dt-bindings: add BCM6358 GPIO sysctl binding documentation

Add binding documentation for the GPIO sysctl found in BCM6358 SoCs.
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210324081923.20379-10-noltari@gmail.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/mfd/brcm,bcm6358-gpio-sysctl.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mfd/brcm,bcm6358-gpio-sysctl.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Broadcom BCM6358 GPIO System Controller Device Tree Bindings
+
+maintainers:
+  - Álvaro Fernández Rojas <noltari@gmail.com>
+  - Jonas Gorski <jonas.gorski@gmail.com>
+
+description:
+  Broadcom BCM6358 SoC GPIO system controller which provides a register map
+  for controlling the GPIO and pins of the SoC.
+
+properties:
+  "#address-cells": true
+
+  "#size-cells": true
+
+  compatible:
+    items:
+      - const: brcm,bcm6358-gpio-sysctl
+      - const: syscon
+      - const: simple-mfd
+
+  ranges:
+    maxItems: 1
+
+  reg:
+    maxItems: 1
+
+patternProperties:
+  "^gpio@[0-9a-f]+$":
+    # Child node
+    type: object
+    $ref: "../gpio/brcm,bcm6345-gpio.yaml"
+    description:
+      GPIO controller for the SoC GPIOs. This child node definition
+      should follow the bindings specified in
+      Documentation/devicetree/bindings/gpio/brcm,bcm6345-gpio.yaml.
+
+  "^pinctrl@[0-9a-f]+$":
+    # Child node
+    type: object
+    $ref: "../pinctrl/brcm,bcm6358-pinctrl.yaml"
+    description:
+      Pin controller for the SoC pins. This child node definition
+      should follow the bindings specified in
+      Documentation/devicetree/bindings/pinctrl/brcm,bcm6358-pinctrl.yaml.
+
+required:
+  - "#address-cells"
+  - compatible
+  - ranges
+  - reg
+  - "#size-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    syscon@fffe0080 {
+      #address-cells = <1>;
+      #size-cells = <1>;
+      compatible = "brcm,bcm6358-gpio-sysctl", "syscon", "simple-mfd";
+      reg = <0xfffe0080 0x80>;
+      ranges = <0 0xfffe0080 0x80>;
+
+      gpio@0 {
+        compatible = "brcm,bcm6358-gpio";
+        reg-names = "dirout", "dat";
+        reg = <0x0 0x8>, <0x8 0x8>;
+
+        gpio-controller;
+        gpio-ranges = <&pinctrl 0 0 40>;
+        #gpio-cells = <2>;
+      };
+
+      pinctrl: pinctrl@18 {
+        compatible = "brcm,bcm6358-pinctrl";
+        reg = <0x18 0x4>;
+
+        pinctrl_ebi_cs: ebi_cs-pins {
+          function = "ebi_cs";
+          groups = "ebi_cs_grp";
+        };
+
+        pinctrl_uart1: uart1-pins {
+          function = "uart1";
+          groups = "uart1_grp";
+        };
+
+        pinctrl_serial_led: serial_led-pins {
+          function = "serial_led";
+          groups = "serial_led_grp";
+        };
+
+        pinctrl_legacy_led: legacy_led-pins {
+          function = "legacy_led";
+          groups = "legacy_led_grp";
+        };
+
+        pinctrl_led: led-pins {
+          function = "led";
+          groups = "led_grp";
+        };
+
+        pinctrl_spi_cs_23: spi_cs-pins {
+          function = "spi_cs";
+          groups = "spi_cs_grp";
+        };
+
+        pinctrl_utopia: utopia-pins {
+          function = "utopia";
+          groups = "utopia_grp";
+        };
+
+        pinctrl_pwm_syn_clk: pwm_syn_clk-pins {
+          function = "pwm_syn_clk";
+          groups = "pwm_syn_clk_grp";
+        };
+
+        pinctrl_sys_irq: sys_irq-pins {
+          function = "sys_irq";
+          groups = "sys_irq_grp";
+        };
+      };
+    };