[PATCH V3 4/4] serial: stm32: Add support for rs485 RX_DURING_TX output GPIO

[Ilpo Järvinen]

On Thu, 1 Dec 2022, Christoph Niedermaier wrote:

> If a RX_DURING_TX GPIO is defined by the DT property "rs485-rx-during-tx-gpios"
> this patch switches this GPIO accordingly to the RS485 flag RX_DURING_TX in user
> space. Controlled by this GPIO, now the hardware is responsible for connecting
> or disconnecting RX during TX.
> 
> Signed-off-by: Christoph Niedermaier <cniedermaier at dh-electronics.com>
> ---
> Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> Cc: Jiri Slaby <jirislaby at kernel.org>
> Cc: Maxime Coquelin <mcoquelin.stm32 at gmail.com>
> Cc: Alexandre Torgue <alexandre.torgue at foss.st.com>
> Cc: Alexander Dahl <ada at thorsis.com>
> Cc: Marek Vasut <marex at denx.de>
> Cc: kernel at dh-electronics.com
> Cc: linux-stm32 at st-md-mailman.stormreply.com
> To: linux-serial at vger.kernel.org
> To: linux-arm-kernel at lists.infradead.org
> ---
> V2: - Rework of the commit message
> V3: - No changes
> ---
>  drivers/tty/serial/stm32-usart.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
> index a1490033aa16..0f2cca9054ba 100644
> --- a/drivers/tty/serial/stm32-usart.c
> +++ b/drivers/tty/serial/stm32-usart.c
> @@ -226,7 +226,14 @@ static int stm32_usart_config_rs485(struct uart_port *port, struct ktermios *ter
>  
>  	stm32_usart_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
>  
> -	rs485conf->flags |= SER_RS485_RX_DURING_TX;
> +	if (port->rs485_rx_during_tx_gpio) {
> +		if (rs485conf->flags & SER_RS485_RX_DURING_TX)
> +			gpiod_set_value_cansleep(port->rs485_rx_during_tx_gpio, 1);
> +		else
> +			gpiod_set_value_cansleep(port->rs485_rx_during_tx_gpio, 0);

gpiod_set_value_cansleep(port->rs485_rx_during_tx_gpio,
			 !!(rs485conf->flags & SER_RS485_RX_DURING_TX));

And the same comment also for the other patch.

-- 
 i.