按键驱动--定时器消抖

//buttons_timer.expires = 0;

add_timer(&buttons_timer);

major = register_chrdev(0, "key_drv", &key_drv_fops);

keydrv_class = class_create(THIS_MODULE, "key_drv");

keydrv_class_dev = class_device_create(keydrv_class, NULL, MKDEV(major, 0), NULL, "buttons");

// /dev/buttons

gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);

gpfdat = gpfcon + 1;

gpgcon = (volatile unsigned long *)ioremap(0x56000060, 16);

gpgdat = gpgcon + 1;

return 0;

}

static void key_drv_exit(void)

{

unregister_chrdev(major, "key_drv");

class_device_unregister(keydrv_class_dev);

class_destroy(keydrv_class);

iounmap(gpfcon);

iounmap(gpgcon);

return 0;

}

module_init(key_drv_init);

module_exit(key_drv_exit);

MODULE_LICENSE("GPL");

=================================================================

测试程序：

#include "sys/types.h"

#include "sys/stat.h"

#include "fcntl.h"

#include "stdio.h"

#include "poll.h"

#include "signal.h"

#include "sys/types.h"

#include "unistd.h"

#include "fcntl.h"

int fd;

void my_signal_fun(int signum)

{

unsigned char key_val;

read(fd, &key_val, 1);

printf("key_val: 0x%x\n", key_val);

}

int main(int argc, char **argv)

{

int ret;

fd = open("/dev/buttons", O_RDWR);

if(fd < 0)

{

printf("cant open!\n");

return -1;

}

while(1)

{

ret = read(fd, &key_val, 1);

printf("key_val:0x%x,ret = %d",key_val,ret);

//sleep(5);

}

return 0;

}

===============================================================

解析：

1、先定义一个定时器：static struct timer_list buttons_timer;

2、再在key_drv_init函数中初始化定时器：

init_timer(&buttons_timer);

buttons_timer.function = buttons_timer_function;

//buttons_timer.expires = 0;

add_timer(&buttons_timer);

3、在按键中断中设置定时器时间：

mod_timer(&buttons_timer,jiffies+HZ/100); //10ms以后启动定时器

4、如果没有二次中断修改中断时间则10ms以后就会进入定时器中断函数，处理定时器中断。