diff options
Diffstat (limited to 'drivers/tty/serial/serial_core.c')
| -rw-r--r-- | drivers/tty/serial/serial_core.c | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 66a5e2faf57e..57840cf90388 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -3295,8 +3295,10 @@ EXPORT_SYMBOL(uart_remove_one_port); * This function implements the device tree binding described in * Documentation/devicetree/bindings/serial/rs485.txt. */ -void uart_get_rs485_mode(struct device *dev, struct serial_rs485 *rs485conf) +int uart_get_rs485_mode(struct uart_port *port) { + struct serial_rs485 *rs485conf = &port->rs485; + struct device *dev = port->dev; u32 rs485_delay[2]; int ret; @@ -3315,6 +3317,7 @@ void uart_get_rs485_mode(struct device *dev, struct serial_rs485 *rs485conf) * to get to a defined state with the following properties: */ rs485conf->flags &= ~(SER_RS485_RX_DURING_TX | SER_RS485_ENABLED | + SER_RS485_TERMINATE_BUS | SER_RS485_RTS_AFTER_SEND); rs485conf->flags |= SER_RS485_RTS_ON_SEND; @@ -3328,6 +3331,23 @@ void uart_get_rs485_mode(struct device *dev, struct serial_rs485 *rs485conf) rs485conf->flags &= ~SER_RS485_RTS_ON_SEND; rs485conf->flags |= SER_RS485_RTS_AFTER_SEND; } + + /* + * Disabling termination by default is the safe choice: Else if many + * bus participants enable it, no communication is possible at all. + * Works fine for short cables and users may enable for longer cables. + */ + port->rs485_term_gpio = devm_gpiod_get_optional(dev, "rs485-term", + GPIOD_OUT_LOW); + if (IS_ERR(port->rs485_term_gpio)) { + ret = PTR_ERR(port->rs485_term_gpio); + port->rs485_term_gpio = NULL; + if (ret != -EPROBE_DEFER) + dev_err(dev, "Cannot get rs485-term-gpios\n"); + return ret; + } + + return 0; } EXPORT_SYMBOL_GPL(uart_get_rs485_mode); |