dt-bindings: gpio: brcm: Add bindings for xgs-iproc

This GPIO controller is present on a number of Broadcom switch ASICs
with integrated SoCs. It is similar to the nsp-gpio and iproc-gpio
blocks but different enough to require a separate driver.
Signed-off-by: NChris Packham <chris.packham@alliedtelesis.co.nz>
Reviewed-by: NRob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20191028200555.27524-1-chris.packham@alliedtelesis.co.nzAcked-by: NScott Branden <scott.branden@broadcom.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/gpio/brcm,xgs-iproc-gpio.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gpio/brcm,xgs-iproc-gpio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Broadcom XGS iProc GPIO controller
+
+maintainers:
+  - Chris Packham <chris.packham@alliedtelesis.co.nz>
+
+description: |
+  This controller is the Chip Common A GPIO present on a number of Broadcom
+  switch ASICs with integrated SoCs.
+
+properties:
+  compatible:
+    const: brcm,iproc-gpio-cca
+
+  reg:
+    items:
+      - description: the I/O address containing the GPIO controller
+                     registers.
+      - description: the I/O address containing the Chip Common A interrupt
+                     registers.
+
+  gpio-controller: true
+
+  '#gpio-cells':
+      const: 2
+
+  ngpios:
+    minimum: 0
+    maximum: 32
+
+  interrupt-controller: true
+
+  '#interrupt-cells':
+    const: 2
+
+  interrupts:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - "#gpio-cells"
+  - gpio-controller
+
+dependencies:
+  interrupt-controller: [ interrupts ]
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    gpio@18000060 {
+        compatible = "brcm,iproc-gpio-cca";
+        #gpio-cells = <2>;
+        reg = <0x18000060 0x50>,
+              <0x18000000 0x50>;
+        ngpios = <12>;
+        gpio-controller;
+        interrupt-controller;
+        #interrupt-cells = <2>;
+        interrupts = <GIC_SPI 91 IRQ_TYPE_LEVEL_HIGH>;
+    };
+
+
+...