For reasons unknown to me, the formatting in the flags doesn't produce the
effect promised by kerneldoc's documentation:
https://www.kernel.org/doc/html/latest/doc-guide/kernel-doc.html#return-values
* Serial interface for controlling RS485 settings on chips with suitable
* support. Set with TIOCSRS485 and get with TIOCGRS485 if supported by your
* platform. The set function returns the new state, with any unsupported bits
* reverted appropriately.
+ *
+ * serial_rs485::flags bits are:
+ * * %SER_RS485_ENABLED - RS485 enabled.
+ * * %SER_RS485_RTS_ON_SEND - Logical level for RTS pin when sending.
+ * * %SER_RS485_RTS_AFTER_SEND - Logical level for RTS pin after sent.
+ * * %SER_RS485_RX_DURING_TX - Full-duplex RS485 line.
+ * * %SER_RS485_TERMINATE_BUS - Enable bus termination (if supported).
+ * * %SER_RS485_ADDRB - Enable RS485 addressing mode.
+ * * %SER_RS485_ADDR_RECV - Receive address filter (enables @addr_recv).
+ * * Requires %SER_RS485_ADDRB.
+ * * %SER_RS485_ADDR_DEST - Destination address (enables @addr_dest).