forth_drv.c驅動源碼：

#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 *forthdrv_class;

volatile unsigned long *gph2con;

volatile unsigned long *gph2dat;

volatile unsigned long *gph3con;

volatile unsigned long *gph3dat;

static DECLARE_WAIT_QUEUE_HEAD(button_waitq);

// 中斷事件標志, 中斷服務程序將它置1，forth_drv_read將它清0 

static volatile int ev_press = 0;

struct pin_desc{

    unsigned int pin;

    unsigned int key_val;

};

// 鍵值: 按下時, 0x01, 0x02, 0x03, 0x04, 0x05 

// 鍵值: 松開時, 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},

};

// 確定按鍵值

static irqreturn_t buttons_irq(int irq, void *dev_id)

{

    struct pin_desc * pindesc = (struct pin_desc *)dev_id;

    unsigned int pinval;

    pinval = gpio_get_value(pindesc->pin);

    if (pinval)

    {

        // 松開 

        key_val = 0x80 | pindesc->key_val;

    }

    else

    {

        // 按下 

        key_val = pindesc->key_val;

    }

    ev_press = 1;                                                // 表示中斷發生了 

    wake_up_interruptible(&button_waitq);   // 喚醒休眠的進程 

    return IRQ_RETVAL(IRQ_HANDLED);

}

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

{

    // 注冊中斷 

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

{

    if (size != 1)

        return -EINVAL;

    // 如果沒有按鍵動作, 休眠 

    wait_event_interruptible(button_waitq, ev_press);

    // 如果有按鍵動作, 返回鍵值 

    copy_to_user(buf, &key_val, 1);

    ev_press = 0;

    return 1;

}

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

{

    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]);

    return 0;

}

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

{

    unsigned int mask = 0;

    poll_wait(file, &button_waitq, wait); // 不會立即休眠

    if (ev_press)

        mask |= POLLIN | POLLRDNORM;

    return mask;

}

static struct file_operations sencod_drv_fops = {

    .owner   =  THIS_MODULE,    // 這是一個宏，推向編譯模塊時自動創建的__this_module變量 

    .open     =  forth_drv_open,     

    .read      =  forth_drv_read,       

    .release  =  forth_drv_close,

    .poll       =  forth_drv_poll,

};

int major;

static int forth_drv_init(void)

{

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

    forthdrv_class = class_create(THIS_MODULE, "forth_drv");

    device_create(forthdrv_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 forth_drv_exit(void)

{

    unregister_chrdev(major, "forth_drv");

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

    class_destroy(forthdrv_class);

    iounmap(gph2con);

    iounmap(gph3con);

    return 0;

}

module_init(forth_drv_init);

module_exit(forth_drv_exit);

MODULE_LICENSE("GPL");

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

forthdrvtest.c測試源碼：

#include "sys/types.h"

#include "sys/stat.h"

#include "fcntl.h"

#include "stdio.h"

#include "poll.h"

// forthdrvtest 

int main(int argc, char **argv)

{

    int fd;

    unsigned char key_val;

    int ret;

    struct pollfd fds[1];

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

    if (fd < 0)

    {

        printf("can't open!\n");

    }

    fds[0].fd     = fd;

    fds[0].events = POLLIN;

    while (1)

    {

        ret = poll(fds, 1, 5000);

        if (ret == 0)

        {

            printf("time out\n");

        }

        else

        {

            read(fd, &key_val, 1);

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

        }

    }

    return 0;

}