Linux系统下内核定时器的用法

 总的来说，timer的用法还是很简单的。主要需要定义一个timer_list变量timer、先初始化timer
　
　　init_timer（&timer）；
　
　　then 对timer的相关参数赋值：
　
　　timer.function = fun；
　
　　timer.expires = jiffies + TIMER_DELAY；
　
　　add_timer（&timer）；
　
　　在定时器时间到的时候，会执行fun，如果继续定时，可以通过
　
　　在fun中执行
　
　　mod_timer（&timer， jiffies + TIMER_DELAY）；
　
　　在不需要的时候通过调用
　
　　del_timer（&timer）；
　
　　删除定时器。
　
　　简单吧。这样一个简单的定时器就完成了。
　
　　呵呵。
　
　　附程序：
　
　　

#include <linux/module.h> #include <linux/types.h> #include <linux/fs.h> #include <linux/errno.h> #include <linux/mm.h> #include <linux/sched.h> #include <linux/init.h> #include <linux/cdev.h> #include <asm/io.h> #include <asm/system.h> #include <asm/uaccess.h> #include <linux/timer.h> #include <asm/atomic.h> #define SECOND_MAJOR 0 static int second_major = SECOND_MAJOR; struct second_dev { struct cdev cdev; atomic_t counter; struct timer_list s_timer; }; struct second_dev *second_devp; static void second_timer_handle(unsigned long arg) { mod_timer(&second_devp->s_timer, jiffies + HZ); atomic_inc(&second_devp->counter); printk(KERN_ERR "current jiffies is %ld/n",jiffies); } int second_open(struct inode *inode, struct file *filp) { init_timer(&second_devp->s_timer); second_devp->s_timer.function = &second_timer_handle; second_devp->s_timer.expires = jiffies + HZ; add_timer(&second_devp->s_timer); atomic_set(&second_devp->counter, 0); return 0; } int second_release(struct inode *inode, struct file *filp) { del_timer(&second_devp->s_timer); return 0; } static ssize_t second_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) { int counter; counter = atomic_read(&second_devp->counter); if (put_user(counter, (int *)buf)) { return -EFAULT; }else { return sizeof(unsigned int); } } static const struct file_operations second_fops = { .owner = THIS_MODULE, .open = second_open, .release = second_release, .read = second_read, }; static void second_setup_cdev(struct second_dev *dev, int index) { int err, devno = MKDEV(second_major, index); cdev_init(&dev->cdev, &second_fops); dev->cdev.owner = THIS_MODULE; dev->cdev.ops = &second_fops; err = cdev_add(&dev->cdev, devno, 1); if (err) { printk(KERN_NOTICE "Error %d add second%d", err, index); } } int second_init(void) { int ret; dev_t devno = MKDEV(second_major, 0); if (second_major) { ret = register_chrdev_region(devno, 1, "second"); }else { ret = alloc_chrdev_region(&devno, 0, 1, "second"); second_major = MAJOR(devno); } if (ret < 0) { return ret; } second_devp = kmalloc(sizeof(struct second_dev), GFP_KERNEL); if (!second_devp) { ret = -ENOMEM; goto fail_malloc; } memset(second_devp, 0, sizeof(struct second_dev)); second_setup_cdev(second_devp, 0); return 0; fail_malloc: unregister_chrdev_region(devno, 1); } void second_exit(void) { cdev_del(&second_devp->cdev); kfree(second_devp); unregister_chrdev_region(MKDEV(second_major, 0), 1); } MODULE_AUTHOR("Song Baohua"); MODULE_LICENSE("Dual BSD/GPL"); module_param(second_major, int, S_IRUGO); module_init(second_init); module_exit(second_exit); 附上用户端的测试程序： #include <stdio.h> #include <unistd.h> #include <fcntl.h> int main(void) { int fd, i; int data; fd = open("/dev/second",O_RDONLY); if (fd < 0) { printf("open /dev/second error/n"); } for(i = 0; i < 20; i++) { read(fd, &data, sizeof(data)); printf("read /dev/second is %d/n",data); sleep(1); } close(fd); }