OpenProtocl 具体用法

版权声明：本文全部是胡说八道，如果你喜欢，可随意转载 https://blog.csdn.net/robinsongsog/article/details/82114570

/**
  Check whether USB keyboard driver supports this device.

  @param  This                   The USB keyboard driver binding protocol.
  @param  Controller             The controller handle to check.
  @param  RemainingDevicePath    The remaining device path.

  @retval EFI_SUCCESS            The driver supports this controller.
  @retval other                  This device isn't supported.

**/
EFI_STATUS
EFIAPI
USBKeyboardDriverBindingSupported (
  IN EFI_DRIVER_BINDING_PROTOCOL    *This,
  IN EFI_HANDLE                     Controller,
  IN EFI_DEVICE_PATH_PROTOCOL       *RemainingDevicePath
  )
{
  EFI_STATUS          Status;
  EFI_USB_IO_PROTOCOL *UsbIo;

  //
  // Check if USB I/O Protocol is attached on the controller handle.
  //
  Status = gBS->OpenProtocol (
                  Controller,
                  &gEfiUsbIoProtocolGuid,
                  (VOID **) &UsbIo,
                  This->DriverBindingHandle,
                  Controller,
                  EFI_OPEN_PROTOCOL_BY_DRIVER
                  );
  if (EFI_ERROR (Status)) {
    return Status;
  }

  //
  // Use the USB I/O Protocol interface to check whether Controller is
  // a keyboard device that can be managed by this driver.
  //
  Status = EFI_SUCCESS;

  if (!IsUSBKeyboard (UsbIo)) {
    Status = EFI_UNSUPPORTED;
  }

  gBS->CloseProtocol (
         Controller,
         &gEfiUsbIoProtocolGuid,
         This->DriverBindingHandle,
         Controller
         );

  return Status;
}

如何确认，找到的是不是我们想要的protocol , 可以事后，做一些判断：

比如：

  //
  // Use the USB I/O Protocol interface to check whether Controller is
  // a keyboard device that can be managed by this driver.
  //
  Status = EFI_SUCCESS;

  if (!IsUSBKeyboard (UsbIo)) {
    Status = EFI_UNSUPPORTED;
  }

UsbIo 是打开后得到的结果，用这个得到的结果拿出来测测

/**
  Uses USB I/O to check whether the device is a USB keyboard device.

  @param  UsbIo    Pointer to a USB I/O protocol instance.

  @retval TRUE     Device is a USB keyboard device.
  @retval FALSE    Device is a not USB keyboard device.

**/
BOOLEAN
IsUSBKeyboard (
  IN  EFI_USB_IO_PROTOCOL       *UsbIo
  )
{
  EFI_STATUS                    Status;
  EFI_USB_INTERFACE_DESCRIPTOR  InterfaceDescriptor;

  //
  // Get the default interface descriptor
  //
  Status = UsbIo->UsbGetInterfaceDescriptor (
                    UsbIo,
                    &InterfaceDescriptor
                    );

  if (EFI_ERROR (Status)) {
    return FALSE;
  }

  if (InterfaceDescriptor.InterfaceClass == CLASS_HID &&
      InterfaceDescriptor.InterfaceSubClass == SUBCLASS_BOOT &&
      InterfaceDescriptor.InterfaceProtocol == PROTOCOL_KEYBOARD
      ) {
    return TRUE;
  }

  return FALSE;
}