Hi Rob,

From: Rob Herring <robh@kernel.org>
Sent: Friday, September 17, 2021 4:19 AM

On Thu, Sep 16, 2021 at 05:25:13PM +0800, Chia-Wei Wang wrote:

quoted

Add dt-bindings for Aspeed UART routing controller.

Signed-off-by: Oskar Senft <redacted>
Signed-off-by: Chia-Wei Wang <redacted>
---
 .../devicetree/bindings/mfd/aspeed-lpc.yaml   |  4 ++
 .../bindings/soc/aspeed/uart-routing.yaml     | 70

+++++++++++++++++++

quoted

 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@google.com>
+  - Chia-Wei Wang <chiawei_wang@aspeedtech.com>
+
+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