dt-bindings: mtd: convert "fixed-partitions" to the json-schema

This standardizes its documentation, allows validating with Makefile
checks and helps writing DTS files.

Noticeable changes:
1. Dropped "Partitions can be represented by sub-nodes of a flash
   device." as we also support subpartitions (don't have to be part of
   flash device node)
2. Dropped "to Linux" as bindings are meant to be os agnostic.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Link: https://lore.kernel.org/r/20201210172352.31632-1-zajec5@gmail.comSigned-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/mtd/partition.txt

@@ -24,137 +24,10 @@ another partitioning method.
 Available bindings are listed in the "partitions" subdirectory.
 
 
-Fixed Partitions
-================
-
-Partitions can be represented by sub-nodes of a flash device. This can be used
-on platforms which have strong conventions about which portions of a flash are
-used for what purposes, but which don't use an on-flash partition table such
-as RedBoot.
-
-The partition table should be a subnode of the flash node and should be named
-'partitions'. This node should have the following property:
-- compatible : (required) must be "fixed-partitions"
-Partitions are then defined in subnodes of the partitions node.
+Deprecated: partitions defined in flash node
+============================================
 
 For backwards compatibility partitions as direct subnodes of the flash device are
 supported. This use is discouraged.
 NOTE: also for backwards compatibility, direct subnodes that have a compatible
 string are not considered partitions, as they may be used for other bindings.
-
-#address-cells & #size-cells must both be present in the partitions subnode of the
-flash device. There are two valid values for both:
-<1>: for partitions that require a single 32-bit cell to represent their
-     size/address (aka the value is below 4 GiB)
-<2>: for partitions that require two 32-bit cells to represent their
-     size/address (aka the value is 4 GiB or greater).
-
-Required properties:
-- reg : The partition's offset and size within the flash
-
-Optional properties:
-- label : The label / name for this partition.  If omitted, the label is taken
-  from the node name (excluding the unit address).
-- read-only : This parameter, if present, is a hint to Linux that this
-  partition should only be mounted read-only. This is usually used for flash
-  partitions containing early-boot firmware images or data which should not be
-  clobbered.
-- lock : Do not unlock the partition at initialization time (not supported on
-  all devices)
-- slc-mode: This parameter, if present, allows one to emulate SLC mode on a
-  partition attached to an MLC NAND thus making this partition immune to
-  paired-pages corruptions
-
-Examples:
-
-
-flash@0 {
-	partitions {
-		compatible = "fixed-partitions";
-		#address-cells = <1>;
-		#size-cells = <1>;
-
-		partition@0 {
-			label = "u-boot";
-			reg = <0x0000000 0x100000>;
-			read-only;
-		};
-
-		uimage@100000 {
-			reg = <0x0100000 0x200000>;
-		};
-	};
-};
-
-flash@1 {
-	partitions {
-		compatible = "fixed-partitions";
-		#address-cells = <1>;
-		#size-cells = <2>;
-
-		/* a 4 GiB partition */
-		partition@0 {
-			label = "filesystem";
-			reg = <0x00000000 0x1 0x00000000>;
-		};
-	};
-};
-
-flash@2 {
-	partitions {
-		compatible = "fixed-partitions";
-		#address-cells = <2>;
-		#size-cells = <2>;
-
-		/* an 8 GiB partition */
-		partition@0 {
-			label = "filesystem #1";
-			reg = <0x0 0x00000000 0x2 0x00000000>;
-		};
-
-		/* a 4 GiB partition */
-		partition@200000000 {
-			label = "filesystem #2";
-			reg = <0x2 0x00000000 0x1 0x00000000>;
-		};
-	};
-};
-
-flash@3 {
-	partitions {
-		compatible = "fixed-partitions";
-		#address-cells = <1>;
-		#size-cells = <1>;
-
-		partition@0 {
-			label = "bootloader";
-			reg = <0x000000 0x100000>;
-			read-only;
-		};
-
-		firmware@100000 {
-			label = "firmware";
-			reg = <0x100000 0xe00000>;
-			compatible = "brcm,trx";
-		};
-
-		calibration@f00000 {
-			label = "calibration";
-			reg = <0xf00000 0x100000>;
-			compatible = "fixed-partitions";
-			ranges = <0 0xf00000 0x100000>;
-			#address-cells = <1>;
-			#size-cells = <1>;
-
-			partition@0 {
-				label = "wifi0";
-				reg = <0x000000 0x080000>;
-			};
-
-			partition@80000 {
-				label = "wifi1";
-				reg = <0x080000 0x080000>;
-			};
-		};
-	};
-};

Documentation/devicetree/bindings/mtd/partitions/fixed-partitions.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mtd/partitions/fixed-partitions.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Fixed partitions
+
+description: |
+  This binding can be used on platforms which have strong conventions about
+  which portions of a flash are used for what purposes, but which don't use an
+  on-flash partition table such as RedBoot.
+
+  The partition table should be a node named "partitions". Partitions are then
+  defined as subnodes.
+
+maintainers:
+  - Rafał Miłecki <rafal@milecki.pl>
+
+properties:
+  compatible:
+    const: fixed-partitions
+
+  "#address-cells": true
+
+  "#size-cells": true
+
+patternProperties:
+  "@[0-9a-f]+$":
+    description: node describing a single flash partition
+    type: object
+
+    properties:
+      reg:
+        description: partition's offset and size within the flash
+        maxItems: 1
+
+      label:
+        description: The label / name for this partition. If omitted, the label
+          is taken from the node name (excluding the unit address).
+
+      read-only:
+        description: This parameter, if present, is a hint that this partition
+          should only be mounted read-only. This is usually used for flash
+          partitions containing early-boot firmware images or data which should
+          not be clobbered.
+        type: boolean
+
+      lock:
+        description: Do not unlock the partition at initialization time (not
+          supported on all devices)
+        type: boolean
+
+      slc-mode:
+        description: This parameter, if present, allows one to emulate SLC mode
+          on a partition attached to an MLC NAND thus making this partition
+          immune to paired-pages corruptions
+        type: boolean
+
+    required:
+      - reg
+
+required:
+  - "#address-cells"
+  - "#size-cells"
+
+additionalProperties: true
+
+examples:
+  - |
+    partitions {
+        compatible = "fixed-partitions";
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        partition@0 {
+            label = "u-boot";
+            reg = <0x0000000 0x100000>;
+            read-only;
+        };
+
+        uimage@100000 {
+            reg = <0x0100000 0x200000>;
+        };
+    };
+  - |
+    partitions {
+        compatible = "fixed-partitions";
+        #address-cells = <1>;
+        #size-cells = <2>;
+
+        /* a 4 GiB partition */
+        partition@0 {
+            label = "filesystem";
+            reg = <0x00000000 0x1 0x00000000>;
+        };
+    };
+  - |
+    partitions {
+        compatible = "fixed-partitions";
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        /* an 8 GiB partition */
+        partition@0 {
+            label = "filesystem #1";
+            reg = <0x0 0x00000000 0x2 0x00000000>;
+        };
+
+        /* a 4 GiB partition */
+        partition@200000000 {
+            label = "filesystem #2";
+            reg = <0x2 0x00000000 0x1 0x00000000>;
+        };
+    };
+  - |
+    partitions {
+        compatible = "fixed-partitions";
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        partition@0 {
+            label = "bootloader";
+            reg = <0x000000 0x100000>;
+            read-only;
+        };
+
+        firmware@100000 {
+            compatible = "brcm,trx";
+            label = "firmware";
+            reg = <0x100000 0xe00000>;
+        };
+
+        calibration@f00000 {
+            compatible = "fixed-partitions";
+            label = "calibration";
+            reg = <0xf00000 0x100000>;
+            ranges = <0 0xf00000 0x100000>;
+            #address-cells = <1>;
+            #size-cells = <1>;
+
+            partition@0 {
+                label = "wifi0";
+                reg = <0x000000 0x080000>;
+            };
+
+            partition@80000 {
+                label = "wifi1";
+                reg = <0x080000 0x080000>;
+            };
+        };
+    };