USB: serial: mxuport: support RS485 mode configuration

Add support for TIOCSRS485 and TIOCGRS485 so that userspace can
configure the serial interface mode using struct serial_rs485.

Map the serial_rs485 flags to the device interface modes as follows:

  - RS232                  = no flags set
  - RS422                  = SER_RS485_ENABLED | SER_RS485_MODE_RS422
  - RS485_2W (half-duplex) = SER_RS485_ENABLED
  - RS485_4W (full-duplex) = SER_RS485_ENABLED | SER_RS485_RX_DURING_TX

Unsupported flags and fields are cleared before applying the
configuration. Cache the sanitized per-port configuration and serialize
access with the per-port mutex.

Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
Signed-off-by: Johan Hovold <johan@kernel.org>

0 files changed, 0 insertions, 0 deletions