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[ Upstream commit 5963d97aa780619ffb66cf4886c0ca1175ccbd3e ] A hardware switch can set the rs485 transceiver into half or full duplex mode. Switching to the half-duplex mode requires the user to enable em485 on uart5 using ioctl, DE/RE are both connected to GPIO0_B5 which is the RTS signal for uart0. Implement GPIO0_B5 as rts-gpios with RTS_ON_SEND option enabled (default) so that driver mode gets enabled while sending (RTS high) and receiver mode gets enabled while not sending (RTS low). In full-duplex mode (em485 is disabled), DE is connected to GPIO0_B5 and RE is grounded (enabled). Since GPIO0_B5 is implemented as rts-gpios, the driver mode gets enabled whenever we want to send something and RE is not affected (always enabled) in this case by the state of RTS. Signed-off-by: Farouk Bouabid <farouk.bouabid@theobroma-systems.com> Link: https://lore.kernel.org/r/20240208-dev-rx-enable-v6-2-39e68e17a339@theobroma-systems.com Signed-off-by: Heiko Stuebner <heiko@sntech.de> Stable-dep-of: 5ae4dca718ea ("arm64: dts: rockchip: Disable DMA for uart5 on px30-ringneck") Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.