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
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
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#include <linux/miscdevice.h>
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#include <linux/delay.h>
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#include <asm/irq.h>
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//#include <mach/regs-gpio.h>
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//#include <mach/hardware.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/mm.h>
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#include <linux/fs.h>
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#include <linux/types.h>
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#include <linux/delay.h>
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#include <linux/moduleparam.h>
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#include <linux/slab.h>
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#include <linux/errno.h>
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#include <linux/ioctl.h>
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#include <linux/cdev.h>
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#include <linux/string.h>
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#include <linux/list.h>
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#include <linux/pci.h>
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#include <asm/uaccess.h>
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#include <asm/atomic.h>
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#include <asm/unistd.h>
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#include <asm/io.h>
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#include <asm/system.h>
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#include <asm/uaccess.h>
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#define TIMER_MAJOR 300
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#define TIMER_MINOR 0
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dev_t timer_dev_t;//设备号
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dev_t timer_dev_major=TIMER_MAJOR;
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dev_t timer_dev_minor=TIMER_MINOR;
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struct TIMER_DEV
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{
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struct cdev cdev;
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atomic_t count;
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struct timer_list timer_list;
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};
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struct TIMER_DEV* timer_dev;
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//---------timer interrupt function----------------
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static void timer_function(unsigned long data)
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{
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mod_timer(&(timer_dev->timer_list),jiffies+HZ);//重新设置时间
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printk("current jiffies is %ld,count=%d\n",jiffies,timer_dev->count);
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//(timer_dev->count)++;
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atomic_inc(&(timer_dev->count));
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}
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//--------timer release function--------------------
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static int timer_release(struct inode* inode, struct file* filp)
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{
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del_timer_sync(&(timer_dev->timer_list));
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return 0;
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}
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//----------------file open function-----------------
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static int timer_open(struct inode* inode,struct file* filp)
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{
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init_timer(&(timer_dev->timer_list));//初始化定时器
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timer_dev->timer_list.function=timer_function;//设置定时器处理函数
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timer_dev->timer_list.expires=jiffies+HZ;//处理函数1s后运行
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add_timer(&timer_dev->timer_list);//添加定时器
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atomic_set(&(timer_dev->count),0);
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return 0;
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}
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//--------------------------------------
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//----------------timer_read function---------------
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static int timer_read(struct file* filp,char __user *buf,size_t count,loff_t* f_pos)
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{
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unsigned int counter=atomic_read(&(timer_dev->count));
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if(copy_to_user(buf,(unsigned int*)&counter,sizeof(unsigned int)))
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{
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printk("copy to user error\n");
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goto out;
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}
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return (sizeof(unsigned int));
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out:
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return (-EFAULT);
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}
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struct file_operations timer_ops={
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.owner=THIS_MODULE,
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.open=timer_open,
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.read=timer_read,
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.release=timer_release,
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};
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static int __init timer_init(void)
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{
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int ret;
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if(TIMER_MAJOR)//主设备号大于0,静态申请设备号
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{
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timer_dev_t=MKDEV(TIMER_MAJOR,TIMER_MINOR);
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ret=register_chrdev_region(TIMER_MAJOR,1,"timer_dev");//first,count,name
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}
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else
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{
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ret=alloc_chrdev_region(&timer_dev_t,0,1,"time_dev");
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timer_dev_major=MAJOR(timer_dev_t);
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}
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if(ret<0)
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{
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printk("can't get major %d\n",timer_dev_major);
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return ret;
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}
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//-----------------------------------------------------------
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timer_dev=kmalloc(sizeof(struct TIMER_DEV),GFP_KERNEL);
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memset(timer_dev,0,sizeof(struct TIMER_DEV));
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cdev_init(&(timer_dev->cdev),&timer_ops);
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cdev_add(&(timer_dev->cdev),timer_dev_t,1);
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printk("init timer_dev success\n");
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return 0;
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-
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}
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static void __exit timer_exit(void)
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{
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kfree(timer_dev);
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cdev_del(&(timer_dev->cdev));
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unregister_chrdev_region(MKDEV(TIMER_MAJOR,0),1);
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}
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module_init(timer_init);
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module_exit(timer_exit);
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