linux-kernel - [PATCH v2 1/2] tty/serial: Add rx-tx-swap OF option to stm32-usart

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Message-Id: <20210227164157.30971-1-devik@eaxlabs.cz>
Date:   Sat, 27 Feb 2021 17:41:56 +0100
From:   Martin Devera <devik@...labs.cz>
To:     linux-kernel@...r.kernel.org
Cc:     Martin Devera <devik@...labs.cz>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Jiri Slaby <jirislaby@...nel.org>, Le Ray <erwan.leray@...com>,
        linux-serial@...r.kernel.org, devicetree@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH v2 1/2] tty/serial: Add rx-tx-swap OF option to stm32-usart

STM32 F7/H7 usarts supports RX & TX pin swapping.
Add option to turn it on.
Tested on STM32MP157.

Signed-off-by: Martin Devera <devik@...labs.cz>
---
 drivers/tty/serial/stm32-usart.c | 3 ++-
 drivers/tty/serial/stm32-usart.h | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index b3675cf25a69..3650c8798061 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -758,7 +758,7 @@ static void stm32_usart_set_termios(struct uart_port *port,
 	cr1 = USART_CR1_TE | USART_CR1_RE;
 	if (stm32_port->fifoen)
 		cr1 |= USART_CR1_FIFOEN;
-	cr2 = 0;
+	cr2 = stm32_port->swap ? USART_CR2_SWAP : 0;
 	cr3 = readl_relaxed(port->membase + ofs->cr3);
 	cr3 &= USART_CR3_TXFTIE | USART_CR3_RXFTCFG_MASK | USART_CR3_RXFTIE
 		| USART_CR3_TXFTCFG_MASK;
@@ -1078,6 +1078,7 @@ static struct stm32_port *stm32_usart_of_get_port(struct platform_device *pdev)
 	stm32_ports[id].hw_flow_control =
 		of_property_read_bool (np, "st,hw-flow-ctrl") /*deprecated*/ ||
 		of_property_read_bool (np, "uart-has-rtscts");
+	stm32_ports[id].swap = of_property_read_bool(np, "rx-tx-swap");
 	stm32_ports[id].port.line = id;
 	stm32_ports[id].cr1_irq = USART_CR1_RXNEIE;
 	stm32_ports[id].cr3_irq = 0;
diff --git a/drivers/tty/serial/stm32-usart.h b/drivers/tty/serial/stm32-usart.h
index cb4f327c46db..2f054e2dc0ab 100644
--- a/drivers/tty/serial/stm32-usart.h
+++ b/drivers/tty/serial/stm32-usart.h
@@ -271,6 +271,7 @@ struct stm32_port {
 	int last_res;
 	bool tx_dma_busy;	 /* dma tx busy               */
 	bool hw_flow_control;
+	bool swap;		 /* swap RX & TX pins */
 	bool fifoen;
 	int wakeirq;
 	int rdr_mask;		/* receive data register mask */
-- 
2.11.0