my_buttons.c文件：

#include

#include

#include

#include

#include

#include

#include

#define DEVICE_NAME     "mybuttons"

struct button_irq_desc {

    int irq;

    int pin;

    int pin_setting;

    int number;

    char *name;

};

#if !defined (CONFIG_QQ2440_BUTTONS)

static struct button_irq_desc button_irqs [] = {

    {IRQ_EINT8 , S3C2410_GPG0 ,  S3C2410_GPG0_EINT8  , 0, "KEY0"},

    {IRQ_EINT11, S3C2410_GPG3 ,  S3C2410_GPG3_EINT11 , 1, "KEY1"},

    {IRQ_EINT13, S3C2410_GPG5 ,  S3C2410_GPG5_EINT13 , 2, "KEY2"},

    {IRQ_EINT14, S3C2410_GPG6 ,  S3C2410_GPG6_EINT14 , 3, "KEY3"},

    {IRQ_EINT15, S3C2410_GPG7 ,  S3C2410_GPG7_EINT15 , 4, "KEY4"},

    {IRQ_EINT19, S3C2410_GPG11,  S3C2410_GPG11_EINT19, 5, "KEY5"},

};

#else /* means QQ */

static struct button_irq_desc button_irqs [] = {

    {IRQ_EINT19, S3C2410_GPG11, S3C2410_GPG11_EINT19, 0, "KEY0"},

    {IRQ_EINT11, S3C2410_GPG3,  S3C2410_GPG3_EINT11,  1, "KEY1"},

    {IRQ_EINT2,  S3C2410_GPF2,  S3C2410_GPF2_EINT2,   2, "KEY2"},

    {IRQ_EINT0,  S3C2410_GPF0,  S3C2410_GPF0_EINT0,   3, "KEY3"},

    {       -1,            -1,                 -1,    4, "KEY4"},

    {       -1,            -1,                 -1,    5, "KEY5"},

};

#endif

static volatile char key_values [] = {'0', '0', '0', '0', '0', '0'};

static DECLARE_WAIT_QUEUE_HEAD(button_waitq);

static volatile int ev_press = 0;

static irqreturn_t buttons_interrupt(int irq, void *dev_id)

{

    struct button_irq_desc *button_irqs = (struct button_irq_desc *)dev_id;

    int down;

    // udelay(0);

    down = !s3c2410_gpio_getpin(button_irqs->pin);

    if (down != (key_values[button_irqs->number] & 1)) { // Changed

key_values[button_irqs->number] = '0' + down;

        ev_press = 1;

        wake_up_interruptible(&button_waitq);

    }

    return IRQ_RETVAL(IRQ_HANDLED);

}

static int s3c24xx_buttons_open(struct inode *inode, struct file *file)

{

    int i;

    int err = 0;

    for (i = 0; i < sizeof(button_irqs)/sizeof(button_irqs[0]); i++) {

if (button_irqs[i].irq < 0) {

continue;

}

        err = request_irq(button_irqs[i].irq, buttons_interrupt, IRQ_TYPE_EDGE_BOTH, 

                          button_irqs[i].name, (void *)&button_irqs[i]);

        if (err)

            break;

    }

    if (err) {

        i--;

        for (; i >= 0; i--) {

    if (button_irqs[i].irq < 0) {

continue;

    }

    disable_irq(button_irqs[i].irq);

            free_irq(button_irqs[i].irq, (void *)&button_irqs[i]);

        }

        return -EBUSY;

    }

    ev_press = 1;

    return 0;

}

static int s3c24xx_buttons_close(struct inode *inode, struct file *file)

{

    int i;

    for (i = 0; i < sizeof(button_irqs)/sizeof(button_irqs[0]); i++) {

if (button_irqs[i].irq < 0) {

    continue;

}

free_irq(button_irqs[i].irq, (void *)&button_irqs[i]);

    }

    return 0;

}

static int s3c24xx_buttons_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

    wait_event_interruptible(button_waitq, ev_press);

    }

    ev_press = 0;

    err = copy_to_user(buff, (const void *)key_values, min(sizeof(key_values), count));

    return err ? -EFAULT : min(sizeof(key_values), count);

}

static struct file_operations dev_fops = {

    .owner   =   THIS_MODULE,

    .open    =   s3c24xx_buttons_open,

    .release =   s3c24xx_buttons_close, 

    .read    =   s3c24xx_buttons_read,

};

static struct miscdevice misc = {

.minor = MISC_DYNAMIC_MINOR,

.name = DEVICE_NAME,

.fops = &dev_fops,

};

static int __init dev_init(void)

{

int ret;

ret = misc_register(&misc);

printk (DEVICE_NAME"tinitializedn");

return ret;

}

static void __exit dev_exit(void)

{

misc_deregister(&misc);

}

module_init(dev_init);

module_exit(dev_exit);

MODULE_LICENSE("GPL");

MODULE_AUTHOR("FriendlyARM Inc.");

buttons_test.c文件：

#include

#include

int main(void)

{

int buttons_fd;

char buttons[6] = {'0', '0', '0', '0', '0', '0'};

buttons_fd = open("/dev/mybuttons", 0);

if (buttons_fd < 0) {

perror("open device buttons");

exit(1);

}

for (;;) {

char current_buttons[6];

int count_of_changed_key;

int i;

if (read(buttons_fd, current_buttons, sizeof current_buttons) != sizeof current_buttons) {

perror("read buttons:");

exit(1);

}

for (i = 0, count_of_changed_key = 0; i < sizeof buttons / sizeof buttons[0]; i++) {

if (buttons[i] != current_buttons[i]) {

buttons[i] = current_buttons[i];

printf("%skey %d is %s", count_of_changed_key? ", ": "", i+1, buttons[i] == '0' ? "up" : "down");

count_of_changed_key++;

}

}

if (count_of_changed_key) {

printf("n");

}

}

close(buttons_fd);

return 0;

}

实验步骤跟led驱动的编写步骤是一样的，具体可参考led驱动