原创 两个linux按键驱动之一 poll（未去抖动）

 err = copy_to_user(buff,(const void *)key_values,min(sizeof(key_values),count));
 memset((void *)key_values,0,sizeof(key_values));
 ev_press = 0;
 if(err)
  return -EFAULT;
 else
  return min(sizeof(key_values),count);
}
//buttons_poll
static unsigned int buttons_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 struct file_operations buttons_fops =
{
 .owner = THIS_MODULE,
 .open = buttons_open, /*open()*/
 .release = buttons_close, /*release()*/
 .read = buttons_read, /*read()*/
 .poll = buttons_poll /*poll()*/
};
struct cdev button_cdev;                       // cdev结构体
/* 初始化并注册cdev */
static void buttons_setup_cdev(void)
{
    int err,devno = MKDEV(button_major,0);
    cdev_init(&button_cdev,&buttons_fops);
    button_cdev.owner = THIS_MODULE;
    button_cdev.ops = &buttons_fops;
    err = cdev_add(&button_cdev, devno, 1);
    if (err)
        printk(KERN_NOTICE "Error %d adding utukey", err);
}
//init
static int __init buttons_init(void)
{
 int result;
 dev_t devno = MKDEV(button_major,0);    // 用主次设备号生成设备号
 
    /* 申请设备号 */
    if (button_major)
        result = register_chrdev_region(devno, 1, DEVICE_NAME);
    else    /* 动态申请设备号 */
    {
        result = alloc_chrdev_region(&devno, 0, 1, DEVICE_NAME);
        button_major = MAJOR(devno);
        printk(KERN_INFO "Todo: mknod /dev/%s c %d 0\n", DEVICE_NAME, button_major);
    } 
 if (result < 0)
        return result;
 
 buttons_setup_cdev();
 
 printk(DEVICE_NAME " initialized\n");
 return 0;
}
//buttons_exit()
static void __exit buttons_exit(void)
{
 cdev_del(&button_cdev);                             // 注销cdev
 unregister_chrdev_region(MKDEV(button_major, 0), 1);    // 释放设备号
}

module_init(buttons_init);
module_exit(buttons_exit);

MODULE_AUTHOR("http://www.xxx.net");
MODULE_DESCRIPTION("S3C2410/S3C2440 BUTTON Driver");
MODULE_LICENSE("GPL");

//测试代码

/*按键测试程序*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/select.h>
#include <sys/time.h>
#include <errno.h>

int main(void)
{
 int i;
 int buttons_fd;
 int key_value[6];
 fd_set rds;
 int ret;
 
 buttons_fd = open("/dev/buttons_my",0);
 if(buttons_fd < 0)
 {
  perror("open device buttons");
  exit(1);
 }

 while(1)
 {
  FD_ZERO(&rds);
  FD_SET(buttons_fd,&rds);

  ret = select(buttons_fd + 1,&rds,NULL,NULL,NULL);
  if(ret < 0)
  {
   perror("select");
   exit(1);
  }    
  if(ret == 0)
  {
   printf("Timeout.\n");
  }
  else if(FD_ISSET(buttons_fd,&rds))
  {
   int ret = read(buttons_fd,key_value,sizeof(key_value));
   if(ret != sizeof(key_value))
   {
    if(errno != EAGAIN)  
     perror("read buttons\n");
    continue;
   }
   else
   {
    for(i = 0; i < 6 ; i++)
    {
     if(key_value != 0)
      printf("You pressed buttons %d\n", key_value);
    }    
   }
  }
 }
 /*关闭设备*/
 close(buttons_fd);
 return 0;
}