[PATCH v3 1/3] dt-bindings: aspeed: Add UART routing controller

[Chia-Wei Wang <chiawei_wang@aspeedtech.com>]

Add dt-bindings for Aspeed UART routing controller.

Signed-off-by: Oskar Senft <osk@google.com>
Signed-off-by: Chia-Wei Wang <chiawei_wang@aspeedtech.com>
---
 .../bindings/soc/aspeed/uart-routing.yaml     | 70 +++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/soc/aspeed/uart-routing.yaml

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..e7071f1abc03
--- /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).
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - aspeed,ast2400-uart-routing
+          - aspeed,ast2500-uart-routing
+          - aspeed,ast2600-uart-routing
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+
+additionalProperties: false
+
+examples:
+  - |
+    lpc: lpc@1e789000 {
+        compatible = "aspeed,ast2600-lpc-v2", "simple-mfd", "syscon";
+        reg = <0x1e789000 0x1000>;
+
+        #address-cells = <1>;
+        #size-cells = <1>;
+        ranges = <0x0 0x1e789000 0x1000>;
+
+        uart_routing: espi-routing@98 {
+            compatible = "aspeed,ast2600-uart-routing";
+            reg = <0x98 0x8>;
+        };
+    };
-- 
2.17.1