dt-bindings: nvmem: layouts: add fixed-layout

With the introduction of NVMEM layouts, new NVMEM content structures
should be defined as such. We should also try to convert / migrate
existing NVMEM content bindings to layouts.

This commit handles fixed NVMEM cells. So far they had to be defined
directly - as device subnodes. With this change it's allowed to put them
in the DT node named "nvmem-layout".

Having NVMEM cells in separated node is preferred as it draws a nice
line between NVMEM device and its content. It results in cleaner
bindings.

FWIW a very similar situation has happened to MTD devices and their
partitions: see commit 5d96ea42eb ("dt-bindings: mtd: Clarify all
partition subnodes").

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Message-ID: <20230611140330.154222-24-srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/nvmem/layouts/fixed-cell.yaml

@@ -0,0 +1,31 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/nvmem/layouts/fixed-cell.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Fixed offset & size NVMEM cell
+
+maintainers:
+  - Rafał Miłecki <rafal@milecki.pl>
+  - Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
+
+properties:
+  reg:
+    maxItems: 1
+
+  bits:
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    items:
+      - minimum: 0
+        maximum: 7
+        description:
+          Offset in bit within the address range specified by reg.
+      - minimum: 1
+        description:
+          Size in bit within the address range specified by reg.
+
+required:
+  - reg
+
+additionalProperties: true

Documentation/devicetree/bindings/nvmem/layouts/fixed-layout.yaml

@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/nvmem/layouts/fixed-layout.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: NVMEM layout for fixed NVMEM cells
+
+description:
+  Many NVMEM devices have hardcoded cells layout (offset and size of defined
+  NVMEM content doesn't change).
+
+  This binding allows defining such NVMEM layout with its cells. It can be used
+  on top of any NVMEM device.
+
+maintainers:
+  - Rafał Miłecki <rafal@milecki.pl>
+
+properties:
+  compatible:
+    const: fixed-layout
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 1
+
+patternProperties:
+  "@[a-f0-9]+$":
+    type: object
+    $ref: fixed-cell.yaml
+    unevaluatedProperties: false
+
+required:
+  - compatible
+
+additionalProperties: false
+
+examples:
+  - |
+    nvmem-layout {
+        compatible = "fixed-layout";
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        calibration@4000 {
+            reg = <0x4000 0x100>;
+        };
+    };

Documentation/devicetree/bindings/nvmem/layouts/nvmem-layout.yaml

@@ -18,16 +18,13 @@ description: |
   perform their parsing. The nvmem-layout container is here to describe these.
 
 oneOf:
+  - $ref: fixed-layout.yaml
   - $ref: kontron,sl28-vpd.yaml
   - $ref: onie,tlv-layout.yaml
 
 properties:
   compatible: true
 
-  '#address-cells': false
-
-  '#size-cells': false
-
 required:
   - compatible
 

Documentation/devicetree/bindings/nvmem/nvmem.yaml

@@ -49,23 +49,8 @@ properties:
 patternProperties:
   "@[0-9a-f]+(,[0-7])?$":
     type: object
-
-    properties:
-      reg:
-        maxItems: 1
-        description:
-          Offset and size in bytes within the storage device.
-
-      bits:
-        $ref: /schemas/types.yaml#/definitions/uint32-array
-        items:
-          - minimum: 0
-            maximum: 7
-            description:
-              Offset in bit within the address range specified by reg.
-          - minimum: 1
-            description:
-              Size in bit within the address range specified by reg.
+    $ref: layouts/fixed-cell.yaml
+    deprecated: true
 
 additionalProperties: true