基于platform驱动模型完成LED驱动的编写

驱动程序

#include <linux/init.h>
#include <linux/module.h>
#include<linux/platform_device.h>
#include<linux/mod_devicetable.h>
#include<linux/of.h>
#include<linux/of_gpio.h>
#include<linux/gpio.h>
#include <linux/timer.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/device.h>
#include "head.h"

int major;   //字符设备驱动注册主设备号
struct class *cls;    //向上提交目录
struct device *dev;   //向上提交设备节点
struct gpio_desc* gpiono[3];

//封装操作方法
int mycdev_open(struct inode *inode, struct file *file)
{
	printk("%s:%s:%d\n", __FILE__,__func__,__LINE__);
	return 0;
}
long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	int which;
	int ret = copy_from_user(&which, (void*)arg,4); 
	if(ret)
	{
		printk("copy_from_user failed\n");
		return -EIO;
	}
	switch(cmd)
	{
		case LED_ON:
			switch(which)
			{
				case 1:
					gpiod_set_value(gpiono[0],1);
					break;
				case 2:
					gpiod_set_value(gpiono[1], 1);
					break;
				case 3:
					gpiod_set_value(gpiono[2], 1);
					break;
			}
			break;
		case LED_OFF:
			switch(which)
			{
				case 1:
					gpiod_set_value(gpiono[0],0);
					break;
				case 2:
					gpiod_set_value(gpiono[1], 0);
					break;
				case 3:
					gpiod_set_value(gpiono[2], 0);
					break;
			} 
			break;
	}

	printk("%s:%s:%d\n", __FILE__,__func__,__LINE__);
	return 0;
}
int mycdev_close(struct inode *inode, struct file *file)
{
	printk("%s:%s:%d\n", __FILE__,__func__,__LINE__);
	return 0;
}
//定义操作方法结构体变量
struct file_operations fops = {
	.open = mycdev_open,
	.unlocked_ioctl = mycdev_ioctl,
	.release = mycdev_close,
};

int pdrv_probe(struct platform_device *pdev)//当驱动和设备匹配成功之后执行
{
	//字符设备驱动注册
	major = register_chrdev(0, "mycdev",&fops);
	if(major < 0)
	{
		printk("字符设备驱动注册失败\n");
		return major;
	}
 
	/****************************udev创建设备节点的原************************/
	//向上提交目录
	cls = class_create(THIS_MODULE, "mycdev");
	if(IS_ERR(cls))
	{
		printk("向上提交目录失败\n");
		return -PTR_ERR(cls); 
	}
	//向上提交设备节点信息
	int i;
	for(i=0; i<3; i++)
	{
		dev = device_create(cls, NULL,MKDEV(major,i),NULL, "myled%d",i );
		if(IS_ERR(dev))
        {
            printk("向上提交设备节点失败\n");
            return -PTR_ERR(dev);
        }
	}
	printk("向上提交设备节点成功\n");


	//解析LED设备树节点获取三个节点的gpio信息
	for(i=0; i<3; i++)
	{
		gpiono[i]=gpiod_get_from_of_node(pdev->dev.of_node,"led-gpios", i, GPIOD_OUT_HIGH, NULL);
		if(IS_ERR(gpiono[i]))
		{
			printk("解析GPIO信息失败\n");
			return -PTR_ERR(gpiono[i]);
		}
		printk("解析GPIO信息成功\n");
	}
	return 0;
}

int pdrv_remove(struct platform_device *pdev)
{
	int i;
	for(i=0; i<3; i++)
	{
	gpiod_set_value(gpiono[i], 0);
	
	//释放gpio编号
	gpiod_put(gpiono[i]);
	//销毁设备节点信息
	device_destroy(cls, MKDEV(major, i));
	}
	
	//销毁目录
	class_destroy(cls);
	//注销字符设备驱动
	unregister_chrdev(major, "mycdev");
	return 0;
}
//构建设备树匹配表
struct of_device_id oftable[] = {
	{.compatible="hqyj,myplatform",},
	{.compatible="hqyj,myplatform1",},
	{},   //防止数组越界
};
//１分配驱动信息对象
struct platform_driver pdrv= {
	.probe=pdrv_probe,
	.remove=pdrv_remove,
	.driver={
		.name="bbbbb",   //驱动名
		.of_match_table=oftable,
	},
};

//驱动端一键注册宏
module_platform_driver(pdrv);
MODULE_LICENSE("GPL");

应用程序

#include<stdlib.h>
#include<stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include<unistd.h>
#include<string.h>
#include "head.h"

int main(int argc, char const *argv[])
{
    int fd = open("/dev/myled0", O_RDWR);
    if(fd < 0)
    {
        printf("打开设备文件失败\n");
        exit(-1);
    }
    while(1)
    {
        int a;
        printf("请输入1(开灯）０(关灯)>>");
        scanf("%d", &a);
        int b;
        printf("请输入 1(LED1) 2(LED2) 3(LED3)>>");
        scanf("%d", &b);
    
        switch(a)
        {
            case 1:
                ioctl(fd, LED_ON,&b);
                break;
            case 0:
                ioctl(fd, LED_OFF,&b);
                break; 
        }
    }
    close(fd);
    return 0;
}

head.h

#ifndef __HEAD_H__
#define __HEAD_H__
#define LED_ON _IOW('l', 1, int)
#define LED_OFF _IOW('l',0, int)
#endif