Add the DT binding for the Apple Mac System Management Controller GPIOs.

Signed-off-by: Russell King (Oracle) <redacted>
---
 .../devicetree/bindings/gpio/gpio-macsmc.yaml | 28 +++++++++++++++++++
 .../devicetree/bindings/mfd/apple,smc.yaml    |  4 +++
 2 files changed, 32 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/gpio/gpio-macsmc.yaml

diff --git a/Documentation/devicetree/bindings/gpio/gpio-macsmc.yaml b/Documentation/devicetree/bindings/gpio/gpio-macsmc.yaml
new file mode 100644
index 000000000000..ee620fe50ca8
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/gpio-macsmc.yaml

@@ -0,0 +1,28 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gpio/gpio-macsmc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Apple Mac System Management Controller GPIO
+
+maintainers:
+  - Hector Martin <marcan@marcan.st>
+
+description:
+  This describes the binding for the Apple Mac System Management Controller
+  GPIO block.
+
+properties:
+  gpio-controller: true
+  '#gpio-cells':
+    const: 2
+
+additionalProperties: false
+
+examples:
+  - |
+    smc_gpio: gpio {
+      gpio-controller;
+      #gpio-cells = <2>;
+    };

diff --git a/Documentation/devicetree/bindings/mfd/apple,smc.yaml b/Documentation/devicetree/bindings/mfd/apple,smc.yaml
index 168f237c2962..47e3cd58bf19 100644
--- a/Documentation/devicetree/bindings/mfd/apple,smc.yaml
+++ b/Documentation/devicetree/bindings/mfd/apple,smc.yaml

@@ -37,6 +37,10 @@ title: Apple Mac System Management Controller
     description:
       A phandle to the mailbox channel
 
+patternProperties:
+  gpio: