This patch series add the ability to control the RS485 feature RX_DURING_TX via a GPIO. Currently it is handled by the low level serial driver and it depends on the ability of the serial hardware. In case of that RX_DURING_TX is disabled the serial hardware must be capable to turn off the receiver during sending. The idea is to have an electrical circuit that connects/disconnects the Rx by using the RX_DURING_TX GPIO. On one hand by using this GPIO the use of RS485 RX_DURING_TX becomes independent of the capability of the serial hardware, and on the other hand possible software-caused switch-off and switch-on times of the receiver in case of RX_DURING_TX is disabled (default state) can also be avoided. The core patch adds a generic GPIO variable for the use of this RS485 feature controlled by a GPIO. The GPIO is defined by the devicetree property "rs485-rx-during-tx-gpios". The low-level implementation is done for the STM32 and the i.MX serial driver. Other platforms are not covered in this series, but can easily be added. I tested it with a DHCOM i.MX6DL and DHCOM STM32MP1 on a PicoITX board. In this series the devicetree bindings description is also included. Christoph Niedermaier (4): dt_bindings: rs485: Add binding for GPIO that controls Rx enable during Tx serial: core: Add option to control rs485 RX_DURING_TX by a GPIO serial: imx: Add support for rs485 RX_DURING_TX GPIO serial: stm32: Add support for rs485 RX_DURING_TX GPIO Documentation/devicetree/bindings/serial/rs485.yaml | 4 ++++ drivers/tty/serial/imx.c | 13 +++++++++++-- drivers/tty/serial/serial_core.c | 12 ++++++++++++ drivers/tty/serial/stm32-usart.c | 9 ++++++++- include/linux/serial_core.h | 1 + 5 files changed, 36 insertions(+), 3 deletions(-) -- 2.11.0