serial: stm32: Factor out GPIO RTS toggling into separate function

[ Upstream commit 3bcea52 ]

Pull out the GPIO RTS enable and disable handling into separate function.
Limit the scope of GPIO RTS toggling only to GPIO emulated RS485 too.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: Erwan Le Ray <erwan.leray@foss.st.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jean Philippe Romain <jean-philippe.romain@foss.st.com>
Cc: Valentin Caron <valentin.caron@foss.st.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-stm32@st-md-mailman.stormreply.com
To: linux-serial@vger.kernel.org
Link: https://lore.kernel.org/r/20220430162845.244655-1-marex@denx.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/tty/serial/stm32-usart.c

@@ -325,6 +325,42 @@ static void stm32_usart_tx_interrupt_disable(struct uart_port *port)
 		stm32_usart_clr_bits(port, ofs->cr1, USART_CR1_TXEIE);
 }
 
+static void stm32_usart_rs485_rts_enable(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct serial_rs485 *rs485conf = &port->rs485;
+
+	if (stm32_port->hw_flow_control ||
+	    !(rs485conf->flags & SER_RS485_ENABLED))
+		return;
+
+	if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
+		mctrl_gpio_set(stm32_port->gpios,
+			       stm32_port->port.mctrl | TIOCM_RTS);
+	} else {
+		mctrl_gpio_set(stm32_port->gpios,
+			       stm32_port->port.mctrl & ~TIOCM_RTS);
+	}
+}
+
+static void stm32_usart_rs485_rts_disable(struct uart_port *port)
+{
+	struct stm32_port *stm32_port = to_stm32_port(port);
+	struct serial_rs485 *rs485conf = &port->rs485;
+
+	if (stm32_port->hw_flow_control ||
+	    !(rs485conf->flags & SER_RS485_ENABLED))
+		return;
+
+	if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
+		mctrl_gpio_set(stm32_port->gpios,
+			       stm32_port->port.mctrl & ~TIOCM_RTS);
+	} else {
+		mctrl_gpio_set(stm32_port->gpios,
+			       stm32_port->port.mctrl | TIOCM_RTS);
+	}
+}
+
 static void stm32_usart_transmit_chars_pio(struct uart_port *port)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
@@ -566,41 +602,20 @@ static void stm32_usart_disable_ms(struct uart_port *port)
 /* Transmit stop */
 static void stm32_usart_stop_tx(struct uart_port *port)
 {
-	struct stm32_port *stm32_port = to_stm32_port(port);
-	struct serial_rs485 *rs485conf = &port->rs485;
-
 	stm32_usart_tx_interrupt_disable(port);
 
-	if (rs485conf->flags & SER_RS485_ENABLED) {
-		if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
-			mctrl_gpio_set(stm32_port->gpios,
-					stm32_port->port.mctrl & ~TIOCM_RTS);
-		} else {
-			mctrl_gpio_set(stm32_port->gpios,
-					stm32_port->port.mctrl | TIOCM_RTS);
-		}
-	}
+	stm32_usart_rs485_rts_disable(port);
 }
 
 /* There are probably characters waiting to be transmitted. */
 static void stm32_usart_start_tx(struct uart_port *port)
 {
-	struct stm32_port *stm32_port = to_stm32_port(port);
-	struct serial_rs485 *rs485conf = &port->rs485;
 	struct circ_buf *xmit = &port->state->xmit;
 
 	if (uart_circ_empty(xmit) && !port->x_char)
 		return;
 
-	if (rs485conf->flags & SER_RS485_ENABLED) {
-		if (rs485conf->flags & SER_RS485_RTS_ON_SEND) {
-			mctrl_gpio_set(stm32_port->gpios,
-					stm32_port->port.mctrl | TIOCM_RTS);
-		} else {
-			mctrl_gpio_set(stm32_port->gpios,
-					stm32_port->port.mctrl & ~TIOCM_RTS);
-		}
-	}
+	stm32_usart_rs485_rts_enable(port);
 
 	stm32_usart_transmit_chars(port);
 }