RTThread自定义IO设备接口

RT-Thread 提供了一套 I/O 设备模型框架方便用户在自定义一些特殊IO设备，提供统一的IO设备创建、注册、接口定义、注销等设备管理实现设备驱动程序的封装，应用程序通过 I/O 设备层提供的标准接口访问底层设备，设备驱动程序的升级、更替不会对上层应用产生影响。

RT-Thread 自定义IO设备用到的功能函数，存放在rt-thread/src/device.c源码文件下，相关宏定义主要在rt-thread/src/rtdef.h源文件中。

一、 源码示例【1】，IO设备创建与注册

#include <rtthread.h>
#include <rtdef.h>

rt_err_t  init_test(rt_device_t dev)
{
    rt_kprintf("init_test run!
");
    return 0;
}
rt_err_t  open_test(rt_device_t dev, rt_uint16_t oflag)
{
    rt_kprintf("open_test run!
");
    return 0;
}

rt_err_t  close_test(rt_device_t dev)
{
    rt_kprintf("close_test run!
");
    return 0;
}

static int iodef_reg_sample(int argc, char *argv[])
{
	rt_device_t dev = rt_device_create(RT_Device_Class_Char,64);
	if(dev==RT_NULL)
	{
	    rt_kprintf("rt_device_create failed!
");
	    return RT_ERROR;
	}
	//I/O 设备的操作方法的映射，更多参考rt_device_t结构体定义
	dev->init = init_test;
	dev->open = open_test;
	dev ->close = close_test;
	rt_err_t ret = rt_device_register(dev,"devtest",RT_DEVICE_FLAG_RDWR);
	if(ret!=RT_EOK)
	{
	    rt_kprintf("rt_device_register failed!
");
	    return RT_ERROR;
	}
	return RT_EOK;
}

/* 导出到 msh 命令列表中 */
MSH_CMD_EXPORT(iodef_reg_sample, io define for user register test example);

二、源码示例【2】，已注册IO设备功能接口调用

#include <rtthread.h>
#include <rtdef.h>

static int iodef_use_sample(int argc, char *argv[])
{
    rt_device_t dev = rt_device_find("devtest");
    if(dev==RT_NULL)
    {
        rt_kprintf("rt_device_find failed!
");
        return RT_ERROR;
    }
    rt_device_init(dev);
    rt_device_open(dev, RT_DEVICE_FLAG_RDWR);
    rt_device_close(dev);
    return RT_EOK;
}

/* 导出到 msh 命令列表中 */
MSH_CMD_EXPORT(iodef_use_sample, io define for user and be used test example);

三、源码示例【3】，注销自定义IO设备

#include <rtthread.h>
#include <rtdef.h>

static int iodef_ureg_sample(int argc, char *argv[])
{
    rt_device_t dev = rt_device_find("devtest");
    if(dev==RT_NULL)
    {
        rt_kprintf("rt_device_find failed!
");
        return RT_ERROR;
    }
    rt_err_t ret = rt_device_unregister(dev);
    if(ret!=RT_EOK)
    {
        rt_kprintf("rt_device_unregister failed!
");
        return RT_ERROR;
    }
    return RT_EOK;
}

/* 导出到 msh 命令列表中 */
MSH_CMD_EXPORT(iodef_ureg_sample, io define for user unregister test example);

四、效果展示