/*
 *   (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
 *
 */

#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"

#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;
};

enum {
        USB_MIXER_BOOLEAN,
        USB_MIXER_INV_BOOLEAN,
        USB_MIXER_S8,
        USB_MIXER_U8,
        USB_MIXER_S16,
        USB_MIXER_U16,
};


/*E-mu 0202(0404) 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;
        }
}

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

        while (timeout-- > 0) {
                if (snd_usb_ctl_msg(cval->mixer->chip->dev,
                                    usb_rcvctrlpipe(cval->mixer->chip->dev, 0),
                                    request,
                                    USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
                                    validx, cval->mixer->ctrlif | (cval->id << 8),
                                    buf, val_len, 100) >= val_len) {
                        *value_ret = convert_signed_value(cval, snd_usb_combine_bytes(buf, val_len));
                        return 0;
                }
        }
        snd_printdd(KERN_ERR "cannot get ctl value: req = %#x, wValue = %#x, wIndex = %#x, type = %d\n",
                    request, validx, cval->mixer->ctrlif | (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)
{
        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_ctl_msg(cval->mixer->chip->dev,
                              usb_rcvctrlpipe(cval->mixer->chip->dev, 0),
                              bRequest,
                              USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
                              validx, cval->mixer->ctrlif | (cval->id << 8),
                              buf, size, 1000);

        if (ret < 0) {
                snd_printk(KERN_ERR "cannot get ctl value: req = %#x, wValue = %#x, wIndex = %#x, type = %d\n",
                           request, validx, cval->mixer->ctrlif | (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\n",
                                   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)
{
        unsigned char buf[2];
        int val_len, 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\n");
                        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;
        while (timeout-- > 0)
                if (snd_usb_ctl_msg(cval->mixer->chip->dev,
                                    usb_sndctrlpipe(cval->mixer->chip->dev, 0),
                                    request,
                                    USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_OUT,
                                    validx, cval->mixer->ctrlif | (cval->id << 8),
                                    buf, val_len, 100) >= 0)
                        return 0;
        snd_printdd(KERN_ERR "cannot set ctl value: req = %#x, wValue = %#x, wIndex = %#x, type = %d, data = %#x/%#x\n",
                    request, validx, cval->mixer->ctrlif | (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\n",
                            __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.
 */

static int add_control_to_empty(struct mixer_build *state, struct snd_kcontrol *kctl)
{
        struct usb_mixer_elem_info *cval = kctl->private_data;
        int err;

        while (snd_ctl_find_id(state->chip->card, &kctl->id))
                kctl->id.index++;
        if ((err = snd_ctl_add(state->chip->card, kctl)) < 0) {
                snd_printd(KERN_ERR "cannot add control (err = %d)\n", err);
                return err;
        }
        cval->elem_id = &kctl->id;
        cval->next_id_elem = state->mixer->id_elems[cval->id];
        state->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 UAC_PROCESSING_UNIT_V1:
                        strcpy(name, "Process Unit"); return 12;
                case UAC_EXTENSION_UNIT_V1:
                        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 UAC_PROCESSING_UNIT_V1:
                case UAC_EXTENSION_UNIT_V1: {
                        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
 */

/*
 * retrieve the minimum and maximum values for the specified control
 */
static int get_min_max(struct usb_mixer_elem_info *cval, int default_min)
{
        /* 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)\n",
                                   cval->id, cval->mixer->ctrlif, 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;
        }

        /* 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;
}


/* 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(cval,  0);
                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,
};


/*
 * 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;

        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\n");
                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;
        }

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

        /* 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\n");
                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));

        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) {
                        kctl->tlv.c = mixer_vol_tlv;
                        kctl->vd[0].access |= 
                                SNDRV_CTL_ELEM_ACCESS_TLV_READ |
                                SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;
                        check_mapped_dB(map, cval);
                }
                break;

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

        /* volume control quirks */
        switch (state->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\n");
                        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\n");
                        cval->min = 6080;
                        cval->max = 8768;
                        cval->res = 192;
                }
                break;

        case USB_ID(0x046d, 0x0809):
        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\n");
                        cval->res = 384;
                }
                break;

        }

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



/*
 * parse a feature unit
 *
 * most of controlls 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;
                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\n", 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\n");
                /* 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 < 30/2; i++) {
                        /* From the USB Audio spec v2.0:
                           bmaControls() is a (ch+1)-element array of 4-byte bitmaps,
                           each containing a set of bit pairs. If a Control is present,
                           it must be Host readable. If a certain Control is not
                           present then the bit pair must be set to 0b00.
                           If a Control is present but read-only, the bit pair must be
                           set to 0b01. If a Control is also Host programmable, the bit
                           pair must be set to 0b11. The value 0b10 is not allowed. */
                        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\n");
                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\n",
                    cval->id, kctl->id.name, cval->channels, cval->min, cval->max);
        add_control_to_empty(state, 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\n", 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\n", 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)\n", 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\n");
                        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
                                 * 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\n");
                        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\n",
                            cval->id, kctl->id.name, cval->channels, cval->min, cval->max);
                if ((err = add_control_to_empty(state, 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;
        char **itemlist = (char **)kcontrol->private_value;

        if (snd_BUG_ON(!itemlist))
                return -EINVAL;
        uinfo->type = SNDRV_CTL_ELEM_TYPE_ENUMERATED;
        uinfo->count = 1;
        uinfo->value.enumerated.items = cval->max;
        if ((int)uinfo->value.enumerated.item >= cval->max)
                uinfo->value.enumerated.item = cval->max - 1;
        strcpy(uinfo->value.enumerated.name, itemlist[uinfo->value.enumerated.item]);
        return 0;
}

/* 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\n", 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\n");
                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\n");
                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\n");
                        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\n");
                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\n",
                    cval->id, kctl->id.name, desc->bNrInPins);
        if ((err = add_control_to_empty(state, 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!\n", 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 UAC_PROCESSING_UNIT_V1:
        /*   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 UAC_EXTENSION_UNIT_V1:
        /*   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\n", 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;
        struct usb_host_interface *hostif;
        void *p;

        hostif = &usb_ifnum_to_if(mixer->chip->dev, mixer->ctrlif)->altsetting[0];
        memset(&state, 0, sizeof(state));
        state.chip = mixer->chip;
        state.mixer = mixer;
        state.buffer = hostif->extra;
        state.buflen = 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(hostif->extra, hostif->extralen, p, UAC_OUTPUT_TERMINAL)) != NULL) {
                if (mixer->protocol == UAC_VERSION_1) {
                        struct uac_output_terminal_descriptor_v1 *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\n", unitid);
        if (cval->elem_id)
                snd_iprintf(buffer, "    Control: name=\"%s\", index=%i\n",
                                cval->elem_id->name, cval->elem_id->index);
        snd_iprintf(buffer, "    Info: id=%i, control=%i, cmask=0x%x, "
                            "channels=%i, type=\"%s\"\n", 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\n",
                            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\n",
                                chip->usb_id, mixer->ctrlif,

                                mixer->ignore_ctl_error);
                snd_iprintf(buffer, "Card: %s\n", 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\n",
                                __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\n",
                                                attribute);
                        break;
                } /* switch */
        }
}

static void snd_usb_mixer_interrupt(struct urb *urb)
{
        struct usb_mixer_interface *mixer = urb->context;
        int len = urb->actual_length;

        if (urb->status != 0)
                goto requeue;

        if (mixer->protocol == UAC_VERSION_1) {
                struct uac1_status_word *status;

                for (status = urb->transfer_buffer;
                     len >= sizeof(*status);
                     len -= sizeof(*status), status++) {
                        snd_printd(KERN_DEBUG "status interrupt: %02x %02x\n",
                                                status->bStatusType,
                                                status->bOriginator);

                        /* ignore any notifications not from the control interface */
                        if ((status->bStatusType & UAC1_STATUS_TYPE_ORIG_MASK) !=
                                UAC1_STATUS_TYPE_ORIG_AUDIO_CONTROL_IF)
                                continue;

                        if (status->bStatusType & UAC1_STATUS_TYPE_MEM_CHANGED)
                                snd_usb_mixer_rc_memory_change(mixer, status->bOriginator);
                        else
                                snd_usb_mixer_notify_id(mixer, status->bOriginator);
                }
        } else { /* UAC_VERSION_2 */
                struct uac2_interrupt_data_msg *msg;

                for (msg = urb->transfer_buffer;
                     len >= sizeof(*msg);
                     len -= sizeof(*msg), msg++) {
                        /* drop vendor specific and endpoint requests */
                        if ((msg->bInfo & UAC2_INTERRUPT_DATA_MSG_VENDOR) ||
                            (msg->bInfo & UAC2_INTERRUPT_DATA_MSG_EP))
                                continue;

                        snd_usb_mixer_interrupt_v2(mixer, msg->bAttribute,
                                                   le16_to_cpu(msg->wValue),
                                                   le16_to_cpu(msg->wIndex));
                }
        }

requeue:
        if (urb->status != -ENOENT && urb->status != -ECONNRESET) {
                urb->dev = mixer->chip->dev;
                usb_submit_urb(urb, GFP_ATOMIC);
        }
}

/* create the handler for the optional status interrupt endpoint */
static int snd_usb_mixer_status_create(struct usb_mixer_interface *mixer)
{
        struct usb_host_interface *hostif;
        struct usb_endpoint_descriptor *ep;
        void *transfer_buffer;
        int buffer_length;
        unsigned int epnum;

        hostif = &usb_ifnum_to_if(mixer->chip->dev, mixer->ctrlif)->altsetting[0];
        /* we need one interrupt input endpoint */
        if (get_iface_desc(hostif)->bNumEndpoints < 1)
                return 0;
        ep = get_endpoint(hostif, 0);
        if (!usb_endpoint_dir_in(ep) || !usb_endpoint_xfer_int(ep))
                return 0;

        epnum = usb_endpoint_num(ep);
        buffer_length = le16_to_cpu(ep->wMaxPacketSize);
        transfer_buffer = kmalloc(buffer_length, GFP_KERNEL);
        if (!transfer_buffer)
                return -ENOMEM;
        mixer->urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!mixer->urb) {
                kfree(transfer_buffer);
                return -ENOMEM;
        }
        usb_fill_int_urb(mixer->urb, mixer->chip->dev,
                         usb_rcvintpipe(mixer->chip->dev, epnum),
                         transfer_buffer, buffer_length,
                         snd_usb_mixer_interrupt, mixer, ep->bInterval);
        usb_submit_urb(mixer->urb, GFP_KERNEL);
        return 0;
}

int snd_usb_create_mixer(struct snd_usb_audio *chip, int ctrlif,
                         int ignore_error)
{
        static struct snd_device_ops dev_ops = {
                .dev_free = snd_usb_mixer_dev_free
        };
        struct usb_mixer_interface *mixer;
        struct snd_info_entry *entry;
        struct usb_host_interface *host_iface;
        int err;

        strcpy(chip->card->mixername, "USB Mixer");

        mixer = kzalloc(sizeof(*mixer), GFP_KERNEL);
        if (!mixer)
                return -ENOMEM;
        mixer->chip = chip;
        mixer->ctrlif = ctrlif;
        mixer->ignore_ctl_error = ignore_error;
        mixer->id_elems = kcalloc(MAX_ID_ELEMS, sizeof(*mixer->id_elems),
                                  GFP_KERNEL);
        if (!mixer->id_elems) {
                kfree(mixer);
                return -ENOMEM;
        }

        host_iface = &usb_ifnum_to_if(chip->dev, ctrlif)->altsetting[0];
        mixer->protocol = get_iface_desc(host_iface)->bInterfaceProtocol;

        if ((err = snd_usb_mixer_controls(mixer)) < 0 ||
            (err = snd_usb_mixer_status_create(mixer)) < 0)
                goto _error;

        snd_usb_mixer_apply_create_quirk(mixer);

        err = snd_device_new(chip->card, SNDRV_DEV_LOWLEVEL, mixer, &dev_ops);
        if (err < 0)
                goto _error;

        if (list_empty(&chip->mixer_list) &&
            !snd_card_proc_new(chip->card, "usbmixer", &entry))
                snd_info_set_text_ops(entry, chip, snd_usb_mixer_proc_read);

        list_add(&mixer->list, &chip->mixer_list);
        return 0;

_error:
        snd_usb_mixer_free(mixer);
        return err;
}

void snd_usb_mixer_disconnect(struct list_head *p)
{
        struct usb_mixer_interface *mixer;

        mixer = list_entry(p, struct usb_mixer_interface, list);
        usb_kill_urb(mixer->urb);
        usb_kill_urb(mixer->rc_urb);
}