(linux自学笔记)linux内核定时器的使用

原文地址：

http://www.cnblogs.com/hebaichuanyeah/

很显然linux的内核定时器基于时钟节拍（和ucos一样）。ucos的时钟节拍可由void OS_CPU_SysTickInit (INT32U cnts)函数设置。在linux中，时钟节拍在param.h中定义。

timer驱动程序

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/poll.h>
#include <linux/irq.h>
#include <asm/irq.h>
#include <linux/interrupt.h>
#include <asm/uaccess.h>
#include <mach/regs-gpio.h>
#include <mach/hardware.h>
#include <linux/platform_device.h>
#include <linux/cdev.h>
#include <linux/miscdevice.h>
#include <linux/sched.h>
#include <linux/gpio.h>
#include <mach/gpio-bank-n.h>

#define DEVICE_NAME     "timer_device"
#define DEVICE_MAJOR    240

struct timer_list time_char_device;

void timer_handle(void)
{
    //改变定时器值
    mod_timer(&time_char_device,jiffies+HZ);
    printk("<0>timer handle
");
}

static int s3c6410_timer_open(struct inode *inode, struct file *file)
{
    //初始化
    init_timer(&time_char_device);
    //中断处理函数
    time_char_device.function = &timer_handle;
    //定时器值
    time_char_device.expires = jiffies+HZ;
    //加入定时器
    add_timer(&time_char_device);

    return 0;
}


static int s3c6410_timer_close(struct inode *inode, struct file *file)
{
    //删除定时器
    del_timer(&time_char_device);
    return 0;
}



static struct file_operations timer_device_fops =
{
    .owner      =   THIS_MODULE,
    .open       =   s3c6410_timer_open,
    .release    =   s3c6410_timer_close,

};



static int __init timer_device_init(void)
{
    int ret;
    printk ("<0>timer init
");
    //注册字符设备
    ret = register_chrdev(DEVICE_MAJOR,DEVICE_NAME,&timer_device_fops);
    if (ret <0)
    {
        printk ("<0>register %s char dev error
","timer");
        return -1;
    }
    printk ("<0>success
");
    return 0;
}

static void __exit timer_device_exit(void)
{
    //注销设备
    unregister_chrdev(DEVICE_MAJOR,DEVICE_NAME);
    printk ("<0>module exit
");
}

module_init(timer_device_init);
module_exit(timer_device_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("hebaichuan");

测试程序

#include <stdio.h>  
#include <stdlib.h>  
#include <unistd.h>  
#include <sys/ioctl.h>  
  
#define key_exit 5

int main(int argc, char **argv)  
{  
    int fd;  
        
    fd = open("/dev/timer_device",0);  
    if(fd<0) 
    {  
        printf("open devie error
");  
        return -1;  
    }  
  
    sleep(10);
    close(fd);  
    return 0;  
}  

程序运行结果