Re: [PATCH v3 2/2] tty/serial: Add rx-tx-swap OF option to stm32-usart

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On 3/2/21 6:44 PM, Fabrice Gasnier wrote:
On 3/2/21 2:15 PM, Martin Devera wrote:
STM32 F7/H7 usarts supports RX & TX pin swapping.
Add option to turn it on.
Tested on STM32MP157.

Signed-off-by: Martin Devera <devik@xxxxxxxxxx>
---
  drivers/tty/serial/stm32-usart.c | 11 ++++++++++-
  drivers/tty/serial/stm32-usart.h |  5 +++++
  2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index b3675cf25a69..d390f7da1441 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -644,6 +644,12 @@ static int stm32_usart_startup(struct uart_port *port)
  	if (ret)
  		return ret;
+ if (stm32_port->swap) {
+		val = readl_relaxed(port->membase + ofs->cr2);
+		val |= USART_CR2_SWAP;
+		writel_relaxed(val, port->membase + ofs->cr2);
+	}
+
  	/* RX FIFO Flush */
  	if (ofs->rqr != UNDEF_REG)
  		stm32_usart_set_bits(port, ofs->rqr, USART_RQR_RXFRQ);
@@ -758,7 +764,7 @@ 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;
@@ -1006,6 +1012,9 @@ static int stm32_usart_init_port(struct stm32_port *stm32port,
  			return stm32port->wakeirq ? : -ENODEV;
  	}
+ stm32port->swap = stm32port->info->cfg.has_swap &&
+		of_property_read_bool(pdev->dev.of_node, "rx-tx-swap");
+
  	stm32port->fifoen = stm32port->info->cfg.has_fifo;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
diff --git a/drivers/tty/serial/stm32-usart.h b/drivers/tty/serial/stm32-usart.h
index cb4f327c46db..bd18dd1c1bcd 100644
--- a/drivers/tty/serial/stm32-usart.h
+++ b/drivers/tty/serial/stm32-usart.h
@@ -25,6 +25,7 @@ struct stm32_usart_offsets {
  struct stm32_usart_config {
  	u8 uart_enable_bit; /* USART_CR1_UE */
  	bool has_7bits_data;
+	bool has_swap;
  	bool has_wakeup;
  	bool has_fifo;
  	int fifosize;
@@ -55,6 +56,7 @@ struct stm32_usart_info stm32f4_info = {
  	.cfg = {
  		.uart_enable_bit = 13,
  		.has_7bits_data = false,
+		.has_swap = false,
Hi Martin,

Only one minor comment from me here. No need to add a false (zero)
initialization in this struct. I'm not sure why this is the case for the
has_7bits_data here...

With that fixed, you can add my:
Acked-by: Fabrice Gasnier <fabrice.gasnier@xxxxxxxxxxx>

The has_7bits_data was what made me a bit unsure. Ok fixed now.
Thank you for your review.

Martin




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