/*
 *      uvc_gadget.c  --  USB Video Class Gadget driver
 *
 *      Copyright (C) 2009-2010
 *          Laurent Pinchart (laurent.pinchart@ideasonboard.com)
 *
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2 of the License, or
 *      (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/string.h>
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.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"

unsigned int uvc_gadget_trace_param;

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

/* module parameters specific to the Video streaming endpoint */
static unsigned int streaming_interval = 1;
module_param(streaming_interval, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(streaming_interval, "1 - 16");

static unsigned int streaming_maxpacket = 1024;
module_param(streaming_maxpacket, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(streaming_maxpacket, "1 - 1023 (FS), 1 - 3072 (hs/ss)");

static unsigned int streaming_maxburst;
module_param(streaming_maxburst, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(streaming_maxburst, "0 - 15 (ss only)");

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

/* string IDs are assigned dynamically */

#define UVC_STRING_CONTROL_IDX                  0
#define UVC_STRING_STREAMING_IDX                1

static struct usb_string uvc_en_us_strings[] = {
        [UVC_STRING_CONTROL_IDX].s = "UVC Camera",
        [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 __initdata = {
        .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 __initdata = {
        .bLength                = USB_DT_INTERFACE_SIZE,
        .bDescriptorType        = USB_DT_INTERFACE,
        .bInterfaceNumber       = UVC_INTF_VIDEO_CONTROL,
        .bAlternateSetting      = 0,
        .bNumEndpoints          = 1,
        .bInterfaceClass        = USB_CLASS_VIDEO,
        .bInterfaceSubClass     = UVC_SC_VIDEOCONTROL,
        .bInterfaceProtocol     = 0x00,
        .iInterface             = 0,
};

static struct usb_endpoint_descriptor uvc_control_ep __initdata = {
        .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_control_comp __initdata = {
        .bLength                = sizeof(uvc_ss_control_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_control_cs_ep __initdata = {
        .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 __initdata = {
        .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 __initdata = {
        .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 __initdata = {
        .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.
         */
        .wMaxPacketSize         = 0,
        .bInterval              = 0,
};

static struct usb_endpoint_descriptor uvc_hs_streaming_ep __initdata = {
        .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.
         */
        .wMaxPacketSize         = 0,
        .bInterval              = 0,
};

static struct usb_endpoint_descriptor uvc_ss_streaming_ep __initdata = {
        .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.
         */
        .wMaxPacketSize         = 0,
        .bInterval              = 0,
};

static struct usb_ss_ep_comp_descriptor uvc_ss_streaming_comp __initdata = {
        .bLength                = sizeof(uvc_ss_streaming_comp),
        .bDescriptorType        = USB_DT_SS_ENDPOINT_COMP,
        /* The following 3 values can be tweaked if necessary. */
        .bMaxBurst              = 0,
        .bmAttributes           = 0,
        .wBytesPerInterval      = cpu_to_le16(1024),
};

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 = req->actual;
                memcpy(&uvc_event->data.data, req->buf, req->actual);
                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;

        /* printk(KERN_INFO "setup request %02x %02x value %04x index %04x %04x\n",
         *      ctrl->bRequestType, ctrl->bRequest, le16_to_cpu(ctrl->wValue),
         *      le16_to_cpu(ctrl->wIndex), le16_to_cpu(ctrl->wLength));
         */

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

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

        memset(&v4l2_event, 0, sizeof(v4l2_event));
        v4l2_event.type = UVC_EVENT_SETUP;
        memcpy(&uvc_event->req, ctrl, sizeof(uvc_event->req));
        v4l2_event_queue(uvc->vdev, &v4l2_event);

        return 0;
}

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

        usb_composite_setup_continue(cdev);
}

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

        INFO(f->config->cdev, "uvc_function_get_alt(%u)\n", interface);

        if (interface == uvc->control_intf)
                return 0;
        else if (interface != uvc->streaming_intf)
                return -EINVAL;
        else
                return uvc->state == UVC_STATE_STREAMING ? 1 : 0;
}

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

        INFO(f->config->cdev, "uvc_function_set_alt(%u, %u)\n", interface, alt);

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

                if (uvc->state == UVC_STATE_DISCONNECTED) {
                        memset(&v4l2_event, 0, sizeof(v4l2_event));
                        v4l2_event.type = UVC_EVENT_CONNECT;
                        uvc_event->speed = f->config->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;

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

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

                uvc->state = UVC_STATE_CONNECTED;
                return 0;

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

                if (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);
                }

                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;

        INFO(f->config->cdev, "uvc_function_disable\n");

        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;
}

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

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

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

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

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

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

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

        /* TODO reference counting. */
        video = video_device_alloc();
        if (video == NULL)
                return -ENOMEM;

        video->parent = &cdev->gadget->dev;
        video->fops = &uvc_v4l2_fops;
        video->release = video_device_release;
        strlcpy(video->name, cdev->gadget->name, sizeof(video->name));

        uvc->vdev = video;
        video_set_drvdata(video, uvc);

        return video_register_device(video, VFL_TYPE_GRABBER, -1);
}

#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)

static struct usb_descriptor_header ** __init
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;
        unsigned int control_size;
        unsigned int streaming_size;
        unsigned int n_desc;
        unsigned int bytes;
        void *mem;

        switch (speed) {
        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;
        }

        /* Descriptors layout
         *
         * uvc_iad
         * uvc_control_intf
         * Class-specific UVC control descriptors
         * uvc_control_ep
         * uvc_control_cs_ep
         * uvc_ss_control_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_control_ep.bLength + uvc_control_cs_ep.bLength
              + uvc_streaming_intf_alt0.bLength;

        if (speed == USB_SPEED_SUPER) {
                bytes += uvc_ss_control_comp.bLength;
                n_desc = 6;
        } else {
                n_desc = 5;
        }

        for (src = (const struct usb_descriptor_header **)uvc_control_desc;
             *src; ++src) {
                control_size += (*src)->bLength;
                bytes += (*src)->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);
        uvc_control_header->wTotalLength = cpu_to_le16(control_size);
        uvc_control_header->bInCollection = 1;
        uvc_control_header->baInterfaceNr[0] = uvc->streaming_intf;

        UVC_COPY_DESCRIPTOR(mem, dst, &uvc_control_ep);
        if (speed == USB_SPEED_SUPER)
                UVC_COPY_DESCRIPTOR(mem, dst, &uvc_ss_control_comp);

        UVC_COPY_DESCRIPTOR(mem, dst, &uvc_control_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 void
uvc_function_unbind(struct usb_configuration *c, struct usb_function *f)
{
        struct usb_composite_dev *cdev = c->cdev;
        struct uvc_device *uvc = to_uvc(f);

        INFO(cdev, "uvc_function_unbind\n");

        video_unregister_device(uvc->vdev);
        uvc->control_ep->driver_data = NULL;
        uvc->video.ep->driver_data = NULL;

        uvc_en_us_strings[UVC_STRING_CONTROL_IDX].id = 0;
        usb_ep_free_request(cdev->gadget->ep0, uvc->control_req);
        kfree(uvc->control_buf);

        usb_free_all_descriptors(f);

        kfree(uvc);
}

static int __init
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);
        unsigned int max_packet_mult;
        unsigned int max_packet_size;
        struct usb_ep *ep;
        int ret = -EINVAL;

        INFO(cdev, "uvc_function_bind\n");

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

        /* 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 (streaming_maxpacket <= 1024) {
                max_packet_mult = 1;
                max_packet_size = streaming_maxpacket;
        } else if (streaming_maxpacket <= 2048) {
                max_packet_mult = 2;
                max_packet_size = streaming_maxpacket / 2;
        } else {
                max_packet_mult = 3;
                max_packet_size = streaming_maxpacket / 3;
        }

        uvc_fs_streaming_ep.wMaxPacketSize = min(streaming_maxpacket, 1023U);
        uvc_fs_streaming_ep.bInterval = streaming_interval;

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

        uvc_ss_streaming_ep.wMaxPacketSize = max_packet_size;
        uvc_ss_streaming_ep.bInterval = streaming_interval;
        uvc_ss_streaming_comp.bmAttributes = max_packet_mult - 1;
        uvc_ss_streaming_comp.bMaxBurst = streaming_maxburst;
        uvc_ss_streaming_comp.wBytesPerInterval =
                max_packet_size * max_packet_mult * streaming_maxburst;

        /* Allocate endpoints. */
        ep = usb_ep_autoconfig(cdev->gadget, &uvc_control_ep);
        if (!ep) {
                INFO(cdev, "Unable to allocate control EP\n");
                goto error;
        }
        uvc->control_ep = ep;
        ep->driver_data = uvc;

        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) {
                INFO(cdev, "Unable to allocate streaming EP\n");
                goto error;
        }
        uvc->video.ep = ep;
        ep->driver_data = uvc;

        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;

        /* 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;

        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;

        /* Copy descriptors */
        f->fs_descriptors = uvc_copy_descriptors(uvc, USB_SPEED_FULL);
        if (gadget_is_dualspeed(cdev->gadget))
                f->hs_descriptors = uvc_copy_descriptors(uvc, USB_SPEED_HIGH);
        if (gadget_is_superspeed(c->cdev->gadget))
                f->ss_descriptors = uvc_copy_descriptors(uvc, USB_SPEED_SUPER);

        /* 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;

        /* Avoid letting this gadget enumerate until the userspace server is
         * active.
         */
        if ((ret = usb_function_deactivate(f)) < 0)
                goto error;

        /* Initialise video. */
        ret = uvc_video_init(&uvc->video);
        if (ret < 0)
                goto error;

        /* Register a V4L2 device. */
        ret = uvc_register_video(uvc);
        if (ret < 0) {
                printk(KERN_INFO "Unable to register video device\n");
                goto error;
        }

        return 0;

error:
        if (uvc->vdev)
                video_device_release(uvc->vdev);

        if (uvc->control_ep)
                uvc->control_ep->driver_data = NULL;
        if (uvc->video.ep)
                uvc->video.ep->driver_data = NULL;

        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
 */

/**
 * uvc_bind_config - add a UVC function to a configuration
 * @c: the configuration to support the UVC instance
 * Context: single threaded during gadget setup
 *
 * Returns zero on success, else negative errno.
 *
 * Caller must have called @uvc_setup(). Caller is also responsible for
 * calling @uvc_cleanup() before module unload.
 */
int __init
uvc_bind_config(struct usb_configuration *c,
                const struct uvc_descriptor_header * const *fs_control,
                const struct uvc_descriptor_header * const *ss_control,
                const struct uvc_descriptor_header * const *fs_streaming,
                const struct uvc_descriptor_header * const *hs_streaming,
                const struct uvc_descriptor_header * const *ss_streaming)
{
        struct uvc_device *uvc;
        int ret = 0;

        /* TODO Check if the USB device controller supports the required
         * features.
         */
        if (!gadget_is_dualspeed(c->cdev->gadget))
                return -EINVAL;

        uvc = kzalloc(sizeof(*uvc), GFP_KERNEL);
        if (uvc == NULL)
                return -ENOMEM;

        uvc->state = UVC_STATE_DISCONNECTED;

        /* Validate the descriptors. */
        if (fs_control == NULL || fs_control[0] == NULL ||
            fs_control[0]->bDescriptorSubType != UVC_VC_HEADER)
                goto error;

        if (ss_control == NULL || ss_control[0] == NULL ||
            ss_control[0]->bDescriptorSubType != UVC_VC_HEADER)
                goto error;

        if (fs_streaming == NULL || fs_streaming[0] == NULL ||
            fs_streaming[0]->bDescriptorSubType != UVC_VS_INPUT_HEADER)
                goto error;

        if (hs_streaming == NULL || hs_streaming[0] == NULL ||
            hs_streaming[0]->bDescriptorSubType != UVC_VS_INPUT_HEADER)
                goto error;

        if (ss_streaming == NULL || ss_streaming[0] == NULL ||
            ss_streaming[0]->bDescriptorSubType != UVC_VS_INPUT_HEADER)
                goto error;

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

        /* String descriptors are global, we only need to allocate string IDs
         * for the first UVC function. UVC functions beyond the first (if any)
         * will reuse the same IDs.
         */
        if (uvc_en_us_strings[UVC_STRING_CONTROL_IDX].id == 0) {
                ret = usb_string_ids_tab(c->cdev, uvc_en_us_strings);
                if (ret)
                        goto error;
                uvc_iad.iFunction =
                        uvc_en_us_strings[UVC_STRING_CONTROL_IDX].id;
                uvc_control_intf.iInterface =
                        uvc_en_us_strings[UVC_STRING_CONTROL_IDX].id;
                ret = uvc_en_us_strings[UVC_STRING_STREAMING_IDX].id;
                uvc_streaming_intf_alt0.iInterface = ret;
                uvc_streaming_intf_alt1.iInterface = ret;
        }

        /* Register the function. */
        uvc->func.name = "uvc";
        uvc->func.strings = uvc_function_strings;
        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;

        ret = usb_add_function(c, &uvc->func);
        if (ret)
                kfree(uvc);

        return ret;

error:
        kfree(uvc);
        return ret;
}

module_param_named(trace, uvc_gadget_trace_param, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(trace, "Trace level bitmask");