linux-kernel - [PATCH 2/3] dt-bindings: mtd: physmap: Allow using memory-region to access memory resources

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Message-Id: <20251117-mtd-memregion-v1-2-7b35611c79a6@bootlin.com>
Date: Mon, 17 Nov 2025 18:00:15 +0100
From: Gregory CLEMENT <gregory.clement@...tlin.com>
To: Rob Herring <robh@...nel.org>, Saravana Kannan <saravanak@...gle.com>, 
 Linus Walleij <linus.walleij@...aro.org>, 
 Miquel Raynal <miquel.raynal@...tlin.com>, 
 Richard Weinberger <richard@....at>, Vignesh Raghavendra <vigneshr@...com>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>
Cc: Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 Vladimir Kondratiev <vladimir.kondratiev@...ileye.com>, 
 Benoît Monin <benoit.monin@...tlin.com>, 
 Théo Lebrun <theo.lebrun@...tlin.com>, 
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, linux-mtd@...ts.infradead.org, 
 Gregory CLEMENT <gregory.clement@...tlin.com>
Subject: [PATCH 2/3] dt-bindings: mtd: physmap: Allow using memory-region
 to access memory resources

Enable access to memory resources not only via I/O address using reg,
but also through a portion of main memory using memory-region. To
achieve this, new compatible strings have been introduced: mtd-mem and
mtd-memro.

Signed-off-by: Gregory CLEMENT <gregory.clement@...tlin.com>
---
 .../devicetree/bindings/mtd/mtd-physmap.yaml       | 59 +++++++++++++++-------
 1 file changed, 40 insertions(+), 19 deletions(-)

diff --git a/Documentation/devicetree/bindings/mtd/mtd-physmap.yaml b/Documentation/devicetree/bindings/mtd/mtd-physmap.yaml
index 1b375dee83b0c..0f75a1204b263 100644
--- a/Documentation/devicetree/bindings/mtd/mtd-physmap.yaml
+++ b/Documentation/devicetree/bindings/mtd/mtd-physmap.yaml
@@ -13,10 +13,6 @@ description: |
   Flash chips (Memory Technology Devices) are often used for solid state
   file systems on embedded devices.
 
-allOf:
-  - $ref: mtd.yaml#
-  - $ref: /schemas/memory-controllers/mc-peripheral-props.yaml#
-
 properties:
   compatible:
     oneOf:
@@ -61,6 +57,8 @@ properties:
           - jedec-flash
           - mtd-ram
           - mtd-rom
+          - mtd-mem
+          - mtd-memro
 
   reg:
     description: |
@@ -116,6 +114,10 @@ properties:
     minItems: 1
     maxItems: 8
 
+  memory-region:
+    items:
+      - description: Memory regions to map into mtd
+
   '#address-cells':
     const: 1
 
@@ -129,21 +131,25 @@ properties:
 
 required:
   - compatible
-  - reg
-
-if:
-  properties:
-    compatible:
-      contains:
-        const: cortina,gemini-flash
-then:
-  properties:
-    syscon:
-      $ref: /schemas/types.yaml#/definitions/phandle
-      description:
-        Phandle to the syscon controller
-  required:
-    - syscon
+
+allOf:
+  - $ref: mtd.yaml#
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - mtd-mem
+              - mtd-memro
+    then:
+      required:
+        - memory-region
+      properties:
+        addr-gpios: false
+    else:
+      $ref: /schemas/memory-controllers/mc-peripheral-props.yaml#
+      required:
+        - reg
 
 unevaluatedProperties: false
 
@@ -223,4 +229,19 @@ examples:
             reg = <0 0x04000000>;
         };
     };
+
+  - |
+    /* An example using mtd-mem */
+    mem_logs: mem_logs@...00800 {
+        reg = <0x1 0x0000800 0x0 0x000f800>;
+        no-map;
+    };
+
+    sram {
+        compatible = "mtd-mem";
+        memory-region = <&mem_log>;
+        bank-width = <4>;
+        device-width = <1>;
+    };
+
 ...

-- 
2.51.0