From:   =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <zajec5@gmail.com>
To:     Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
Cc:     Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Michael Walle <michael@walle.cc>, devicetree@vger.kernel.org,
        linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org,
        =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
Subject: [PATCH] dt-bindings: nvmem: allow MTD to be explicitly an NVMEM provider
Date:   Fri, 10 Mar 2023 11:53:30 +0100
Message-Id: <20230310105330.14181-1-zajec5@gmail.com>
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From: Rafał Miłecki <rafal@milecki.pl>

There are a lot of devices with NVMEM content stored in MTD devices in
relevant partitions. Add a DT binding for marking such partitions.

Note: Linux already treats every MTD partition as NVMEM provider so in
general it doesn't need to care about this binding. It's meant just to
make DT clearer in describing hardware.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
As explained in commit body this isn't really needed for Linux. I
thought it'd be a small nice addition for writing clear DTS files.
---
 .../devicetree/bindings/nvmem/mtd.yaml        | 52 +++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/nvmem/mtd.yaml

diff --git a/Documentation/devicetree/bindings/nvmem/mtd.yaml b/Documentation/devicetree/bindings/nvmem/mtd.yaml
new file mode 100644
index 000000000000..7435b2803cf9
--- /dev/null
+++ b/Documentation/devicetree/bindings/nvmem/mtd.yaml
@@ -0,0 +1,52 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/nvmem/mtd.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: MTD access based NVMEM
+
+description: |
+  MTD partitions can be NVMEM providers. This binding allows explicitly marking
+  such partitions.
+
+  The exact way of handling MTD partition content (NVMEM cells) should be
+  described using a proper NVMEM layout.
+
+maintainers:
+  - Rafał Miłecki <rafal@milecki.pl>
+
+allOf:
+  - $ref: nvmem.yaml#
+  - $ref: /schemas/mtd/partitions/partition.yaml#
+
+properties:
+  compatible:
+    const: mtd-nvmem
+
+  reg:
+    maxItems: 1
+
+required:
+  - reg
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    partitions {
+        compatible = "fixed-partitions";
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        partition@0 {
+            compatible = "mtd-nvmem";
+            reg = <0x0 0x40000>;
+            label = "device-data";
+
+            nvmem-layout {
+                /* Just a dummy example: Kontron can be found on OTP actually */
+                compatible = "kontron,sl28-vpd";
+            };
+        };
+    };
-- 
2.34.1