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usbaudio.c

/*
 *   (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 <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/vmalloc.h>
#include <linux/moduleparam.h>
#include <linux/mutex.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 = 8;       /* max. number of packets per urb */
static int async_unlink = 1;
static int device_setup[SNDRV_CARDS]; /* device parameter for this card*/

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


/*
 * debug the h/w constraints
 */
/* #define HW_CONST_DEBUG */


/*
 *
 */

#define MAX_PACKS 20
#define MAX_PACKS_HS    (MAX_PACKS * 8)   /* in high speed mode */
#define MAX_URBS  8
#define SYNC_URBS 4     /* always four urbs for sync */
#define MIN_PACKS_URB   1     /* minimum 1 packet per urb */

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_usb_substream;

struct snd_urb_ctx {
      struct urb *urb;
      unsigned int buffer_size;     /* size of data buffer, if data URB */
      struct snd_usb_substream *subs;
      int index;  /* index for urb array */
      int packets;      /* number of packets per urb */
};

struct snd_urb_ops {
      int (*prepare)(struct snd_usb_substream *subs, struct snd_pcm_runtime *runtime, struct urb *u);
      int (*retire)(struct snd_usb_substream *subs, struct snd_pcm_runtime *runtime, struct urb *u);
      int (*prepare_sync)(struct snd_usb_substream *subs, struct snd_pcm_runtime *runtime, struct urb *u);
      int (*retire_sync)(struct snd_usb_substream *subs, struct snd_pcm_runtime *runtime, struct urb *u);
};

struct snd_usb_substream {
      struct snd_usb_stream *stream;
      struct usb_device *dev;
      struct snd_pcm_substream *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 datainterval;    /* log_2 of data packet interval */
      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 packs_per_ms;    /* packets per millisecond (for playback) */

      unsigned int running: 1;      /* running status */

      unsigned int hwptr_done;                  /* processed frame position in the buffer */
      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 */
      struct snd_urb_ctx dataurb[MAX_URBS];     /* data urb table */
      struct snd_urb_ctx syncurb[SYNC_URBS];    /* sync urb table */
      char *syncbuf;                      /* sync buffer for all sync URBs */
      dma_addr_t sync_dma;                /* DMA address of syncbuf */

      u64 formats;                  /* format bitmasks (all or'ed) */
      unsigned int num_formats;           /* number of supported audio formats (list) */
      struct list_head fmt_list;    /* format list */
      struct snd_pcm_hw_constraint_list rate_list;    /* limited rates */
      spinlock_t lock;

      struct snd_urb_ops ops;       /* callbacks (must be filled at init) */
};


struct snd_usb_stream {
      struct snd_usb_audio *chip;
      struct snd_pcm *pcm;
      int pcm_index;
      unsigned int fmt_type;        /* USB audio format type (1-3) */
      struct snd_usb_substream 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 DEFINE_MUTEX(register_mutex);
static struct snd_usb_audio *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
 */
static inline 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
 */
static inline 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 */
static inline 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 */
static inline 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(struct snd_usb_substream *subs,
                            struct snd_pcm_runtime *runtime,
                            struct urb *urb)
{
      unsigned char *cp = urb->transfer_buffer;
      struct snd_urb_ctx *ctx = urb->context;

      urb->dev = ctx->subs->dev; /* we need to set this at each time */
      urb->iso_frame_desc[0].length = 3;
      urb->iso_frame_desc[0].offset = 0;
      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(struct snd_usb_substream *subs,
                               struct snd_pcm_runtime *runtime,
                               struct urb *urb)
{
      unsigned char *cp = urb->transfer_buffer;
      struct snd_urb_ctx *ctx = urb->context;

      urb->dev = ctx->subs->dev; /* we need to set this at each time */
      urb->iso_frame_desc[0].length = 4;
      urb->iso_frame_desc[0].offset = 0;
      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(struct snd_usb_substream *subs,
                           struct snd_pcm_runtime *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(struct snd_usb_substream *subs,
                         struct snd_pcm_runtime *runtime,
                         struct urb *urb)
{
      int i, offs;
      struct snd_urb_ctx *ctx = urb->context;

      offs = 0;
      urb->dev = ctx->subs->dev; /* we need to set this at each time */
      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->transfer_buffer_length = offs;
      urb->number_of_packets = ctx->packets;
      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(struct snd_usb_substream *subs,
                        struct snd_pcm_runtime *runtime,
                        struct urb *urb)
{
      unsigned long flags;
      unsigned char *cp;
      int i;
      unsigned int stride, len, oldptr;
      int period_elapsed = 0;

      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;
            if (subs->transfer_done >= runtime->period_size) {
                  subs->transfer_done -= runtime->period_size;
                  period_elapsed = 1;
            }
            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);
            }
      }
      if (period_elapsed)
            snd_pcm_period_elapsed(subs->pcm_substream);
      return 0;
}

/*
 * Process after capture complete when paused.  Nothing to do.
 */
static int retire_paused_capture_urb(struct snd_usb_substream *subs,
                             struct snd_pcm_runtime *runtime,
                             struct urb *urb)
{
      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(struct snd_usb_substream *subs,
                             struct snd_pcm_runtime *runtime,
                             struct urb *urb)
{
      struct snd_urb_ctx *ctx = urb->context;

      urb->dev = ctx->subs->dev; /* we need to set this at each time */
      urb->iso_frame_desc[0].length = 3;
      urb->iso_frame_desc[0].offset = 0;
      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(struct snd_usb_substream *subs,
                              struct snd_pcm_runtime *runtime,
                              struct urb *urb)
{
      struct snd_urb_ctx *ctx = urb->context;

      urb->dev = ctx->subs->dev; /* we need to set this at each time */
      urb->iso_frame_desc[0].length = 4;
      urb->iso_frame_desc[0].offset = 0;
      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(struct snd_usb_substream *subs,
                            struct snd_pcm_runtime *runtime,
                            struct urb *urb)
{
      unsigned int f;
      unsigned long flags;

      if (urb->iso_frame_desc[0].status == 0 &&
          urb->iso_frame_desc[0].actual_length == 3) {
            f = combine_triple((u8*)urb->transfer_buffer) << 2;
            if (f >= subs->freqn - subs->freqn / 8 && f <= subs->freqmax) {
                  spin_lock_irqsave(&subs->lock, flags);
                  subs->freqm = f;
                  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(struct snd_usb_substream *subs,
                               struct snd_pcm_runtime *runtime,
                               struct urb *urb)
{
      unsigned int f;
      unsigned long flags;

      if (urb->iso_frame_desc[0].status == 0 &&
          urb->iso_frame_desc[0].actual_length == 4) {
            f = combine_quad((u8*)urb->transfer_buffer) & 0x0fffffff;
            if (f >= subs->freqn - subs->freqn / 8 && f <= subs->freqmax) {
                  spin_lock_irqsave(&subs->lock, flags);
                  subs->freqm = f;
                  spin_unlock_irqrestore(&subs->lock, flags);
            }
      }

      return 0;
}

/* determine the number of frames in the next packet */
static int snd_usb_audio_next_packet_size(struct snd_usb_substream *subs)
{
      if (subs->fill_max)
            return subs->maxframesize;
      else {
            subs->phase = (subs->phase & 0xffff)
                  + (subs->freqm << subs->datainterval);
            return min(subs->phase >> 16, subs->maxframesize);
      }
}

/*
 * Prepare urb for streaming before playback starts or when paused.
 *
 * We don't have any data, so we send a frame of silence.
 */
static int prepare_nodata_playback_urb(struct snd_usb_substream *subs,
                               struct snd_pcm_runtime *runtime,
                               struct urb *urb)
{
      unsigned int i, offs, counts;
      struct snd_urb_ctx *ctx = urb->context;
      int stride = runtime->frame_bits >> 3;

      offs = 0;
      urb->dev = ctx->subs->dev;
      urb->number_of_packets = subs->packs_per_ms;
      for (i = 0; i < subs->packs_per_ms; ++i) {
            counts = snd_usb_audio_next_packet_size(subs);
            urb->iso_frame_desc[i].offset = offs * stride;
            urb->iso_frame_desc[i].length = counts * stride;
            offs += counts;
      }
      urb->transfer_buffer_length = offs * stride;
      memset(urb->transfer_buffer,
             subs->cur_audiofmt->format == SNDRV_PCM_FORMAT_U8 ? 0x80 : 0,
             offs * stride);
      return 0;
}

/*
 * prepare urb for playback data pipe
 *
 * Since a URB can handle only a single linear buffer, we must use double
 * buffering when the data to be transferred overflows the buffer boundary.
 * To avoid inconsistencies when updating hwptr_done, we use double buffering
 * for all URBs.
 */
static int prepare_playback_urb(struct snd_usb_substream *subs,
                        struct snd_pcm_runtime *runtime,
                        struct urb *urb)
{
      int i, stride, offs;
      unsigned int counts;
      unsigned long flags;
      int period_elapsed = 0;
      struct snd_urb_ctx *ctx = 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++) {
            counts = snd_usb_audio_next_packet_size(subs);
            /* 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_done += counts;
            if (subs->transfer_done >= runtime->period_size) {
                  subs->transfer_done -= runtime->period_size;
                  period_elapsed = 1;
                  if (subs->fmt_type == USB_FORMAT_TYPE_II) {
                        if (subs->transfer_done > 0) {
                              /* FIXME: fill-max mode is not
                               * supported yet */
                              offs -= subs->transfer_done;
                              counts -= subs->transfer_done;
                              urb->iso_frame_desc[i].length =
                                    counts * stride;
                              subs->transfer_done = 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;
                  }
            }
            /* finish at the frame boundary at/after the period boundary */
            if (period_elapsed &&
                (i & (subs->packs_per_ms - 1)) == subs->packs_per_ms - 1)
                  break;
      }
      if (subs->hwptr_done + offs > runtime->buffer_size) {
            /* err, the transferred area goes over buffer boundary. */
            unsigned int len = runtime->buffer_size - subs->hwptr_done;
            memcpy(urb->transfer_buffer,
                   runtime->dma_area + subs->hwptr_done * stride,
                   len * stride);
            memcpy(urb->transfer_buffer + len * stride,
                   runtime->dma_area,
                   (offs - len) * stride);
      } else {
            memcpy(urb->transfer_buffer,
                   runtime->dma_area + subs->hwptr_done * stride,
                   offs * stride);
      }
      subs->hwptr_done += offs;
      if (subs->hwptr_done >= runtime->buffer_size)
            subs->hwptr_done -= runtime->buffer_size;
      spin_unlock_irqrestore(&subs->lock, flags);
      urb->transfer_buffer_length = offs * stride;
      if (period_elapsed)
            snd_pcm_period_elapsed(subs->pcm_substream);
      return 0;
}

/*
 * process after playback data complete
 * - nothing to do
 */
static int retire_playback_urb(struct snd_usb_substream *subs,
                         struct snd_pcm_runtime *runtime,
                         struct urb *urb)
{
      return 0;
}


/*
 */
static struct snd_urb_ops audio_urb_ops[2] = {
      {
            .prepare =  prepare_nodata_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_nodata_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 snd_urb_ctx *ctx = urb->context;
      struct snd_usb_substream *subs = ctx->subs;
      struct snd_pcm_substream *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 snd_urb_ctx *ctx = urb->context;
      struct snd_usb_substream *subs = ctx->subs;
      struct snd_pcm_substream *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);
            }
      }
}


/* get the physical page pointer at the given offset */
static struct page *snd_pcm_get_vmalloc_page(struct snd_pcm_substream *subs,
                                   unsigned long offset)
{
      void *pageptr = subs->runtime->dma_area + offset;
      return vmalloc_to_page(pageptr);
}

/* allocate virtual buffer; may be called more than once */
static int snd_pcm_alloc_vmalloc_buffer(struct snd_pcm_substream *subs, size_t size)
{
      struct snd_pcm_runtime *runtime = subs->runtime;
      if (runtime->dma_area) {
            if (runtime->dma_bytes >= size)
                  return 0; /* already large enough */
            vfree(runtime->dma_area);
      }
      runtime->dma_area = vmalloc(size);
      if (! runtime->dma_area)
            return -ENOMEM;
      runtime->dma_bytes = size;
      return 0;
}

/* free virtual buffer; may be called more than once */
static int snd_pcm_free_vmalloc_buffer(struct snd_pcm_substream *subs)
{
      struct snd_pcm_runtime *runtime = subs->runtime;

      vfree(runtime->dma_area);
      runtime->dma_area = NULL;
      return 0;
}


/*
 * unlink active urbs.
 */
static int deactivate_urbs(struct snd_usb_substream *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)
                              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)
                                    usb_unlink_urb(u);
                              else
                                    usb_kill_urb(u);
                        }
                  }
            }
      }
      return 0;
}


static const char *usb_error_string(int err)
{
      switch (err) {
      case -ENODEV:
            return "no device";
      case -ENOENT:
            return "endpoint not enabled";
      case -EPIPE:
            return "endpoint stalled";
      case -ENOSPC:
            return "not enough bandwidth";
      case -ESHUTDOWN:
            return "device disabled";
      case -EHOSTUNREACH:
            return "device suspended";
#ifndef CONFIG_USB_EHCI_SPLIT_ISO
      case -ENOSYS:
            return "enable CONFIG_USB_EHCI_SPLIT_ISO to play through a hub";
#endif
      case -EINVAL:
      case -EAGAIN:
      case -EFBIG:
      case -EMSGSIZE:
            return "internal error";
      default:
            return "unknown error";
      }
}

/*
 * set up and start data/sync urbs
 */
static int start_urbs(struct snd_usb_substream *subs, struct snd_pcm_runtime *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++) {
            err = usb_submit_urb(subs->dataurb[i].urb, GFP_ATOMIC);
            if (err < 0) {
                  snd_printk(KERN_ERR "cannot submit datapipe "
                           "for urb %d, error %d: %s\n",
                           i, err, usb_error_string(err));
                  goto __error;
            }
            set_bit(i, &subs->active_mask);
      }
      if (subs->syncpipe) {
            for (i = 0; i < SYNC_URBS; i++) {
                  err = usb_submit_urb(subs->syncurb[i].urb, GFP_ATOMIC);
                  if (err < 0) {
                        snd_printk(KERN_ERR "cannot submit syncpipe "
                                 "for urb %d, error %d: %s\n",
                                 i, err, usb_error_string(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(struct snd_usb_substream *subs)
{
      unsigned long end_time = jiffies + msecs_to_jiffies(1000);
      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;
            schedule_timeout_uninterruptible(1);
      } while (time_before(jiffies, end_time));
      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(struct snd_pcm_substream *substream)
{
      struct snd_usb_substream *subs;
      snd_pcm_uframes_t hwptr_done;
      
      subs = (struct snd_usb_substream *)substream->runtime->private_data;
      spin_lock(&subs->lock);
      hwptr_done = subs->hwptr_done;
      spin_unlock(&subs->lock);
      return hwptr_done;
}


/*
 * start/stop playback substream
 */
static int snd_usb_pcm_playback_trigger(struct snd_pcm_substream *substream,
                              int cmd)
{
      struct snd_usb_substream *subs = substream->runtime->private_data;

      switch (cmd) {
      case SNDRV_PCM_TRIGGER_START:
      case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
            subs->ops.prepare = prepare_playback_urb;
            return 0;
      case SNDRV_PCM_TRIGGER_STOP:
            return deactivate_urbs(subs, 0, 0);
      case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
            subs->ops.prepare = prepare_nodata_playback_urb;
            return 0;
      default:
            return -EINVAL;
      }
}

/*
 * start/stop capture substream
 */
static int snd_usb_pcm_capture_trigger(struct snd_pcm_substream *substream,
                               int cmd)
{
      struct snd_usb_substream *subs = substream->runtime->private_data;

      switch (cmd) {
      case SNDRV_PCM_TRIGGER_START:
            subs->ops.retire = retire_capture_urb;
            return start_urbs(subs, substream->runtime);
      case SNDRV_PCM_TRIGGER_STOP:
            return deactivate_urbs(subs, 0, 0);
      case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
            subs->ops.retire = retire_paused_capture_urb;
            return 0;
      case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
            subs->ops.retire = retire_capture_urb;
            return 0;
      default:
            return -EINVAL;
      }
}


/*
 * release a urb data
 */
static void release_urb_ctx(struct snd_urb_ctx *u)
{
      if (u->urb) {
            if (u->buffer_size)
                  usb_buffer_free(u->subs->dev, u->buffer_size,
                              u->urb->transfer_buffer,
                              u->urb->transfer_dma);
            usb_free_urb(u->urb);
            u->urb = NULL;
      }
}

/*
 * release a substream
 */
static void release_substream_urbs(struct snd_usb_substream *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]);
      usb_buffer_free(subs->dev, SYNC_URBS * 4,
                  subs->syncbuf, subs->sync_dma);
      subs->syncbuf = NULL;
      subs->nurbs = 0;
}

/*
 * initialize a substream for plaback/capture
 */
static int init_substream_urbs(struct snd_usb_substream *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, packs_per_ms;

      /* 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;
      /* calculate max. frequency */
      if (subs->maxpacksize) {
            /* whatever fits into a max. size packet */
            maxsize = subs->maxpacksize;
            subs->freqmax = (maxsize / (frame_bits >> 3))
                        << (16 - subs->datainterval);
      } else {
            /* no max. packet size: just take 25% higher than nominal */
            subs->freqmax = subs->freqn + (subs->freqn >> 2);
            maxsize = ((subs->freqmax + 0xffff) * (frame_bits >> 3))
                        >> (16 - subs->datainterval);
      }
      subs->phase = 0;

      if (subs->fill_max)
            subs->curpacksize = subs->maxpacksize;
      else
            subs->curpacksize = maxsize;

      if (snd_usb_get_speed(subs->dev) == USB_SPEED_HIGH)
            packs_per_ms = 8 >> subs->datainterval;
      else
            packs_per_ms = 1;
      subs->packs_per_ms = packs_per_ms;

      if (is_playback) {
            urb_packs = nrpacks;
            urb_packs = max(urb_packs, (unsigned int)MIN_PACKS_URB);
            urb_packs = min(urb_packs, (unsigned int)MAX_PACKS);
      } else
            urb_packs = 1;
      urb_packs *= packs_per_ms;

      /* decide how many packets to be used */
      if (is_playback) {
            unsigned int minsize;
            /* determine how small a packet can be */
            minsize = (subs->freqn >> (16 - subs->datainterval))
                    * (frame_bits >> 3);
            /* with sync from device, assume it can be 12% lower */
            if (subs->syncpipe)
                  minsize -= minsize >> 3;
            minsize = max(minsize, 1u);
            total_packs = (period_bytes + minsize - 1) / minsize;
            /* round up to multiple of packs_per_ms */
            total_packs = (total_packs + packs_per_ms - 1)
                        & ~(packs_per_ms - 1);
            /* we need at least two URBs for queueing */
            if (total_packs < 2 * MIN_PACKS_URB * packs_per_ms)
                  total_packs = 2 * MIN_PACKS_URB * packs_per_ms;
      } else {
            total_packs = MAX_URBS * urb_packs;
      }
      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 * packs_per_ms) {
            /* 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++) {
            struct snd_urb_ctx *u = &subs->dataurb[i];
            u->index = i;
            u->subs = subs;
            u->packets = npacks[i];
            u->buffer_size = maxsize * u->packets;
            if (subs->fmt_type == USB_FORMAT_TYPE_II)
                  u->packets++; /* for transfer delimiter */
            u->urb = usb_alloc_urb(u->packets, GFP_KERNEL);
            if (! u->urb)
                  goto out_of_memory;
            u->urb->transfer_buffer =
                  usb_buffer_alloc(subs->dev, u->buffer_size, GFP_KERNEL,
                               &u->urb->transfer_dma);
            if (! u->urb->transfer_buffer)
                  goto out_of_memory;
            u->urb->pipe = subs->datapipe;
            u->urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP;
            u->urb->interval = 1 << subs->datainterval;
            u->urb->context = u;
            u->urb->complete = snd_complete_urb;
      }

      if (subs->syncpipe) {
            /* allocate and initialize sync urbs */
            subs->syncbuf = usb_buffer_alloc(subs->dev, SYNC_URBS * 4,
                                     GFP_KERNEL, &subs->sync_dma);
            if (! subs->syncbuf)
                  goto out_of_memory;
            for (i = 0; i < SYNC_URBS; i++) {
                  struct snd_urb_ctx *u = &subs->syncurb[i];
                  u->index = i;
                  u->subs = subs;
                  u->packets = 1;
                  u->urb = usb_alloc_urb(1, GFP_KERNEL);
                  if (! u->urb)
                        goto out_of_memory;
                  u->urb->transfer_buffer = subs->syncbuf + i * 4;
                  u->urb->transfer_dma = subs->sync_dma + i * 4;
                  u->urb->transfer_buffer_length = 4;
                  u->urb->pipe = subs->syncpipe;
                  u->urb->transfer_flags = URB_ISO_ASAP |
                                     URB_NO_TRANSFER_DMA_MAP;
                  u->urb->number_of_packets = 1;
                  u->urb->interval = 1 << subs->syncinterval;
                  u->urb->context = u;
                  u->urb->complete = snd_complete_sync_urb;
            }
      }
      return 0;

out_of_memory:
      release_substream_urbs(subs, 0);
      return -ENOMEM;
}


/*
 * find a matching audio format
 */
static struct audioformat *find_format(struct snd_usb_substream *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(struct snd_usb_substream *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) {
            if (usb_set_interface(subs->dev, subs->interface, 0) < 0) {
                  snd_printk(KERN_ERR "%d:%d:%d: return to setting 0 failed\n",
                        dev->devnum, fmt->iface, fmt->altsetting);
                  return -EIO;
            }
            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);
      if (snd_usb_get_speed(subs->dev) == USB_SPEED_HIGH &&
          get_endpoint(alts, 0)->bInterval >= 1 &&
          get_endpoint(alts, 0)->bInterval <= 4)
            subs->datainterval = get_endpoint(alts, 0)->bInterval - 1;
      else
            subs->datainterval = 0;
      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);
            if (get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
                get_endpoint(alts, 1)->bRefresh >= 1 &&
                get_endpoint(alts, 1)->bRefresh <= 9)
                  subs->syncinterval = get_endpoint(alts, 1)->bRefresh;
            else if (snd_usb_get_speed(subs->dev) == USB_SPEED_FULL)
                  subs->syncinterval = 1;
            else if (get_endpoint(alts, 1)->bInterval >= 1 &&
                   get_endpoint(alts, 1)->bInterval <= 16)
                  subs->syncinterval = get_endpoint(alts, 1)->bInterval - 1;
            else
                  subs->syncinterval = 3;
      }

      /* 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(struct snd_pcm_substream *substream,
                       struct snd_pcm_hw_params *hw_params)
{
      struct snd_usb_substream *subs = substream->runtime->private_data;
      struct audioformat *fmt;
      unsigned int channels, rate, format;
      int ret, changed;

      ret = snd_pcm_alloc_vmalloc_buffer(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 = 0x%x, rate = %d, channels = %d\n",
                     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(struct snd_pcm_substream *substream)
{
      struct snd_usb_substream *subs = substream->runtime->private_data;

      subs->cur_audiofmt = NULL;
      subs->cur_rate = 0;
      subs->period_bytes = 0;
      if (!subs->stream->chip->shutdown)
            release_substream_urbs(subs, 0);
      return snd_pcm_free_vmalloc_buffer(substream);
}

/*
 * prepare callback
 *
 * only a few subtle things...
 */
static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
{
      struct snd_pcm_runtime *runtime = substream->runtime;
      struct snd_usb_substream *subs = 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_done = 0;
      subs->transfer_done = 0;
      subs->phase = 0;

      /* clear urbs (to be sure) */
      deactivate_urbs(subs, 0, 1);
      wait_clear_urbs(subs);

      /* for playback, submit the URBs now; otherwise, the first hwptr_done
       * updates for all URBs would happen at the same time when starting */
      if (subs->direction == SNDRV_PCM_STREAM_PLAYBACK) {
            subs->ops.prepare = prepare_nodata_playback_urb;
            return start_urbs(subs, runtime);
      } else
            return 0;
}

static struct snd_pcm_hardware snd_usb_hardware =
{
      .info =                 SNDRV_PCM_INFO_MMAP |
                        SNDRV_PCM_INFO_MMAP_VALID |
                        SNDRV_PCM_INFO_BATCH |
                        SNDRV_PCM_INFO_INTERLEAVED |
                        SNDRV_PCM_INFO_BLOCK_TRANSFER |
                        SNDRV_PCM_INFO_PAUSE,
      .buffer_bytes_max =     1024 * 1024,
      .period_bytes_min =     64,
      .period_bytes_max =     512 * 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(struct snd_pcm_hw_params *params, struct audioformat *fp)
{
      struct snd_interval *it = hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
      struct snd_interval *ct = hw_param_interval(params, SNDRV_PCM_HW_PARAM_CHANNELS);
      struct snd_mask *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(struct snd_pcm_hw_params *params,
                  struct snd_pcm_hw_rule *rule)
{
      struct snd_usb_substream *subs = rule->private;
      struct list_head *p;
      struct snd_interval *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(struct snd_pcm_hw_params *params,
                      struct snd_pcm_hw_rule *rule)
{
      struct snd_usb_substream *subs = rule->private;
      struct list_head *p;
      struct snd_interval *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(struct snd_pcm_hw_params *params,
                    struct snd_pcm_hw_rule *rule)
{
      struct snd_usb_substream *subs = rule->private;
      struct list_head *p;
      struct snd_mask *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(struct snd_usb_substream *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;
            /* needs knot? */
            if (f->rates & SNDRV_PCM_RATE_KNOT)
                  goto __out;
      }
      /* 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;
}

/*
 *  If the device supports unusual bit rates, does the request meet these?
 */
static int snd_usb_pcm_check_knot(struct snd_pcm_runtime *runtime,
                          struct snd_usb_substream *subs)
{
      struct audioformat *fp;
      int count = 0, needs_knot = 0;
      int err;

      list_for_each_entry(fp, &subs->fmt_list, list) {
            if (fp->rates & SNDRV_PCM_RATE_CONTINUOUS)
                  return 0;
            count += fp->nr_rates;
            if (fp->rates & SNDRV_PCM_RATE_KNOT)
                  needs_knot = 1;
      }
      if (!needs_knot)
            return 0;

      subs->rate_list.count = count;
      subs->rate_list.list = kmalloc(sizeof(int) * count, GFP_KERNEL);
      subs->rate_list.mask = 0;
      count = 0;
      list_for_each_entry(fp, &subs->fmt_list, list) {
            int i;
            for (i = 0; i < fp->nr_rates; i++)
                  subs->rate_list.list[count++] = fp->rate_table[i];
      }
      err = snd_pcm_hw_constraint_list(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
                               &subs->rate_list);
      if (err < 0)
            return err;

      return 0;
}


/*
 * set up the runtime hardware information.
 */

static int setup_hw_info(struct snd_pcm_runtime *runtime, struct snd_usb_substream *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 */
      /* FIXME: high-speed mode allows 125us minimum period, but many parts
       * in the current code assume the 1ms period.
       */
      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;
            if ((err = snd_usb_pcm_check_knot(runtime, subs)) < 0)
                  return err;
      }
      return 0;
}

static int snd_usb_pcm_open(struct snd_pcm_substream *substream, int direction)
{
      struct snd_usb_stream *as = snd_pcm_substream_chip(substream);
      struct snd_pcm_runtime *runtime = substream->runtime;
      struct snd_usb_substream *subs = &as->substream[direction];

      subs->interface = -1;
      subs->format = 0;
      runtime->hw = snd_usb_hardware;
      runtime->private_data = subs;
      subs->pcm_substream = substream;
      return setup_hw_info(runtime, subs);
}

static int snd_usb_pcm_close(struct snd_pcm_substream *substream, int direction)
{
      struct snd_usb_stream *as = snd_pcm_substream_chip(substream);
      struct snd_usb_substream *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(struct snd_pcm_substream *substream)
{
      return snd_usb_pcm_open(substream, SNDRV_PCM_STREAM_PLAYBACK);
}

static int snd_usb_playback_close(struct snd_pcm_substream *substream)
{
      return snd_usb_pcm_close(substream, SNDRV_PCM_STREAM_PLAYBACK);
}

static int snd_usb_capture_open(struct snd_pcm_substream *substream)
{
      return snd_usb_pcm_open(substream, SNDRV_PCM_STREAM_CAPTURE);
}

static int snd_usb_capture_close(struct snd_pcm_substream *substream)
{
      return snd_usb_pcm_close(substream, SNDRV_PCM_STREAM_CAPTURE);
}

static struct snd_pcm_ops 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_playback_trigger,
      .pointer =  snd_usb_pcm_pointer,
      .page =           snd_pcm_get_vmalloc_page,
};

static struct snd_pcm_ops 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_capture_trigger,
      .pointer =  snd_usb_pcm_pointer,
      .page =           snd_pcm_get_vmalloc_page,
};



/*
 * 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 = kmemdup(data, size, GFP_KERNEL);
            if (!buf)
                  return -ENOMEM;
      }
      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);

#ifdef CONFIG_PM
static int usb_audio_suspend(struct usb_interface *intf, pm_message_t message);
static int usb_audio_resume(struct usb_interface *intf);
#else
#define usb_audio_suspend NULL
#define usb_audio_resume NULL
#endif

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


#if defined(CONFIG_PROC_FS) && defined(CONFIG_SND_VERBOSE_PROCFS)

/*
 * proc interface for list the supported pcm formats
 */
static void proc_dump_substream_formats(struct snd_usb_substream *subs, struct snd_info_buffer *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: 0x%x\n", 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(struct snd_usb_substream *subs, struct snd_info_buffer *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 (%#x.%04x)\n",
                      snd_usb_get_speed(subs->dev) == USB_SPEED_FULL
                      ? get_full_speed_hz(subs->freqm)
                      : get_high_speed_hz(subs->freqm),
                      subs->freqm >> 16, subs->freqm & 0xffff);
      } else {
            snd_iprintf(buffer, "  Status: Stop\n");
      }
}

static void proc_pcm_format_read(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
{
      struct snd_usb_stream *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(struct snd_usb_stream *stream)
{
      struct snd_info_entry *entry;
      char name[32];
      struct snd_card *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, proc_pcm_format_read);
}

#else

static inline void proc_pcm_format_add(struct snd_usb_stream *stream)
{
}

#endif

/*
 * initialize the substream instance.
 */

static void init_substream(struct snd_usb_stream *as, int stream, struct audioformat *fp)
{
      struct snd_usb_substream *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_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(struct snd_usb_substream *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);
      }
      kfree(subs->rate_list.list);
}


/*
 * free a usb stream instance
 */
static void snd_usb_audio_stream_free(struct snd_usb_stream *stream)
{
      free_substream(&stream->substream[0]);
      free_substream(&stream->substream[1]);
      list_del(&stream->list);
      kfree(stream);
}

static void snd_usb_audio_pcm_free(struct snd_pcm *pcm)
{
      struct snd_usb_stream *stream = pcm->private_data;
      if (stream) {
            stream->pcm = NULL;
            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(struct snd_usb_audio *chip, int stream, struct audioformat *fp)
{
      struct list_head *p;
      struct snd_usb_stream *as;
      struct snd_usb_substream *subs;
      struct snd_pcm *pcm;
      int err;

      list_for_each(p, &chip->pcm_list) {
            as = list_entry(p, struct snd_usb_stream, 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, struct snd_usb_stream, 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 = kzalloc(sizeof(*as), GFP_KERNEL);
      if (! as)
            return -ENOMEM;
      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 snd_usb_audio *chip, struct audioformat *fp)
{
      switch (chip->usb_id) {
      case USB_ID(0x0763, 0x2001): /* M-Audio Quattro: captured data only */
            if (fp->endpoint & USB_DIR_IN)
                  return 1;
            break;
      case USB_ID(0x0763, 0x2003): /* M-Audio Audiophile USB */
            if (device_setup[chip->index] == 0x00 ||
                fp->altsetting==1 || fp->altsetting==2 || fp->altsetting==3)
                  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 snd_usb_audio *chip, 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",
                      chip->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",
                           chip->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(chip, 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(chip, 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",
                           chip->dev->devnum, fp->iface,
                           fp->altsetting, sample_width, sample_bytes);
                  break;
            }
            break;
      case USB_AUDIO_FORMAT_PCM8:
            /* Dallas DS4201 workaround */
            if (chip->usb_id == USB_ID(0x04fa, 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",
                     chip->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 snd_usb_audio *chip, 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",
                           chip->dev->devnum, fp->iface, fp->altsetting);
            return -1;
      }

      if (nr_rates) {
            /*
             * build the rate table and bitmap flags
             */
            int r, idx;
            unsigned int nonzero_rates = 0;

            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 = combine_triple(&fmt[idx]);
                  /* C-Media CM6501 mislabels its 96 kHz altsetting */
                  if (rate == 48000 && nr_rates == 1 &&
                      chip->usb_id == USB_ID(0x0d8c, 0x0201) &&
                      fp->altsetting == 5 && fp->maxpacksize == 392)
                        rate = 96000;
                  fp->rate_table[r] = rate;
                  nonzero_rates |= rate;
                  if (rate < fp->rate_min)
                        fp->rate_min = rate;
                  else if (rate > fp->rate_max)
                        fp->rate_max = rate;
                  fp->rates |= snd_pcm_rate_to_rate_bit(rate);
            }
            if (!nonzero_rates) {
                  hwc_debug("All rates were zero. Skipping format!\n");
                  return -1;
            }
      } 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 snd_usb_audio *chip, 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...
             */
            switch (chip->usb_id) {

            case USB_ID(0x0763, 0x2003): /* M-Audio Audiophile USB */
                  if (device_setup[chip->index] == 0x00 && 
                      fp->altsetting == 6)
                        pcm_format = SNDRV_PCM_FORMAT_S16_BE;
                  else
                        pcm_format = SNDRV_PCM_FORMAT_S16_LE;
                  break;
            default:
                  pcm_format = SNDRV_PCM_FORMAT_S16_LE;
            }
      } else {
            pcm_format = parse_audio_format_i_type(chip, 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",
                     chip->dev->devnum, fp->iface, fp->altsetting, fp->channels);
            return -1;
      }
      return parse_audio_format_rates(chip, fp, fmt, 7);
}

/*
 * prase the format type II descriptor
 */
static int parse_audio_format_ii(struct snd_usb_audio *chip, 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",
                     chip->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(chip, fp, fmt, 8); /* fmt[8..] sample rates */
}

static int parse_audio_format(struct snd_usb_audio *chip, 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(chip, fp, format, fmt);
            break;
      case USB_FORMAT_TYPE_II:
            err = parse_audio_format_ii(chip, fp, format, fmt);
            break;
      default:
            snd_printd(KERN_INFO "%d:%u:%d : format type %d is not supported yet\n",
                     chip->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/audigy 2 nx/zs */
      /* extigy apparently supports sample rates other than 48k
       * but not in ordinary way.  so we enable only 48k atm.
       */
      if (chip->usb_id == USB_ID(0x041e, 0x3000) ||
          chip->usb_id == USB_ID(0x041e, 0x3020) ||
          chip->usb_id == USB_ID(0x041e, 0x3061)) {
            if (fmt[3] == USB_FORMAT_TYPE_I &&
                fp->rates != SNDRV_PCM_RATE_48000 &&
                fp->rates != SNDRV_PCM_RATE_96000)
                  return -1;
      }
#endif
      return 0;
}

static int audiophile_skip_setting_quirk(struct snd_usb_audio *chip,
                               int iface, int altno);
static int parse_audio_endpoints(struct snd_usb_audio *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;
      
            /* audiophile usb: skip altsets incompatible with device_setup
             */
            if (chip->usb_id == USB_ID(0x0763, 0x2003) && 
                audiophile_skip_setting_quirk(chip, iface_no, altno))
                  continue;

            /* 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_WARNING "%d:%u:%d : no or invalid"
                           " class specific endpoint descriptor\n",
                           dev->devnum, iface_no, altno);
                  csep = NULL;
            }

            fp = kzalloc(sizeof(*fp), GFP_KERNEL);
            if (! fp) {
                  snd_printk(KERN_ERR "cannot malloc\n");
                  return -ENOMEM;
            }

            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;
            fp->maxpacksize = le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize);
            if (snd_usb_get_speed(dev) == USB_SPEED_HIGH)
                  fp->maxpacksize = (((fp->maxpacksize >> 11) & 3) + 1)
                              * (fp->maxpacksize & 0x7ff);
            fp->attributes = csep ? csep[3] : 0;

            /* some quirks for attributes here */

            switch (chip->usb_id) {
            case USB_ID(0x0a92, 0x0053): /* AudioTrak Optoplay */
                  /* Optoplay sets the sample rate attribute although
                   * it seems not supporting it in fact.
                   */
                  fp->attributes &= ~EP_CS_ATTR_SAMPLE_RATE;
                  break;
            case USB_ID(0x041e, 0x3020): /* Creative SB Audigy 2 NX */
            case USB_ID(0x0763, 0x2003): /* M-Audio Audiophile USB */
                  /* doesn't set the sample rate attribute, but supports it */
                  fp->attributes |= EP_CS_ATTR_SAMPLE_RATE;
                  break;
            case USB_ID(0x047f, 0x0ca1): /* plantronics headset */
            case USB_ID(0x077d, 0x07af): /* Griffin iMic (note that there is
                                    an older model 77d:223) */
            /*
             * plantronics headset and Griffin iMic have set adaptive-in
             * although it's really not...
             */
                  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;
                  break;
            }

            /* ok, let's parse further... */
            if (parse_audio_format(chip, 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, altno, 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)
{
      int idx;
      struct snd_usb_stream *as;
      struct snd_usb_substream *subs;

      as = list_entry(head, struct snd_usb_stream, list);
      for (idx = 0; idx < 2; idx++) {
            subs = &as->substream[idx];
            if (!subs->num_formats)
                  return;
            release_substream_urbs(subs, 1);
            subs->interface = -1;
      }
}

/*
 * parse audio control descriptor and create pcm/midi streams
 */
static int snd_usb_create_streams(struct snd_usb_audio *chip, int ctrlif)
{
      struct usb_device *dev = chip->dev;
      struct usb_host_interface *host_iface;
      struct usb_interface *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 (snd_usb_get_speed(dev) == USB_SPEED_LOW) {
                  snd_printk(KERN_ERR "low speed audio streaming not supported\n");
                  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(struct snd_usb_audio *chip,
                             struct usb_interface *iface,
                             const struct snd_usb_audio_quirk *quirk)
{
      struct audioformat *fp;
      struct usb_host_interface *alts;
      int stream, err;
      unsigned *rate_table = NULL;

      fp = kmemdup(quirk->data, sizeof(*fp), GFP_KERNEL);
      if (! fp) {
            snd_printk(KERN_ERR "cannot memdup\n");
            return -ENOMEM;
      }
      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_audio_quirk(struct snd_usb_audio *chip,
                               struct usb_interface *iface,
                               const struct snd_usb_audio_quirk *quirk)
{
      struct usb_host_interface *alts;
      struct usb_interface_descriptor *altsd;
      int err;

      alts = &iface->altsetting[0];
      altsd = get_iface_desc(alts);
      err = parse_audio_endpoints(chip, altsd->bInterfaceNumber);
      if (err < 0) {
            snd_printk(KERN_ERR "cannot setup if %d: error %d\n",
                     altsd->bInterfaceNumber, err);
            return err;
      }
      /* reset the current interface */
      usb_set_interface(chip->dev, altsd->bInterfaceNumber, 0);
      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(struct snd_usb_audio *chip,
                           struct usb_interface *iface,
                           const struct snd_usb_audio_quirk *quirk)
{
      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 struct snd_usb_midi_endpoint_info ua700_ep = {
                  .out_cables = 0x0003,
                  .in_cables  = 0x0003
            };
            static const struct snd_usb_audio_quirk ua700_quirk = {
                  .type = QUIRK_MIDI_FIXED_ENDPOINT,
                  .data = &ua700_ep
            };
            static const struct snd_usb_midi_endpoint_info ua25_ep = {
                  .out_cables = 0x0001,
                  .in_cables  = 0x0001
            };
            static const struct snd_usb_audio_quirk ua25_quirk = {
                  .type = QUIRK_MIDI_FIXED_ENDPOINT,
                  .data = &ua25_ep
            };
            if (chip->usb_id == USB_ID(0x0582, 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(struct snd_usb_audio *chip,
                         struct usb_interface *iface,
                         const struct snd_usb_audio_quirk *quirk)
{
      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] != USB_DT_CS_INTERFACE ||
          altsd->bNumEndpoints != 1)
            return -ENXIO;

      fp = kmemdup(&ua1000_format, sizeof(*fp), GFP_KERNEL);
      if (!fp)
            return -ENOMEM;

      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;
}

/*
 * Create a stream for an Edirol UA-101 interface.
 * Copy, paste and modify from Edirol UA-1000
 */
static int create_ua101_quirk(struct snd_usb_audio *chip,
                         struct usb_interface *iface,
                         const struct snd_usb_audio_quirk *quirk)
{
      static const struct audioformat ua101_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 != 18 || alts->extra[1] != USB_DT_CS_INTERFACE ||
          altsd->bNumEndpoints != 1)
            return -ENXIO;

      fp = kmemdup(&ua101_format, sizeof(*fp), GFP_KERNEL);
      if (!fp)
            return -ENOMEM;

      fp->channels = alts->extra[11];
      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[15]);

      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(struct snd_usb_audio *chip,
                        struct usb_interface *iface,
                        const struct snd_usb_audio_quirk *quirk);

/*
 * handle the quirks for the contained interfaces
 */
static int create_composite_quirk(struct snd_usb_audio *chip,
                          struct usb_interface *iface,
                          const struct snd_usb_audio_quirk *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;
}

static int ignore_interface_quirk(struct snd_usb_audio *chip,
                          struct usb_interface *iface,
                          const struct snd_usb_audio_quirk *quirk)
{
      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;
}

static int snd_usb_audigy2nx_boot_quirk(struct usb_device *dev)
{
      u8 buf = 1;

      snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), 0x2a,
                  USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_OTHER,
                  0, 0, &buf, 1, 1000);
      if (buf == 0) {
            snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), 0x29,
                        USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_OTHER,
                        1, 2000, NULL, 0, 1000);
            return -ENODEV;
      }
      return 0;
}

/*
 * C-Media CM106/CM106+ have four 16-bit internal registers that are nicely
 * documented in the device's data sheet.
 */
static int snd_usb_cm106_write_int_reg(struct usb_device *dev, int reg, u16 value)
{
      u8 buf[4];
      buf[0] = 0x20;
      buf[1] = value & 0xff;
      buf[2] = (value >> 8) & 0xff;
      buf[3] = reg;
      return snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), USB_REQ_SET_CONFIGURATION,
                         USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_ENDPOINT,
                         0, 0, &buf, 4, 1000);
}

static int snd_usb_cm106_boot_quirk(struct usb_device *dev)
{
      /*
       * Enable line-out driver mode, set headphone source to front
       * channels, enable stereo mic.
       */
      return snd_usb_cm106_write_int_reg(dev, 2, 0x8004);
}


/*
 * Setup quirks
 */
#define AUDIOPHILE_SET              0x01 /* if set, parse device_setup */
#define AUDIOPHILE_SET_DTS              0x02 /* if set, enable DTS Digital Output */
#define AUDIOPHILE_SET_96K              0x04 /* 48-96KHz rate if set, 8-48KHz otherwise */
#define AUDIOPHILE_SET_24B          0x08 /* 24bits sample if set, 16bits otherwise */
#define AUDIOPHILE_SET_DI           0x10 /* if set, enable Digital Input */
#define AUDIOPHILE_SET_MASK         0x1F /* bit mask for setup value */
#define AUDIOPHILE_SET_24B_48K_DI   0x19 /* value for 24bits+48KHz+Digital Input */
#define AUDIOPHILE_SET_24B_48K_NOTDI      0x09 /* value for 24bits+48KHz+No Digital Input */
#define AUDIOPHILE_SET_16B_48K_DI   0x11 /* value for 16bits+48KHz+Digital Input */
#define AUDIOPHILE_SET_16B_48K_NOTDI      0x01 /* value for 16bits+48KHz+No Digital Input */

static int audiophile_skip_setting_quirk(struct snd_usb_audio *chip,
                               int iface, int altno)
{
      /* Reset ALL ifaces to 0 altsetting.
       * Call it for every possible altsetting of every interface.
       */
      usb_set_interface(chip->dev, iface, 0);

      if (device_setup[chip->index] & AUDIOPHILE_SET) {
            if ((device_setup[chip->index] & AUDIOPHILE_SET_DTS)
                && altno != 6)
                  return 1; /* skip this altsetting */
            if ((device_setup[chip->index] & AUDIOPHILE_SET_96K)
                && altno != 1)
                  return 1; /* skip this altsetting */
            if ((device_setup[chip->index] & AUDIOPHILE_SET_MASK) ==
                AUDIOPHILE_SET_24B_48K_DI && altno != 2)
                  return 1; /* skip this altsetting */
            if ((device_setup[chip->index] & AUDIOPHILE_SET_MASK) ==
                AUDIOPHILE_SET_24B_48K_NOTDI && altno != 3)
                  return 1; /* skip this altsetting */
            if ((device_setup[chip->index] & AUDIOPHILE_SET_MASK) ==
                AUDIOPHILE_SET_16B_48K_DI && altno != 4)
                  return 1; /* skip this altsetting */
            if ((device_setup[chip->index] & AUDIOPHILE_SET_MASK) ==
                AUDIOPHILE_SET_16B_48K_NOTDI && altno != 5)
                  return 1; /* skip this altsetting */
      }     
      return 0; /* keep this altsetting */
}

/*
 * 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(struct snd_usb_audio *chip,
                        struct usb_interface *iface,
                        const struct snd_usb_audio_quirk *quirk)
{
      typedef int (*quirk_func_t)(struct snd_usb_audio *, struct usb_interface *,
                            const struct snd_usb_audio_quirk *);
      static const quirk_func_t quirk_funcs[] = {
            [QUIRK_IGNORE_INTERFACE] = ignore_interface_quirk,
            [QUIRK_COMPOSITE] = create_composite_quirk,
            [QUIRK_MIDI_STANDARD_INTERFACE] = snd_usb_create_midi_interface,
            [QUIRK_MIDI_FIXED_ENDPOINT] = snd_usb_create_midi_interface,
            [QUIRK_MIDI_YAMAHA] = snd_usb_create_midi_interface,
            [QUIRK_MIDI_MIDIMAN] = snd_usb_create_midi_interface,
            [QUIRK_MIDI_NOVATION] = snd_usb_create_midi_interface,
            [QUIRK_MIDI_RAW] = snd_usb_create_midi_interface,
            [QUIRK_MIDI_EMAGIC] = snd_usb_create_midi_interface,
            [QUIRK_MIDI_CME] = snd_usb_create_midi_interface,
            [QUIRK_AUDIO_STANDARD_INTERFACE] = create_standard_audio_quirk,
            [QUIRK_AUDIO_FIXED_ENDPOINT] = create_fixed_stream_quirk,
            [QUIRK_AUDIO_EDIROL_UA700_UA25] = create_ua700_ua25_quirk,
            [QUIRK_AUDIO_EDIROL_UA1000] = create_ua1000_quirk,
            [QUIRK_AUDIO_EDIROL_UA101] = create_ua101_quirk,
      };

      if (quirk->type < QUIRK_TYPE_COUNT) {
            return quirk_funcs[quirk->type](chip, iface, quirk);
      } else {
            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(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
{
      struct snd_usb_audio *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(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
{
      struct snd_usb_audio *chip = entry->private_data;
      if (! chip->shutdown)
            snd_iprintf(buffer, "%04x:%04x\n", 
                      USB_ID_VENDOR(chip->usb_id),
                      USB_ID_PRODUCT(chip->usb_id));
}

static void snd_usb_audio_create_proc(struct snd_usb_audio *chip)
{
      struct snd_info_entry *entry;
      if (! snd_card_proc_new(chip->card, "usbbus", &entry))
            snd_info_set_text_ops(entry, chip, proc_audio_usbbus_read);
      if (! snd_card_proc_new(chip->card, "usbid", &entry))
            snd_info_set_text_ops(entry, chip, 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(struct snd_usb_audio *chip)
{
      usb_chip[chip->index] = NULL;
      kfree(chip);
      return 0;
}

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


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

      *rchip = NULL;

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

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

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

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

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

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

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

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

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

      strlcat(card->longname,
            snd_usb_get_speed(dev) == USB_SPEED_LOW ? ", low speed" :
            snd_usb_get_speed(dev) == USB_SPEED_FULL ? ", full speed" :
            ", high speed",
            sizeof(card->longname));

      snd_usb_audio_create_proc(chip);

      *rchip = chip;
      return 0;
}


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

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

      if (quirk && quirk->ifnum >= 0 && ifnum != quirk->ifnum)
            goto __err_val;

      /* SB Extigy needs special boot-up sequence */
      /* if more models come, this will go to the quirk list. */
      if (id == USB_ID(0x041e, 0x3000)) {
            if (snd_usb_extigy_boot_quirk(dev, intf) < 0)
                  goto __err_val;
      }
      /* SB Audigy 2 NX needs its own boot-up magic, too */
      if (id == USB_ID(0x041e, 0x3020)) {
            if (snd_usb_audigy2nx_boot_quirk(dev) < 0)
                  goto __err_val;
      }

      /* C-Media CM106 / Turtle Beach Audio Advantage Roadie */
      if (id == USB_ID(0x10f5, 0x0200)) {
            if (snd_usb_cm106_boot_quirk(dev) < 0)
                  goto __err_val;
      }

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

      /* check whether it's already registered */
      chip = NULL;
      mutex_lock(&register_mutex);
      for (i = 0; i < SNDRV_CARDS; i++) {
            if (usb_chip[i] && usb_chip[i]->dev == dev) {
                  if (usb_chip[i]->shutdown) {
                        snd_printk(KERN_ERR "USB device is in the shutdown state, cannot create a card instance\n");
                        goto __error;
                  }
                  chip = usb_chip[i];
                  break;
            }
      }
      if (! chip) {
            /* it's a fresh one.
             * now look for an empty slot and create a new card instance
             */
            for (i = 0; i < SNDRV_CARDS; i++)
                  if (enable[i] && ! usb_chip[i] &&
                      (vid[i] == -1 || vid[i] == USB_ID_VENDOR(id)) &&
                      (pid[i] == -1 || pid[i] == USB_ID_PRODUCT(id))) {
                        if (snd_usb_audio_create(dev, i, quirk, &chip) < 0) {
                              goto __error;
                        }
                        snd_card_set_dev(chip->card, &intf->dev);
                        break;
                  }
            if (! chip) {
                  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++;
      mutex_unlock(&register_mutex);
      return chip;

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

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

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

      chip = ptr;
      card = chip->card;
      mutex_lock(&register_mutex);
      chip->shutdown = 1;
      chip->num_interfaces--;
      if (chip->num_interfaces <= 0) {
            snd_card_disconnect(card);
            /* release the pcm resources */
            list_for_each(p, &chip->pcm_list) {
                  snd_usb_stream_disconnect(p);
            }
            /* release the midi resources */
            list_for_each(p, &chip->midi_list) {
                  snd_usbmidi_disconnect(p);
            }
            /* release mixer resources */
            list_for_each(p, &chip->mixer_list) {
                  snd_usb_mixer_disconnect(p);
            }
            mutex_unlock(&register_mutex);
            snd_card_free_when_closed(card);
      } else {
            mutex_unlock(&register_mutex);
      }
}

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

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

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

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

      return 0;
}

static int usb_audio_resume(struct usb_interface *intf)
{
      struct snd_usb_audio *chip = dev_get_drvdata(&intf->dev);

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

      snd_power_change_state(chip->card, SNDRV_CTL_POWER_D0);

      return 0;
}
#endif            /* CONFIG_PM */

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;
      }
      return usb_register(&usb_audio_driver);
}


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

module_init(snd_usb_audio_init);
module_exit(snd_usb_audio_cleanup);

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