#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>

[...]

irqreturn_t
irq_myhandler (int irqn, void *dev)
{
       printk (KERN_INFO "Key pressed...\n");
       return IRQ_HANDLED;
}

int
init_module ()
{
       int res;
       printk (KERN_INFO "Hello World!\n");
       free_irq (1, NULL);
       res = request_irq (1, irq_myhandler, IRQF_SHARED, "bao", dev_id);
       printk (KERN_INFO "res: %d\n", res);
       return 0;
}

void
cleanup_module ()
{
       free_irq (1, NULL);
       printk (KERN_INFO "Goodbye World!\n");
}