dt-bindings: reserved-memory: Open Profile for DICE

Add DeviceTree bindings for Open Profile for DICE, an open protocol for
measured boot. Firmware uses DICE to measure the hardware/software
combination and generates Compound Device Identifier (CDI) certificates.
These are stored in memory and the buffer is described in the DT as
a reserved memory region compatible with 'google,open-dice'.

'no-map' is required to ensure the memory region is never treated by
the kernel as system memory.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: David Brazdil <dbrazdil@google.com>
Link: https://lore.kernel.org/r/20220126231237.529308-2-dbrazdil@google.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/reserved-memory/google,open-dice.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/reserved-memory/google,open-dice.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Open Profile for DICE Device Tree Bindings
+
+description: |
+  This binding represents a reserved memory region containing data
+  generated by the Open Profile for DICE protocol.
+
+  See https://pigweed.googlesource.com/open-dice/
+
+maintainers:
+  - David Brazdil <dbrazdil@google.com>
+
+allOf:
+  - $ref: "reserved-memory.yaml"
+
+properties:
+  compatible:
+    const: google,open-dice
+
+  reg:
+    description: page-aligned region of memory containing DICE data
+
+required:
+  - compatible
+  - reg
+  - no-map
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    reserved-memory {
+        #address-cells = <2>;
+        #size-cells = <1>;
+
+        dice: dice@12340000 {
+            compatible = "google,open-dice";
+            reg = <0x00 0x12340000 0x2000>;
+            no-map;
+        };
+    };