驱动day8-编程知识

驱动day8

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

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/timer.h>struct device_node *dnode;
struct gpio_desc *gpiono1;
struct gpio_desc *gpiono2;
struct gpio_desc *gpiono3;
struct timer_list mytimer;struct class *cls;
struct device *dev;
int major;
char kbuf[128]={0};//定时器处理函数
void mytimer_funtion(struct timer_list *timer)
{printk("hello world");mod_timer(timer,jiffies+5*HZ);
}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__);int ret=copy_to_user(ubuf,kbuf,size);if(ret){printk("copy_to_user filed\n");return -EIO;}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(ret){printk("copy_from_user filed\n");return -EIO;}//设定该GPIO管脚的输出值if(kbuf[0]=='0'){gpiod_set_value(gpiono1,0);gpiod_set_value(gpiono2,0);gpiod_set_value(gpiono3,0);       }else if(kbuf[0]=='1'){gpiod_set_value(gpiono1,1);gpiod_set_value(gpiono2,1);gpiod_set_value(gpiono3,1); }return 0;
}int mycdev_close(struct inode *inode,struct file *file)
{printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);return 0;
}struct file_operations fops ={.open=mycdev_open,.read=mycdev_read,.write=mycdev_write,.release=mycdev_close,
};static int __init mycdev_init(void)
{// 字符设备驱动注册major = register_chrdev(0, "mychrdev", &fops);if (major < 0){printk("字符设备驱动注册失败\n");return major;}printk("字符设备驱动注册成功:major=%d\n", major);// 向上提交目录cls = class_create(THIS_MODULE, "mychrdev");if (IS_ERR(cls)){printk("向上提交目录失败\n");return -PTR_ERR(cls);}printk("向上提交目录成功\n");// 向上提交设备节点信息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, "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gpiono1=gpiod_get_from_of_node(dnode,"led1-gpio",0,GPIOD_OUT_LOW,NULL);if(IS_ERR(gpiono1)){printk("申请gpiono1信息失败\n");return -PTR_ERR(gpiono1);}gpiono2=gpiod_get_from_of_node(dnode,"led2-gpio",0,GPIOD_OUT_LOW,NULL);if(IS_ERR(gpiono2)){printk("申请gpiono3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gpiono3信息失败\n");return -PTR_ERR(gpiono3);}//初始化定时器对象timer_setup(&mytimer,mytimer_funtion,0);mytimer.expires=jiffies+HZ;//注册定时器add_timer(&mytimer);return 0;
}
static void __exit mycdev_exit(void)
{del_timer(&mytimer);gpiod_set_value(gpiono3,0);gpiod_put(gpiono3);gpiod_set_value(gpiono3,0);gpiod_put(gpiono3);gpiod_set_value(gpiono3,0);gpiod_put(gpiono3);// 销毁设备节点信息int i;for (i = 0; i < 3; i++){device_destroy(cls, MKDEV(major, i));}// 销毁目录class_destroy(cls);// 注销字符设备驱动unregister_chrdev(major, "mychrdev");}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

应用代码

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/wait.h>
#include <sys/ioctl.h>
#include <sys/select.h>
#include <sys/epoll.h>
/* According to earlier standards */
#include <sys/time.h>
int fd1,fd2,fd3;
char buf[128] ={0};
int main(int argc, char const *argv[])
{fd1 = open("/dev/myled0", O_RDWR);if (fd1 < 0){printf("打开设备文件失败\n");exit(-1);}while (1){printf("请输入0(关灯),1(开灯):"); fgets(buf,sizeof(buf),stdin);//write(fd2,buf,1);//write(fd3,buf,1);buf[strlen(buf)-1]='\0';write(fd1,buf,sizeof(buf));}close(fd1);return 0;
}

现象: