linux底层驱动之定时器

定时器
1>
/*second设备结构体*/
struct second_dev
{
 struct cdev cdev; /*cdev结构体*/
 atomic_t counter;/* 一共经历了多少秒？*/
 struct timer_list s_timer; /*设备要使用的定时器*/
};

2>
/*文件打开函数*/
int second_open(struct inode *inode, struct file *filp)
{
 /*初始化定时器*/
 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); /*添加（注册）定时器*/

 atomic_set(&second_devp->counter,0); //计数清0

 return 0;
}
3>
/*定时器处理函数*/
static void second_timer_handle(unsigned long arg)
{
 mod_timer(&second_devp->s_timer,jiffies + HZ );
 atomic_inc(&second_devp->counter);

 printk(KERN_NOTICE "current jiffies is %ld\n", jiffies);
}
4>
/*文件释放函数*/
int second_release(struct inode *inode, struct file *filp)
{
 del_timer(&second_devp->s_timer);

 return 0;
}