linux-kernel - [PATCH v9 2/7] dt-bindings: memory: introduce DDR4

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Message-Id: <20251118-b4-ddr-bindings-v9-2-a033ac5144da@gmail.com>
Date: Tue, 18 Nov 2025 16:07:58 +0100
From: Clément Le Goffic <legoffic.clement@...il.com>
To: Krzysztof Kozlowski <krzk@...nel.org>, Rob Herring <robh@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Julius Werner <jwerner@...omium.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Maxime Coquelin <mcoquelin.stm32@...il.com>, 
 Alexandre Torgue <alexandre.torgue@...s.st.com>
Cc: linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-stm32@...md-mailman.stormreply.com, 
 linux-arm-kernel@...ts.infradead.org, 
 Clément Le Goffic <legoffic.clement@...il.com>, 
 Clément Le Goffic <clement.legoffic@...s.st.com>
Subject: [PATCH v9 2/7] dt-bindings: memory: introduce DDR4

From: Clément Le Goffic <clement.legoffic@...s.st.com>

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@...s.st.com>
Signed-off-by: Clément Le Goffic <legoffic.clement@...il.com>
---
 .../memory-controllers/ddr/jedec,ddr4.yaml         | 34 ++++++++++++++++++++++
 1 file changed, 34 insertions(+)

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 000000000000..928961c74026
--- /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@...nel.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>;
+    };

-- 
2.43.0