应用层.c

#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <sys/select.h>
#include <sys/time.h>
int main(int argc, char const *argv[])
{int fd1, fd2;char buf[128] = {0};// 打开文件fd1 = open("/dev/mycdev", O_RDWR);if (fd1 < 0){printf("打开设备文件失败\n");exit(-1);}fd2 = open("/dev/input/mouse0", O_RDWR);if (fd2 < 0){printf("打开鼠标设备文件失败\n");exit(-1);}// 创建读事件集合fd_set readfds;while (1){// 清空集合FD_ZERO(&readfds);// 添加文件描述符到事件集合FD_SET(fd1, &readfds);FD_SET(fd2, &readfds);// 阻塞等待事件发生int ret = select(fd2 + 1, &readfds, NULL, NULL, NULL);if (ret < 0){printf("select调用失败\n");return ret;}// 判断要监听的事件是否发生if (FD_ISSET(fd1, &readfds)){memset(buf, 0, sizeof(buf));read(fd1, buf, sizeof(buf));printf("自定义设备事件发生buf:%s\n", buf);}if (FD_ISSET(fd2, &readfds)){memset(buf, 0, sizeof(buf));read(fd2, buf, sizeof(buf));printf("鼠标设备事件发生buf:%s\n", buf);}}close(fd1);close(fd2);return 0;
}

 模拟自定义事件硬件数据到达的进程.c

#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[])
{int a,b;char buf[128]="hello world";int fd=open("/dev/mycdev",O_RDWR);if(fd<0){printf("打开设备文件失败\n");exit(-1);}write(fd,buf,sizeof(buf));close(fd);return 0;
}

驱动.c

#include <linux/init.h>
#include <linux/module.h>
#include<linux/fs.h>
#include<linux/io.h>
#include<linux/device.h>
#include<linux/uaccess.h>
#include<linux/poll.h>struct class *cls;
struct device *dev;unsigned int major;//定义一个变量保存主设备号
char kbuf[128]={0};//定义等待队列头
wait_queue_head_t wq_head;
int condition=0;//数据是否准备好的标志变量//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;
}
ssize_t mycdev_read(struct file *file, char  *ubuf, size_t size, loff_t *lof)
{printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);if(size>sizeof(kbuf))//用户的需求内核满足不了{size=sizeof(kbuf);}long ret;ret=copy_to_user(ubuf,kbuf,size);if(ret){printk("copy_to_user filed\n");return -EIO;}condition=0;//表示下一次数据没有准备好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__);if(size>sizeof(kbuf))//用户的需求内核满足不了{size=sizeof(kbuf);}long ret;ret=copy_from_user(kbuf,ubuf,size);//表示模拟硬件数据就绪if(ret){printk("copy_from_user filed\n");return -EIO;}condition=1;wake_up_interruptible(&wq_head);//唤醒休眠的进程return 0;
}//封装poll方法
__poll_t mycdev_poll(struct file *file, struct poll_table_struct *wait)
{__poll_t mask=0;//1.向上提交等待队列头poll_wait(file,&wq_head,wait);//2.根据事件是否发生给一个合适的返回值if(condition){mask=POLLIN;}return mask;
}
int mycdev_close(struct inode *inode, struct file *file)
{printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);return 0;
}
//定义一个操作方法结构体变量并且初始化
struct file_operations fops={.open=mycdev_open,.release=mycdev_close,.read=mycdev_read,.poll=mycdev_poll,.write=mycdev_write,
};
static int __init mycdev_init(void)
{//初始化等待队列头init_waitqueue_head(&wq_head);//注册字符设备驱动major=register_chrdev(0,"mychrdev",&fops);if(major<0){printk("注册字符设备驱动失败\n");return major;}printk("注册字符设备驱动成功major=%d\n",major);// 向上提交目录cls = class_create(THIS_MODULE, "myled");if (IS_ERR(cls)){printk("向上提交目录失败\n");return -PTR_ERR(cls);}printk("向上提交目录信息成功\n");// 向上提交设备节点信息dev = device_create(cls, NULL, MKDEV(major, 0), NULL, "mycdev");if (IS_ERR(dev)){printk("向上提交设备节点信息失败\n");return -PTR_ERR(dev);}printk("向上提交设备节点成功\n");return 0;
}
static void __exit mycdev_exit(void)
{// 销毁节点信息device_destroy(cls, MKDEV(major, 0));// 销毁目录信息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");

***********epoll***************

#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>
#include"myled.h"int main(int argc, char const *argv[])
{int fd1,fd2,epfd;struct epoll_event event;struct epoll_event events[10];//存放就绪事件描述符的数组char buf[128]={0};
//创建epoll句柄
epfd=epoll_create(1);
if(epfd<0)
{printf("epoll_create filed\n");exit(-1);
}
//打开设备文件fd1=open("/dev/input/mouse0",O_RDWR);if(fd1<0){printf("打开鼠标设备文件失败\n");exit(-1);}fd2=open("/dev/my_led0",O_RDWR);if(fd2<0){printf("打开鼠标设备文件失败\n");exit(-1);}//添加准备就绪事件进入epoll;event.events=EPOLLIN;//读事件event.data.fd=fd1;if(epoll_ctl(epfd,EPOLL_CTL_ADD,fd1,&event)<0){printf("epoll_ctl add filed\n");}event.events=EPOLLIN;//读事件event.data.fd=fd2;if(epoll_ctl(epfd,EPOLL_CTL_ADD,fd2,&event)<0){printf("epoll_ctl add filed\n");}//监听事件是否发生while(1){//如果成功，ret接收返回的事件个数，把就绪的事件放在events数组中int ret=epoll_wait(epfd,events,10,-1);if(ret<0){printf("epoll_wait filed\n");exit(-1);}int i;//循环遍历数组，做事件的处理for(i=0;i<ret;i++){if(events[i].events&EPOLLIN){read(events[i].data.fd,buf,sizeof(buf));printf("buf:%s\n",buf);}}}close(fd1);close(fd2);return 0;
}