init_timer(&timer);   　　　　　　　　//定时器初始化
  timer.data=http://www.mamicode.com/10;        　　　　　　　　//设置超时处理函数参数
  timer.expires=jiffies+(10*HZ);   　 //设置超时jiffies值为10s  
  timer.function=timer_func; 　　　　　//设置超时处理函数
  add_timer(&timer);      　　　　　　 //添加定时器到内核
  del_timer(&timer);   　　　　　　　　 //删除定时器  在每次调用之前应该把上次调用的删除

#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/random.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/wait.h>
#include <linux/mutex.h>
#include <linux/io.h>
#include <asm/irq.h>
#include <linux/irq.h>
#include <linux/fs.h>
#include <asm/arch/regs-gpio.h>
#include <linux/interrupt.h>
#include <linux/poll.h>

static struct class *key_class;     //创建类
static struct class_device *key_class_devs;   //创建类对应的设备
static struct timer_list keys_timer;

struct pin_desc{
    unsigned int pin;
    unsigned int key_val;
};
struct pin_desc pins_desc[4] = {
    {S3C2410_GPF0,0X01},
    {S3C2410_GPF2,0X02},
    {S3C2410_GPG3,0X03},
    {S3C2410_GPG11,0X04},
};

struct pin_desc *pin_timer;　　　　//在按键中断里保存按下按键的信息
unsigned char keyvals=0;

static volatile int ev_press = 0;
static DECLARE_WAIT_QUEUE_HEAD(button_waitq);

static struct fasync_struct *key_async_queue;

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

static irqreturn_t keys_irq(int irq, void *dev_id)
{
    pin_timer = (struct pin_desc *)dev_id;
    mod_timer(&keys_timer, jiffies+HZ/100 );　　//jiffies是个全局变量，每10ms累加一次，这里是10ms产生一次中断
    return IRQ_HANDLED;
}


int key_open(struct inode *inode, struct file *fp)
{
    /*获取信号量*/
    if( fp->f_flags & O_NONBLOCK )
    {
        if(down_trylock(&canopen))
            return -EBUSY;
    }
    else
    {
        down(&canopen);
    }
    request_irq( IRQ_EINT0, keys_irq, IRQT_BOTHEDGE, "key2", &pins_desc[0]);
    request_irq( IRQ_EINT2, keys_irq, IRQT_BOTHEDGE, "key3", &pins_desc[1]);
    request_irq( IRQ_EINT11, keys_irq, IRQT_BOTHEDGE, "key4", &pins_desc[2]);
    request_irq( IRQ_EINT19, keys_irq, IRQT_BOTHEDGE, "key5", &pins_desc[3]);
    return 0;
}

ssize_t key_read(struct file *fp, char __user *buff, size_t count, loff_t *offp){

    if(fp->f_flags & O_NONBLOCK )
    {
        if(!ev_press)
            return -EAGAIN;
    }
    else
    {
        wait_event_interruptible(button_waitq,ev_press);
    }
    if(count != 1)
    {
        return -EINVAL;
    }
    
    copy_to_user(buff,&keyvals,1);
    ev_press = 0;
    return 0;
}

ssize_t key_write(struct file *fp, const char __user *buf, size_t count, loff_t *ppos){
}

int key_close(struct inode *inode, struct file *file)
{
    free_irq(IRQ_EINT0,&pins_desc[0]);
    free_irq(IRQ_EINT2,&pins_desc[1]);
    free_irq(IRQ_EINT11,&pins_desc[2]);
    free_irq(IRQ_EINT19,&pins_desc[3]);
    up(&canopen);
}

static unsigned int key_poll(struct file *file, struct poll_table_struct *wait)
{
    unsigned int mask = 0;
    poll_wait(file, &button_waitq,wait);
    if(ev_press)
        mask |= POLLIN|POLLRDNORM;
    return mask;
}

static int key_fsync (int fd, struct file *filp, int on)
{
    printk("ok\n");
    return fasync_helper (fd, filp, on, &key_async_queue);
}

struct file_operations led_fops={
    .owner = THIS_MODULE,
    .open = key_open,
    .write  = key_write,
    .read   = key_read,
    .release = key_close,
    .poll = key_poll,
    .fasync = key_fsync,
};

static void keys_timer_fun(unsigned long t)
{
    struct pin_desc *pindesc = (struct pin_desc *)pin_timer;
    unsigned int pinval;
    if( !pindesc )
        return ;
    pinval = s3c2410_gpio_getpin(pindesc->pin);
    if(pinval)
    {
        keyvals = pindesc->key_val|0x80;
            
    }
    else
    {
        keyvals = pindesc->key_val;
    }
    ev_press = 1;
    wake_up_interruptible(&button_waitq);

    kill_fasync (&key_async_queue, SIGIO, POLL_IN);
    return ;
}

int major;
static int key_init(void)
{
    major = register_chrdev( 0,"key_drv", &led_fops );
    key_class = class_create(THIS_MODULE,"key_class");
    key_class_devs = class_device_create(key_class,NULL,MKDEV(major,0),NULL,"my_keys");
   
    init_timer(&keys_timer);
    keys_timer.function = keys_timer_fun;    /*定时器中断函数*/
    keys_timer.expires = 0;
    add_timer(&keys_timer);
    printk("key install Module\n");
    return 0;
}

static void key_exit(void)
{
    unregister_chrdev( major, "key_drv" );
    class_device_unregister(key_class_devs);
    class_destroy(key_class);
 　　del_timer(&keys_timer);　　　　//删除定时器
   　printk("key Module exit\n");
}

module_init(key_init);
module_exit(key_exit);
MODULE_LICENSE("GPL");

#include <stdio.h>
#include <signal.h>
#include <fcntl.h>
#include <unistd.h>
int fd;
static char key_val;
int main( int argc, char **argv )
{
    int oflags;
    fd = open("/dev/my_keys",O_RDWR);/* O_NONBLOCK为非阻塞*/
    if(fd<0)
    {
        printf("open failed\n");
        return 0;
    }
    while(1)
    {
        read(fd,&key_val,1);
        printf("key_val:%d\n",key_val);
    }
    return 0;
}