RS-485 in half-duplex mode

Hello list, I try to use a RS-485 Interface with two wires on a imx28 CPU. Using the driver in mxs-auart.c. I already modified my device tree to use AUART4_RX and AUART4_TX for sending and receiving. This is working so far. But since it is half-duplex the question arises how the switching between sending and receiving is done. I have AUART4_RTS (GPIO2_26) for this purpose. Is this something the driver can handle? do I have to adjust my device tree or the driver for this setup? It is necessary to handle this via IOCTL(TIOCSRS485) from user space? Best Regards, Oliver