linux内核定时器的用法(含有例子)

gaofei8530

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
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#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 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
#include
#include
int main(void)
{
    int fd, i;
    int data;
    fd = open("/dev/second",O_RDONLY);
    if (fd
转自：
http://blog.chinaunix.net/u1/49088/showart_494267.html


本文来自ChinaUnix博客，如果查看原文请点：http://blog.chinaunix.net/u3/101356/showart_2052982.html