[PATCH v4 1/1] dt-bindings: remoteproc: mtk,scp: Allow multiple memory regions for MT8188

[Arnab Layek]

The MT8188 SCP can use either one or two reserved memory regions:
- Required: Main SCP SRAM memory region (mandatory for SCP operation)
- Optional: SCP L1TCM memory region (Level 1 Tightly Coupled Memory,
  used for performance optimization when available, but not required
  for basic SCP functionality)

Other MediaTek SoCs (MT8183, MT8186, MT8192, MT8195) use only a single
memory region and must remain restricted to one region for backward
compatibility.

Update the base schema to allow 1-2 memory regions (minItems: 1,
maxItems: 2), following the pattern used by other MediaTek dt-bindings
like mediatek,vcodec-encoder.yaml where the base property defines a
permissive range accommodating all device variants.

Add two conditionals:
1. Explicitly restrict non-MT8188 devices to maxItems: 1
2. Document MT8188's two regions with descriptions (minItems: 1 makes
   the L1TCM region optional, allowing boards to specify 1-2 regions
   based on hardware configuration)

This approach maintains backward compatibility while enabling MT8188 to
specify 1-2 memory regions depending on board design and performance
requirements.

Signed-off-by: Arnab Layek <arnab.layek at mediatek.com>
---
 .../bindings/remoteproc/mtk,scp.yaml          | 45 ++++++++++++++++++-
 1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/remoteproc/mtk,scp.yaml b/Documentation/devicetree/bindings/remoteproc/mtk,scp.yaml
index bdbb12118da4..fca9b0675eae 100644
--- a/Documentation/devicetree/bindings/remoteproc/mtk,scp.yaml
+++ b/Documentation/devicetree/bindings/remoteproc/mtk,scp.yaml
@@ -55,7 +55,8 @@ properties:
       initializing SCP.
 
   memory-region:
-    maxItems: 1
+    minItems: 1
+    maxItems: 2
 
   cros-ec-rpmsg:
     $ref: /schemas/embedded-controller/google,cros-ec.yaml
@@ -123,7 +124,8 @@ patternProperties:
           initializing sub cores of multi-core SCP.
 
       memory-region:
-        maxItems: 1
+        minItems: 1
+        maxItems: 2
 
       cros-ec-rpmsg:
         $ref: /schemas/embedded-controller/google,cros-ec.yaml
@@ -205,6 +207,45 @@ allOf:
           items:
             - const: cfg
             - const: l1tcm
+  - if:
+      properties:
+        compatible:
+          enum:
+            - mediatek,mt8183-scp
+            - mediatek,mt8186-scp
+            - mediatek,mt8192-scp
+            - mediatek,mt8195-scp
+            - mediatek,mt8195-scp-dual
+    then:
+      properties:
+        memory-region:
+          maxItems: 1
+      patternProperties:
+        "^scp@[a-f0-9]+$":
+          properties:
+            memory-region:
+              maxItems: 1
+  - if:
+      properties:
+        compatible:
+          enum:
+            - mediatek,mt8188-scp
+            - mediatek,mt8188-scp-dual
+    then:
+      properties:
+        memory-region:
+          minItems: 1
+          items:
+            - description: Main SCP SRAM memory region
+            - description: Optional SCP L1TCM memory region
+      patternProperties:
+        "^scp@[a-f0-9]+$":
+          properties:
+            memory-region:
+              minItems: 1
+              items:
+                - description: Main SCP SRAM memory region
+                - description: Optional SCP L1TCM memory region
 
 additionalProperties: false
 
-- 
2.45.2