（1）全域性變數
jiffies：記錄了系統啟動以來，經過了多少tick，初始值為0。乙個tick代表多長時間，在核心的config_hz中定義。比如config_hz=200，則乙個jiffies對應5ms時間。
hz：系統定時器每秒產生中斷的頻率，/arch/arm/include/asm/param.h中定義。
（2）函式
//include/linux/timer.h
struct timer_list
;void
init_timer
(struct timer_list *timer )
;//初始化
add_timer
(struct timer_list*
)//新增定時器
mod_timer
(struct timer_list *
,unsigned
long jiffier_timerout)
//新的定時值
del_timer
(struct timer_list*
)//刪除定時器
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
static
struct class *buttons_class;
static
struct class_device *buttons_class_dev;
static
struct fasync_struct *button_async;
static
declare_wait_queue_head
(button_waitq)
;/* 中斷事件標誌, 中斷服務程式將它置1，forth_drv_read將它清0 */
static
volatile
int ev_press =0;
struct pin_desc
;static
struct timer_list buttons_timer;
static
struct pin_desc *irq_dev_id;
/* 鍵值: 按下時, 0x01, 0x02, 0x03, 0x04 */
/* 鍵值: 鬆開時, 0x81, 0x82, 0x83, 0x84 */
static
unsigned
char key_val;
/* * k1,k2,k3,k4對應gpg0，gpg3，gpg5，gpg6
*/struct pin_desc pins_desc[4]
=,,,
,};/*
* 確定按鍵值
*/static irqreturn_t buttons_irq
(int irq,
void
*dev_id)
static
intbuttons_drv_open
(struct inode *inode,
struct file *file)
ssize_t buttons_drv_read
(struct file *file,
char __user *buf, size_t size, loff_t *ppos)
intbuttons_drv_close
(struct inode *inode,
struct file *file)
static
unsigned
buttons_drv_poll
(struct file *file, poll_table *wait)
static
intbuttons_fasync
(int fd,
struct file *file,
int on)
static
struct file_operations buttons_drv_fops =
;static
void
buttons_timer_fun
(long data)
pinval =
s3c2410_gpio_getpin
(irq_dev_id->pin);if
(pinval)
else
ev_press =1;
/* 表示中斷發生了 */
wake_up_interruptible
(&button_waitq)
;/* 喚醒休眠的程序 */
kill_fasync
(&button_async, sigio, poll_in);}
int major;
static
intbuttons_drv_init
(void
)static
void
buttons_drv_exit
(void
)module_init
(buttons_drv_init)
;module_exit
(buttons_drv_exit)
;module_license
("gpl"
);
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