// SPDX-License-Identifier: GPL-2.0+
/*
 * f_uac2.c -- USB Audio Class 2.0 Function
 *
 * Copyright (C) 2011
 *    Yadwinder Singh (yadi.brar01@gmail.com)
 *    Jaswinder Singh (jaswinder.singh@linaro.org)
 *
 * Copyright (C) 2020
 *    Ruslan Bilovol (ruslan.bilovol@gmail.com)
 */

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

#include "u_audio.h"

#include "u_uac2.h"

/* UAC2 spec: 4.1 Audio Channel Cluster Descriptor */
#define UAC2_CHANNEL_MASK 0x07FFFFFF

/*
 * The driver implements a simple UAC_2 topology.
 * USB-OUT -> IT_1 -> FU -> OT_3 -> ALSA_Capture
 * ALSA_Playback -> IT_2 -> FU -> OT_4 -> USB-IN
 * Capture and Playback sampling rates are independently
 *  controlled by two clock sources :
 *    CLK_5 := c_srate, and CLK_6 := p_srate
 */
#define USB_OUT_CLK_ID  (out_clk_src_desc.bClockID)
#define USB_IN_CLK_ID   (in_clk_src_desc.bClockID)
#define USB_OUT_FU_ID   (out_feature_unit_desc->bUnitID)
#define USB_IN_FU_ID    (in_feature_unit_desc->bUnitID)

#define CONTROL_ABSENT  0
#define CONTROL_RDONLY  1
#define CONTROL_RDWR    3

#define CLK_FREQ_CTRL   0
#define CLK_VLD_CTRL    2
#define FU_MUTE_CTRL    0
#define FU_VOL_CTRL     2

#define COPY_CTRL       0
#define CONN_CTRL       2
#define OVRLD_CTRL      4
#define CLSTR_CTRL      6
#define UNFLW_CTRL      8
#define OVFLW_CTRL      10

#define EPIN_EN(_opts) ((_opts)->p_chmask != 0)
#define EPOUT_EN(_opts) ((_opts)->c_chmask != 0)
#define FUIN_EN(_opts) (EPIN_EN(_opts) \
                                && ((_opts)->p_mute_present \
                                || (_opts)->p_volume_present))
#define FUOUT_EN(_opts) (EPOUT_EN(_opts) \
                                && ((_opts)->c_mute_present \
                                || (_opts)->c_volume_present))
#define EPOUT_FBACK_IN_EN(_opts) ((_opts)->c_sync == USB_ENDPOINT_SYNC_ASYNC)

struct f_uac2 {
        struct g_audio g_audio;
        u8 ac_intf, as_in_intf, as_out_intf;
        u8 ac_alt, as_in_alt, as_out_alt;       /* needed for get_alt() */

        struct usb_ctrlrequest setup_cr;        /* will be used in data stage */

        /* Interrupt IN endpoint of AC interface */
        struct usb_ep   *int_ep;
        atomic_t        int_count;
        /* transient state, only valid during handling of a single control request */
        int clock_id;
};

static inline struct f_uac2 *func_to_uac2(struct usb_function *f)
{
        return container_of(f, struct f_uac2, g_audio.func);
}

static inline
struct f_uac2_opts *g_audio_to_uac2_opts(struct g_audio *agdev)
{
        return container_of(agdev->func.fi, struct f_uac2_opts, func_inst);
}

static int afunc_notify(struct g_audio *agdev, int unit_id, int cs);

/* --------- USB Function Interface ------------- */

enum {
        STR_ASSOC,
        STR_IF_CTRL,
        STR_CLKSRC_IN,
        STR_CLKSRC_OUT,
        STR_USB_IT,
        STR_USB_IT_CH,
        STR_IO_IT,
        STR_IO_IT_CH,
        STR_USB_OT,
        STR_IO_OT,
        STR_FU_IN,
        STR_FU_OUT,
        STR_AS_OUT_ALT0,
        STR_AS_OUT_ALT1,
        STR_AS_IN_ALT0,
        STR_AS_IN_ALT1,
        NUM_STR_DESCRIPTORS,
};

static struct usb_string strings_fn[NUM_STR_DESCRIPTORS + 1] = {};

static const char *const speed_names[] = {
        [USB_SPEED_UNKNOWN] = "UNKNOWN",
        [USB_SPEED_LOW] = "LS",
        [USB_SPEED_FULL] = "FS",
        [USB_SPEED_HIGH] = "HS",
        [USB_SPEED_WIRELESS] = "W",
        [USB_SPEED_SUPER] = "SS",
        [USB_SPEED_SUPER_PLUS] = "SS+",
};

static struct usb_gadget_strings str_fn = {
        .language = 0x0409,     /* en-us */
        .strings = strings_fn,
};

static struct usb_gadget_strings *fn_strings[] = {
        &str_fn,
        NULL,
};

static struct usb_interface_assoc_descriptor iad_desc = {
        .bLength = sizeof iad_desc,
        .bDescriptorType = USB_DT_INTERFACE_ASSOCIATION,

        .bFirstInterface = 0,
        .bInterfaceCount = 3,
        .bFunctionClass = USB_CLASS_AUDIO,
        .bFunctionSubClass = UAC2_FUNCTION_SUBCLASS_UNDEFINED,
        .bFunctionProtocol = UAC_VERSION_2,
};

/* Audio Control Interface */
static struct usb_interface_descriptor std_ac_if_desc = {
        .bLength = sizeof std_ac_if_desc,
        .bDescriptorType = USB_DT_INTERFACE,

        .bAlternateSetting = 0,
        /* .bNumEndpoints = DYNAMIC */
        .bInterfaceClass = USB_CLASS_AUDIO,
        .bInterfaceSubClass = USB_SUBCLASS_AUDIOCONTROL,
        .bInterfaceProtocol = UAC_VERSION_2,
};

/* Clock source for IN traffic */
static struct uac_clock_source_descriptor in_clk_src_desc = {
        .bLength = sizeof in_clk_src_desc,
        .bDescriptorType = USB_DT_CS_INTERFACE,

        .bDescriptorSubtype = UAC2_CLOCK_SOURCE,
        /* .bClockID = DYNAMIC */
        .bmAttributes = UAC_CLOCK_SOURCE_TYPE_INT_FIXED,
        .bmControls = (CONTROL_RDWR << CLK_FREQ_CTRL),
        .bAssocTerminal = 0,
};

/* Clock source for OUT traffic */
static struct uac_clock_source_descriptor out_clk_src_desc = {
        .bLength = sizeof out_clk_src_desc,
        .bDescriptorType = USB_DT_CS_INTERFACE,

        .bDescriptorSubtype = UAC2_CLOCK_SOURCE,
        /* .bClockID = DYNAMIC */
        .bmAttributes = UAC_CLOCK_SOURCE_TYPE_INT_FIXED,
        .bmControls = (CONTROL_RDWR << CLK_FREQ_CTRL),
        .bAssocTerminal = 0,
};

/* Input Terminal for USB_OUT */
static struct uac2_input_terminal_descriptor usb_out_it_desc = {
        .bLength = sizeof usb_out_it_desc,
        .bDescriptorType = USB_DT_CS_INTERFACE,

        .bDescriptorSubtype = UAC_INPUT_TERMINAL,
        /* .bTerminalID = DYNAMIC */
        .wTerminalType = cpu_to_le16(UAC_TERMINAL_STREAMING),
        .bAssocTerminal = 0,
        /* .bCSourceID = DYNAMIC */
        .iChannelNames = 0,
        .bmControls = cpu_to_le16(CONTROL_RDWR << COPY_CTRL),
};

/* Input Terminal for I/O-In */
static struct uac2_input_terminal_descriptor io_in_it_desc = {
        .bLength = sizeof io_in_it_desc,
        .bDescriptorType = USB_DT_CS_INTERFACE,

        .bDescriptorSubtype = UAC_INPUT_TERMINAL,
        /* .bTerminalID = DYNAMIC */
        /* .wTerminalType = DYNAMIC */
        .bAssocTerminal = 0,
        /* .bCSourceID = DYNAMIC */
        .iChannelNames = 0,
        .bmControls = cpu_to_le16(CONTROL_RDWR << COPY_CTRL),
};

/* Ouput Terminal for USB_IN */
static struct uac2_output_terminal_descriptor usb_in_ot_desc = {
        .bLength = sizeof usb_in_ot_desc,
        .bDescriptorType = USB_DT_CS_INTERFACE,

        .bDescriptorSubtype = UAC_OUTPUT_TERMINAL,
        /* .bTerminalID = DYNAMIC */
        .wTerminalType = cpu_to_le16(UAC_TERMINAL_STREAMING),
        .bAssocTerminal = 0,
        /* .bSourceID = DYNAMIC */
        /* .bCSourceID = DYNAMIC */
        .bmControls = cpu_to_le16(CONTROL_RDWR << COPY_CTRL),
};

/* Ouput Terminal for I/O-Out */
static struct uac2_output_terminal_descriptor io_out_ot_desc = {
        .bLength = sizeof io_out_ot_desc,
        .bDescriptorType = USB_DT_CS_INTERFACE,

        .bDescriptorSubtype = UAC_OUTPUT_TERMINAL,
        /* .bTerminalID = DYNAMIC */
        /* .wTerminalType = DYNAMIC */
        .bAssocTerminal = 0,
        /* .bSourceID = DYNAMIC */
        /* .bCSourceID = DYNAMIC */
        .bmControls = cpu_to_le16(CONTROL_RDWR << COPY_CTRL),
};

static struct uac2_feature_unit_descriptor *in_feature_unit_desc;
static struct uac2_feature_unit_descriptor *out_feature_unit_desc;

static struct uac2_ac_header_descriptor ac_hdr_desc = {
        .bLength = sizeof ac_hdr_desc,
        .bDescriptorType = USB_DT_CS_INTERFACE,

        .bDescriptorSubtype = UAC_MS_HEADER,
        .bcdADC = cpu_to_le16(0x200),
        .bCategory = UAC2_FUNCTION_IO_BOX,
        /* .wTotalLength = DYNAMIC */
        .bmControls = 0,
};

/* AC IN Interrupt Endpoint */
static struct usb_endpoint_descriptor fs_ep_int_desc = {
        .bLength = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType = USB_DT_ENDPOINT,

        .bEndpointAddress = USB_DIR_IN,
        .bmAttributes = USB_ENDPOINT_XFER_INT,
        .wMaxPacketSize = cpu_to_le16(6),
        .bInterval = 1,
};

static struct usb_endpoint_descriptor hs_ep_int_desc = {
        .bLength = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType = USB_DT_ENDPOINT,

        .bmAttributes = USB_ENDPOINT_XFER_INT,
        .wMaxPacketSize = cpu_to_le16(6),
        .bInterval = 4,
};

static struct usb_endpoint_descriptor ss_ep_int_desc = {
        .bLength = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType = USB_DT_ENDPOINT,

        .bEndpointAddress = USB_DIR_IN,
        .bmAttributes = USB_ENDPOINT_XFER_INT,
        .wMaxPacketSize = cpu_to_le16(6),
        .bInterval = 4,
};

static struct usb_ss_ep_comp_descriptor ss_ep_int_desc_comp = {
        .bLength = sizeof(ss_ep_int_desc_comp),
        .bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
        .wBytesPerInterval = cpu_to_le16(6),
};

/* Audio Streaming OUT Interface - Alt0 */
static struct usb_interface_descriptor std_as_out_if0_desc = {
        .bLength = sizeof std_as_out_if0_desc,
        .bDescriptorType = USB_DT_INTERFACE,

        .bAlternateSetting = 0,
        .bNumEndpoints = 0,
        .bInterfaceClass = USB_CLASS_AUDIO,
        .bInterfaceSubClass = USB_SUBCLASS_AUDIOSTREAMING,
        .bInterfaceProtocol = UAC_VERSION_2,
};

/* Audio Streaming OUT Interface - Alt1 */
static struct usb_interface_descriptor std_as_out_if1_desc = {
        .bLength = sizeof std_as_out_if1_desc,
        .bDescriptorType = USB_DT_INTERFACE,

        .bAlternateSetting = 1,
        .bNumEndpoints = 1,
        .bInterfaceClass = USB_CLASS_AUDIO,
        .bInterfaceSubClass = USB_SUBCLASS_AUDIOSTREAMING,
        .bInterfaceProtocol = UAC_VERSION_2,
};

/* Audio Stream OUT Intface Desc */
static struct uac2_as_header_descriptor as_out_hdr_desc = {
        .bLength = sizeof as_out_hdr_desc,
        .bDescriptorType = USB_DT_CS_INTERFACE,

        .bDescriptorSubtype = UAC_AS_GENERAL,
        /* .bTerminalLink = DYNAMIC */
        .bmControls = 0,
        .bFormatType = UAC_FORMAT_TYPE_I,
        .bmFormats = cpu_to_le32(UAC_FORMAT_TYPE_I_PCM),
        .iChannelNames = 0,
};

/* Audio USB_OUT Format */
static struct uac2_format_type_i_descriptor as_out_fmt1_desc = {
        .bLength = sizeof as_out_fmt1_desc,
        .bDescriptorType = USB_DT_CS_INTERFACE,
        .bDescriptorSubtype = UAC_FORMAT_TYPE,
        .bFormatType = UAC_FORMAT_TYPE_I,
};

/* STD AS ISO OUT Endpoint */
static struct usb_endpoint_descriptor fs_epout_desc = {
        .bLength = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType = USB_DT_ENDPOINT,

        .bEndpointAddress = USB_DIR_OUT,
        /* .bmAttributes = DYNAMIC */
        /* .wMaxPacketSize = DYNAMIC */
        .bInterval = 1,
};

static struct usb_endpoint_descriptor hs_epout_desc = {
        .bLength = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType = USB_DT_ENDPOINT,

        /* .bmAttributes = DYNAMIC */
        /* .wMaxPacketSize = DYNAMIC */
        /* .bInterval = DYNAMIC */
};

static struct usb_endpoint_descriptor ss_epout_desc = {
        .bLength = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType = USB_DT_ENDPOINT,

        .bEndpointAddress = USB_DIR_OUT,
        /* .bmAttributes = DYNAMIC */
        /* .wMaxPacketSize = DYNAMIC */
        /* .bInterval = DYNAMIC */
};

static struct usb_ss_ep_comp_descriptor ss_epout_desc_comp = {
        .bLength                = sizeof(ss_epout_desc_comp),
        .bDescriptorType        = USB_DT_SS_ENDPOINT_COMP,
        .bMaxBurst              = 0,
        .bmAttributes           = 0,
        /* wBytesPerInterval = DYNAMIC */
};

/* CS AS ISO OUT Endpoint */
static struct uac2_iso_endpoint_descriptor as_iso_out_desc = {
        .bLength = sizeof as_iso_out_desc,
        .bDescriptorType = USB_DT_CS_ENDPOINT,

        .bDescriptorSubtype = UAC_EP_GENERAL,
        .bmAttributes = 0,
        .bmControls = 0,
        .bLockDelayUnits = 0,
        .wLockDelay = 0,
};

/* STD AS ISO IN Feedback Endpoint */
static struct usb_endpoint_descriptor fs_epin_fback_desc = {
        .bLength = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType = USB_DT_ENDPOINT,

        .bEndpointAddress = USB_DIR_IN,
        .bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_USAGE_FEEDBACK,
        .wMaxPacketSize = cpu_to_le16(3),
        .bInterval = 1,
};

static struct usb_endpoint_descriptor hs_epin_fback_desc = {
        .bLength = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType = USB_DT_ENDPOINT,

        .bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_USAGE_FEEDBACK,
        .wMaxPacketSize = cpu_to_le16(4),
        .bInterval = 4,
};

static struct usb_endpoint_descriptor ss_epin_fback_desc = {
        .bLength = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType = USB_DT_ENDPOINT,

        .bEndpointAddress = USB_DIR_IN,
        .bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_USAGE_FEEDBACK,
        .wMaxPacketSize = cpu_to_le16(4),
        .bInterval = 4,
};

static struct usb_ss_ep_comp_descriptor ss_epin_fback_desc_comp = {
        .bLength                = sizeof(ss_epin_fback_desc_comp),
        .bDescriptorType        = USB_DT_SS_ENDPOINT_COMP,
        .bMaxBurst              = 0,
        .bmAttributes           = 0,
        .wBytesPerInterval      = cpu_to_le16(4),
};


/* Audio Streaming IN Interface - Alt0 */
static struct usb_interface_descriptor std_as_in_if0_desc = {
        .bLength = sizeof std_as_in_if0_desc,
        .bDescriptorType = USB_DT_INTERFACE,

        .bAlternateSetting = 0,
        .bNumEndpoints = 0,
        .bInterfaceClass = USB_CLASS_AUDIO,
        .bInterfaceSubClass = USB_SUBCLASS_AUDIOSTREAMING,
        .bInterfaceProtocol = UAC_VERSION_2,
};

/* Audio Streaming IN Interface - Alt1 */
static struct usb_interface_descriptor std_as_in_if1_desc = {
        .bLength = sizeof std_as_in_if1_desc,
        .bDescriptorType = USB_DT_INTERFACE,

        .bAlternateSetting = 1,
        .bNumEndpoints = 1,
        .bInterfaceClass = USB_CLASS_AUDIO,
        .bInterfaceSubClass = USB_SUBCLASS_AUDIOSTREAMING,
        .bInterfaceProtocol = UAC_VERSION_2,
};

/* Audio Stream IN Intface Desc */
static struct uac2_as_header_descriptor as_in_hdr_desc = {
        .bLength = sizeof as_in_hdr_desc,
        .bDescriptorType = USB_DT_CS_INTERFACE,

        .bDescriptorSubtype = UAC_AS_GENERAL,
        /* .bTerminalLink = DYNAMIC */
        .bmControls = 0,
        .bFormatType = UAC_FORMAT_TYPE_I,
        .bmFormats = cpu_to_le32(UAC_FORMAT_TYPE_I_PCM),
        .iChannelNames = 0,
};

/* Audio USB_IN Format */
static struct uac2_format_type_i_descriptor as_in_fmt1_desc = {
        .bLength = sizeof as_in_fmt1_desc,
        .bDescriptorType = USB_DT_CS_INTERFACE,
        .bDescriptorSubtype = UAC_FORMAT_TYPE,
        .bFormatType = UAC_FORMAT_TYPE_I,
};

/* STD AS ISO IN Endpoint */
static struct usb_endpoint_descriptor fs_epin_desc = {
        .bLength = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType = USB_DT_ENDPOINT,

        .bEndpointAddress = USB_DIR_IN,
        .bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,
        /* .wMaxPacketSize = DYNAMIC */
        .bInterval = 1,
};

static struct usb_endpoint_descriptor hs_epin_desc = {
        .bLength = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType = USB_DT_ENDPOINT,

        .bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,
        /* .wMaxPacketSize = DYNAMIC */
        /* .bInterval = DYNAMIC */
};

static struct usb_endpoint_descriptor ss_epin_desc = {
        .bLength = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType = USB_DT_ENDPOINT,

        .bEndpointAddress = USB_DIR_IN,
        .bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,
        /* .wMaxPacketSize = DYNAMIC */
        /* .bInterval = DYNAMIC */
};

static struct usb_ss_ep_comp_descriptor ss_epin_desc_comp = {
        .bLength                = sizeof(ss_epin_desc_comp),
        .bDescriptorType        = USB_DT_SS_ENDPOINT_COMP,
        .bMaxBurst              = 0,
        .bmAttributes           = 0,
        /* wBytesPerInterval = DYNAMIC */
};

/* CS AS ISO IN Endpoint */
static struct uac2_iso_endpoint_descriptor as_iso_in_desc = {
        .bLength = sizeof as_iso_in_desc,
        .bDescriptorType = USB_DT_CS_ENDPOINT,

        .bDescriptorSubtype = UAC_EP_GENERAL,
        .bmAttributes = 0,
        .bmControls = 0,
        .bLockDelayUnits = 0,
        .wLockDelay = 0,
};

static struct usb_descriptor_header *fs_audio_desc[] = {
        (struct usb_descriptor_header *)&iad_desc,
        (struct usb_descriptor_header *)&std_ac_if_desc,

        (struct usb_descriptor_header *)&ac_hdr_desc,
        (struct usb_descriptor_header *)&in_clk_src_desc,
        (struct usb_descriptor_header *)&out_clk_src_desc,
        (struct usb_descriptor_header *)&usb_out_it_desc,
        (struct usb_descriptor_header *)&out_feature_unit_desc,
        (struct usb_descriptor_header *)&io_in_it_desc,
        (struct usb_descriptor_header *)&usb_in_ot_desc,
        (struct usb_descriptor_header *)&in_feature_unit_desc,
        (struct usb_descriptor_header *)&io_out_ot_desc,

        (struct usb_descriptor_header *)&fs_ep_int_desc,

        (struct usb_descriptor_header *)&std_as_out_if0_desc,
        (struct usb_descriptor_header *)&std_as_out_if1_desc,

        (struct usb_descriptor_header *)&as_out_hdr_desc,
        (struct usb_descriptor_header *)&as_out_fmt1_desc,
        (struct usb_descriptor_header *)&fs_epout_desc,
        (struct usb_descriptor_header *)&as_iso_out_desc,
        (struct usb_descriptor_header *)&fs_epin_fback_desc,

        (struct usb_descriptor_header *)&std_as_in_if0_desc,
        (struct usb_descriptor_header *)&std_as_in_if1_desc,

        (struct usb_descriptor_header *)&as_in_hdr_desc,
        (struct usb_descriptor_header *)&as_in_fmt1_desc,
        (struct usb_descriptor_header *)&fs_epin_desc,
        (struct usb_descriptor_header *)&as_iso_in_desc,
        NULL,
};

static struct usb_descriptor_header *hs_audio_desc[] = {
        (struct usb_descriptor_header *)&iad_desc,
        (struct usb_descriptor_header *)&std_ac_if_desc,

        (struct usb_descriptor_header *)&ac_hdr_desc,
        (struct usb_descriptor_header *)&in_clk_src_desc,
        (struct usb_descriptor_header *)&out_clk_src_desc,
        (struct usb_descriptor_header *)&usb_out_it_desc,
        (struct usb_descriptor_header *)&out_feature_unit_desc,
        (struct usb_descriptor_header *)&io_in_it_desc,
        (struct usb_descriptor_header *)&usb_in_ot_desc,
        (struct usb_descriptor_header *)&in_feature_unit_desc,
        (struct usb_descriptor_header *)&io_out_ot_desc,

        (struct usb_descriptor_header *)&hs_ep_int_desc,

        (struct usb_descriptor_header *)&std_as_out_if0_desc,
        (struct usb_descriptor_header *)&std_as_out_if1_desc,

        (struct usb_descriptor_header *)&as_out_hdr_desc,
        (struct usb_descriptor_header *)&as_out_fmt1_desc,
        (struct usb_descriptor_header *)&hs_epout_desc,
        (struct usb_descriptor_header *)&as_iso_out_desc,
        (struct usb_descriptor_header *)&hs_epin_fback_desc,

        (struct usb_descriptor_header *)&std_as_in_if0_desc,
        (struct usb_descriptor_header *)&std_as_in_if1_desc,

        (struct usb_descriptor_header *)&as_in_hdr_desc,
        (struct usb_descriptor_header *)&as_in_fmt1_desc,
        (struct usb_descriptor_header *)&hs_epin_desc,
        (struct usb_descriptor_header *)&as_iso_in_desc,
        NULL,
};

static struct usb_descriptor_header *ss_audio_desc[] = {
        (struct usb_descriptor_header *)&iad_desc,
        (struct usb_descriptor_header *)&std_ac_if_desc,

        (struct usb_descriptor_header *)&ac_hdr_desc,
        (struct usb_descriptor_header *)&in_clk_src_desc,
        (struct usb_descriptor_header *)&out_clk_src_desc,
        (struct usb_descriptor_header *)&usb_out_it_desc,
  (struct usb_descriptor_header *)&out_feature_unit_desc,
        (struct usb_descriptor_header *)&io_in_it_desc,
        (struct usb_descriptor_header *)&usb_in_ot_desc,
        (struct usb_descriptor_header *)&in_feature_unit_desc,
        (struct usb_descriptor_header *)&io_out_ot_desc,

        (struct usb_descriptor_header *)&ss_ep_int_desc,
        (struct usb_descriptor_header *)&ss_ep_int_desc_comp,

        (struct usb_descriptor_header *)&std_as_out_if0_desc,
        (struct usb_descriptor_header *)&std_as_out_if1_desc,

        (struct usb_descriptor_header *)&as_out_hdr_desc,
        (struct usb_descriptor_header *)&as_out_fmt1_desc,
        (struct usb_descriptor_header *)&ss_epout_desc,
        (struct usb_descriptor_header *)&ss_epout_desc_comp,
        (struct usb_descriptor_header *)&as_iso_out_desc,
        (struct usb_descriptor_header *)&ss_epin_fback_desc,
        (struct usb_descriptor_header *)&ss_epin_fback_desc_comp,

        (struct usb_descriptor_header *)&std_as_in_if0_desc,
        (struct usb_descriptor_header *)&std_as_in_if1_desc,

        (struct usb_descriptor_header *)&as_in_hdr_desc,
        (struct usb_descriptor_header *)&as_in_fmt1_desc,
        (struct usb_descriptor_header *)&ss_epin_desc,
        (struct usb_descriptor_header *)&ss_epin_desc_comp,
        (struct usb_descriptor_header *)&as_iso_in_desc,
        NULL,
};

struct cntrl_cur_lay2 {
        __le16  wCUR;
};

struct cntrl_range_lay2 {
        __le16  wNumSubRanges;
        __le16  wMIN;
        __le16  wMAX;
        __le16  wRES;
} __packed;

struct cntrl_cur_lay3 {
        __le32  dCUR;
};

struct cntrl_subrange_lay3 {
        __le32  dMIN;
        __le32  dMAX;
        __le32  dRES;
} __packed;

#define ranges_lay3_size(c) (sizeof(c.wNumSubRanges)    \
                + le16_to_cpu(c.wNumSubRanges)          \
                * sizeof(struct cntrl_subrange_lay3))

#define DECLARE_UAC2_CNTRL_RANGES_LAY3(k, n)            \
        struct cntrl_ranges_lay3_##k {                  \
        __le16  wNumSubRanges;                          \
        struct cntrl_subrange_lay3 r[n];                \
} __packed

DECLARE_UAC2_CNTRL_RANGES_LAY3(srates, UAC_MAX_RATES);

static int get_max_srate(const int *srates)
{
        int i, max_srate = 0;

        for (i = 0; i < UAC_MAX_RATES; i++) {
                if (srates[i] == 0)
                        break;
                if (srates[i] > max_srate)
                        max_srate = srates[i];
        }
        return max_srate;
}

static int get_max_bw_for_bint(const struct f_uac2_opts *uac2_opts,
        u8 bint, unsigned int factor, bool is_playback)
{
        int chmask, srate, ssize;
        u16 max_size_bw;

        if (is_playback) {
                chmask = uac2_opts->p_chmask;
                srate = get_max_srate(uac2_opts->p_srates);
                ssize = uac2_opts->p_ssize;
        } else {
                chmask = uac2_opts->c_chmask;
                srate = get_max_srate(uac2_opts->c_srates);
                ssize = uac2_opts->c_ssize;
        }

        if (is_playback || (uac2_opts->c_sync == USB_ENDPOINT_SYNC_ASYNC)) {
                // playback is always async, capture only when configured
                // Win10 requires max packet size + 1 frame
                srate = srate * (1000 + uac2_opts->fb_max) / 1000;
                // updated srate is always bigger, therefore DIV_ROUND_UP always yields +1
                max_size_bw = num_channels(chmask) * ssize *
                        (DIV_ROUND_UP(srate, factor / (1 << (bint - 1))));
        } else {
                // adding 1 frame provision for Win10
                max_size_bw = num_channels(chmask) * ssize *
                        (DIV_ROUND_UP(srate, factor / (1 << (bint - 1))) + 1);
        }
        return max_size_bw;
}

static int set_ep_max_packet_size_bint(struct device *dev, const struct f_uac2_opts *uac2_opts,
        struct usb_endpoint_descriptor *ep_desc,
        enum usb_device_speed speed, bool is_playback)
{
        u16 max_size_bw, max_size_ep;
        u8 bint, opts_bint;
        char *dir;

        switch (speed) {
        case USB_SPEED_FULL:
                max_size_ep = 1023;
                // fixed
                bint = ep_desc->bInterval;
                max_size_bw = get_max_bw_for_bint(uac2_opts, bint, 1000, is_playback);
                break;

        case USB_SPEED_HIGH:
        case USB_SPEED_SUPER:
                max_size_ep = 1024;
                if (is_playback)
                        opts_bint = uac2_opts->p_hs_bint;
                else
                        opts_bint = uac2_opts->c_hs_bint;

                if (opts_bint > 0) {
                        /* fixed bint */
                        bint = opts_bint;
                        max_size_bw = get_max_bw_for_bint(uac2_opts, bint, 8000, is_playback);
                } else {
                        /* checking bInterval from 4 to 1 whether the required bandwidth fits */
                        for (bint = 4; bint > 0; --bint) {
                                max_size_bw = get_max_bw_for_bint(
                                        uac2_opts, bint, 8000, is_playback);
                                if (max_size_bw <= max_size_ep)
                                        break;
                        }
                }
                break;

        default:
                return -EINVAL;
        }

        if (is_playback)
                dir = "Playback";
        else
                dir = "Capture";

        if (max_size_bw <= max_size_ep)
                dev_dbg(dev,
                        "%s %s: Would use wMaxPacketSize %d and bInterval %d\n",
                        speed_names[speed], dir, max_size_bw, bint);
        else {
                dev_warn(dev,
                        "%s %s: Req. wMaxPacketSize %d at bInterval %d > max ISOC %d, may drop data!\n",
                        speed_names[speed], dir, max_size_bw, bint, max_size_ep);
                max_size_bw = max_size_ep;
        }

        ep_desc->wMaxPacketSize = cpu_to_le16(max_size_bw);
        ep_desc->bInterval = bint;

        return 0;
}

static struct uac2_feature_unit_descriptor *build_fu_desc(int chmask)
{
        struct uac2_feature_unit_descriptor *fu_desc;
        int channels = num_channels(chmask);
        int fu_desc_size = UAC2_DT_FEATURE_UNIT_SIZE(channels);

        fu_desc = kzalloc(fu_desc_size, GFP_KERNEL);
        if (!fu_desc)
                return NULL;

        fu_desc->bLength = fu_desc_size;
        fu_desc->bDescriptorType = USB_DT_CS_INTERFACE;

        fu_desc->bDescriptorSubtype = UAC_FEATURE_UNIT;

        /* bUnitID, bSourceID and bmaControls will be defined later */

        return fu_desc;
}

/* Use macro to overcome line length limitation */
#define USBDHDR(p) (struct usb_descriptor_header *)(p)

static void setup_headers(struct f_uac2_opts *opts,
                          struct usb_descriptor_header **headers,
                          enum usb_device_speed speed)
{
        struct usb_ss_ep_comp_descriptor *epout_desc_comp = NULL;
        struct usb_ss_ep_comp_descriptor *epin_desc_comp = NULL;
        struct usb_ss_ep_comp_descriptor *epin_fback_desc_comp = NULL;
        struct usb_ss_ep_comp_descriptor *ep_int_desc_comp = NULL;
        struct usb_endpoint_descriptor *epout_desc;
        struct usb_endpoint_descriptor *epin_desc;
        struct usb_endpoint_descriptor *epin_fback_desc;
        struct usb_endpoint_descriptor *ep_int_desc;
        int i;

        switch (speed) {
        case USB_SPEED_FULL:
                epout_desc = &fs_epout_desc;
                epin_desc = &fs_epin_desc;
                epin_fback_desc = &fs_epin_fback_desc;
                ep_int_desc = &fs_ep_int_desc;
                break;
        case USB_SPEED_HIGH:
                epout_desc = &hs_epout_desc;
                epin_desc = &hs_epin_desc;
                epin_fback_desc = &hs_epin_fback_desc;
                ep_int_desc = &hs_ep_int_desc;
                break;
        default:
                epout_desc = &ss_epout_desc;
                epin_desc = &ss_epin_desc;
                epout_desc_comp = &ss_epout_desc_comp;
                epin_desc_comp = &ss_epin_desc_comp;
                epin_fback_desc = &ss_epin_fback_desc;
                epin_fback_desc_comp = &ss_epin_fback_desc_comp;
                ep_int_desc = &ss_ep_int_desc;
                ep_int_desc_comp = &ss_ep_int_desc_comp;
        }

        i = 0;
        headers[i++] = USBDHDR(&iad_desc);
        headers[i++] = USBDHDR(&std_ac_if_desc);
        headers[i++] = USBDHDR(&ac_hdr_desc);
        if (EPIN_EN(opts))
                headers[i++] = USBDHDR(&in_clk_src_desc);
        if (EPOUT_EN(opts)) {
                headers[i++] = USBDHDR(&out_clk_src_desc);
                headers[i++] = USBDHDR(&usb_out_it_desc);

                if (FUOUT_EN(opts))
                        headers[i++] = USBDHDR(out_feature_unit_desc);
        }

        if (EPIN_EN(opts)) {
                headers[i++] = USBDHDR(&io_in_it_desc);

                if (FUIN_EN(opts))
                        headers[i++] = USBDHDR(in_feature_unit_desc);

                headers[i++] = USBDHDR(&usb_in_ot_desc);
        }

        if (EPOUT_EN(opts))
                headers[i++] = USBDHDR(&io_out_ot_desc);

        if (FUOUT_EN(opts) || FUIN_EN(opts)) {
                headers[i++] = USBDHDR(ep_int_desc);
                if (ep_int_desc_comp)
                        headers[i++] = USBDHDR(ep_int_desc_comp);
        }

        if (EPOUT_EN(opts)) {
                headers[i++] = USBDHDR(&std_as_out_if0_desc);
                headers[i++] = USBDHDR(&std_as_out_if1_desc);
                headers[i++] = USBDHDR(&as_out_hdr_desc);
                headers[i++] = USBDHDR(&as_out_fmt1_desc);
                headers[i++] = USBDHDR(epout_desc);
                if (epout_desc_comp)
                        headers[i++] = USBDHDR(epout_desc_comp);

                headers[i++] = USBDHDR(&as_iso_out_desc);

                if (EPOUT_FBACK_IN_EN(opts)) {
                        headers[i++] = USBDHDR(epin_fback_desc);
                        if (epin_fback_desc_comp)
                                headers[i++] = USBDHDR(epin_fback_desc_comp);
                }
        }

        if (EPIN_EN(opts)) {
                headers[i++] = USBDHDR(&std_as_in_if0_desc);
                headers[i++] = USBDHDR(&std_as_in_if1_desc);
                headers[i++] = USBDHDR(&as_in_hdr_desc);
                headers[i++] = USBDHDR(&as_in_fmt1_desc);
                headers[i++] = USBDHDR(epin_desc);
                if (epin_desc_comp)
                        headers[i++] = USBDHDR(epin_desc_comp);

                headers[i++] = USBDHDR(&as_iso_in_desc);
        }
        headers[i] = NULL;
}

static void setup_descriptor(struct f_uac2_opts *opts)
{
        /* patch descriptors */
        int i = 1; /* ID's start with 1 */

        if (EPOUT_EN(opts))
                usb_out_it_desc.bTerminalID = i++;
        if (EPIN_EN(opts))
                io_in_it_desc.bTerminalID = i++;
        if (EPOUT_EN(opts))
                io_out_ot_desc.bTerminalID = i++;
        if (EPIN_EN(opts))
                usb_in_ot_desc.bTerminalID = i++;
        if (FUOUT_EN(opts))
                out_feature_unit_desc->bUnitID = i++;
        if (FUIN_EN(opts))
                in_feature_unit_desc->bUnitID = i++;
        if (EPOUT_EN(opts))
                out_clk_src_desc.bClockID = i++;
        if (EPIN_EN(opts))
                in_clk_src_desc.bClockID = i++;

        usb_out_it_desc.bCSourceID = out_clk_src_desc.bClockID;

        if (FUIN_EN(opts)) {
                usb_in_ot_desc.bSourceID = in_feature_unit_desc->bUnitID;
                in_feature_unit_desc->bSourceID = io_in_it_desc.bTerminalID;
        } else {
                usb_in_ot_desc.bSourceID = io_in_it_desc.bTerminalID;
        }

        usb_in_ot_desc.bCSourceID = in_clk_src_desc.bClockID;
        io_in_it_desc.bCSourceID = in_clk_src_desc.bClockID;
        io_out_ot_desc.bCSourceID = out_clk_src_desc.bClockID;

        if (FUOUT_EN(opts)) {
                io_out_ot_desc.bSourceID = out_feature_unit_desc->bUnitID;
                out_feature_unit_desc->bSourceID = usb_out_it_desc.bTerminalID;
        } else {
                io_out_ot_desc.bSourceID = usb_out_it_desc.bTerminalID;
        }

        as_out_hdr_desc.bTerminalLink = usb_out_it_desc.bTerminalID;
        as_in_hdr_desc.bTerminalLink = usb_in_ot_desc.bTerminalID;

        iad_desc.bInterfaceCount = 1;
        ac_hdr_desc.wTotalLength = cpu_to_le16(sizeof(ac_hdr_desc));

        if (EPIN_EN(opts)) {
                u16 len = le16_to_cpu(ac_hdr_desc.wTotalLength);

                len += sizeof(in_clk_src_desc);
                len += sizeof(usb_in_ot_desc);

                if (FUIN_EN(opts))
                        len += in_feature_unit_desc->bLength;

                len += sizeof(io_in_it_desc);
                ac_hdr_desc.wTotalLength = cpu_to_le16(len);
                iad_desc.bInterfaceCount++;
        }
        if (EPOUT_EN(opts)) {
                u16 len = le16_to_cpu(ac_hdr_desc.wTotalLength);

                len += sizeof(out_clk_src_desc);
                len += sizeof(usb_out_it_desc);

                if (FUOUT_EN(opts))
                        len += out_feature_unit_desc->bLength;

                len += sizeof(io_out_ot_desc);
                ac_hdr_desc.wTotalLength = cpu_to_le16(len);
                iad_desc.bInterfaceCount++;
        }

        io_in_it_desc.wTerminalType = cpu_to_le16(opts->c_terminal_type);
        io_out_ot_desc.wTerminalType = cpu_to_le16(opts->p_terminal_type);

        setup_headers(opts, fs_audio_desc, USB_SPEED_FULL);
        setup_headers(opts, hs_audio_desc, USB_SPEED_HIGH);
        setup_headers(opts, ss_audio_desc, USB_SPEED_SUPER);
}

static int afunc_validate_opts(struct g_audio *agdev, struct device *dev)
{
        struct f_uac2_opts *opts = g_audio_to_uac2_opts(agdev);
        const char *msg = NULL;

        if (!opts->p_chmask && !opts->c_chmask)
                msg = "no playback and capture channels";
        else if (opts->p_chmask & ~UAC2_CHANNEL_MASK)
                msg = "unsupported playback channels mask";
        else if (opts->c_chmask & ~UAC2_CHANNEL_MASK)
                msg = "unsupported capture channels mask";
        else if ((opts->p_ssize < 1) || (opts->p_ssize > 4))
                msg = "incorrect playback sample size";
        else if ((opts->c_ssize < 1) || (opts->c_ssize > 4))
                msg = "incorrect capture sample size";
        else if (!opts->p_srates[0])
                msg = "incorrect playback sampling rate";
        else if (!opts->c_srates[0])
                msg = "incorrect capture sampling rate";

        else if (opts->p_volume_max <= opts->p_volume_min)
                msg = "incorrect playback volume max/min";
        else if (opts->c_volume_max <= opts->c_volume_min)
                msg = "incorrect capture volume max/min";
        else if (opts->p_volume_res <= 0)
                msg = "negative/zero playback volume resolution";
        else if (opts->c_volume_res <= 0)
                msg = "negative/zero capture volume resolution";

        else if ((opts->p_volume_max - opts->p_volume_min) % opts->p_volume_res)
                msg = "incorrect playback volume resolution";
        else if ((opts->c_volume_max - opts->c_volume_min) % opts->c_volume_res)
                msg = "incorrect capture volume resolution";

        else if ((opts->p_hs_bint < 0) || (opts->p_hs_bint > 4))
                msg = "incorrect playback HS/SS bInterval (1-4: fixed, 0: auto)";
        else if ((opts->c_hs_bint < 0) || (opts->c_hs_bint > 4))
                msg = "incorrect capture HS/SS bInterval (1-4: fixed, 0: auto)";

        if (msg) {
                dev_err(dev, "Error: %s\n", msg);
                return -EINVAL;
        }

        return 0;
}

static int
afunc_bind(struct usb_configuration *cfg, struct usb_function *fn)
{
        struct f_uac2 *uac2 = func_to_uac2(fn);
        struct g_audio *agdev = func_to_g_audio(fn);
        struct usb_composite_dev *cdev = cfg->cdev;
        struct usb_gadget *gadget = cdev->gadget;
        struct device *dev = &gadget->dev;
        struct f_uac2_opts *uac2_opts = g_audio_to_uac2_opts(agdev);
        struct usb_string *us;
        int ret;

        ret = afunc_validate_opts(agdev, dev);
        if (ret)
                return ret;

        strings_fn[STR_ASSOC].s = uac2_opts->function_name;
        strings_fn[STR_IF_CTRL].s = uac2_opts->if_ctrl_name;
        strings_fn[STR_CLKSRC_IN].s = uac2_opts->clksrc_in_name;
        strings_fn[STR_CLKSRC_OUT].s = uac2_opts->clksrc_out_name;

        strings_fn[STR_USB_IT].s = uac2_opts->c_it_name;
        strings_fn[STR_USB_IT_CH].s = uac2_opts->c_it_ch_name;
        strings_fn[STR_IO_OT].s = uac2_opts->c_ot_name;
        strings_fn[STR_FU_OUT].s = uac2_opts->c_fu_vol_name;
        strings_fn[STR_AS_OUT_ALT0].s = "Playback Inactive";
        strings_fn[STR_AS_OUT_ALT1].s = "Playback Active";

        strings_fn[STR_IO_IT].s = uac2_opts->p_it_name;
        strings_fn[STR_IO_IT_CH].s = uac2_opts->p_it_ch_name;
        strings_fn[STR_USB_OT].s = uac2_opts->p_ot_name;
        strings_fn[STR_FU_IN].s = uac2_opts->p_fu_vol_name;
        strings_fn[STR_AS_IN_ALT0].s = "Capture Inactive";
        strings_fn[STR_AS_IN_ALT1].s = "Capture Active";

        us = usb_gstrings_attach(cdev, fn_strings, ARRAY_SIZE(strings_fn));
        if (IS_ERR(us))
                return PTR_ERR(us);

        if (FUOUT_EN(uac2_opts)) {
                out_feature_unit_desc = build_fu_desc(uac2_opts->c_chmask);
                if (!out_feature_unit_desc)
                        return -ENOMEM;
        }
        if (FUIN_EN(uac2_opts)) {
                in_feature_unit_desc = build_fu_desc(uac2_opts->p_chmask);
                if (!in_feature_unit_desc) {
                        ret = -ENOMEM;
                        goto err_free_fu;
                }
        }

        iad_desc.iFunction = us[STR_ASSOC].id;
        std_ac_if_desc.iInterface = us[STR_IF_CTRL].id;
        in_clk_src_desc.iClockSource = us[STR_CLKSRC_IN].id;
        out_clk_src_desc.iClockSource = us[STR_CLKSRC_OUT].id;
        usb_out_it_desc.iTerminal = us[STR_USB_IT].id;
        usb_out_it_desc.iChannelNames = us[STR_USB_IT_CH].id;
        io_in_it_desc.iTerminal = us[STR_IO_IT].id;
        io_in_it_desc.iChannelNames = us[STR_IO_IT_CH].id;
        usb_in_ot_desc.iTerminal = us[STR_USB_OT].id;
        io_out_ot_desc.iTerminal = us[STR_IO_OT].id;
        std_as_out_if0_desc.iInterface = us[STR_AS_OUT_ALT0].id;
        std_as_out_if1_desc.iInterface = us[STR_AS_OUT_ALT1].id;
        std_as_in_if0_desc.iInterface = us[STR_AS_IN_ALT0].id;
        std_as_in_if1_desc.iInterface = us[STR_AS_IN_ALT1].id;

        if (FUOUT_EN(uac2_opts)) {
                u8 *i_feature = (u8 *)out_feature_unit_desc +
                                out_feature_unit_desc->bLength - 1;
                *i_feature = us[STR_FU_OUT].id;
        }
        if (FUIN_EN(uac2_opts)) {
                u8 *i_feature = (u8 *)in_feature_unit_desc +
                                in_feature_unit_desc->bLength - 1;
                *i_feature = us[STR_FU_IN].id;
        }


        /* Initialize the configurable parameters */
        usb_out_it_desc.bNrChannels = num_channels(uac2_opts->c_chmask);
        usb_out_it_desc.bmChannelConfig = cpu_to_le32(uac2_opts->c_chmask);
        io_in_it_desc.bNrChannels = num_channels(uac2_opts->p_chmask);
        io_in_it_desc.bmChannelConfig = cpu_to_le32(uac2_opts->p_chmask);
        as_out_hdr_desc.bNrChannels = num_channels(uac2_opts->c_chmask);
        as_out_hdr_desc.bmChannelConfig = cpu_to_le32(uac2_opts->c_chmask);
        as_in_hdr_desc.bNrChannels = num_channels(uac2_opts->p_chmask);
        as_in_hdr_desc.bmChannelConfig = cpu_to_le32(uac2_opts->p_chmask);
        as_out_fmt1_desc.bSubslotSize = uac2_opts->c_ssize;
        as_out_fmt1_desc.bBitResolution = uac2_opts->c_ssize * 8;
        as_in_fmt1_desc.bSubslotSize = uac2_opts->p_ssize;
        as_in_fmt1_desc.bBitResolution = uac2_opts->p_ssize * 8;
        if (FUOUT_EN(uac2_opts)) {
                __le32 *bma = (__le32 *)&out_feature_unit_desc->bmaControls[0];
                u32 control = 0;

                if (uac2_opts->c_mute_present)
                        control |= CONTROL_RDWR << FU_MUTE_CTRL;
                if (uac2_opts->c_volume_present)
                        control |= CONTROL_RDWR << FU_VOL_CTRL;
                *bma = cpu_to_le32(control);
        }
        if (FUIN_EN(uac2_opts)) {
                __le32 *bma = (__le32 *)&in_feature_unit_desc->bmaControls[0];
                u32 control = 0;

                if (uac2_opts->p_mute_present)
                        control |= CONTROL_RDWR << FU_MUTE_CTRL;
                if (uac2_opts->p_volume_present)
                        control |= CONTROL_RDWR << FU_VOL_CTRL;
                *bma = cpu_to_le32(control);
        }

        ret = usb_interface_id(cfg, fn);
        if (ret < 0) {
                dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
                goto err_free_fu;
        }
        iad_desc.bFirstInterface = ret;

        std_ac_if_desc.bInterfaceNumber = ret;
        uac2->ac_intf = ret;
        uac2->ac_alt = 0;

        if (EPOUT_EN(uac2_opts)) {
                ret = usb_interface_id(cfg, fn);
                if (ret < 0) {
                        dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
                        goto err_free_fu;
                }
                std_as_out_if0_desc.bInterfaceNumber = ret;
                std_as_out_if1_desc.bInterfaceNumber = ret;
                std_as_out_if1_desc.bNumEndpoints = 1;
                uac2->as_out_intf = ret;
                uac2->as_out_alt = 0;

                if (EPOUT_FBACK_IN_EN(uac2_opts)) {
                        fs_epout_desc.bmAttributes =
                          USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC;
                        hs_epout_desc.bmAttributes =
                          USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC;
                        ss_epout_desc.bmAttributes =
                          USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC;
                        std_as_out_if1_desc.bNumEndpoints++;
                } else {
                        fs_epout_desc.bmAttributes =
                          USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ADAPTIVE;
                        hs_epout_desc.bmAttributes =
                          USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ADAPTIVE;
                        ss_epout_desc.bmAttributes =
                          USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ADAPTIVE;
                }
        }

        if (EPIN_EN(uac2_opts)) {
                ret = usb_interface_id(cfg, fn);
                if (ret < 0) {
                        dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
                        goto err_free_fu;
                }
                std_as_in_if0_desc.bInterfaceNumber = ret;
                std_as_in_if1_desc.bInterfaceNumber = ret;
                uac2->as_in_intf = ret;
                uac2->as_in_alt = 0;
        }

        std_ac_if_desc.bNumEndpoints = 0;
        if (FUOUT_EN(uac2_opts) || FUIN_EN(uac2_opts)) {
                uac2->int_ep = usb_ep_autoconfig(gadget, &fs_ep_int_desc);
                if (!uac2->int_ep) {
                        dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
                        ret = -ENODEV;
                        goto err_free_fu;
                }

                std_ac_if_desc.bNumEndpoints = 1;
        }

        hs_epin_desc.bInterval = uac2_opts->p_hs_bint;
        ss_epin_desc.bInterval = uac2_opts->p_hs_bint;
        hs_epout_desc.bInterval = uac2_opts->c_hs_bint;
        ss_epout_desc.bInterval = uac2_opts->c_hs_bint;

        /* Calculate wMaxPacketSize according to audio bandwidth */
        ret = set_ep_max_packet_size_bint(dev, uac2_opts, &fs_epin_desc,
                                        USB_SPEED_FULL, true);
        if (ret < 0) {
                dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
                return ret;
        }

        ret = set_ep_max_packet_size_bint(dev, uac2_opts, &fs_epout_desc,
                                        USB_SPEED_FULL, false);
        if (ret < 0) {
                dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
                return ret;
        }

        ret = set_ep_max_packet_size_bint(dev, uac2_opts, &hs_epin_desc,
                                        USB_SPEED_HIGH, true);
        if (ret < 0) {
                dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
                return ret;
        }

        ret = set_ep_max_packet_size_bint(dev, uac2_opts, &hs_epout_desc,
                                        USB_SPEED_HIGH, false);
        if (ret < 0) {
                dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
                return ret;
        }

        ret = set_ep_max_packet_size_bint(dev, uac2_opts, &ss_epin_desc,
                                        USB_SPEED_SUPER, true);
        if (ret < 0) {
                dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
                return ret;
        }

        ret = set_ep_max_packet_size_bint(dev, uac2_opts, &ss_epout_desc,
                                        USB_SPEED_SUPER, false);
        if (ret < 0) {
                dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
                return ret;
        }

        if (EPOUT_EN(uac2_opts)) {
                agdev->out_ep = usb_ep_autoconfig(gadget, &fs_epout_desc);
                if (!agdev->out_ep) {
                        dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
                        ret = -ENODEV;
                        goto err_free_fu;
                }
                if (EPOUT_FBACK_IN_EN(uac2_opts)) {
                        agdev->in_ep_fback = usb_ep_autoconfig(gadget,
                                                       &fs_epin_fback_desc);
                        if (!agdev->in_ep_fback) {
                                dev_err(dev, "%s:%d Error!\n",
                                        __func__, __LINE__);
                                ret = -ENODEV;
                                goto err_free_fu;
                        }
                }
        }

        if (EPIN_EN(uac2_opts)) {
                agdev->in_ep = usb_ep_autoconfig(gadget, &fs_epin_desc);
                if (!agdev->in_ep) {
                        dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
                        ret = -ENODEV;
                        goto err_free_fu;
                }
        }

        agdev->in_ep_maxpsize = max_t(u16,
                                le16_to_cpu(fs_epin_desc.wMaxPacketSize),
                                le16_to_cpu(hs_epin_desc.wMaxPacketSize));
        agdev->out_ep_maxpsize = max_t(u16,
                                le16_to_cpu(fs_epout_desc.wMaxPacketSize),
                                le16_to_cpu(hs_epout_desc.wMaxPacketSize));

        agdev->in_ep_maxpsize = max_t(u16, agdev->in_ep_maxpsize,
                                le16_to_cpu(ss_epin_desc.wMaxPacketSize));
        agdev->out_ep_maxpsize = max_t(u16, agdev->out_ep_maxpsize,
                                le16_to_cpu(ss_epout_desc.wMaxPacketSize));

        ss_epin_desc_comp.wBytesPerInterval = ss_epin_desc.wMaxPacketSize;
        ss_epout_desc_comp.wBytesPerInterval = ss_epout_desc.wMaxPacketSize;

        // HS and SS endpoint addresses are copied from autoconfigured FS descriptors
        hs_ep_int_desc.bEndpointAddress = fs_ep_int_desc.bEndpointAddress;
        hs_epout_desc.bEndpointAddress = fs_epout_desc.bEndpointAddress;
        hs_epin_fback_desc.bEndpointAddress = fs_epin_fback_desc.bEndpointAddress;
        hs_epin_desc.bEndpointAddress = fs_epin_desc.bEndpointAddress;
        ss_epout_desc.bEndpointAddress = fs_epout_desc.bEndpointAddress;
        ss_epin_fback_desc.bEndpointAddress = fs_epin_fback_desc.bEndpointAddress;
        ss_epin_desc.bEndpointAddress = fs_epin_desc.bEndpointAddress;
        ss_ep_int_desc.bEndpointAddress = fs_ep_int_desc.bEndpointAddress;

        setup_descriptor(uac2_opts);

        ret = usb_assign_descriptors(fn, fs_audio_desc, hs_audio_desc, ss_audio_desc,
                                     ss_audio_desc);
        if (ret)
                goto err_free_fu;

        agdev->gadget = gadget;

        agdev->params.p_chmask = uac2_opts->p_chmask;
        memcpy(agdev->params.p_srates, uac2_opts->p_srates,
                        sizeof(agdev->params.p_srates));
        agdev->params.p_ssize = uac2_opts->p_ssize;
        if (FUIN_EN(uac2_opts)) {
                agdev->params.p_fu.id = USB_IN_FU_ID;
                agdev->params.p_fu.mute_present = uac2_opts->p_mute_present;
                agdev->params.p_fu.volume_present = uac2_opts->p_volume_present;
                agdev->params.p_fu.volume_min = uac2_opts->p_volume_min;
                agdev->params.p_fu.volume_max = uac2_opts->p_volume_max;
                agdev->params.p_fu.volume_res = uac2_opts->p_volume_res;
        }
        agdev->params.c_chmask = uac2_opts->c_chmask;
        memcpy(agdev->params.c_srates, uac2_opts->c_srates,
                        sizeof(agdev->params.c_srates));
        agdev->params.c_ssize = uac2_opts->c_ssize;
        if (FUOUT_EN(uac2_opts)) {
                agdev->params.c_fu.id = USB_OUT_FU_ID;
                agdev->params.c_fu.mute_present = uac2_opts->c_mute_present;
                agdev->params.c_fu.volume_present = uac2_opts->c_volume_present;
                agdev->params.c_fu.volume_min = uac2_opts->c_volume_min;
                agdev->params.c_fu.volume_max = uac2_opts->c_volume_max;
                agdev->params.c_fu.volume_res = uac2_opts->c_volume_res;
        }
        agdev->params.req_number = uac2_opts->req_number;
        agdev->params.fb_max = uac2_opts->fb_max;

        if (FUOUT_EN(uac2_opts) || FUIN_EN(uac2_opts))
    agdev->notify = afunc_notify;

        ret = g_audio_setup(agdev, "UAC2 PCM", "UAC2_Gadget");
        if (ret)
                goto err_free_descs;

        return 0;

err_free_descs:
        usb_free_all_descriptors(fn);
        agdev->gadget = NULL;
err_free_fu:
        kfree(out_feature_unit_desc);
        out_feature_unit_desc = NULL;
        kfree(in_feature_unit_desc);
        in_feature_unit_desc = NULL;
        return ret;
}

static void
afunc_notify_complete(struct usb_ep *_ep, struct usb_request *req)
{
        struct g_audio *agdev = req->context;
        struct f_uac2 *uac2 = func_to_uac2(&agdev->func);

        atomic_dec(&uac2->int_count);
        kfree(req->buf);
        usb_ep_free_request(_ep, req);
}

static int
afunc_notify(struct g_audio *agdev, int unit_id, int cs)
{
        struct f_uac2 *uac2 = func_to_uac2(&agdev->func);
        struct usb_request *req;
        struct uac2_interrupt_data_msg *msg;
        u16 w_index, w_value;
        int ret;

        if (!uac2->int_ep->enabled)
                return 0;

        if (atomic_inc_return(&uac2->int_count) > UAC2_DEF_INT_REQ_NUM) {
                atomic_dec(&uac2->int_count);
                return 0;
        }

        req = usb_ep_alloc_request(uac2->int_ep, GFP_ATOMIC);
        if (req == NULL) {
                ret = -ENOMEM;
                goto err_dec_int_count;
        }

        msg = kzalloc_obj(*msg, GFP_ATOMIC);
        if (msg == NULL) {
                ret = -ENOMEM;
                goto err_free_request;
        }

        w_index = unit_id << 8 | uac2->ac_intf;
        w_value = cs << 8;

        msg->bInfo = 0; /* Non-vendor, interface interrupt */
        msg->bAttribute = UAC2_CS_CUR;
        msg->wIndex = cpu_to_le16(w_index);
        msg->wValue = cpu_to_le16(w_value);

        req->length = sizeof(*msg);
        req->buf = msg;
        req->context = agdev;
        req->complete = afunc_notify_complete;

        ret = usb_ep_queue(uac2->int_ep, req, GFP_ATOMIC);

        if (ret)
                goto err_free_msg;

        return 0;

err_free_msg:
        kfree(msg);
err_free_request:
        usb_ep_free_request(uac2->int_ep, req);
err_dec_int_count:
        atomic_dec(&uac2->int_count);

        return ret;
}

static int
afunc_set_alt(struct usb_function *fn, unsigned intf, unsigned alt)
{
        struct usb_composite_dev *cdev = fn->config->cdev;
        struct f_uac2 *uac2 = func_to_uac2(fn);
        struct g_audio *agdev = func_to_g_audio(fn);
        struct usb_gadget *gadget = cdev->gadget;
        struct device *dev = &gadget->dev;
        int ret = 0;

        /* No i/f has more than 2 alt settings */
        if (alt > 1) {
                dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
                return -EINVAL;
        }

        if (intf == uac2->ac_intf) {
                /* Control I/f has only 1 AltSetting - 0 */
                if (alt) {
                        dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
                        return -EINVAL;
                }

                /* restart interrupt endpoint */
                if (uac2->int_ep) {
                        usb_ep_disable(uac2->int_ep);
                        config_ep_by_speed(gadget, &agdev->func, uac2->int_ep);
                        usb_ep_enable(uac2->int_ep);
                }

                return 0;
        }

        if (intf == uac2->as_out_intf) {
                uac2->as_out_alt = alt;

                if (alt)
                        ret = u_audio_start_capture(&uac2->g_audio);
                else
                        u_audio_stop_capture(&uac2->g_audio);
        } else if (intf == uac2->as_in_intf) {
                uac2->as_in_alt = alt;

                if (alt)
                        ret = u_audio_start_playback(&uac2->g_audio);
                else
                        u_audio_stop_playback(&uac2->g_audio);
        } else {
                dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
                return -EINVAL;
        }

        return ret;
}

static int
afunc_get_alt(struct usb_function *fn, unsigned intf)
{
        struct f_uac2 *uac2 = func_to_uac2(fn);
        struct g_audio *agdev = func_to_g_audio(fn);

        if (intf == uac2->ac_intf)
                return uac2->ac_alt;
        else if (intf == uac2->as_out_intf)
                return uac2->as_out_alt;
        else if (intf == uac2->as_in_intf)
                return uac2->as_in_alt;
        else
                dev_err(&agdev->gadget->dev,
                        "%s:%d Invalid Interface %d!\n",
                        __func__, __LINE__, intf);

        return -EINVAL;
}

static void
afunc_disable(struct usb_function *fn)
{
        struct f_uac2 *uac2 = func_to_uac2(fn);

        uac2->as_in_alt = 0;
        uac2->as_out_alt = 0;
        u_audio_stop_capture(&uac2->g_audio);
        u_audio_stop_playback(&uac2->g_audio);
        if (uac2->int_ep)
                usb_ep_disable(uac2->int_ep);
}

static void
afunc_suspend(struct usb_function *fn)
{
        struct f_uac2 *uac2 = func_to_uac2(fn);

        u_audio_suspend(&uac2->g_audio);
}

static int
in_rq_cur(struct usb_function *fn, const struct usb_ctrlrequest *cr)
{
        struct usb_request *req = fn->config->cdev->req;
        struct g_audio *agdev = func_to_g_audio(fn);
        struct f_uac2_opts *opts = g_audio_to_uac2_opts(agdev);
        u16 w_length = le16_to_cpu(cr->wLength);
        u16 w_index = le16_to_cpu(cr->wIndex);
        u16 w_value = le16_to_cpu(cr->wValue);
        u8 entity_id = (w_index >> 8) & 0xff;
        u8 control_selector = w_value >> 8;
        int value = -EOPNOTSUPP;
        u32 p_srate, c_srate;

        u_audio_get_playback_srate(agdev, &p_srate);
        u_audio_get_capture_srate(agdev, &c_srate);

        if ((entity_id == USB_IN_CLK_ID) || (entity_id == USB_OUT_CLK_ID)) {
                if (control_selector == UAC2_CS_CONTROL_SAM_FREQ) {
                        struct cntrl_cur_lay3 c;

                        memset(&c, 0, sizeof(struct cntrl_cur_lay3));

                        if (entity_id == USB_IN_CLK_ID)
                                c.dCUR = cpu_to_le32(p_srate);
                        else if (entity_id == USB_OUT_CLK_ID)
                                c.dCUR = cpu_to_le32(c_srate);

                        value = min_t(unsigned int, w_length, sizeof(c));
                        memcpy(req->buf, &c, value);
                } else if (control_selector == UAC2_CS_CONTROL_CLOCK_VALID) {
                        *(u8 *)req->buf = 1;
                        value = min_t(unsigned int, w_length, 1);
                } else {
                        dev_err(&agdev->gadget->dev,
                                "%s:%d control_selector=%d TODO!\n",
                                __func__, __LINE__, control_selector);
                }
        } else if ((FUIN_EN(opts) && (entity_id == USB_IN_FU_ID)) ||
                        (FUOUT_EN(opts) && (entity_id == USB_OUT_FU_ID))) {
                unsigned int is_playback = 0;

                if (FUIN_EN(opts) && (entity_id == USB_IN_FU_ID))
                        is_playback = 1;

                if (control_selector == UAC_FU_MUTE) {
                        unsigned int mute;

                        u_audio_get_mute(agdev, is_playback, &mute);

                        *(u8 *)req->buf = mute;
                        value = min_t(unsigned int, w_length, 1);
                } else if (control_selector == UAC_FU_VOLUME) {
                        struct cntrl_cur_lay2 c;
                        s16 volume;

                        memset(&c, 0, sizeof(struct cntrl_cur_lay2));

                        u_audio_get_volume(agdev, is_playback, &volume);
                        c.wCUR = cpu_to_le16(volume);

                        value = min_t(unsigned int, w_length, sizeof(c));
                        memcpy(req->buf, &c, value);
                } else {
                        dev_err(&agdev->gadget->dev,
                                "%s:%d control_selector=%d TODO!\n",
                                __func__, __LINE__, control_selector);
                }
        } else {
                dev_err(&agdev->gadget->dev,
                        "%s:%d entity_id=%d control_selector=%d TODO!\n",
                        __func__, __LINE__, entity_id, control_selector);
        }

        return value;
}

static int
in_rq_range(struct usb_function *fn, const struct usb_ctrlrequest *cr)
{
        struct usb_request *req = fn->config->cdev->req;
        struct g_audio *agdev = func_to_g_audio(fn);
        struct f_uac2_opts *opts = g_audio_to_uac2_opts(agdev);
        u16 w_length = le16_to_cpu(cr->wLength);
        u16 w_index = le16_to_cpu(cr->wIndex);
        u16 w_value = le16_to_cpu(cr->wValue);
        u8 entity_id = (w_index >> 8) & 0xff;
        u8 control_selector = w_value >> 8;
        int value = -EOPNOTSUPP;

        if ((entity_id == USB_IN_CLK_ID) || (entity_id == USB_OUT_CLK_ID)) {
                if (control_selector == UAC2_CS_CONTROL_SAM_FREQ) {
                        struct cntrl_ranges_lay3_srates rs;
                        int i;
                        int wNumSubRanges = 0;
                        int srate;
                        int *srates;

                        if (entity_id == USB_IN_CLK_ID)
                                srates = opts->p_srates;
                        else if (entity_id == USB_OUT_CLK_ID)
                                srates = opts->c_srates;
                        else
                                return -EOPNOTSUPP;
                        for (i = 0; i < UAC_MAX_RATES; i++) {
                                srate = srates[i];
                                if (srate == 0)
                                        break;

                                rs.r[wNumSubRanges].dMIN = cpu_to_le32(srate);
                                rs.r[wNumSubRanges].dMAX = cpu_to_le32(srate);
                                rs.r[wNumSubRanges].dRES = 0;
                                wNumSubRanges++;
                                dev_dbg(&agdev->gadget->dev,
                                        "%s(): clk %d: rate ID %d: %d\n",
                                        __func__, entity_id, wNumSubRanges, srate);
                        }
                        rs.wNumSubRanges = cpu_to_le16(wNumSubRanges);
                        value = min_t(unsigned int, w_length, ranges_lay3_size(rs));
                        dev_dbg(&agdev->gadget->dev, "%s(): sending %d rates, size %d\n",
                                __func__, rs.wNumSubRanges, value);
                        memcpy(req->buf, &rs, value);
                } else {
                        dev_err(&agdev->gadget->dev,
                                "%s:%d control_selector=%d TODO!\n",
                                __func__, __LINE__, control_selector);
                }
        } else if ((FUIN_EN(opts) && (entity_id == USB_IN_FU_ID)) ||
                        (FUOUT_EN(opts) && (entity_id == USB_OUT_FU_ID))) {
                unsigned int is_playback = 0;

                if (FUIN_EN(opts) && (entity_id == USB_IN_FU_ID))
                        is_playback = 1;

                if (control_selector == UAC_FU_VOLUME) {
                        struct cntrl_range_lay2 r;
                        s16 max_db, min_db, res_db;

                        if (is_playback) {
                                max_db = opts->p_volume_max;
                                min_db = opts->p_volume_min;
                                res_db = opts->p_volume_res;
                        } else {
                                max_db = opts->c_volume_max;
                                min_db = opts->c_volume_min;
                                res_db = opts->c_volume_res;
                        }

                        r.wMAX = cpu_to_le16(max_db);
                        r.wMIN = cpu_to_le16(min_db);
                        r.wRES = cpu_to_le16(res_db);
                        r.wNumSubRanges = cpu_to_le16(1);

                        value = min_t(unsigned int, w_length, sizeof(r));
                        memcpy(req->buf, &r, value);
                } else {
                        dev_err(&agdev->gadget->dev,
                                "%s:%d control_selector=%d TODO!\n",
                                __func__, __LINE__, control_selector);
                }
        } else {
                dev_err(&agdev->gadget->dev,
                        "%s:%d entity_id=%d control_selector=%d TODO!\n",
                        __func__, __LINE__, entity_id, control_selector);
        }

        return value;
}

static int
ac_rq_in(struct usb_function *fn, const struct usb_ctrlrequest *cr)
{
        if (cr->bRequest == UAC2_CS_CUR)
                return in_rq_cur(fn, cr);
        else if (cr->bRequest == UAC2_CS_RANGE)
                return in_rq_range(fn, cr);
        else
                return -EOPNOTSUPP;
}

static void uac2_cs_control_sam_freq(struct usb_ep *ep, struct usb_request *req)
{
        struct usb_function *fn = ep->driver_data;
        struct g_audio *agdev = func_to_g_audio(fn);
        struct f_uac2 *uac2 = func_to_uac2(fn);
        u32 val;

        if (req->actual != 4)
                return;

        val = le32_to_cpu(*((__le32 *)req->buf));
        dev_dbg(&agdev->gadget->dev, "%s val: %d.\n", __func__, val);
        if (uac2->clock_id == USB_IN_CLK_ID) {
                u_audio_set_playback_srate(agdev, val);
        } else if (uac2->clock_id == USB_OUT_CLK_ID) {
                u_audio_set_capture_srate(agdev, val);
        }
}

static void
out_rq_cur_complete(struct usb_ep *ep, struct usb_request *req)
{
        struct g_audio *agdev = req->context;
        struct usb_composite_dev *cdev = agdev->func.config->cdev;
        struct f_uac2_opts *opts = g_audio_to_uac2_opts(agdev);
        struct f_uac2 *uac2 = func_to_uac2(&agdev->func);
        struct usb_ctrlrequest *cr = &uac2->setup_cr;
        u16 w_index = le16_to_cpu(cr->wIndex);
        u16 w_value = le16_to_cpu(cr->wValue);
        u8 entity_id = (w_index >> 8) & 0xff;
        u8 control_selector = w_value >> 8;

        if (req->status != 0) {
                dev_dbg(&cdev->gadget->dev, "completion err %d\n", req->status);
                return;
        }

        if ((FUIN_EN(opts) && (entity_id == USB_IN_FU_ID)) ||
                (FUOUT_EN(opts) && (entity_id == USB_OUT_FU_ID))) {
                unsigned int is_playback = 0;

                if (FUIN_EN(opts) && (entity_id == USB_IN_FU_ID))
                        is_playback = 1;

                if (control_selector == UAC_FU_MUTE) {
                        u8 mute = *(u8 *)req->buf;

                        u_audio_set_mute(agdev, is_playback, mute);

                        return;
                } else if (control_selector == UAC_FU_VOLUME) {
                        struct cntrl_cur_lay2 *c = req->buf;
                        s16 volume;

                        volume = le16_to_cpu(c->wCUR);
                        u_audio_set_volume(agdev, is_playback, volume);

                        return;
                } else {
                        dev_err(&agdev->gadget->dev,
                                "%s:%d control_selector=%d TODO!\n",
                                __func__, __LINE__, control_selector);
                        usb_ep_set_halt(ep);
                }
        }
}

static int
out_rq_cur(struct usb_function *fn, const struct usb_ctrlrequest *cr)
{
        struct usb_composite_dev *cdev = fn->config->cdev;
        struct usb_request *req = fn->config->cdev->req;
        struct g_audio *agdev = func_to_g_audio(fn);
        struct f_uac2_opts *opts = g_audio_to_uac2_opts(agdev);
        struct f_uac2 *uac2 = func_to_uac2(fn);
        u16 w_length = le16_to_cpu(cr->wLength);
        u16 w_index = le16_to_cpu(cr->wIndex);
        u16 w_value = le16_to_cpu(cr->wValue);
        u8 entity_id = (w_index >> 8) & 0xff;
        u8 control_selector = w_value >> 8;
        u8 clock_id = w_index >> 8;

        if ((entity_id == USB_IN_CLK_ID) || (entity_id == USB_OUT_CLK_ID)) {
                if (control_selector == UAC2_CS_CONTROL_SAM_FREQ) {
                        dev_dbg(&agdev->gadget->dev,
                                "control_selector UAC2_CS_CONTROL_SAM_FREQ, clock: %d\n", clock_id);
                        cdev->gadget->ep0->driver_data = fn;
                        uac2->clock_id = clock_id;
                        req->complete = uac2_cs_control_sam_freq;
                        return w_length;
                }
        } else if ((FUIN_EN(opts) && (entity_id == USB_IN_FU_ID)) ||
                        (FUOUT_EN(opts) && (entity_id == USB_OUT_FU_ID))) {
                memcpy(&uac2->setup_cr, cr, sizeof(*cr));
                req->context = agdev;
                req->complete = out_rq_cur_complete;

                return w_length;
        } else {
                dev_err(&agdev->gadget->dev,
                        "%s:%d entity_id=%d control_selector=%d TODO!\n",
                        __func__, __LINE__, entity_id, control_selector);
        }
        return -EOPNOTSUPP;
}

static int
setup_rq_inf(struct usb_function *fn, const struct usb_ctrlrequest *cr)
{
        struct f_uac2 *uac2 = func_to_uac2(fn);
        struct g_audio *agdev = func_to_g_audio(fn);
        u16 w_index = le16_to_cpu(cr->wIndex);
        u8 intf = w_index & 0xff;

        if (intf != uac2->ac_intf) {
                dev_err(&agdev->gadget->dev,
                        "%s:%d Error!\n", __func__, __LINE__);
                return -EOPNOTSUPP;
        }

        if (cr->bRequestType & USB_DIR_IN)
                return ac_rq_in(fn, cr);
        else if (cr->bRequest == UAC2_CS_CUR)
                return out_rq_cur(fn, cr);

        return -EOPNOTSUPP;
}

static int
afunc_setup(struct usb_function *fn, const struct usb_ctrlrequest *cr)
{
        struct usb_composite_dev *cdev = fn->config->cdev;
        struct g_audio *agdev = func_to_g_audio(fn);
        struct usb_request *req = cdev->req;
        u16 w_length = le16_to_cpu(cr->wLength);
        int value = -EOPNOTSUPP;

        /* Only Class specific requests are supposed to reach here */
        if ((cr->bRequestType & USB_TYPE_MASK) != USB_TYPE_CLASS)
                return -EOPNOTSUPP;

        if ((cr->bRequestType & USB_RECIP_MASK) == USB_RECIP_INTERFACE)
                value = setup_rq_inf(fn, cr);
        else
                dev_err(&agdev->gadget->dev, "%s:%d Error!\n",
                                __func__, __LINE__);

        if (value >= 0) {
                req->length = value;
                req->zero = value < w_length;
                value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
                if (value < 0) {
                        dev_err(&agdev->gadget->dev,
                                "%s:%d Error!\n", __func__, __LINE__);
                        req->status = 0;
                }
        }

        return value;
}

static inline struct f_uac2_opts *to_f_uac2_opts(struct config_item *item)
{
        return container_of(to_config_group(item), struct f_uac2_opts,
                            func_inst.group);
}

static void f_uac2_attr_release(struct config_item *item)
{
        struct f_uac2_opts *opts = to_f_uac2_opts(item);

        usb_put_function_instance(&opts->func_inst);
}

static const struct configfs_item_operations f_uac2_item_ops = {
        .release        = f_uac2_attr_release,
};

#define uac2_kstrtou8 kstrtou8
#define uac2_kstrtou32 kstrtou32
#define uac2_kstrtos16 kstrtos16
#define uac2_kstrtobool(s, base, res) kstrtobool((s), (res))

static const char *u8_fmt = "%u\n";
static const char *u32_fmt = "%u\n";
static const char *s16_fmt = "%hd\n";
static const char *bool_fmt = "%u\n";

#define UAC2_ATTRIBUTE(type, name)                                      \
static ssize_t f_uac2_opts_##name##_show(struct config_item *item,      \
                                         char *page)                    \
{                                                                       \
        struct f_uac2_opts *opts = to_f_uac2_opts(item);                \
        int result;                                                     \
                                                                        \
        mutex_lock(&opts->lock);                                        \
        result = sprintf(page, type##_fmt, opts->name);                 \
        mutex_unlock(&opts->lock);                                      \
                                                                        \
        return result;                                                  \
}                                                                       \
                                                                        \
static ssize_t f_uac2_opts_##name##_store(struct config_item *item,     \
                                          const char *page, size_t len) \
{                                                                       \
        struct f_uac2_opts *opts = to_f_uac2_opts(item);                \
        int ret;                                                        \
        type num;                                                       \
                                                                        \
        mutex_lock(&opts->lock);                                        \
        if (opts->refcnt) {                                             \
                ret = -EBUSY;                                           \
                goto end;                                               \
        }                                                               \
                                                                        \
        ret = uac2_kstrto##type(page, 0, &num);                         \
        if (ret)                                                        \
                goto end;                                               \
                                                                        \
        opts->name = num;                                               \
        ret = len;                                                      \
                                                                        \
end:                                                                    \
        mutex_unlock(&opts->lock);                                      \
        return ret;                                                     \
}                                                                       \
                                                                        \
CONFIGFS_ATTR(f_uac2_opts_, name)

#define UAC2_ATTRIBUTE_SYNC(name)                                       \
static ssize_t f_uac2_opts_##name##_show(struct config_item *item,      \
                                         char *page)                    \
{                                                                       \
        struct f_uac2_opts *opts = to_f_uac2_opts(item);                \
        int result;                                                     \
        char *str;                                                      \
                                                                        \
        mutex_lock(&opts->lock);                                        \
        switch (opts->name) {                                           \
        case USB_ENDPOINT_SYNC_ASYNC:                                   \
                str = "async";                                          \
                break;                                                  \
        case USB_ENDPOINT_SYNC_ADAPTIVE:                                \
                str = "adaptive";                                       \
                break;                                                  \
        default:                                                        \
                str = "unknown";                                        \
                break;                                                  \
        }                                                               \
        result = sprintf(page, "%s\n", str);                            \
        mutex_unlock(&opts->lock);                                      \
                                                                        \
        return result;                                                  \
}                                                                       \
                                                                        \
static ssize_t f_uac2_opts_##name##_store(struct config_item *item,     \
                                          const char *page, size_t len) \
{                                                                       \
        struct f_uac2_opts *opts = to_f_uac2_opts(item);                \
        int ret = 0;                                                    \
                                                                        \
        mutex_lock(&opts->lock);                                        \
        if (opts->refcnt) {                                             \
                ret = -EBUSY;                                           \
                goto end;                                               \
        }                                                               \
                                                                        \
        if (!strncmp(page, "async", 5))                                 \
                opts->name = USB_ENDPOINT_SYNC_ASYNC;                   \
        else if (!strncmp(page, "adaptive", 8))                         \
                opts->name = USB_ENDPOINT_SYNC_ADAPTIVE;                \
        else {                                                          \
                ret = -EINVAL;                                          \
                goto end;                                               \
        }                                                               \
                                                                        \
        ret = len;                                                      \
                                                                        \
end:                                                                    \
        mutex_unlock(&opts->lock);                                      \
        return ret;                                                     \
}                                                                       \
                                                                        \
CONFIGFS_ATTR(f_uac2_opts_, name)

#define UAC2_RATE_ATTRIBUTE(name)                                       \
static ssize_t f_uac2_opts_##name##_show(struct config_item *item,      \
                                         char *page)                    \
{                                                                       \
        struct f_uac2_opts *opts = to_f_uac2_opts(item);                \
        int result = 0;                                                 \
        int i;                                                          \
                                                                        \
        mutex_lock(&opts->lock);                                        \
        page[0] = '\0';                                                 \
        for (i = 0; i < UAC_MAX_RATES; i++) {                           \
                if (opts->name##s[i] == 0)                              \
                        break;                                          \
                result += sprintf(page + strlen(page), "%u,",           \
                                opts->name##s[i]);                      \
        }                                                               \
        if (strlen(page) > 0)                                           \
                page[strlen(page) - 1] = '\n';                          \
        mutex_unlock(&opts->lock);                                      \
                                                                        \
        return result;                                                  \
}                                                                       \
                                                                        \
static ssize_t f_uac2_opts_##name##_store(struct config_item *item,     \
                                          const char *page, size_t len) \
{                                                                       \
        struct f_uac2_opts *opts = to_f_uac2_opts(item);                \
        char *split_page = NULL;                                        \
        int ret = -EINVAL;                                              \
        char *token;                                                    \
        u32 num;                                                        \
        int i;                                                          \
                                                                        \
        mutex_lock(&opts->lock);                                        \
        if (opts->refcnt) {                                             \
                ret = -EBUSY;                                           \
                goto end;                                               \
        }                                                               \
                                                                        \
        i = 0;                                                          \
        memset(opts->name##s, 0x00, sizeof(opts->name##s));             \
        split_page = kstrdup(page, GFP_KERNEL);                         \
        while ((token = strsep(&split_page, ",")) != NULL) {            \
                ret = kstrtou32(token, 0, &num);                        \
                if (ret)                                                \
                        goto end;                                       \
                                                                        \
                opts->name##s[i++] = num;                               \
                ret = len;                                              \
        };                                                              \
                                                                        \
end:                                                                    \
        kfree(split_page);                                              \
        mutex_unlock(&opts->lock);                                      \
        return ret;                                                     \
}                                                                       \
                                                                        \
CONFIGFS_ATTR(f_uac2_opts_, name)

#define UAC2_ATTRIBUTE_STRING(name)                                     \
static ssize_t f_uac2_opts_##name##_show(struct config_item *item,      \
                                         char *page)                    \
{                                                                       \
        struct f_uac2_opts *opts = to_f_uac2_opts(item);                \
        int result;                                                     \
                                                                        \
        mutex_lock(&opts->lock);                                        \
        result = sysfs_emit(page, "%s", opts->name);                    \
        mutex_unlock(&opts->lock);                                      \
                                                                        \
        return result;                                                  \
}                                                                       \
                                                                        \
static ssize_t f_uac2_opts_##name##_store(struct config_item *item,     \
                                          const char *page, size_t len) \
{                                                                       \
        struct f_uac2_opts *opts = to_f_uac2_opts(item);                \
        int ret = len;                                                  \
                                                                        \
        mutex_lock(&opts->lock);                                        \
        if (opts->refcnt) {                                             \
                ret = -EBUSY;                                           \
                goto end;                                               \
        }                                                               \
                                                                        \
        if (len && page[len - 1] == '\n')                               \
                len--;                                                  \
                                                                        \
        scnprintf(opts->name, min(sizeof(opts->name), len + 1),         \
                  "%s", page);                                          \
                                                                        \
end:                                                                    \
        mutex_unlock(&opts->lock);                                      \
        return ret;                                                     \
}                                                                       \
                                                                        \
CONFIGFS_ATTR(f_uac2_opts_, name)

UAC2_ATTRIBUTE(u32, p_chmask);
UAC2_RATE_ATTRIBUTE(p_srate);
UAC2_ATTRIBUTE(u32, p_ssize);
UAC2_ATTRIBUTE(u8, p_hs_bint);
UAC2_ATTRIBUTE(u32, c_chmask);
UAC2_RATE_ATTRIBUTE(c_srate);
UAC2_ATTRIBUTE_SYNC(c_sync);
UAC2_ATTRIBUTE(u32, c_ssize);
UAC2_ATTRIBUTE(u8, c_hs_bint);
UAC2_ATTRIBUTE(u32, req_number);

UAC2_ATTRIBUTE(bool, p_mute_present);
UAC2_ATTRIBUTE(bool, p_volume_present);
UAC2_ATTRIBUTE(s16, p_volume_min);
UAC2_ATTRIBUTE(s16, p_volume_max);
UAC2_ATTRIBUTE(s16, p_volume_res);

UAC2_ATTRIBUTE(bool, c_mute_present);
UAC2_ATTRIBUTE(bool, c_volume_present);
UAC2_ATTRIBUTE(s16, c_volume_min);
UAC2_ATTRIBUTE(s16, c_volume_max);
UAC2_ATTRIBUTE(s16, c_volume_res);
UAC2_ATTRIBUTE(u32, fb_max);
UAC2_ATTRIBUTE_STRING(function_name);
UAC2_ATTRIBUTE_STRING(if_ctrl_name);
UAC2_ATTRIBUTE_STRING(clksrc_in_name);
UAC2_ATTRIBUTE_STRING(clksrc_out_name);

UAC2_ATTRIBUTE_STRING(p_it_name);
UAC2_ATTRIBUTE_STRING(p_it_ch_name);
UAC2_ATTRIBUTE_STRING(p_ot_name);
UAC2_ATTRIBUTE_STRING(p_fu_vol_name);

UAC2_ATTRIBUTE_STRING(c_it_name);
UAC2_ATTRIBUTE_STRING(c_it_ch_name);
UAC2_ATTRIBUTE_STRING(c_ot_name);
UAC2_ATTRIBUTE_STRING(c_fu_vol_name);

UAC2_ATTRIBUTE(s16, p_terminal_type);
UAC2_ATTRIBUTE(s16, c_terminal_type);


static struct configfs_attribute *f_uac2_attrs[] = {
        &f_uac2_opts_attr_p_chmask,
        &f_uac2_opts_attr_p_srate,
        &f_uac2_opts_attr_p_ssize,
        &f_uac2_opts_attr_p_hs_bint,
        &f_uac2_opts_attr_c_chmask,
        &f_uac2_opts_attr_c_srate,
        &f_uac2_opts_attr_c_ssize,
        &f_uac2_opts_attr_c_hs_bint,
        &f_uac2_opts_attr_c_sync,
        &f_uac2_opts_attr_req_number,
        &f_uac2_opts_attr_fb_max,

        &f_uac2_opts_attr_p_mute_present,
        &f_uac2_opts_attr_p_volume_present,
        &f_uac2_opts_attr_p_volume_min,
        &f_uac2_opts_attr_p_volume_max,
        &f_uac2_opts_attr_p_volume_res,

        &f_uac2_opts_attr_c_mute_present,
        &f_uac2_opts_attr_c_volume_present,
        &f_uac2_opts_attr_c_volume_min,
        &f_uac2_opts_attr_c_volume_max,
        &f_uac2_opts_attr_c_volume_res,

        &f_uac2_opts_attr_function_name,
        &f_uac2_opts_attr_if_ctrl_name,
        &f_uac2_opts_attr_clksrc_in_name,
        &f_uac2_opts_attr_clksrc_out_name,

        &f_uac2_opts_attr_p_it_name,
        &f_uac2_opts_attr_p_it_ch_name,
        &f_uac2_opts_attr_p_ot_name,
        &f_uac2_opts_attr_p_fu_vol_name,

        &f_uac2_opts_attr_c_it_name,
        &f_uac2_opts_attr_c_it_ch_name,
        &f_uac2_opts_attr_c_ot_name,
        &f_uac2_opts_attr_c_fu_vol_name,

        &f_uac2_opts_attr_p_terminal_type,
        &f_uac2_opts_attr_c_terminal_type,

        NULL,
};

static const struct config_item_type f_uac2_func_type = {
        .ct_item_ops    = &f_uac2_item_ops,
        .ct_attrs       = f_uac2_attrs,
        .ct_owner       = THIS_MODULE,
};

static void afunc_free_inst(struct usb_function_instance *f)
{
        struct f_uac2_opts *opts;

        opts = container_of(f, struct f_uac2_opts, func_inst);
        kfree(opts);
}

static struct usb_function_instance *afunc_alloc_inst(void)
{
        struct f_uac2_opts *opts;

        opts = kzalloc_obj(*opts);
        if (!opts)
                return ERR_PTR(-ENOMEM);

        mutex_init(&opts->lock);
        opts->func_inst.free_func_inst = afunc_free_inst;

        config_group_init_type_name(&opts->func_inst.group, "",
                                    &f_uac2_func_type);

        opts->p_chmask = UAC2_DEF_PCHMASK;
        opts->p_srates[0] = UAC2_DEF_PSRATE;
        opts->p_ssize = UAC2_DEF_PSSIZE;
        opts->p_hs_bint = UAC2_DEF_PHSBINT;
        opts->c_chmask = UAC2_DEF_CCHMASK;
        opts->c_srates[0] = UAC2_DEF_CSRATE;
        opts->c_ssize = UAC2_DEF_CSSIZE;
        opts->c_hs_bint = UAC2_DEF_CHSBINT;
        opts->c_sync = UAC2_DEF_CSYNC;

        opts->p_mute_present = UAC2_DEF_MUTE_PRESENT;
        opts->p_volume_present = UAC2_DEF_VOLUME_PRESENT;
        opts->p_volume_min = UAC2_DEF_MIN_DB;
        opts->p_volume_max = UAC2_DEF_MAX_DB;
        opts->p_volume_res = UAC2_DEF_RES_DB;

        opts->c_mute_present = UAC2_DEF_MUTE_PRESENT;
        opts->c_volume_present = UAC2_DEF_VOLUME_PRESENT;
        opts->c_volume_min = UAC2_DEF_MIN_DB;
        opts->c_volume_max = UAC2_DEF_MAX_DB;
        opts->c_volume_res = UAC2_DEF_RES_DB;

        opts->req_number = UAC2_DEF_REQ_NUM;
        opts->fb_max = FBACK_FAST_MAX;

        scnprintf(opts->function_name, sizeof(opts->function_name), "Source/Sink");
        scnprintf(opts->if_ctrl_name, sizeof(opts->if_ctrl_name), "Topology Control");
        scnprintf(opts->clksrc_in_name, sizeof(opts->clksrc_in_name), "Input Clock");
        scnprintf(opts->clksrc_out_name, sizeof(opts->clksrc_out_name), "Output Clock");

        scnprintf(opts->p_it_name, sizeof(opts->p_it_name), "USBD Out");
        scnprintf(opts->p_it_ch_name, sizeof(opts->p_it_ch_name), "Capture Channels");
        scnprintf(opts->p_ot_name, sizeof(opts->p_ot_name), "USBH In");
        scnprintf(opts->p_fu_vol_name, sizeof(opts->p_fu_vol_name), "Capture Volume");

        scnprintf(opts->c_it_name, sizeof(opts->c_it_name), "USBH Out");
        scnprintf(opts->c_it_ch_name, sizeof(opts->c_it_ch_name), "Playback Channels");
        scnprintf(opts->c_ot_name, sizeof(opts->c_ot_name), "USBD In");
        scnprintf(opts->c_fu_vol_name, sizeof(opts->c_fu_vol_name), "Playback Volume");

        opts->p_terminal_type = UAC2_DEF_P_TERM_TYPE;
        opts->c_terminal_type = UAC2_DEF_C_TERM_TYPE;

        return &opts->func_inst;
}

static void afunc_free(struct usb_function *f)
{
        struct g_audio *agdev;
        struct f_uac2_opts *opts;

        agdev = func_to_g_audio(f);
        opts = container_of(f->fi, struct f_uac2_opts, func_inst);
        kfree(agdev);
        mutex_lock(&opts->lock);
        --opts->refcnt;
        mutex_unlock(&opts->lock);
}

static void afunc_unbind(struct usb_configuration *c, struct usb_function *f)
{
        struct g_audio *agdev = func_to_g_audio(f);

        g_audio_cleanup(agdev);
        usb_free_all_descriptors(f);

        agdev->gadget = NULL;

        kfree(out_feature_unit_desc);
        out_feature_unit_desc = NULL;
        kfree(in_feature_unit_desc);
        in_feature_unit_desc = NULL;
}

static struct usb_function *afunc_alloc(struct usb_function_instance *fi)
{
        struct f_uac2   *uac2;
        struct f_uac2_opts *opts;

        uac2 = kzalloc_obj(*uac2);
        if (uac2 == NULL)
                return ERR_PTR(-ENOMEM);

        opts = container_of(fi, struct f_uac2_opts, func_inst);
        mutex_lock(&opts->lock);
        ++opts->refcnt;
        mutex_unlock(&opts->lock);

        uac2->g_audio.func.name = "uac2_func";
        uac2->g_audio.func.bind = afunc_bind;
        uac2->g_audio.func.unbind = afunc_unbind;
        uac2->g_audio.func.set_alt = afunc_set_alt;
        uac2->g_audio.func.get_alt = afunc_get_alt;
        uac2->g_audio.func.disable = afunc_disable;
        uac2->g_audio.func.suspend = afunc_suspend;
        uac2->g_audio.func.setup = afunc_setup;
        uac2->g_audio.func.free_func = afunc_free;

        return &uac2->g_audio.func;
}

DECLARE_USB_FUNCTION_INIT(uac2, afunc_alloc_inst, afunc_alloc);
MODULE_DESCRIPTION("USB Audio Class 2.0 Function");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Yadwinder Singh");
MODULE_AUTHOR("Jaswinder Singh");
MODULE_AUTHOR("Ruslan Bilovol");