驱动代码：
#include <linux/init.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/gpio.h>
#include<linux/fs.h>
#include<linux/io.h>
#include <linux/uaccess.h>
#include <linux/timer.h>
#include <linux/device.h>
#include <linux/cdev.h>
#include <linux/slab.h>
#include"head.h"
struct device_node *dnode;
struct gpio_desc *gpiono;
struct gpio_desc *gpiono1;
struct gpio_desc *gpiono2;
struct timer_list mytimer;
unsigned int major=0;
unsigned int minor=0;
struct cdev *mychdev;
struct class *cls;
struct device *dev;
dev_t devno;
int mycdev_open(struct inode *inode, struct file *file)
{
int min=MINOR(inode->i_rdev);//获取打开的的文件的次设备号
file->private_data= (void *)min;
printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
return 0;
}
long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
int min=(int)file->private_data;//获取到文件的次设备号
switch(min)
{
case 0: //控制LED1
switch(cmd)
{
case LED_ON: //开灯
gpiod_set_value(gpiono,1);
break;
case LED_OFF: //关灯
gpiod_set_value(gpiono,0);
break;
}
break;
case 1: //控制LED2
switch(cmd)
{
case LED_ON: //开灯
gpiod_set_value(gpiono1,1);
break;
case LED_OFF: //关灯
gpiod_set_value(gpiono1,0);
break;
}
break;
case 2: //控制LED3
switch(cmd)
{
case LED_ON: //开灯
gpiod_set_value(gpiono2,1);
break;
case LED_OFF: //关灯
gpiod_set_value(gpiono2,0);
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并赋值
struct file_operations fops = {
.open = mycdev_open,
.unlocked_ioctl = mycdev_ioctl,
.release = mycdev_close,
};
int k=0;
void mytimer_function(struct timer_list *timer)
{
k++;
if(k%5==0)
{
printk("hello world");
}
mod_timer(timer,jiffies+HZ);
}
//入口函数
static int __init mydev_init(void)
{
dnode=of_find_node_by_path("/myled");
if(dnode==NULL)
{
printk("解析设备树节点失败\n");
return -1;
}
//获取LED1 GPIO编号
gpiono=gpiod_get_from_of_node(dnode,"led-gpios",0,GPIOD_OUT_LOW,NULL);
gpiono1=gpiod_get_from_of_node(dnode,"led-gpios",1,GPIOD_OUT_LOW,NULL);
gpiono2=gpiod_get_from_of_node(dnode,"led-gpios",2,GPIOD_OUT_LOW,NULL);
//初始化定时器对象
timer_setup(&mytimer,mytimer_function,0);
mytimer.expires=jiffies+HZ;
//注册定时器
add_timer(&mytimer);
int ret;
//1.申请一个对象空间cdev_alloc
mychdev=cdev_alloc();
if(mychdev == NULL)
{
printk("申请字符设备驱动对象失败\n");
ret = -EFAULT;
goto out1;
}
printk("申请字符设备驱动对象成功\n");
//2.初始化对象cdev_init
cdev_init(mychdev,&fops);
//3.申请设备号 register_chrdev_region()/alloc_chrdev_region()
if(major == 0)
{
ret = alloc_chrdev_region(&devno,minor,3,"burger");
if(ret)
{
printk("动态申请设备号失败\n");
goto out2;
}
major=MAJOR(devno);
minor=MINOR(devno);
}
else
{
ret = register_chrdev_region(MKDEV(major,minor),3,"burger");
if(ret)
{
printk("静态申请设备号失败\n");
goto out2;
}
}
printk("申请设备号成功\n");
//4.注册驱动对象 cdev_add
ret = cdev_add(mychdev,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 class_create
cls=class_create(THIS_MODULE,"burger");
if(IS_ERR(cls))
{
printk("向上提交目录失败\n");
goto out4;
}
printk("向上提交目录成功\n");
//6.向上提交设备节点信息 device_create
int i; //向上提交三次设备节点信息
for(i=0;i<3;i++)
{
dev=device_create(cls,NULL,MKDEV(major,i),NULL,"burger%d",i);
if(IS_ERR(dev))
{
printk("向上提交节点失败\n");
goto out5;
}
}
printk("向上提交节点成功\n");
return 0;
out5:
for(--i;i>=0;i--)
{
device_destroy(cls,MKDEV(major,i));
}
class_destroy(cls);
out4:
cdev_del(mychdev);
out3:
unregister_chrdev_region(MKDEV(major,minor),3);
out2:
kfree(mychdev);
out1:
return ret;
}
//出口函数
static void __exit mydev_exit(void)
{
//灭灯
gpiod_set_value(gpiono,0);
gpiod_set_value(gpiono1,0);
gpiod_set_value(gpiono2,0);
//注销定时器
del_timer(&mytimer);
//释放GPIO信号
gpiod_put(gpiono);
gpiod_put(gpiono1);
gpiod_put(gpiono2);
//注销字符设备驱动
int i;
for(i=0;i<3;i++)
{
device_destroy(cls,MKDEV(major,i));
}
class_destroy(cls);
cdev_del(mychdev);
unregister_chrdev_region(MKDEV(major,minor),3);
kfree(mychdev);
}
//声明入口函数
module_init(mydev_init);
//声明出口函数
module_exit(mydev_exit);
MODULE_LICENSE("GPL");
应用程序代码：
#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 a,b,fd;
while(1)
{
fd=-1;
//从终端读取
printf("请输入要实现的功能 ");
printf("1(关灯) 0(开灯)\n");
printf("请输入>");
scanf("%d",&a);
printf("请选择要控制的灯：1（LED1）2(LED2) 3(LED3)\n");
printf("请输入>");
scanf("%d",&b);
switch(b)
{
case 1:
fd=open("/dev/burger0",O_RDWR);
if(a == 0)
{
ioctl(fd,LED_ON,&b);
break;
}
else
{
ioctl(fd,LED_OFF,&b);
break;
}
case 2:
fd=open("/dev/burger1",O_RDWR);
if(a == 0)
{
ioctl(fd,LED_ON,&b);
break;
}
else
{
ioctl(fd,LED_OFF,&b);
break;
}
case 3:
fd=open("/dev/burger2",O_RDWR);
if(a == 0)
{
ioctl(fd,LED_ON,&b);
break;
}
else
{
ioctl(fd,LED_OFF,&b);
break;
}
}
close(fd);
}
close(fd);
return 0;
}头文件：
#ifndef __HEAD_H__
#define __HEAD_H__
// 构建开灯关灯的功能码
#define LED_ON _IOW('l', 1,int)
#define LED_OFF _IOW('l', 0,int)
#endif 实验结果：
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