buttons.c驱动源码：

#include "linux/device.h"

#include "linux/interrupt.h"

#include "linux/module.h"

#include "linux/kernel.h"

#include "linux/fs.h"

#include "linux/init.h"

#include "linux/delay.h"

#include "linux/irq.h"

#include "asm/uaccess.h"

#include "asm/irq.h"

#include "asm/io.h"

#include "mach/gpio.h"

#include "linux/poll.h"

static struct class *sixthdrv_class;

volatile unsigned long *gph2con;

volatile unsigned long *gph2dat;

volatile unsigned long *gph3con;

volatile unsigned long *gph3dat;

static struct timer_list buttons_timer;

static DECLARE_WAIT_QUEUE_HEAD(button_waitq);

// 中断事件标志, 中断服务程序将它置1，sixth_drv_read将它清0 

static volatile int ev_press = 0;

static struct fasync_struct *button_async;

struct pin_desc{

    unsigned int pin;

    unsigned int key_val;

};

// 键值: 按下时, 0x01, 0x02, 0x03, 0x04, 0x05 

// 键值: 松开时, 0x81, 0x82, 0x83, 0x84, 0x85 

static unsigned char key_val;

struct pin_desc pins_desc[5] = {

    {S5PV210_GPH2(3), 0x01},

    {S5PV210_GPH3(0), 0x02},

    {S5PV210_GPH3(1), 0x03},

    {S5PV210_GPH3(2), 0x04},

    {S5PV210_GPH3(3), 0x05},

};

static struct pin_desc *irq_pd;

//static atomic_t canopen = ATOMIC_INIT(1);     //定义原子变量并初始化为1

static DECLARE_MUTEX(button_lock);                 //定义互斥锁

// 确定按键值

static irqreturn_t buttons_irq(int irq, void *dev_id)

{

    // 10ms后启动定时器 

    irq_pd = (struct pin_desc *)dev_id;

    mod_timer(&buttons_timer, jiffies+HZ/100);

    return IRQ_RETVAL(IRQ_HANDLED);

}

static int sixth_drv_open(struct inode *inode, struct file *file)

{

#if 0    

    if (!atomic_dec_and_test(&canopen))

    {

        atomic_inc(&canopen);

        return -EBUSY;

    }

#endif        

    if (file->f_flags & O_NONBLOCK)

    {

        if (down_trylock(&button_lock))

            return -EBUSY;

    }

    else

    {

        // 获取信号量 

        down(&button_lock);

    }

    // 注册中断 

    request_irq(IRQ_EINT(19),  buttons_irq, IRQF_TRIGGER_FALLING|IRQF_TRIGGER_RISING, 

                        "K4", &pins_desc[0]);

    request_irq(IRQ_EINT(24),  buttons_irq, IRQF_TRIGGER_FALLING|IRQF_TRIGGER_RISING, 

                        "K5", &pins_desc[1]);

    request_irq(IRQ_EINT(25), buttons_irq, IRQF_TRIGGER_FALLING|IRQF_TRIGGER_RISING, 

                        "K6", &pins_desc[2]);

    request_irq(IRQ_EINT(26), buttons_irq, IRQF_TRIGGER_FALLING|IRQF_TRIGGER_RISING, 

                         "K7", &pins_desc[3]);    

    request_irq(IRQ_EINT(27), buttons_irq, IRQF_TRIGGER_FALLING|IRQF_TRIGGER_RISING, 

                         "K8", &pins_desc[4]);    

    return 0;

}

ssize_t sixth_drv_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)

{

    if (size != 1)

        return -EINVAL;

    if (file->f_flags & O_NONBLOCK)

    {

        if (!ev_press)

            return -EAGAIN;

    }

    else

    {

        // 如果没有按键动作, 休眠 

        wait_event_interruptible(button_waitq, ev_press);

    }

    // 如果有按键动作, 返回键值 

    copy_to_user(buf, &key_val, 1);

    ev_press = 0;

    return 1;

}

int sixth_drv_close(struct inode *inode, struct file *file)

{

    //atomic_inc(&canopen);

    free_irq(IRQ_EINT(19), &pins_desc[0]);

    free_irq(IRQ_EINT(24), &pins_desc[1]);

    free_irq(IRQ_EINT(25), &pins_desc[2]);

    free_irq(IRQ_EINT(26), &pins_desc[3]);

    free_irq(IRQ_EINT(27), &pins_desc[4]);

    up(&button_lock);

    return 0;

}

static unsigned sixth_drv_poll(struct file *file, poll_table *wait)

{

    unsigned int mask = 0;

    poll_wait(file, &button_waitq, wait); // 不会立即休眠

    if (ev_press)

        mask |= POLLIN | POLLRDNORM;

    return mask;

}

static int sixth_drv_fasync (int fd, struct file *filp, int on)

{

    printk("driver: sixth_drv_fasync\n");

    return fasync_helper (fd, filp, on, &button_async);

}

static struct file_operations sencod_drv_fops = {

    .owner   =  THIS_MODULE,    // 这是一个宏，推向编译模块时自动创建的__this_module变量 

    .open     =  sixth_drv_open,     

    .read      =  sixth_drv_read,       

    .release  =  sixth_drv_close,

    .poll       =  sixth_drv_poll,

    .fasync   =  sixth_drv_fasync,

};

int major;

static void buttons_timer_function(unsigned long data)

{

    struct pin_desc * pindesc = irq_pd;

    unsigned int pinval;

    if (!pindesc)

        return;

    pinval = gpio_get_value(pindesc->pin);

    if (pinval)

    {

        // 松开 

        key_val = 0x80 | pindesc->key_val;

    }

    else

    {

        // 按下 

        key_val = pindesc->key_val;

    }

    ev_press = 1;                                                // 表示中断发生了 

    wake_up_interruptible(&button_waitq);   // 唤醒休眠的进程 

    kill_fasync (&button_async, SIGIO, POLL_IN);

}

static int sixth_drv_init(void)

{

    init_timer(&buttons_timer);

    buttons_timer.function = buttons_timer_function;

    //buttons_timer.expires  = 0;

    add_timer(&buttons_timer); 

    major = register_chrdev(0, "sixth_drv", &sencod_drv_fops);

    sixthdrv_class = class_create(THIS_MODULE, "sixth_drv");

    device_create(sixthdrv_class, NULL, MKDEV(major, 0), NULL, "buttons"); // /dev/buttons 

    gph2con = (volatile unsigned long *)ioremap(0xe0200c40, 16);

    gph2dat = gph2con + 1;

    gph3con = (volatile unsigned long *)ioremap(0xE0200C60, 16);

    gph3dat = gph3con + 1;

    return 0;

}

static void sixth_drv_exit(void)

{

    unregister_chrdev(major, "sixth_drv");

    device_destroy(sixthdrv_class, MKDEV(major, 0));

    class_destroy(sixthdrv_class);

    iounmap(gph2con);

    iounmap(gph3con);

}

module_init(sixth_drv_init);

module_exit(sixth_drv_exit);

MODULE_LICENSE("GPL");

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

buttons_test.c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"

// sixthdrvtest 

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)

{

    unsigned char key_val;

    int ret;

    int Oflags;

    //signal(SIGIO, my_signal_fun);

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

    if (fd < 0)

    {

        printf("can't open!\n");

        return -1;

    }

    //fcntl(fd, F_SETOWN, getpid());

    //Oflags = fcntl(fd, F_GETFL); 

    //fcntl(fd, F_SETFL, Oflags | FASYNC);

    while (1)

    {

        ret = read(fd, &key_val, 1);

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

        //sleep(5);

    }

    return 0;

}