text: /*
   * Fushicai USBTV007 Video Grabber Driver
   *
   * Product web site:
   * http://www.fushicai.com/products_detail/&productId=d05449ee-b690-42f9-a661-aa7353894bed.html
   *
   * Following LWN articles were very useful in construction of this driver:
   * Video4Linux2 API series: http://lwn.net/Articles/203924/
   * videobuf2 API explanation: http://lwn.net/Articles/447435/
   * Thanks go to Jonathan Corbet for providing this quality documentation.
   * He is awesome.
   *
   * Copyright (c) 2013 Lubomir Rintel
   * All rights reserved.
   * No physical hardware was harmed running Windows during the
   * reverse-engineering activity
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions, and the following disclaimer,
   *    without modification.
   * 2. The name of the author may not be used to endorse or promote products
   *    derived from this software without specific prior written permission.
   *
   * Alternatively, this software may be distributed under the terms of the
   * GNU General Public License ("GPL").
   */
  
  #include <linux/init.h>
  #include <linux/list.h>
  #include <linux/module.h>
  #include <linux/slab.h>
  #include <linux/usb.h>
  #include <linux/version.h>
  #include <linux/videodev2.h>
  
  #include <media/v4l2-device.h>
  #include <media/v4l2-ioctl.h>
  #include <media/videobuf2-core.h>
  #include <media/videobuf2-vmalloc.h>
  
  /*
   ambi-tv stuff
  */
  #define AMBITV_PAL_HACK
  
  /* Hardware. */
  #define USBTV_VIDEO_ENDP       0x81
  #define USBTV_BASE             0xc000
  #define USBTV_REQUEST_REG      12
  
  /* Number of concurrent isochronous urbs submitted.
   * Higher numbers was seen to overly saturate the USB bus. */
  #define USBTV_ISOC_TRANSFERS   32
  #define USBTV_ISOC_PACKETS     8
  
  #define USBTV_WIDTH            720
  #ifdef AMBITV_PAL_HACK
  #define USBTV_HEIGHT           576
  #else
  #define USBTV_HEIGHT           480
  #endif
  
  #define USBTV_CHUNK_SIZE       256
  #define USBTV_CHUNK            240
  #define USBTV_CHUNKS           (USBTV_WIDTH * USBTV_HEIGHT \
                                         / 4 / USBTV_CHUNK)
  
  /* Chunk header. */
  #define USBTV_MAGIC_OK(chunk)  ((be32_to_cpu(chunk[0]) & 0xff000000) \
                                                         == 0x88000000)
  #define USBTV_FRAME_ID(chunk)  ((be32_to_cpu(chunk[0]) & 0x00ff0000) >> 16)
  #define USBTV_ODD(chunk)       ((be32_to_cpu(chunk[0]) & 0x0000f000) >> 15)
  #define USBTV_CHUNK_NO(chunk)  (be32_to_cpu(chunk[0]) & 0x00000fff)
  
  /* A single videobuf2 frame buffer. */
  struct usbtv_buf {
         struct vb2_buffer vb;
         struct list_head list;
  };
  
  /* Per-device structure. */
  struct usbtv {
         struct device *dev;
         struct usb_device *udev;
         struct v4l2_device v4l2_dev;
         struct video_device vdev;
         struct vb2_queue vb2q;
         struct mutex v4l2_lock;
         struct mutex vb2q_lock;
  
         /* List of videobuf2 buffers protected by a lock. */
         spinlock_t buflock;
         struct list_head bufs;
  
         /* Number of currently processed frame, useful find
          * out when a new one begins. */
         u32 frame_id;
         int chunks_done;
  
         int iso_size, iso_interval;
         unsigned int sequence;
         struct urb *isoc_urbs[USBTV_ISOC_TRANSFERS];
  };
  
  static int usbtv_setup_capture(struct usbtv *usbtv)
  {
         int ret;
         int pipe = usb_rcvctrlpipe(usbtv->udev, 0);
         int i;
         static const u16 protoregs[][2] = {
                 /* These seem to enable the device. */
                 { USBTV_BASE + 0x0008, 0x0001 },
                 { USBTV_BASE + 0x01d0, 0x00ff },
                 { USBTV_BASE + 0x01d9, 0x0002 },
  
                 /* These seem to influence color parameters, such as
                  * brightness, etc. */
                 { USBTV_BASE + 0x0239, 0x0040 },
                 { USBTV_BASE + 0x0240, 0x0000 },
                 { USBTV_BASE + 0x0241, 0x0000 },
                 { USBTV_BASE + 0x0242, 0x0002 },
                 { USBTV_BASE + 0x0243, 0x0080 },
                 { USBTV_BASE + 0x0244, 0x0012 },
                 { USBTV_BASE + 0x0245, 0x0090 },
                 { USBTV_BASE + 0x0246, 0x0000 },
  
                 { USBTV_BASE + 0x0278, 0x002d },
                 { USBTV_BASE + 0x0279, 0x000a },
                 { USBTV_BASE + 0x027a, 0x0032 },
                 
                 { 0xf890, 0x000c },
                 { 0xf894, 0x0086 },
  
                 { USBTV_BASE + 0x00ac, 0x00c0 },
                 { USBTV_BASE + 0x00ad, 0x0000 },
                 { USBTV_BASE + 0x00a2, 0x0012 },
                 { USBTV_BASE + 0x00a3, 0x00e0 },
                 { USBTV_BASE + 0x00a4, 0x0028 },
                 { USBTV_BASE + 0x00a5, 0x0082 },
                 { USBTV_BASE + 0x00a7, 0x0080 },
                 { USBTV_BASE + 0x0000, 0x0014 },
                 { USBTV_BASE + 0x0006, 0x0003 },
                 { USBTV_BASE + 0x0090, 0x0099 },
                 { USBTV_BASE + 0x0091, 0x0090 },
                 { USBTV_BASE + 0x0094, 0x0068 },
                 { USBTV_BASE + 0x0095, 0x0070 },
                 { USBTV_BASE + 0x009c, 0x0030 },
                 { USBTV_BASE + 0x009d, 0x00c0 },
                 { USBTV_BASE + 0x009e, 0x00e0 },
                 { USBTV_BASE + 0x0019, 0x0006 },
                 { USBTV_BASE + 0x008c, 0x00ba },
                 { USBTV_BASE + 0x0101, 0x00ff },
                 { USBTV_BASE + 0x010c, 0x00b3 },
                 { USBTV_BASE + 0x01b2, 0x0080 },
                 { USBTV_BASE + 0x01b4, 0x00a0 },
                 { USBTV_BASE + 0x014c, 0x00ff },
                 { USBTV_BASE + 0x014d, 0x00ca },
                 { USBTV_BASE + 0x0113, 0x0053 },
                 { USBTV_BASE + 0x0119, 0x008a },
                 { USBTV_BASE + 0x013c, 0x0003 },
                 { USBTV_BASE + 0x0150, 0x009c },
                 { USBTV_BASE + 0x0151, 0x0071 },
                 { USBTV_BASE + 0x0152, 0x00c6 },
                 { USBTV_BASE + 0x0153, 0x0084 },
                 { USBTV_BASE + 0x0154, 0x00bc },
                 { USBTV_BASE + 0x0155, 0x00a0 },
                 { USBTV_BASE + 0x0156, 0x00a0 },
                 { USBTV_BASE + 0x0157, 0x009c },
                 { USBTV_BASE + 0x0158, 0x001f },
                 { USBTV_BASE + 0x0159, 0x0006 },
                 { USBTV_BASE + 0x015d, 0x0000 },
  
                 { USBTV_BASE + 0x0284, 0x0088 },
                 { USBTV_BASE + 0x0003, 0x0004 },
  #ifndef AMBITV_PAL_HACK
                 { USBTV_BASE + 0x001a, 0x0079 },
  #else
                 { USBTV_BASE + 0x001a, 0x0068 },
  #endif
                 { USBTV_BASE + 0x0100, 0x00d3 },
  #ifndef AMBITV_PAL_HACK
                 { USBTV_BASE + 0x010e, 0x0068 },
                 { USBTV_BASE + 0x010f, 0x009c },
                 { USBTV_BASE + 0x0112, 0x00f0 },
  #else
                 { USBTV_BASE + 0x010e, 0x0072 },
                 { USBTV_BASE + 0x010f, 0x00a2 },
                 { USBTV_BASE + 0x0112, 0x00b0 },
  #endif
                 { USBTV_BASE + 0x0115, 0x0015 },
  #ifndef AMBITV_PAL_HACK
                 { USBTV_BASE + 0x0117, 0x0000 },
                 { USBTV_BASE + 0x0118, 0x00fc },
                 { USBTV_BASE + 0x012d, 0x0004 },
                 { USBTV_BASE + 0x012f, 0x0008 },
  #else
                 { USBTV_BASE + 0x0117, 0x0001 },
                 { USBTV_BASE + 0x0118, 0x002c },
                 { USBTV_BASE + 0x012d, 0x0010 },
                 { USBTV_BASE + 0x012f, 0x0020 },
  #endif
                 { USBTV_BASE + 0x0220, 0x002e },
                 { USBTV_BASE + 0x0225, 0x0008 },
                 { USBTV_BASE + 0x024e, 0x0002 },
  #ifndef AMBITV_PAL_HACK
                 { USBTV_BASE + 0x024f, 0x0001 },
                 { USBTV_BASE + 0x0254, 0x005f },
                 { USBTV_BASE + 0x025a, 0x0012 },
                 { USBTV_BASE + 0x025b, 0x0001 },
                 { USBTV_BASE + 0x0263, 0x001c },
                 { USBTV_BASE + 0x0266, 0x0011 },
                 { USBTV_BASE + 0x0267, 0x0005 },
  #else
                 { USBTV_BASE + 0x024f, 0x0002 },
                 { USBTV_BASE + 0x0254, 0x0059 },
                 { USBTV_BASE + 0x025a, 0x0016 },
                 { USBTV_BASE + 0x025b, 0x0035 },
                 { USBTV_BASE + 0x0263, 0x0017 },
                 { USBTV_BASE + 0x0266, 0x0016 },
                 { USBTV_BASE + 0x0267, 0x0036 },
  #endif
                 { USBTV_BASE + 0x024e, 0x0002 },
                 { USBTV_BASE + 0x024f, 0x0002 },
         };
  
         for (i = 0; i < ARRAY_SIZE(protoregs); i++) {
                 u16 index = protoregs[i][0];
                 u16 value = protoregs[i][1];
  
                 ret = usb_control_msg(usbtv->udev, pipe, USBTV_REQUEST_REG,
                         USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
                         value, index, NULL, 0, 0);
                 if (ret < 0)
                         return ret;
         }
  
         return 0;
  }
  
  /* Copy data from chunk into a frame buffer, deinterlacing the data
   * into every second line. Unfortunately, they don't align nicely into
   * 720 pixel lines, as the chunk is 240 words long, which is 480 pixels.
   * Therefore, we break down the chunk into two halves before copyting,
   * so that we can interleave a line if needed. */
  static void usbtv_chunk_to_vbuf(u32 *frame, u32 *src, int chunk_no, int odd)
  {
         int half;
  
         for (half = 0; half < 2; half++) {
                 int part_no = chunk_no * 2 + half;
                 int line = part_no / 3;
                 int part_index = (line * 2 + !odd) * 3 + (part_no % 3);
  
                 u32 *dst = &frame[part_index * USBTV_CHUNK/2];
                 memcpy(dst, src, USBTV_CHUNK/2 * sizeof(*src));
                 src += USBTV_CHUNK/2;
         }
  }
  
  
  /* Called for each 256-byte image chunk.
   * First word identifies the chunk, followed by 240 words of image
   * data and padding. */
  static void usbtv_image_chunk(struct usbtv *usbtv, u32 *chunk)
  {
         int frame_id, odd, chunk_no, chunk_no_orig;
         u32 *frame;
         struct usbtv_buf *buf;
         unsigned long flags;
  
         /* Ignore corrupted lines. */
         if (!USBTV_MAGIC_OK(chunk))
                 return;
         frame_id = USBTV_FRAME_ID(chunk);
         odd = USBTV_ODD(chunk);
         chunk_no = chunk_no_orig = USBTV_CHUNK_NO(chunk);
         
         if (chunk_no >= USBTV_CHUNKS)
                 return;
  
         /* Beginning of a frame. */
         if (chunk_no == 0) {
                 usbtv->frame_id = frame_id;
                 usbtv->chunks_done = 0;
         }
         
         if (usbtv->frame_id != frame_id)
                 return;
  
         spin_lock_irqsave(&usbtv->buflock, flags);
         if (list_empty(&usbtv->bufs)) {
                 /* No free buffers. Userspace likely too slow. */
                 spin_unlock_irqrestore(&usbtv->buflock, flags);
                 return;
         }
  
         /* First available buffer. */
         buf = list_first_entry(&usbtv->bufs, struct usbtv_buf, list);
         frame = vb2_plane_vaddr(&buf->vb, 0);
  
         /* Copy the chunk data. */
         usbtv_chunk_to_vbuf(frame, &chunk[1], chunk_no, odd);
         usbtv->chunks_done++;
  
         /* Last chunk in a frame, signalling an end */
         if (odd && chunk_no == USBTV_CHUNKS-1) {
                 int size = vb2_plane_size(&buf->vb, 0);
                 
                 enum vb2_buffer_state state = usbtv->chunks_done ==
                                                                USBTV_CHUNKS ?
                                                                VB2_BUF_STATE_DONE :
                                                                VB2_BUF_STATE_ERROR;
  
                 buf->vb.v4l2_buf.field = V4L2_FIELD_INTERLACED;
                 buf->vb.v4l2_buf.sequence = usbtv->sequence++;
                 do_gettimeofday(&buf->vb.v4l2_buf.timestamp);
                 vb2_set_plane_payload(&buf->vb, 0, size);
                 vb2_buffer_done(&buf->vb, state);
                 list_del(&buf->list);
         }
  
         spin_unlock_irqrestore(&usbtv->buflock, flags);
  }
  
  /* Got image data. Each packet contains a number of 256-word chunks we
   * compose the image from. */
  static void usbtv_iso_cb(struct urb *ip)
  {
         int ret;
         int i, pkt_ok = 1;
         struct usbtv *usbtv = (struct usbtv *)ip->context;
  
         switch (ip->status) {
         /* All fine. */
         case 0:
                 break;
         /* Device disconnected or capture stopped? */
         case -ENODEV:
         case -ENOENT:
         case -ECONNRESET:
         case -ESHUTDOWN:
                 return;
         /* Unknown error. Retry. */
         default:
                 dev_warn(usbtv->dev, "Bad response for ISO request.\n");
                 pkt_ok = 0;
         }
        
         if (pkt_ok)
            for (i = 0; i < ip->number_of_packets; i++) {
                    int size = ip->iso_frame_desc[i].actual_length;
                    unsigned char *data = ip->transfer_buffer +
                                    ip->iso_frame_desc[i].offset;
                    int offset;
                    
                    for (offset = 0; USBTV_CHUNK_SIZE * offset < size; offset++)
                            usbtv_image_chunk(usbtv,
                                    (u32 *)&data[USBTV_CHUNK_SIZE * offset]);
            }
         
         ret = usb_submit_urb(ip, GFP_ATOMIC);
         if (ret < 0) {
                 dev_warn(usbtv->dev, "Could not resubmit ISO URB\n");
         }
  }
  
  static struct urb *usbtv_setup_iso_transfer(struct usbtv *usbtv)
  {
         struct urb *ip;
         int size = usbtv->iso_size;
         int i;
  
         ip = usb_alloc_urb(USBTV_ISOC_PACKETS, GFP_KERNEL);
         if (ip == NULL)
                 return NULL;
  
         ip->dev = usbtv->udev;
         ip->context = usbtv;
         ip->pipe = usb_rcvisocpipe(usbtv->udev, USBTV_VIDEO_ENDP);
         ip->interval = usbtv->iso_interval;
         ip->transfer_flags = URB_ISO_ASAP;
         ip->transfer_buffer = kzalloc(size * USBTV_ISOC_PACKETS,
                                                 GFP_KERNEL);
         ip->complete = usbtv_iso_cb;
         
         usb_fill_int_urb(ip, usbtv->udev, usb_rcvisocpipe(usbtv->udev, USBTV_VIDEO_ENDP),
           ip->transfer_buffer,
           size * USBTV_ISOC_PACKETS, usbtv_iso_cb, usbtv, usbtv->iso_interval);
         
         ip->number_of_packets = USBTV_ISOC_PACKETS;
         ip->transfer_buffer_length = size * USBTV_ISOC_PACKETS;
         for (i = 0; i < USBTV_ISOC_PACKETS; i++) {
                 ip->iso_frame_desc[i].offset = size * i;
                 ip->iso_frame_desc[i].length = size;
         }
  
         return ip;
  }
  
  static void usbtv_stop(struct usbtv *usbtv)
  {
         int i;
         unsigned long flags;
  
         /* Cancel running transfers. */
         for (i = 0; i < USBTV_ISOC_TRANSFERS; i++) {
                 struct urb *ip = usbtv->isoc_urbs[i];
                 if (ip == NULL)
                         continue;
                 usb_kill_urb(ip);
                 kfree(ip->transfer_buffer);
                 usb_free_urb(ip);
                 usbtv->isoc_urbs[i] = NULL;
         }
  
         /* Return buffers to userspace. */
         spin_lock_irqsave(&usbtv->buflock, flags);
         while (!list_empty(&usbtv->bufs)) {
                 struct usbtv_buf *buf = list_first_entry(&usbtv->bufs,
                                                 struct usbtv_buf, list);
                 vb2_buffer_done(&buf->vb, VB2_BUF_STATE_ERROR);
                 list_del(&buf->list);
         }
         spin_unlock_irqrestore(&usbtv->buflock, flags);
  }
  
  static int usbtv_start(struct usbtv *usbtv)
  {
         int i;
         int ret;
  
         ret = usb_set_interface(usbtv->udev, 0, 0);
         if (ret < 0)
                 return ret;
  
         ret = usbtv_setup_capture(usbtv);
         if (ret < 0)
                 return ret;
  
         ret = usb_set_interface(usbtv->udev, 0, 1);
         if (ret < 0)
                 return ret;
  
         for (i = 0; i < USBTV_ISOC_TRANSFERS; i++) {
                 struct urb *ip;
  
                 ip = usbtv_setup_iso_transfer(usbtv);
                 if (ip == NULL) {
                         ret = -ENOMEM;
                         goto start_fail;
                 }
                 usbtv->isoc_urbs[i] = ip;
  
                 ret = usb_submit_urb(ip, GFP_KERNEL);
                 if (ret < 0)
                         goto start_fail;
         }
  
         return 0;
  
  start_fail:
         usbtv_stop(usbtv);
         return ret;
  }
  
  struct usb_device_id usbtv_id_table[] = {
         { USB_DEVICE(0x1b71, 0x3002) },
         {}
  };
  MODULE_DEVICE_TABLE(usb, usbtv_id_table);
  
  static int usbtv_querycap(struct file *file, void *priv,
                                 struct v4l2_capability *cap)
  {
         struct usbtv *dev = video_drvdata(file);
  
         strlcpy(cap->driver, "usbtv", sizeof(cap->driver));
         strlcpy(cap->card, "usbtv", sizeof(cap->card));
         usb_make_path(dev->udev, cap->bus_info, sizeof(cap->bus_info));
         cap->device_caps = V4L2_CAP_VIDEO_CAPTURE;
         cap->device_caps |= V4L2_CAP_READWRITE | V4L2_CAP_STREAMING;
         cap->capabilities = cap->device_caps | V4L2_CAP_DEVICE_CAPS;
         return 0;
  }
  
  static int usbtv_enum_input(struct file *file, void *priv,
                                         struct v4l2_input *i)
  {
         if (i->index > 0)
                 return -EINVAL;
  
         strlcpy(i->name, "Composite", sizeof(i->name));
         i->type = V4L2_INPUT_TYPE_CAMERA;
         i->std = V4L2_STD_525_60;
         return 0;
  }
  
  static int usbtv_enum_fmt_vid_cap(struct file *file, void  *priv,
                                         struct v4l2_fmtdesc *f)
  {
         if (f->index > 0)
                 return -EINVAL;
  
         strlcpy(f->description, "16 bpp YUY2, 4:2:2, packed",
                                         sizeof(f->description));
         f->pixelformat = V4L2_PIX_FMT_YUYV;
         return 0;
  }
  
  static int usbtv_fmt_vid_cap(struct file *file, void *priv,
                                         struct v4l2_format *f)
  {
         f->fmt.pix.width = USBTV_WIDTH;
         f->fmt.pix.height = USBTV_HEIGHT;
         f->fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
         f->fmt.pix.field = V4L2_FIELD_INTERLACED;
         f->fmt.pix.bytesperline = USBTV_WIDTH * 2;
         f->fmt.pix.sizeimage = (f->fmt.pix.bytesperline * f->fmt.pix.height);
         f->fmt.pix.colorspace = V4L2_COLORSPACE_SMPTE170M;
         f->fmt.pix.priv = 0;
         return 0;
  }
  
  static int usbtv_g_std(struct file *file, void *priv, v4l2_std_id *norm)
  {
         *norm = V4L2_STD_525_60;
         return 0;
  }
  
  static int usbtv_g_input(struct file *file, void *priv, unsigned int *i)
  {
         *i = 0;
         return 0;
  }
  
  static int usbtv_s_input(struct file *file, void *priv, unsigned int i)
  {
         if (i > 0)
                 return -EINVAL;
         return 0;
  }
  
  static int usbtv_s_std(struct file *file, void *priv, v4l2_std_id norm)
  {
         if (norm & V4L2_STD_525_60)
                 return 0;
         return -EINVAL;
  }
  
  struct v4l2_ioctl_ops usbtv_ioctl_ops = {
         .vidioc_querycap = usbtv_querycap,
         .vidioc_enum_input = usbtv_enum_input,
         .vidioc_enum_fmt_vid_cap = usbtv_enum_fmt_vid_cap,
         .vidioc_g_fmt_vid_cap = usbtv_fmt_vid_cap,
         .vidioc_try_fmt_vid_cap = usbtv_fmt_vid_cap,
         .vidioc_s_fmt_vid_cap = usbtv_fmt_vid_cap,
         .vidioc_g_std = usbtv_g_std,
         .vidioc_s_std = usbtv_s_std,
         .vidioc_g_input = usbtv_g_input,
         .vidioc_s_input = usbtv_s_input,
  
         .vidioc_reqbufs = vb2_ioctl_reqbufs,
         .vidioc_prepare_buf = vb2_ioctl_prepare_buf,
         .vidioc_querybuf = vb2_ioctl_querybuf,
         .vidioc_create_bufs = vb2_ioctl_create_bufs,
         .vidioc_qbuf = vb2_ioctl_qbuf,
         .vidioc_dqbuf = vb2_ioctl_dqbuf,
         .vidioc_streamon = vb2_ioctl_streamon,
         .vidioc_streamoff = vb2_ioctl_streamoff,
  };
  
  struct v4l2_file_operations usbtv_fops = {
         .owner = THIS_MODULE,
         .unlocked_ioctl = video_ioctl2,
         .mmap = vb2_fop_mmap,
         .open = v4l2_fh_open,
         .release = vb2_fop_release,
         .read = vb2_fop_read,
         .poll = vb2_fop_poll,
  };
  
  static int usbtv_queue_setup(struct vb2_queue *vq,
         const struct v4l2_format *v4l_fmt, unsigned int *nbuffers,
         unsigned int *nplanes, unsigned int sizes[], void *alloc_ctxs[])
  {
         if (*nbuffers < 3)
                 *nbuffers = 3;
         *nplanes = 1;
         sizes[0] = USBTV_WIDTH * USBTV_HEIGHT / 2 * sizeof(u32);
  
         return 0;
  }
  
  static void usbtv_buf_queue(struct vb2_buffer *vb)
  {
         struct usbtv *usbtv = vb2_get_drv_priv(vb->vb2_queue);
         struct usbtv_buf *buf = container_of(vb, struct usbtv_buf, vb);
         unsigned long flags;
  
         if (usbtv->udev == NULL) {
                 vb2_buffer_done(vb, VB2_BUF_STATE_ERROR);
                 return;
         }
  
         spin_lock_irqsave(&usbtv->buflock, flags);
         list_add_tail(&buf->list, &usbtv->bufs);
         spin_unlock_irqrestore(&usbtv->buflock, flags);
  }
  
  static int usbtv_start_streaming(struct vb2_queue *vq, unsigned int count)
  {
         struct usbtv *usbtv = vb2_get_drv_priv(vq);
  
         if (usbtv->udev == NULL)
                 return -ENODEV;
  
         return usbtv_start(usbtv);
  }
  
  static int usbtv_stop_streaming(struct vb2_queue *vq)
  {
         struct usbtv *usbtv = vb2_get_drv_priv(vq);
  
         if (usbtv->udev == NULL)
                 return -ENODEV;
  
         usbtv_stop(usbtv);
         return 0;
  }
  
  struct vb2_ops usbtv_vb2_ops = {
         .queue_setup = usbtv_queue_setup,
         .buf_queue = usbtv_buf_queue,
         .start_streaming = usbtv_start_streaming,
         .stop_streaming = usbtv_stop_streaming,
  };
  
  static void usbtv_release(struct v4l2_device *v4l2_dev)
  {
         struct usbtv *usbtv = container_of(v4l2_dev, struct usbtv, v4l2_dev);
  
         v4l2_device_unregister(&usbtv->v4l2_dev);
         vb2_queue_release(&usbtv->vb2q);
         kfree(usbtv);
  }
  
  static int usbtv_probe(struct usb_interface *intf,
         const struct usb_device_id *id)
  {
         int ret;
         int size, interval;
         struct device *dev = &intf->dev;
         struct usbtv *usbtv;
  
         /* Checks that the device is what we think it is. */
         if (intf->num_altsetting != 2)
                 return -ENODEV;
         if (intf->altsetting[1].desc.bNumEndpoints != 4)
                 return -ENODEV;
  
         /* Packet size is split into 11 bits of base size and count of
          * extra multiplies of it.*/
         size = usb_endpoint_maxp(&intf->altsetting[1].endpoint[0].desc);
         size = (size & 0x07ff) * (((size & 0x1800) >> 11) + 1);
         
         interval = intf->altsetting[1].endpoint[0].desc.bInterval;
         
         printk("size is %d, interval is %d\n", size, interval);
  
         /* Device structure */
         usbtv = kzalloc(sizeof(struct usbtv), GFP_KERNEL);
         if (usbtv == NULL)
                 return -ENOMEM;
         usbtv->dev = dev;
         usbtv->udev = usb_get_dev(interface_to_usbdev(intf));
         usbtv->iso_size = size;
         usbtv->iso_interval = interval;
         spin_lock_init(&usbtv->buflock);
         mutex_init(&usbtv->v4l2_lock);
         mutex_init(&usbtv->vb2q_lock);
         INIT_LIST_HEAD(&usbtv->bufs);
  
         /* videobuf2 structure */
         usbtv->vb2q.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
         usbtv->vb2q.io_modes = VB2_MMAP | VB2_USERPTR | VB2_READ;
         usbtv->vb2q.drv_priv = usbtv;
         usbtv->vb2q.buf_struct_size = sizeof(struct usbtv_buf);
         usbtv->vb2q.ops = &usbtv_vb2_ops;
         usbtv->vb2q.mem_ops = &vb2_vmalloc_memops;
         usbtv->vb2q.lock = &usbtv->vb2q_lock;
         ret = vb2_queue_init(&usbtv->vb2q);
         if (ret < 0) {
                 dev_warn(dev, "Could not initialize videobuf2 queue\n");
                 goto usbtv_fail;
         }
  
         /* v4l2 structure */
         usbtv->v4l2_dev.release = usbtv_release;
         ret = v4l2_device_register(dev, &usbtv->v4l2_dev);
         if (ret < 0) {
                 dev_warn(dev, "Could not register v4l2 device\n");
                 goto v4l2_fail;
         }
  
         usb_set_intfdata(intf, usbtv);
  
         /* Video structure */
         strlcpy(usbtv->vdev.name, "usbtv", sizeof(usbtv->vdev.name));
         usbtv->vdev.v4l2_dev = &usbtv->v4l2_dev;
         usbtv->vdev.release = video_device_release_empty;
         usbtv->vdev.fops = &usbtv_fops;
         usbtv->vdev.ioctl_ops = &usbtv_ioctl_ops;
         usbtv->vdev.tvnorms = V4L2_STD_525_60;
         usbtv->vdev.queue = &usbtv->vb2q;
         usbtv->vdev.lock = &usbtv->v4l2_lock;
         set_bit(V4L2_FL_USE_FH_PRIO, &usbtv->vdev.flags);
         video_set_drvdata(&usbtv->vdev, usbtv);
         ret = video_register_device(&usbtv->vdev, VFL_TYPE_GRABBER, -1);
         if (ret < 0) {
                 dev_warn(dev, "Could not register video device\n");
                 goto vdev_fail;
         }
  
         dev_info(dev, "Fushicai USBTV007 Video Grabber\n");
         return 0;
  
  vdev_fail:
         v4l2_device_unregister(&usbtv->v4l2_dev);
  v4l2_fail:
         vb2_queue_release(&usbtv->vb2q);
  usbtv_fail:
         kfree(usbtv);
  
         return ret;
  }
  
  static void usbtv_disconnect(struct usb_interface *intf)
  {
         struct usbtv *usbtv = usb_get_intfdata(intf);
  
         mutex_lock(&usbtv->vb2q_lock);
         mutex_lock(&usbtv->v4l2_lock);
  
         usbtv_stop(usbtv);
         usb_set_intfdata(intf, NULL);
         video_unregister_device(&usbtv->vdev);
         v4l2_device_disconnect(&usbtv->v4l2_dev);
         usb_put_dev(usbtv->udev);
         usbtv->udev = NULL;
  
         mutex_unlock(&usbtv->v4l2_lock);
         mutex_unlock(&usbtv->vb2q_lock);
  
         v4l2_device_put(&usbtv->v4l2_dev);
  }
  
  MODULE_AUTHOR("Lubomir Rintel");
  MODULE_DESCRIPTION("Fushicai USBTV007 Video Grabber Driver");
  MODULE_LICENSE("Dual BSD/GPL");
  
  struct usb_driver usbtv_usb_driver = {
         .name = "usbtv",
         .id_table = usbtv_id_table,
         .probe = usbtv_probe,
         .disconnect = usbtv_disconnect,
  };
  
  module_usb_driver(usbtv_usb_driver);
  