linux 内核定时器编程

1.linux内核定时器基本结构和函数

1）struct timer_list 一个struct timer_list对应了一个定时器。

#include <linux/timer.h>

以下列出常用的接口：

struct timer_list

{

/*....*/

unsigned long expires;//定时器服务函数开始执行时间

void (*function)(unsigned long);//定义一个指向定时器服务函数的指针function，服务函数有一个 unsigned long的参数，并且返回void

unsigned long data；//定时时间到时，data参数会传入服务函数

}

void init_timer(struct timer_list* timer)//初始化一个定时器

-----------使用定时器的步骤--------------

struct timer_list my_timer_list;//定义一个定时器，可以把它放在你的设备结构中

init_timer(&my_timer_list);//初始化一个定时器

my_timer_list.expire=jiffies+HZ;//定时器1s后运行服务程序

my_timer_list.function=timer_function;//定时器服务函数

add_timer(&my_timer_list);//添加定时器

void timer_function(unsigned long)//写定时器服务函数

del_timer(&my_timer_list);//当定时器不再需要时删除定时器

del_timer_sync(&my_timer_list);//基本和del_timer一样，比较适合在多核处理器使用，一般推荐使用del_timer_sync

-------------------------------------------------

2.以下是一个定时1s的驱动程序，直接上代码

#include <linux/miscdevice.h>
#include <linux/delay.h>
#include <asm/irq.h>
//#include <mach/regs-gpio.h>
//#include <mach/hardware.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/ioctl.h>
#include <linux/cdev.h>
#include <linux/string.h>
#include <linux/list.h>
#include <linux/pci.h>
#include <asm/uaccess.h>
#include <asm/atomic.h>
#include <asm/unistd.h>
#include <asm/io.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#define TIMER_MAJOR 300
#define TIMER_MINOR 0
dev_t timer_dev_t;//设备号
dev_t timer_dev_major=TIMER_MAJOR;
dev_t timer_dev_minor=TIMER_MINOR;
struct TIMER_DEV
{
  struct cdev cdev;
  atomic_t count;
  struct timer_list timer_list;

};
struct TIMER_DEV* timer_dev;
//---------timer interrupt function----------------
static void timer_function(unsigned long data)
{
mod_timer(&(timer_dev->timer_list),jiffies+HZ);//重新设置时间
printk("current jiffies is %ld,count=%d\n",jiffies,timer_dev->count);
//(timer_dev->count)++;
atomic_inc(&(timer_dev->count));
}
//--------timer release function--------------------
static int timer_release(struct inode* inode, struct file* filp)
{
del_timer_sync(&(timer_dev->timer_list));
return 0;
}

//----------------file open function-----------------
static int timer_open(struct inode* inode,struct file* filp)
{
init_timer(&(timer_dev->timer_list));//初始化定时器
timer_dev->timer_list.function=timer_function;//设置定时器处理函数
timer_dev->timer_list.expires=jiffies+HZ;//处理函数1s后运行
add_timer(&timer_dev->timer_list);//添加定时器
atomic_set(&(timer_dev->count),0);
return 0;
}
//--------------------------------------

//----------------timer_read function---------------
static int timer_read(struct file* filp,char __user *buf,size_t count,loff_t* f_pos)
{

 unsigned int counter=atomic_read(&(timer_dev->count));
if(copy_to_user(buf,(unsigned int*)&counter,sizeof(unsigned int)))
  {
   printk("copy to user error\n");
   goto out;
  }
return (sizeof(unsigned int));
out:
return (-EFAULT);

}

struct file_operations timer_ops={
.owner=THIS_MODULE,
.open=timer_open,
.read=timer_read,
.release=timer_release,
};
static int __init timer_init(void)
{
 int ret;

 if(TIMER_MAJOR)//主设备号大于0，静态申请设备号
	{
	timer_dev_t=MKDEV(TIMER_MAJOR,TIMER_MINOR);
	ret=register_chrdev_region(TIMER_MAJOR,1,"timer_dev");//first,count,name
	}
 else
	{
	ret=alloc_chrdev_region(&timer_dev_t,0,1,"time_dev");
	timer_dev_major=MAJOR(timer_dev_t);
	}
 if(ret<0)
	{
	printk("can't get major %d\n",timer_dev_major);
	return ret;
	}
//-----------------------------------------------------------
 timer_dev=kmalloc(sizeof(struct TIMER_DEV),GFP_KERNEL); 
	memset(timer_dev,0,sizeof(struct TIMER_DEV));
 cdev_init(&(timer_dev->cdev),&timer_ops);
 cdev_add(&(timer_dev->cdev),timer_dev_t,1);
 printk("init timer_dev success\n");
return 0;


}
static void __exit timer_exit(void)
{
kfree(timer_dev);
cdev_del(&(timer_dev->cdev));
unregister_chrdev_region(MKDEV(TIMER_MAJOR,0),1);
}
module_init(timer_init);
module_exit(timer_exit);

测试程序

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
int main()
{
int fd;
int i;
int counter=0;
int old_counter=0;
fd=open("/dev/timer_dev",O_RDWR);
if(fd<0)
{
printf("open file error\n");
exit(1);
}
for(i=0;i<30;)//运行30s
  {
  read(fd,&counter,sizeof(int));
 if(counter!=old_counter)
    {
     printf("second=%d\n",counter);
     old_counter=counter;
    i++;
    }

  }
close(fd);
exit (0);

}

测试结果添加模块后使用dmesg查看内核信息

[ 1239.176994] current jiffies is 235468,count=123
[ 1240.174459] current jiffies is 235718,count=124
[ 1241.171920] current jiffies is 235968,count=125
[ 1242.169383] current jiffies is 236218,count=126

测试程序的结果

second=1
second=2
second=3
second=4
second=5
second=6
second=7
second=8
second=9
second=10
second=11

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linux 内核定时器编程

1.linux内核定时器基本结构和函数

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