uvc攝像頭代碼解析2

1.uvc驅動模塊入口 [cpp]   module_init(uvc_init);  //1.模塊入口   2.初始化函數 [cpp]   static int __init uvc_init(void)    // 2.初始化函數   {       int result;       result = usb_register(&uvc_driver.driver);  // 3.注冊usb設備驅動(usb攝像頭設備)       if (result == 0)    //注冊失敗           printk(KERN_INFO DRIVER_DESC " (" DRIVER_VERSION ")\n");       return result;   }   3.注冊usb設備驅動(usb攝像頭設備) 3.1 usb攝像頭驅動 [cpp]   struct uvc_driver uvc_driver = {    // 3.1 usb攝像頭設備       .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 支持的設備id列表           .supports_autosuspend = 1,       },   };   3.2 支持的設備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接口類 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視頻類       { USB_INTERFACE_INFO(USB_CLASS_VIDEO, 1, 0) },  //匹配方法:uvc類       {}   };   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);    //通過usb接口獲取usb設備       struct uvc_device *dev; //聲明uvc設備       int ret;       if (id->idVendor && id->idProduct)    //有廠商id和商品id(知名設備)           uvc_trace(UVC_TRACE_PROBE, "Probing known UVC device %s (%04x:%04x)\n", udev->devpath, id->idVendor,id->idProduct);       else                                //通用uvc設備           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設備內存           return -ENOMEM;       INIT_LIST_HEAD(&dev->entities);  //初始化entities(實體)鏈表 Terminal或Unit       INIT_LIST_HEAD(&dev->chains);    //初始化chains(鏈)鏈表       INIT_LIST_HEAD(&dev->streams);   //初始化streams(視頻流)鏈表       atomic_set(&dev->nstreams, 0);       atomic_set(&dev->users, 0);       atomic_set(&dev->nmappings, 0);       dev->udev = usb_get_dev(udev);   //捆綁usb設備,並增加其引用計數       dev->intf = usb_get_intf(intf);  //捆綁usb接口,並增加其引用計數       dev->intfnum = intf->cur_altsetting->desc.bInterfaceNumber;    //獲取usb接口描述符接口數       dev->quirks = (uvc_quirks_param == -1) ? id->driver_info : uvc_quirks_param;       if (udev->product != NULL)   //存在產品名           strlcpy(dev->name, udev->product, sizeof dev->name);   //設置uvc設備名字為其產品名       else                        //通用的uvc設備名           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視頻類控制描述符           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掃描視頻鏈           goto error;       /* Register video devices. */       if (uvc_register_chains(dev) < 0)    //11.uvc注冊視頻設備           goto error;       /* Save our data pointer in the interface data. */       usb_set_intfdata(intf, dev);    //設置uvc設備為usb接口的數據       /* Initialize the interrupt URB. */       if ((ret = uvc_status_init(dev)) < 0) {  //12 uvc設備狀態初始化           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);   //使能自動掛起       return 0;   error:       uvc_unregister_video(dev);       return -ENODEV;   }   4.1 uvc設備結構體 [cpp]   struct uvc_device {       struct usb_device *udev;    //usb設備指針       struct usb_interface *intf; //usb接口指針       unsigned long warnings;       __u32 quirks;       int intfnum;    //接口數       char name[32];  //設備名       enum uvc_device_state state;    //uvc設備狀態       atomic_t users;       atomic_t nmappings;       /* Video control interface */       __u16 uvc_version;  //UVC協議版本       __u32 clock_frequency;  //時鐘頻率       struct list_head entities;  //uvc實體鏈表頭(掛著uvc設備的Terminal和Unit)       struct list_head chains;    //uvc視頻鏈鏈表頭       /* Video Streaming interfaces */       struct list_head streams;   //uvc視頻流鏈表頭       atomic_t nstreams;//uvc視頻流個數       /* Status Interrupt Endpoint */       struct usb_host_endpoint *int_ep;   //usb_host_endpoint對象       struct urb *int_urb;    //中斷urb       __u8 *status;   //uvc設備狀態標志       struct input_dev *input;    //輸入設備       char input_phys[64];    //輸入設備設備節點路徑   };