dt-bindings: mtd: renesas: Describe Renesas R-Car Gen3 & RZ/N1 NAND controller

Add a Yaml description for this Renesas NAND controller.

As this controller is embedded on different SoC families, provide:
* a family-specific "r-car-gen3" compatible and a more specific
  "r8a77951" one
* a family-specific "rzn1" compatible and a more specific "r9a06g032"
  one

More compatibles can be added later if new SoCs with this controller
must be supported.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/linux-mtd/20211217142033.353599-2-miquel.raynal@bootlin.com

Documentation/devicetree/bindings/mtd/renesas-nandc.yaml

@@ -0,0 +1,61 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mtd/renesas-nandc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Renesas R-Car Gen3 & RZ/N1x NAND flash controller device tree bindings
+
+maintainers:
+  - Miquel Raynal <miquel.raynal@bootlin.com>
+
+allOf:
+  - $ref: "nand-controller.yaml"
+
+properties:
+  compatible:
+    oneOf:
+      - items:
+          - enum:
+              - renesas,r9a06g032-nandc
+          - const: renesas,rzn1-nandc
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: APB host controller clock
+      - description: External NAND bus clock
+
+  clock-names:
+    items:
+      - const: hclk
+      - const: eclk
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - clock-names
+  - interrupts
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/clock/r9a06g032-sysctrl.h>
+
+    nand-controller@40102000 {
+        compatible = "renesas,r9a06g032-nandc", "renesas,rzn1-nandc";
+        reg = <0x40102000 0x2000>;
+        interrupts = <GIC_SPI 58 IRQ_TYPE_LEVEL_HIGH>;
+        clocks = <&sysctrl R9A06G032_HCLK_NAND>, <&sysctrl R9A06G032_CLK_NAND>;
+        clock-names = "hclk", "eclk";
+        #address-cells = <1>;
+        #size-cells = <0>;
+    };