使用定义好的ops接口函数返回为-RT_ENOSYS函数为空的错误。

发布于 2022-01-12 17:08:36 浏览：769 订阅该版

```c
int rt_device_hid_registr(const char *name,void *user_data)
{
		struct rt_device *device;

_usb_hid.parent.type		= RT_Device_Class_USBDevice;
		_usb_hid.parent.rx_indicate = RT_NULL;
		_usb_hid.parent.tx_complete = RT_NULL;
		
#ifdef RT_USING_DEVICE_OPS
		_usb_hid.parent.ops 		= &pin_ops;
#else
		device->open 				= rt_usb_hid_open;
		device->close               = rt_usb_hid_close;
		device->read 				= rt_usb_hid_read;
		device->write               = rt_usb_hid_write;
#endif
		_usb_hid.parent.user_data	= user_data;

device = &_usb_hid.parent;
		
		/* register a character device */
		rt_device_register(device, name, RT_DEVICE_FLAG_RDWR);
		
		return 0;

}
```
我这样注册一个自定义的HID设备，系统提示注册成功。
调用`hid_device = rt_device_find("usbh");`函数也能找到这个设备。
但是在通过系统函数如`rt_device_open（）`或者`rt_device_write（）`函数，返回为空，也根本不能进入到我定义的函数中。

我自己定义的测试函数如下：
```c
static rt_err_t rt_usb_hid_open(struct rt_device *dev, rt_uint16_t oflag)
{
	if (oflag == RT_DEVICE_FLAG_RDWR)
	{
		rt_kprintf("usb-hid  open ok!!!");
	}
	else
	{
		rt_kprintf("usb-hid  open err!!!");
	}

return RT_EOK;
}
static rt_err_t rt_usb_hid_close(struct rt_device *dev)
{
	rt_kprintf("usb-hid  close ok!!!");
	return RT_EOK;
}

static rt_size_t rt_usb_hid_read( struct rt_device *dev,
                                      rt_off_t          pos,
                                      void             *buffer,
                                      rt_size_t         size)
{
	//struct rt_usb_hid_device *hid;

RT_ASSERT(dev != RT_NULL);
	if (size == 0)
	{
		return RT_ERROR;
	}

//hid = (struct rt_usb_hid_device *)dev;

rt_kprintf("usb-hid  read ok!!!");
	
	return RT_EOK;

}

static rt_size_t rt_usb_hid_write( struct rt_device *dev,
                                 	    rt_off_t          pos,
                                 	    const void       *buffer,
                                        rt_size_t         size)
{
	//struct rt_usb_hid_device *hid;

RT_ASSERT(dev != RT_NULL);
	if (size == 0)
	{
		return RT_ERROR;
	}

//hid = (struct rt_usb_hid_device *)dev;

USB_CopyUserToPMABuf((rt_uint8_t *)buffer,ENDP2_TXADDR,size);
    USB_SetEpTxCnt(ENDP2,64);
    USB_SetEpTxValid(ENDP2);

rt_kprintf("usb-hid  send ok!!!");

return RT_EOK;

}
```