Can't open ttyS0 !!!

Hi All !

I used 2s60ES and build uclinux for my board . I wrote simple example relate with UART this is my code :

struct termios options;

fd=open("/dev/ttyS0",O_RDWR );

if(fd==-1)

{

printf("Cannot open ttyS0!!\n");

exit(0);

}

fcntl(fd,F_SETFL,0);

tcgetattr(fd,&options);

options.c_cflag |=(CLOCAL | CREAD);

......

........

then I ran my example it CANNOT OPEN TTYS0 !!!!

thanks for help !