[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.註冊usb設備驅動(usb攝像頭設備)
if (result == 0) //註冊失敗
printk(KERN_INFO DRIVER_DESC " (" DRIVER_VERSION ")\n");
return result;
}
3.註冊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設備名字爲其產品名
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註冊視頻設備
goto error;
/* Save our data pointer in the interface data. */
usb_set_intfdata(intf, dev); //設置uvc設備爲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(掛着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設備狀態標誌
struct input_dev *input; //輸入設備
char input_phys[64]; //輸入設備設備節點路徑
};