uvc摄像头代码解析2

1.uvc驱动模块入口

[cpp]  

module_init(uvc_init);  //1.模块入口  

2.初始化函数

[cpp]  

static int __init uvc_init(void)    // 2.初始化函数  

{  

    int result;  

    result = usb_register(&uvc_driver.driver);  // 3.注册usb设备驱动(usb摄像头设备)  

    if (result == 0)    //注册失败  

        printk(KERN_INFO DRIVER_DESC " (" DRIVER_VERSION ")\n");  

    return result;  

}  

3.注册usb设备驱动(usb摄像头设备)

3.1 usb摄像头驱动

[cpp]  

struct uvc_driver uvc_driver = {    // 3.1 usb摄像头设备  

    .driver = {  

        .name       = "uvcvideo",  

        .probe      = uvc_probe,    // 4. probe方法  

        .disconnect = uvc_disconnect,  

        .suspend    = uvc_suspend,  

        .resume     = uvc_resume,  

        .reset_resume   = uvc_reset_resume,  

        .id_table   = uvc_ids,      //3.2 支持的设备id列表  

        .supports_autosuspend = 1,  

    },  

};  

3.2 支持的设备id列表uvc_ids

[cpp]  

static struct usb_device_id uvc_ids[] = {  

    /* Genius eFace 2025 */  

    { .match_flags      = USB_DEVICE_ID_MATCH_DEVICE | USB_DEVICE_ID_MATCH_INT_INFO,  

      .idVendor     = 0x0458,  

      .idProduct        = 0x706e,  

      .bInterfaceClass  = USB_CLASS_VIDEO,  //uvc接口类 0x0e  

      .bInterfaceSubClass   = 1,  

      .bInterfaceProtocol   = 0,  

      .driver_info      = UVC_QUIRK_PROBE_MINMAX },  

    ...  

    ...  

    ...  

    /* 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 */   //通用usb视频类  

    { USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, 0) },  //匹配方法:uvc类  

    {}  

};  

4.probe方法

[cpp]  

static int uvc_probe(struct usb_interface *intf,const struct usb_device_id *id)  

{  

    struct usb_device *udev = interface_to_usbdev(intf);    //通过usb接口获取usb设备  

    struct uvc_device *dev; //声明uvc设备  

    int ret;  

    if (id->idVendor && id->idProduct)    //有厂商id和商品id(知名设备)  

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

    else                                //通用uvc设备  

        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)   //分配uvc设备内存  

        return -ENOMEM;  

    INIT_LIST_HEAD(&dev->entities);  //初始化entities(实体)链表 Terminal或Unit  

    INIT_LIST_HEAD(&dev->chains);    //初始化chains(链)链表  

    INIT_LIST_HEAD(&dev->streams);   //初始化streams(视频流)链表  

    atomic_set(&dev->nstreams, 0);  

    atomic_set(&dev->users, 0);  

    atomic_set(&dev->nmappings, 0);  

    dev->udev = usb_get_dev(udev);   //捆绑usb设备,并增加其引用计数  

    dev->intf = usb_get_intf(intf);  //捆绑usb接口,并增加其引用计数  

    dev->intfnum = intf->cur_altsetting->desc.bInterfaceNumber;    //获取usb接口描述符接口数  

    dev->quirks = (uvc_quirks_param == -1) ? id->driver_info : uvc_quirks_param;  

    if (udev->product != NULL)   //存在产品名  

        strlcpy(dev->name, udev->product, sizeof dev->name);   //设置uvc设备名字为其产品名  

    else                        //通用的uvc设备名  

        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) {    //-->5 uvc解析usb视频类控制描述符  

        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 (dev->quirks != id->driver_info) {  

        uvc_printk(KERN_INFO, "Forcing device quirks to 0x%x by module parameter for testing purpose.\n", dev->quirks);  

        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)   //8.uvc初始化控制  

        goto error;  

    /* Scan the device for video chains. */  

    if (uvc_scan_device(dev) < 0)    //10.uvc扫描视频链  

        goto error;  

    /* Register video devices. */  

    if (uvc_register_chains(dev) < 0)    //11.uvc注册视频设备  

        goto error;  

    /* Save our data pointer in the interface data. */  

    usb_set_intfdata(intf, dev);    //设置uvc设备为usb接口的数据  

    /* Initialize the interrupt URB. */  

    if ((ret = uvc_status_init(dev)) < 0) {  //12 uvc设备状态初始化  

        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");  

    usb_enable_autosuspend(udev);   //使能自动挂起  

    return 0;  

error:  

    uvc_unregister_video(dev);  

    return -ENODEV;  

}  

4.1 uvc设备结构体

[cpp]  

struct uvc_device {  

    struct usb_device *udev;    //usb设备指针  

    struct usb_interface *intf; //usb接口指针  

    unsigned long warnings;  

    __u32 quirks;  

    int intfnum;    //接口数  

    char name[32];  //设备名  

    enum uvc_device_state state;    //uvc设备状态  

    atomic_t users;  

    atomic_t nmappings;  

    /* Video control interface */  

    __u16 uvc_version;  //UVC协议版本  

    __u32 clock_frequency;  //时钟频率  

    struct list_head entities;  //uvc实体链表头(挂着uvc设备的Terminal和Unit)  

    struct list_head chains;    //uvc视频链链表头  

    /* Video Streaming interfaces */  

    struct list_head streams;   //uvc视频流链表头  

    atomic_t nstreams;//uvc视频流个数  

    /* Status Interrupt Endpoint */  

    struct usb_host_endpoint *int_ep;   //usb_host_endpoint对象  

    struct urb *int_urb;    //中断urb  

    __u8 *status;   //uvc设备状态标志  

    struct input_dev *input;    //输入设备  

    char input_phys[64];    //输入设备设备节点路径  

};