dt-bindings: gpio: add bindings for microchip mpfs gpio

Add device tree bindings for the gpio controller on
the Microchip PolarFire SoC.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Acked-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Documentation/devicetree/bindings/gpio/microchip,mpfs-gpio.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gpio/microchip,mpfs-gpio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microchip MPFS GPIO Controller Device Tree Bindings
+
+maintainers:
+  - Conor Dooley <conor.dooley@microchip.com>
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - microchip,mpfs-gpio
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    description:
+      Interrupt mapping, one per GPIO. Maximum 32 GPIOs.
+    minItems: 1
+    maxItems: 32
+
+  interrupt-controller: true
+
+  clocks:
+    maxItems: 1
+
+  "#gpio-cells":
+    const: 2
+
+  "#interrupt-cells":
+    const: 1
+
+  ngpios:
+    description:
+      The number of GPIOs available.
+    minimum: 1
+    maximum: 32
+    default: 32
+
+  gpio-controller: true
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - "#interrupt-cells"
+  - interrupt-controller
+  - "#gpio-cells"
+  - gpio-controller
+  - clocks
+
+additionalProperties: false
+
+examples:
+  - |
+    gpio@20122000 {
+        compatible = "microchip,mpfs-gpio";
+        reg = <0x20122000 0x1000>;
+        clocks = <&clkcfg 25>;
+        interrupt-parent = <&plic>;
+        gpio-controller;
+        #gpio-cells = <2>;
+        interrupt-controller;
+        #interrupt-cells = <1>;
+        interrupts = <53>, <53>, <53>, <53>,
+                     <53>, <53>, <53>, <53>,
+                     <53>, <53>, <53>, <53>,
+                     <53>, <53>, <53>, <53>,
+                     <53>, <53>, <53>, <53>,
+                     <53>, <53>, <53>, <53>,
+                     <53>, <53>, <53>, <53>,
+                     <53>, <53>, <53>, <53>;
+    };
+...