驱动程序

#include <linux/init.h>
#include <linux/module.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 <linux/wait.h>
#include <linux/uaccess.h>
#include <linux/poll.h>
#include <linux/cdev.h>
#include <linux/slab.h>
struct device_node *dnode;
struct gpio_desc *gpiono;
struct gpio_desc *gpiono2;
struct gpio_desc *gpiono3;
struct timer_list mytimer;
struct cdev *cdev;
unsigned int major=0;
unsigned int minor=0;
dev_t devno;
struct class *cls;
struct device *dev;
char kbuf[128] = {0};void mytimer_function(struct timer_list *timer){printk("hello,world\n");//再次启用定时器mod_timer(timer,jiffies+HZ*5);}int mycdev_open(struct inode *inode, struct file *file)
{printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);return 0;
}
ssize_t mycdev_read(struct file *file, char *ubuf, size_t size, loff_t *lof)
{printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);return 0;
}
ssize_t mycdev_write(struct file *file, const char *ubuf, size_t size, loff_t *lof)
{printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);int ret=copy_from_user(kbuf,ubuf,size);if(kbuf[0]=='1'){gpiod_set_value(gpiono,!gpiod_get_value(gpiono));}else if(kbuf[0]=='2'){gpiod_set_value(gpiono2,!gpiod_get_value(gpiono2));}else if(kbuf[0]=='3'){gpiod_set_value(gpiono3,!gpiod_get_value(gpiono3));}if(ret){printk("error\n");return -EIO;}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对象，保存封装的操作方法
struct file_operations fops = {.open=mycdev_open,.read=mycdev_read,.write=mycdev_write,.release=mycdev_close,
};
static int __init mycdev_init(void)
{//1.申请一个对象空间cdev_allocint ret;cdev= cdev_alloc();if(cdev==NULL){printk("申请字符设备驱动对象失败\n");ret=-EFAULT;goto out1;}printk("字符设备驱动对象申请成功\n");//2.初始化对象cdev_initcdev_init(cdev,&fops);//3.申请设备号  register_chrdev_region()/alloc_chrdev_region()if(major==0)//动态申请{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);//根据设备号获取主设备号minor=MINOR(devno);//根据设备号获取次设备号}else{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("设备号申请成功\n");//4.注册驱动对象  cdev_addret=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  class_createcls=class_create(THIS_MODULE,"mychrdev");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_createint i;for(i=0;i<3;i++){dev=device_create(cls,NULL,MKDEV(major,i),NULL,"mycdev%d",i);if(IS_ERR(dev)){printk("向上提交设备节点失败\n");goto out5;}}printk("向上提交设备节点信息成功\n");//解析设备树节点信息dnode=of_find_node_by_path("/myled");if(dnode==NULL){printk("解析设备树节点失败\n");return -ENXIO;}//获取LED1 GPIO编号//获取led1 gpio编号gpiono=gpiod_get_from_of_node(dnode,"led1-gpio",0,GPIOD_OUT_LOW,NULL);if(IS_ERR(gpiono)){printk("申请gpio信息失败\n");return -PTR_ERR(gpiono);}gpiono2=gpiod_get_from_of_node(dnode,"led2-gpio",0,GPIOD_OUT_LOW,NULL);if(IS_ERR(gpiono2)){printk("申请gpio信息失败\n");return -PTR_ERR(gpiono2);}gpiono3=gpiod_get_from_of_node(dnode,"led3-gpio",0,GPIOD_OUT_LOW,NULL);if(IS_ERR(gpiono3)){printk("申请gpio信息失败\n");return -PTR_ERR(gpiono3);}//初始化定时器对象timer_setup(&mytimer,mytimer_function,0);mytimer.expires=jiffies+HZ*5;//定时1s;//注册定时器add_timer(&mytimer);return 0;out5:
//将提交成功的节点信息释放for(--i;i>=0;i--){device_destroy(cls,MKDEV(major,i));}//销毁目录class_destroy(cls);
out4:cdev_del(cdev);
out3:unregister_chrdev_region(MKDEV(major,minor),3);
out2:kfree(cdev);
out1:return ret;
}
static void __exit mycdev_exit(void)
{del_timer(&mytimer);int i;for(i=0;i<3;i++){device_destroy(cls,MKDEV(major,i));}//2.销毁目录class_destroy(cls);//3.注销字符设备驱动对象cdev_del(cdev);//4.释放设备号unregister_chrdev_region(MKDEV(major,minor),3);//5.释放申请到的字符设备驱动对象空间kfree(cdev);
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

应用程序

#include<stdlib.h>
#include<stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include<unistd.h>
#include<string.h>int main(int argc, char const *argv[])
{char buf[128]={0};int fd=open("/dev/mycdev0",O_RDWR);if(fd<0){printf("打开设备文件失败\n");exit(-1);}while(1){//从终端读取printf("请输入两个字符\n");printf("第一个字符:1(LED1) 2(LED2) 3(LED3)\n");fgets(buf,sizeof(buf),stdin);buf[strlen(buf)-1]='\0';//向设备文件中写write(fd,buf,sizeof(buf));}close(fd);return 0;
}

现象