RDR               354 drivers/tty/synclink.c #define RDR	0x20	/* Receive Data Register */
RDR               393 drivers/tty/synclink_gt.c #define RDR   0x80 /* rx data */
RDR                31 drivers/usb/serial/io_16654.h #define RDR			0	// ! Receive Holding Register (Read)