dt-bindings: mtd: Describe Macronix NAND ECC engine

Describe Macronix NAND ECC engine. This engine may be used as an
external engine or can be pipelined with either a raw NAND controller or
a SPI controller. Both hardware designs with a SPI controller are shown
in the examples.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/linux-mtd/20211216111654.238086-11-miquel.raynal@bootlin.com

Documentation/devicetree/bindings/mtd/mxicy,nand-ecc-engine.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mtd/mxicy,nand-ecc-engine.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Macronix NAND ECC engine device tree bindings
+
+maintainers:
+  - Miquel Raynal <miquel.raynal@bootlin.com>
+
+properties:
+  compatible:
+    const: mxicy,nand-ecc-engine-rev3
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    /* External configuration */
+    spi_controller0: spi@43c30000 {
+        compatible = "mxicy,mx25f0a-spi";
+        reg = <0x43c30000 0x10000>, <0xa0000000 0x4000000>;
+        reg-names = "regs", "dirmap";
+        clocks = <&clkwizard 0>, <&clkwizard 1>, <&clkc 15>;
+        clock-names = "send_clk", "send_dly_clk", "ps_clk";
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        flash@0 {
+            compatible = "spi-nand";
+            reg = <0>;
+            nand-ecc-engine = <&ecc_engine0>;
+        };
+    };
+
+    ecc_engine0: ecc@43c40000 {
+        compatible = "mxicy,nand-ecc-engine-rev3";
+        reg = <0x43c40000 0x10000>;
+    };
+
+  - |
+    /* Pipelined configuration */
+    spi_controller1: spi@43c30000 {
+        compatible = "mxicy,mx25f0a-spi";
+        reg = <0x43c30000 0x10000>, <0xa0000000 0x4000000>;
+        reg-names = "regs", "dirmap";
+        clocks = <&clkwizard 0>, <&clkwizard 1>, <&clkc 15>;
+        clock-names = "send_clk", "send_dly_clk", "ps_clk";
+        #address-cells = <1>;
+        #size-cells = <0>;
+        nand-ecc-engine = <&ecc_engine1>;
+
+        flash@0 {
+            compatible = "spi-nand";
+            reg = <0>;
+            nand-ecc-engine = <&spi_controller1>;
+        };
+    };
+
+    ecc_engine1: ecc@43c40000 {
+        compatible = "mxicy,nand-ecc-engine-rev3";
+        reg = <0x43c40000 0x10000>;
+    };