From b5c1a217552c3513977a9f1138b05de0bada8a52 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Cl=C3=A9ment=20Le=20Goffic?= <clement.legoffic@foss.st.com>
Date: Tue, 18 Nov 2025 16:07:58 +0100
Subject: [PATCH] dt-bindings: memory: introduce DDR4
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Introduce JEDEC compliant DDR bindings, that use new memory-props binding.

The DDR4 compatible can be made of explicit vendor names and part
numbers or be of the form "ddrX-YYYY,AAAA...-ZZ" when associated with an
SPD, where (according to JEDEC SPD4.1.2.L-6):
- YYYY is the manufacturer ID
- AAAA... is the part number
- ZZ is the revision ID

The former form is useful when the SDRAM vendor and part number are
known, for example, when memory is soldered on the board.
The latter form is useful when SDRAM nodes are created at runtime by
boot firmware that doesn't have access to static part number information.

Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
Signed-off-by: Clément Le Goffic <legoffic.clement@gmail.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20251118-b4-ddr-bindings-v9-2-a033ac5144da@gmail.com
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
---
 .../memory-controllers/ddr/jedec,ddr4.yaml    | 34 +++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/memory-controllers/ddr/jedec,ddr4.yaml

diff --git a/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,ddr4.yaml b/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,ddr4.yaml
new file mode 100644
index 0000000000000..928961c740261
--- /dev/null
+++ b/Documentation/devicetree/bindings/memory-controllers/ddr/jedec,ddr4.yaml
@@ -0,0 +1,34 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/memory-controllers/ddr/jedec,ddr4.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: DDR4 SDRAM compliant to JEDEC JESD79-4D
+
+maintainers:
+  - Krzysztof Kozlowski <krzk@kernel.org>
+
+allOf:
+  - $ref: jedec,sdram-props.yaml#
+
+properties:
+  compatible:
+    items:
+      - pattern: "^ddr4-[0-9a-f]{4},[a-z]{1,20}-[0-9a-f]{2}$"
+      - const: jedec,ddr4
+
+required:
+  - compatible
+  - density
+  - io-width
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    ddr {
+        compatible = "ddr4-00ff,azaz-ff", "jedec,ddr4";
+        density = <8192>;
+        io-width = <8>;
+    };
-- 
2.47.3