how to detect my gpio keyboard?

[lanmanck]

hi all:
i have read this post:
w w w.at91. c o m/samphpbb/viewtopic.php?f=12&t=3255&start=0&st=0&sk=t&sd=a
now my driver works fine, in the interrupt routine i report the key:
IN KERNEL:
input_report_key(keyboard, kbd_t.lastkey, KEY_IS_DOWN);
input_report_key(keyboard, kbd_t.lastkey, KEY_IS_UP);
input_sync(keyboard);

when i printk it ,the value is correct (only support press one gpio at a time);

Now,i want to detect it in my application,i use these code:

int main(int argc, char **argv)
{
   int keyboard;
   int ret,i;
   char c;
   fd_set readfd;
   struct timeval timeout;
   keyboard = open("/dev/event0",O_RDONLY | O_NONBLOCK);
   assert(keyboard>0);
   
   while(1)
   {   
      timeout.tv_sec=2;
      timeout.tv_usec=0;
      FD_ZERO(&readfd);
      FD_SET(keyboard,&readfd);
      ret=select(keyboard+1,&readfd,NULL,NULL,&timeout);//NULL
      if(ret < 0) perror("select");
      else if(ret == 0) printf("time out\n");
      else
      {
         printf("ret=%d\n", ret);  //always enter here!!!
         if(FD_ISSET(keyboard,&readfd))
         {
            i=read(keyboard,&c,1);
            if('\n'==c)
               continue;
            printf("input is %c,%d\n",c,c);
   
            if ('q'==c)
               break;
         }
      }
   }
   close(keyboard);
   return 0;
}

i run this code,when i donot press the gpio,it seems to work OK,that's say:
the terminal will print "time out" every 2 second.
HOWEVER,when i press the gpio (and release),it always runs to last "else":
ret=1
input is ,0
ret=1
input is ,0
ret=1
input is ,0
ret=1
input is ,0
and do not STOP again.Why these happen?
BY THE WAY,can i use the gpio button to emulate a tty keyboard? I mean i can use "getchar()" through my application :)
your quick reply is appreciated!