drivers/media/usb/usbtv/usbtv.c

/*
 * 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/videodev2.h>

#include <media/v4l2-device.h>
#include <media/v4l2-ioctl.h>
#include <media/videobuf2-core.h>
#include <media/videobuf2-vmalloc.h>

/* 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	16
#define USBTV_ISOC_PACKETS	8

#define USBTV_WIDTH		720
#define USBTV_HEIGHT		480

#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;

	enum {
		USBTV_COMPOSITE_INPUT,
		USBTV_SVIDEO_INPUT,
	} input;
	int iso_size;
	unsigned int sequence;
	struct urb *isoc_urbs[USBTV_ISOC_TRANSFERS];
};

static int usbtv_set_regs(struct usbtv *usbtv, const u16 regs[][2], int size)
{
	int ret;
	int pipe = usb_rcvctrlpipe(usbtv->udev, 0);
	int i;

	for (i = 0; i < size; i++) {
		u16 index = regs[i][0];
		u16 value = regs[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;
}

static int usbtv_select_input(struct usbtv *usbtv, int input)
{
	int ret;

	static const u16 composite[][2] = {
		{ USBTV_BASE + 0x0105, 0x0060 },
		{ USBTV_BASE + 0x011f, 0x00f2 },
		{ USBTV_BASE + 0x0127, 0x0060 },
		{ USBTV_BASE + 0x00ae, 0x0010 },
		{ USBTV_BASE + 0x0284, 0x00aa },
		{ USBTV_BASE + 0x0239, 0x0060 },
	};

	static const u16 svideo[][2] = {
		{ USBTV_BASE + 0x0105, 0x0010 },
		{ USBTV_BASE + 0x011f, 0x00ff },
		{ USBTV_BASE + 0x0127, 0x0060 },
		{ USBTV_BASE + 0x00ae, 0x0030 },
		{ USBTV_BASE + 0x0284, 0x0088 },
		{ USBTV_BASE + 0x0239, 0x0060 },
	};

	switch (input) {
	case USBTV_COMPOSITE_INPUT:
		ret = usbtv_set_regs(usbtv, composite, ARRAY_SIZE(composite));
		break;
	case USBTV_SVIDEO_INPUT:
		ret = usbtv_set_regs(usbtv, svideo, ARRAY_SIZE(svideo));
		break;
	default:
		ret = -EINVAL;
	}

	if (!ret)
		usbtv->input = input;

	return ret;
}

static int usbtv_setup_capture(struct usbtv *usbtv)
{
	int ret;
	static const u16 setup[][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 },
		{ USBTV_BASE + 0x001a, 0x0079 },
		{ USBTV_BASE + 0x0100, 0x00d3 },
		{ USBTV_BASE + 0x010e, 0x0068 },
		{ USBTV_BASE + 0x010f, 0x009c },
		{ USBTV_BASE + 0x0112, 0x00f0 },
		{ USBTV_BASE + 0x0115, 0x0015 },
		{ USBTV_BASE + 0x0117, 0x0000 },
		{ USBTV_BASE + 0x0118, 0x00fc },
		{ USBTV_BASE + 0x012d, 0x0004 },
		{ USBTV_BASE + 0x012f, 0x0008 },
		{ USBTV_BASE + 0x0220, 0x002e },
		{ USBTV_BASE + 0x0225, 0x0008 },
		{ USBTV_BASE + 0x024e, 0x0002 },
		{ 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 },
		{ USBTV_BASE + 0x024e, 0x0002 },
		{ USBTV_BASE + 0x024f, 0x0002 },
	};

	ret = usbtv_set_regs(usbtv, setup, ARRAY_SIZE(setup));
	if (ret)
		return ret;

	ret = usbtv_select_input(usbtv, usbtv->input);
	if (ret)
		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;
	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 = 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++;
		v4l2_get_timestamp(&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;
	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");
		goto resubmit;
	}

	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]);
	}

resubmit:
	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 = 1;
	ip->transfer_flags = URB_ISO_ASAP;
	ip->transfer_buffer = kzalloc(size * USBTV_ISOC_PACKETS,
						GFP_KERNEL);
	ip->complete = usbtv_iso_cb;
	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)
{
	switch (i->index) {
	case USBTV_COMPOSITE_INPUT:
		strlcpy(i->name, "Composite", sizeof(i->name));
		break;
	case USBTV_SVIDEO_INPUT:
		strlcpy(i->name, "S-Video", sizeof(i->name));
		break;
	default:
		return -EINVAL;
	}

	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)
{
	struct usbtv *usbtv = video_drvdata(file);
	*i = usbtv->input;
	return 0;
}

static int usbtv_s_input(struct file *file, void *priv, unsigned int i)
{
	struct usbtv *usbtv = video_drvdata(file);
	return usbtv_select_input(usbtv, i);
}

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 < 2)
		*nbuffers = 2;
	*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;
	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);

	/* 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;
	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.timestamp_type = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
	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);