/*
   *   (Tentative) USB Audio Driver for ALSA
   *
   *   Mixer control 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
   *
   */

  /*
   * TODOs, for both the mixer and the streaming interfaces:
   *
   *  - support for UAC2 effect units
   *  - support for graphical equalizers
   *  - RANGE and MEM set commands (UAC2)
   *  - RANGE and MEM interrupt dispatchers (UAC2)
   *  - audio channel clustering (UAC2)
   *  - audio sample rate converter units (UAC2)
   *  - proper handling of clock multipliers (UAC2)
   *  - dispatch clock change notifications (UAC2)
   *  	- stop PCM streams which use a clock that became invalid
   *  	- stop PCM streams which use a clock selector that has changed
   *  	- parse available sample rates again when clock sources changed
   */

  #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/usb/audio.h>

  #include <linux/usb/audio-v2.h>

  #include <sound/core.h>
  #include <sound/control.h>

  #include <sound/hwdep.h>

  #include <sound/info.h>

  #include <sound/tlv.h>

  
  #include "usbaudio.h"

  #include "mixer.h"

  #include "helper.h"

  #include "mixer_quirks.h"

  #include "power.h"

  #define MAX_ID_ELEMS	256

  struct usb_audio_term {
  	int id;
  	int type;
  	int channels;
  	unsigned int chconfig;
  	int name;
  };
  
  struct usbmix_name_map;

  struct mixer_build {
  	struct snd_usb_audio *chip;

  	struct usb_mixer_interface *mixer;

  	unsigned char *buffer;
  	unsigned int buflen;

  	DECLARE_BITMAP(unitbitmap, MAX_ID_ELEMS);

  	struct usb_audio_term oterm;

  	const struct usbmix_name_map *map;

  	const struct usbmix_selector_map *selector_map;

  };

  /*E-mu 0202/0404/0204 eXtension Unit(XU) control*/

  enum {
  	USB_XU_CLOCK_RATE 		= 0xe301,
  	USB_XU_CLOCK_SOURCE		= 0xe302,
  	USB_XU_DIGITAL_IO_STATUS	= 0xe303,
  	USB_XU_DEVICE_OPTIONS		= 0xe304,
  	USB_XU_DIRECT_MONITORING	= 0xe305,
  	USB_XU_METERING			= 0xe306
  };
  enum {
  	USB_XU_CLOCK_SOURCE_SELECTOR = 0x02,	/* clock source*/
  	USB_XU_CLOCK_RATE_SELECTOR = 0x03,	/* clock rate */
  	USB_XU_DIGITAL_FORMAT_SELECTOR = 0x01,	/* the spdif format */
  	USB_XU_SOFT_LIMIT_SELECTOR = 0x03	/* soft limiter */
  };

  
  /*
   * manual mapping of mixer names
   * if the mixer topology is too complicated and the parsed names are
   * ambiguous, add the entries in usbmixer_maps.c.
   */

  #include "mixer_maps.c"

  static const struct usbmix_name_map *
  find_map(struct mixer_build *state, int unitid, int control)

  {

  	const struct usbmix_name_map *p = state->map;

  	if (!p)
  		return NULL;

  
  	for (p = state->map; p->id; p++) {

  		if (p->id == unitid &&
  		    (!control || !p->control || control == p->control))
  			return p;

  	}

  	return NULL;

  }

  /* get the mapped name if the unit matches */
  static int
  check_mapped_name(const struct usbmix_name_map *p, char *buf, int buflen)

  {

  	if (!p || !p->name)
  		return 0;

  	buflen--;
  	return strlcpy(buf, p->name, buflen);
  }
  
  /* check whether the control should be ignored */
  static inline int
  check_ignored_ctl(const struct usbmix_name_map *p)
  {
  	if (!p || p->name || p->dB)

  		return 0;

  	return 1;
  }
  
  /* dB mapping */
  static inline void check_mapped_dB(const struct usbmix_name_map *p,
  				   struct usb_mixer_elem_info *cval)
  {
  	if (p && p->dB) {
  		cval->dBmin = p->dB->min;
  		cval->dBmax = p->dB->max;

  		cval->initialized = 1;

  	}

  }

  /* get the mapped selector source name */

  static int check_mapped_selector_name(struct mixer_build *state, int unitid,

  				      int index, char *buf, int buflen)
  {
  	const struct usbmix_selector_map *p;
  
  	if (! state->selector_map)
  		return 0;
  	for (p = state->selector_map; p->id; p++) {
  		if (p->id == unitid && index < p->count)
  			return strlcpy(buf, p->names[index], buflen);
  	}
  	return 0;
  }

  /*
   * find an audio control unit with the given unit id
   */

  static void *find_audio_control_unit(struct mixer_build *state, unsigned char unit)

  {

  	/* we just parse the header */
  	struct uac_feature_unit_descriptor *hdr = NULL;
  
  	while ((hdr = snd_usb_find_desc(state->buffer, state->buflen, hdr,
  					USB_DT_CS_INTERFACE)) != NULL) {
  		if (hdr->bLength >= 4 &&
  		    hdr->bDescriptorSubtype >= UAC_INPUT_TERMINAL &&
  		    hdr->bDescriptorSubtype <= UAC2_SAMPLE_RATE_CONVERTER &&
  		    hdr->bUnitID == unit)
  			return hdr;

  	}

  	return NULL;
  }

  /*
   * copy a string with the given id
   */

  static int snd_usb_copy_string_desc(struct mixer_build *state, int index, char *buf, int maxlen)

  {
  	int len = usb_string(state->chip->dev, index, buf, maxlen - 1);
  	buf[len] = 0;
  	return len;
  }
  
  /*
   * convert from the byte/word on usb descriptor to the zero-based integer
   */

  static int convert_signed_value(struct usb_mixer_elem_info *cval, int val)

  {
  	switch (cval->val_type) {
  	case USB_MIXER_BOOLEAN:
  		return !!val;
  	case USB_MIXER_INV_BOOLEAN:
  		return !val;
  	case USB_MIXER_U8:
  		val &= 0xff;
  		break;
  	case USB_MIXER_S8:
  		val &= 0xff;
  		if (val >= 0x80)
  			val -= 0x100;
  		break;
  	case USB_MIXER_U16:
  		val &= 0xffff;
  		break;
  	case USB_MIXER_S16:
  		val &= 0xffff;
  		if (val >= 0x8000)
  			val -= 0x10000;
  		break;
  	}
  	return val;
  }
  
  /*
   * convert from the zero-based int to the byte/word for usb descriptor
   */

  static int convert_bytes_value(struct usb_mixer_elem_info *cval, int val)

  {
  	switch (cval->val_type) {
  	case USB_MIXER_BOOLEAN:
  		return !!val;
  	case USB_MIXER_INV_BOOLEAN:
  		return !val;
  	case USB_MIXER_S8:
  	case USB_MIXER_U8:
  		return val & 0xff;
  	case USB_MIXER_S16:
  	case USB_MIXER_U16:
  		return val & 0xffff;
  	}
  	return 0; /* not reached */
  }

  static int get_relative_value(struct usb_mixer_elem_info *cval, int val)

  {
  	if (! cval->res)
  		cval->res = 1;
  	if (val < cval->min)
  		return 0;

  	else if (val >= cval->max)
  		return (cval->max - cval->min + cval->res - 1) / cval->res;

  	else
  		return (val - cval->min) / cval->res;
  }

  static int get_abs_value(struct usb_mixer_elem_info *cval, int val)

  {
  	if (val < 0)
  		return cval->min;
  	if (! cval->res)
  		cval->res = 1;
  	val *= cval->res;
  	val += cval->min;
  	if (val > cval->max)
  		return cval->max;
  	return val;
  }
  
  
  /*
   * retrieve a mixer value
   */

  static int get_ctl_value_v1(struct usb_mixer_elem_info *cval, int request, int validx, int *value_ret)

  {

  	struct snd_usb_audio *chip = cval->mixer->chip;

  	unsigned char buf[2];
  	int val_len = cval->val_type >= USB_MIXER_S16 ? 2 : 1;
  	int timeout = 10;

  	int err;

  	err = snd_usb_autoresume(cval->mixer->chip);
  	if (err < 0)
  		return -EIO;

  	while (timeout-- > 0) {

  		if (snd_usb_ctl_msg(chip->dev, usb_rcvctrlpipe(chip->dev, 0), request,

  				    USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,

  				    validx, snd_usb_ctrl_intf(chip) | (cval->id << 8),

  				    buf, val_len) >= val_len) {

  			*value_ret = convert_signed_value(cval, snd_usb_combine_bytes(buf, val_len));

  			snd_usb_autosuspend(cval->mixer->chip);

  			return 0;
  		}
  	}

  	snd_usb_autosuspend(cval->mixer->chip);

  	snd_printdd(KERN_ERR "cannot get ctl value: req = %#x, wValue = %#x, wIndex = %#x, type = %d
  ",

  		    request, validx, snd_usb_ctrl_intf(chip) | (cval->id << 8), cval->val_type);

  	return -EINVAL;
  }

  static int get_ctl_value_v2(struct usb_mixer_elem_info *cval, int request, int validx, int *value_ret)
  {

  	struct snd_usb_audio *chip = cval->mixer->chip;

  	unsigned char buf[2 + 3*sizeof(__u16)]; /* enough space for one range */

  	unsigned char *val;

  	int ret, size;

  	__u8 bRequest;

  	if (request == UAC_GET_CUR) {
  		bRequest = UAC2_CS_CUR;
  		size = sizeof(__u16);
  	} else {
  		bRequest = UAC2_CS_RANGE;
  		size = sizeof(buf);
  	}
  
  	memset(buf, 0, sizeof(buf));

  	ret = snd_usb_autoresume(chip) ? -EIO : 0;
  	if (ret)
  		goto error;

  	ret = snd_usb_ctl_msg(chip->dev, usb_rcvctrlpipe(chip->dev, 0), bRequest,

  			      USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,

  			      validx, snd_usb_ctrl_intf(chip) | (cval->id << 8),

  			      buf, size);

  	snd_usb_autosuspend(chip);

  
  	if (ret < 0) {

  error:

  		snd_printk(KERN_ERR "cannot get ctl value: req = %#x, wValue = %#x, wIndex = %#x, type = %d
  ",

  			   request, validx, snd_usb_ctrl_intf(chip) | (cval->id << 8), cval->val_type);

  		return ret;
  	}

  	/* FIXME: how should we handle multiple triplets here? */

  	switch (request) {
  	case UAC_GET_CUR:
  		val = buf;
  		break;
  	case UAC_GET_MIN:
  		val = buf + sizeof(__u16);
  		break;
  	case UAC_GET_MAX:
  		val = buf + sizeof(__u16) * 2;
  		break;
  	case UAC_GET_RES:
  		val = buf + sizeof(__u16) * 3;
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	*value_ret = convert_signed_value(cval, snd_usb_combine_bytes(val, sizeof(__u16)));
  
  	return 0;
  }
  
  static int get_ctl_value(struct usb_mixer_elem_info *cval, int request, int validx, int *value_ret)
  {
  	return (cval->mixer->protocol == UAC_VERSION_1) ?
  		get_ctl_value_v1(cval, request, validx, value_ret) :
  		get_ctl_value_v2(cval, request, validx, value_ret);
  }

  static int get_cur_ctl_value(struct usb_mixer_elem_info *cval, int validx, int *value)

  {

  	return get_ctl_value(cval, UAC_GET_CUR, validx, value);

  }
  
  /* channel = 0: master, 1 = first channel */

  static inline int get_cur_mix_raw(struct usb_mixer_elem_info *cval,
  				  int channel, int *value)

  {

  	return get_ctl_value(cval, UAC_GET_CUR, (cval->control << 8) | channel, value);

  }

  static int get_cur_mix_value(struct usb_mixer_elem_info *cval,
  			     int channel, int index, int *value)
  {
  	int err;
  
  	if (cval->cached & (1 << channel)) {
  		*value = cval->cache_val[index];
  		return 0;
  	}
  	err = get_cur_mix_raw(cval, channel, value);
  	if (err < 0) {
  		if (!cval->mixer->ignore_ctl_error)

  			snd_printd(KERN_ERR "cannot get current value for control %d ch %d: err = %d
  ",

  				   cval->control, channel, err);
  		return err;
  	}
  	cval->cached |= 1 << channel;
  	cval->cache_val[index] = *value;
  	return 0;
  }

  /*
   * set a mixer value
   */

  int snd_usb_mixer_set_ctl_value(struct usb_mixer_elem_info *cval,
  				int request, int validx, int value_set)

  {

  	struct snd_usb_audio *chip = cval->mixer->chip;

  	unsigned char buf[2];

  	int val_len, err, timeout = 10;

  
  	if (cval->mixer->protocol == UAC_VERSION_1) {
  		val_len = cval->val_type >= USB_MIXER_S16 ? 2 : 1;
  	} else { /* UAC_VERSION_2 */
  		/* audio class v2 controls are always 2 bytes in size */
  		val_len = sizeof(__u16);
  
  		/* FIXME */
  		if (request != UAC_SET_CUR) {
  			snd_printdd(KERN_WARNING "RANGE setting not yet supported
  ");
  			return -EINVAL;
  		}
  
  		request = UAC2_CS_CUR;
  	}

  
  	value_set = convert_bytes_value(cval, value_set);
  	buf[0] = value_set & 0xff;
  	buf[1] = (value_set >> 8) & 0xff;

  	err = snd_usb_autoresume(chip);
  	if (err < 0)
  		return -EIO;

  	while (timeout-- > 0)

  		if (snd_usb_ctl_msg(chip->dev,
  				    usb_sndctrlpipe(chip->dev, 0), request,

  				    USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_OUT,

  				    validx, snd_usb_ctrl_intf(chip) | (cval->id << 8),

  				    buf, val_len) >= 0) {

  			snd_usb_autosuspend(chip);

  			return 0;

  		}
  	snd_usb_autosuspend(chip);

  	snd_printdd(KERN_ERR "cannot set ctl value: req = %#x, wValue = %#x, wIndex = %#x, type = %d, data = %#x/%#x
  ",

  		    request, validx, snd_usb_ctrl_intf(chip) | (cval->id << 8), cval->val_type, buf[0], buf[1]);

  	return -EINVAL;
  }

  static int set_cur_ctl_value(struct usb_mixer_elem_info *cval, int validx, int value)

  {

  	return snd_usb_mixer_set_ctl_value(cval, UAC_SET_CUR, validx, value);

  }

  static int set_cur_mix_value(struct usb_mixer_elem_info *cval, int channel,
  			     int index, int value)

  {

  	int err;

  	unsigned int read_only = (channel == 0) ?
  		cval->master_readonly :
  		cval->ch_readonly & (1 << (channel - 1));
  
  	if (read_only) {
  		snd_printdd(KERN_INFO "%s(): channel %d of control %d is read_only
  ",
  			    __func__, channel, cval->control);
  		return 0;
  	}

  	err = snd_usb_mixer_set_ctl_value(cval, UAC_SET_CUR, (cval->control << 8) | channel,

  			    value);
  	if (err < 0)
  		return err;
  	cval->cached |= 1 << channel;
  	cval->cache_val[index] = value;
  	return 0;

  }

  /*
   * TLV callback for mixer volume controls
   */
  static int mixer_vol_tlv(struct snd_kcontrol *kcontrol, int op_flag,
  			 unsigned int size, unsigned int __user *_tlv)
  {
  	struct usb_mixer_elem_info *cval = kcontrol->private_data;

  	DECLARE_TLV_DB_MINMAX(scale, 0, 0);

  
  	if (size < sizeof(scale))
  		return -ENOMEM;

  	scale[2] = cval->dBmin;
  	scale[3] = cval->dBmax;

  	if (copy_to_user(_tlv, scale, sizeof(scale)))
  		return -EFAULT;
  	return 0;
  }

  
  /*
   * parser routines begin here...
   */

  static int parse_audio_unit(struct mixer_build *state, int unitid);

  
  
  /*
   * check if the input/output channel routing is enabled on the given bitmap.
   * used for mixer unit parser
   */
  static int check_matrix_bitmap(unsigned char *bmap, int ich, int och, int num_outs)
  {
  	int idx = ich * num_outs + och;
  	return bmap[idx >> 3] & (0x80 >> (idx & 7));
  }
  
  
  /*
   * add an alsa control element
   * search and increment the index until an empty slot is found.
   *
   * if failed, give up and free the control instance.
   */

  int snd_usb_mixer_add_control(struct usb_mixer_interface *mixer,
  			      struct snd_kcontrol *kctl)

  {

  	struct usb_mixer_elem_info *cval = kctl->private_data;

  	int err;

  	while (snd_ctl_find_id(mixer->chip->card, &kctl->id))

  		kctl->id.index++;

  	if ((err = snd_ctl_add(mixer->chip->card, kctl)) < 0) {

  		snd_printd(KERN_ERR "cannot add control (err = %d)
  ", err);

  		return err;

  	}

  	cval->elem_id = &kctl->id;

  	cval->next_id_elem = mixer->id_elems[cval->id];
  	mixer->id_elems[cval->id] = cval;

  	return 0;

  }
  
  
  /*
   * get a terminal name string
   */
  
  static struct iterm_name_combo {
  	int type;
  	char *name;
  } iterm_names[] = {
  	{ 0x0300, "Output" },
  	{ 0x0301, "Speaker" },
  	{ 0x0302, "Headphone" },
  	{ 0x0303, "HMD Audio" },
  	{ 0x0304, "Desktop Speaker" },
  	{ 0x0305, "Room Speaker" },
  	{ 0x0306, "Com Speaker" },
  	{ 0x0307, "LFE" },
  	{ 0x0600, "External In" },
  	{ 0x0601, "Analog In" },
  	{ 0x0602, "Digital In" },
  	{ 0x0603, "Line" },
  	{ 0x0604, "Legacy In" },
  	{ 0x0605, "IEC958 In" },
  	{ 0x0606, "1394 DA Stream" },
  	{ 0x0607, "1394 DV Stream" },
  	{ 0x0700, "Embedded" },
  	{ 0x0701, "Noise Source" },
  	{ 0x0702, "Equalization Noise" },
  	{ 0x0703, "CD" },
  	{ 0x0704, "DAT" },
  	{ 0x0705, "DCC" },
  	{ 0x0706, "MiniDisk" },
  	{ 0x0707, "Analog Tape" },
  	{ 0x0708, "Phonograph" },
  	{ 0x0709, "VCR Audio" },
  	{ 0x070a, "Video Disk Audio" },
  	{ 0x070b, "DVD Audio" },
  	{ 0x070c, "TV Tuner Audio" },
  	{ 0x070d, "Satellite Rec Audio" },
  	{ 0x070e, "Cable Tuner Audio" },
  	{ 0x070f, "DSS Audio" },
  	{ 0x0710, "Radio Receiver" },
  	{ 0x0711, "Radio Transmitter" },
  	{ 0x0712, "Multi-Track Recorder" },
  	{ 0x0713, "Synthesizer" },
  	{ 0 },
  };

  static int get_term_name(struct mixer_build *state, struct usb_audio_term *iterm,

  			 unsigned char *name, int maxlen, int term_only)
  {
  	struct iterm_name_combo *names;
  
  	if (iterm->name)
  		return snd_usb_copy_string_desc(state, iterm->name, name, maxlen);
  
  	/* virtual type - not a real terminal */
  	if (iterm->type >> 16) {
  		if (term_only)
  			return 0;
  		switch (iterm->type >> 16) {

  		case UAC_SELECTOR_UNIT:

  			strcpy(name, "Selector"); return 8;

  		case UAC1_PROCESSING_UNIT:

  			strcpy(name, "Process Unit"); return 12;

  		case UAC1_EXTENSION_UNIT:

  			strcpy(name, "Ext Unit"); return 8;

  		case UAC_MIXER_UNIT:

  			strcpy(name, "Mixer"); return 5;
  		default:
  			return sprintf(name, "Unit %d", iterm->id);
  		}
  	}
  
  	switch (iterm->type & 0xff00) {
  	case 0x0100:
  		strcpy(name, "PCM"); return 3;
  	case 0x0200:
  		strcpy(name, "Mic"); return 3;
  	case 0x0400:
  		strcpy(name, "Headset"); return 7;
  	case 0x0500:
  		strcpy(name, "Phone"); return 5;
  	}
  
  	for (names = iterm_names; names->type; names++)
  		if (names->type == iterm->type) {
  			strcpy(name, names->name);
  			return strlen(names->name);
  		}
  	return 0;
  }
  
  
  /*
   * parse the source unit recursively until it reaches to a terminal
   * or a branched unit.
   */

  static int check_input_term(struct mixer_build *state, int id, struct usb_audio_term *term)

  {

  	int err;

  	void *p1;

  
  	memset(term, 0, sizeof(*term));
  	while ((p1 = find_audio_control_unit(state, id)) != NULL) {

  		unsigned char *hdr = p1;

  		term->id = id;

  		switch (hdr[2]) {

  		case UAC_INPUT_TERMINAL:

  			if (state->mixer->protocol == UAC_VERSION_1) {
  				struct uac_input_terminal_descriptor *d = p1;
  				term->type = le16_to_cpu(d->wTerminalType);
  				term->channels = d->bNrChannels;
  				term->chconfig = le16_to_cpu(d->wChannelConfig);
  				term->name = d->iTerminal;
  			} else { /* UAC_VERSION_2 */
  				struct uac2_input_terminal_descriptor *d = p1;
  				term->type = le16_to_cpu(d->wTerminalType);
  				term->channels = d->bNrChannels;
  				term->chconfig = le32_to_cpu(d->bmChannelConfig);
  				term->name = d->iTerminal;

  
  				/* call recursively to get the clock selectors */
  				err = check_input_term(state, d->bCSourceID, term);
  				if (err < 0)
  					return err;

  			}

  			return 0;

  		case UAC_FEATURE_UNIT: {
  			/* the header is the same for v1 and v2 */
  			struct uac_feature_unit_descriptor *d = p1;

  			id = d->bSourceID;

  			break; /* continue to parse */

  		}
  		case UAC_MIXER_UNIT: {
  			struct uac_mixer_unit_descriptor *d = p1;
  			term->type = d->bDescriptorSubtype << 16; /* virtual type */
  			term->channels = uac_mixer_unit_bNrChannels(d);
  			term->chconfig = uac_mixer_unit_wChannelConfig(d, state->mixer->protocol);
  			term->name = uac_mixer_unit_iMixer(d);

  			return 0;

  		}

  		case UAC_SELECTOR_UNIT:
  		case UAC2_CLOCK_SELECTOR: {

  			struct uac_selector_unit_descriptor *d = p1;

  			/* call recursively to retrieve the channel info */

  			if (check_input_term(state, d->baSourceID[0], term) < 0)

  				return -ENODEV;

  			term->type = d->bDescriptorSubtype << 16; /* virtual type */

  			term->id = id;

  			term->name = uac_selector_unit_iSelector(d);

  			return 0;

  		}

  		case UAC1_PROCESSING_UNIT:
  		case UAC1_EXTENSION_UNIT: {

  			struct uac_processing_unit_descriptor *d = p1;
  			if (d->bNrInPins) {
  				id = d->baSourceID[0];

  				break; /* continue to parse */
  			}

  			term->type = d->bDescriptorSubtype << 16; /* virtual type */
  			term->channels = uac_processing_unit_bNrChannels(d);
  			term->chconfig = uac_processing_unit_wChannelConfig(d, state->mixer->protocol);
  			term->name = uac_processing_unit_iProcessing(d, state->mixer->protocol);

  			return 0;

  		}

  		case UAC2_CLOCK_SOURCE: {
  			struct uac_clock_source_descriptor *d = p1;
  			term->type = d->bDescriptorSubtype << 16; /* virtual type */
  			term->id = id;
  			term->name = d->iClockSource;
  			return 0;
  		}

  		default:
  			return -ENODEV;
  		}
  	}
  	return -ENODEV;
  }
  
  
  /*
   * Feature Unit
   */
  
  /* feature unit control information */
  struct usb_feature_control_info {
  	const char *name;
  	unsigned int type;	/* control type (mute, volume, etc.) */
  };
  
  static struct usb_feature_control_info audio_feature_info[] = {

  	{ "Mute",			USB_MIXER_INV_BOOLEAN },
  	{ "Volume",			USB_MIXER_S16 },

  	{ "Tone Control - Bass",	USB_MIXER_S8 },
  	{ "Tone Control - Mid",		USB_MIXER_S8 },
  	{ "Tone Control - Treble",	USB_MIXER_S8 },
  	{ "Graphic Equalizer",		USB_MIXER_S8 }, /* FIXME: not implemeted yet */

  	{ "Auto Gain Control",		USB_MIXER_BOOLEAN },
  	{ "Delay Control",		USB_MIXER_U16 },
  	{ "Bass Boost",			USB_MIXER_BOOLEAN },
  	{ "Loudness",			USB_MIXER_BOOLEAN },
  	/* UAC2 specific */
  	{ "Input Gain Control",		USB_MIXER_U16 },
  	{ "Input Gain Pad Control",	USB_MIXER_BOOLEAN },
  	{ "Phase Inverter Control",	USB_MIXER_BOOLEAN },

  };
  
  
  /* private_free callback */

  static void usb_mixer_elem_free(struct snd_kcontrol *kctl)

  {

  	kfree(kctl->private_data);
  	kctl->private_data = NULL;

  }
  
  
  /*
   * interface to ALSA control for feature/mixer units
   */

  /* volume control quirks */
  static void volume_control_quirks(struct usb_mixer_elem_info *cval,
  				  struct snd_kcontrol *kctl)
  {
  	switch (cval->mixer->chip->usb_id) {
  	case USB_ID(0x0471, 0x0101):
  	case USB_ID(0x0471, 0x0104):
  	case USB_ID(0x0471, 0x0105):
  	case USB_ID(0x0672, 0x1041):
  	/* quirk for UDA1321/N101.
  	 * note that detection between firmware 2.1.1.7 (N101)
  	 * and later 2.1.1.21 is not very clear from datasheets.
  	 * I hope that the min value is -15360 for newer firmware --jk
  	 */
  		if (!strcmp(kctl->id.name, "PCM Playback Volume") &&
  		    cval->min == -15616) {
  			snd_printk(KERN_INFO
  				 "set volume quirk for UDA1321/N101 chip
  ");
  			cval->max = -256;
  		}
  		break;
  
  	case USB_ID(0x046d, 0x09a4):
  		if (!strcmp(kctl->id.name, "Mic Capture Volume")) {
  			snd_printk(KERN_INFO
  				"set volume quirk for QuickCam E3500
  ");
  			cval->min = 6080;
  			cval->max = 8768;
  			cval->res = 192;
  		}
  		break;
  
  	case USB_ID(0x046d, 0x0808):
  	case USB_ID(0x046d, 0x0809):

  	case USB_ID(0x046d, 0x081d): /* HD Webcam c510 */

  	case USB_ID(0x046d, 0x0991):
  	/* Most audio usb devices lie about volume resolution.
  	 * Most Logitech webcams have res = 384.
  	 * Proboly there is some logitech magic behind this number --fishor
  	 */
  		if (!strcmp(kctl->id.name, "Mic Capture Volume")) {
  			snd_printk(KERN_INFO
  				"set resolution quirk: cval->res = 384
  ");
  			cval->res = 384;
  		}
  		break;
  
  	}
  }

  /*
   * retrieve the minimum and maximum values for the specified control
   */

  static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval,
  				   int default_min, struct snd_kcontrol *kctl)

  {
  	/* for failsafe */
  	cval->min = default_min;
  	cval->max = cval->min + 1;
  	cval->res = 1;

  	cval->dBmin = cval->dBmax = 0;

  
  	if (cval->val_type == USB_MIXER_BOOLEAN ||
  	    cval->val_type == USB_MIXER_INV_BOOLEAN) {
  		cval->initialized = 1;
  	} else {
  		int minchn = 0;
  		if (cval->cmask) {
  			int i;
  			for (i = 0; i < MAX_CHANNELS; i++)
  				if (cval->cmask & (1 << i)) {
  					minchn = i + 1;
  					break;
  				}
  		}

  		if (get_ctl_value(cval, UAC_GET_MAX, (cval->control << 8) | minchn, &cval->max) < 0 ||
  		    get_ctl_value(cval, UAC_GET_MIN, (cval->control << 8) | minchn, &cval->min) < 0) {

  			snd_printd(KERN_ERR "%d:%d: cannot get min/max values for control %d (id %d)
  ",

  				   cval->id, snd_usb_ctrl_intf(cval->mixer->chip), cval->control, cval->id);

  			return -EINVAL;
  		}

  		if (get_ctl_value(cval, UAC_GET_RES, (cval->control << 8) | minchn, &cval->res) < 0) {

  			cval->res = 1;
  		} else {
  			int last_valid_res = cval->res;
  
  			while (cval->res > 1) {

  				if (snd_usb_mixer_set_ctl_value(cval, UAC_SET_RES,
  								(cval->control << 8) | minchn, cval->res / 2) < 0)

  					break;
  				cval->res /= 2;
  			}

  			if (get_ctl_value(cval, UAC_GET_RES, (cval->control << 8) | minchn, &cval->res) < 0)

  				cval->res = last_valid_res;
  		}
  		if (cval->res == 0)
  			cval->res = 1;

  
  		/* Additional checks for the proper resolution
  		 *
  		 * Some devices report smaller resolutions than actually
  		 * reacting.  They don't return errors but simply clip
  		 * to the lower aligned value.
  		 */
  		if (cval->min + cval->res < cval->max) {
  			int last_valid_res = cval->res;
  			int saved, test, check;

  			get_cur_mix_raw(cval, minchn, &saved);

  			for (;;) {
  				test = saved;
  				if (test < cval->max)
  					test += cval->res;
  				else
  					test -= cval->res;
  				if (test < cval->min || test > cval->max ||

  				    set_cur_mix_value(cval, minchn, 0, test) ||
  				    get_cur_mix_raw(cval, minchn, &check)) {

  					cval->res = last_valid_res;
  					break;
  				}
  				if (test == check)
  					break;
  				cval->res *= 2;
  			}

  			set_cur_mix_value(cval, minchn, 0, saved);

  		}

  		cval->initialized = 1;
  	}

  	if (kctl)
  		volume_control_quirks(cval, kctl);

  	/* USB descriptions contain the dB scale in 1/256 dB unit
  	 * while ALSA TLV contains in 1/100 dB unit
  	 */
  	cval->dBmin = (convert_signed_value(cval, cval->min) * 100) / 256;
  	cval->dBmax = (convert_signed_value(cval, cval->max) * 100) / 256;
  	if (cval->dBmin > cval->dBmax) {
  		/* something is wrong; assume it's either from/to 0dB */
  		if (cval->dBmin < 0)
  			cval->dBmax = 0;
  		else if (cval->dBmin > 0)
  			cval->dBmin = 0;
  		if (cval->dBmin > cval->dBmax) {
  			/* totally crap, return an error */
  			return -EINVAL;
  		}
  	}

  	return 0;
  }

  #define get_min_max(cval, def)	get_min_max_with_quirks(cval, def, NULL)

  
  /* get a feature/mixer unit info */

  static int mixer_ctl_feature_info(struct snd_kcontrol *kcontrol, struct snd_ctl_elem_info *uinfo)

  {

  	struct usb_mixer_elem_info *cval = kcontrol->private_data;

  
  	if (cval->val_type == USB_MIXER_BOOLEAN ||
  	    cval->val_type == USB_MIXER_INV_BOOLEAN)
  		uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
  	else
  		uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
  	uinfo->count = cval->channels;
  	if (cval->val_type == USB_MIXER_BOOLEAN ||
  	    cval->val_type == USB_MIXER_INV_BOOLEAN) {
  		uinfo->value.integer.min = 0;
  		uinfo->value.integer.max = 1;
  	} else {

  		if (!cval->initialized) {

  			get_min_max_with_quirks(cval, 0, kcontrol);

  			if (cval->initialized && cval->dBmin >= cval->dBmax) {
  				kcontrol->vd[0].access &= 
  					~(SNDRV_CTL_ELEM_ACCESS_TLV_READ |
  					  SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK);
  				snd_ctl_notify(cval->mixer->chip->card,
  					       SNDRV_CTL_EVENT_MASK_INFO,
  					       &kcontrol->id);
  			}
  		}

  		uinfo->value.integer.min = 0;

  		uinfo->value.integer.max =
  			(cval->max - cval->min + cval->res - 1) / cval->res;

  	}
  	return 0;
  }
  
  /* get the current value from feature/mixer unit */

  static int mixer_ctl_feature_get(struct snd_kcontrol *kcontrol, struct snd_ctl_elem_value *ucontrol)

  {

  	struct usb_mixer_elem_info *cval = kcontrol->private_data;

  	int c, cnt, val, err;

  	ucontrol->value.integer.value[0] = cval->min;

  	if (cval->cmask) {
  		cnt = 0;
  		for (c = 0; c < MAX_CHANNELS; c++) {

  			if (!(cval->cmask & (1 << c)))
  				continue;
  			err = get_cur_mix_value(cval, c + 1, cnt, &val);
  			if (err < 0)
  				return cval->mixer->ignore_ctl_error ? 0 : err;
  			val = get_relative_value(cval, val);
  			ucontrol->value.integer.value[cnt] = val;
  			cnt++;

  		}

  		return 0;

  	} else {
  		/* master channel */

  		err = get_cur_mix_value(cval, 0, 0, &val);
  		if (err < 0)
  			return cval->mixer->ignore_ctl_error ? 0 : err;

  		val = get_relative_value(cval, val);
  		ucontrol->value.integer.value[0] = val;
  	}
  	return 0;
  }
  
  /* put the current value to feature/mixer unit */

  static int mixer_ctl_feature_put(struct snd_kcontrol *kcontrol, struct snd_ctl_elem_value *ucontrol)

  {

  	struct usb_mixer_elem_info *cval = kcontrol->private_data;

  	int c, cnt, val, oval, err;
  	int changed = 0;
  
  	if (cval->cmask) {
  		cnt = 0;
  		for (c = 0; c < MAX_CHANNELS; c++) {

  			if (!(cval->cmask & (1 << c)))
  				continue;
  			err = get_cur_mix_value(cval, c + 1, cnt, &oval);
  			if (err < 0)
  				return cval->mixer->ignore_ctl_error ? 0 : err;
  			val = ucontrol->value.integer.value[cnt];
  			val = get_abs_value(cval, val);
  			if (oval != val) {
  				set_cur_mix_value(cval, c + 1, cnt, val);
  				changed = 1;

  			}

  			cnt++;

  		}
  	} else {
  		/* master channel */

  		err = get_cur_mix_value(cval, 0, 0, &oval);

  		if (err < 0)

  			return cval->mixer->ignore_ctl_error ? 0 : err;

  		val = ucontrol->value.integer.value[0];
  		val = get_abs_value(cval, val);
  		if (val != oval) {

  			set_cur_mix_value(cval, 0, 0, val);

  			changed = 1;
  		}
  	}
  	return changed;
  }

  static struct snd_kcontrol_new usb_feature_unit_ctl = {

  	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
  	.name = "", /* will be filled later manually */
  	.info = mixer_ctl_feature_info,
  	.get = mixer_ctl_feature_get,
  	.put = mixer_ctl_feature_put,
  };

  /* the read-only variant */
  static struct snd_kcontrol_new usb_feature_unit_ctl_ro = {
  	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
  	.name = "", /* will be filled later manually */
  	.info = mixer_ctl_feature_info,
  	.get = mixer_ctl_feature_get,
  	.put = NULL,
  };

  /* This symbol is exported in order to allow the mixer quirks to
   * hook up to the standard feature unit control mechanism */
  struct snd_kcontrol_new *snd_usb_feature_unit_ctl = &usb_feature_unit_ctl;

  
  /*
   * build a feature control
   */

  static size_t append_ctl_name(struct snd_kcontrol *kctl, const char *str)
  {
  	return strlcat(kctl->id.name, str, sizeof(kctl->id.name));
  }

  static void build_feature_ctl(struct mixer_build *state, void *raw_desc,

  			      unsigned int ctl_mask, int control,

  			      struct usb_audio_term *iterm, int unitid,

  			      int readonly_mask)

  {

  	struct uac_feature_unit_descriptor *desc = raw_desc;

  	unsigned int len = 0;
  	int mapped_name = 0;

  	int nameid = uac_feature_unit_iFeature(desc);

  	struct snd_kcontrol *kctl;
  	struct usb_mixer_elem_info *cval;

  	const struct usbmix_name_map *map;

  	unsigned int range;

  
  	control++; /* change from zero-based to 1-based value */

  	if (control == UAC_FU_GRAPHIC_EQUALIZER) {

  		/* FIXME: not supported yet */
  		return;
  	}

  	map = find_map(state, unitid, control);
  	if (check_ignored_ctl(map))

  		return;

  	cval = kzalloc(sizeof(*cval), GFP_KERNEL);

  	if (! cval) {
  		snd_printk(KERN_ERR "cannot malloc kcontrol
  ");
  		return;
  	}

  	cval->mixer = state->mixer;

  	cval->id = unitid;
  	cval->control = control;
  	cval->cmask = ctl_mask;
  	cval->val_type = audio_feature_info[control-1].type;

  	if (ctl_mask == 0) {

  		cval->channels = 1;	/* master channel */

  		cval->master_readonly = readonly_mask;
  	} else {

  		int i, c = 0;
  		for (i = 0; i < 16; i++)
  			if (ctl_mask & (1 << i))
  				c++;
  		cval->channels = c;

  		cval->ch_readonly = readonly_mask;

  	}

  	/* if all channels in the mask are marked read-only, make the control
  	 * read-only. set_cur_mix_value() will check the mask again and won't
  	 * issue write commands to read-only channels. */
  	if (cval->channels == readonly_mask)

  		kctl = snd_ctl_new1(&usb_feature_unit_ctl_ro, cval);
  	else
  		kctl = snd_ctl_new1(&usb_feature_unit_ctl, cval);

  	if (! kctl) {
  		snd_printk(KERN_ERR "cannot malloc kcontrol
  ");
  		kfree(cval);
  		return;
  	}
  	kctl->private_free = usb_mixer_elem_free;

  	len = check_mapped_name(map, kctl->id.name, sizeof(kctl->id.name));

  	mapped_name = len != 0;
  	if (! len && nameid)

  		len = snd_usb_copy_string_desc(state, nameid,
  				kctl->id.name, sizeof(kctl->id.name));

  	/* get min/max values */
  	get_min_max_with_quirks(cval, 0, kctl);

  	switch (control) {

  	case UAC_FU_MUTE:
  	case UAC_FU_VOLUME:

  		/* determine the control name.  the rule is:
  		 * - if a name id is given in descriptor, use it.
  		 * - if the connected input can be determined, then use the name
  		 *   of terminal type.
  		 * - if the connected output can be determined, use it.
  		 * - otherwise, anonymous name.
  		 */
  		if (! len) {
  			len = get_term_name(state, iterm, kctl->id.name, sizeof(kctl->id.name), 1);
  			if (! len)
  				len = get_term_name(state, &state->oterm, kctl->id.name, sizeof(kctl->id.name), 1);
  			if (! len)
  				len = snprintf(kctl->id.name, sizeof(kctl->id.name),
  					       "Feature %d", unitid);
  		}
  		/* determine the stream direction:
  		 * if the connected output is USB stream, then it's likely a
  		 * capture stream.  otherwise it should be playback (hopefully :)
  		 */
  		if (! mapped_name && ! (state->oterm.type >> 16)) {
  			if ((state->oterm.type & 0xff00) == 0x0100) {

  				len = append_ctl_name(kctl, " Capture");

  			} else {

  				len = append_ctl_name(kctl, " Playback");

  			}
  		}

  		append_ctl_name(kctl, control == UAC_FU_MUTE ?

  				" Switch" : " Volume");

  		if (control == UAC_FU_VOLUME) {

  			check_mapped_dB(map, cval);

  			if (cval->dBmin < cval->dBmax || !cval->initialized) {

  				kctl->tlv.c = mixer_vol_tlv;
  				kctl->vd[0].access |= 
  					SNDRV_CTL_ELEM_ACCESS_TLV_READ |
  					SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;
  			}

  		}

  		break;
  
  	default:
  		if (! len)
  			strlcpy(kctl->id.name, audio_feature_info[control-1].name,
  				sizeof(kctl->id.name));
  		break;
  	}

  	range = (cval->max - cval->min) / cval->res;
  	/* Are there devices with volume range more than 255? I use a bit more
  	 * to be sure. 384 is a resolution magic number found on Logitech
  	 * devices. It will definitively catch all buggy Logitech devices.
  	 */
  	if (range > 384) {
  		snd_printk(KERN_WARNING "usb_audio: Warning! Unlikely big "
  			   "volume range (=%u), cval->res is probably wrong.",
  			   range);
  		snd_printk(KERN_WARNING "usb_audio: [%d] FU [%s] ch = %d, "
  			   "val = %d/%d/%d", cval->id,
  			   kctl->id.name, cval->channels,
  			   cval->min, cval->max, cval->res);
  	}

  	snd_printdd(KERN_INFO "[%d] FU [%s] ch = %d, val = %d/%d/%d
  ",
  		    cval->id, kctl->id.name, cval->channels, cval->min, cval->max, cval->res);

  	snd_usb_mixer_add_control(state->mixer, kctl);

  }
  
  
  
  /*
   * parse a feature unit
   *

   * most of controls are defined here.

   */

  static int parse_audio_feature_unit(struct mixer_build *state, int unitid, void *_ftr)

  {
  	int channels, i, j;

  	struct usb_audio_term iterm;

  	unsigned int master_bits, first_ch_bits;
  	int err, csize;

  	struct uac_feature_unit_descriptor *hdr = _ftr;
  	__u8 *bmaControls;
  
  	if (state->mixer->protocol == UAC_VERSION_1) {
  		csize = hdr->bControlSize;

  		if (!csize) {
  			snd_printdd(KERN_ERR "usbaudio: unit %u: "
  				    "invalid bControlSize == 0
  ", unitid);
  			return -EINVAL;
  		}

  		channels = (hdr->bLength - 7) / csize - 1;
  		bmaControls = hdr->bmaControls;
  	} else {
  		struct uac2_feature_unit_descriptor *ftr = _ftr;
  		csize = 4;

  		channels = (hdr->bLength - 6) / 4 - 1;

  		bmaControls = ftr->bmaControls;
  	}

  	if (hdr->bLength < 7 || !csize || hdr->bLength < 7 + csize) {

  		snd_printk(KERN_ERR "usbaudio: unit %u: invalid UAC_FEATURE_UNIT descriptor
  ", unitid);

  		return -EINVAL;
  	}
  
  	/* parse the source unit */

  	if ((err = parse_audio_unit(state, hdr->bSourceID)) < 0)

  		return err;
  
  	/* determine the input source type and name */

  	if (check_input_term(state, hdr->bSourceID, &iterm) < 0)

  		return -EINVAL;

  	master_bits = snd_usb_combine_bytes(bmaControls, csize);

  	/* master configuration quirks */
  	switch (state->chip->usb_id) {
  	case USB_ID(0x08bb, 0x2702):
  		snd_printk(KERN_INFO
  			   "usbmixer: master volume quirk for PCM2702 chip
  ");
  		/* disable non-functional volume control */

  		master_bits &= ~UAC_CONTROL_BIT(UAC_FU_VOLUME);

  		break;
  	}

  	if (channels > 0)

  		first_ch_bits = snd_usb_combine_bytes(bmaControls + csize, csize);

  	else
  		first_ch_bits = 0;

  
  	if (state->mixer->protocol == UAC_VERSION_1) {
  		/* check all control types */
  		for (i = 0; i < 10; i++) {
  			unsigned int ch_bits = 0;
  			for (j = 0; j < channels; j++) {
  				unsigned int mask = snd_usb_combine_bytes(bmaControls + csize * (j+1), csize);
  				if (mask & (1 << i))
  					ch_bits |= (1 << j);
  			}
  			/* audio class v1 controls are never read-only */
  			if (ch_bits & 1) /* the first channel must be set (for ease of programming) */
  				build_feature_ctl(state, _ftr, ch_bits, i, &iterm, unitid, 0);
  			if (master_bits & (1 << i))
  				build_feature_ctl(state, _ftr, 0, i, &iterm, unitid, 0);
  		}
  	} else { /* UAC_VERSION_2 */

  		for (i = 0; i < ARRAY_SIZE(audio_feature_info); i++) {

  			unsigned int ch_bits = 0;
  			unsigned int ch_read_only = 0;
  
  			for (j = 0; j < channels; j++) {
  				unsigned int mask = snd_usb_combine_bytes(bmaControls + csize * (j+1), csize);

  				if (uac2_control_is_readable(mask, i)) {

  					ch_bits |= (1 << j);

  					if (!uac2_control_is_writeable(mask, i))

  						ch_read_only |= (1 << j);
  				}
  			}

  			/* NOTE: build_feature_ctl() will mark the control read-only if all channels
  			 * are marked read-only in the descriptors. Otherwise, the control will be
  			 * reported as writeable, but the driver will not actually issue a write
  			 * command for read-only channels */

  			if (ch_bits & 1) /* the first channel must be set (for ease of programming) */

  				build_feature_ctl(state, _ftr, ch_bits, i, &iterm, unitid, ch_read_only);

  			if (uac2_control_is_readable(master_bits, i))

  				build_feature_ctl(state, _ftr, 0, i, &iterm, unitid,

  						  !uac2_control_is_writeable(master_bits, i));

  		}

  	}
  
  	return 0;
  }
  
  
  /*
   * Mixer Unit
   */
  
  /*
   * build a mixer unit control
   *
   * the callbacks are identical with feature unit.
   * input channel number (zero based) is given in control field instead.
   */

  static void build_mixer_unit_ctl(struct mixer_build *state,
  				 struct uac_mixer_unit_descriptor *desc,

  				 int in_pin, int in_ch, int unitid,

  				 struct usb_audio_term *iterm)

  {

  	struct usb_mixer_elem_info *cval;

  	unsigned int num_outs = uac_mixer_unit_bNrChannels(desc);

  	unsigned int i, len;

  	struct snd_kcontrol *kctl;

  	const struct usbmix_name_map *map;

  	map = find_map(state, unitid, 0);
  	if (check_ignored_ctl(map))

  		return;

  	cval = kzalloc(sizeof(*cval), GFP_KERNEL);

  	if (! cval)
  		return;

  	cval->mixer = state->mixer;

  	cval->id = unitid;
  	cval->control = in_ch + 1; /* based on 1 */
  	cval->val_type = USB_MIXER_S16;
  	for (i = 0; i < num_outs; i++) {

  		if (check_matrix_bitmap(uac_mixer_unit_bmControls(desc, state->mixer->protocol), in_ch, i, num_outs)) {

  			cval->cmask |= (1 << i);
  			cval->channels++;
  		}
  	}
  
  	/* get min/max values */
  	get_min_max(cval, 0);
  
  	kctl = snd_ctl_new1(&usb_feature_unit_ctl, cval);
  	if (! kctl) {
  		snd_printk(KERN_ERR "cannot malloc kcontrol
  ");
  		kfree(cval);
  		return;
  	}
  	kctl->private_free = usb_mixer_elem_free;

  	len = check_mapped_name(map, kctl->id.name, sizeof(kctl->id.name));

  	if (! len)
  		len = get_term_name(state, iterm, kctl->id.name, sizeof(kctl->id.name), 0);
  	if (! len)
  		len = sprintf(kctl->id.name, "Mixer Source %d", in_ch + 1);

  	append_ctl_name(kctl, " Volume");

  
  	snd_printdd(KERN_INFO "[%d] MU [%s] ch = %d, val = %d/%d
  ",
  		    cval->id, kctl->id.name, cval->channels, cval->min, cval->max);

  	snd_usb_mixer_add_control(state->mixer, kctl);

  }
  
  
  /*
   * parse a mixer unit
   */

  static int parse_audio_mixer_unit(struct mixer_build *state, int unitid, void *raw_desc)

  {

  	struct uac_mixer_unit_descriptor *desc = raw_desc;

  	struct usb_audio_term iterm;

  	int input_pins, num_ins, num_outs;
  	int pin, ich, err;

  	if (desc->bLength < 11 || ! (input_pins = desc->bNrInPins) || ! (num_outs = uac_mixer_unit_bNrChannels(desc))) {

  		snd_printk(KERN_ERR "invalid MIXER UNIT descriptor %d
  ", unitid);
  		return -EINVAL;
  	}
  	/* no bmControls field (e.g. Maya44) -> ignore */

  	if (desc->bLength <= 10 + input_pins) {

  		snd_printdd(KERN_INFO "MU %d has no bmControls field
  ", unitid);
  		return 0;
  	}
  
  	num_ins = 0;
  	ich = 0;
  	for (pin = 0; pin < input_pins; pin++) {

  		err = parse_audio_unit(state, desc->baSourceID[pin]);

  		if (err < 0)
  			return err;

  		err = check_input_term(state, desc->baSourceID[pin], &iterm);

  		if (err < 0)
  			return err;
  		num_ins += iterm.channels;
  		for (; ich < num_ins; ++ich) {
  			int och, ich_has_controls = 0;
  
  			for (och = 0; och < num_outs; ++och) {

  				if (check_matrix_bitmap(uac_mixer_unit_bmControls(desc, state->mixer->protocol),

  							ich, och, num_outs)) {
  					ich_has_controls = 1;
  					break;
  				}
  			}
  			if (ich_has_controls)
  				build_mixer_unit_ctl(state, desc, pin, ich,
  						     unitid, &iterm);
  		}
  	}
  	return 0;
  }
  
  
  /*
   * Processing Unit / Extension Unit
   */
  
  /* get callback for processing/extension unit */

  static int mixer_ctl_procunit_get(struct snd_kcontrol *kcontrol, struct snd_ctl_elem_value *ucontrol)

  {

  	struct usb_mixer_elem_info *cval = kcontrol->private_data;

  	int err, val;
  
  	err = get_cur_ctl_value(cval, cval->control << 8, &val);

  	if (err < 0 && cval->mixer->ignore_ctl_error) {

  		ucontrol->value.integer.value[0] = cval->min;
  		return 0;
  	}
  	if (err < 0)
  		return err;
  	val = get_relative_value(cval, val);
  	ucontrol->value.integer.value[0] = val;
  	return 0;
  }
  
  /* put callback for processing/extension unit */

  static int mixer_ctl_procunit_put(struct snd_kcontrol *kcontrol, struct snd_ctl_elem_value *ucontrol)

  {

  	struct usb_mixer_elem_info *cval = kcontrol->private_data;

  	int val, oval, err;
  
  	err = get_cur_ctl_value(cval, cval->control << 8, &oval);
  	if (err < 0) {

  		if (cval->mixer->ignore_ctl_error)

  			return 0;
  		return err;
  	}
  	val = ucontrol->value.integer.value[0];
  	val = get_abs_value(cval, val);
  	if (val != oval) {
  		set_cur_ctl_value(cval, cval->control << 8, val);
  		return 1;
  	}
  	return 0;
  }
  
  /* alsa control interface for processing/extension unit */

  static struct snd_kcontrol_new mixer_procunit_ctl = {

  	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
  	.name = "", /* will be filled later */
  	.info = mixer_ctl_feature_info,
  	.get = mixer_ctl_procunit_get,
  	.put = mixer_ctl_procunit_put,
  };
  
  
  /*
   * predefined data for processing units
   */
  struct procunit_value_info {
  	int control;
  	char *suffix;
  	int val_type;
  	int min_value;
  };
  
  struct procunit_info {
  	int type;
  	char *name;
  	struct procunit_value_info *values;
  };
  
  static struct procunit_value_info updown_proc_info[] = {

  	{ UAC_UD_ENABLE, "Switch", USB_MIXER_BOOLEAN },
  	{ UAC_UD_MODE_SELECT, "Mode Select", USB_MIXER_U8, 1 },

  	{ 0 }
  };
  static struct procunit_value_info prologic_proc_info[] = {

  	{ UAC_DP_ENABLE, "Switch", USB_MIXER_BOOLEAN },
  	{ UAC_DP_MODE_SELECT, "Mode Select", USB_MIXER_U8, 1 },

  	{ 0 }
  };
  static struct procunit_value_info threed_enh_proc_info[] = {

  	{ UAC_3D_ENABLE, "Switch", USB_MIXER_BOOLEAN },
  	{ UAC_3D_SPACE, "Spaciousness", USB_MIXER_U8 },

  	{ 0 }
  };
  static struct procunit_value_info reverb_proc_info[] = {

  	{ UAC_REVERB_ENABLE, "Switch", USB_MIXER_BOOLEAN },
  	{ UAC_REVERB_LEVEL, "Level", USB_MIXER_U8 },
  	{ UAC_REVERB_TIME, "Time", USB_MIXER_U16 },
  	{ UAC_REVERB_FEEDBACK, "Feedback", USB_MIXER_U8 },

  	{ 0 }
  };
  static struct procunit_value_info chorus_proc_info[] = {

  	{ UAC_CHORUS_ENABLE, "Switch", USB_MIXER_BOOLEAN },
  	{ UAC_CHORUS_LEVEL, "Level", USB_MIXER_U8 },
  	{ UAC_CHORUS_RATE, "Rate", USB_MIXER_U16 },
  	{ UAC_CHORUS_DEPTH, "Depth", USB_MIXER_U16 },

  	{ 0 }
  };
  static struct procunit_value_info dcr_proc_info[] = {

  	{ UAC_DCR_ENABLE, "Switch", USB_MIXER_BOOLEAN },
  	{ UAC_DCR_RATE, "Ratio", USB_MIXER_U16 },
  	{ UAC_DCR_MAXAMPL, "Max Amp", USB_MIXER_S16 },
  	{ UAC_DCR_THRESHOLD, "Threshold", USB_MIXER_S16 },
  	{ UAC_DCR_ATTACK_TIME, "Attack Time", USB_MIXER_U16 },
  	{ UAC_DCR_RELEASE_TIME, "Release Time", USB_MIXER_U16 },

  	{ 0 }
  };
  
  static struct procunit_info procunits[] = {

  	{ UAC_PROCESS_UP_DOWNMIX, "Up Down", updown_proc_info },
  	{ UAC_PROCESS_DOLBY_PROLOGIC, "Dolby Prologic", prologic_proc_info },
  	{ UAC_PROCESS_STEREO_EXTENDER, "3D Stereo Extender", threed_enh_proc_info },
  	{ UAC_PROCESS_REVERB, "Reverb", reverb_proc_info },
  	{ UAC_PROCESS_CHORUS, "Chorus", chorus_proc_info },
  	{ UAC_PROCESS_DYN_RANGE_COMP, "DCR", dcr_proc_info },

  	{ 0 },
  };

  /*
   * predefined data for extension units
   */
  static struct procunit_value_info clock_rate_xu_info[] = {

  	{ USB_XU_CLOCK_RATE_SELECTOR, "Selector", USB_MIXER_U8, 0 },
  	{ 0 }

  };
  static struct procunit_value_info clock_source_xu_info[] = {
  	{ USB_XU_CLOCK_SOURCE_SELECTOR, "External", USB_MIXER_BOOLEAN },
  	{ 0 }
  };
  static struct procunit_value_info spdif_format_xu_info[] = {
  	{ USB_XU_DIGITAL_FORMAT_SELECTOR, "SPDIF/AC3", USB_MIXER_BOOLEAN },
  	{ 0 }
  };
  static struct procunit_value_info soft_limit_xu_info[] = {
  	{ USB_XU_SOFT_LIMIT_SELECTOR, " ", USB_MIXER_BOOLEAN },
  	{ 0 }
  };
  static struct procunit_info extunits[] = {
  	{ USB_XU_CLOCK_RATE, "Clock rate", clock_rate_xu_info },
  	{ USB_XU_CLOCK_SOURCE, "DigitalIn CLK source", clock_source_xu_info },
  	{ USB_XU_DIGITAL_IO_STATUS, "DigitalOut format:", spdif_format_xu_info },
  	{ USB_XU_DEVICE_OPTIONS, "AnalogueIn Soft Limit", soft_limit_xu_info },
  	{ 0 }
  };

  /*
   * build a processing/extension unit
   */

  static int build_audio_procunit(struct mixer_build *state, int unitid, void *raw_desc, struct procunit_info *list, char *name)

  {

  	struct uac_processing_unit_descriptor *desc = raw_desc;
  	int num_ins = desc->bNrInPins;

  	struct usb_mixer_elem_info *cval;
  	struct snd_kcontrol *kctl;

  	int i, err, nameid, type, len;
  	struct procunit_info *info;
  	struct procunit_value_info *valinfo;

  	const struct usbmix_name_map *map;

  	static struct procunit_value_info default_value_info[] = {
  		{ 0x01, "Switch", USB_MIXER_BOOLEAN },
  		{ 0 }
  	};
  	static struct procunit_info default_info = {
  		0, NULL, default_value_info
  	};

  	if (desc->bLength < 13 || desc->bLength < 13 + num_ins ||
  	    desc->bLength < num_ins + uac_processing_unit_bControlSize(desc, state->mixer->protocol)) {

  		snd_printk(KERN_ERR "invalid %s descriptor (id %d)
  ", name, unitid);
  		return -EINVAL;
  	}
  
  	for (i = 0; i < num_ins; i++) {

  		if ((err = parse_audio_unit(state, desc->baSourceID[i])) < 0)

  			return err;
  	}

  	type = le16_to_cpu(desc->wProcessType);

  	for (info = list; info && info->type; info++)
  		if (info->type == type)
  			break;
  	if (! info || ! info->type)
  		info = &default_info;
  
  	for (valinfo = info->values; valinfo->control; valinfo++) {

  		__u8 *controls = uac_processing_unit_bmControls(desc, state->mixer->protocol);

  
  		if (! (controls[valinfo->control / 8] & (1 << ((valinfo->control % 8) - 1))))

  			continue;

  		map = find_map(state, unitid, valinfo->control);
  		if (check_ignored_ctl(map))

  			continue;

  		cval = kzalloc(sizeof(*cval), GFP_KERNEL);

  		if (! cval) {
  			snd_printk(KERN_ERR "cannot malloc kcontrol
  ");
  			return -ENOMEM;
  		}

  		cval->mixer = state->mixer;

  		cval->id = unitid;
  		cval->control = valinfo->control;
  		cval->val_type = valinfo->val_type;
  		cval->channels = 1;
  
  		/* get min/max values */

  		if (type == UAC_PROCESS_UP_DOWNMIX && cval->control == UAC_UD_MODE_SELECT) {

  			__u8 *control_spec = uac_processing_unit_specific(desc, state->mixer->protocol);

  			/* FIXME: hard-coded */
  			cval->min = 1;

  			cval->max = control_spec[0];

  			cval->res = 1;
  			cval->initialized = 1;

  		} else {
  			if (type == USB_XU_CLOCK_RATE) {

  				/* E-Mu USB 0404/0202/TrackerPre/0204

  				 * samplerate control quirk
  				 */
  				cval->min = 0;
  				cval->max = 5;
  				cval->res = 1;
  				cval->initialized = 1;
  			} else
  				get_min_max(cval, valinfo->min_value);
  		}

  
  		kctl = snd_ctl_new1(&mixer_procunit_ctl, cval);
  		if (! kctl) {
  			snd_printk(KERN_ERR "cannot malloc kcontrol
  ");
  			kfree(cval);
  			return -ENOMEM;
  		}
  		kctl->private_free = usb_mixer_elem_free;

  		if (check_mapped_name(map, kctl->id.name,
  						sizeof(kctl->id.name)))
  			/* nothing */ ;

  		else if (info->name)
  			strlcpy(kctl->id.name, info->name, sizeof(kctl->id.name));
  		else {

  			nameid = uac_processing_unit_iProcessing(desc, state->mixer->protocol);

  			len = 0;
  			if (nameid)
  				len = snd_usb_copy_string_desc(state, nameid, kctl->id.name, sizeof(kctl->id.name));
  			if (! len)
  				strlcpy(kctl->id.name, name, sizeof(kctl->id.name));
  		}

  		append_ctl_name(kctl, " ");
  		append_ctl_name(kctl, valinfo->suffix);

  
  		snd_printdd(KERN_INFO "[%d] PU [%s] ch = %d, val = %d/%d
  ",
  			    cval->id, kctl->id.name, cval->channels, cval->min, cval->max);

  		if ((err = snd_usb_mixer_add_control(state->mixer, kctl)) < 0)

  			return err;
  	}
  	return 0;
  }

  static int parse_audio_processing_unit(struct mixer_build *state, int unitid, void *raw_desc)

  {

  	return build_audio_procunit(state, unitid, raw_desc, procunits, "Processing Unit");

  }

  static int parse_audio_extension_unit(struct mixer_build *state, int unitid, void *raw_desc)

  {

  	/* Note that we parse extension units with processing unit descriptors.
  	 * That's ok as the layout is the same */
  	return build_audio_procunit(state, unitid, raw_desc, extunits, "Extension Unit");

  }
  
  
  /*
   * Selector Unit
   */
  
  /* info callback for selector unit
   * use an enumerator type for routing
   */

  static int mixer_ctl_selector_info(struct snd_kcontrol *kcontrol, struct snd_ctl_elem_info *uinfo)

  {

  	struct usb_mixer_elem_info *cval = kcontrol->private_data;

  	const char **itemlist = (const char **)kcontrol->private_value;

  	if (snd_BUG_ON(!itemlist))
  		return -EINVAL;

  	return snd_ctl_enum_info(uinfo, 1, cval->max, itemlist);

  }
  
  /* get callback for selector unit */

  static int mixer_ctl_selector_get(struct snd_kcontrol *kcontrol, struct snd_ctl_elem_value *ucontrol)

  {

  	struct usb_mixer_elem_info *cval = kcontrol->private_data;

  	int val, err;

  	err = get_cur_ctl_value(cval, cval->control << 8, &val);

  	if (err < 0) {

  		if (cval->mixer->ignore_ctl_error) {

  			ucontrol->value.enumerated.item[0] = 0;
  			return 0;
  		}
  		return err;
  	}
  	val = get_relative_value(cval, val);
  	ucontrol->value.enumerated.item[0] = val;
  	return 0;
  }
  
  /* put callback for selector unit */

  static int mixer_ctl_selector_put(struct snd_kcontrol *kcontrol, struct snd_ctl_elem_value *ucontrol)

  {

  	struct usb_mixer_elem_info *cval = kcontrol->private_data;

  	int val, oval, err;

  	err = get_cur_ctl_value(cval, cval->control << 8, &oval);

  	if (err < 0) {

  		if (cval->mixer->ignore_ctl_error)

  			return 0;
  		return err;
  	}
  	val = ucontrol->value.enumerated.item[0];
  	val = get_abs_value(cval, val);
  	if (val != oval) {

  		set_cur_ctl_value(cval, cval->control << 8, val);

  		return 1;
  	}
  	return 0;
  }
  
  /* alsa control interface for selector unit */

  static struct snd_kcontrol_new mixer_selectunit_ctl = {

  	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
  	.name = "", /* will be filled later */
  	.info = mixer_ctl_selector_info,
  	.get = mixer_ctl_selector_get,
  	.put = mixer_ctl_selector_put,
  };
  
  
  /* private free callback.
   * free both private_data and private_value
   */

  static void usb_mixer_selector_elem_free(struct snd_kcontrol *kctl)

  {
  	int i, num_ins = 0;
  
  	if (kctl->private_data) {

  		struct usb_mixer_elem_info *cval = kctl->private_data;

  		num_ins = cval->max;
  		kfree(cval);
  		kctl->private_data = NULL;
  	}
  	if (kctl->private_value) {
  		char **itemlist = (char **)kctl->private_value;
  		for (i = 0; i < num_ins; i++)
  			kfree(itemlist[i]);
  		kfree(itemlist);
  		kctl->private_value = 0;
  	}
  }
  
  /*
   * parse a selector unit
   */

  static int parse_audio_selector_unit(struct mixer_build *state, int unitid, void *raw_desc)

  {

  	struct uac_selector_unit_descriptor *desc = raw_desc;

  	unsigned int i, nameid, len;
  	int err;

  	struct usb_mixer_elem_info *cval;
  	struct snd_kcontrol *kctl;

  	const struct usbmix_name_map *map;

  	char **namelist;

  	if (!desc->bNrInPins || desc->bLength < 5 + desc->bNrInPins) {

  		snd_printk(KERN_ERR "invalid SELECTOR UNIT descriptor %d
  ", unitid);
  		return -EINVAL;
  	}

  	for (i = 0; i < desc->bNrInPins; i++) {
  		if ((err = parse_audio_unit(state, desc->baSourceID[i])) < 0)

  			return err;
  	}

  	if (desc->bNrInPins == 1) /* only one ? nonsense! */

  		return 0;

  	map = find_map(state, unitid, 0);
  	if (check_ignored_ctl(map))

  		return 0;

  	cval = kzalloc(sizeof(*cval), GFP_KERNEL);

  	if (! cval) {
  		snd_printk(KERN_ERR "cannot malloc kcontrol
  ");
  		return -ENOMEM;
  	}

  	cval->mixer = state->mixer;

  	cval->id = unitid;
  	cval->val_type = USB_MIXER_U8;
  	cval->channels = 1;
  	cval->min = 1;

  	cval->max = desc->bNrInPins;

  	cval->res = 1;
  	cval->initialized = 1;

  	if (desc->bDescriptorSubtype == UAC2_CLOCK_SELECTOR)
  		cval->control = UAC2_CX_CLOCK_SELECTOR;
  	else
  		cval->control = 0;

  	namelist = kmalloc(sizeof(char *) * desc->bNrInPins, GFP_KERNEL);

  	if (! namelist) {
  		snd_printk(KERN_ERR "cannot malloc
  ");
  		kfree(cval);
  		return -ENOMEM;
  	}
  #define MAX_ITEM_NAME_LEN	64

  	for (i = 0; i < desc->bNrInPins; i++) {

  		struct usb_audio_term iterm;

  		len = 0;
  		namelist[i] = kmalloc(MAX_ITEM_NAME_LEN, GFP_KERNEL);
  		if (! namelist[i]) {
  			snd_printk(KERN_ERR "cannot malloc
  ");

  			while (i--)

  				kfree(namelist[i]);
  			kfree(namelist);
  			kfree(cval);
  			return -ENOMEM;
  		}

  		len = check_mapped_selector_name(state, unitid, i, namelist[i],
  						 MAX_ITEM_NAME_LEN);

  		if (! len && check_input_term(state, desc->baSourceID[i], &iterm) >= 0)

  			len = get_term_name(state, &iterm, namelist[i], MAX_ITEM_NAME_LEN, 0);
  		if (! len)
  			sprintf(namelist[i], "Input %d", i);
  	}
  
  	kctl = snd_ctl_new1(&mixer_selectunit_ctl, cval);
  	if (! kctl) {
  		snd_printk(KERN_ERR "cannot malloc kcontrol
  ");

  		kfree(namelist);

  		kfree(cval);
  		return -ENOMEM;
  	}
  	kctl->private_value = (unsigned long)namelist;
  	kctl->private_free = usb_mixer_selector_elem_free;

  	nameid = uac_selector_unit_iSelector(desc);

  	len = check_mapped_name(map, kctl->id.name, sizeof(kctl->id.name));

  	if (len)
  		;
  	else if (nameid)
  		snd_usb_copy_string_desc(state, nameid, kctl->id.name, sizeof(kctl->id.name));
  	else {
  		len = get_term_name(state, &state->oterm,
  				    kctl->id.name, sizeof(kctl->id.name), 0);
  		if (! len)
  			strlcpy(kctl->id.name, "USB", sizeof(kctl->id.name));

  		if (desc->bDescriptorSubtype == UAC2_CLOCK_SELECTOR)
  			append_ctl_name(kctl, " Clock Source");
  		else if ((state->oterm.type & 0xff00) == 0x0100)

  			append_ctl_name(kctl, " Capture Source");

  		else

  			append_ctl_name(kctl, " Playback Source");

  	}
  
  	snd_printdd(KERN_INFO "[%d] SU [%s] items = %d
  ",

  		    cval->id, kctl->id.name, desc->bNrInPins);

  	if ((err = snd_usb_mixer_add_control(state->mixer, kctl)) < 0)

  		return err;
  
  	return 0;
  }
  
  
  /*
   * parse an audio unit recursively
   */

  static int parse_audio_unit(struct mixer_build *state, int unitid)

  {
  	unsigned char *p1;
  
  	if (test_and_set_bit(unitid, state->unitbitmap))
  		return 0; /* the unit already visited */
  
  	p1 = find_audio_control_unit(state, unitid);
  	if (!p1) {
  		snd_printk(KERN_ERR "usbaudio: unit %d not found!
  ", unitid);
  		return -EINVAL;
  	}
  
  	switch (p1[2]) {

  	case UAC_INPUT_TERMINAL:

  	case UAC2_CLOCK_SOURCE:

  		return 0; /* NOP */

  	case UAC_MIXER_UNIT:

  		return parse_audio_mixer_unit(state, unitid, p1);

  	case UAC_SELECTOR_UNIT:

  	case UAC2_CLOCK_SELECTOR:

  		return parse_audio_selector_unit(state, unitid, p1);

  	case UAC_FEATURE_UNIT:

  		return parse_audio_feature_unit(state, unitid, p1);

  	case UAC1_PROCESSING_UNIT:

  	/*   UAC2_EFFECT_UNIT has the same value */
  		if (state->mixer->protocol == UAC_VERSION_1)
  			return parse_audio_processing_unit(state, unitid, p1);
  		else
  			return 0; /* FIXME - effect units not implemented yet */

  	case UAC1_EXTENSION_UNIT:

  	/*   UAC2_PROCESSING_UNIT_V2 has the same value */
  		if (state->mixer->protocol == UAC_VERSION_1)
  			return parse_audio_extension_unit(state, unitid, p1);
  		else /* UAC_VERSION_2 */
  			return parse_audio_processing_unit(state, unitid, p1);

  	default:
  		snd_printk(KERN_ERR "usbaudio: unit %u: unexpected type 0x%02x
  ", unitid, p1[2]);
  		return -EINVAL;
  	}
  }

  static void snd_usb_mixer_free(struct usb_mixer_interface *mixer)
  {

  	kfree(mixer->id_elems);
  	if (mixer->urb) {
  		kfree(mixer->urb->transfer_buffer);
  		usb_free_urb(mixer->urb);
  	}

  	usb_free_urb(mixer->rc_urb);

  	kfree(mixer->rc_setup_packet);

  	kfree(mixer);
  }

  static int snd_usb_mixer_dev_free(struct snd_device *device)

  {
  	struct usb_mixer_interface *mixer = device->device_data;
  	snd_usb_mixer_free(mixer);
  	return 0;
  }

  /*
   * create mixer controls
   *

   * walk through all UAC_OUTPUT_TERMINAL descriptors to search for mixers

   */

  static int snd_usb_mixer_controls(struct usb_mixer_interface *mixer)

  {

  	struct mixer_build state;

  	int err;
  	const struct usbmix_ctl_map *map;

  	void *p;

  
  	memset(&state, 0, sizeof(state));

  	state.chip = mixer->chip;
  	state.mixer = mixer;

  	state.buffer = mixer->hostif->extra;
  	state.buflen = mixer->hostif->extralen;

  
  	/* check the mapping table */

  	for (map = usbmix_ctl_maps; map->id; map++) {
  		if (map->id == state.chip->usb_id) {

  			state.map = map->map;

  			state.selector_map = map->selector_map;

  			mixer->ignore_ctl_error = map->ignore_ctl_error;

  			break;
  		}
  	}

  	p = NULL;

  	while ((p = snd_usb_find_csint_desc(mixer->hostif->extra, mixer->hostif->extralen,
  					    p, UAC_OUTPUT_TERMINAL)) != NULL) {

  		if (mixer->protocol == UAC_VERSION_1) {

  			struct uac1_output_terminal_descriptor *desc = p;

  
  			if (desc->bLength < sizeof(*desc))
  				continue; /* invalid descriptor? */
  			set_bit(desc->bTerminalID, state.unitbitmap);  /* mark terminal ID as visited */
  			state.oterm.id = desc->bTerminalID;
  			state.oterm.type = le16_to_cpu(desc->wTerminalType);
  			state.oterm.name = desc->iTerminal;
  			err = parse_audio_unit(&state, desc->bSourceID);
  			if (err < 0)
  				return err;
  		} else { /* UAC_VERSION_2 */
  			struct uac2_output_terminal_descriptor *desc = p;
  
  			if (desc->bLength < sizeof(*desc))
  				continue; /* invalid descriptor? */
  			set_bit(desc->bTerminalID, state.unitbitmap);  /* mark terminal ID as visited */
  			state.oterm.id = desc->bTerminalID;
  			state.oterm.type = le16_to_cpu(desc->wTerminalType);
  			state.oterm.name = desc->iTerminal;
  			err = parse_audio_unit(&state, desc->bSourceID);
  			if (err < 0)
  				return err;

  
  			/* for UAC2, use the same approach to also add the clock selectors */
  			err = parse_audio_unit(&state, desc->bCSourceID);
  			if (err < 0)
  				return err;

  		}

  	}

  	return 0;
  }

  void snd_usb_mixer_notify_id(struct usb_mixer_interface *mixer, int unitid)

  {

  	struct usb_mixer_elem_info *info;

  
  	for (info = mixer->id_elems[unitid]; info; info = info->next_id_elem)
  		snd_ctl_notify(mixer->chip->card, SNDRV_CTL_EVENT_MASK_VALUE,
  			       info->elem_id);
  }

  static void snd_usb_mixer_dump_cval(struct snd_info_buffer *buffer,
  				    int unitid,
  				    struct usb_mixer_elem_info *cval)
  {
  	static char *val_types[] = {"BOOLEAN", "INV_BOOLEAN",
  				    "S8", "U8", "S16", "U16"};
  	snd_iprintf(buffer, "  Unit: %i
  ", unitid);
  	if (cval->elem_id)
  		snd_iprintf(buffer, "    Control: name=\"%s\", index=%i
  ",
  				cval->elem_id->name, cval->elem_id->index);
  	snd_iprintf(buffer, "    Info: id=%i, control=%i, cmask=0x%x, "
  			    "channels=%i, type=\"%s\"
  ", cval->id,
  			    cval->control, cval->cmask, cval->channels,
  			    val_types[cval->val_type]);
  	snd_iprintf(buffer, "    Volume: min=%i, max=%i, dBmin=%i, dBmax=%i
  ",
  			    cval->min, cval->max, cval->dBmin, cval->dBmax);
  }
  
  static void snd_usb_mixer_proc_read(struct snd_info_entry *entry,
  				    struct snd_info_buffer *buffer)
  {
  	struct snd_usb_audio *chip = entry->private_data;
  	struct usb_mixer_interface *mixer;
  	struct usb_mixer_elem_info *cval;
  	int unitid;
  
  	list_for_each_entry(mixer, &chip->mixer_list, list) {
  		snd_iprintf(buffer,

  			"USB Mixer: usb_id=0x%08x, ctrlif=%i, ctlerr=%i
  ",

  				chip->usb_id, snd_usb_ctrl_intf(chip),

  				mixer->ignore_ctl_error);

  		snd_iprintf(buffer, "Card: %s
  ", chip->card->longname);
  		for (unitid = 0; unitid < MAX_ID_ELEMS; unitid++) {
  			for (cval = mixer->id_elems[unitid]; cval;
  						cval = cval->next_id_elem)
  				snd_usb_mixer_dump_cval(buffer, unitid, cval);
  		}
  	}
  }

  static void snd_usb_mixer_interrupt_v2(struct usb_mixer_interface *mixer,
  				       int attribute, int value, int index)
  {
  	struct usb_mixer_elem_info *info;
  	__u8 unitid = (index >> 8) & 0xff;
  	__u8 control = (value >> 8) & 0xff;
  	__u8 channel = value & 0xff;
  
  	if (channel >= MAX_CHANNELS) {
  		snd_printk(KERN_DEBUG "%s(): bogus channel number %d
  ",
  				__func__, channel);
  		return;
  	}
  
  	for (info = mixer->id_elems[unitid]; info; info = info->next_id_elem) {
  		if (info->control != control)
  			continue;
  
  		switch (attribute) {
  		case UAC2_CS_CUR:
  			/* invalidate cache, so the value is read from the device */
  			if (channel)
  				info->cached &= ~(1 << channel);
  			else /* master channel */
  				info->cached = 0;
  
  			snd_ctl_notify(mixer->chip->card, SNDRV_CTL_EVENT_MASK_VALUE,
  					info->elem_id);
  			break;
  
  		case UAC2_CS_RANGE:
  			/* TODO */
  			break;
  
  		case UAC2_CS_MEM:
  			/* TODO */
  			break;
  
  		default:
  			snd_printk(KERN_DEBUG "unknown attribute %d in interrupt
  ",
  						attribute);
  			break;
  		} /* switch */
  	}
  }
  
  static void snd_usb_mixer_interrupt(struct urb *urb)

  {
  	struct usb_mixer_interface *mixer = urb->context;

  	int len = urb->actual_length;

  	int ustatus = urb->status;