Hi Rob, > From: Rob Herring <robh@xxxxxxxxxx> > Sent: Friday, September 17, 2021 4:19 AM > > On Thu, Sep 16, 2021 at 05:25:13PM +0800, Chia-Wei Wang wrote: > > Add dt-bindings for Aspeed UART routing controller. > > > > Signed-off-by: Oskar Senft <osk@xxxxxxxxxx> > > Signed-off-by: Chia-Wei Wang <chiawei_wang@xxxxxxxxxxxxxx> > > --- > > .../devicetree/bindings/mfd/aspeed-lpc.yaml | 4 ++ > > .../bindings/soc/aspeed/uart-routing.yaml | 70 > +++++++++++++++++++ > > 2 files changed, 74 insertions(+) > > create mode 100644 > > Documentation/devicetree/bindings/soc/aspeed/uart-routing.yaml > > > > diff --git a/Documentation/devicetree/bindings/mfd/aspeed-lpc.yaml > > b/Documentation/devicetree/bindings/mfd/aspeed-lpc.yaml > > index 54f080df5e2f..697331d840a0 100644 > > --- a/Documentation/devicetree/bindings/mfd/aspeed-lpc.yaml > > +++ b/Documentation/devicetree/bindings/mfd/aspeed-lpc.yaml > > @@ -142,6 +142,10 @@ patternProperties: > > - interrupts > > - snoop-ports > > > > + "^uart-routing@[0-9a-f]+$": > > + $ref: /schemas/soc/aspeed/uart-routing.yaml# > > + description: The UART routing control under LPC register space > > + > > required: > > - compatible > > - reg > > diff --git > > a/Documentation/devicetree/bindings/soc/aspeed/uart-routing.yaml > > b/Documentation/devicetree/bindings/soc/aspeed/uart-routing.yaml > > new file mode 100644 > > index 000000000000..534b2a9340ce > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/soc/aspeed/uart-routing.yaml > > @@ -0,0 +1,70 @@ > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) # # > > +Copyright (c) 2018 Google LLC # # Copyright (c) 2021 Aspeed > > +Technology Inc. > > +%YAML 1.2 > > +--- > > +$id: "http://devicetree.org/schemas/soc/aspeed/uart-routing.yaml#"; > > +$schema: "http://devicetree.org/meta-schemas/core.yaml#"; > > + > > +title: Aspeed UART Routing Controller > > + > > +maintainers: > > + - Oskar Senft <osk@xxxxxxxxxx> > > + - Chia-Wei Wang <chiawei_wang@xxxxxxxxxxxxxx> > > + > > +description: > > + The Aspeed UART routing control allow to dynamically route the > > +inputs for > > + the built-in UARTS and physical serial I/O ports. > > + > > + This allows, for example, to connect the output of UART to another UART. > > + This can be used to enable Host <-> BMC communication via UARTs, > > + e.g. to allow access to the Host's serial console. > > + > > + This driver is for the BMC side. The sysfs files allow the BMC > > + userspace which owns the system configuration policy, to configure > > + how UARTs and physical serial I/O ports are routed. > > + > > + Two types of files, uart* and io*, are presented in sysfs. The > > + uart* configures the input signal of a UART controller whereas io* > > + configures that of a physical serial port. > > + > > + When read, each file shows the list of available options with > > + currently selected option marked by brackets "[]". The list of > > + available options depends on the selected file. > > + > > + e.g. > > + cat > > + /sys/bus/platform/drivers/aspeed-uart-routing/*.uart_routing/uart1 > > + [io1] io2 io3 io4 uart2 uart3 uart4 io6 > > + > > + In this case, UART1 gets its input from IO1 (physical serial port 1). > > This is about documenting the hardware, not an OS driver. > > sysfs files have their own documentation. > Understood. I will remove this sysfs description from bindings in the next revision. Thanks. Chiawei
