dt-bindings: mtd: nand-chip: Create a NAND chip description

Move the NAND chip description out of the NAND controller file. Indeed,
a subsequent part of the properties supported by a raw NAND chip are
also supported by SPI-NAND chips. So let's create a generic NAND chip
description which will be pulled by nand-controller.yaml and later by
spi-nand.yaml as well.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/linux-mtd/20211216111654.238086-5-miquel.raynal@bootlin.com

Documentation/devicetree/bindings/mtd/nand-chip.yaml

@@ -0,0 +1,70 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mtd/nand-chip.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: NAND Chip and NAND Controller Generic Binding
+
+maintainers:
+  - Miquel Raynal <miquel.raynal@bootlin.com>
+
+description: |
+  This file covers the generic description of a NAND chip. It implies that the
+  bus interface should not be taken into account: both raw NAND devices and
+  SPI-NAND devices are concerned by this description.
+
+properties:
+  reg:
+    description:
+      Contains the chip-select IDs.
+
+  nand-ecc-engine:
+    description: |
+      A phandle on the hardware ECC engine if any. There are
+      basically three possibilities:
+      1/ The ECC engine is part of the NAND controller, in this
+      case the phandle should reference the parent node.
+      2/ The ECC engine is part of the NAND part (on-die), in this
+      case the phandle should reference the node itself.
+      3/ The ECC engine is external, in this case the phandle should
+      reference the specific ECC engine node.
+    $ref: /schemas/types.yaml#/definitions/phandle
+
+  nand-use-soft-ecc-engine:
+    description: Use a software ECC engine.
+    type: boolean
+
+  nand-no-ecc-engine:
+    description: Do not use any ECC correction.
+    type: boolean
+
+  nand-ecc-algo:
+    description:
+      Desired ECC algorithm.
+    $ref: /schemas/types.yaml#/definitions/string
+    enum: [hamming, bch, rs]
+
+  nand-ecc-strength:
+    description:
+      Maximum number of bits that can be corrected per ECC step.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 1
+
+  nand-ecc-step-size:
+    description:
+      Number of data bytes covered by a single ECC step.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 1
+
+  secure-regions:
+    description:
+      Regions in the NAND chip which are protected using a secure element
+      like Trustzone. This property contains the start address and size of
+      the secure regions present.
+    $ref: /schemas/types.yaml#/definitions/uint64-matrix
+
+required:
+  - reg
+
+additionalProperties: true