root/drivers/usb/gadget/function/f_uac1_legacy.c
// SPDX-License-Identifier: GPL-2.0+
/*
 * f_audio.c -- USB Audio class function driver
  *
 * Copyright (C) 2008 Bryan Wu <cooloney@kernel.org>
 * Copyright (C) 2008 Analog Devices, Inc
 */

#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/atomic.h>

#include "u_uac1_legacy.h"

static int generic_set_cmd(struct usb_audio_control *con, u8 cmd, int value);
static int generic_get_cmd(struct usb_audio_control *con, u8 cmd);

/*
 * DESCRIPTORS ... most are static, but strings and full
 * configuration descriptors are built on demand.
 */

/*
 * We have two interfaces- AudioControl and AudioStreaming
 * TODO: only supcard playback currently
 */
#define F_AUDIO_AC_INTERFACE    0
#define F_AUDIO_AS_INTERFACE    1
#define F_AUDIO_NUM_INTERFACES  1

/* B.3.1  Standard AC Interface Descriptor */
static struct usb_interface_descriptor ac_interface_desc = {
        .bLength =              USB_DT_INTERFACE_SIZE,
        .bDescriptorType =      USB_DT_INTERFACE,
        .bNumEndpoints =        0,
        .bInterfaceClass =      USB_CLASS_AUDIO,
        .bInterfaceSubClass =   USB_SUBCLASS_AUDIOCONTROL,
};

/*
 * The number of AudioStreaming and MIDIStreaming interfaces
 * in the Audio Interface Collection
 */
DECLARE_UAC_AC_HEADER_DESCRIPTOR(1);

#define UAC_DT_AC_HEADER_LENGTH UAC_DT_AC_HEADER_SIZE(F_AUDIO_NUM_INTERFACES)
/* 1 input terminal, 1 output terminal and 1 feature unit */
#define UAC_DT_TOTAL_LENGTH (UAC_DT_AC_HEADER_LENGTH + UAC_DT_INPUT_TERMINAL_SIZE \
        + UAC_DT_OUTPUT_TERMINAL_SIZE + UAC_DT_FEATURE_UNIT_SIZE(0))
/* B.3.2  Class-Specific AC Interface Descriptor */
static struct uac1_ac_header_descriptor_1 ac_header_desc = {
        .bLength =              UAC_DT_AC_HEADER_LENGTH,
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubtype =   UAC_HEADER,
        .bcdADC =               cpu_to_le16(0x0100),
        .wTotalLength =         cpu_to_le16(UAC_DT_TOTAL_LENGTH),
        .bInCollection =        F_AUDIO_NUM_INTERFACES,
        .baInterfaceNr = {
        /* Interface number of the first AudioStream interface */
                [0] =           1,
        }
};

#define INPUT_TERMINAL_ID       1
static struct uac_input_terminal_descriptor input_terminal_desc = {
        .bLength =              UAC_DT_INPUT_TERMINAL_SIZE,
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubtype =   UAC_INPUT_TERMINAL,
        .bTerminalID =          INPUT_TERMINAL_ID,
        .wTerminalType =        UAC_TERMINAL_STREAMING,
        .bAssocTerminal =       0,
        .wChannelConfig =       0x3,
};

DECLARE_UAC_FEATURE_UNIT_DESCRIPTOR(0);

#define FEATURE_UNIT_ID         2
static struct uac_feature_unit_descriptor_0 feature_unit_desc = {
        .bLength                = UAC_DT_FEATURE_UNIT_SIZE(0),
        .bDescriptorType        = USB_DT_CS_INTERFACE,
        .bDescriptorSubtype     = UAC_FEATURE_UNIT,
        .bUnitID                = FEATURE_UNIT_ID,
        .bSourceID              = INPUT_TERMINAL_ID,
        .bControlSize           = 2,
        .bmaControls[0]         = (UAC_FU_MUTE | UAC_FU_VOLUME),
};

static struct usb_audio_control mute_control = {
        .list = LIST_HEAD_INIT(mute_control.list),
        .name = "Mute Control",
        .type = UAC_FU_MUTE,
        /* Todo: add real Mute control code */
        .set = generic_set_cmd,
        .get = generic_get_cmd,
};

static struct usb_audio_control volume_control = {
        .list = LIST_HEAD_INIT(volume_control.list),
        .name = "Volume Control",
        .type = UAC_FU_VOLUME,
        /* Todo: add real Volume control code */
        .set = generic_set_cmd,
        .get = generic_get_cmd,
};

static struct usb_audio_control_selector feature_unit = {
        .list = LIST_HEAD_INIT(feature_unit.list),
        .id = FEATURE_UNIT_ID,
        .name = "Mute & Volume Control",
        .type = UAC_FEATURE_UNIT,
        .desc = (struct usb_descriptor_header *)&feature_unit_desc,
};

#define OUTPUT_TERMINAL_ID      3
static struct uac1_output_terminal_descriptor output_terminal_desc = {
        .bLength                = UAC_DT_OUTPUT_TERMINAL_SIZE,
        .bDescriptorType        = USB_DT_CS_INTERFACE,
        .bDescriptorSubtype     = UAC_OUTPUT_TERMINAL,
        .bTerminalID            = OUTPUT_TERMINAL_ID,
        .wTerminalType          = UAC_OUTPUT_TERMINAL_SPEAKER,
        .bAssocTerminal         = FEATURE_UNIT_ID,
        .bSourceID              = FEATURE_UNIT_ID,
};

/* B.4.1  Standard AS Interface Descriptor */
static struct usb_interface_descriptor as_interface_alt_0_desc = {
        .bLength =              USB_DT_INTERFACE_SIZE,
        .bDescriptorType =      USB_DT_INTERFACE,
        .bAlternateSetting =    0,
        .bNumEndpoints =        0,
        .bInterfaceClass =      USB_CLASS_AUDIO,
        .bInterfaceSubClass =   USB_SUBCLASS_AUDIOSTREAMING,
};

static struct usb_interface_descriptor as_interface_alt_1_desc = {
        .bLength =              USB_DT_INTERFACE_SIZE,
        .bDescriptorType =      USB_DT_INTERFACE,
        .bAlternateSetting =    1,
        .bNumEndpoints =        1,
        .bInterfaceClass =      USB_CLASS_AUDIO,
        .bInterfaceSubClass =   USB_SUBCLASS_AUDIOSTREAMING,
};

/* B.4.2  Class-Specific AS Interface Descriptor */
static struct uac1_as_header_descriptor as_header_desc = {
        .bLength =              UAC_DT_AS_HEADER_SIZE,
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubtype =   UAC_AS_GENERAL,
        .bTerminalLink =        INPUT_TERMINAL_ID,
        .bDelay =               1,
        .wFormatTag =           UAC_FORMAT_TYPE_I_PCM,
};

DECLARE_UAC_FORMAT_TYPE_I_DISCRETE_DESC(1);

static struct uac_format_type_i_discrete_descriptor_1 as_type_i_desc = {
        .bLength =              UAC_FORMAT_TYPE_I_DISCRETE_DESC_SIZE(1),
        .bDescriptorType =      USB_DT_CS_INTERFACE,
        .bDescriptorSubtype =   UAC_FORMAT_TYPE,
        .bFormatType =          UAC_FORMAT_TYPE_I,
        .bSubframeSize =        2,
        .bBitResolution =       16,
        .bSamFreqType =         1,
};

/* Standard ISO OUT Endpoint Descriptor */
static struct usb_endpoint_descriptor as_out_ep_desc  = {
        .bLength =              USB_DT_ENDPOINT_AUDIO_SIZE,
        .bDescriptorType =      USB_DT_ENDPOINT,
        .bEndpointAddress =     USB_DIR_OUT,
        .bmAttributes =         USB_ENDPOINT_SYNC_ADAPTIVE
                                | USB_ENDPOINT_XFER_ISOC,
        .wMaxPacketSize =       cpu_to_le16(UAC1_OUT_EP_MAX_PACKET_SIZE),
        .bInterval =            4,
};

/* Class-specific AS ISO OUT Endpoint Descriptor */
static struct uac_iso_endpoint_descriptor as_iso_out_desc = {
        .bLength =              UAC_ISO_ENDPOINT_DESC_SIZE,
        .bDescriptorType =      USB_DT_CS_ENDPOINT,
        .bDescriptorSubtype =   UAC_EP_GENERAL,
        .bmAttributes =         1,
        .bLockDelayUnits =      1,
        .wLockDelay =           cpu_to_le16(1),
};

static struct usb_descriptor_header *f_audio_desc[] = {
        (struct usb_descriptor_header *)&ac_interface_desc,
        (struct usb_descriptor_header *)&ac_header_desc,

        (struct usb_descriptor_header *)&input_terminal_desc,
        (struct usb_descriptor_header *)&output_terminal_desc,
        (struct usb_descriptor_header *)&feature_unit_desc,

        (struct usb_descriptor_header *)&as_interface_alt_0_desc,
        (struct usb_descriptor_header *)&as_interface_alt_1_desc,
        (struct usb_descriptor_header *)&as_header_desc,

        (struct usb_descriptor_header *)&as_type_i_desc,

        (struct usb_descriptor_header *)&as_out_ep_desc,
        (struct usb_descriptor_header *)&as_iso_out_desc,
        NULL,
};

enum {
        STR_AC_IF,
        STR_INPUT_TERMINAL,
        STR_INPUT_TERMINAL_CH_NAMES,
        STR_FEAT_DESC_0,
        STR_OUTPUT_TERMINAL,
        STR_AS_IF_ALT0,
        STR_AS_IF_ALT1,
};

static struct usb_string strings_uac1[] = {
        [STR_AC_IF].s = "AC Interface",
        [STR_INPUT_TERMINAL].s = "Input terminal",
        [STR_INPUT_TERMINAL_CH_NAMES].s = "Channels",
        [STR_FEAT_DESC_0].s = "Volume control & mute",
        [STR_OUTPUT_TERMINAL].s = "Output terminal",
        [STR_AS_IF_ALT0].s = "AS Interface",
        [STR_AS_IF_ALT1].s = "AS Interface",
        { },
};

static struct usb_gadget_strings str_uac1 = {
        .language = 0x0409,     /* en-us */
        .strings = strings_uac1,
};

static struct usb_gadget_strings *uac1_strings[] = {
        &str_uac1,
        NULL,
};

/*
 * This function is an ALSA sound card following USB Audio Class Spec 1.0.
 */

/*-------------------------------------------------------------------------*/
struct f_audio_buf {
        u8 *buf;
        int actual;
        struct list_head list;
};

static struct f_audio_buf *f_audio_buffer_alloc(int buf_size)
{
        struct f_audio_buf *copy_buf;

        copy_buf = kzalloc_obj(*copy_buf, GFP_ATOMIC);
        if (!copy_buf)
                return ERR_PTR(-ENOMEM);

        copy_buf->buf = kzalloc(buf_size, GFP_ATOMIC);
        if (!copy_buf->buf) {
                kfree(copy_buf);
                return ERR_PTR(-ENOMEM);
        }

        return copy_buf;
}

static void f_audio_buffer_free(struct f_audio_buf *audio_buf)
{
        kfree(audio_buf->buf);
        kfree(audio_buf);
}
/*-------------------------------------------------------------------------*/

struct f_audio {
        struct gaudio                   card;

        u8 ac_intf, ac_alt;
        u8 as_intf, as_alt;

        /* endpoints handle full and/or high speeds */
        struct usb_ep                   *out_ep;

        spinlock_t                      lock;
        struct f_audio_buf *copy_buf;
        struct work_struct playback_work;
        struct list_head play_queue;

        /* Control Set command */
        struct list_head cs;
        u8 set_cmd;
        struct usb_audio_control *set_con;
};

static inline struct f_audio *func_to_audio(struct usb_function *f)
{
        return container_of(f, struct f_audio, card.func);
}

/*-------------------------------------------------------------------------*/

static void f_audio_playback_work(struct work_struct *data)
{
        struct f_audio *audio = container_of(data, struct f_audio,
                                        playback_work);
        struct f_audio_buf *play_buf;

        spin_lock_irq(&audio->lock);
        if (list_empty(&audio->play_queue)) {
                spin_unlock_irq(&audio->lock);
                return;
        }
        play_buf = list_first_entry(&audio->play_queue,
                        struct f_audio_buf, list);
        list_del(&play_buf->list);
        spin_unlock_irq(&audio->lock);

        u_audio_playback(&audio->card, play_buf->buf, play_buf->actual);
        f_audio_buffer_free(play_buf);
}

static int f_audio_out_ep_complete(struct usb_ep *ep, struct usb_request *req)
{
        struct f_audio *audio = req->context;
        struct usb_composite_dev *cdev = audio->card.func.config->cdev;
        struct f_audio_buf *copy_buf = audio->copy_buf;
        struct f_uac1_legacy_opts *opts;
        int audio_buf_size;
        int err;

        opts = container_of(audio->card.func.fi, struct f_uac1_legacy_opts,
                            func_inst);
        audio_buf_size = opts->audio_buf_size;

        if (!copy_buf)
                return -EINVAL;

        /* Copy buffer is full, add it to the play_queue */
        if (audio_buf_size - copy_buf->actual < req->actual) {
                spin_lock_irq(&audio->lock);
                list_add_tail(&copy_buf->list, &audio->play_queue);
                spin_unlock_irq(&audio->lock);
                schedule_work(&audio->playback_work);
                copy_buf = f_audio_buffer_alloc(audio_buf_size);
                if (IS_ERR(copy_buf))
                        return -ENOMEM;
        }

        memcpy(copy_buf->buf + copy_buf->actual, req->buf, req->actual);
        copy_buf->actual += req->actual;
        audio->copy_buf = copy_buf;

        err = usb_ep_queue(ep, req, GFP_ATOMIC);
        if (err)
                ERROR(cdev, "%s queue req: %d\n", ep->name, err);

        return 0;

}

static void f_audio_complete(struct usb_ep *ep, struct usb_request *req)
{
        struct f_audio *audio = req->context;
        struct usb_ep *out_ep = audio->out_ep;

        switch (req->status) {
        case 0:
                if (ep == out_ep) {
                        f_audio_out_ep_complete(ep, req);
                } else if (audio->set_con) {
                        struct usb_audio_control *con = audio->set_con;
                        u8 type = con->type;
                        u32 data;
                        bool valid_request = false;

                        switch (type) {
                        case UAC_FU_MUTE: {
                                u8 value;

                                if (req->actual == sizeof(value)) {
                                        memcpy(&value, req->buf, sizeof(value));
                                        data = value;
                                        valid_request = true;
                                }
                                break;
                        }
                        case UAC_FU_VOLUME: {
                                __le16 value;

                                if (req->actual == sizeof(value)) {
                                        memcpy(&value, req->buf, sizeof(value));
                                        data = le16_to_cpu(value);
                                        valid_request = true;
                                }
                                break;
                        }
                        }

                        if (valid_request)
                                con->set(con, audio->set_cmd, data);
                        else
                                usb_ep_set_halt(ep);

                        audio->set_con = NULL;
                }
                break;
        default:
                break;
        }
}

static int audio_set_intf_req(struct usb_function *f,
                const struct usb_ctrlrequest *ctrl)
{
        struct f_audio          *audio = func_to_audio(f);
        struct usb_composite_dev *cdev = f->config->cdev;
        struct usb_request      *req = cdev->req;
        u8                      id = ((le16_to_cpu(ctrl->wIndex) >> 8) & 0xFF);
        u16                     len = le16_to_cpu(ctrl->wLength);
        u16                     w_value = le16_to_cpu(ctrl->wValue);
        u8                      con_sel = (w_value >> 8) & 0xFF;
        u8                      cmd = (ctrl->bRequest & 0x0F);
        struct usb_audio_control_selector *cs;
        struct usb_audio_control *con;

        DBG(cdev, "bRequest 0x%x, w_value 0x%04x, len %d, entity %d\n",
                        ctrl->bRequest, w_value, len, id);

        list_for_each_entry(cs, &audio->cs, list) {
                if (cs->id == id) {
                        list_for_each_entry(con, &cs->control, list) {
                                if (con->type == con_sel) {
                                        audio->set_con = con;
                                        break;
                                }
                        }
                        break;
                }
        }

        audio->set_cmd = cmd;
        req->context = audio;
        req->complete = f_audio_complete;

        return len;
}

static int audio_get_intf_req(struct usb_function *f,
                const struct usb_ctrlrequest *ctrl)
{
        struct f_audio          *audio = func_to_audio(f);
        struct usb_composite_dev *cdev = f->config->cdev;
        struct usb_request      *req = cdev->req;
        int                     value = -EOPNOTSUPP;
        u8                      id = ((le16_to_cpu(ctrl->wIndex) >> 8) & 0xFF);
        u16                     len = le16_to_cpu(ctrl->wLength);
        u16                     w_value = le16_to_cpu(ctrl->wValue);
        u8                      con_sel = (w_value >> 8) & 0xFF;
        u8                      cmd = (ctrl->bRequest & 0x0F);
        struct usb_audio_control_selector *cs;
        struct usb_audio_control *con;

        DBG(cdev, "bRequest 0x%x, w_value 0x%04x, len %d, entity %d\n",
                        ctrl->bRequest, w_value, len, id);

        list_for_each_entry(cs, &audio->cs, list) {
                if (cs->id == id) {
                        list_for_each_entry(con, &cs->control, list) {
                                if (con->type == con_sel && con->get) {
                                        value = con->get(con, cmd);
                                        break;
                                }
                        }
                        break;
                }
        }

        req->context = audio;
        req->complete = f_audio_complete;
        len = min_t(size_t, sizeof(value), len);
        memcpy(req->buf, &value, len);

        return len;
}

static int audio_set_endpoint_req(struct usb_function *f,
                const struct usb_ctrlrequest *ctrl)
{
        struct usb_composite_dev *cdev = f->config->cdev;
        int                     value = -EOPNOTSUPP;
        u16                     ep = le16_to_cpu(ctrl->wIndex);
        u16                     len = le16_to_cpu(ctrl->wLength);
        u16                     w_value = le16_to_cpu(ctrl->wValue);

        DBG(cdev, "bRequest 0x%x, w_value 0x%04x, len %d, endpoint %d\n",
                        ctrl->bRequest, w_value, len, ep);

        switch (ctrl->bRequest) {
        case UAC_SET_CUR:
                value = len;
                break;

        case UAC_SET_MIN:
                break;

        case UAC_SET_MAX:
                break;

        case UAC_SET_RES:
                break;

        case UAC_SET_MEM:
                break;

        default:
                break;
        }

        return value;
}

static int audio_get_endpoint_req(struct usb_function *f,
                const struct usb_ctrlrequest *ctrl)
{
        struct usb_composite_dev *cdev = f->config->cdev;
        int value = -EOPNOTSUPP;
        u8 ep = ((le16_to_cpu(ctrl->wIndex) >> 8) & 0xFF);
        u16 len = le16_to_cpu(ctrl->wLength);
        u16 w_value = le16_to_cpu(ctrl->wValue);

        DBG(cdev, "bRequest 0x%x, w_value 0x%04x, len %d, endpoint %d\n",
                        ctrl->bRequest, w_value, len, ep);

        switch (ctrl->bRequest) {
        case UAC_GET_CUR:
        case UAC_GET_MIN:
        case UAC_GET_MAX:
        case UAC_GET_RES:
                value = len;
                break;
        case UAC_GET_MEM:
                break;
        default:
                break;
        }

        return value;
}

static int
f_audio_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
{
        struct usb_composite_dev *cdev = f->config->cdev;
        struct usb_request      *req = cdev->req;
        int                     value = -EOPNOTSUPP;
        u16                     w_index = le16_to_cpu(ctrl->wIndex);
        u16                     w_value = le16_to_cpu(ctrl->wValue);
        u16                     w_length = le16_to_cpu(ctrl->wLength);

        /* composite driver infrastructure handles everything; interface
         * activation uses set_alt().
         */
        switch (ctrl->bRequestType) {
        case USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE:
                value = audio_set_intf_req(f, ctrl);
                break;

        case USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE:
                value = audio_get_intf_req(f, ctrl);
                break;

        case USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_ENDPOINT:
                value = audio_set_endpoint_req(f, ctrl);
                break;

        case USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_ENDPOINT:
                value = audio_get_endpoint_req(f, ctrl);
                break;

        default:
                ERROR(cdev, "invalid control req%02x.%02x v%04x i%04x l%d\n",
                        ctrl->bRequestType, ctrl->bRequest,
                        w_value, w_index, w_length);
        }

        /* respond with data transfer or status phase? */
        if (value >= 0) {
                DBG(cdev, "audio req%02x.%02x v%04x i%04x l%d\n",
                        ctrl->bRequestType, ctrl->bRequest,
                        w_value, w_index, w_length);
                req->zero = 0;
                req->length = value;
                value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
                if (value < 0)
                        ERROR(cdev, "audio response on err %d\n", value);
        }

        /* device either stalls (value < 0) or reports success */
        return value;
}

static int f_audio_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
{
        struct f_audio          *audio = func_to_audio(f);
        struct usb_composite_dev *cdev = f->config->cdev;
        struct usb_ep *out_ep = audio->out_ep;
        struct usb_request *req;
        struct f_uac1_legacy_opts *opts;
        int req_buf_size, req_count, audio_buf_size;
        int i = 0, err = 0;

        DBG(cdev, "intf %d, alt %d\n", intf, alt);

        opts = container_of(f->fi, struct f_uac1_legacy_opts, func_inst);
        req_buf_size = opts->req_buf_size;
        req_count = opts->req_count;
        audio_buf_size = opts->audio_buf_size;

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

        if (intf == audio->ac_intf) {
                /* Control I/f has only 1 AltSetting - 0 */
                if (alt) {
                        ERROR(cdev, "%s:%d Error!\n", __func__, __LINE__);
                        return -EINVAL;
                }
                return 0;
        } else if (intf == audio->as_intf) {
                if (alt == 1) {
                        err = config_ep_by_speed(cdev->gadget, f, out_ep);
                        if (err)
                                return err;

                        usb_ep_enable(out_ep);
                        audio->copy_buf = f_audio_buffer_alloc(audio_buf_size);
                        if (IS_ERR(audio->copy_buf))
                                return -ENOMEM;

                        /*
                         * allocate a bunch of read buffers
                         * and queue them all at once.
                         */
                        for (i = 0; i < req_count && err == 0; i++) {
                                req = usb_ep_alloc_request(out_ep, GFP_ATOMIC);
                                if (req) {
                                        req->buf = kzalloc(req_buf_size,
                                                        GFP_ATOMIC);
                                        if (req->buf) {
                                                req->length = req_buf_size;
                                                req->context = audio;
                                                req->complete =
                                                        f_audio_complete;
                                                err = usb_ep_queue(out_ep,
                                                        req, GFP_ATOMIC);
                                                if (err)
                                                        ERROR(cdev,
                                                        "%s queue req: %d\n",
                                                        out_ep->name, err);
                                        } else
                                                err = -ENOMEM;
                                } else
                                        err = -ENOMEM;
                        }

                } else {
                        struct f_audio_buf *copy_buf = audio->copy_buf;
                        if (copy_buf) {
                                list_add_tail(&copy_buf->list,
                                                &audio->play_queue);
                                schedule_work(&audio->playback_work);
                        }
                }
                audio->as_alt = alt;
        }

        return err;
}

static int f_audio_get_alt(struct usb_function *f, unsigned intf)
{
        struct f_audio          *audio = func_to_audio(f);
        struct usb_composite_dev *cdev = f->config->cdev;

        if (intf == audio->ac_intf)
                return audio->ac_alt;
        else if (intf == audio->as_intf)
                return audio->as_alt;
        else
                ERROR(cdev, "%s:%d Invalid Interface %d!\n",
                      __func__, __LINE__, intf);

        return -EINVAL;
}

static void f_audio_disable(struct usb_function *f)
{
        return;
}

/*-------------------------------------------------------------------------*/

static void f_audio_build_desc(struct f_audio *audio)
{
        struct gaudio *card = &audio->card;
        u8 *sam_freq;
        int rate;

        /* Set channel numbers */
        input_terminal_desc.bNrChannels = u_audio_get_playback_channels(card);
        as_type_i_desc.bNrChannels = u_audio_get_playback_channels(card);

        /* Set sample rates */
        rate = u_audio_get_playback_rate(card);
        sam_freq = as_type_i_desc.tSamFreq[0];
        memcpy(sam_freq, &rate, 3);

        /* Todo: Set Sample bits and other parameters */

        return;
}

/* audio function driver setup/binding */
static int
f_audio_bind(struct usb_configuration *c, struct usb_function *f)
{
        struct usb_composite_dev *cdev = c->cdev;
        struct f_audio          *audio = func_to_audio(f);
        struct usb_string       *us;
        int                     status;
        struct usb_ep           *ep = NULL;
        struct f_uac1_legacy_opts       *audio_opts;

        audio_opts = container_of(f->fi, struct f_uac1_legacy_opts, func_inst);
        audio->card.gadget = c->cdev->gadget;
        /* set up ASLA audio devices */
        if (!audio_opts->bound) {
                status = gaudio_setup(&audio->card);
                if (status < 0)
                        return status;
                audio_opts->bound = true;
        }
        us = usb_gstrings_attach(cdev, uac1_strings, ARRAY_SIZE(strings_uac1));
        if (IS_ERR(us))
                return PTR_ERR(us);
        ac_interface_desc.iInterface = us[STR_AC_IF].id;
        input_terminal_desc.iTerminal = us[STR_INPUT_TERMINAL].id;
        input_terminal_desc.iChannelNames = us[STR_INPUT_TERMINAL_CH_NAMES].id;
        feature_unit_desc.iFeature = us[STR_FEAT_DESC_0].id;
        output_terminal_desc.iTerminal = us[STR_OUTPUT_TERMINAL].id;
        as_interface_alt_0_desc.iInterface = us[STR_AS_IF_ALT0].id;
        as_interface_alt_1_desc.iInterface = us[STR_AS_IF_ALT1].id;


        f_audio_build_desc(audio);

        /* allocate instance-specific interface IDs, and patch descriptors */
        status = usb_interface_id(c, f);
        if (status < 0)
                goto fail;
        ac_interface_desc.bInterfaceNumber = status;
        audio->ac_intf = status;
        audio->ac_alt = 0;

        status = usb_interface_id(c, f);
        if (status < 0)
                goto fail;
        as_interface_alt_0_desc.bInterfaceNumber = status;
        as_interface_alt_1_desc.bInterfaceNumber = status;
        audio->as_intf = status;
        audio->as_alt = 0;

        status = -ENODEV;

        /* allocate instance-specific endpoints */
        ep = usb_ep_autoconfig(cdev->gadget, &as_out_ep_desc);
        if (!ep)
                goto fail;
        audio->out_ep = ep;
        audio->out_ep->desc = &as_out_ep_desc;

        /* copy descriptors, and track endpoint copies */
        status = usb_assign_descriptors(f, f_audio_desc, f_audio_desc, NULL,
                                        NULL);
        if (status)
                goto fail;
        return 0;

fail:
        gaudio_cleanup(&audio->card);
        return status;
}

/*-------------------------------------------------------------------------*/

static int generic_set_cmd(struct usb_audio_control *con, u8 cmd, int value)
{
        con->data[cmd] = value;

        return 0;
}

static int generic_get_cmd(struct usb_audio_control *con, u8 cmd)
{
        return con->data[cmd];
}

/* Todo: add more control selecotor dynamically */
static int control_selector_init(struct f_audio *audio)
{
        INIT_LIST_HEAD(&audio->cs);
        list_add(&feature_unit.list, &audio->cs);

        INIT_LIST_HEAD(&feature_unit.control);
        list_add(&mute_control.list, &feature_unit.control);
        list_add(&volume_control.list, &feature_unit.control);

        volume_control.data[UAC__CUR] = 0xffc0;
        volume_control.data[UAC__MIN] = 0xe3a0;
        volume_control.data[UAC__MAX] = 0xfff0;
        volume_control.data[UAC__RES] = 0x0030;

        return 0;
}

static inline
struct f_uac1_legacy_opts *to_f_uac1_opts(struct config_item *item)
{
        return container_of(to_config_group(item), struct f_uac1_legacy_opts,
                            func_inst.group);
}

static void f_uac1_attr_release(struct config_item *item)
{
        struct f_uac1_legacy_opts *opts = to_f_uac1_opts(item);

        usb_put_function_instance(&opts->func_inst);
}

static const struct configfs_item_operations f_uac1_item_ops = {
        .release        = f_uac1_attr_release,
};

#define UAC1_INT_ATTRIBUTE(name)                                        \
static ssize_t f_uac1_opts_##name##_show(struct config_item *item,      \
                                         char *page)                    \
{                                                                       \
        struct f_uac1_legacy_opts *opts = to_f_uac1_opts(item);         \
        int result;                                                     \
                                                                        \
        mutex_lock(&opts->lock);                                        \
        result = sprintf(page, "%u\n", opts->name);                     \
        mutex_unlock(&opts->lock);                                      \
                                                                        \
        return result;                                                  \
}                                                                       \
                                                                        \
static ssize_t f_uac1_opts_##name##_store(struct config_item *item,             \
                                          const char *page, size_t len) \
{                                                                       \
        struct f_uac1_legacy_opts *opts = to_f_uac1_opts(item);         \
        int ret;                                                        \
        u32 num;                                                        \
                                                                        \
        mutex_lock(&opts->lock);                                        \
        if (opts->refcnt) {                                             \
                ret = -EBUSY;                                           \
                goto end;                                               \
        }                                                               \
                                                                        \
        ret = kstrtou32(page, 0, &num);                                 \
        if (ret)                                                        \
                goto end;                                               \
                                                                        \
        opts->name = num;                                               \
        ret = len;                                                      \
                                                                        \
end:                                                                    \
        mutex_unlock(&opts->lock);                                      \
        return ret;                                                     \
}                                                                       \
                                                                        \
CONFIGFS_ATTR(f_uac1_opts_, name)

UAC1_INT_ATTRIBUTE(req_buf_size);
UAC1_INT_ATTRIBUTE(req_count);
UAC1_INT_ATTRIBUTE(audio_buf_size);

#define UAC1_STR_ATTRIBUTE(name)                                        \
static ssize_t f_uac1_opts_##name##_show(struct config_item *item,      \
                                         char *page)                    \
{                                                                       \
        struct f_uac1_legacy_opts *opts = to_f_uac1_opts(item);         \
        int result;                                                     \
                                                                        \
        mutex_lock(&opts->lock);                                        \
        result = sprintf(page, "%s\n", opts->name);                     \
        mutex_unlock(&opts->lock);                                      \
                                                                        \
        return result;                                                  \
}                                                                       \
                                                                        \
static ssize_t f_uac1_opts_##name##_store(struct config_item *item,     \
                                          const char *page, size_t len) \
{                                                                       \
        struct f_uac1_legacy_opts *opts = to_f_uac1_opts(item);         \
        int ret = -EBUSY;                                               \
        char *tmp;                                                      \
                                                                        \
        mutex_lock(&opts->lock);                                        \
        if (opts->refcnt)                                               \
                goto end;                                               \
                                                                        \
        tmp = kstrndup(page, len, GFP_KERNEL);                          \
        if (tmp) {                                                      \
                ret = -ENOMEM;                                          \
                goto end;                                               \
        }                                                               \
        if (opts->name##_alloc)                                         \
                kfree(opts->name);                                      \
        opts->name##_alloc = true;                                      \
        opts->name = tmp;                                               \
        ret = len;                                                      \
                                                                        \
end:                                                                    \
        mutex_unlock(&opts->lock);                                      \
        return ret;                                                     \
}                                                                       \
                                                                        \
CONFIGFS_ATTR(f_uac1_opts_, name)

UAC1_STR_ATTRIBUTE(fn_play);
UAC1_STR_ATTRIBUTE(fn_cap);
UAC1_STR_ATTRIBUTE(fn_cntl);

static struct configfs_attribute *f_uac1_attrs[] = {
        &f_uac1_opts_attr_req_buf_size,
        &f_uac1_opts_attr_req_count,
        &f_uac1_opts_attr_audio_buf_size,
        &f_uac1_opts_attr_fn_play,
        &f_uac1_opts_attr_fn_cap,
        &f_uac1_opts_attr_fn_cntl,
        NULL,
};

static const struct config_item_type f_uac1_func_type = {
        .ct_item_ops    = &f_uac1_item_ops,
        .ct_attrs       = f_uac1_attrs,
        .ct_owner       = THIS_MODULE,
};

static void f_audio_free_inst(struct usb_function_instance *f)
{
        struct f_uac1_legacy_opts *opts;

        opts = container_of(f, struct f_uac1_legacy_opts, func_inst);
        if (opts->fn_play_alloc)
                kfree(opts->fn_play);
        if (opts->fn_cap_alloc)
                kfree(opts->fn_cap);
        if (opts->fn_cntl_alloc)
                kfree(opts->fn_cntl);
        kfree(opts);
}

static struct usb_function_instance *f_audio_alloc_inst(void)
{
        struct f_uac1_legacy_opts *opts;

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

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

        config_group_init_type_name(&opts->func_inst.group, "",
                                    &f_uac1_func_type);

        opts->req_buf_size = UAC1_OUT_EP_MAX_PACKET_SIZE;
        opts->req_count = UAC1_REQ_COUNT;
        opts->audio_buf_size = UAC1_AUDIO_BUF_SIZE;
        opts->fn_play = FILE_PCM_PLAYBACK;
        opts->fn_cap = FILE_PCM_CAPTURE;
        opts->fn_cntl = FILE_CONTROL;
        return &opts->func_inst;
}

static void f_audio_free(struct usb_function *f)
{
        struct f_audio *audio = func_to_audio(f);
        struct f_uac1_legacy_opts *opts;

        gaudio_cleanup(&audio->card);
        opts = container_of(f->fi, struct f_uac1_legacy_opts, func_inst);
        kfree(audio);
        mutex_lock(&opts->lock);
        --opts->refcnt;
        mutex_unlock(&opts->lock);
}

static void f_audio_unbind(struct usb_configuration *c, struct usb_function *f)
{
        usb_free_all_descriptors(f);
}

static struct usb_function *f_audio_alloc(struct usb_function_instance *fi)
{
        struct f_audio *audio;
        struct f_uac1_legacy_opts *opts;

        /* allocate and initialize one new instance */
        audio = kzalloc_obj(*audio);
        if (!audio)
                return ERR_PTR(-ENOMEM);

        audio->card.func.name = "g_audio";

        opts = container_of(fi, struct f_uac1_legacy_opts, func_inst);
        mutex_lock(&opts->lock);
        ++opts->refcnt;
        mutex_unlock(&opts->lock);
        INIT_LIST_HEAD(&audio->play_queue);
        spin_lock_init(&audio->lock);

        audio->card.func.bind = f_audio_bind;
        audio->card.func.unbind = f_audio_unbind;
        audio->card.func.set_alt = f_audio_set_alt;
        audio->card.func.get_alt = f_audio_get_alt;
        audio->card.func.setup = f_audio_setup;
        audio->card.func.disable = f_audio_disable;
        audio->card.func.free_func = f_audio_free;

        control_selector_init(audio);

        INIT_WORK(&audio->playback_work, f_audio_playback_work);

        return &audio->card.func;
}

DECLARE_USB_FUNCTION_INIT(uac1_legacy, f_audio_alloc_inst, f_audio_alloc);
MODULE_DESCRIPTION("USB Audio class function driver");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Bryan Wu");