dt-bindings: gpio: Add renesas,em-gio bindings

Document Device Tree bindings for the Renesas EMMA Mobile General
Purpose I/O Interface.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/r/20200519081157.29095-1-geert+renesas@glider.beSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/gpio/renesas,em-gio.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gpio/renesas,em-gio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Renesas EMMA Mobile General Purpose I/O Interface
+
+maintainers:
+  - Magnus Damm <magnus.damm@gmail.com>
+
+properties:
+  compatible:
+    const: renesas,em-gio
+
+  reg:
+    items:
+      - description: First set of contiguous registers
+      - description: Second set of contiguous registers
+
+  interrupts:
+    items:
+      - description: Interrupt for the first set of 16 GPIO ports
+      - description: Interrupt for the second set of 16 GPIO ports
+
+  gpio-controller: true
+
+  '#gpio-cells':
+    const: 2
+
+  gpio-ranges:
+    maxItems: 1
+
+  ngpios:
+    minimum: 1
+    maximum: 32
+
+  interrupt-controller: true
+
+  '#interrupt-cells':
+    const: 2
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - gpio-controller
+  - '#gpio-cells'
+  - gpio-ranges
+  - ngpios
+  - interrupt-controller
+  - '#interrupt-cells'
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    gpio0: gpio@e0050000 {
+            compatible = "renesas,em-gio";
+            reg = <0xe0050000 0x2c>, <0xe0050040 0x20>;
+            interrupts = <GIC_SPI 67 IRQ_TYPE_LEVEL_HIGH>,
+                         <GIC_SPI 68 IRQ_TYPE_LEVEL_HIGH>;
+            gpio-controller;
+            #gpio-cells = <2>;
+            gpio-ranges = <&pfc 0 0 32>;
+            ngpios = <32>;
+            interrupt-controller;
+            #interrupt-cells = <2>;
+    };