Hi,
On 20.11.23 16:10, Rasmus Villemoes wrote:
> Add code for handling a rs485-mux-gpio specified in device tree.
>
> Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/tty/serial/serial_core.c | 35 ++++++++++++++++++++++++++++++--
> include/linux/serial_core.h | 1 +
> 2 files changed, 34 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index f1348a509552..410b17ea7444 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -1402,14 +1402,20 @@ static void uart_set_rs485_termination(struct uart_port *port,
> !!(rs485->flags & SER_RS485_TERMINATE_BUS));
> }
>
> +static void uart_set_rs485_mux(struct uart_port *port, const struct serial_rs485 *rs485)
> +{
> + gpiod_set_value_cansleep(port->rs485_mux_gpio,
> + !!(rs485->flags & SER_RS485_ENABLED));
> +}
> +
> static int uart_rs485_config(struct uart_port *port)
> {
> struct serial_rs485 *rs485 = &port->rs485;
> unsigned long flags;
> - int ret;
> + int ret = 0;
>
> if (!(rs485->flags & SER_RS485_ENABLED))
> - return 0;
> + goto out;
>
> uart_sanitize_serial_rs485(port, rs485);
> uart_set_rs485_termination(port, rs485);
> @@ -1420,6 +1426,9 @@ static int uart_rs485_config(struct uart_port *port)
> if (ret)
> memset(rs485, 0, sizeof(*rs485));
>
> +out:
> + uart_set_rs485_mux(port, rs485);
> +
> return ret;
> }
>
> @@ -1457,6 +1466,14 @@ static int uart_set_rs485_config(struct tty_struct *tty, struct uart_port *port,
> return ret;
> uart_sanitize_serial_rs485(port, &rs485);
> uart_set_rs485_termination(port, &rs485);
> + /*
> + * To avoid glitches on the transmit enable pin, the mux must
> + * be set before calling the driver's ->rs485_config when
> + * disabling rs485 mode, but after when enabling rs485
> + * mode.
> + */
> + if (!(rs485.flags & SER_RS485_ENABLED))
> + uart_set_rs485_mux(port, &rs485);
>
> uart_port_lock_irqsave(port, &flags);
> ret = port->rs485_config(port, &tty->termios, &rs485);
> @@ -1468,6 +1485,13 @@ static int uart_set_rs485_config(struct tty_struct *tty, struct uart_port *port,
> port->ops->set_mctrl(port, port->mctrl);
> }
> uart_port_unlock_irqrestore(port, flags);
> +
> + /*
> + * The ->rs485_config might have failed. Regardless, set the
> + * mux according to the port's effective rs485 config.
> + */
> + uart_set_rs485_mux(port, &port->rs485);
> +
> if (ret)
> return ret;
>
> @@ -3621,6 +3645,13 @@ int uart_get_rs485_mode(struct uart_port *port)
> return dev_err_probe(dev, PTR_ERR(desc), "Cannot get rs485-rx-during-tx-gpios\n");
> port->rs485_rx_during_tx_gpio = desc;
>
> + dflags = (rs485conf->flags & SER_RS485_ENABLED) ? GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
> + desc = devm_gpiod_get_optional(dev, "rs485-mux", dflags);
> + if (IS_ERR(desc))
> + return dev_err_probe(dev, PTR_ERR(port->rs485_mux_gpio),
> + "Cannot get rs485-mux-gpios\n");
> + port->rs485_mux_gpio = desc;
> +
> return 0;
> }
> EXPORT_SYMBOL_GPL(uart_get_rs485_mode);
> diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
> index 89f7b6c63598..943818209c49 100644
> --- a/include/linux/serial_core.h
> +++ b/include/linux/serial_core.h
> @@ -584,6 +584,7 @@ struct uart_port {
> struct serial_rs485 rs485_supported; /* Supported mask for serial_rs485 */
> struct gpio_desc *rs485_term_gpio; /* enable RS485 bus termination */
> struct gpio_desc *rs485_rx_during_tx_gpio; /* Output GPIO that sets the state of RS485 RX during TX */
> + struct gpio_desc *rs485_mux_gpio; /* gpio for selecting RS485 mode */
> struct serial_iso7816 iso7816;
> void *private_data; /* generic platform data pointer */
> };
FWIW
Reviewed-by: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx>
Regards,
Lino
