serial: core: Support common rs485 binding for RTS polarity
When a driver invokes the uart_get_rs485_mode() helper, set the RTS
polarity to active high by default unless the newly introduced
"rs485-rts-active-low" property was specified.
imx contains a line to set the default RTS polarity to active high,
it is now superfluous and hence deleted.
omap-serial historically defaults to active low and supports an
"rs485-rts-active-high" property to inverse the polarity.
Retain that behavior for compatibility.
Cc: Mark Jackson <mpfj@newflow.co.uk>
Cc: Michał Oleszczyk <oleszczyk.m@gmail.com>
Cc: Rafael Gago Castano <rgc@hms.se>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index a59184a..f57969de 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -3036,16 +3036,23 @@ void uart_get_rs485_mode(struct device *dev, struct serial_rs485 *rs485conf)
}
/*
- * clear full-duplex and enabled flags to get to a defined state with
- * the two following properties.
+ * Clear full-duplex and enabled flags, set RTS polarity to active high
+ * to get to a defined state with the following properties:
*/
- rs485conf->flags &= ~(SER_RS485_RX_DURING_TX | SER_RS485_ENABLED);
+ rs485conf->flags &= ~(SER_RS485_RX_DURING_TX | SER_RS485_ENABLED |
+ SER_RS485_RTS_AFTER_SEND);
+ rs485conf->flags |= SER_RS485_RTS_ON_SEND;
if (device_property_read_bool(dev, "rs485-rx-during-tx"))
rs485conf->flags |= SER_RS485_RX_DURING_TX;
if (device_property_read_bool(dev, "linux,rs485-enabled-at-boot-time"))
rs485conf->flags |= SER_RS485_ENABLED;
+
+ if (device_property_read_bool(dev, "rs485-rts-active-low")) {
+ rs485conf->flags &= ~SER_RS485_RTS_ON_SEND;
+ rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
+ }
}
EXPORT_SYMBOL_GPL(uart_get_rs485_mode);
