一：为了消抖，笔者学习了Linux驱动之定时器API(参考 LDD定时器API （p198）)
定时器相关结构：
struct timer_list{
/*…省略一些字段…*/struct list_head list; //双向链表头，用来将多个定时器连成一个双向链表unsigned long expires;//定时有效时间void (*function)(unsigned long);//定时器处理函数unsigned long data；//此成员传给处理函数的参数
}；
相关函数：
void init_timer(struct timer_list *timer);//初始化定时器
void add_timer(struct timer_list *timer);//设置定时器
void del_timer（struct timer_list *timer）;//删除定时器
二代码：
/*
***************************************************************************
* Ralink Tech Inc.
* 4F, No. 2 Technology 5th Rd.
* Science-based Industrial Park
* Hsin-chu, Taiwan, R.O.C.
*
* (c) Copyright, Ralink Technology, Inc.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* THIS SOFTWARE IS PROVIDED ``AS IS‘‘ AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
* NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 675 Mass Ave, Cambridge, MA 02139, USA.
*
*
***************************************************************************
*/
#ifndef __RALINK_GPIO_H__
#define __RALINK_GPIO_H__
#include <linux/init.h>
#include <linux/version.h>
#include <linux/module.h>
#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/poll.h>
#include <linux/interrupt.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <linux/platform_device.h>
#include <linux/cdev.h>
#include <linux/miscdevice.h>
#include <linux/mutex.h>
#include <asm/mach-ralink/surfboardint.h>
//The Kenel header file, include soc virtual address
#include <asm/mach-ralink/rt_mmap.h>
#define RALINK_SYSCTL_ADDR RALINK_SYSCTL_BASE // system control
#define RALINK_REG_GPIOMODE (RALINK_SYSCTL_ADDR + 0x60) //GPIO MODE
#define RALINK_PRGIO_ADDR RALINK_PIO_BASE // Programmable I/O
#define RALINK_REG_PIO7140INT (RALINK_PRGIO_ADDR + 0x60)//中断地址
#define RALINK_REG_PIO7140EDGE (RALINK_PRGIO_ADDR + 0x64)//边沿触发方式地址
#define RALINK_REG_PIO7140RENA (RALINK_PRGIO_ADDR + 0x68)//上升沿触发掩码
#define RALINK_REG_PIO7140FENA (RALINK_PRGIO_ADDR + 0x6C)
#define RALINK_REG_PIO7140DATA (RALINK_PRGIO_ADDR + 0x70) //数据地址
#define RALINK_REG_PIO7140DIR (RALINK_PRGIO_ADDR + 0x74) //方向地址
#define RALINK_IRQ_ADDR RALINK_INTCL_BASE
#define RALINK_REG_INTENA (RALINK_IRQ_ADDR + 0x34)//enable 中断地址
#define RALINK_REG_INTDIS (RALINK_IRQ_ADDR + 0x38)//disable 中断地址
#endif
//实际引脚是:GE2_R XD1, 对应GPIO67
#include "key_driver.h"
#define KEY_DRIVER_NAME "key_driver"
//保存当前中断方式
static u32 ralink_gpio7140_intp = 0;
//保存当前边沿触发方式
static u32 ralink_gpio7140_edge = 0;
//gpio状态
typedef enum
{
e_gpio_rising = 0,
e_gpio_falling,
e_gpio_edge_unknow
}e_gpio_edge_t;
//gpio对应信息
struct gpio_status
{
int gpio_num;
e_gpio_edge_t edge;
u32 key_value;//键值传给用户空间
struct timer_list timer;//定时器(用于去抖)
};
static struct gpio_status g_gpio67 = {67, e_gpio_edge_unknow, 0};
//生成一个等待队列头wait_queue_head_t,名字为key_waitq
/* 等待队列:
* 当没有按键被按下时，如果有进程调用key_driver_read函数，
* 它将休眠
*/
static DECLARE_WAIT_QUEUE_HEAD(key_waitq);
/* 中断事件标志, 中断服务程序将它置1，key_driver_read将它清0*/
static volatile int ev_press = 0;
/**
* 设置gpio60-gpio71模式为gpio.
*/
static void set_7160_gpio_mode(void)
{
u32 gpiomode;
gpiomode = le32_to_cpu(*(volatile u32 *)(RALINK_REG_GPIOMODE));
gpiomode |= (0x1<<10);
*(volatile u32 *)(RALINK_REG_GPIOMODE) = cpu_to_le32(gpiomode);
}
/**
* 设置gpio40-gpio71的数据方向.(按键设置gpio67为输入)
*/
static void set_7140_dir(int gpio,int dir)
{
u32 gpiomode;
gpiomode = le32_to_cpu(*(volatile u32 *)(RALINK_REG_PIO7140DIR));
gpiomode &= ~(0x01<<(gpio-40));
gpiomode |= (dir?0x01:0x0)<<(gpio-40);
*(volatile u32 *)(RALINK_REG_PIO7140DIR) = cpu_to_le32(gpiomode);
}
//读取gpio67引脚的数据
/*static int read_gpio_data(int gpio)
{
unsigned long tmp;
tmp = le32_to_cpu(*(volatile u32 *)(RALINK_REG_PIO7140DATA));
return (tmp&(0x1<<(gpio-40))) ? 1 : 0 ;
}*/
//设置pio enable interrupt
static void enable_intp(void)
{
//在rt_mmap.h头文件中定义RALINK_INTCTL_PIO ，即第六位控制pio中断
//#define RALINK_INTCTL_PIO (1<<6)
*(volatile u32 *)(RALINK_REG_INTENA) = cpu_to_le32(RALINK_INTCTL_PIO);
}
//设置pio disable interrupt
static void disable_intp(void)
{
//在rt_mmap.h头文件中定义RALINK_INTCTL_PIO ，即第六位控制pio中断
//#define RALINK_INTCTL_PIO (1<<6)
*(volatile u32 *)(RALINK_REG_INTDIS) = cpu_to_le32(RALINK_INTCTL_PIO);
}
//set Edge Interrupt
static void gpio_reg_irq(int irq)
{
unsigned long tmp;
tmp = le32_to_cpu(*(volatile u32 *)(RALINK_REG_PIO7140RENA));
tmp |= (0x1 << (irq-40));
*(volatile u32 *)(RALINK_REG_PIO7140RENA) = cpu_to_le32(tmp);
/*tmp = le32_to_cpu(*(volatile u32 *)(RALINK_REG_PIO7140FENA));
tmp |= (0x1 << (irq-40));
*(volatile u32 *)(RALINK_REG_PIO7140FENA) = cpu_to_le32(tmp);*/
}
//先保存当前中断及触发寄存器的值,再清空
static void ralink_gpio7140_save_clear_intp(void)
{
//保存当前中断寄存器数据
ralink_gpio7140_intp = le32_to_cpu(*(volatile u32 *)(RALINK_REG_PIO7140INT));
//保存当前边沿触发方式
ralink_gpio7140_edge = le32_to_cpu(*(volatile u32 *)(RALINK_REG_PIO7140EDGE));
*(volatile u32 *)(RALINK_REG_PIO7140INT) = cpu_to_le32(0xFFFFFFFF);
*(volatile u32 *)(RALINK_REG_PIO7140EDGE) = cpu_to_le32(0xFFFFFFFF);
}
//扫描时候是gpio67被按下
static int scan_gpio_num(void)
{
if(!(ralink_gpio7140_intp & (1<<(g_gpio67.gpio_num - 40))))
{
printk("Have no key pressed...\n");
return -1;
}
if (ralink_gpio7140_edge & (1<<(g_gpio67.gpio_num - 40))) {
printk("set gpio value..\n");
g_gpio67.edge = e_gpio_rising;
g_gpio67.key_value = 1;
//上升沿才有效，具体需要根据硬件设计。
}
else {
printk("Have no edag...\n");
return -1;
}
return 0;
}
//打开设备
static int key_driver_open(struct inode *inode, struct file *file)
{
set_7160_gpio_mode(); //set RGMII2_GPIO_MODE to gpio mode.pro.p38
set_7140_dir(0x01<<(67-40),0); //set gpio60-gpio63 to gpin.
enable_intp(); //set pio enable interrupt
gpio_reg_irq(67); //set Edge Interrupt
return 0;
}
//关闭设备
static int key_driver_close(struct inode *inode, struct file *file)
{
disable_intp();
//禁止中断
return 0;
}
static int key_driver_read(struct file *filp, char __user *buff, size_t count, loff_t *offp)
{
unsigned long err;
if(!ev_press) {
if(filp->f_flags & O_NONBLOCK)
return -EAGAIN;
else//由wake_up_interruptible等待中断
wait_event_interruptible(key_waitq, ev_press);
}
ev_press = 0;
err = copy_to_user(buff, (const void *)&g_gpio67.key_value, sizeof(g_gpio67.key_value));
g_gpio67.edge = e_gpio_edge_unknow;
g_gpio67.key_value = 0x0;
return err ? -EFAULT : sizeof(g_gpio67.key_value);
}
long key_driver_ioctl(struct file *filp, unsigned int req, unsigned long arg)
{
return 0;
}
static unsigned int key_driver_poll( struct file *file, struct poll_table_struct *wait)
{
unsigned int mask = 0;
/*把调用poll 或者select 的进程挂入队列，以便被驱动程序唤醒*/
/*需要注意的是这个函数是不会引起阻塞的*/
poll_wait(file, &key_waitq, wait);
if(ev_press)
mask |= POLLIN | POLLRDNORM;
return mask;
}
static struct file_operations key_fops =
{
.owner = THIS_MODULE,
.open = key_driver_open,
.release = key_driver_close,
.read = key_driver_read,
.unlocked_ioctl = key_driver_ioctl,
.poll = key_driver_poll,
};
static struct miscdevice key_misc =
{
.minor = MISC_DYNAMIC_MINOR,
.name = KEY_DRIVER_NAME,
.fops = &key_fops,
};
static void key_timer_handler(unsigned long data)
{
ev_press = 1; /*设置中断标志为1*/
wake_up_interruptible(&key_waitq); /*唤醒等待队列*/
del_timer(&(g_gpio67.timer));
printk("interrupt wake up...\n");
}
//中断处理函数
/*关于中断处理函数的返回值:中断程序的返回值是一个特殊类型—irqreturn_t。
中断程序的返回值却只有两个: IRQ_NONE和IRQ_HANDLED。*/
static irqreturn_t ralink_key_interrupt(int irq, void *irqaction)
{
int ret;
printk("interrupt handler...\n");
//先保存当前中断及触发寄存器的值,再清空
ralink_gpio7140_save_clear_intp();
//查看是否是gpio67被按下
ret = scan_gpio_num();
//printk("Int func,gpio num %d.jiffies %ld,HZ %d\n",num,jiffies,HZ);
if(ret < 0)
return IRQ_RETVAL(IRQ_NONE);
//设置定时器10ms
init_timer(&(g_gpio67.timer));
g_gpio67.timer.expires = jiffies + HZ/100;//消抖时间为10ms
g_gpio67.timer.function = &key_timer_handler;
add_timer(&(g_gpio67.timer));
return IRQ_RETVAL(IRQ_HANDLED);
}
//初始化
static int __init key_driver_init(void)
{
int ret;
/*注册中断请求
中断号:SURFBOARDINT_GPIO
中断处理函数:ralink_key_interrupt
中断属性(方式):上升沿触发
使用此中断的设备:gpio_key
*/
ret = request_irq(SURFBOARDINT_GPIO, ralink_key_interrupt,
/*IRQF_DISABLED |*/ IRQ_TYPE_EDGE_RISING, "gpio_key", NULL);
if (ret)
return ret;
ret = misc_register(&key_misc);//初始化设备
printk("key_driver_init OK!\n");
return ret;
}
//退出
static void __exit key_driver_exit(void)
{
int ret;
free_irq(SURFBOARDINT_GPIO,NULL);//注销中断
ret = misc_deregister(&key_misc);//注销设置
if(ret < 0)
printk("key_driver_exit error.\n");
printk("key_driver_exit.\n");
}
module_init(key_driver_init);
module_exit(key_driver_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("XYH");
原文地址：http://www.cnblogs.com/xuyh/p/3909590.html
