serial: core: move RS485 configuration tasks from drivers into core
Several drivers that support setting the RS485 configuration via userspace
implement one or more of the following tasks:
- in case of an invalid RTS configuration (both RTS after send and RTS on
send set or both unset) fall back to enable RTS on send and disable RTS
after send
- nullify the padding field of the returned serial_rs485 struct
- copy the configuration into the uart port struct
- limit RTS delays to 100 ms
Move these tasks into the serial core to make them generic and to provide
a consistent behaviour among all drivers.
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Link: https://lore.kernel.org/r/20220410104642.32195-2-LinoSanfilippo@gmx.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>