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(-)
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2.11.0
