基于GPIO子系统编写LED驱动，编写应用程序进行测试，设置定时器，5秒钟打印一次hello world

设备树添加的代码

 myled{
     led-gpios=<&gpioe 10 0>, <&gpiof 10 0>, <&gpioe 8 0>;   
 };

头文件

#ifndef __HEAD_H__
#define __HEAD_H__

#define LED_ON _IO('l', 1)
#define LED_OFF _IO('l', 0)

#endif

驱动代码

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include "head.h"

//定义变量，字符设备驱动对象
struct cdev *cdev;
//定义变量，主设备号、次设备号、设备号
unsigned int major = 0;
unsigned int minor = 0;
dev_t devno;
//定义变量，向上提交目录信息返回值
struct class *cls;
//定义变量，向上提交设备节点信息返回值
struct device *dev;
//定义变量，解析设备节点信息
struct device_node *dnode;
//定义变量，保存GOIO的对象信息的结构体指针
struct gpio_desc *gpiono[3];
//定义变量，分配一个定时器对象
struct timer_list mytimer;

int mycdev_open(struct inode *inode, struct file *file)
{
	int min = MINOR(inode->i_rdev);  //获取打开的文件的次设备号
	file->private_data = (void *)min;
	return 0;
}
long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	int which;
	which = (int)file->private_data;  //获取到文件的次设备号
	switch(which)
	{
		case 0:
			switch(cmd)
			{
				case LED_OFF:
					gpiod_set_value(gpiono[0], 0);
					break;
				case LED_ON:
					gpiod_set_value(gpiono[0], 1);
					break;
			}
			break;
		case 1:
			switch(cmd)
			{
				case LED_OFF:
					gpiod_set_value(gpiono[1], 0);
					break;
				case LED_ON:
					gpiod_set_value(gpiono[1], 1);
					break;
			}
			break;
		case 2:
			switch(cmd)
			{
				case LED_OFF:
					gpiod_set_value(gpiono[2], 0);
					break;
				case LED_ON:
					gpiod_set_value(gpiono[2], 1);
					break;
			}
			break;
	}
	return 0;
}
int mycdev_close(struct inode *inode, struct file *file)
{
	return 0;
}
//操作方法结构体
struct file_operations fop ={
	.open = mycdev_open,
	.unlocked_ioctl = mycdev_ioctl,
	.release = mycdev_close,
};

//声明注册驱动、创建设备文件的函数
int register_file(void);

//GPIO子系统---led灯
int	gpio_led(void);

//定时器处理函数
void timer_handel(struct timer_list *timer)
{
	printk("hello world\n");
	mod_timer(timer, jiffies+5*HZ);
}
//入口函数
static int __init mycdev_init(void)
{
	//调用注册驱动，创建设备文件
	register_file();
	
	//GPIO子系统---led灯
	gpio_led();
	
	//初始化定时器
	timer_setup(&mytimer, timer_handel, 0);
	mytimer.expires = jiffies+5*HZ;
	//注册定时器并启用
	add_timer(&mytimer);
	return 0;
}

//出口函数
static void __exit mycdev_exit(void)
{
	//销毁设备节点
	int i;
	for(i=0; i<3;i++)
	{
		device_destroy(cls, MKDEV(major, i));
	}
	//销毁目录信息
	class_destroy(cls);
	//分布注销驱动
	//1.注销字符设备驱动
	cdev_del(cdev);
	//2.释放设备号
	unregister_chrdev_region(MKDEV(major, minor), 3);
	//3.释放字符设备驱动对象空间
	kfree(cdev);

	//释放GPIO编号
	for(i=0; i<3; i++)
	{
		gpiod_put(gpiono[i]);
	}
	//关闭定时器
	del_timer(&mytimer);
}

//注册驱动，创建设备文件
int register_file(void)
{
	//1.申请字符设备驱动对象
	cdev = cdev_alloc();
	if(NULL == cdev)
	{
		printk("申请字符设备驱动对象失败\n");
		goto out1;
	}
	printk("申请字符设备驱动对象成功\n");
	//2.初始化字符设备驱动对象
	cdev_init(cdev, &fop);
	//3.申请设备号
	if(0 == major)
	{
		//动态申请字符设备
		int ret = alloc_chrdev_region(&devno, minor, 3, "mychrdev");
		if(ret)
		{
			printk("动态申请设备号失败\n");
			goto out2;
		}
		major = MAJOR(devno);
		minor = MINOR(devno);
		printk("动态申请设备号成功\n");
	}
	else
	{
		//静态指定设备号
		int ret = register_chrdev_region(MKDEV(major, minor), 3, "mychrdev");
		if(ret)
		{
			printk("静态指定设备号失败\n");
			goto out2;
		}
		printk("静态指定设备号成功\n");
	}
	//4.注册字符设备驱动对象
	int ret = cdev_add(cdev, MKDEV(major, minor), 3);
	if(ret)
	{
		printk("注册字符设备驱动对象失败\n");
		goto out3;
	}
	printk("注册字符设备驱动对象成功\n");
	//5.向上提交目录信息
	cls = class_create(THIS_MODULE, "mychrdev");
	if(IS_ERR(cls))
	{
		printk("向上提交目录信息失败\n");
		goto out4;
	}
	printk("向上提交目录信息成功\n");
	//6.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("向上提交设备节点信息失败\n");
			goto out5;
		}
	}
	printk("向上提交设备节点信息成功\n");
	return 0;
	out5:
		//销毁设备节点
		for(;i>0;i--)
		{
			device_destroy(cls, MKDEV(major, i));
		}
		//销毁目录
		class_destroy(cls);
	out4:
		//注销字符设备驱动
		cdev_del(cdev);
	out3:
		//释放设备号
		unregister_chrdev_region(MKDEV(major, minor), 3);
	out2:
		//释放字符设备驱动对象空间
		kfree(cdev);
	out1:
		return -1;
}

//GPIO子系统---led灯
int gpio_led(void)
{
	//1.解析设备树节点信息
	dnode = of_find_node_by_path("/myled");
	if(NULL == dnode)
	{
		printk("解析设备树节点信息失败\n");
		return dnode;
	}
	printk("解析设备树节点信息成功\n");
	//2.获取、申请GPIO编号和指定管脚输入输出方向
	int i;
	for(i=0; i<3; i++)
	{
		gpiono[i] = gpiod_get_from_of_node(dnode, "led-gpios", i, GPIOD_OUT_LOW, NULL);
		if(IS_ERR(gpiono[i]))
		{
			printk("申请GPIO编号失败\n");
			return -PTR_ERR(gpiono[i]);
		}
	}
	printk("申请GPIO编号成功\n");
	return 0;
}

module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

应用程序代码

#include 
#include 
#include 
#include 
#include 
#include 
#include "head.h"


int main(int argc, const char *argv[])
{
	int fd1, fd2, fd3;
	int led_choose, on_off_choose;
	while(1)
	{
		printf("请选择开启哪一盏灯(1 led1) (2 led2) (3 led3)：");
		scanf("%d", &led_choose);
		printf("请选择关灯or开灯(0 off) (1 on)：");
		scanf("%d", &on_off_choose);
		switch(led_choose)
		{
			case 1:
				fd1 = open("/dev/myled0", O_RDWR);
				switch(on_off_choose)
				{
					case 0:
						ioctl(fd1, LED_OFF);
						break;

					case 1:
						ioctl(fd1, LED_ON);
						break;
				}
				close(fd1);
				break;
			case 2:
				fd2 = open("/dev/myled1", O_RDWR);
				switch(on_off_choose)
				{
					case 0:
						ioctl(fd2, LED_OFF);
						break;

					case 1:
						ioctl(fd2, LED_ON);
						break;
				}
				close(fd2);
				break;
			case 3:
				fd3 = open("/dev/myled2", O_RDWR);
				switch(on_off_choose)
				{
					case 0:
						ioctl(fd3, LED_OFF);
						break;

					case 1:
						ioctl(fd3, LED_ON);
						break;
				}
				close(fd3);
				break;
		}
	}
	return 0;