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serial: core: Add option to output RS485 RX_DURING_TX state via GPIO

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This patch provides a generic GPIO variable for outputting the state
of RS485 RX_DURING_TX. The GPIO is defined by the devicetree property
"rs485-rx-during-tx-gpios". To use it in a low level serial driver,
the evaluation of this variable must be implemented there accordingly.

Signed-off-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Link: https://lore.kernel.org/r/20221202104127.122761-2-cniedermaier@dh-electronics.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Christoph Niedermaier 2022-12-02 11:41:25 +01:00 committed by Greg Kroah-Hartman
parent 45c1d967a7
commit 163f080eb7
2 changed files with 13 additions and 0 deletions
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12
drivers/tty/serial/serial_core.c
View file

@ -3410,6 +3410,7 @@ int uart_get_rs485_mode(struct uart_port *port)
struct device *dev = port->dev;
u32 rs485_delay[2];
int ret;
int rx_during_tx_gpio_flag;
ret = device_property_read_u32_array(dev, "rs485-rts-delay",
rs485_delay, 2);
@ -3458,6 +3459,17 @@ int uart_get_rs485_mode(struct uart_port *port)
if (port->rs485_term_gpio)
port->rs485_supported.flags |= SER_RS485_TERMINATE_BUS;
rx_during_tx_gpio_flag = (rs485conf->flags & SER_RS485_RX_DURING_TX) ?
GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
port->rs485_rx_during_tx_gpio = devm_gpiod_get_optional(dev,
"rs485-rx-during-tx",
rx_during_tx_gpio_flag);
if (IS_ERR(port->rs485_rx_during_tx_gpio)) {
ret = PTR_ERR(port->rs485_rx_during_tx_gpio);
port->rs485_rx_during_tx_gpio = NULL;
return dev_err_probe(dev, ret, "Cannot get rs485-rx-during-tx-gpios\n");
}
return 0;
}
EXPORT_SYMBOL_GPL(uart_get_rs485_mode);

1
include/linux/serial_core.h
View file

@ -579,6 +579,7 @@ struct uart_port {
struct serial_rs485 rs485;
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 serial_iso7816 iso7816;
void *private_data; /* generic platform data pointer */
};