[PATCH 2/2] dt-bindings: serial: Document WK2xxx SPI UART bindings

[zjzhao <zjzhao@edatec.cn>]

Add a DT binding for the WK2xxx SPI to UART bridge ICs (WK2124, WK2132,
WK2168, WK2202 and WK2204) from WKmic (Chengdu Weikai Microelectronics),
covering the compatible strings, SPI properties, the optional interrupt
line and the crystal clock frequency. Also register the wkmic vendor
prefix.

Signed-off-by: zjzhao <zjzhao@edatec.cn>
---
 .../bindings/serial/wkmic,wk2xxx.yaml         | 69 +++++++++++++++++++
 .../devicetree/bindings/vendor-prefixes.yaml  |  2 +
 2 files changed, 71 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/serial/wkmic,wk2xxx.yaml

diff --git a/Documentation/devicetree/bindings/serial/wkmic,wk2xxx.yaml b/Documentation/devicetree/bindings/serial/wkmic,wk2xxx.yaml
new file mode 100644
index 000000000000..0ef76957d73f
--- /dev/null
+++ b/Documentation/devicetree/bindings/serial/wkmic,wk2xxx.yaml
@@ -0,0 +1,69 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/serial/wkmic,wk2xxx.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: WKmic WK2xxx SPI to UART bridge
+
+maintainers:
+  - EDATEC Technology Co., Ltd. <zjzhao@edatec.cn>
+
+description:
+  The WK2xxx family (WK2124, WK2132, WK2168, WK2202 and WK2204) are SPI to
+  UART bridge ICs from WKmic (Chengdu Weikai Microelectronics). Each IC
+  exposes two or four full-duplex UART channels with 256-byte RX/TX FIFOs
+  through a single SPI slave interface and one interrupt line.
+
+properties:
+  compatible:
+    enum:
+      - wkmic,wk2124
+      - wkmic,wk2132
+      - wkmic,wk2168
+      - wkmic,wk2202
+      - wkmic,wk2204
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    description:
+      When missing, the device driver uses polling instead.
+    maxItems: 1
+
+  clock-frequency:
+    description:
+      Crystal or external clock frequency for the IC in Hz. The WK2xxx has
+      no internal clock, so this must match the connected crystal. Defaults
+      to 11059200 Hz when the property is absent.
+    minimum: 1
+    maximum: 30000000
+
+required:
+  - compatible
+  - reg
+
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+  - $ref: /schemas/serial/serial.yaml#
+  - $ref: /schemas/serial/rs485.yaml#
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        serial@0 {
+            compatible = "wkmic,wk2132";
+            reg = <0>;
+            spi-max-frequency = <10000000>;
+            clock-frequency = <11059200>;
+            interrupt-parent = <&gpio>;
+            interrupts = <24 IRQ_TYPE_LEVEL_LOW>;
+        };
+    };
\ No newline at end of file
diff --git a/Documentation/devicetree/bindings/vendor-prefixes.yaml b/Documentation/devicetree/bindings/vendor-prefixes.yaml
index ba2002969373..654fc8525559 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.yaml
+++ b/Documentation/devicetree/bindings/vendor-prefixes.yaml
@@ -1907,6 +1907,8 @@ patternProperties:
     description: Wireless Tag (qiming yunduan)
   "^wits,.*":
     description: Shenzhen Merrii Technology Co., Ltd. (WITS)
+  "^wkmic,.*":
+    description: Chengdu Weikai Microelectronics Co., Ltd.
   "^wlf,.*":
     description: Wolfson Microelectronics
   "^wm,.*":
-- 
2.43.0