自己写的uvc驱动支持IP2977/ip2970

Love The Way You Lie 2022-06-11 02:19 180阅读 0赞

/* 作者: 453411484@qq.com 
     * 此驱动程序是基于linux2.6.31.14内核
     * 上一篇自己写的uvc驱动程序是针对环宇飞扬6190来写的，有一些缺点，这些缺点在本次的驱动
     * 中进行了修改此uvc驱动是针对IP2977进行了支持，根据IP2977芯片厂商提供的修改手册进行了修改。
     * 此驱动程序虽然支持IP2977摄像头，但是显示效果不太好，此驱动只是针对学习使用。
     */
    
    #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 <linux/mm.h>
    #include <asm/atomic.h>
    #include <asm/unaligned.h>
    
    #include <media/v4l2-common.h>
    #include <media/v4l2-ioctl.h>
    #include <media/videobuf-core.h>
    
    #include "uvcvideo.h"
    
    /* 参考 drivers/media/video/uvc */
    
    #define MYUVC_URBS 5
    
    /* Values for bmHeaderInfo (Video and Still Image Payload Headers, 2.4.3.3) */
    #define UVC_STREAM_EOH	(1 << 7)
    #define UVC_STREAM_ERR	(1 << 6)
    #define UVC_STREAM_STI	(1 << 5)
    #define UVC_STREAM_RES	(1 << 4)
    #define UVC_STREAM_SCR	(1 << 3)
    #define UVC_STREAM_PTS	(1 << 2)
    #define UVC_STREAM_EOF	(1 << 1)
    #define UVC_STREAM_FID	(1 << 0)
    
    
    struct myuvc_streaming_control {
    	__u16 bmHint;
    	__u8  bFormatIndex;
    	__u8  bFrameIndex;
    	__u32 dwFrameInterval;
    	__u16 wKeyFrameRate;
    	__u16 wPFrameRate;
    	__u16 wCompQuality;
    	__u16 wCompWindowSize;
    	__u16 wDelay;
    	__u32 dwMaxVideoFrameSize;
    	__u32 dwMaxPayloadTransferSize;
    	__u32 dwClockFrequency;
    	__u8  bmFramingInfo;
    	__u8  bPreferedVersion;
    	__u8  bMinVersion;
    	__u8  bMaxVersion;
    };
    
    
    
    struct frame_desc {
        int width;
        int height;
    };
    
    /* 参考uvc_video_queue定义一些结构体 */
    struct myuvc_buffer {    
        struct v4l2_buffer buf;
        int state;
        int vma_use_count; /* 表示是否已经被mmap */
        wait_queue_head_t wait;  /* APP要读某个缓冲区,如果无数据,在此休眠 */
    	struct list_head stream;
    	struct list_head irq;    
    };
    
    struct myuvc_queue {
        void *mem;
        int count;
        int buf_size;    
        struct myuvc_buffer buffer[32];
    
    	struct urb *urb[32];
    	char *urb_buffer[32];
    	dma_addr_t urb_dma[32];
    	unsigned int urb_size;
    
    	struct list_head mainqueue;   /* 供APP消费用 */
    	struct list_head irqqueue;    /* 供底层驱动生产用 */
    };
    
    static struct myuvc_queue myuvc_queue;
    
    static struct video_device *myuvc_vdev;
    static struct usb_device *myuvc_udev;
    
    static int myuvc_bEndpointAddress = 0x82;
    static int myuvc_streaming_intf;
    static int myuvc_control_intf;
    static struct v4l2_format myuvc_format;
    
    static struct frame_desc frames[] = {
       {640, 480}, {320, 240}, {160, 120}};
    static int frame_idx = 1;
    static int bBitsPerPixel = 0; /* lsusb -v -d 0x1e4e:  "bBitsPerPixel" */
    static int uvc_version = 0x0100; /* lsusb -v -d 0x1b3b: bcdUVC */
    
    static int ProcessingUnitID = 3;  /* lsusb -v -d 0x1b3b: PROCESSING_UNIT */
    
    /* 以后再设置 */
    static int wMaxPacketSize = 800;
    static int myuvc_streaming_bAlternateSetting = 5;
    static int dwMaxVideoFrameSize = 77312;
    
    static struct myuvc_streaming_control myuvc_params;
    
    static int last_fid = -1;
    
    /* A2 参考 uvc_v4l2_do_ioctl */
    static int myuvc_vidioc_querycap(struct file *file, void  *priv,
    					struct v4l2_capability *cap)
    {    
        memset(cap, 0, sizeof *cap);
        strcpy(cap->driver, "myuvc");
        strcpy(cap->card, "myuvc");
        cap->version = 1;
        
        cap->capabilities = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING;
     
    	return 0;
    }
    
    /* A3 列举支持哪种格式
     * 参考: uvc_fmts 数组
     */
    static int myuvc_vidioc_enum_fmt_vid_cap(struct file *file, void  *priv,
    					struct v4l2_fmtdesc *f)
    {
        /* 人工查看描述符可知我们用的摄像头只支持1种格式 */
    	if (f->index >= 1)
    		return -EINVAL;
    
    	strcpy(f->description, "MJPEG");
    	f->pixelformat = V4L2_PIX_FMT_MJPEG;    
    	//f->flags       = ;
    	f->type        = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        
    	return 0;
    }
    
    /* A4 返回当前所使用的格式 */
    static int myuvc_vidioc_g_fmt_vid_cap(struct file *file, void *priv,
    					struct v4l2_format *f)
    {
        memcpy(f, &myuvc_format, sizeof(myuvc_format));
    	return (0);
    }
    
    /* A5 测试驱动程序是否支持某种格式, 强制设置该格式 
     * 参考: uvc_v4l2_try_format
     *       myvivi_vidioc_try_fmt_vid_cap
     */
    static int myuvc_vidioc_try_fmt_vid_cap(struct file *file, void *priv,
    			struct v4l2_format *f)
    {
        if (f->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
        {
            return -EINVAL;
        }
    
        if (f->fmt.pix.pixelformat != V4L2_PIX_FMT_MJPEG)
            return -EINVAL;
        
        /* 调整format的width, height, 
         * 计算bytesperline, sizeimage
         */
    
        /* 人工查看描述符, 确定支持哪几种分辨率 */
        f->fmt.pix.width  = frames[frame_idx].width;
        f->fmt.pix.height = frames[frame_idx].height;
    
    	/* 对于MJPEG数据类型来说，bBitsPerPixel是无法知道的。因此我们设为0 */
    	f->fmt.pix.bytesperline =
    		(f->fmt.pix.width * bBitsPerPixel) >> 3;
    	
    	/* 一帧数据最大为dwMaxVideoFrameSize=77312,是由确定带宽时确定出来的。 */
    	f->fmt.pix.sizeimage = dwMaxVideoFrameSize;
    
    	f->fmt.pix.field      = V4L2_FIELD_NONE;
    	/* 由描述符bColorPrimaries  1 (BT.709,sRGB)可知 */
    	f->fmt.pix.colorspace = V4L2_COLORSPACE_SRGB;
    	f->fmt.pix.priv       = 0;		/* private data, depends on pixelformat */
        
        return 0;
    }
    
    /* A6 参考 myvivi_vidioc_s_fmt_vid_cap */
    static int myuvc_vidioc_s_fmt_vid_cap(struct file *file, void *priv,
    					struct v4l2_format *f)
    {
    	int ret = myuvc_vidioc_try_fmt_vid_cap(file, NULL, f);
    	if (ret < 0)
    		return ret;
    
        memcpy(&myuvc_format, f, sizeof(myuvc_format));
        
        return 0;
    }
    
    static int myuvc_free_buffers(void)
    {
        if (myuvc_queue.mem)
        {
            vfree(myuvc_queue.mem);
            memset(&myuvc_queue, 0, sizeof(myuvc_queue));
            myuvc_queue.mem = NULL;
        }
        return 0;
    }
    
    /* A7 APP调用该ioctl让驱动程序分配若干个缓存, APP将从这些缓存中读到视频数据 
     * 参考: uvc_alloc_buffers
     */
    static int myuvc_vidioc_reqbufs(struct file *file, void *priv,
    			  struct v4l2_requestbuffers *p)
    {
        int nbuffers = p->count;
        int bufsize  = PAGE_ALIGN(myuvc_format.fmt.pix.sizeimage);
        unsigned int i;
        void *mem = NULL;
        int ret;
    
        if ((ret = myuvc_free_buffers()) < 0)
            goto done;
    
        /* Bail out if no buffers should be allocated. */
        if (nbuffers == 0)
            goto done;
    
        /* Decrement the number of buffers until allocation succeeds. */
        for (; nbuffers > 0; --nbuffers) {
            mem = vmalloc_32(nbuffers * bufsize);
            if (mem != NULL)
                break;
        }
    
        if (mem == NULL) {
            ret = -ENOMEM;
            goto done;
        }
    
        /* 这些缓存是一次性作为一个整体来分配的 */
        memset(&myuvc_queue, 0, sizeof(myuvc_queue));
    
    	INIT_LIST_HEAD(&myuvc_queue.mainqueue);
    	INIT_LIST_HEAD(&myuvc_queue.irqqueue);
    
        for (i = 0; i < nbuffers; ++i) {
            myuvc_queue.buffer[i].buf.index = i;
            myuvc_queue.buffer[i].buf.m.offset = i * bufsize;
            myuvc_queue.buffer[i].buf.length = myuvc_format.fmt.pix.sizeimage;
            myuvc_queue.buffer[i].buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
            myuvc_queue.buffer[i].buf.sequence = 0;
            myuvc_queue.buffer[i].buf.field = V4L2_FIELD_NONE;
            myuvc_queue.buffer[i].buf.memory = V4L2_MEMORY_MMAP;
            myuvc_queue.buffer[i].buf.flags = 0;
            myuvc_queue.buffer[i].state     = VIDEOBUF_IDLE;
            init_waitqueue_head(&myuvc_queue.buffer[i].wait);
        }
    
        myuvc_queue.mem = mem;
        myuvc_queue.count = nbuffers;
        myuvc_queue.buf_size = bufsize;
        ret = nbuffers;
    
    done:
        return ret;
    }
    
    /* A8 查询缓存状态, 比如地址信息(APP可以用mmap进行映射) 
     * 参考 uvc_query_buffer
     */
    static int myuvc_vidioc_querybuf(struct file *file, void *priv, struct v4l2_buffer *v4l2_buf)
    {
        int ret = 0;
        
    	if (v4l2_buf->index >= myuvc_queue.count) {
    		ret = -EINVAL;
    		goto done;
    	}
    
        memcpy(v4l2_buf, &myuvc_queue.buffer[v4l2_buf->index].buf, sizeof(*v4l2_buf));
    
        /* 更新flags */
    	if (myuvc_queue.buffer[v4l2_buf->index].vma_use_count)
    		v4l2_buf->flags |= V4L2_BUF_FLAG_MAPPED;
    
    
    	switch (myuvc_queue.buffer[v4l2_buf->index].state) {
        	case VIDEOBUF_ERROR:
        	case VIDEOBUF_DONE:
        		v4l2_buf->flags |= V4L2_BUF_FLAG_DONE;
        		break;
        	case VIDEOBUF_QUEUED:
        	case VIDEOBUF_ACTIVE:
        		v4l2_buf->flags |= V4L2_BUF_FLAG_QUEUED;
        		break;
        	case VIDEOBUF_IDLE:
        	default:
        		break;
    	}
    
    done:    
    	return ret;
    }
    
    /* A10 把缓冲区放入队列, 底层的硬件操作函数将会把数据放入这个队列的缓存 
     * 参考: uvc_queue_buffer
     */
    static int myuvc_vidioc_qbuf(struct file *file, void *priv, struct v4l2_buffer *v4l2_buf)
    {
        struct myuvc_buffer *buf;
    
        /* 0. APP传入的v4l2_buf可能有问题, 要做判断 */
    
    	if (v4l2_buf->type != V4L2_BUF_TYPE_VIDEO_CAPTURE ||
    	    v4l2_buf->memory != V4L2_MEMORY_MMAP) {
    		return -EINVAL;
    	}
    
    	if (v4l2_buf->index >= myuvc_queue.count) {
    		return -EINVAL;
    	}
    
        buf = &myuvc_queue.buffer[v4l2_buf->index];
    
    	if (buf->state != VIDEOBUF_IDLE) {
    		return -EINVAL;
    	}
    
    
        /* 1. 修改状态 */
    	buf->state = VIDEOBUF_QUEUED;
    	buf->buf.bytesused = 0;
    
        /* 2. 放入2个队列 */
        /* 队列1: 供APP使用 
         * 当缓冲区没有数据时,放入mainqueue队列
         * 当缓冲区有数据时, APP从mainqueue队列中取出
         */
    	list_add_tail(&buf->stream, &myuvc_queue.mainqueue);
    
        /* 队列2: 供产生数据的函数使用
         * 当采集到数据时,从irqqueue队列中取出第1个缓冲区,存入数据
         */
    	list_add_tail(&buf->irq, &myuvc_queue.irqqueue);
        
    	return 0;
    }
    
    static void myuvc_print_streaming_params(struct myuvc_streaming_control *ctrl)
    {
        printk("video params:\n");
        printk("bmHint                   = %d\n", ctrl->bmHint);
        printk("bFormatIndex             = %d\n", ctrl->bFormatIndex);
        printk("bFrameIndex              = %d\n", ctrl->bFrameIndex);
        printk("dwFrameInterval          = %d\n", ctrl->dwFrameInterval);
        printk("wKeyFrameRate            = %d\n", ctrl->wKeyFrameRate);
        printk("wPFrameRate              = %d\n", ctrl->wPFrameRate);
        printk("wCompQuality             = %d\n", ctrl->wCompQuality);
        printk("wCompWindowSize          = %d\n", ctrl->wCompWindowSize);
        printk("wDelay                   = %d\n", ctrl->wDelay);
        printk("dwMaxVideoFrameSize      = %d\n", ctrl->dwMaxVideoFrameSize);
        printk("dwMaxPayloadTransferSize = %d\n", ctrl->dwMaxPayloadTransferSize);
        printk("dwClockFrequency         = %d\n", ctrl->dwClockFrequency);
        printk("bmFramingInfo            = %d\n", ctrl->bmFramingInfo);
        printk("bPreferedVersion         = %d\n", ctrl->bPreferedVersion);
        printk("bMinVersion              = %d\n", ctrl->bMinVersion);
        printk("bMinVersion              = %d\n", ctrl->bMinVersion);
    }
    
    
    /* 参考: uvc_get_video_ctrl 
     (ret = uvc_get_video_ctrl(video, probe, 1, GET_CUR)) 
     static int uvc_get_video_ctrl(struct uvc_video_device *video,
         struct uvc_streaming_control *ctrl, int probe, __u8 query)
     */
    static int myuvc_get_streaming_params(struct myuvc_streaming_control *ctrl)
    {
    	__u8 *data;
    	__u16 size;
    	int ret;
    	__u8 type = USB_TYPE_CLASS | USB_RECIP_INTERFACE;
    	unsigned int pipe;
    
    	size = uvc_version >= 0x0110 ? 34 : 26;
    	data = kmalloc(size, GFP_KERNEL);
    	if (data == NULL)
    		return -ENOMEM;
       
    	pipe = (GET_CUR & 0x80) ? usb_rcvctrlpipe(myuvc_udev, 0)
    			      : usb_sndctrlpipe(myuvc_udev, 0);
    	type |= (GET_CUR & 0x80) ? USB_DIR_IN : USB_DIR_OUT;
    
    	ret = usb_control_msg(myuvc_udev, pipe, GET_CUR, type, VS_PROBE_CONTROL << 8,
    			0 << 8 | myuvc_streaming_intf, data, size, 5000);
    
        if (ret < 0)
            goto done;
    
    	ctrl->bmHint = le16_to_cpup((__le16 *)&data[0]);
    	ctrl->bFormatIndex = data[2];
    	ctrl->bFrameIndex = data[3];
    	ctrl->dwFrameInterval = le32_to_cpup((__le32 *)&data[4]);
    	ctrl->wKeyFrameRate = le16_to_cpup((__le16 *)&data[8]);
    	ctrl->wPFrameRate = le16_to_cpup((__le16 *)&data[10]);
    	ctrl->wCompQuality = le16_to_cpup((__le16 *)&data[12]);
    	ctrl->wCompWindowSize = le16_to_cpup((__le16 *)&data[14]);
    	ctrl->wDelay = le16_to_cpup((__le16 *)&data[16]);
    	ctrl->dwMaxVideoFrameSize = get_unaligned_le32(&data[18]);
    	ctrl->dwMaxPayloadTransferSize = get_unaligned_le32(&data[22]);
    
    	if (size == 34) {
    		ctrl->dwClockFrequency = get_unaligned_le32(&data[26]);
    		ctrl->bmFramingInfo = data[30];
    		ctrl->bPreferedVersion = data[31];
    		ctrl->bMinVersion = data[32];
    		ctrl->bMaxVersion = data[33];
    	} else {
    		//ctrl->dwClockFrequency = video->dev->clock_frequency;
    		ctrl->bmFramingInfo = 0;
    		ctrl->bPreferedVersion = 0;
    		ctrl->bMinVersion = 0;
    		ctrl->bMaxVersion = 0;
    	}
    
    done:
        kfree(data);
        
        return (ret < 0) ? ret : 0;
    }
    
    /* 参考: uvc_v4l2_try_format ∕uvc_probe_video 
     *       uvc_set_video_ctrl(video, probe, 1)
     */
    static int myuvc_try_streaming_params(struct myuvc_streaming_control *ctrl)
    {
        __u8 *data;
        __u16 size;
        int ret;
    	__u8 type = USB_TYPE_CLASS | USB_RECIP_INTERFACE;
    	unsigned int pipe;
        
    	memset(ctrl, 0, sizeof *ctrl);
        
    	ctrl->bmHint = 1;	/* dwFrameInterval */
    	ctrl->bFormatIndex = 1;
    	ctrl->bFrameIndex  = frame_idx + 1;
    	ctrl->dwFrameInterval = 333333;
    
    
        size = uvc_version >= 0x0110 ? 34 : 26;
        data = kzalloc(size, GFP_KERNEL);
        if (data == NULL)
            return -ENOMEM;
    
        *(__le16 *)&data[0] = cpu_to_le16(ctrl->bmHint);
        data[2] = ctrl->bFormatIndex;
        data[3] = ctrl->bFrameIndex;
        *(__le32 *)&data[4] = cpu_to_le32(ctrl->dwFrameInterval);
        *(__le16 *)&data[8] = cpu_to_le16(ctrl->wKeyFrameRate);
        *(__le16 *)&data[10] = cpu_to_le16(ctrl->wPFrameRate);
        *(__le16 *)&data[12] = cpu_to_le16(ctrl->wCompQuality);
        *(__le16 *)&data[14] = cpu_to_le16(ctrl->wCompWindowSize);
        *(__le16 *)&data[16] = cpu_to_le16(ctrl->wDelay);
        put_unaligned_le32(ctrl->dwMaxVideoFrameSize, &data[18]);
        put_unaligned_le32(ctrl->dwMaxPayloadTransferSize, &data[22]);
    
        if (size == 34) {
            put_unaligned_le32(ctrl->dwClockFrequency, &data[26]);
            data[30] = ctrl->bmFramingInfo;
            data[31] = ctrl->bPreferedVersion;
            data[32] = ctrl->bMinVersion;
            data[33] = ctrl->bMaxVersion;
        }
    
        pipe = (SET_CUR & 0x80) ? usb_rcvctrlpipe(myuvc_udev, 0)
                      : usb_sndctrlpipe(myuvc_udev, 0);
        type |= (SET_CUR & 0x80) ? USB_DIR_IN : USB_DIR_OUT;
    
        ret = usb_control_msg(myuvc_udev, pipe, SET_CUR, type, VS_PROBE_CONTROL << 8,
                0 << 8 | myuvc_streaming_intf, data, size, 5000);
    
        kfree(data);
        
        return (ret < 0) ? ret : 0;
        
    }
    
    
    /* 参考: uvc_v4l2_try_format ∕uvc_probe_video 
     *       uvc_set_video_ctrl(video, probe, 1)
     */
    static int myuvc_set_streaming_params(struct myuvc_streaming_control *ctrl)
    {
        __u8 *data;
        __u16 size;
        int ret;
    	__u8 type = USB_TYPE_CLASS | USB_RECIP_INTERFACE;
    	unsigned int pipe;
        
        size = uvc_version >= 0x0110 ? 34 : 26;
        data = kzalloc(size, GFP_KERNEL);
        if (data == NULL)
            return -ENOMEM;
    
        *(__le16 *)&data[0] = cpu_to_le16(ctrl->bmHint);
        data[2] = ctrl->bFormatIndex;
        data[3] = ctrl->bFrameIndex;
        *(__le32 *)&data[4] = cpu_to_le32(ctrl->dwFrameInterval);
        *(__le16 *)&data[8] = cpu_to_le16(ctrl->wKeyFrameRate);
        *(__le16 *)&data[10] = cpu_to_le16(ctrl->wPFrameRate);
        *(__le16 *)&data[12] = cpu_to_le16(ctrl->wCompQuality);
        *(__le16 *)&data[14] = cpu_to_le16(ctrl->wCompWindowSize);
        *(__le16 *)&data[16] = cpu_to_le16(ctrl->wDelay);
        put_unaligned_le32(ctrl->dwMaxVideoFrameSize, &data[18]);
        put_unaligned_le32(ctrl->dwMaxPayloadTransferSize, &data[22]);
    
        if (size == 34) {
            put_unaligned_le32(ctrl->dwClockFrequency, &data[26]);
            data[30] = ctrl->bmFramingInfo;
            data[31] = ctrl->bPreferedVersion;
            data[32] = ctrl->bMinVersion;
            data[33] = ctrl->bMaxVersion;
        }
    
        pipe = (SET_CUR & 0x80) ? usb_rcvctrlpipe(myuvc_udev, 0)
                      : usb_sndctrlpipe(myuvc_udev, 0);
        type |= (SET_CUR & 0x80) ? USB_DIR_IN : USB_DIR_OUT;
    
        ret = usb_control_msg(myuvc_udev, pipe, SET_CUR, type, VS_COMMIT_CONTROL << 8,
                0 << 8 | myuvc_streaming_intf, data, size, 5000);
    
        kfree(data);
        
        return (ret < 0) ? ret : 0;
        
    }
    
    static void myuvc_uninit_urbs(void)
    {
        int i;
        for (i = 0; i < MYUVC_URBS; ++i) {
            if (myuvc_queue.urb_buffer[i])
            {
                usb_buffer_free(myuvc_udev, myuvc_queue.urb_size, myuvc_queue.urb_buffer[i], myuvc_queue.urb_dma[i]);
                myuvc_queue.urb_buffer[i] = NULL;
            }
    
            if (myuvc_queue.urb[i])
            {
                usb_free_urb(myuvc_queue.urb[i]);
                myuvc_queue.urb[i] = NULL;
            }
        }
    }
    
    /* 参考: uvc_video_complete / uvc_video_decode_isoc */
    static void myuvc_video_complete(struct urb *urb)
    {
    	u8 *src;
        u8 *dest;
    	int ret, i;
        int len;
        int maxlen;
        int nbytes;
        struct myuvc_buffer *buf;
    	static int fid;
    	static int wake_cnt = 0;
    
        // 要修改影像資料，必須先宣告一個特別型態的指標變數，才能正確存取記憶體中的資料
        unsigned char *point_mem;
        static unsigned char *mem_temp = NULL;
    
        // 初始化暫存用的記憶體位置
        static unsigned int nArrayTemp_Size = 1000;
    
    	u8* mem;
    	int data_len;
        
    	switch (urb->status) {
    	case 0:
    		break;
    
    	default:
    		printk("Non-zero status (%d) in video "
    			"completion handler.\n", urb->status);
    		return;
    	}
    
        /* 如果irqqueue队列不空的话，从irqqueue队列中取出第1个缓冲区，用于存放urb的数据 */
    	if (!list_empty(&myuvc_queue.irqqueue))
    	{
    		buf = list_first_entry(&myuvc_queue.irqqueue, struct myuvc_buffer, irq);
    	}
    	else
    	{
    		/* 什么情况下会导致irqqueue队列为空呢?
    		 * usb设备填充数据太快，但是应用程序没能及时处理
    		 */
    		buf = NULL;
    	}
        
    	/* 开始处理urb中的每一个小包 */
    	for (i = 0; i < urb->number_of_packets; ++i) {
    		if (urb->iso_frame_desc[i].status < 0) {
    			//printk("USB isochronous frame "
    			//	"lost (%d).\n", urb->iso_frame_desc[i].status);
    			continue;
    		}
    
            src  = urb->transfer_buffer + urb->iso_frame_desc[i].offset;
    
    
            len = urb->iso_frame_desc[i].actual_length;
            /* 判断数据是否有效 */
            /* URB数据含义:
             * data[0] : 头部长度
             * data[1] : 错误状态
             */
            if (len < 2 || src[0] < 2 || src[0] > len)
                continue;
            
            /* Skip payloads marked with the error bit ("error frames"). */
            if (src[1] & UVC_STREAM_ERR) {
                //printk("Dropping payload (error bit set).\n");
                continue;
            }
    
    	    /* 根据ip2970/ip2977厂家提供的修改手册，如果想要支持ip2970/ip2977就必须
    		 * 添加如下代码 
    	     */
    	    if (myuvc_udev->descriptor.idVendor == 0x1B3B)
    	    {
    	        if ( len >= 16 ) // have data in buffer
    	        {
    	            // 資料必須從data[12]開始判斷，是因為前面的資料是封包專用
    	            if ( (src[12]==0xFF && src[13]==0xD8 && src[14]==0xFF) ||
    	                (src[12]==0xD8 && src[13]==0xFF && src[14]==0xC4)) 
    	            {
    	                if(last_fid)
    	                    fid &= ~UVC_STREAM_FID;
    	                else
    	                    fid |= UVC_STREAM_FID;
    	            }
    	        }
    	    }
    	    else
    	    {
    	    	fid = src[1] & UVC_STREAM_FID;
    	    }
    
    		/* Store the payload FID bit and return immediately when the buffer is
    		 * NULL.
    		 */
    		if (buf == NULL) {
    			last_fid = fid;
    			continue;
    		}
    
    		/* 根据FID判断当前帧的数据是否结束 */
    		/* VIDEOBUF_ACTIVE表示正在接收数据，buf->state!= VIDEOBUF_ACTIVE, 表示"之前还未接收数据"， 
    		 * 因此就是说即将接收数据
    		*/	
    		if (buf->state != VIDEOBUF_ACTIVE) {  		
    			if (fid == last_fid) {
    				/* 既然你刚开始接收数据, 那么FID应该是一个新的值,不应该等于原来的last_fid */
    				continue;
    			}
    
    			/* 表示开始接收第1个数据 */
    			buf->state = VIDEOBUF_ACTIVE;
    		}
    
    		/* fid表示当前的fid。
    		 * fid != last_fid 表示开始新一帧了，当前的buffer已经被填充完了。
    		 * 这个地方是从fid来判断是否一帧数据已经结束，下面还有从数据是否填充不下了来
    		 * 强制认为一帧数据已经结束
    		 */
    		if (fid != last_fid && buf->buf.bytesused != 0) {
    			buf->state = VIDEOBUF_DONE;
    
    			/* 从队列中删除, 唤醒进程 */
    	        list_del(&buf->irq);
    	        wake_up(&buf->wait);
    
    			mem = myuvc_queue.mem + buf->buf.m.offset;
    			data_len = buf->buf.bytesused;
    			//printk("wake_up %d : %s %d, start data: %02x %02x, end data: %02x %02x", wake_cnt++, __FUNCTION__, __LINE__, mem[0], mem[1], mem[data_len - 2], mem[data_len - 1]);
    
    			/* 取出下一个buf */
    			if (!list_empty(&myuvc_queue.irqqueue))
    			{
    				buf = list_first_entry(&myuvc_queue.irqqueue, struct myuvc_buffer, irq);
    			}
    			else
    			{
    				buf = NULL;
    			}
    			continue;
    		}
    		last_fid = fid;
    
            dest = myuvc_queue.mem + buf->buf.m.offset + buf->buf.bytesused;
    
            /* 除去头部后的数据长度 */
            len -= src[0];
    
            /* 缓冲区最多还能存多少数据 */
            maxlen = buf->buf.length - buf->buf.bytesused;
            nbytes = min(len, maxlen);
    
            /* 复制数据 */
            memcpy(dest, src + src[0], nbytes);
            buf->buf.bytesused += nbytes;
    
    	    /* ip2970/ip2977 */
    	    if (myuvc_udev->descriptor.idVendor == 0x1B3B)
    	    {
    	        if(mem_temp == NULL) {
    	            mem_temp = kmalloc(nArrayTemp_Size, GFP_KERNEL);
    	        }
    	        else if(nArrayTemp_Size <= nbytes){ // 當收到的資料長度大於上一次的資料長度，則重新分配所需的空間+
    	            kfree(mem_temp);
    	            nArrayTemp_Size += 500;
    	            mem_temp = kmalloc(nArrayTemp_Size, GFP_KERNEL);
    	        }
    	        memset(mem_temp, 0x00, nArrayTemp_Size);
    	        
    	        // 指向資料儲存的記憶體位置
    	        point_mem = (unsigned char *)dest;
    	        if( *(point_mem) == 0xD8 && *(point_mem + 1) == 0xFF && *(point_mem + 2) == 0xC4){
    	            memcpy( mem_temp + 1, point_mem, nbytes);
    	            mem_temp[0] = 0xFF;
    	            memcpy(point_mem, mem_temp, nbytes + 1);
    	        }
    	    }
    
    
    
            /* 判断一帧数据是否已经全部接收到 
    		 * 如果数据已经满了，就强制认为已经结束了
    		 */
            if (len > maxlen) {
                buf->state = VIDEOBUF_DONE;
            }
            
            /* Mark the buffer as done if the EOF marker is set. */
            if (src[1] & UVC_STREAM_EOF && buf->buf.bytesused != 0) {
               // printk("Frame complete (EOF found).\n");
                //if (len == 0)
               //     printk("EOF in empty payload.\n");
                buf->state = VIDEOBUF_DONE;
            }
    
    	    /* 当接收完一帧数据, 
    	     * 从irqqueue中删除这个缓冲区
    	     * 唤醒等待数据的进程 
    	     */
    	    if (buf->state == VIDEOBUF_DONE ||
    	        buf->state == VIDEOBUF_ERROR)
    	    {
    	        list_del(&buf->irq);
    	        wake_up(&buf->wait);
    
    			mem = myuvc_queue.mem + buf->buf.m.offset;
    			data_len = buf->buf.bytesused;
    			//printk("wake_up %d : %s %d, start data: %02x %02x, end data: %02x %02x", wake_cnt++, __FUNCTION__, __LINE__, mem[0], mem[1], mem[data_len - 2], mem[data_len - 1]);
    			
    			/* 取出下一个buf */
    			if (!list_empty(&myuvc_queue.irqqueue))
    			{
    				buf = list_first_entry(&myuvc_queue.irqqueue, struct myuvc_buffer, irq);
    			}
    			else
    			{
    				buf = NULL;
    			}
    	    }
    
    	}
    
    
        /* 再次提交URB */
    	if ((ret = usb_submit_urb(urb, GFP_ATOMIC)) < 0) {
    		printk("Failed to resubmit video URB (%d).\n", ret);
    	}
    }
    
    /* 参考: uvc_init_video_isoc */
    static int myuvc_alloc_init_urbs(void)
    {
    	u16 psize;
    	u32 size;
        int npackets;
        int i;
        int j;
    
        struct urb *urb;
    
    	psize = wMaxPacketSize; /* 实时传输端点一次能传输的最大字节数 */
    	size  = myuvc_params.dwMaxVideoFrameSize;  /* 一帧数据的最大长度 */
        npackets = DIV_ROUND_UP(size, psize);
        if (npackets > 32)
            npackets = 32;
    
        size = myuvc_queue.urb_size = psize * npackets;
        
        for (i = 0; i < MYUVC_URBS; ++i) {
            /* 1. 分配usb_buffers */
            
            myuvc_queue.urb_buffer[i] = usb_buffer_alloc(
                myuvc_udev, size,
                GFP_KERNEL | __GFP_NOWARN, &myuvc_queue.urb_dma[i]);
    
            /* 2. 分配urb */
    		myuvc_queue.urb[i] = usb_alloc_urb(npackets, GFP_KERNEL);
    
            if (!myuvc_queue.urb_buffer[i] || !myuvc_queue.urb[i])
            {
                myuvc_uninit_urbs();
                return -ENOMEM;
            }
    
        }
    
    
        /* 3. 设置urb */
        for (i = 0; i < MYUVC_URBS; ++i) {
            urb = myuvc_queue.urb[i];
            
            urb->dev = myuvc_udev;
            urb->context = NULL;
            urb->pipe = usb_rcvisocpipe(myuvc_udev,myuvc_bEndpointAddress);
            urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP;
            urb->interval = 1;
            urb->transfer_buffer = myuvc_queue.urb_buffer[i];
            urb->transfer_dma = myuvc_queue.urb_dma[i];
            urb->complete = myuvc_video_complete;
            urb->number_of_packets = npackets;
            urb->transfer_buffer_length = size;
            
            for (j = 0; j < npackets; ++j) {
                urb->iso_frame_desc[j].offset = j * psize;
                urb->iso_frame_desc[j].length = psize;
            }
        
        }
        
        return 0;
    }
    
    /* A11 启动传输 
     * 参考: uvc_video_enable(video, 1):
     *           uvc_commit_video
     *           uvc_init_video
     */
    static int myuvc_vidioc_streamon(struct file *file, void *priv, enum v4l2_buf_type i)
    {
        int ret;
        
        /* 1. 向USB摄像头设置参数: 比如使用哪个format, 使用这个format下的哪个frame(分辨率) 
         * 参考: uvc_set_video_ctrl / uvc_get_video_ctrl
         * 1.1 根据一个结构体uvc_streaming_control设置数据包: 可以手工设置,也可以读出后再修改
         * 1.2 调用usb_control_msg发出数据包
         */
    
        /* a. 测试参数 */
        ret = myuvc_try_streaming_params(&myuvc_params);
        printk("myuvc_try_streaming_params ret = %d\n", ret);
    
        /* b. 取出参数 */
        ret = myuvc_get_streaming_params(&myuvc_params);
        printk("myuvc_get_streaming_params ret = %d\n", ret);
    
        /* c. 设置参数 */
        ret = myuvc_set_streaming_params(&myuvc_params);
        printk("myuvc_set_streaming_params ret = %d\n", ret);
        
        myuvc_print_streaming_params(&myuvc_params);
    
        /* d. 设置VideoStreaming Interface所使用的setting
         * d.1 从myuvc_params确定带宽
         * d.2 根据setting的endpoint能传输的wMaxPacketSize
         *     找到能满足该带宽的setting
         */
        /* 手工确定:
         * bandwidth = myuvc_params.dwMaxPayloadTransferSize = 800
         * 观察lsusb -v -d 0x1e4e:的结果:
         *                wMaxPacketSize     0x0320  1x 800 bytes
         * bAlternateSetting       5
         */
        usb_set_interface(myuvc_udev, myuvc_streaming_intf, myuvc_streaming_bAlternateSetting);
        
        /* 2. 分配设置URB */
        ret = myuvc_alloc_init_urbs();
        if (ret)
            printk("myuvc_alloc_init_urbs err : ret = %d\n", ret);
    
        /* 3. 提交URB以接收数据 */
    	for (i = 0; i < MYUVC_URBS; ++i) {
    		if ((ret = usb_submit_urb(myuvc_queue.urb[i], GFP_KERNEL)) < 0) {
    			printk("Failed to submit URB %u (%d).\n", i, ret);
    			myuvc_uninit_urbs();
    			return ret;
    		}
    	}
        
    	return 0;
    }
    
    /* A13 APP通过poll/select确定有数据后, 把缓存从队列中取出来
     * 参考: uvc_dequeue_buffer
     */
    static int myuvc_vidioc_dqbuf(struct file *file, void *priv, struct v4l2_buffer *v4l2_buf)
    {
        /* APP发现数据就绪后, 从mainqueue里取出这个buffer */
    
        struct myuvc_buffer *buf;
        int ret = 0;
    
    	if (list_empty(&myuvc_queue.mainqueue)) {
    		ret = -EINVAL;
    		goto done;
    	}
        
    	buf = list_first_entry(&myuvc_queue.mainqueue, struct myuvc_buffer, stream);
    
    	switch (buf->state) {
    	case VIDEOBUF_ERROR:
    		ret = -EIO;
    	case VIDEOBUF_DONE:
    		buf->state = VIDEOBUF_IDLE;
    		break;
    
    	case VIDEOBUF_IDLE:
    	case VIDEOBUF_QUEUED:
    	case VIDEOBUF_ACTIVE:
    	default:
    		ret = -EINVAL;
    		goto done;
    	}
    
    	list_del(&buf->stream);
    	memcpy(v4l2_buf, &buf->buf, sizeof *v4l2_buf);
    	
    done:
    	return ret;
    }
    
    /*
     * A14 之前已经通过mmap映射了缓存, APP可以直接读数据
     * A15 再次调用myuvc_vidioc_qbuf把缓存放入队列
     * A16 poll...
     */
    
    /* A17 停止 
     * 参考 : uvc_video_enable(video, 0)
     */
    static int myuvc_vidioc_streamoff(struct file *file, void *priv, enum v4l2_buf_type t)
    {
    	struct urb *urb;
    	unsigned int i;
    
        /* 1. kill URB */
    	for (i = 0; i < MYUVC_URBS; ++i) {
    		if ((urb = myuvc_queue.urb[i]) == NULL)
    			continue;
    		usb_kill_urb(urb);
    	}
    
        /* 2. free URB */
        myuvc_uninit_urbs();
    
        /* 3. 设置VideoStreaming Interface为setting 0 */
        usb_set_interface(myuvc_udev, myuvc_streaming_intf, 0);
        
        return 0;
    }
    
        /* Control handling */
    
    
    /* Extract the bit string specified by mapping->offset and mapping->size
     * from the little-endian data stored at 'data' and return the result as
     * a signed 32bit integer. Sign extension will be performed if the mapping
     * references a signed data type.
     */
    static __s32 myuvc_get_le_value(const __u8 *data)
    {
        int bits = 16;
        int offset = 0;
        __s32 value = 0;
        __u8 mask;
    
        data += offset / 8;
        offset &= 7;
        mask = ((1LL << bits) - 1) << offset;
    
        for (; bits > 0; data++) {
            __u8 byte = *data & mask;
            value |= offset > 0 ? (byte >> offset) : (byte << (-offset));
            bits -= 8 - (offset > 0 ? offset : 0);
            offset -= 8;
            mask = (1 << bits) - 1;
        }
    
        /* Sign-extend the value if needed. */
        value |= -(value & (1 << (16 - 1)));
    
        return value;
    }
    
    /* Set the bit string specified by mapping->offset and mapping->size
     * in the little-endian data stored at 'data' to the value 'value'.
     */
    static void myuvc_set_le_value(__s32 value, __u8 *data)
    {
    	int bits = 16;
    	int offset = 0;
    	__u8 mask;
    
    	data += offset / 8;
    	offset &= 7;
    
    	for (; bits > 0; data++) {
    		mask = ((1LL << bits) - 1) << offset;
    		*data = (*data & ~mask) | ((value << offset) & mask);
    		value >>= offset ? offset : 8;
    		bits -= 8 - offset;
    		offset = 0;
    	}
    }
        
    
    
    /* 参考:uvc_query_v4l2_ctrl */    
    int myuvc_vidioc_queryctrl (struct file *file, void *fh,
                    struct v4l2_queryctrl *ctrl)
    {
    	__u8 type = USB_TYPE_CLASS | USB_RECIP_INTERFACE;
    	unsigned int pipe;
        int ret;
        u8 data[2];
    
        if (ctrl->id != V4L2_CID_BRIGHTNESS)
            return -EINVAL;
        
    	memset(ctrl, 0, sizeof *ctrl);
    	ctrl->id   = V4L2_CID_BRIGHTNESS;
    	ctrl->type = V4L2_CTRL_TYPE_INTEGER;
    	strcpy(ctrl->name, "MyUVC_BRIGHTNESS");
    	ctrl->flags = 0;
    
    	pipe = usb_rcvctrlpipe(myuvc_udev, 0);
    	type |= USB_DIR_IN;
    
        /* 发起USB传输确定这些值 */
    	ret = usb_control_msg(myuvc_udev, pipe, GET_MIN, type, PU_BRIGHTNESS_CONTROL << 8,
    			ProcessingUnitID << 8 | myuvc_control_intf, data, 2, 5000);
        if (ret != 2)
            return -EIO;
    	ctrl->minimum = myuvc_get_le_value(data);	/* Note signedness */
    
    
    	ret = usb_control_msg(myuvc_udev, pipe, GET_MAX, type,  PU_BRIGHTNESS_CONTROL << 8,
    			ProcessingUnitID << 8 | myuvc_control_intf, data, 2, 5000);
        if (ret != 2)
            return -EIO;
    	ctrl->maximum = myuvc_get_le_value(data);	/* Note signedness */
    
    	ret = usb_control_msg(myuvc_udev, pipe, GET_RES, type, PU_BRIGHTNESS_CONTROL << 8,
    			 ProcessingUnitID << 8 | myuvc_control_intf, data, 2, 5000);
        if (ret != 2)
            return -EIO;
    	ctrl->step = myuvc_get_le_value(data);	/* Note signedness */
    
    	ret = usb_control_msg(myuvc_udev, pipe, GET_DEF, type, PU_BRIGHTNESS_CONTROL << 8,
    			ProcessingUnitID << 8 | myuvc_control_intf, data, 2, 5000);
        if (ret != 2)
            return -EIO;
    	ctrl->default_value = myuvc_get_le_value(data);	/* Note signedness */
    
        printk("Brightness: min =%d, max = %d, step = %d, default = %d\n", ctrl->minimum, ctrl->maximum, ctrl->step, ctrl->default_value);
        
        return 0;
    }
    
    /* 参考 : uvc_ctrl_get */
    int myuvc_vidioc_g_ctrl (struct file *file, void *fh,
                    struct v4l2_control *ctrl)
    {
    	__u8 type = USB_TYPE_CLASS | USB_RECIP_INTERFACE;
    	unsigned int pipe;
        int ret;
        u8 data[2];
        
        if (ctrl->id != V4L2_CID_BRIGHTNESS)
            return -EINVAL;
    
    	pipe = usb_rcvctrlpipe(myuvc_udev, 0);
    	type |= USB_DIR_IN;
    
    	ret = usb_control_msg(myuvc_udev, pipe, GET_CUR, type, PU_BRIGHTNESS_CONTROL << 8,
    			ProcessingUnitID << 8 | myuvc_control_intf, data, 2, 5000);
        if (ret != 2)
            return -EIO;
    	ctrl->value = myuvc_get_le_value(data);	/* Note signedness */
        
        return 0;
    }
    
    /* 参考: uvc_ctrl_set/uvc_ctrl_commit */
    int myuvc_vidioc_s_ctrl (struct file *file, void *fh,
                    struct v4l2_control *ctrl)
    {
        __u8 type = USB_TYPE_CLASS | USB_RECIP_INTERFACE;
        unsigned int pipe;
        int ret;
        u8 data[2];
        
        if (ctrl->id != V4L2_CID_BRIGHTNESS)
            return -EINVAL;
    
        myuvc_set_le_value(ctrl->value, data);
    
        pipe = usb_sndctrlpipe(myuvc_udev, 0);
        type |= USB_DIR_OUT;
    
        ret = usb_control_msg(myuvc_udev, pipe, SET_CUR, type, PU_BRIGHTNESS_CONTROL << 8,
                ProcessingUnitID  << 8 | myuvc_control_intf, data, 2, 5000);
        if (ret != 2)
            return -EIO;
        
        return 0;
    }
    
    
    
    static const struct v4l2_ioctl_ops myuvc_ioctl_ops = {
            // 表示它是一个摄像头设备
            .vidioc_querycap      = myuvc_vidioc_querycap,
    
            /* 用于列举、获得、测试、设置摄像头的数据的格式 */
            .vidioc_enum_fmt_vid_cap  = myuvc_vidioc_enum_fmt_vid_cap,
            .vidioc_g_fmt_vid_cap     = myuvc_vidioc_g_fmt_vid_cap,
            .vidioc_try_fmt_vid_cap   = myuvc_vidioc_try_fmt_vid_cap,
            .vidioc_s_fmt_vid_cap     = myuvc_vidioc_s_fmt_vid_cap,
            
            /* 缓冲区操作: 申请/查询/放入队列/取出队列 */
            .vidioc_reqbufs       = myuvc_vidioc_reqbufs,
            .vidioc_querybuf      = myuvc_vidioc_querybuf,
            .vidioc_qbuf          = myuvc_vidioc_qbuf,
            .vidioc_dqbuf         = myuvc_vidioc_dqbuf,
    
            /* 查询/获得/设置属性 */
            .vidioc_queryctrl     = myuvc_vidioc_queryctrl,
            .vidioc_g_ctrl        = myuvc_vidioc_g_ctrl,
            .vidioc_s_ctrl        = myuvc_vidioc_s_ctrl,
            
            // 启动/停止
            .vidioc_streamon      = myuvc_vidioc_streamon,
            .vidioc_streamoff     = myuvc_vidioc_streamoff,   
    };
    
    /* A1 */
    static int myuvc_open(struct file *file)
    {
    	return 0;
    }
    
    static void myuvc_vm_open(struct vm_area_struct *vma)
    {
    	struct myuvc_buffer *buffer = vma->vm_private_data;
    	buffer->vma_use_count++;
    }
    
    static void myuvc_vm_close(struct vm_area_struct *vma)
    {
    	struct myuvc_buffer *buffer = vma->vm_private_data;
    	buffer->vma_use_count--;
    }
    
    static struct vm_operations_struct myuvc_vm_ops = {
    	.open		= myuvc_vm_open,
    	.close		= myuvc_vm_close,
    };
    
    
    /* A9 把缓存映射到APP的空间,以后APP就可以直接操作这块缓存 
     * 参考: uvc_v4l2_mmap
     */
    static int myuvc_mmap(struct file *file, struct vm_area_struct *vma)
    {
        struct myuvc_buffer *buffer;
        struct page *page;
        unsigned long addr, start, size;
        unsigned int i;
        int ret = 0;
    
        start = vma->vm_start;
        size = vma->vm_end - vma->vm_start;
    
        /* 应用程序调用mmap函数时, 会传入offset参数
         * 根据这个offset找出指定的缓冲区
         */
        for (i = 0; i < myuvc_queue.count; ++i) {
            buffer = &myuvc_queue.buffer[i];
            if ((buffer->buf.m.offset >> PAGE_SHIFT) == vma->vm_pgoff)
                break;
        }
    
        if (i == myuvc_queue.count || size != myuvc_queue.buf_size) {
            ret = -EINVAL;
            goto done;
        }
    
        /*
         * VM_IO marks the area as being an mmaped region for I/O to a
         * device. It also prevents the region from being core dumped.
         */
        vma->vm_flags |= VM_IO;
    
        /* 根据虚拟地址找到缓冲区对应的page构体 */
        addr = (unsigned long)myuvc_queue.mem + buffer->buf.m.offset;
        while (size > 0) {
            page = vmalloc_to_page((void *)addr);
    
            /* 把page和APP传入的虚拟地址挂构 */
            if ((ret = vm_insert_page(vma, start, page)) < 0)
                goto done;
    
            start += PAGE_SIZE;
            addr += PAGE_SIZE;
            size -= PAGE_SIZE;
        }
    
        vma->vm_ops = &myuvc_vm_ops;
        vma->vm_private_data = buffer;
        myuvc_vm_open(vma);
    
    done:
        return ret;
    }
    
    /* A12 APP调用POLL/select来确定缓存是否就绪(有数据) 
     * 参考 : uvc_v4l2_poll
     */
    static unsigned int myuvc_poll(struct file *file, struct poll_table_struct *wait)
    {
    	struct myuvc_buffer *buf;
    	unsigned int mask = 0;
        
        /* 从mainqueuq中取出第1个缓冲区 */
    
        /*判断它的状态, 如果未就绪, 休眠 */
    
        if (list_empty(&myuvc_queue.mainqueue)) {
            mask |= POLLERR;
            goto done;
        }
        
        buf = list_first_entry(&myuvc_queue.mainqueue, struct myuvc_buffer, stream);
    
        poll_wait(file, &buf->wait, wait);
        if (buf->state == VIDEOBUF_DONE ||
            buf->state == VIDEOBUF_ERROR)
            mask |= POLLIN | POLLRDNORM;
        
    done:
        return mask;
    }
    
    /* A18 关闭 */
    static int myuvc_vidioc_streamoff(struct file *file, void *priv, enum v4l2_buf_type t);
    static int myuvc_close(struct file *file)
    {
        myuvc_vidioc_streamoff(NULL, NULL, 0);
    	return 0;
    }
    
    static const struct v4l2_file_operations myuvc_fops = {
    	.owner		= THIS_MODULE,
        .open       = myuvc_open,
        .release    = myuvc_close,
        .mmap       = myuvc_mmap,
        .ioctl      = video_ioctl2, /* V4L2 ioctl handler */
        .poll       = myuvc_poll,
    };
    
    static void myuvc_release(struct video_device *vdev)
    {
    }
    
    
    static int myuvc_probe(struct usb_interface *intf,
    		     const struct usb_device_id *id)
    {
        static int cnt = 0;
    	struct usb_device *dev = interface_to_usbdev(intf);
    	int ret;
    
        myuvc_udev = dev;
    
        printk("myuvc_probe : cnt = %d\n", cnt++);
    
        if (cnt == 1)
        {
            myuvc_control_intf = intf->cur_altsetting->desc.bInterfaceNumber;
        }
        else if (cnt == 2)
        {
            myuvc_streaming_intf = intf->cur_altsetting->desc.bInterfaceNumber;
        }
    
        if (cnt == 2)
        {
            /* 1. 分配一个video_device结构体 */
            myuvc_vdev = video_device_alloc();
    
            /* 2. 设置 */
            /* 2.1 */
            myuvc_vdev->release = myuvc_release;
            
            /* 2.2 */
            myuvc_vdev->fops    = &myuvc_fops;
            
            /* 2.3 */
            myuvc_vdev->ioctl_ops = &myuvc_ioctl_ops;
    
            /* 3. 注册 */
            video_register_device(myuvc_vdev, VFL_TYPE_GRABBER, -1);
    
    		/* 为了确定带宽,使用哪一个setting */
    	    /* a. 测试参数 */
    	    ret = myuvc_try_streaming_params(&myuvc_params);
    	    printk("myuvc_try_streaming_params ret = %d\n", ret);
    
    	    /* b. 取出参数 */
    	    ret = myuvc_get_streaming_params(&myuvc_params);
    	    printk("myuvc_get_streaming_params ret = %d\n", ret);
    
    	    /* c. 设置参数 */
    	    ret = myuvc_set_streaming_params(&myuvc_params);
    	    printk("myuvc_set_streaming_params ret = %d\n", ret);
    	    
    	    myuvc_print_streaming_params(&myuvc_params);
    
        }
        
        
        return 0;
    }
    
    static void myuvc_disconnect(struct usb_interface *intf)
    {
        static int cnt = 0;
        printk("myuvc_disconnect : cnt = %d\n", cnt++);
    
        if (cnt == 2)
        {
            video_unregister_device(myuvc_vdev);
            video_device_release(myuvc_vdev);
        }
        
    }
    
    static struct usb_device_id myuvc_ids[] = {
    	/* Generic USB Video Class */
    	{ USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, 0) },  /* VideoControl Interface */
        { USB_INTERFACE_INFO(USB_CLASS_VIDEO, 2, 0) },  /* VideoStreaming Interface */
    	{}
    };
    
    /* 1. 分配usb_driver */
    /* 2. 设置 */
    static struct usb_driver myuvc_driver = {
        .name       = "myuvc",
        .probe      = myuvc_probe,
        .disconnect = myuvc_disconnect,
        .id_table   = myuvc_ids,
    };
    
    static int myuvc_init(void)
    {
        /* 3. 注册 */
        usb_register(&myuvc_driver);
        return 0;
    }
    
    static void myuvc_exit(void)
    {
        usb_deregister(&myuvc_driver);
    }
    
    module_init(myuvc_init);
    module_exit(myuvc_exit);
    
    MODULE_LICENSE("GPL");