// SPDX-License-Identifier: GPL-2.0+
/*
 *      uvc_gadget.c  --  USB Video Class Gadget driver
 *
 *      Copyright (C) 2009-2010
 *          Laurent Pinchart (laurent.pinchart@ideasonboard.com)
 */

#include <linux/device.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/string.h>
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>
#include <linux/usb/g_uvc.h>
#include <linux/usb/video.h>
#include <linux/vmalloc.h>
#include <linux/wait.h>

#include <media/v4l2-dev.h>
#include <media/v4l2-event.h>

#include "uvc.h"
#include "uvc_configfs.h"
#include "uvc_v4l2.h"
#include "uvc_video.h"

unsigned int uvc_gadget_trace_param;
module_param_named(trace, uvc_gadget_trace_param, uint, 0644);
MODULE_PARM_DESC(trace, "Trace level bitmask");

/* --------------------------------------------------------------------------
 * Function descriptors
 */

/* string IDs are assigned dynamically */

static struct usb_string uvc_en_us_strings[] = {
        /* [UVC_STRING_CONTROL_IDX].s = DYNAMIC, */
        [UVC_STRING_STREAMING_IDX].s = "Video Streaming",
        {  }
};

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

static struct usb_gadget_strings *uvc_function_strings[] = {
        &uvc_stringtab,
        NULL,
};

#define UVC_INTF_VIDEO_CONTROL                  0
#define UVC_INTF_VIDEO_STREAMING                1

#define UVC_STATUS_MAX_PACKET_SIZE              16      /* 16 bytes status */

static struct usb_interface_assoc_descriptor uvc_iad = {
        .bLength                = sizeof(uvc_iad),
        .bDescriptorType        = USB_DT_INTERFACE_ASSOCIATION,
        .bFirstInterface        = 0,
        .bInterfaceCount        = 2,
        .bFunctionClass         = USB_CLASS_VIDEO,
        .bFunctionSubClass      = UVC_SC_VIDEO_INTERFACE_COLLECTION,
        .bFunctionProtocol      = 0x00,
        .iFunction              = 0,
};

static struct usb_interface_descriptor uvc_control_intf = {
        .bLength                = USB_DT_INTERFACE_SIZE,
        .bDescriptorType        = USB_DT_INTERFACE,
        .bInterfaceNumber       = UVC_INTF_VIDEO_CONTROL,
        .bAlternateSetting      = 0,
        .bNumEndpoints          = 0,
        .bInterfaceClass        = USB_CLASS_VIDEO,
        .bInterfaceSubClass     = UVC_SC_VIDEOCONTROL,
        .bInterfaceProtocol     = 0x00,
        .iInterface             = 0,
};

static struct usb_endpoint_descriptor uvc_interrupt_ep = {
        .bLength                = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType        = USB_DT_ENDPOINT,
        .bEndpointAddress       = USB_DIR_IN,
        .bmAttributes           = USB_ENDPOINT_XFER_INT,
        .wMaxPacketSize         = cpu_to_le16(UVC_STATUS_MAX_PACKET_SIZE),
        .bInterval              = 8,
};

static struct usb_ss_ep_comp_descriptor uvc_ss_interrupt_comp = {
        .bLength                = sizeof(uvc_ss_interrupt_comp),
        .bDescriptorType        = USB_DT_SS_ENDPOINT_COMP,
        /* The following 3 values can be tweaked if necessary. */
        .bMaxBurst              = 0,
        .bmAttributes           = 0,
        .wBytesPerInterval      = cpu_to_le16(UVC_STATUS_MAX_PACKET_SIZE),
};

static struct uvc_control_endpoint_descriptor uvc_interrupt_cs_ep = {
        .bLength                = UVC_DT_CONTROL_ENDPOINT_SIZE,
        .bDescriptorType        = USB_DT_CS_ENDPOINT,
        .bDescriptorSubType     = UVC_EP_INTERRUPT,
        .wMaxTransferSize       = cpu_to_le16(UVC_STATUS_MAX_PACKET_SIZE),
};

static struct usb_interface_descriptor uvc_streaming_intf_alt0 = {
        .bLength                = USB_DT_INTERFACE_SIZE,
        .bDescriptorType        = USB_DT_INTERFACE,
        .bInterfaceNumber       = UVC_INTF_VIDEO_STREAMING,
        .bAlternateSetting      = 0,
        .bNumEndpoints          = 0,
        .bInterfaceClass        = USB_CLASS_VIDEO,
        .bInterfaceSubClass     = UVC_SC_VIDEOSTREAMING,
        .bInterfaceProtocol     = 0x00,
        .iInterface             = 0,
};

static struct usb_interface_descriptor uvc_streaming_intf_alt1 = {
        .bLength                = USB_DT_INTERFACE_SIZE,
        .bDescriptorType        = USB_DT_INTERFACE,
        .bInterfaceNumber       = UVC_INTF_VIDEO_STREAMING,
        .bAlternateSetting      = 1,
        .bNumEndpoints          = 1,
        .bInterfaceClass        = USB_CLASS_VIDEO,
        .bInterfaceSubClass     = UVC_SC_VIDEOSTREAMING,
        .bInterfaceProtocol     = 0x00,
        .iInterface             = 0,
};

static struct usb_endpoint_descriptor uvc_fs_streaming_ep = {
        .bLength                = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType        = USB_DT_ENDPOINT,
        .bEndpointAddress       = USB_DIR_IN,
        .bmAttributes           = USB_ENDPOINT_SYNC_ASYNC
                                | USB_ENDPOINT_XFER_ISOC,
        /*
         * The wMaxPacketSize and bInterval values will be initialized from
         * module parameters.
         */
};

static struct usb_endpoint_descriptor uvc_hs_streaming_ep = {
        .bLength                = USB_DT_ENDPOINT_SIZE,
        .bDescriptorType        = USB_DT_ENDPOINT,
        .bEndpointAddress       = USB_DIR_IN,
        .bmAttributes           = USB_ENDPOINT_SYNC_ASYNC
                                | USB_ENDPOINT_XFER_ISOC,
        /*
         * The wMaxPacketSize and bInterval values will be initialized from
         * module parameters.
         */
};

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

        .bEndpointAddress       = USB_DIR_IN,
        .bmAttributes           = USB_ENDPOINT_SYNC_ASYNC
                                | USB_ENDPOINT_XFER_ISOC,
        /*
         * The wMaxPacketSize and bInterval values will be initialized from
         * module parameters.
         */
};

static struct usb_ss_ep_comp_descriptor uvc_ss_streaming_comp = {
        .bLength                = sizeof(uvc_ss_streaming_comp),
        .bDescriptorType        = USB_DT_SS_ENDPOINT_COMP,
        /*
         * The bMaxBurst, bmAttributes and wBytesPerInterval values will be
         * initialized from module parameters.
         */
};

static const struct usb_descriptor_header * const uvc_fs_streaming[] = {
        (struct usb_descriptor_header *) &uvc_streaming_intf_alt1,
        (struct usb_descriptor_header *) &uvc_fs_streaming_ep,
        NULL,
};

static const struct usb_descriptor_header * const uvc_hs_streaming[] = {
        (struct usb_descriptor_header *) &uvc_streaming_intf_alt1,
        (struct usb_descriptor_header *) &uvc_hs_streaming_ep,
        NULL,
};

static const struct usb_descriptor_header * const uvc_ss_streaming[] = {
        (struct usb_descriptor_header *) &uvc_streaming_intf_alt1,
        (struct usb_descriptor_header *) &uvc_ss_streaming_ep,
        (struct usb_descriptor_header *) &uvc_ss_streaming_comp,
        NULL,
};

/* --------------------------------------------------------------------------
 * Control requests
 */

static void
uvc_function_ep0_complete(struct usb_ep *ep, struct usb_request *req)
{
        struct uvc_device *uvc = req->context;
        struct v4l2_event v4l2_event;
        struct uvc_event *uvc_event = (void *)&v4l2_event.u.data;

        if (uvc->event_setup_out) {
                uvc->event_setup_out = 0;

                memset(&v4l2_event, 0, sizeof(v4l2_event));
                v4l2_event.type = UVC_EVENT_DATA;
                uvc_event->data.length = min_t(unsigned int, req->actual,
                        sizeof(uvc_event->data.data));
                memcpy(&uvc_event->data.data, req->buf, uvc_event->data.length);
                v4l2_event_queue(&uvc->vdev, &v4l2_event);
        }
}

static int
uvc_function_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
{
        struct uvc_device *uvc = to_uvc(f);
        struct v4l2_event v4l2_event;
        struct uvc_event *uvc_event = (void *)&v4l2_event.u.data;
        unsigned int interface = le16_to_cpu(ctrl->wIndex) & 0xff;
        struct usb_ctrlrequest *mctrl;

        if ((ctrl->bRequestType & USB_TYPE_MASK) != USB_TYPE_CLASS) {
                uvcg_info(f, "invalid request type\n");
                return -EINVAL;
        }

        /* Stall too big requests. */
        if (le16_to_cpu(ctrl->wLength) > UVC_MAX_REQUEST_SIZE)
                return -EINVAL;

        /*
         * Tell the complete callback to generate an event for the next request
         * that will be enqueued by UVCIOC_SEND_RESPONSE.
         */
        uvc->event_setup_out = !(ctrl->bRequestType & USB_DIR_IN);
        uvc->event_length = le16_to_cpu(ctrl->wLength);

        memset(&v4l2_event, 0, sizeof(v4l2_event));
        v4l2_event.type = UVC_EVENT_SETUP;
        memcpy(&uvc_event->req, ctrl, sizeof(uvc_event->req));

        /* check for the interface number, fixup the interface number in
         * the ctrl request so the userspace doesn't have to bother with
         * offset and configfs parsing
         */
        mctrl = &uvc_event->req;
        mctrl->wIndex &= ~cpu_to_le16(0xff);
        if (interface == uvc->streaming_intf)
                mctrl->wIndex = cpu_to_le16(UVC_STRING_STREAMING_IDX);

        v4l2_event_queue(&uvc->vdev, &v4l2_event);

        return 0;
}

void uvc_function_setup_continue(struct uvc_device *uvc, int disable_ep)
{
        struct usb_composite_dev *cdev = uvc->func.config->cdev;

        if (disable_ep && uvc->video.ep)
                usb_ep_disable(uvc->video.ep);

        usb_composite_setup_continue(cdev);
}

static int
uvc_function_get_alt(struct usb_function *f, unsigned interface)
{
        struct uvc_device *uvc = to_uvc(f);

        uvcg_info(f, "%s(%u)\n", __func__, interface);

        if (interface == uvc->control_intf)
                return 0;
        else if (interface != uvc->streaming_intf)
                return -EINVAL;
        else
                return uvc->video.ep->enabled ? 1 : 0;
}

static int
uvc_function_set_alt(struct usb_function *f, unsigned interface, unsigned alt)
{
        struct uvc_device *uvc = to_uvc(f);
        struct usb_composite_dev *cdev = f->config->cdev;
        struct v4l2_event v4l2_event;
        struct uvc_event *uvc_event = (void *)&v4l2_event.u.data;
        int ret;

        uvcg_info(f, "%s(%u, %u)\n", __func__, interface, alt);

        if (interface == uvc->control_intf) {
                if (alt)
                        return -EINVAL;

                if (uvc->enable_interrupt_ep) {
                        uvcg_info(f, "reset UVC interrupt endpoint\n");
                        usb_ep_disable(uvc->interrupt_ep);

                        if (!uvc->interrupt_ep->desc)
                                if (config_ep_by_speed(cdev->gadget, f,
                                                       uvc->interrupt_ep))
                                        return -EINVAL;

                        usb_ep_enable(uvc->interrupt_ep);
                }

                if (uvc->state == UVC_STATE_DISCONNECTED) {
                        memset(&v4l2_event, 0, sizeof(v4l2_event));
                        v4l2_event.type = UVC_EVENT_CONNECT;
                        uvc_event->speed = cdev->gadget->speed;
                        v4l2_event_queue(&uvc->vdev, &v4l2_event);

                        uvc->state = UVC_STATE_CONNECTED;
                }

                return 0;
        }

        if (interface != uvc->streaming_intf)
                return -EINVAL;

        /* TODO
        if (usb_endpoint_xfer_bulk(&uvc->desc.vs_ep))
                return alt ? -EINVAL : 0;
        */

        switch (alt) {
        case 0:
                if (uvc->state != UVC_STATE_STREAMING)
                        return 0;

                memset(&v4l2_event, 0, sizeof(v4l2_event));
                v4l2_event.type = UVC_EVENT_STREAMOFF;
                v4l2_event_queue(&uvc->vdev, &v4l2_event);

                return USB_GADGET_DELAYED_STATUS;

        case 1:
                if (uvc->state != UVC_STATE_CONNECTED)
                        return 0;

                if (!uvc->video.ep)
                        return -EINVAL;

                uvcg_info(f, "reset UVC\n");
                usb_ep_disable(uvc->video.ep);

                ret = config_ep_by_speed(f->config->cdev->gadget,
                                &(uvc->func), uvc->video.ep);
                if (ret)
                        return ret;
                usb_ep_enable(uvc->video.ep);

                uvc->video.max_req_size = uvc->video.ep->maxpacket
                        * max_t(unsigned int, uvc->video.ep->maxburst, 1)
                        * (uvc->video.ep->mult);

                memset(&v4l2_event, 0, sizeof(v4l2_event));
                v4l2_event.type = UVC_EVENT_STREAMON;
                v4l2_event_queue(&uvc->vdev, &v4l2_event);
                return USB_GADGET_DELAYED_STATUS;

        default:
                return -EINVAL;
        }
}

static void
uvc_function_disable(struct usb_function *f)
{
        struct uvc_device *uvc = to_uvc(f);
        struct v4l2_event v4l2_event;

        uvcg_info(f, "%s()\n", __func__);

        memset(&v4l2_event, 0, sizeof(v4l2_event));
        v4l2_event.type = UVC_EVENT_DISCONNECT;
        v4l2_event_queue(&uvc->vdev, &v4l2_event);

        uvc->state = UVC_STATE_DISCONNECTED;

        usb_ep_disable(uvc->video.ep);
        if (uvc->enable_interrupt_ep)
                usb_ep_disable(uvc->interrupt_ep);
}

/* --------------------------------------------------------------------------
 * Connection / disconnection
 */

void
uvc_function_connect(struct uvc_device *uvc)
{
        int ret;

        if ((ret = usb_function_activate(&uvc->func)) < 0)
                uvcg_info(&uvc->func, "UVC connect failed with %d\n", ret);
}

void
uvc_function_disconnect(struct uvc_device *uvc)
{
        int ret;

        guard(mutex)(&uvc->lock);
        if (uvc->func_unbound) {
                dev_dbg(&uvc->vdev.dev, "skipping function deactivate (unbound)\n");
                return;
        }

        if ((ret = usb_function_deactivate(&uvc->func)) < 0)
                uvcg_info(&uvc->func, "UVC disconnect failed with %d\n", ret);
}

/* --------------------------------------------------------------------------
 * USB probe and disconnect
 */

static ssize_t function_name_show(struct device *dev,
                                  struct device_attribute *attr, char *buf)
{
        struct uvc_device *uvc = dev_get_drvdata(dev);

        return sprintf(buf, "%s\n", uvc->func.fi->group.cg_item.ci_name);
}

static DEVICE_ATTR_RO(function_name);

static void uvc_vdev_release(struct video_device *vdev)
{
        struct uvc_device *uvc = video_get_drvdata(vdev);

        /* Signal uvc_function_unbind() that the video device has been released */
        if (uvc->vdev_release_done)
                complete(uvc->vdev_release_done);
}

static int
uvc_register_video(struct uvc_device *uvc)
{
        struct usb_composite_dev *cdev = uvc->func.config->cdev;
        int ret;

        /* TODO reference counting. */
        memset(&uvc->vdev, 0, sizeof(uvc->vdev));
        uvc->vdev.v4l2_dev = &uvc->v4l2_dev;
        uvc->vdev.v4l2_dev->dev = &cdev->gadget->dev;
        uvc->vdev.fops = &uvc_v4l2_fops;
        uvc->vdev.ioctl_ops = &uvc_v4l2_ioctl_ops;
        uvc->vdev.release = uvc_vdev_release;
        uvc->vdev.vfl_dir = VFL_DIR_TX;
        uvc->vdev.lock = &uvc->video.mutex;
        uvc->vdev.device_caps = V4L2_CAP_VIDEO_OUTPUT | V4L2_CAP_STREAMING;
        strscpy(uvc->vdev.name, cdev->gadget->name, sizeof(uvc->vdev.name));

        video_set_drvdata(&uvc->vdev, uvc);

        ret = video_register_device(&uvc->vdev, VFL_TYPE_VIDEO, -1);
        if (ret < 0)
                return ret;

        ret = device_create_file(&uvc->vdev.dev, &dev_attr_function_name);
        if (ret < 0) {
                video_unregister_device(&uvc->vdev);
                return ret;
        }

        return 0;
}

#define UVC_COPY_DESCRIPTOR(mem, dst, desc) \
        do { \
                memcpy(mem, desc, (desc)->bLength); \
                *(dst)++ = mem; \
                mem += (desc)->bLength; \
        } while (0)

#define UVC_COPY_DESCRIPTORS(mem, dst, src) \
        do { \
                const struct usb_descriptor_header * const *__src; \
                for (__src = src; *__src; ++__src) { \
                        memcpy(mem, *__src, (*__src)->bLength); \
                        *dst++ = mem; \
                        mem += (*__src)->bLength; \
                } \
        } while (0)

#define UVC_COPY_XU_DESCRIPTOR(mem, dst, desc)                                  \
        do {                                                                    \
                *(dst)++ = mem;                                                 \
                memcpy(mem, desc, 22); /* bLength to bNrInPins */               \
                mem += 22;                                                      \
                                                                                \
                memcpy(mem, (desc)->baSourceID, (desc)->bNrInPins);             \
                mem += (desc)->bNrInPins;                                       \
                                                                                \
                memcpy(mem, &(desc)->bControlSize, 1);                          \
                mem++;                                                          \
                                                                                \
                memcpy(mem, (desc)->bmControls, (desc)->bControlSize);          \
                mem += (desc)->bControlSize;                                    \
                                                                                \
                memcpy(mem, &(desc)->iExtension, 1);                            \
                mem++;                                                          \
        } while (0)

static struct usb_descriptor_header **
uvc_copy_descriptors(struct uvc_device *uvc, enum usb_device_speed speed)
{
        struct uvc_input_header_descriptor *uvc_streaming_header;
        struct uvc_header_descriptor *uvc_control_header;
        const struct uvc_descriptor_header * const *uvc_control_desc;
        const struct uvc_descriptor_header * const *uvc_streaming_cls;
        const struct usb_descriptor_header * const *uvc_streaming_std;
        const struct usb_descriptor_header * const *src;
        struct usb_descriptor_header **dst;
        struct usb_descriptor_header **hdr;
        struct uvcg_extension *xu;
        unsigned int control_size;
        unsigned int streaming_size;
        unsigned int n_desc;
        unsigned int bytes;
        void *mem;

        switch (speed) {
        case USB_SPEED_SUPER_PLUS:
        case USB_SPEED_SUPER:
                uvc_control_desc = uvc->desc.ss_control;
                uvc_streaming_cls = uvc->desc.ss_streaming;
                uvc_streaming_std = uvc_ss_streaming;
                break;

        case USB_SPEED_HIGH:
                uvc_control_desc = uvc->desc.fs_control;
                uvc_streaming_cls = uvc->desc.hs_streaming;
                uvc_streaming_std = uvc_hs_streaming;
                break;

        case USB_SPEED_FULL:
        default:
                uvc_control_desc = uvc->desc.fs_control;
                uvc_streaming_cls = uvc->desc.fs_streaming;
                uvc_streaming_std = uvc_fs_streaming;
                break;
        }

        if (!uvc_control_desc || !uvc_streaming_cls)
                return ERR_PTR(-ENODEV);

        /*
         * Descriptors layout
         *
         * uvc_iad
         * uvc_control_intf
         * Class-specific UVC control descriptors
         * uvc_interrupt_ep
         * uvc_interrupt_cs_ep
         * uvc_ss_interrupt_comp (for SS only)
         * uvc_streaming_intf_alt0
         * Class-specific UVC streaming descriptors
         * uvc_{fs|hs}_streaming
         */

        /* Count descriptors and compute their size. */
        control_size = 0;
        streaming_size = 0;
        bytes = uvc_iad.bLength + uvc_control_intf.bLength
              + uvc_streaming_intf_alt0.bLength;

        n_desc = 3;
        if (uvc->enable_interrupt_ep) {
                bytes += uvc_interrupt_ep.bLength + uvc_interrupt_cs_ep.bLength;
                n_desc += 2;

                if (speed == USB_SPEED_SUPER ||
                    speed == USB_SPEED_SUPER_PLUS) {
                        bytes += uvc_ss_interrupt_comp.bLength;
                        n_desc += 1;
                }
        }

        for (src = (const struct usb_descriptor_header **)uvc_control_desc;
             *src; ++src) {
                control_size += (*src)->bLength;
                bytes += (*src)->bLength;
                n_desc++;
        }

        list_for_each_entry(xu, uvc->desc.extension_units, list) {
                control_size += xu->desc.bLength;
                bytes += xu->desc.bLength;
                n_desc++;
        }

        for (src = (const struct usb_descriptor_header **)uvc_streaming_cls;
             *src; ++src) {
                streaming_size += (*src)->bLength;
                bytes += (*src)->bLength;
                n_desc++;
        }
        for (src = uvc_streaming_std; *src; ++src) {
                bytes += (*src)->bLength;
                n_desc++;
        }

        mem = kmalloc((n_desc + 1) * sizeof(*src) + bytes, GFP_KERNEL);
        if (mem == NULL)
                return NULL;

        hdr = mem;
        dst = mem;
        mem += (n_desc + 1) * sizeof(*src);

        /* Copy the descriptors. */
        UVC_COPY_DESCRIPTOR(mem, dst, &uvc_iad);
        UVC_COPY_DESCRIPTOR(mem, dst, &uvc_control_intf);

        uvc_control_header = mem;
        UVC_COPY_DESCRIPTORS(mem, dst,
                (const struct usb_descriptor_header **)uvc_control_desc);

        list_for_each_entry(xu, uvc->desc.extension_units, list)
                UVC_COPY_XU_DESCRIPTOR(mem, dst, &xu->desc);

        uvc_control_header->wTotalLength = cpu_to_le16(control_size);
        uvc_control_header->bInCollection = 1;
        uvc_control_header->baInterfaceNr[0] = uvc->streaming_intf;

        if (uvc->enable_interrupt_ep) {
                UVC_COPY_DESCRIPTOR(mem, dst, &uvc_interrupt_ep);
                if (speed == USB_SPEED_SUPER ||
                    speed == USB_SPEED_SUPER_PLUS)
                        UVC_COPY_DESCRIPTOR(mem, dst, &uvc_ss_interrupt_comp);

                UVC_COPY_DESCRIPTOR(mem, dst, &uvc_interrupt_cs_ep);
        }

        UVC_COPY_DESCRIPTOR(mem, dst, &uvc_streaming_intf_alt0);

        uvc_streaming_header = mem;
        UVC_COPY_DESCRIPTORS(mem, dst,
                (const struct usb_descriptor_header**)uvc_streaming_cls);
        uvc_streaming_header->wTotalLength = cpu_to_le16(streaming_size);
        uvc_streaming_header->bEndpointAddress = uvc->video.ep->address;

        UVC_COPY_DESCRIPTORS(mem, dst, uvc_streaming_std);

        *dst = NULL;
        return hdr;
}

static int
uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
{
        struct usb_composite_dev *cdev = c->cdev;
        struct uvc_device *uvc = to_uvc(f);
        struct uvcg_extension *xu;
        struct usb_string *us;
        unsigned int max_packet_mult;
        unsigned int max_packet_size;
        struct usb_ep *ep;
        struct f_uvc_opts *opts;
        int ret = -EINVAL;

        uvcg_info(f, "%s()\n", __func__);
        scoped_guard(mutex, &uvc->lock)
                uvc->func_unbound = false;

        opts = fi_to_f_uvc_opts(f->fi);
        /* Sanity check the streaming endpoint module parameters. */
        opts->streaming_interval = clamp(opts->streaming_interval, 1U, 16U);
        opts->streaming_maxpacket = clamp(opts->streaming_maxpacket, 1U, 3072U);
        opts->streaming_maxburst = min(opts->streaming_maxburst, 15U);

        /* For SS, wMaxPacketSize has to be 1024 if bMaxBurst is not 0 */
        if (opts->streaming_maxburst &&
            (opts->streaming_maxpacket % 1024) != 0) {
                opts->streaming_maxpacket = roundup(opts->streaming_maxpacket, 1024);
                uvcg_info(f, "overriding streaming_maxpacket to %d\n",
                          opts->streaming_maxpacket);
        }

        /*
         * Fill in the FS/HS/SS Video Streaming specific descriptors from the
         * module parameters.
         *
         * NOTE: We assume that the user knows what they are doing and won't
         * give parameters that their UDC doesn't support.
         */
        if (opts->streaming_maxpacket <= 1024) {
                max_packet_mult = 1;
                max_packet_size = opts->streaming_maxpacket;
        } else if (opts->streaming_maxpacket <= 2048) {
                max_packet_mult = 2;
                max_packet_size = opts->streaming_maxpacket / 2;
        } else {
                max_packet_mult = 3;
                max_packet_size = opts->streaming_maxpacket / 3;
        }

        uvc_fs_streaming_ep.wMaxPacketSize =
                cpu_to_le16(min(opts->streaming_maxpacket, 1023U));
        uvc_fs_streaming_ep.bInterval = opts->streaming_interval;

        uvc_hs_streaming_ep.wMaxPacketSize =
                cpu_to_le16(max_packet_size | ((max_packet_mult - 1) << 11));

        /* A high-bandwidth endpoint must specify a bInterval value of 1 */
        if (max_packet_mult > 1)
                uvc_hs_streaming_ep.bInterval = 1;
        else
                uvc_hs_streaming_ep.bInterval = opts->streaming_interval;

        uvc_ss_streaming_ep.wMaxPacketSize = cpu_to_le16(max_packet_size);
        uvc_ss_streaming_ep.bInterval = opts->streaming_interval;
        uvc_ss_streaming_comp.bmAttributes = max_packet_mult - 1;
        uvc_ss_streaming_comp.bMaxBurst = opts->streaming_maxburst;
        uvc_ss_streaming_comp.wBytesPerInterval =
                cpu_to_le16(max_packet_size * max_packet_mult *
                            (opts->streaming_maxburst + 1));

        /* Allocate endpoints. */
        if (opts->enable_interrupt_ep) {
                ep = usb_ep_autoconfig(cdev->gadget, &uvc_interrupt_ep);
                if (!ep) {
                        uvcg_info(f, "Unable to allocate interrupt EP\n");
                        goto error;
                }
                uvc->interrupt_ep = ep;
                uvc_control_intf.bNumEndpoints = 1;
        }
        uvc->enable_interrupt_ep = opts->enable_interrupt_ep;

        /*
         * gadget_is_{super|dual}speed() API check UDC controller capitblity. It should pass down
         * highest speed endpoint descriptor to UDC controller. So UDC controller driver can reserve
         * enough resource at check_config(), especially mult and maxburst. So UDC driver (such as
         * cdns3) can know need at least (mult + 1) * (maxburst + 1) * wMaxPacketSize internal
         * memory for this uvc functions. This is the only straightforward method to resolve the UDC
         * resource allocation issue in the current gadget framework.
         */
        if (gadget_is_superspeed(c->cdev->gadget))
                ep = usb_ep_autoconfig_ss(cdev->gadget, &uvc_ss_streaming_ep,
                                          &uvc_ss_streaming_comp);
        else if (gadget_is_dualspeed(cdev->gadget))
                ep = usb_ep_autoconfig(cdev->gadget, &uvc_hs_streaming_ep);
        else
                ep = usb_ep_autoconfig(cdev->gadget, &uvc_fs_streaming_ep);

        if (!ep) {
                uvcg_info(f, "Unable to allocate streaming EP\n");
                goto error;
        }
        uvc->video.ep = ep;

        uvc_fs_streaming_ep.bEndpointAddress = uvc->video.ep->address;
        uvc_hs_streaming_ep.bEndpointAddress = uvc->video.ep->address;
        uvc_ss_streaming_ep.bEndpointAddress = uvc->video.ep->address;

        /*
         * XUs can have an arbitrary string descriptor describing them. If they
         * have one pick up the ID.
         */
        list_for_each_entry(xu, &opts->extension_units, list)
                if (xu->string_descriptor_index)
                        xu->desc.iExtension = cdev->usb_strings[xu->string_descriptor_index].id;

        /*
         * We attach the hard-coded defaults incase the user does not provide
         * any more appropriate strings through configfs.
         */
        uvc_en_us_strings[UVC_STRING_CONTROL_IDX].s = opts->function_name;
        us = usb_gstrings_attach(cdev, uvc_function_strings,
                                 ARRAY_SIZE(uvc_en_us_strings));
        if (IS_ERR(us)) {
                ret = PTR_ERR(us);
                goto error;
        }

        uvc_iad.iFunction = opts->iad_index ? cdev->usb_strings[opts->iad_index].id :
                            us[UVC_STRING_CONTROL_IDX].id;
        uvc_streaming_intf_alt0.iInterface = opts->vs0_index ?
                                             cdev->usb_strings[opts->vs0_index].id :
                                             us[UVC_STRING_STREAMING_IDX].id;
        uvc_streaming_intf_alt1.iInterface = opts->vs1_index ?
                                             cdev->usb_strings[opts->vs1_index].id :
                                             us[UVC_STRING_STREAMING_IDX].id;

        /* Allocate interface IDs. */
        if ((ret = usb_interface_id(c, f)) < 0)
                goto error;
        uvc_iad.bFirstInterface = ret;
        uvc_control_intf.bInterfaceNumber = ret;
        uvc->control_intf = ret;
        opts->control_interface = ret;

        if ((ret = usb_interface_id(c, f)) < 0)
                goto error;
        uvc_streaming_intf_alt0.bInterfaceNumber = ret;
        uvc_streaming_intf_alt1.bInterfaceNumber = ret;
        uvc->streaming_intf = ret;
        opts->streaming_interface = ret;

        /* Copy descriptors */
        f->fs_descriptors = uvc_copy_descriptors(uvc, USB_SPEED_FULL);
        if (IS_ERR(f->fs_descriptors)) {
                ret = PTR_ERR(f->fs_descriptors);
                f->fs_descriptors = NULL;
                goto error;
        }

        f->hs_descriptors = uvc_copy_descriptors(uvc, USB_SPEED_HIGH);
        if (IS_ERR(f->hs_descriptors)) {
                ret = PTR_ERR(f->hs_descriptors);
                f->hs_descriptors = NULL;
                goto error;
        }

        f->ss_descriptors = uvc_copy_descriptors(uvc, USB_SPEED_SUPER);
        if (IS_ERR(f->ss_descriptors)) {
                ret = PTR_ERR(f->ss_descriptors);
                f->ss_descriptors = NULL;
                goto error;
        }

        f->ssp_descriptors = uvc_copy_descriptors(uvc, USB_SPEED_SUPER_PLUS);
        if (IS_ERR(f->ssp_descriptors)) {
                ret = PTR_ERR(f->ssp_descriptors);
                f->ssp_descriptors = NULL;
                goto error;
        }

        /* Preallocate control endpoint request. */
        uvc->control_req = usb_ep_alloc_request(cdev->gadget->ep0, GFP_KERNEL);
        uvc->control_buf = kmalloc(UVC_MAX_REQUEST_SIZE, GFP_KERNEL);
        if (uvc->control_req == NULL || uvc->control_buf == NULL) {
                ret = -ENOMEM;
                goto error;
        }

        uvc->control_req->buf = uvc->control_buf;
        uvc->control_req->complete = uvc_function_ep0_complete;
        uvc->control_req->context = uvc;

        if (v4l2_device_register(&cdev->gadget->dev, &uvc->v4l2_dev)) {
                uvcg_err(f, "failed to register V4L2 device\n");
                goto error;
        }

        /* Initialise video. */
        ret = uvcg_video_init(&uvc->video, uvc);
        if (ret < 0)
                goto v4l2_error;

        /* Register a V4L2 device. */
        ret = uvc_register_video(uvc);
        if (ret < 0) {
                uvcg_err(f, "failed to register video device\n");
                goto v4l2_error;
        }

        return 0;

v4l2_error:
        v4l2_device_unregister(&uvc->v4l2_dev);
error:
        if (uvc->control_req)
                usb_ep_free_request(cdev->gadget->ep0, uvc->control_req);
        kfree(uvc->control_buf);

        usb_free_all_descriptors(f);
        return ret;
}

/* --------------------------------------------------------------------------
 * USB gadget function
 */

static void uvc_free_inst(struct usb_function_instance *f)
{
        struct f_uvc_opts *opts = fi_to_f_uvc_opts(f);

        mutex_destroy(&opts->lock);
        kfree(opts);
}

static struct usb_function_instance *uvc_alloc_inst(void)
{
        struct f_uvc_opts *opts;
        struct uvc_camera_terminal_descriptor *cd;
        struct uvc_processing_unit_descriptor *pd;
        struct uvc_output_terminal_descriptor *od;
        struct uvc_descriptor_header **ctl_cls;
        int ret;

        opts = kzalloc_obj(*opts);
        if (!opts)
                return ERR_PTR(-ENOMEM);
        opts->func_inst.free_func_inst = uvc_free_inst;
        mutex_init(&opts->lock);

        cd = &opts->uvc_camera_terminal;
        cd->bLength                     = UVC_DT_CAMERA_TERMINAL_SIZE(3);
        cd->bDescriptorType             = USB_DT_CS_INTERFACE;
        cd->bDescriptorSubType          = UVC_VC_INPUT_TERMINAL;
        cd->bTerminalID                 = 1;
        cd->wTerminalType               = cpu_to_le16(0x0201);
        cd->bAssocTerminal              = 0;
        cd->iTerminal                   = 0;
        cd->wObjectiveFocalLengthMin    = cpu_to_le16(0);
        cd->wObjectiveFocalLengthMax    = cpu_to_le16(0);
        cd->wOcularFocalLength          = cpu_to_le16(0);
        cd->bControlSize                = 3;
        cd->bmControls[0]               = 2;
        cd->bmControls[1]               = 0;
        cd->bmControls[2]               = 0;

        pd = &opts->uvc_processing;
        pd->bLength                     = UVC_DT_PROCESSING_UNIT_SIZE(2);
        pd->bDescriptorType             = USB_DT_CS_INTERFACE;
        pd->bDescriptorSubType          = UVC_VC_PROCESSING_UNIT;
        pd->bUnitID                     = 2;
        pd->bSourceID                   = 1;
        pd->wMaxMultiplier              = cpu_to_le16(16*1024);
        pd->bControlSize                = 2;
        pd->bmControls[0]               = 1;
        pd->bmControls[1]               = 0;
        pd->iProcessing                 = 0;
        pd->bmVideoStandards            = 0;

        od = &opts->uvc_output_terminal;
        od->bLength                     = UVC_DT_OUTPUT_TERMINAL_SIZE;
        od->bDescriptorType             = USB_DT_CS_INTERFACE;
        od->bDescriptorSubType          = UVC_VC_OUTPUT_TERMINAL;
        od->bTerminalID                 = 3;
        od->wTerminalType               = cpu_to_le16(0x0101);
        od->bAssocTerminal              = 0;
        od->bSourceID                   = 2;
        od->iTerminal                   = 0;

        /*
         * With the ability to add XUs to the UVC function graph, we need to be
         * able to allocate unique unit IDs to them. The IDs are 1-based, with
         * the CT, PU and OT above consuming the first 3.
         */
        opts->last_unit_id              = 3;

        /* Prepare fs control class descriptors for configfs-based gadgets */
        ctl_cls = opts->uvc_fs_control_cls;
        ctl_cls[0] = NULL;      /* assigned elsewhere by configfs */
        ctl_cls[1] = (struct uvc_descriptor_header *)cd;
        ctl_cls[2] = (struct uvc_descriptor_header *)pd;
        ctl_cls[3] = (struct uvc_descriptor_header *)od;
        ctl_cls[4] = NULL;      /* NULL-terminate */
        opts->fs_control =
                (const struct uvc_descriptor_header * const *)ctl_cls;

        /* Prepare hs control class descriptors for configfs-based gadgets */
        ctl_cls = opts->uvc_ss_control_cls;
        ctl_cls[0] = NULL;      /* assigned elsewhere by configfs */
        ctl_cls[1] = (struct uvc_descriptor_header *)cd;
        ctl_cls[2] = (struct uvc_descriptor_header *)pd;
        ctl_cls[3] = (struct uvc_descriptor_header *)od;
        ctl_cls[4] = NULL;      /* NULL-terminate */
        opts->ss_control =
                (const struct uvc_descriptor_header * const *)ctl_cls;

        INIT_LIST_HEAD(&opts->extension_units);

        opts->streaming_interval = 1;
        opts->streaming_maxpacket = 1024;
        snprintf(opts->function_name, sizeof(opts->function_name), "UVC Camera");

        ret = uvcg_attach_configfs(opts);
        if (ret < 0) {
                kfree(opts);
                return ERR_PTR(ret);
        }

        return &opts->func_inst;
}

static void uvc_free(struct usb_function *f)
{
        struct uvc_device *uvc = to_uvc(f);
        struct f_uvc_opts *opts = container_of(f->fi, struct f_uvc_opts,
                                               func_inst);
        if (!opts->header)
                config_item_put(&uvc->header->item);
        --opts->refcnt;
        kfree(uvc);
}

static void uvc_function_unbind(struct usb_configuration *c,
                                struct usb_function *f)
{
        DECLARE_COMPLETION_ONSTACK(vdev_release_done);
        struct usb_composite_dev *cdev = c->cdev;
        struct uvc_device *uvc = to_uvc(f);
        struct uvc_video *video = &uvc->video;
        long wait_ret = 1;
        bool connected;

        uvcg_info(f, "%s()\n", __func__);
        scoped_guard(mutex, &uvc->lock) {
                uvc->func_unbound = true;
                uvc->vdev_release_done = &vdev_release_done;
                connected = uvc->func_connected;
        }

        kthread_cancel_work_sync(&video->hw_submit);

        if (video->async_wq)
                destroy_workqueue(video->async_wq);

        /*
         * If we know we're connected via v4l2, then there should be a cleanup
         * of the device from userspace either via UVC_EVENT_DISCONNECT or
         * though the video device removal uevent. Allow some time for the
         * application to close out before things get deleted.
         */
        if (connected) {
                uvcg_dbg(f, "waiting for clean disconnect\n");
                wait_ret = wait_event_interruptible_timeout(uvc->func_connected_queue,
                                uvc->func_connected == false, msecs_to_jiffies(500));
                uvcg_dbg(f, "done waiting with ret: %ld\n", wait_ret);
        }

        device_remove_file(&uvc->vdev.dev, &dev_attr_function_name);
        video_unregister_device(&uvc->vdev);
        v4l2_device_unregister(&uvc->v4l2_dev);

        scoped_guard(mutex, &uvc->lock)
                connected = uvc->func_connected;

        if (connected) {
                /*
                 * Wait for the release to occur to ensure there are no longer any
                 * pending operations that may cause panics when resources are cleaned
                 * up.
                 */
                uvcg_warn(f, "%s no clean disconnect, wait for release\n", __func__);
                wait_ret = wait_event_interruptible_timeout(uvc->func_connected_queue,
                                uvc->func_connected == false, msecs_to_jiffies(1000));
                uvcg_dbg(f, "done waiting for release with ret: %ld\n", wait_ret);
        }

        /* Wait for the video device to be released */
        wait_for_completion(&vdev_release_done);
        uvc->vdev_release_done = NULL;

        usb_ep_free_request(cdev->gadget->ep0, uvc->control_req);
        kfree(uvc->control_buf);

        usb_free_all_descriptors(f);
}

static struct usb_function *uvc_alloc(struct usb_function_instance *fi)
{
        struct uvc_device *uvc;
        struct f_uvc_opts *opts;
        struct uvc_descriptor_header **strm_cls;
        struct config_item *streaming, *header, *h;

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

        mutex_init(&uvc->video.mutex);
        mutex_init(&uvc->lock);
        uvc->func_unbound = true;
        uvc->state = UVC_STATE_DISCONNECTED;
        init_waitqueue_head(&uvc->func_connected_queue);
        opts = fi_to_f_uvc_opts(fi);

        mutex_lock(&opts->lock);
        if (opts->uvc_fs_streaming_cls) {
                strm_cls = opts->uvc_fs_streaming_cls;
                opts->fs_streaming =
                        (const struct uvc_descriptor_header * const *)strm_cls;
        }
        if (opts->uvc_hs_streaming_cls) {
                strm_cls = opts->uvc_hs_streaming_cls;
                opts->hs_streaming =
                        (const struct uvc_descriptor_header * const *)strm_cls;
        }
        if (opts->uvc_ss_streaming_cls) {
                strm_cls = opts->uvc_ss_streaming_cls;
                opts->ss_streaming =
                        (const struct uvc_descriptor_header * const *)strm_cls;
        }

        uvc->desc.fs_control = opts->fs_control;
        uvc->desc.ss_control = opts->ss_control;
        uvc->desc.fs_streaming = opts->fs_streaming;
        uvc->desc.hs_streaming = opts->hs_streaming;
        uvc->desc.ss_streaming = opts->ss_streaming;

        if (opts->header) {
                uvc->header = opts->header;
        } else {
                streaming = config_group_find_item(&opts->func_inst.group, "streaming");
                if (!streaming)
                        goto err_config;

                header = config_group_find_item(to_config_group(streaming), "header");
                config_item_put(streaming);
                if (!header)
                        goto err_config;

                h = config_group_find_item(to_config_group(header), "h");
                config_item_put(header);
                if (!h)
                        goto err_config;

                uvc->header = to_uvcg_streaming_header(h);
                if (!uvc->header->linked) {
                        mutex_unlock(&opts->lock);
                        kfree(uvc);
                        return ERR_PTR(-EBUSY);
                }
        }

        uvc->desc.extension_units = &opts->extension_units;

        ++opts->refcnt;
        mutex_unlock(&opts->lock);

        /* Register the function. */
        uvc->func.name = "uvc";
        uvc->func.bind = uvc_function_bind;
        uvc->func.unbind = uvc_function_unbind;
        uvc->func.get_alt = uvc_function_get_alt;
        uvc->func.set_alt = uvc_function_set_alt;
        uvc->func.disable = uvc_function_disable;
        uvc->func.setup = uvc_function_setup;
        uvc->func.free_func = uvc_free;
        uvc->func.bind_deactivated = true;

        return &uvc->func;

err_config:
        mutex_unlock(&opts->lock);
        kfree(uvc);
        return ERR_PTR(-ENOENT);
}

DECLARE_USB_FUNCTION_INIT(uvc, uvc_alloc_inst, uvc_alloc);
MODULE_DESCRIPTION("USB Video Class Gadget driver");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Laurent Pinchart");