_quirk(chip, iface, quirk);
+	case QUIRK_AUDIO_EDIROL_UA700_UA25:
+		return create_ua700_ua25_quirk(chip, iface);
+	case QUIRK_AUDIO_EDIROL_UA1000:
+		return create_ua1000_quirk(chip, iface);
+	case QUIRK_IGNORE_INTERFACE:
+		return 0;
+	default:
+		snd_printd(KERN_ERR "invalid quirk type %d\n", quirk->type);
+		return -ENXIO;
+	}
+}
+
+
+/*
+ * common proc files to show the usb device info
+ */
+static void proc_audio_usbbus_read(snd_info_entry_t *entry, snd_info_buffer_t *buffer)
+{
+	snd_usb_audio_t *chip = entry->private_data;
+	if (! chip->shutdown)
+		snd_iprintf(buffer, "%03d/%03d\n", chip->dev->bus->busnum, chip->dev->devnum);
+}
+
+static void proc_audio_usbid_read(snd_info_entry_t *entry, snd_info_buffer_t *buffer)
+{
+	snd_usb_audio_t *chip = entry->private_data;
+	if (! chip->shutdown)
+		snd_iprintf(buffer, "%04x:%04x\n", 
+			    le16_to_cpu(chip->dev->descriptor.idVendor),
+			    le16_to_cpu(chip->dev->descriptor.idProduct));
+}
+
+static void snd_usb_audio_create_proc(snd_usb_audio_t *chip)
+{
+	snd_info_entry_t *entry;
+	if (! snd_card_proc_new(chip->card, "usbbus", &entry))
+		snd_info_set_text_ops(entry, chip, 1024, proc_audio_usbbus_read);
+	if (! snd_card_proc_new(chip->card, "usbid", &entry))
+		snd_info_set_text_ops(entry, chip, 1024, proc_audio_usbid_read);
+}
+
+/*
+ * free the chip instance
+ *
+ * here we have to do not much, since pcm and controls are already freed
+ *
+ */
+
+static int snd_usb_audio_free(snd_usb_audio_t *chip)
+{
+	kfree(chip);
+	return 0;
+}
+
+static int snd_usb_audio_dev_free(snd_device_t *device)
+{
+	snd_usb_audio_t *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 snd_usb_audio_quirk_t *quirk,
+				snd_usb_audio_t **rchip)
+{
+	snd_card_t *card;
+	snd_usb_audio_t *chip;
+	int err, len;
+	char component[14];
+	static snd_device_ops_t ops = {
+		.dev_free =	snd_usb_audio_dev_free,
+	};
+
+	*rchip = NULL;
+
+	if (snd_usb_get_speed(dev) != USB_SPEED_FULL &&
+	    snd_usb_get_speed(dev) != USB_SPEED_HIGH) {
+		snd_printk(KERN_ERR "unknown device speed %d\n", snd_usb_get_speed(dev));
+		return -ENXIO;
+	}
+
+	card = snd_card_new(index[idx], id[idx], THIS_MODULE, 0);
+	if (card == NULL) {
+		snd_printk(KERN_ERR "cannot create card instance %d\n", idx);
+		return -ENOMEM;
+	}
+
+	chip = kcalloc(1, sizeof(*chip), GFP_KERNEL);
+	if (! chip) {
+		snd_card_free(card);
+		return -ENOMEM;
+	}
+
+	chip->index = idx;
+	chip->dev = dev;
+	chip->card = card;
+	INIT_LIST_HEAD(&chip->pcm_list);
+	INIT_LIST_HEAD(&chip->midi_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",
+		le16_to_cpu(dev->descriptor.idVendor),
+		le16_to_cpu(dev->descriptor.idProduct));
+	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",
+				le16_to_cpu(dev->descriptor.idVendor),
+				le16_to_cpu(dev->descriptor.idProduct));
+		}
+	}
+
+	/* 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);
+
+	strlcat(card->longname,
+		snd_usb_get_speed(dev) == USB_SPEED_FULL ? ", full speed" : ", high speed",
+		sizeof(card->longname));
+
+	snd_usb_audio_create_proc(chip);
+
+	snd_card_set_dev(card, &dev->dev);
+
+	*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)
+{
+	struct usb_host_config *config = dev->actconfig;
+	const snd_usb_audio_quirk_t *quirk = (const snd_usb_audio_quirk_t *)usb_id->driver_info;
+	int i, err;
+	snd_usb_audio_t *chip;
+	struct usb_host_interface *alts;
+	int ifnum;
+
+	alts = &intf->altsetting[0];
+	ifnum = get_iface_desc(alts)->bInterfaceNumber;
+
+	if (quirk && quirk->ifnum >= 0 && ifnum != quirk->ifnum)
+		goto __err_val;
+
+	/* SB Extigy needs special boot-up sequence */
+	/* if more models come, this will go to the quirk list. */
+	if (le16_to_cpu(dev->descriptor.idVendor) == 0x041e && 
+	    le16_to_cpu(dev->descriptor.idProduct) == 0x3000) {
+		if (snd_usb_extigy_boot_quirk(dev, intf) < 0)
+			goto __err_val;
+		config = dev->actconfig;
+	}
+
+	/*
+	 * found a config.  now register to ALSA
+	 */
+
+	/* check whether it's already registered */
+	chip = NULL;
+	down(&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
+		 */
+		/* first, set the current configuration for this device */
+		if (usb_reset_configuration(dev) < 0) {
+			snd_printk(KERN_ERR "cannot reset configuration (value 0x%x)\n", get_cfg_desc(config)->bConfigurationValue);
+			goto __error;
+		}
+		for (i = 0; i < SNDRV_CARDS; i++)
+			if (enable[i] && ! usb_chip[i] &&
+			    (vid[i] == -1 || vid[i] == le16_to_cpu(dev->descriptor.idVendor)) &&
+			    (pid[i] == -1 || pid[i] == le16_to_cpu(dev->descriptor.idProduct))) {
+				if (snd_usb_audio_create(dev, i, quirk, &chip) < 0) {
+					goto __error;
+				}
+				break;
+			}
+		if (! chip) {
+			snd_printk(KERN_ERR "no available usb audio device\n");
+			goto __error;
+		}
+	}
+
+	err = 1; /* continue */
+	if (quirk && quirk->ifnum != QUIRK_NO_INTERFACE) {
+		/* need some special handlings */
+		if ((err = snd_usb_create_quirk(chip, intf, quirk)) < 0)
+			goto __error;
+	}
+
+	if (err > 0) {
+		/* create normal USB audio interfaces */
+		if (snd_usb_create_streams(chip, ifnum) < 0 ||
+		    snd_usb_create_mixer(chip, ifnum) < 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++;
+	up(&register_mutex);
+	return chip;
+
+ __error:
+	if (chip && !chip->num_interfaces)
+		snd_card_free(chip->card);
+	up(&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)
+{
+	snd_usb_audio_t *chip;
+	snd_card_t *card;
+	struct list_head *p;
+
+	if (ptr == (void *)-1L)
+		return;
+
+	chip = ptr;
+	card = chip->card;
+	down(&register_mutex);
+	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, &usb_audio_driver);
+		}
+		/* release the midi resources */
+		list_for_each(p, &chip->midi_list) {
+			snd_usbmidi_disconnect(p, &usb_audio_driver);
+		}
+		usb_chip[chip->index] = NULL;
+		up(&register_mutex);
+		snd_card_free_in_thread(card);
+	} else {
+		up(&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) {
+		dev_set_drvdata(&intf->dev, chip);
+		return 0;
+	} else
+		return -EIO;
+}
+
+static void usb_audio_disconnect(struct usb_interface *intf)
+{
+	snd_usb_audio_disconnect(interface_to_usbdev(intf),
+				 dev_get_drvdata(&intf->dev));
+}
+
+
+static int __init snd_usb_audio_init(void)
+{
+	if (nrpacks < MIN_PACKS_URB || nrpacks > MAX_PACKS) {
+		printk(KERN_WARNING "invalid nrpacks value.\n");
+		return -EINVAL;
+	}
+	usb_register(&usb_audio_driver);
+	return 0;
+}
+
+
+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);