hw_random: ixp4xx: Add DT bindings

This adds device tree bindings for the simple random number
generator found in the IXP46x SoCs.

Cc: Deepak Saxena <dsaxena@plexity.net>
Cc: devicetree@vger.kernel.org
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/rng/intel,ixp46x-rng.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/rng/intel,ixp46x-rng.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Intel IXP46x RNG bindings
+
+description: |
+  The Intel IXP46x has a random number generator at a fixed physical
+  location in memory. Each read is guaranteed to provide a unique
+  32 bit random number.
+
+maintainers:
+  - Linus Walleij <linus.walleij@linaro.org>
+
+properties:
+  compatible:
+    const: intel,ixp46x-rng
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    rng@70002100 {
+      compatible = "intel,ixp46x-rng";
+      reg = <0x70002100 4>;
+    };
+

MAINTAINERS

@@ -9248,6 +9248,7 @@ F:	include/linux/soc/ixp4xx/qmgr.h
 INTEL IXP4XX RANDOM NUMBER GENERATOR SUPPORT
 M:	Deepak Saxena <dsaxena@plexity.net>
 S:	Maintained
+F:	Documentation/devicetree/bindings/display/intel,ixp46x-rng.yaml
 F:	drivers/char/hw_random/ixp4xx-rng.c
 
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