[PATCH v4 4/7] dt-bindings: watchdog: renesas,r9a09g057-wdt: Add CPG/MSSR syscon support

From: Lad Prabhakar <[email protected]>

On the Renesas RZ/T2H SoC, the Watchdog Timer Control Register (WDTDCR)
resides within the CPG/MSSR block rather than the WDT address space
itself.

Previously, this was handled by including a second register range in the
"reg" property. However, this is architecturally incorrect as the CPG/MSSR
block consists of two distinct regions (0x80280000 and 0x81280000) that
contain registers for multiple peripheral blocks.

Since the CPG/MSSR block is a multi-function block, introduce the
"renesas,sysc" phandle-array property to allow the WDT driver to access
its control register via this shared regmap.

Mark the use of a second "reg" entry as deprecated in favor of the
new phandle-array approach for SoCs that require WDTDCR access.

Signed-off-by: Lad Prabhakar <[email protected]>
Reviewed-by: Rob Herring (Arm) <[email protected]>
---
v3->v4:
- Added RB tag from Rob.

v2->v3:
- Updated property name to "renesas,sysc"
- Updated description about deprecation and use of the new
  phandle-array property.
- Updated commit message

v1->v2:
- No change.
---
 .../watchdog/renesas,r9a09g057-wdt.yaml       | 29 +++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/watchdog/renesas,r9a09g057-wdt.yaml b/Documentation/devicetree/bindings/watchdog/renesas,r9a09g057-wdt.yaml
index 975c5aa4d747..322b6921c147 100644
--- a/Documentation/devicetree/bindings/watchdog/renesas,r9a09g057-wdt.yaml
+++ b/Documentation/devicetree/bindings/watchdog/renesas,r9a09g057-wdt.yaml
@@ -48,6 +48,17 @@ properties:
   resets:
     maxItems: 1
 
+  renesas,sysc:
+    description:
+      System controller registers control the start/stop of the WDT, and halt debug.
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    items:
+      - items:
+          - description: phandle to system controller
+          - description: watchdog IP instance index
+            minimum: 0
+            maximum: 5
+
   timeout-sec: true
 
 required:
@@ -73,15 +84,29 @@ allOf:
           minItems: 2
         clock-names:
           minItems: 2
+        renesas,sysc: false
     else:
       properties:
         clocks:
           maxItems: 1
         clock-names:
           maxItems: 1
-        reg:
-          minItems: 2
         resets: false
+      allOf:
+        - if:
+            required:
+              - renesas,sysc
+          then:
+            properties:
+              reg:
+                maxItems: 1
+          else:
+            properties:
+              reg:
+                description: Deprecated. Use the renesas,sysc property along with
+                             the watchdog IP instance index instead.
+                minItems: 2
+                deprecated: true
 
 additionalProperties: false
 
-- 
2.43.0