serial: max310x: honour rs485 properties from per-channel DT subnode

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The MAX310x DT binding pulls in /schemas/serial/rs485.yaml via its allOf
list, advertising the rs485-* properties defined there - none of which
were honoured at runtime, because the driver never called
uart_get_rs485_mode().

All channels share the parent SPI/I2C device, so uart_get_rs485_mode()
called directly on each port would read the same chip-level fwnode for
every call. Walk dev->of_node's children for the "serial@N" subnode
with matching reg, and temporarily retarget the parent device's fwnode
while uart_get_rs485_mode() runs, so each channel picks up its own
subnode's properties. Probe is serialised, so the swap is safe.

For single-channel variants (max3107, max3108), fall back to the chip's
own fwnode when no subnode is present, so existing DTs that declare
rs485 properties at the top level keep working.

Signed-off-by: Tapio Reijonen <tapio.reijonen@vaisala.com>
Link: https://patch.msgid.link/20260615-b4-max310x-rs485-dt-v3-3-7e79f064bdd7@vaisala.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Tapio Reijonen 2026-06-15 10:27:37 +00:00 • committed by Greg Kroah-Hartman

parent f3fd73bf20

commit bed094602f

1 changed files with 37 additions and 0 deletions

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drivers/tty/serial/max310x.c

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