buttons.c驱动源码：

// 参考drivers\input\keyboard\gpio_keys.c 

#include "linux/module.h"

#include "linux/version.h"

#include "linux/module.h"

#include "linux/init.h"

#include "linux/fs.h"

#include "linux/interrupt.h"

#include "linux/irq.h"

#include "linux/sched.h"

#include "linux/pm.h"

#include "linux/slab.h"

#include "linux/sysctl.h"

#include "linux/proc_fs.h"

#include "linux/delay.h"

#include "linux/platform_device.h"

#include "linux/input.h"

#include "linux/gpio_keys.h"

#include "linux/workqueue.h"

#include "linux/gpio.h"

struct pin_desc{

    int irq;

    char *name;

    unsigned int pin;

    unsigned int key_val;

};

struct pin_desc pins_desc[4] = {

    {IRQ_EINT(19), "K4", S5PV210_GPH2(3),  KEY_L},

    {IRQ_EINT(24), "K5", S5PV210_GPH3(0),  KEY_S},

    {IRQ_EINT(25), "K6", S5PV210_GPH3(1),  KEY_ENTER},

    {IRQ_EINT(26), "K7", S5PV210_GPH3(2),  KEY_LEFTSHIFT},

};

static struct input_dev *buttons_dev;

static struct pin_desc *irq_pd;

static struct timer_list buttons_timer;

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 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 : 最后一个参数: 0-松开, 1-按下 

        input_event(buttons_dev, EV_KEY, pindesc->key_val, 0);

        input_sync(buttons_dev);

    }

    else

    {

        // 按下 

        input_event(buttons_dev, EV_KEY, pindesc->key_val, 1);

        input_sync(buttons_dev);

    }

}

static int buttons_init(void)

{

    int i;

    // 1. 分配一个input_dev结构体 

    buttons_dev = input_allocate_device();;

    // 2. 设置 

    // 2.1 能产生哪类事件 

    set_bit(EV_KEY, buttons_dev->evbit);

    set_bit(EV_REP, buttons_dev->evbit);

    // 2.2 能产生这类操作里的哪些事件: L,S,ENTER,LEFTSHIT 

    set_bit(KEY_L, buttons_dev->keybit);

    set_bit(KEY_S, buttons_dev->keybit);

    set_bit(KEY_ENTER, buttons_dev->keybit);

    set_bit(KEY_LEFTSHIFT, buttons_dev->keybit);

    // 3. 注册 

    input_register_device(buttons_dev);

    // 4. 硬件相关的操作 

    init_timer(&buttons_timer);

    buttons_timer.function = buttons_timer_function;

    add_timer(&buttons_timer);

    for (i = 0; i < 4; i++)

    {

        request_irq(pins_desc[i].irq, buttons_irq, IRQF_TRIGGER_FALLING|IRQF_TRIGGER_RISING,

                            pins_desc[i].name, &pins_desc[i]);

    }

    return 0;

}

static void buttons_exit(void)

{

    int i;

    for (i = 0; i < 4; i++)

    {

        free_irq(pins_desc[i].irq, &pins_desc[i]);

    }

    del_timer(&buttons_timer);

    input_unregister_device(buttons_dev);

    input_free_device(buttons_dev);    

}

module_init(buttons_init);

module_exit(buttons_exit);

MODULE_LICENSE("GPL");