Linux内核模块 时间定时器API 实例

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/timer.h>

static struct timer_list my_timer;

static void my_timer_callback(struct timer_list *timer)
{
    printk("%s called (%ld)\n", __func__, jiffies);
    
    //再次添加2秒的定时器任务, 可以用来反复检测温度之类
    mod_timer(&my_timer, jiffies + msecs_to_jiffies(2000));
}

static int __init my_init(void)
{
    int ret;
    
    pr_info("%s: Timer module loaded\n", __func__);
    
    //初始化timer_list数据结构
    //注册了回调函数my_timer_callback
    timer_setup(&my_timer, my_timer_callback, 0);   
    pr_info("%s: Setup timer to fire in 2s (%ld)\n", __func__, jiffies);

    //设置延时多长时间, 2000毫秒后调用回调函数
    ret = mod_timer(&my_timer, jiffies + msecs_to_jiffies(2000));
    if (ret)
        pr_err("%s: Timer firing failed\n", __func__);
    
    return 0;
}

static void __exit my_exit(void)
{
    int ret;
    
    //删除定时器
    ret = del_timer(&my_timer);
    if (ret)
        pr_err("%s: The timer is still is use ...\n", __func__);
    
    pr_info("%s: Timer module unloaded\n", __func__);
}

module_init(my_init);
module_exit(my_exit);
MODULE_AUTHOR("Yannik Li <yannik520@gmail.com>");
MODULE_DESCRIPTION("Timer example");
MODULE_LICENSE("GPL");