linux内核定时器的用法

今天参考linux驱动开发详解，照抄了一份second的程序，用到了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); }

原文地址 http://blogold.chinaunix.net/u1/49088/showart_494267.html