timer_list变量timer

 

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); }