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/*

* timer_demo.c -- An example to show timer_list's APIs.

*

* Copyright (C) 2015 hezhiping

* Version : Linux-2.6.32

*

* The source code in this file can be freely used, adapted,

* and redistributed in source or binary form, so long as an

* acknowledgment appears in derived source files.

*

*/

#include <linux/kernel.h> /* printk() */

#include <linux/module.h>

#include <linux/slab.h> /* for kmalloc() */

#include <linux/jiffies.h> /* for global var jiffies and HZ */

#include <linux/errno.h> /* error codes */

#include <linux/timer.h> /* for xxx_timer() */

struct my_data {

unsigned v1;

unsigned v2;

};

static struct my_data *data;

static struct timer_list timer;

static void timer_demo_timerout(unsigned long data)

{

struct my_data *dptr = (struct my_data *)data;

dptr->v1 += 1;

dptr->v2 += 1;

printk("In timer, v1=%d, v2=%d\n", dptr->v1, dptr->v2);

/* Step3. motify the timer

* int mod_timer(struct timer_list *timer, unsigned long expires)

*/

mod_timer(&timer, jiffies + 3 * HZ);

}

static int __init timer_demo_init_module(void)

{

data = kmalloc(sizeof(struct my_data), GFP_KERNEL);

if (!data) {

printk("kmalloc failed\n");

return -ENOMEM;

}

data->v1 = 0;

data->v2 = 1;

/* Step1. initial a timer

* void init_timer(struct timer_list * timer)

*/

init_timer(&timer);

timer.data = (unsigned long)data;

timer.function = timer_demo_timerout;

timer.expires = jiffies + 2 * HZ;

/* Step2. active the timer

* void add_timer(struct timer_list *timer)

*/

add_timer(&timer);

return 0;

}

static void __exit timer_demo_exit_module(void)

{

int ret;

/* Step4. delete the timer

* int del_timer_sync(struct timer_list * timer)

*/

ret = del_timer_sync(&timer);

if (ret == 0) {

printk("Timer was already deactived,"

"before call del_timer_sync()");

}

if (data)

kfree(data);

}

module_init(timer_demo_init_module);

module_exit(timer_demo_exit_module);

MODULE_AUTHOR("HeZhiping");

MODULE_LICENSE("Dual BSD/GPL");

MODULE_DESCRIPTION("A simple demo to show how to use timer_list");