serial: Deduplicate rs485 sanitization

Signed-off-by: Lukas Wunner <lukas@wunner.de>

Author: l1k

drivers/tty/serial/8250/8250_port.c

@@ -673,20 +673,10 @@ int serial8250_em485_config(struct uart_port *port, struct serial_rs485 *rs485)
 {
 	struct uart_8250_port *up = up_to_u8250p(port);
 
-	/* pick sane settings if the user hasn't */
-	if (!!(rs485->flags & SER_RS485_RTS_ON_SEND) ==
-	    !!(rs485->flags & SER_RS485_RTS_AFTER_SEND)) {
-		rs485->flags |= SER_RS485_RTS_ON_SEND;
-		rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
-	}
-
-	/* clamp the delays to [0, 100ms] */
-	rs485->delay_rts_before_send = min(rs485->delay_rts_before_send, 100U);
-	rs485->delay_rts_after_send  = min(rs485->delay_rts_after_send, 100U);
-
-	memset(rs485->padding, 0, sizeof(rs485->padding));
 	port->rs485 = *rs485;
 
+	uart_sanitize_rs485_mode(port);
+
 	gpiod_set_value(port->rs485_term_gpio,
 			rs485->flags & SER_RS485_TERMINATE_BUS);
 

drivers/tty/serial/amba-pl011.c

@@ -2170,22 +2170,12 @@ static int pl011_rs485_config(struct uart_port *port,
 	struct uart_amba_port *uap =
 		container_of(port, struct uart_amba_port, port);
 
-	/* pick sane settings if the user hasn't */
-	if (!(rs485->flags & SER_RS485_RTS_ON_SEND) ==
-	    !(rs485->flags & SER_RS485_RTS_AFTER_SEND)) {
-		rs485->flags |= SER_RS485_RTS_ON_SEND;
-		rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
-	}
-	/* clamp the delays to [0, 100ms] */
-	rs485->delay_rts_before_send = min(rs485->delay_rts_before_send, 100U);
-	rs485->delay_rts_after_send = min(rs485->delay_rts_after_send, 100U);
-	memset(rs485->padding, 0, sizeof(rs485->padding));
-
 	if (port->rs485.flags & SER_RS485_ENABLED)
 		pl011_rs485_tx_stop(uap);
 
 	/* Set new configuration */
 	port->rs485 = *rs485;
+	uart_sanitize_rs485_mode(port);
 
 	/* Make sure auto RTS is disabled */
 	if (port->rs485.flags & SER_RS485_ENABLED) {
@@ -2662,16 +2652,13 @@ static int pl011_find_free_port(void)
 static int pl011_get_rs485_mode(struct uart_amba_port *uap)
 {
 	struct uart_port *port = &uap->port;
-	struct serial_rs485 *rs485 = &port->rs485;
 	int ret;
 
 	ret = uart_get_rs485_mode(port);
 	if (ret)
 		return ret;
 
-	/* clamp the delays to [0, 100ms] */
-	rs485->delay_rts_before_send = min(rs485->delay_rts_before_send, 100U);
-	rs485->delay_rts_after_send = min(rs485->delay_rts_after_send, 100U);
+	uart_sanitize_rs485_mode(port);
 
 	return 0;
 }

drivers/tty/serial/serial_core.c

@@ -3271,5 +3271,32 @@ int uart_get_rs485_mode(struct uart_port *port)
 }
 EXPORT_SYMBOL_GPL(uart_get_rs485_mode);
 
+/**
+ * uart_sanitize_rs485_mode() - sanitize rs485 properties for given uart
+ * @port: uart device's target port
+ *
+ * Correct faulty rs485 properties after they're passed in from user space
+ * through a TIOCSRS485 ioctl() or retrieved from the device tree or ACPI.
+ */
+void uart_sanitize_rs485_mode(struct uart_port *port)
+{
+	struct serial_rs485 *rs485 = &port->rs485;
+	struct device *dev = port->dev;
+
+	/* assume active-high polarity if settings are nonsensical */
+	if (!!(rs485->flags & SER_RS485_RTS_ON_SEND) ==
+	    !!(rs485->flags & SER_RS485_RTS_AFTER_SEND)) {
+		rs485->flags |= SER_RS485_RTS_ON_SEND;
+		rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
+	}
+
+	/* clamp the delays to [0, 100ms] */
+	rs485->delay_rts_before_send = min(rs485->delay_rts_before_send, 100U);
+	rs485->delay_rts_after_send  = min(rs485->delay_rts_after_send, 100U);
+
+	memset(rs485->padding, 0, sizeof(rs485->padding));
+}
+EXPORT_SYMBOL_GPL(uart_sanitize_rs485_mode);
+
 MODULE_DESCRIPTION("Serial driver core");
 MODULE_LICENSE("GPL");

include/linux/serial_core.h

@@ -589,4 +589,5 @@ static inline int uart_handle_break(struct uart_port *port)
 					 !((cflag) & CLOCAL))
 
 int uart_get_rs485_mode(struct uart_port *port);
+void uart_sanitize_rs485_mode(struct uart_port *port);
 #endif /* LINUX_SERIAL_CORE_H */