/*
 *      uvc_driver.c  --  USB Video Class driver
 *
 *      Copyright (C) 2005-2009
 *          Laurent Pinchart (laurent.pinchart@skynet.be)
 *
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2 of the License, or
 *      (at your option) any later version.
 *
 */

/*
 * This driver aims to support video input and ouput devices compliant with the
 * 'USB Video Class' specification.
 *
 * The driver doesn't support the deprecated v4l1 interface. It implements the
 * mmap capture method only, and doesn't do any image format conversion in
 * software. If your user-space application doesn't support YUYV or MJPEG, fix
 * it :-). Please note that the MJPEG data have been stripped from their
 * Huffman tables (DHT marker), you will need to add it back if your JPEG
 * codec can't handle MJPEG data.
 */

#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/videodev2.h>
#include <linux/vmalloc.h>
#include <linux/wait.h>
#include <asm/atomic.h>
#include <asm/unaligned.h>

#include <media/v4l2-common.h>

#include "uvcvideo.h"

#define DRIVER_AUTHOR           "Laurent Pinchart <laurent.pinchart@skynet.be>"
#define DRIVER_DESC             "USB Video Class driver"
#ifndef DRIVER_VERSION
#define DRIVER_VERSION          "v0.1.0"
#endif

unsigned int uvc_no_drop_param;
static unsigned int uvc_quirks_param;
unsigned int uvc_trace_param;

/* ------------------------------------------------------------------------
 * Video formats
 */

static struct uvc_format_desc uvc_fmts[] = {
        {
                .name           = "YUV 4:2:2 (YUYV)",
                .guid           = UVC_GUID_FORMAT_YUY2,
                .fcc            = V4L2_PIX_FMT_YUYV,
        },
        {
                .name           = "YUV 4:2:0 (NV12)",
                .guid           = UVC_GUID_FORMAT_NV12,
                .fcc            = V4L2_PIX_FMT_NV12,
        },
        {
                .name           = "MJPEG",
                .guid           = UVC_GUID_FORMAT_MJPEG,
                .fcc            = V4L2_PIX_FMT_MJPEG,
        },
        {
                .name           = "YVU 4:2:0 (YV12)",
                .guid           = UVC_GUID_FORMAT_YV12,
                .fcc            = V4L2_PIX_FMT_YVU420,
        },
        {
                .name           = "YUV 4:2:0 (I420)",
                .guid           = UVC_GUID_FORMAT_I420,
                .fcc            = V4L2_PIX_FMT_YUV420,
        },
        {
                .name           = "YUV 4:2:2 (UYVY)",
                .guid           = UVC_GUID_FORMAT_UYVY,
                .fcc            = V4L2_PIX_FMT_UYVY,
        },
        {
                .name           = "Greyscale",
                .guid           = UVC_GUID_FORMAT_Y800,
                .fcc            = V4L2_PIX_FMT_GREY,
        },
        {
                .name           = "RGB Bayer",
                .guid           = UVC_GUID_FORMAT_BY8,
                .fcc            = V4L2_PIX_FMT_SBGGR8,
        },
};

/* ------------------------------------------------------------------------
 * Utility functions
 */

struct usb_host_endpoint *uvc_find_endpoint(struct usb_host_interface *alts,
                __u8 epaddr)
{
        struct usb_host_endpoint *ep;
        unsigned int i;

        for (i = 0; i < alts->desc.bNumEndpoints; ++i) {
                ep = &alts->endpoint[i];
                if (ep->desc.bEndpointAddress == epaddr)
                        return ep;
        }

        return NULL;
}

static struct uvc_format_desc *uvc_format_by_guid(const __u8 guid[16])
{
        unsigned int len = ARRAY_SIZE(uvc_fmts);
        unsigned int i;

        for (i = 0; i < len; ++i) {
                if (memcmp(guid, uvc_fmts[i].guid, 16) == 0)
                        return &uvc_fmts[i];
        }

        return NULL;
}

static __u32 uvc_colorspace(const __u8 primaries)
{
        static const __u8 colorprimaries[] = {
                0,
                V4L2_COLORSPACE_SRGB,
                V4L2_COLORSPACE_470_SYSTEM_M,
                V4L2_COLORSPACE_470_SYSTEM_BG,
                V4L2_COLORSPACE_SMPTE170M,
                V4L2_COLORSPACE_SMPTE240M,
        };

        if (primaries < ARRAY_SIZE(colorprimaries))
                return colorprimaries[primaries];

        return 0;
}

/* Simplify a fraction using a simple continued fraction decomposition. The
 * idea here is to convert fractions such as 333333/10000000 to 1/30 using
 * 32 bit arithmetic only. The algorithm is not perfect and relies upon two
 * arbitrary parameters to remove non-significative terms from the simple
 * continued fraction decomposition. Using 8 and 333 for n_terms and threshold
 * respectively seems to give nice results.
 */
void uvc_simplify_fraction(uint32_t *numerator, uint32_t *denominator,
                unsigned int n_terms, unsigned int threshold)
{
        uint32_t *an;
        uint32_t x, y, r;
        unsigned int i, n;

        an = kmalloc(n_terms * sizeof *an, GFP_KERNEL);
        if (an == NULL)
                return;

        /* Convert the fraction to a simple continued fraction. See
         * http://mathforum.org/dr.math/faq/faq.fractions.html
         * Stop if the current term is bigger than or equal to the given
         * threshold.
         */
        x = *numerator;
        y = *denominator;

        for (n = 0; n < n_terms && y != 0; ++n) {
                an[n] = x / y;
                if (an[n] >= threshold) {
                        if (n < 2)
                                n++;
                        break;
                }

                r = x - an[n] * y;
                x = y;
                y = r;
        }

        /* Expand the simple continued fraction back to an integer fraction. */
        x = 0;
        y = 1;

        for (i = n; i > 0; --i) {
                r = y;
                y = an[i-1] * y + x;
                x = r;
        }

        *numerator = y;
        *denominator = x;
        kfree(an);
}

/* Convert a fraction to a frame interval in 100ns multiples. The idea here is
 * to compute numerator / denominator * 10000000 using 32 bit fixed point
 * arithmetic only.
 */
uint32_t uvc_fraction_to_interval(uint32_t numerator, uint32_t denominator)
{
        uint32_t multiplier;

        /* Saturate the result if the operation would overflow. */
        if (denominator == 0 ||
            numerator/denominator >= ((uint32_t)-1)/10000000)
                return (uint32_t)-1;

        /* Divide both the denominator and the multiplier by two until
         * numerator * multiplier doesn't overflow. If anyone knows a better
         * algorithm please let me know.
         */
        multiplier = 10000000;
        while (numerator > ((uint32_t)-1)/multiplier) {
                multiplier /= 2;
                denominator /= 2;
        }

        return denominator ? numerator * multiplier / denominator : 0;
}

/* ------------------------------------------------------------------------
 * Terminal and unit management
 */

static struct uvc_entity *uvc_entity_by_id(struct uvc_device *dev, int id)
{
        struct uvc_entity *entity;

        list_for_each_entry(entity, &dev->entities, list) {
                if (entity->id == id)
                        return entity;
        }

        return NULL;
}

static struct uvc_entity *uvc_entity_by_reference(struct uvc_device *dev,
        int id, struct uvc_entity *entity)
{
        unsigned int i;

        if (entity == NULL)
                entity = list_entry(&dev->entities, struct uvc_entity, list);

        list_for_each_entry_continue(entity, &dev->entities, list) {
                switch (UVC_ENTITY_TYPE(entity)) {
                case UVC_TT_STREAMING:
                        if (entity->output.bSourceID == id)
                                return entity;
                        break;

                case UVC_VC_PROCESSING_UNIT:
                        if (entity->processing.bSourceID == id)
                                return entity;
                        break;

                case UVC_VC_SELECTOR_UNIT:
                        for (i = 0; i < entity->selector.bNrInPins; ++i)
                                if (entity->selector.baSourceID[i] == id)
                                        return entity;
                        break;

                case UVC_VC_EXTENSION_UNIT:
                        for (i = 0; i < entity->extension.bNrInPins; ++i)
                                if (entity->extension.baSourceID[i] == id)
                                        return entity;
                        break;
                }
        }

        return NULL;
}

static struct uvc_streaming *uvc_stream_by_id(struct uvc_device *dev, int id)
{
        struct uvc_streaming *stream;

        list_for_each_entry(stream, &dev->streams, list) {
                if (stream->header.bTerminalLink == id)
                        return stream;
        }

        return NULL;
}

/* ------------------------------------------------------------------------
 * Descriptors parsing
 */

static int uvc_parse_format(struct uvc_device *dev,
        struct uvc_streaming *streaming, struct uvc_format *format,
        __u32 **intervals, unsigned char *buffer, int buflen)
{
        struct usb_interface *intf = streaming->intf;
        struct usb_host_interface *alts = intf->cur_altsetting;
        struct uvc_format_desc *fmtdesc;
        struct uvc_frame *frame;
        const unsigned char *start = buffer;
        unsigned int interval;
        unsigned int i, n;
        __u8 ftype;

        format->type = buffer[2];
        format->index = buffer[3];

        switch (buffer[2]) {
        case UVC_VS_FORMAT_UNCOMPRESSED:
        case UVC_VS_FORMAT_FRAME_BASED:
                n = buffer[2] == UVC_VS_FORMAT_UNCOMPRESSED ? 27 : 28;
                if (buflen < n) {
                        uvc_trace(UVC_TRACE_DESCR, "device %d videostreaming "
                               "interface %d FORMAT error\n",
                               dev->udev->devnum,
                               alts->desc.bInterfaceNumber);
                        return -EINVAL;
                }

                /* Find the format descriptor from its GUID. */
                fmtdesc = uvc_format_by_guid(&buffer[5]);

                if (fmtdesc != NULL) {
                        strlcpy(format->name, fmtdesc->name,
                                sizeof format->name);
                        format->fcc = fmtdesc->fcc;
                } else {
                        uvc_printk(KERN_INFO, "Unknown video format "
                                UVC_GUID_FORMAT "\n",
                                UVC_GUID_ARGS(&buffer[5]));
                        snprintf(format->name, sizeof format->name,
                                UVC_GUID_FORMAT, UVC_GUID_ARGS(&buffer[5]));
                        format->fcc = 0;
                }

                format->bpp = buffer[21];
                if (buffer[2] == UVC_VS_FORMAT_UNCOMPRESSED) {
                        ftype = UVC_VS_FRAME_UNCOMPRESSED;
                } else {
                        ftype = UVC_VS_FRAME_FRAME_BASED;
                        if (buffer[27])
                                format->flags = UVC_FMT_FLAG_COMPRESSED;
                }
                break;

        case UVC_VS_FORMAT_MJPEG:
                if (buflen < 11) {
                        uvc_trace(UVC_TRACE_DESCR, "device %d videostreaming "
                               "interface %d FORMAT error\n",
                               dev->udev->devnum,
                               alts->desc.bInterfaceNumber);
                        return -EINVAL;
                }

                strlcpy(format->name, "MJPEG", sizeof format->name);
                format->fcc = V4L2_PIX_FMT_MJPEG;
                format->flags = UVC_FMT_FLAG_COMPRESSED;
                format->bpp = 0;
                ftype = UVC_VS_FRAME_MJPEG;
                break;

        case UVC_VS_FORMAT_DV:
                if (buflen < 9) {
                        uvc_trace(UVC_TRACE_DESCR, "device %d videostreaming "
                               "interface %d FORMAT error\n",
                               dev->udev->devnum,
                               alts->desc.bInterfaceNumber);
                        return -EINVAL;
                }

                switch (buffer[8] & 0x7f) {
                case 0:
                        strlcpy(format->name, "SD-DV", sizeof format->name);
                        break;
                case 1:
                        strlcpy(format->name, "SDL-DV", sizeof format->name);
                        break;
                case 2:
                        strlcpy(format->name, "HD-DV", sizeof format->name);
                        break;
                default:
                        uvc_trace(UVC_TRACE_DESCR, "device %d videostreaming "
                               "interface %d: unknown DV format %u\n",
                               dev->udev->devnum,
                               alts->desc.bInterfaceNumber, buffer[8]);
                        return -EINVAL;
                }

                strlcat(format->name, buffer[8] & (1 << 7) ? " 60Hz" : " 50Hz",
                        sizeof format->name);

                format->fcc = V4L2_PIX_FMT_DV;
                format->flags = UVC_FMT_FLAG_COMPRESSED | UVC_FMT_FLAG_STREAM;
                format->bpp = 0;
                ftype = 0;

                /* Create a dummy frame descriptor. */
                frame = &format->frame[0];
                memset(&format->frame[0], 0, sizeof format->frame[0]);
                frame->bFrameIntervalType = 1;
                frame->dwDefaultFrameInterval = 1;
                frame->dwFrameInterval = *intervals;
                *(*intervals)++ = 1;
                format->nframes = 1;
                break;

        case UVC_VS_FORMAT_MPEG2TS:
        case UVC_VS_FORMAT_STREAM_BASED:
                /* Not supported yet. */
        default:
                uvc_trace(UVC_TRACE_DESCR, "device %d videostreaming "
                       "interface %d unsupported format %u\n",
                       dev->udev->devnum, alts->desc.bInterfaceNumber,
                       buffer[2]);
                return -EINVAL;
        }

        uvc_trace(UVC_TRACE_DESCR, "Found format %s.\n", format->name);

        buflen -= buffer[0];
        buffer += buffer[0];

        /* Parse the frame descriptors. Only uncompressed, MJPEG and frame
         * based formats have frame descriptors.
         */
        while (buflen > 2 && buffer[2] == ftype) {
                frame = &format->frame[format->nframes];
                if (ftype != UVC_VS_FRAME_FRAME_BASED)
                        n = buflen > 25 ? buffer[25] : 0;
                else
                        n = buflen > 21 ? buffer[21] : 0;

                n = n ? n : 3;

                if (buflen < 26 + 4*n) {
                        uvc_trace(UVC_TRACE_DESCR, "device %d videostreaming "
                               "interface %d FRAME error\n", dev->udev->devnum,
                               alts->desc.bInterfaceNumber);
                        return -EINVAL;
                }

                frame->bFrameIndex = buffer[3];
                frame->bmCapabilities = buffer[4];
                frame->wWidth = get_unaligned_le16(&buffer[5]);
                frame->wHeight = get_unaligned_le16(&buffer[7]);
                frame->dwMinBitRate = get_unaligned_le32(&buffer[9]);
                frame->dwMaxBitRate = get_unaligned_le32(&buffer[13]);
                if (ftype != UVC_VS_FRAME_FRAME_BASED) {
                        frame->dwMaxVideoFrameBufferSize =
                                get_unaligned_le32(&buffer[17]);
                        frame->dwDefaultFrameInterval =
                                get_unaligned_le32(&buffer[21]);
                        frame->bFrameIntervalType = buffer[25];
                } else {
                        frame->dwMaxVideoFrameBufferSize = 0;
                        frame->dwDefaultFrameInterval =
                                get_unaligned_le32(&buffer[17]);
                        frame->bFrameIntervalType = buffer[21];
                }
                frame->dwFrameInterval = *intervals;

                /* Several UVC chipsets screw up dwMaxVideoFrameBufferSize
                 * completely. Observed behaviours range from setting the
                 * value to 1.1x the actual frame size to hardwiring the
                 * 16 low bits to 0. This results in a higher than necessary
                 * memory usage as well as a wrong image size information. For
                 * uncompressed formats this can be fixed by computing the
                 * value from the frame size.
                 */
                if (!(format->flags & UVC_FMT_FLAG_COMPRESSED))
                        frame->dwMaxVideoFrameBufferSize = format->bpp
                                * frame->wWidth * frame->wHeight / 8;

                /* Some bogus devices report dwMinFrameInterval equal to
                 * dwMaxFrameInterval and have dwFrameIntervalStep set to
                 * zero. Setting all null intervals to 1 fixes the problem and
                 * some other divisions by zero that could happen.
                 */
                for (i = 0; i < n; ++i) {
                        interval = get_unaligned_le32(&buffer[26+4*i]);
                        *(*intervals)++ = interval ? interval : 1;
                }

                /* Make sure that the default frame interval stays between
                 * the boundaries.
                 */
                n -= frame->bFrameIntervalType ? 1 : 2;
                frame->dwDefaultFrameInterval =
                        min(frame->dwFrameInterval[n],
                            max(frame->dwFrameInterval[0],
                                frame->dwDefaultFrameInterval));

                uvc_trace(UVC_TRACE_DESCR, "- %ux%u (%u.%u fps)\n",
                        frame->wWidth, frame->wHeight,
                        10000000/frame->dwDefaultFrameInterval,
                        (100000000/frame->dwDefaultFrameInterval)%10);

                format->nframes++;
                buflen -= buffer[0];
                buffer += buffer[0];
        }

        if (buflen > 2 && buffer[2] == UVC_VS_STILL_IMAGE_FRAME) {
                buflen -= buffer[0];
                buffer += buffer[0];
        }

        if (buflen > 2 && buffer[2] == UVC_VS_COLORFORMAT) {
                if (buflen < 6) {
                        uvc_trace(UVC_TRACE_DESCR, "device %d videostreaming "
                               "interface %d COLORFORMAT error\n",
                               dev->udev->devnum,
                               alts->desc.bInterfaceNumber);
                        return -EINVAL;
                }

                format->colorspace = uvc_colorspace(buffer[3]);

                buflen -= buffer[0];
                buffer += buffer[0];
        }

        return buffer - start;
}

static int uvc_parse_streaming(struct uvc_device *dev,
        struct usb_interface *intf)
{
        struct uvc_streaming *streaming = NULL;
        struct uvc_format *format;
        struct uvc_frame *frame;
        struct usb_host_interface *alts = &intf->altsetting[0];
        unsigned char *_buffer, *buffer = alts->extra;
        int _buflen, buflen = alts->extralen;
        unsigned int nformats = 0, nframes = 0, nintervals = 0;
        unsigned int size, i, n, p;
        __u32 *interval;
        __u16 psize;
        int ret = -EINVAL;

        if (intf->cur_altsetting->desc.bInterfaceSubClass
                != UVC_SC_VIDEOSTREAMING) {
                uvc_trace(UVC_TRACE_DESCR, "device %d interface %d isn't a "
                        "video streaming interface\n", dev->udev->devnum,
                        intf->altsetting[0].desc.bInterfaceNumber);
                return -EINVAL;
        }

        if (usb_driver_claim_interface(&uvc_driver.driver, intf, dev)) {
                uvc_trace(UVC_TRACE_DESCR, "device %d interface %d is already "
                        "claimed\n", dev->udev->devnum,
                        intf->altsetting[0].desc.bInterfaceNumber);
                return -EINVAL;
        }

        streaming = kzalloc(sizeof *streaming, GFP_KERNEL);
        if (streaming == NULL) {
                usb_driver_release_interface(&uvc_driver.driver, intf);
                return -EINVAL;
        }

        mutex_init(&streaming->mutex);
        streaming->dev = dev;
        streaming->intf = usb_get_intf(intf);
        streaming->intfnum = intf->cur_altsetting->desc.bInterfaceNumber;

        /* The Pico iMage webcam has its class-specific interface descriptors
         * after the endpoint descriptors.
         */
        if (buflen == 0) {
                for (i = 0; i < alts->desc.bNumEndpoints; ++i) {
                        struct usb_host_endpoint *ep = &alts->endpoint[i];

                        if (ep->extralen == 0)
                                continue;

                        if (ep->extralen > 2 &&
                            ep->extra[1] == USB_DT_CS_INTERFACE) {
                                uvc_trace(UVC_TRACE_DESCR, "trying extra data "
                                        "from endpoint %u.\n", i);
                                buffer = alts->endpoint[i].extra;
                                buflen = alts->endpoint[i].extralen;
                                break;
                        }
                }
        }

        /* Skip the standard interface descriptors. */
        while (buflen > 2 && buffer[1] != USB_DT_CS_INTERFACE) {
                buflen -= buffer[0];
                buffer += buffer[0];
        }

        if (buflen <= 2) {
                uvc_trace(UVC_TRACE_DESCR, "no class-specific streaming "
                        "interface descriptors found.\n");
                goto error;
        }

        /* Parse the header descriptor. */
        switch (buffer[2]) {
        case UVC_VS_OUTPUT_HEADER:
                streaming->type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
                size = 9;
                break;

        case UVC_VS_INPUT_HEADER:
                streaming->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
                size = 13;
                break;

        default:
                uvc_trace(UVC_TRACE_DESCR, "device %d videostreaming interface "
                        "%d HEADER descriptor not found.\n", dev->udev->devnum,
                        alts->desc.bInterfaceNumber);
                goto error;
        }

        p = buflen >= 4 ? buffer[3] : 0;
        n = buflen >= size ? buffer[size-1] : 0;

        if (buflen < size + p*n) {
                uvc_trace(UVC_TRACE_DESCR, "device %d videostreaming "
                        "interface %d HEADER descriptor is invalid.\n",
                        dev->udev->devnum, alts->desc.bInterfaceNumber);
                goto error;
        }

        streaming->header.bNumFormats = p;
        streaming->header.bEndpointAddress = buffer[6];
        if (buffer[2] == UVC_VS_INPUT_HEADER) {
                streaming->header.bmInfo = buffer[7];
                streaming->header.bTerminalLink = buffer[8];
                streaming->header.bStillCaptureMethod = buffer[9];
                streaming->header.bTriggerSupport = buffer[10];
                streaming->header.bTriggerUsage = buffer[11];
        } else {
                streaming->header.bTerminalLink = buffer[7];
        }
        streaming->header.bControlSize = n;

        streaming->header.bmaControls = kmalloc(p*n, GFP_KERNEL);
        if (streaming->header.bmaControls == NULL) {
                ret = -ENOMEM;
                goto error;
        }

        memcpy(streaming->header.bmaControls, &buffer[size], p*n);

        buflen -= buffer[0];
        buffer += buffer[0];

        _buffer = buffer;
        _buflen = buflen;

        /* Count the format and frame descriptors. */
        while (_buflen > 2 && _buffer[1] == USB_DT_CS_INTERFACE) {
                switch (_buffer[2]) {
                case UVC_VS_FORMAT_UNCOMPRESSED:
                case UVC_VS_FORMAT_MJPEG:
                case UVC_VS_FORMAT_FRAME_BASED:
                        nformats++;
                        break;

                case UVC_VS_FORMAT_DV:
                        /* DV format has no frame descriptor. We will create a
                         * dummy frame descriptor with a dummy frame interval.
                         */
                        nformats++;
                        nframes++;
                        nintervals++;
                        break;

                case UVC_VS_FORMAT_MPEG2TS:
                case UVC_VS_FORMAT_STREAM_BASED:
                        uvc_trace(UVC_TRACE_DESCR, "device %d videostreaming "
                                "interface %d FORMAT %u is not supported.\n",
                                dev->udev->devnum,
                                alts->desc.bInterfaceNumber, _buffer[2]);
                        break;

                case UVC_VS_FRAME_UNCOMPRESSED:
                case UVC_VS_FRAME_MJPEG:
                        nframes++;
                        if (_buflen > 25)
                                nintervals += _buffer[25] ? _buffer[25] : 3;
                        break;

                case UVC_VS_FRAME_FRAME_BASED:
                        nframes++;
                        if (_buflen > 21)
                                nintervals += _buffer[21] ? _buffer[21] : 3;
                        break;
                }

                _buflen -= _buffer[0];
                _buffer += _buffer[0];
        }

        if (nformats == 0) {
                uvc_trace(UVC_TRACE_DESCR, "device %d videostreaming interface "
                        "%d has no supported formats defined.\n",
                        dev->udev->devnum, alts->desc.bInterfaceNumber);
                goto error;
        }

        size = nformats * sizeof *format + nframes * sizeof *frame
             + nintervals * sizeof *interval;
        format = kzalloc(size, GFP_KERNEL);
        if (format == NULL) {
                ret = -ENOMEM;
                goto error;
        }

        frame = (struct uvc_frame *)&format[nformats];
        interval = (__u32 *)&frame[nframes];

        streaming->format = format;
        streaming->nformats = nformats;

        /* Parse the format descriptors. */
        while (buflen > 2 && buffer[1] == USB_DT_CS_INTERFACE) {
                switch (buffer[2]) {
                case UVC_VS_FORMAT_UNCOMPRESSED:
                case UVC_VS_FORMAT_MJPEG:
                case UVC_VS_FORMAT_DV:
                case UVC_VS_FORMAT_FRAME_BASED:
                        format->frame = frame;
                        ret = uvc_parse_format(dev, streaming, format,
                                &interval, buffer, buflen);
                        if (ret < 0)
                                goto error;

                        frame += format->nframes;
                        format++;

                        buflen -= ret;
                        buffer += ret;
                        continue;

                default:
                        break;
                }

                buflen -= buffer[0];
                buffer += buffer[0];
        }

        /* Parse the alternate settings to find the maximum bandwidth. */
        for (i = 0; i < intf->num_altsetting; ++i) {
                struct usb_host_endpoint *ep;
                alts = &intf->altsetting[i];
                ep = uvc_find_endpoint(alts,
                                streaming->header.bEndpointAddress);
                if (ep == NULL)
                        continue;

                psize = le16_to_cpu(ep->desc.wMaxPacketSize);
                psize = (psize & 0x07ff) * (1 + ((psize >> 11) & 3));
                if (psize > streaming->maxpsize)
                        streaming->maxpsize = psize;
        }

        list_add_tail(&streaming->list, &dev->streams);
        return 0;

error:
        usb_driver_release_interface(&uvc_driver.driver, intf);
        usb_put_intf(intf);
        kfree(streaming->format);
        kfree(streaming->header.bmaControls);
        kfree(streaming);
        return ret;
}

/* Parse vendor-specific extensions. */
static int uvc_parse_vendor_control(struct uvc_device *dev,
        const unsigned char *buffer, int buflen)
{
        struct usb_device *udev = dev->udev;
        struct usb_host_interface *alts = dev->intf->cur_altsetting;
        struct uvc_entity *unit;
        unsigned int n, p;
        int handled = 0;

        switch (le16_to_cpu(dev->udev->descriptor.idVendor)) {
        case 0x046d:            /* Logitech */
                if (buffer[1] != 0x41 || buffer[2] != 0x01)
                        break;

                /* Logitech implements several vendor specific functions
                 * through vendor specific extension units (LXU).
                 *
                 * The LXU descriptors are similar to XU descriptors
                 * (see "USB Device Video Class for Video Devices", section
                 * 3.7.2.6 "Extension Unit Descriptor") with the following
                 * differences:
                 *
                 * ----------------------------------------------------------
                 * 0            bLength         1        Number
                 *      Size of this descriptor, in bytes: 24+p+n*2
                 * ----------------------------------------------------------
                 * 23+p+n       bmControlsType  N       Bitmap
                 *      Individual bits in the set are defined:
                 *      0: Absolute
                 *      1: Relative
                 *
                 *      This bitset is mapped exactly the same as bmControls.
                 * ----------------------------------------------------------
                 * 23+p+n*2     bReserved       1       Boolean
                 * ----------------------------------------------------------
                 * 24+p+n*2     iExtension      1       Index
                 *      Index of a string descriptor that describes this
                 *      extension unit.
                 * ----------------------------------------------------------
                 */
                p = buflen >= 22 ? buffer[21] : 0;
                n = buflen >= 25 + p ? buffer[22+p] : 0;

                if (buflen < 25 + p + 2*n) {
                        uvc_trace(UVC_TRACE_DESCR, "device %d videocontrol "
                                "interface %d EXTENSION_UNIT error\n",
                                udev->devnum, alts->desc.bInterfaceNumber);
                        break;
                }

                unit = kzalloc(sizeof *unit + p + 2*n, GFP_KERNEL);
                if (unit == NULL)
                        return -ENOMEM;

                unit->id = buffer[3];
                unit->type = UVC_VC_EXTENSION_UNIT;
                memcpy(unit->extension.guidExtensionCode, &buffer[4], 16);
                unit->extension.bNumControls = buffer[20];
                unit->extension.bNrInPins = get_unaligned_le16(&buffer[21]);
                unit->extension.baSourceID = (__u8 *)unit + sizeof *unit;
                memcpy(unit->extension.baSourceID, &buffer[22], p);
                unit->extension.bControlSize = buffer[22+p];
                unit->extension.bmControls = (__u8 *)unit + sizeof *unit + p;
                unit->extension.bmControlsType = (__u8 *)unit + sizeof *unit
                                               + p + n;
                memcpy(unit->extension.bmControls, &buffer[23+p], 2*n);

                if (buffer[24+p+2*n] != 0)
                        usb_string(udev, buffer[24+p+2*n], unit->name,
                                   sizeof unit->name);
                else
                        sprintf(unit->name, "Extension %u", buffer[3]);

                list_add_tail(&unit->list, &dev->entities);
                handled = 1;
                break;
        }

        return handled;
}

static int uvc_parse_standard_control(struct uvc_device *dev,
        const unsigned char *buffer, int buflen)
{
        struct usb_device *udev = dev->udev;
        struct uvc_entity *unit, *term;
        struct usb_interface *intf;
        struct usb_host_interface *alts = dev->intf->cur_altsetting;
        unsigned int i, n, p, len;
        __u16 type;

        switch (buffer[2]) {
        case UVC_VC_HEADER:
                n = buflen >= 12 ? buffer[11] : 0;

                if (buflen < 12 || buflen < 12 + n) {
                        uvc_trace(UVC_TRACE_DESCR, "device %d videocontrol "
                                "interface %d HEADER error\n", udev->devnum,
                                alts->desc.bInterfaceNumber);
                        return -EINVAL;
                }

                dev->uvc_version = get_unaligned_le16(&buffer[3]);
                dev->clock_frequency = get_unaligned_le32(&buffer[7]);

                /* Parse all USB Video Streaming interfaces. */
                for (i = 0; i < n; ++i) {
                        intf = usb_ifnum_to_if(udev, buffer[12+i]);
                        if (intf == NULL) {
                                uvc_trace(UVC_TRACE_DESCR, "device %d "
                                        "interface %d doesn't exists\n",
                                        udev->devnum, i);
                                continue;
                        }

                        uvc_parse_streaming(dev, intf);
                }
                break;

        case UVC_VC_INPUT_TERMINAL:
                if (buflen < 8) {
                        uvc_trace(UVC_TRACE_DESCR, "device %d videocontrol "
                                "interface %d INPUT_TERMINAL error\n",
                                udev->devnum, alts->desc.bInterfaceNumber);
                        return -EINVAL;
                }

                /* Make sure the terminal type MSB is not null, otherwise it
                 * could be confused with a unit.
                 */
                type = get_unaligned_le16(&buffer[4]);
                if ((type & 0xff00) == 0) {
                        uvc_trace(UVC_TRACE_DESCR, "device %d videocontrol "
                                "interface %d INPUT_TERMINAL %d has invalid "
                                "type 0x%04x, skipping\n", udev->devnum,
                                alts->desc.bInterfaceNumber,
                                buffer[3], type);
                        return 0;
                }

                n = 0;
                p = 0;
                len = 8;

                if (type == UVC_ITT_CAMERA) {
                        n = buflen >= 15 ? buffer[14] : 0;
                        len = 15;

                } else if (type == UVC_ITT_MEDIA_TRANSPORT_INPUT) {
                        n = buflen >= 9 ? buffer[8] : 0;
                        p = buflen >= 10 + n ? buffer[9+n] : 0;
                        len = 10;
                }

                if (buflen < len + n + p) {
                        uvc_trace(UVC_TRACE_DESCR, "device %d videocontrol "
                                "interface %d INPUT_TERMINAL error\n",
                                udev->devnum, alts->desc.bInterfaceNumber);
                        return -EINVAL;
                }

                term = kzalloc(sizeof *term + n + p, GFP_KERNEL);
                if (term == NULL)
                        return -ENOMEM;

                term->id = buffer[3];
                term->type = type | UVC_TERM_INPUT;

                if (UVC_ENTITY_TYPE(term) == UVC_ITT_CAMERA) {
                        term->camera.bControlSize = n;
                        term->camera.bmControls = (__u8 *)term + sizeof *term;
                        term->camera.wObjectiveFocalLengthMin =
                                get_unaligned_le16(&buffer[8]);
                        term->camera.wObjectiveFocalLengthMax =
                                get_unaligned_le16(&buffer[10]);
                        term->camera.wOcularFocalLength =
                                get_unaligned_le16(&buffer[12]);
                        memcpy(term->camera.bmControls, &buffer[15], n);
                } else if (UVC_ENTITY_TYPE(term) ==
                           UVC_ITT_MEDIA_TRANSPORT_INPUT) {
                        term->media.bControlSize = n;
                        term->media.bmControls = (__u8 *)term + sizeof *term;
                        term->media.bTransportModeSize = p;
                        term->media.bmTransportModes = (__u8 *)term
                                                     + sizeof *term + n;
                        memcpy(term->media.bmControls, &buffer[9], n);
                        memcpy(term->media.bmTransportModes, &buffer[10+n], p);
                }

                if (buffer[7] != 0)
                        usb_string(udev, buffer[7], term->name,
                                   sizeof term->name);
                else if (UVC_ENTITY_TYPE(term) == UVC_ITT_CAMERA)
                        sprintf(term->name, "Camera %u", buffer[3]);
                else if (UVC_ENTITY_TYPE(term) == UVC_ITT_MEDIA_TRANSPORT_INPUT)
                        sprintf(term->name, "Media %u", buffer[3]);
                else
                        sprintf(term->name, "Input %u", buffer[3]);

                list_add_tail(&term->list, &dev->entities);
                break;

        case UVC_VC_OUTPUT_TERMINAL:
                if (buflen < 9) {
                        uvc_trace(UVC_TRACE_DESCR, "device %d videocontrol "
                                "interface %d OUTPUT_TERMINAL error\n",
                                udev->devnum, alts->desc.bInterfaceNumber);
                        return -EINVAL;
                }

                /* Make sure the terminal type MSB is not null, otherwise it
                 * could be confused with a unit.
                 */
                type = get_unaligned_le16(&buffer[4]);
                if ((type & 0xff00) == 0) {
                        uvc_trace(UVC_TRACE_DESCR, "device %d videocontrol "
                                "interface %d OUTPUT_TERMINAL %d has invalid "
                                "type 0x%04x, skipping\n", udev->devnum,
                                alts->desc.bInterfaceNumber, buffer[3], type);
                        return 0;
                }

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

                term->id = buffer[3];
                term->type = type | UVC_TERM_OUTPUT;
                term->output.bSourceID = buffer[7];

                if (buffer[8] != 0)
                        usb_string(udev, buffer[8], term->name,
                                   sizeof term->name);
                else
                        sprintf(term->name, "Output %u", buffer[3]);

                list_add_tail(&term->list, &dev->entities);
                break;

        case UVC_VC_SELECTOR_UNIT:
                p = buflen >= 5 ? buffer[4] : 0;

                if (buflen < 5 || buflen < 6 + p) {
                        uvc_trace(UVC_TRACE_DESCR, "device %d videocontrol "
                                "interface %d SELECTOR_UNIT error\n",
                                udev->devnum, alts->desc.bInterfaceNumber);
                        return -EINVAL;
                }

                unit = kzalloc(sizeof *unit + p, GFP_KERNEL);
                if (unit == NULL)
                        return -ENOMEM;

                unit->id = buffer[3];
                unit->type = buffer[2];
                unit->selector.bNrInPins = buffer[4];
                unit->selector.baSourceID = (__u8 *)unit + sizeof *unit;
                memcpy(unit->selector.baSourceID, &buffer[5], p);

                if (buffer[5+p] != 0)
                        usb_string(udev, buffer[5+p], unit->name,
                                   sizeof unit->name);
                else
                        sprintf(unit->name, "Selector %u", buffer[3]);

                list_add_tail(&unit->list, &dev->entities);
                break;

        case UVC_VC_PROCESSING_UNIT:
                n = buflen >= 8 ? buffer[7] : 0;
                p = dev->uvc_version >= 0x0110 ? 10 : 9;

                if (buflen < p + n) {
                        uvc_trace(UVC_TRACE_DESCR, "device %d videocontrol "
                                "interface %d PROCESSING_UNIT error\n",
                                udev->devnum, alts->desc.bInterfaceNumber);
                        return -EINVAL;
                }

                unit = kzalloc(sizeof *unit + n, GFP_KERNEL);
                if (unit == NULL)
                        return -ENOMEM;

                unit->id = buffer[3];
                unit->type = buffer[2];
                unit->processing.bSourceID = buffer[4];
                unit->processing.wMaxMultiplier =
                        get_unaligned_le16(&buffer[5]);
                unit->processing.bControlSize = buffer[7];
                unit->processing.bmControls = (__u8 *)unit + sizeof *unit;
                memcpy(unit->processing.bmControls, &buffer[8], n);
                if (dev->uvc_version >= 0x0110)
                        unit->processing.bmVideoStandards = buffer[9+n];

                if (buffer[8+n] != 0)
                        usb_string(udev, buffer[8+n], unit->name,
                                   sizeof unit->name);
                else
                        sprintf(unit->name, "Processing %u", buffer[3]);

                list_add_tail(&unit->list, &dev->entities);
                break;

        case UVC_VC_EXTENSION_UNIT:
                p = buflen >= 22 ? buffer[21] : 0;
                n = buflen >= 24 + p ? buffer[22+p] : 0;

                if (buflen < 24 + p + n) {
                        uvc_trace(UVC_TRACE_DESCR, "device %d videocontrol "
                                "interface %d EXTENSION_UNIT error\n",
                                udev->devnum, alts->desc.bInterfaceNumber);
                        return -EINVAL;
                }

                unit = kzalloc(sizeof *unit + p + n, GFP_KERNEL);
                if (unit == NULL)
                        return -ENOMEM;

                unit->id = buffer[3];
                unit->type = buffer[2];
                memcpy(unit->extension.guidExtensionCode, &buffer[4], 16);
                unit->extension.bNumControls = buffer[20];
                unit->extension.bNrInPins = get_unaligned_le16(&buffer[21]);
                unit->extension.baSourceID = (__u8 *)unit + sizeof *unit;
                memcpy(unit->extension.baSourceID, &buffer[22], p);
                unit->extension.bControlSize = buffer[22+p];
                unit->extension.bmControls = (__u8 *)unit + sizeof *unit + p;
                memcpy(unit->extension.bmControls, &buffer[23+p], n);

                if (buffer[23+p+n] != 0)
                        usb_string(udev, buffer[23+p+n], unit->name,
                                   sizeof unit->name);
                else
                        sprintf(unit->name, "Extension %u", buffer[3]);

                list_add_tail(&unit->list, &dev->entities);
                break;

        default:
                uvc_trace(UVC_TRACE_DESCR, "Found an unknown CS_INTERFACE "
                        "descriptor (%u)\n", buffer[2]);
                break;
        }

        return 0;
}

static int uvc_parse_control(struct uvc_device *dev)
{
        struct usb_host_interface *alts = dev->intf->cur_altsetting;
        unsigned char *buffer = alts->extra;
        int buflen = alts->extralen;
        int ret;

        /* Parse the default alternate setting only, as the UVC specification
         * defines a single alternate setting, the default alternate setting
         * zero.
         */

        while (buflen > 2) {
                if (uvc_parse_vendor_control(dev, buffer, buflen) ||
                    buffer[1] != USB_DT_CS_INTERFACE)
                        goto next_descriptor;

                if ((ret = uvc_parse_standard_control(dev, buffer, buflen)) < 0)
                        return ret;

next_descriptor:
                buflen -= buffer[0];
                buffer += buffer[0];
        }

        /* Check if the optional status endpoint is present. Built-in iSight
         * webcams have an interrupt endpoint but spit proprietary data that
         * don't conform to the UVC status endpoint messages. Don't try to
         * handle the interrupt endpoint for those cameras.
         */
        if (alts->desc.bNumEndpoints == 1 &&
            !(dev->quirks & UVC_QUIRK_BUILTIN_ISIGHT)) {
                struct usb_host_endpoint *ep = &alts->endpoint[0];
                struct usb_endpoint_descriptor *desc = &ep->desc;

                if (usb_endpoint_is_int_in(desc) &&
                    le16_to_cpu(desc->wMaxPacketSize) >= 8 &&
                    desc->bInterval != 0) {
                        uvc_trace(UVC_TRACE_DESCR, "Found a Status endpoint "
                                "(addr %02x).\n", desc->bEndpointAddress);
                        dev->int_ep = ep;
                }
        }

        return 0;
}

/* ------------------------------------------------------------------------
 * UVC device scan
 */

/*
 * Scan the UVC descriptors to locate a chain starting at an Output Terminal
 * and containing the following units:
 *
 * - one or more Output Terminals (USB Streaming or Display)
 * - zero or one Processing Unit
 * - zero, one or more single-input Selector Units
 * - zero or one multiple-input Selector Units, provided all inputs are
 *   connected to input terminals
 * - zero, one or mode single-input Extension Units
 * - one or more Input Terminals (Camera, External or USB Streaming)
 *
 * The terminal and units must match on of the following structures:
 *
 * ITT_*(0) -> +---------+    +---------+    +---------+ -> TT_STREAMING(0)
 * ...         | SU{0,1} | -> | PU{0,1} | -> | XU{0,n} |    ...
 * ITT_*(n) -> +---------+    +---------+    +---------+ -> TT_STREAMING(n)
 *
 *                 +---------+    +---------+ -> OTT_*(0)
 * TT_STREAMING -> | PU{0,1} | -> | XU{0,n} |    ...
 *                 +---------+    +---------+ -> OTT_*(n)
 *
 * The Processing Unit and Extension Units can be in any order. Additional
 * Extension Units connected to the main chain as single-unit branches are
 * also supported. Single-input Selector Units are ignored.
 */
static int uvc_scan_chain_entity(struct uvc_video_chain *chain,
        struct uvc_entity *entity)
{
        switch (UVC_ENTITY_TYPE(entity)) {
        case UVC_VC_EXTENSION_UNIT:
                if (uvc_trace_param & UVC_TRACE_PROBE)
                        printk(" <- XU %d", entity->id);

                if (entity->extension.bNrInPins != 1) {
                        uvc_trace(UVC_TRACE_DESCR, "Extension unit %d has more "
                                "than 1 input pin.\n", entity->id);
                        return -1;
                }

                list_add_tail(&entity->chain, &chain->extensions);
                break;

        case UVC_VC_PROCESSING_UNIT:
                if (uvc_trace_param & UVC_TRACE_PROBE)
                        printk(" <- PU %d", entity->id);

                if (chain->processing != NULL) {
                        uvc_trace(UVC_TRACE_DESCR, "Found multiple "
                                "Processing Units in chain.\n");
                        return -1;
                }

                chain->processing = entity;
                break;

        case UVC_VC_SELECTOR_UNIT:
                if (uvc_trace_param & UVC_TRACE_PROBE)
                        printk(" <- SU %d", entity->id);

                /* Single-input selector units are ignored. */
                if (entity->selector.bNrInPins == 1)
                        break;

                if (chain->selector != NULL) {
                        uvc_trace(UVC_TRACE_DESCR, "Found multiple Selector "
                                "Units in chain.\n");
                        return -1;
                }

                chain->selector = entity;
                break;

        case UVC_ITT_VENDOR_SPECIFIC:
        case UVC_ITT_CAMERA:
        case UVC_ITT_MEDIA_TRANSPORT_INPUT:
                if (uvc_trace_param & UVC_TRACE_PROBE)
                        printk(" <- IT %d\n", entity->id);

                list_add_tail(&entity->chain, &chain->iterms);
                break;

        case UVC_TT_STREAMING:
                if (uvc_trace_param & UVC_TRACE_PROBE)
                        printk(" <- IT %d\n", entity->id);

                if (!UVC_ENTITY_IS_ITERM(entity)) {
                        uvc_trace(UVC_TRACE_DESCR, "Unsupported input "
                                "terminal %u.\n", entity->id);
                        return -1;
                }

                list_add_tail(&entity->chain, &chain->iterms);
                break;

        default:
                uvc_trace(UVC_TRACE_DESCR, "Unsupported entity type "
                        "0x%04x found in chain.\n", UVC_ENTITY_TYPE(entity));
                return -1;
        }

        return 0;
}

static int uvc_scan_chain_forward(struct uvc_video_chain *chain,
        struct uvc_entity *entity, struct uvc_entity *prev)
{
        struct uvc_entity *forward;
        int found;

        /* Forward scan */
        forward = NULL;
        found = 0;

        while (1) {
                forward = uvc_entity_by_reference(chain->dev, entity->id,
                        forward);
                if (forward == NULL)
                        break;
                if (forward == prev)
                        continue;

                switch (UVC_ENTITY_TYPE(forward)) {
                case UVC_VC_EXTENSION_UNIT:
                        if (forward->extension.bNrInPins != 1) {
                                uvc_trace(UVC_TRACE_DESCR, "Extension unit %d "
                                          "has more than 1 input pin.\n",
                                          entity->id);
                                return -EINVAL;
                        }

                        list_add_tail(&forward->chain, &chain->extensions);
                        if (uvc_trace_param & UVC_TRACE_PROBE) {
                                if (!found)
                                        printk(" (->");

                                printk(" XU %d", forward->id);
                                found = 1;
                        }
                        break;

                case UVC_OTT_VENDOR_SPECIFIC:
                case UVC_OTT_DISPLAY:
                case UVC_OTT_MEDIA_TRANSPORT_OUTPUT:
                case UVC_TT_STREAMING:
                        if (UVC_ENTITY_IS_ITERM(forward)) {
                                uvc_trace(UVC_TRACE_DESCR, "Unsupported input "
                                        "terminal %u.\n", forward->id);
                                return -EINVAL;
                        }

                        list_add_tail(&forward->chain, &chain->oterms);
                        if (uvc_trace_param & UVC_TRACE_PROBE) {
                                if (!found)
                                        printk(" (->");

                                printk(" OT %d", forward->id);
                                found = 1;
                        }
                        break;
                }
        }
        if (found)
                printk(")");

        return 0;
}

static int uvc_scan_chain_backward(struct uvc_video_chain *chain,
        struct uvc_entity *entity)
{
        struct uvc_entity *term;
        int id = -1, i;

        switch (UVC_ENTITY_TYPE(entity)) {
        case UVC_VC_EXTENSION_UNIT:
                id = entity->extension.baSourceID[0];
                break;

        case UVC_VC_PROCESSING_UNIT:
                id = entity->processing.bSourceID;
                break;

        case UVC_VC_SELECTOR_UNIT:
                /* Single-input selector units are ignored. */
                if (entity->selector.bNrInPins == 1) {
                        id = entity->selector.baSourceID[0];
                        break;
                }

                if (uvc_trace_param & UVC_TRACE_PROBE)
                        printk(" <- IT");

                chain->selector = entity;
                for (i = 0; i < entity->selector.bNrInPins; ++i) {
                        id = entity->selector.baSourceID[i];
                        term = uvc_entity_by_id(chain->dev, id);
                        if (term == NULL || !UVC_ENTITY_IS_ITERM(term)) {
                                uvc_trace(UVC_TRACE_DESCR, "Selector unit %d "
                                        "input %d isn't connected to an "
                                        "input terminal\n", entity->id, i);
                                return -1;
                        }

                        if (uvc_trace_param & UVC_TRACE_PROBE)
                                printk(" %d", term->id);

                        list_add_tail(&term->chain, &chain->iterms);
                        uvc_scan_chain_forward(chain, term, entity);
                }

                if (uvc_trace_param & UVC_TRACE_PROBE)
                        printk("\n");

                id = 0;
                break;
        }

        return id;
}

static int uvc_scan_chain(struct uvc_video_chain *chain,
                          struct uvc_entity *oterm)
{
        struct uvc_entity *entity, *prev;
        int id;

        entity = oterm;
        list_add_tail(&entity->chain, &chain->oterms);
        uvc_trace(UVC_TRACE_PROBE, "Scanning UVC chain: OT %d", entity->id);

        id = entity->output.bSourceID;
        while (id != 0) {
                prev = entity;
                entity = uvc_entity_by_id(chain->dev, id);
                if (entity == NULL) {
                        uvc_trace(UVC_TRACE_DESCR, "Found reference to "
                                "unknown entity %d.\n", id);
                        return -EINVAL;
                }

                if (entity->chain.next || entity->chain.prev) {
                        uvc_trace(UVC_TRACE_DESCR, "Found reference to "
                                "entity %d already in chain.\n", id);
                        return -EINVAL;
                }

                /* Process entity */
                if (uvc_scan_chain_entity(chain, entity) < 0)
                        return -EINVAL;

                /* Forward scan */
                if (uvc_scan_chain_forward(chain, entity, prev) < 0)
                        return -EINVAL;

                /* Stop when a terminal is found. */
                if (UVC_ENTITY_IS_TERM(entity))
                        break;

                /* Backward scan */
                id = uvc_scan_chain_backward(chain, entity);
                if (id < 0)
                        return id;
        }

        return 0;
}

static unsigned int uvc_print_terms(struct list_head *terms, char *buffer)
{
        struct uvc_entity *term;
        unsigned int nterms = 0;
        char *p = buffer;

        list_for_each_entry(term, terms, chain) {
                p += sprintf(p, "%u", term->id);
                if (term->chain.next != terms) {
                        p += sprintf(p, ",");
                        if (++nterms >= 4) {
                                p += sprintf(p, "...");
                                break;
                        }
                }
        }

        return p - buffer;
}

static const char *uvc_print_chain(struct uvc_video_chain *chain)
{
        static char buffer[43];
        char *p = buffer;

        p += uvc_print_terms(&chain->iterms, p);
        p += sprintf(p, " -> ");
        uvc_print_terms(&chain->oterms, p);

        return buffer;
}

/*
 * Scan the device for video chains and register video devices.
 *
 * Chains are scanned starting at their output terminals and walked backwards.
 */
static int uvc_scan_device(struct uvc_device *dev)
{
        struct uvc_video_chain *chain;
        struct uvc_entity *term;

        list_for_each_entry(term, &dev->entities, list) {
                if (!UVC_ENTITY_IS_OTERM(term))
                        continue;

                /* If the terminal is already included in a chain, skip it.
                 * This can happen for chains that have multiple output
                 * terminals, where all output terminals beside the first one
                 * will be inserted in the chain in forward scans.
                 */
                if (term->chain.next || term->chain.prev)
                        continue;

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

                INIT_LIST_HEAD(&chain->iterms);
                INIT_LIST_HEAD(&chain->oterms);
                INIT_LIST_HEAD(&chain->extensions);
                mutex_init(&chain->ctrl_mutex);
                chain->dev = dev;

                if (uvc_scan_chain(chain, term) < 0) {
                        kfree(chain);
                        continue;
                }

                uvc_trace(UVC_TRACE_PROBE, "Found a valid video chain (%s).\n",
                          uvc_print_chain(chain));

                list_add_tail(&chain->list, &dev->chains);
        }

        if (list_empty(&dev->chains)) {
                uvc_printk(KERN_INFO, "No valid video chain found.\n");
                return -1;
        }

        return 0;
}

/* ------------------------------------------------------------------------
 * Video device registration and unregistration
 */

/*
 * Unregister the video devices.
 */
static void uvc_unregister_video(struct uvc_device *dev)
{
        struct uvc_streaming *stream;

        list_for_each_entry(stream, &dev->streams, list) {
                if (stream->vdev == NULL)
                        continue;

                if (stream->vdev->minor == -1)
                        video_device_release(stream->vdev);
                else
                        video_unregister_device(stream->vdev);
                stream->vdev = NULL;
        }
}

static int uvc_register_video(struct uvc_device *dev,
                struct uvc_streaming *stream)
{
        struct video_device *vdev;
        int ret;

        /* Initialize the streaming interface with default streaming
         * parameters.
         */
        ret = uvc_video_init(stream);
        if (ret < 0) {
                uvc_printk(KERN_ERR, "Failed to initialize the device "
                        "(%d).\n", ret);
                return ret;
        }

        /* Register the device with V4L. */
        vdev = video_device_alloc();
        if (vdev == NULL) {
                uvc_printk(KERN_ERR, "Failed to allocate video device (%d).\n",
                           ret);
                return -ENOMEM;
        }

        /* We already hold a reference to dev->udev. The video device will be
         * unregistered before the reference is released, so we don't need to
         * get another one.
         */
        vdev->parent = &dev->intf->dev;
        vdev->minor = -1;
        vdev->fops = &uvc_fops;
        vdev->release = video_device_release;
        strlcpy(vdev->name, dev->name, sizeof vdev->name);

        /* Set the driver data before calling video_register_device, otherwise
         * uvc_v4l2_open might race us.
         */
        stream->vdev = vdev;
        video_set_drvdata(vdev, stream);

        ret = video_register_device(vdev, VFL_TYPE_GRABBER, -1);
        if (ret < 0) {
                uvc_printk(KERN_ERR, "Failed to register video device (%d).\n",
                           ret);
                stream->vdev = NULL;
                video_device_release(vdev);
                return ret;
        }

        return 0;
}

/*
 * Register all video devices in all chains.
 */
static int uvc_register_terms(struct uvc_device *dev,
        struct uvc_video_chain *chain, struct list_head *terms)
{
        struct uvc_streaming *stream;
        struct uvc_entity *term;
        int ret;

        list_for_each_entry(term, terms, chain) {
                if (UVC_ENTITY_TYPE(term) != UVC_TT_STREAMING)
                        continue;

                stream = uvc_stream_by_id(dev, term->id);
                if (stream == NULL) {
                        uvc_printk(KERN_INFO, "No streaming interface found "
                                   "for terminal %u.", term->id);
                        continue;
                }

                stream->chain = chain;
                ret = uvc_register_video(dev, stream);
                if (ret < 0)
                        return ret;
        }

        return 0;
}

static int uvc_register_chains(struct uvc_device *dev)
{
        struct uvc_video_chain *chain;
        int ret;

        list_for_each_entry(chain, &dev->chains, list) {
                ret = uvc_register_terms(dev, chain, &chain->iterms);
                if (ret < 0)
                        return ret;

                ret = uvc_register_terms(dev, chain, &chain->oterms);
                if (ret < 0)
                        return ret;
        }

        return 0;
}

/* ------------------------------------------------------------------------
 * USB probe, disconnect, suspend and resume
 */

/*
 * Delete the UVC device.
 *
 * Called by the kernel when the last reference to the uvc_device structure
 * is released.
 *
 * Unregistering the video devices is done here because every opened instance
 * must be closed before the device can be unregistered. An alternative would
 * have been to use another reference count for uvc_v4l2_open/uvc_release, and
 * unregister the video devices on disconnect when that reference count drops
 * to zero.
 *
 * As this function is called after or during disconnect(), all URBs have
 * already been canceled by the USB core. There is no need to kill the
 * interrupt URB manually.
 */
void uvc_delete(struct kref *kref)
{
        struct uvc_device *dev = container_of(kref, struct uvc_device, kref);
        struct list_head *p, *n;

        /* Unregister the video devices. */
        uvc_unregister_video(dev);
        usb_put_intf(dev->intf);
        usb_put_dev(dev->udev);

        uvc_status_cleanup(dev);
        uvc_ctrl_cleanup_device(dev);

        list_for_each_safe(p, n, &dev->chains) {
                struct uvc_video_chain *chain;
                chain = list_entry(p, struct uvc_video_chain, list);
                kfree(chain);
        }

        list_for_each_safe(p, n, &dev->entities) {
                struct uvc_entity *entity;
                entity = list_entry(p, struct uvc_entity, list);
                kfree(entity);
        }

        list_for_each_safe(p, n, &dev->streams) {
                struct uvc_streaming *streaming;
                streaming = list_entry(p, struct uvc_streaming, list);
                usb_driver_release_interface(&uvc_driver.driver,
                        streaming->intf);
                usb_put_intf(streaming->intf);
                kfree(streaming->format);
                kfree(streaming->header.bmaControls);
                kfree(streaming);
        }

        kfree(dev);
}

static int uvc_probe(struct usb_interface *intf,
                     const struct usb_device_id *id)
{
        struct usb_device *udev = interface_to_usbdev(intf);
        struct uvc_device *dev;
        int ret;

        if (id->idVendor && id->idProduct)
                uvc_trace(UVC_TRACE_PROBE, "Probing known UVC device %s "
                                "(%04x:%04x)\n", udev->devpath, id->idVendor,
                                id->idProduct);
        else
                uvc_trace(UVC_TRACE_PROBE, "Probing generic UVC device %s\n",
                                udev->devpath);

        /* Allocate memory for the device and initialize it. */
        if ((dev = kzalloc(sizeof *dev, GFP_KERNEL)) == NULL)
                return -ENOMEM;

        INIT_LIST_HEAD(&dev->entities);
        INIT_LIST_HEAD(&dev->chains);
        INIT_LIST_HEAD(&dev->streams);
        kref_init(&dev->kref);
        atomic_set(&dev->users, 0);

        dev->udev = usb_get_dev(udev);
        dev->intf = usb_get_intf(intf);
        dev->intfnum = intf->cur_altsetting->desc.bInterfaceNumber;
        dev->quirks = id->driver_info | uvc_quirks_param;

        if (udev->product != NULL)
                strlcpy(dev->name, udev->product, sizeof dev->name);
        else
                snprintf(dev->name, sizeof dev->name,
                        "UVC Camera (%04x:%04x)",
                        le16_to_cpu(udev->descriptor.idVendor),
                        le16_to_cpu(udev->descriptor.idProduct));

        /* Parse the Video Class control descriptor. */
        if (uvc_parse_control(dev) < 0) {
                uvc_trace(UVC_TRACE_PROBE, "Unable to parse UVC "
                        "descriptors.\n");
                goto error;
        }

        uvc_printk(KERN_INFO, "Found UVC %u.%02x device %s (%04x:%04x)\n",
                dev->uvc_version >> 8, dev->uvc_version & 0xff,
                udev->product ? udev->product : "<unnamed>",
                le16_to_cpu(udev->descriptor.idVendor),
                le16_to_cpu(udev->descriptor.idProduct));

        if (uvc_quirks_param != 0) {
                uvc_printk(KERN_INFO, "Forcing device quirks 0x%x by module "
                        "parameter for testing purpose.\n", uvc_quirks_param);
                uvc_printk(KERN_INFO, "Please report required quirks to the "
                        "linux-uvc-devel mailing list.\n");
        }

        /* Initialize controls. */
        if (uvc_ctrl_init_device(dev) < 0)
                goto error;

        /* Scan the device for video chains. */
        if (uvc_scan_device(dev) < 0)
                goto error;

        /* Register video devices. */
        if (uvc_register_chains(dev) < 0)
                goto error;

        /* Save our data pointer in the interface data. */
        usb_set_intfdata(intf, dev);

        /* Initialize the interrupt URB. */
        if ((ret = uvc_status_init(dev)) < 0) {
                uvc_printk(KERN_INFO, "Unable to initialize the status "
                        "endpoint (%d), status interrupt will not be "
                        "supported.\n", ret);
        }

        uvc_trace(UVC_TRACE_PROBE, "UVC device initialized.\n");
        return 0;

error:
        kref_put(&dev->kref, uvc_delete);
        return -ENODEV;
}

static void uvc_disconnect(struct usb_interface *intf)
{
        struct uvc_device *dev = usb_get_intfdata(intf);

        /* Set the USB interface data to NULL. This can be done outside the
         * lock, as there's no other reader.
         */
        usb_set_intfdata(intf, NULL);

        if (intf->cur_altsetting->desc.bInterfaceSubClass ==
            UVC_SC_VIDEOSTREAMING)
                return;

        /* uvc_v4l2_open() might race uvc_disconnect(). A static driver-wide
         * lock is needed to prevent uvc_disconnect from releasing its
         * reference to the uvc_device instance after uvc_v4l2_open() received
         * the pointer to the device (video_devdata) but before it got the
         * chance to increase the reference count (kref_get).
         *
         * Note that the reference can't be released with the lock held,
         * otherwise a AB-BA deadlock can occur with videodev_lock that
         * videodev acquires in videodev_open() and video_unregister_device().
         */
        mutex_lock(&uvc_driver.open_mutex);
        dev->state |= UVC_DEV_DISCONNECTED;
        mutex_unlock(&uvc_driver.open_mutex);

        kref_put(&dev->kref, uvc_delete);
}

static int uvc_suspend(struct usb_interface *intf, pm_message_t message)
{
        struct uvc_device *dev = usb_get_intfdata(intf);
        struct uvc_streaming *stream;

        uvc_trace(UVC_TRACE_SUSPEND, "Suspending interface %u\n",
                intf->cur_altsetting->desc.bInterfaceNumber);

        /* Controls are cached on the fly so they don't need to be saved. */
        if (intf->cur_altsetting->desc.bInterfaceSubClass ==
            UVC_SC_VIDEOCONTROL)
                return uvc_status_suspend(dev);

        list_for_each_entry(stream, &dev->streams, list) {
                if (stream->intf == intf)
                        return uvc_video_suspend(stream);
        }

        uvc_trace(UVC_TRACE_SUSPEND, "Suspend: video streaming USB interface "
                        "mismatch.\n");
        return -EINVAL;
}

static int __uvc_resume(struct usb_interface *intf, int reset)
{
        struct uvc_device *dev = usb_get_intfdata(intf);
        struct uvc_streaming *stream;

        uvc_trace(UVC_TRACE_SUSPEND, "Resuming interface %u\n",
                intf->cur_altsetting->desc.bInterfaceNumber);

        if (intf->cur_altsetting->desc.bInterfaceSubClass ==
            UVC_SC_VIDEOCONTROL) {
                if (reset) {
                        int ret = uvc_ctrl_resume_device(dev);

                        if (ret < 0)
                                return ret;
                }

                return uvc_status_resume(dev);
        }

        list_for_each_entry(stream, &dev->streams, list) {
                if (stream->intf == intf)
                        return uvc_video_resume(stream);
        }

        uvc_trace(UVC_TRACE_SUSPEND, "Resume: video streaming USB interface "
                        "mismatch.\n");
        return -EINVAL;
}

static int uvc_resume(struct usb_interface *intf)
{
        return __uvc_resume(intf, 0);
}

static int uvc_reset_resume(struct usb_interface *intf)
{
        return __uvc_resume(intf, 1);
}

/* ------------------------------------------------------------------------
 * Driver initialization and cleanup
 */

/*
 * The Logitech cameras listed below have their interface class set to
 * VENDOR_SPEC because they don't announce themselves as UVC devices, even
 * though they are compliant.
 */
static struct usb_device_id uvc_ids[] = {
        /* Microsoft Lifecam NX-6000 */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x045e,
          .idProduct            = 0x00f8,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_PROBE_MINMAX },
        /* Microsoft Lifecam VX-7000 */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x045e,
          .idProduct            = 0x0723,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_PROBE_MINMAX },
        /* Logitech Quickcam Fusion */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x046d,
          .idProduct            = 0x08c1,
          .bInterfaceClass      = USB_CLASS_VENDOR_SPEC,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0 },
        /* Logitech Quickcam Orbit MP */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x046d,
          .idProduct            = 0x08c2,
          .bInterfaceClass      = USB_CLASS_VENDOR_SPEC,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0 },
        /* Logitech Quickcam Pro for Notebook */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x046d,
          .idProduct            = 0x08c3,
          .bInterfaceClass      = USB_CLASS_VENDOR_SPEC,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0 },
        /* Logitech Quickcam Pro 5000 */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x046d,
          .idProduct            = 0x08c5,
          .bInterfaceClass      = USB_CLASS_VENDOR_SPEC,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0 },
        /* Logitech Quickcam OEM Dell Notebook */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x046d,
          .idProduct            = 0x08c6,
          .bInterfaceClass      = USB_CLASS_VENDOR_SPEC,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0 },
        /* Logitech Quickcam OEM Cisco VT Camera II */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x046d,
          .idProduct            = 0x08c7,
          .bInterfaceClass      = USB_CLASS_VENDOR_SPEC,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0 },
        /* Alcor Micro AU3820 (Future Boy PC USB Webcam) */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x058f,
          .idProduct            = 0x3820,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_PROBE_MINMAX },
        /* Apple Built-In iSight */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x05ac,
          .idProduct            = 0x8501,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_PROBE_MINMAX
                                | UVC_QUIRK_BUILTIN_ISIGHT },
        /* Genesys Logic USB 2.0 PC Camera */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x05e3,
          .idProduct            = 0x0505,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_STREAM_NO_FID },
        /* ViMicro Vega */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x0ac8,
          .idProduct            = 0x332d,

          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_FIX_BANDWIDTH },
        /* ViMicro - Minoru3D */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x0ac8,
          .idProduct            = 0x3410,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_FIX_BANDWIDTH },
        /* ViMicro Venus - Minoru3D */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x0ac8,
          .idProduct            = 0x3420,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_FIX_BANDWIDTH },
        /* MT6227 */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x0e8d,
          .idProduct            = 0x0004,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_PROBE_MINMAX
                                | UVC_QUIRK_PROBE_DEF },
        /* Syntek (HP Spartan) */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x174f,
          .idProduct            = 0x5212,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_STREAM_NO_FID },
        /* Syntek (Samsung Q310) */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x174f,
          .idProduct            = 0x5931,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_STREAM_NO_FID },
        /* Syntek (Asus F9SG) */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x174f,
          .idProduct            = 0x8a31,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_STREAM_NO_FID },
        /* Syntek (Asus U3S) */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x174f,
          .idProduct            = 0x8a33,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_STREAM_NO_FID },
        /* Syntek (JAOtech Smart Terminal) */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x174f,
          .idProduct            = 0x8a34,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_STREAM_NO_FID },
        /* Lenovo Thinkpad SL400/SL500 */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x17ef,
          .idProduct            = 0x480b,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_STREAM_NO_FID },
        /* Aveo Technology USB 2.0 Camera */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x1871,
          .idProduct            = 0x0306,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_PROBE_MINMAX
                                | UVC_QUIRK_PROBE_EXTRAFIELDS },
        /* Ecamm Pico iMage */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x18cd,
          .idProduct            = 0xcafe,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_PROBE_EXTRAFIELDS },
        /* FSC WebCam V30S */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x18ec,
          .idProduct            = 0x3288,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_PROBE_MINMAX },
        /* Bodelin ProScopeHR */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_DEV_HI
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x19ab,
          .idProduct            = 0x1000,
          .bcdDevice_hi         = 0x0126,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_STATUS_INTERVAL },
        /* SiGma Micro USB Web Camera */
        { .match_flags          = USB_DEVICE_ID_MATCH_DEVICE
                                | USB_DEVICE_ID_MATCH_INT_INFO,
          .idVendor             = 0x1c4f,
          .idProduct            = 0x3000,
          .bInterfaceClass      = USB_CLASS_VIDEO,
          .bInterfaceSubClass   = 1,
          .bInterfaceProtocol   = 0,
          .driver_info          = UVC_QUIRK_PROBE_MINMAX
                                | UVC_QUIRK_IGNORE_SELECTOR_UNIT },
        /* Generic USB Video Class */
        { USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, 0) },
        {}
};

MODULE_DEVICE_TABLE(usb, uvc_ids);

struct uvc_driver uvc_driver = {
        .driver = {
                .name           = "uvcvideo",
                .probe          = uvc_probe,
                .disconnect     = uvc_disconnect,
                .suspend        = uvc_suspend,
                .resume         = uvc_resume,
                .reset_resume   = uvc_reset_resume,
                .id_table       = uvc_ids,
                .supports_autosuspend = 1,
        },
};

static int __init uvc_init(void)
{
        int result;

        INIT_LIST_HEAD(&uvc_driver.devices);
        INIT_LIST_HEAD(&uvc_driver.controls);
        mutex_init(&uvc_driver.open_mutex);
        mutex_init(&uvc_driver.ctrl_mutex);

        uvc_ctrl_init();

        result = usb_register(&uvc_driver.driver);
        if (result == 0)
                printk(KERN_INFO DRIVER_DESC " (" DRIVER_VERSION ")\n");
        return result;
}

static void __exit uvc_cleanup(void)
{
        usb_deregister(&uvc_driver.driver);
}

module_init(uvc_init);
module_exit(uvc_cleanup);

module_param_named(nodrop, uvc_no_drop_param, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(nodrop, "Don't drop incomplete frames");
module_param_named(quirks, uvc_quirks_param, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(quirks, "Forced device quirks");
module_param_named(trace, uvc_trace_param, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(trace, "Trace level bitmask");

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");
MODULE_VERSION(DRIVER_VERSION);