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

Signed-off-by: Martin Devera <de...@eaxlabs.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

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