[PATCH v6 1/7] dt-bindings: reset: microchip,rst: Allow to replace cpu-syscon by an additional reg item

[Herve Codina]

In the LAN966x PCI device use case, syscon cannot be used as syscon
devices do not support removal [1]. A syscon device is a core "system"
device and not a device available in some addon boards and so, it is not
supposed to be removed.

In order to remove the syscon device usage, allow the reset controller
to have a direct access to the address range it needs to use.

Link: https://lore.kernel.org/all/20240923100741.11277439@xxxxxxxxxxx/ [1]
Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
---
 .../bindings/reset/microchip,rst.yaml         | 35 ++++++++++++++++++-
 1 file changed, 34 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/reset/microchip,rst.yaml b/Documentation/devicetree/bindings/reset/microchip,rst.yaml
index f2da0693b05a..5164239a372c 100644
--- a/Documentation/devicetree/bindings/reset/microchip,rst.yaml
+++ b/Documentation/devicetree/bindings/reset/microchip,rst.yaml
@@ -25,12 +25,16 @@ properties:
       - microchip,lan966x-switch-reset
 
   reg:
+    minItems: 1
     items:
       - description: global control block registers
+      - description: cpu system block registers
 
   reg-names:
+    minItems: 1
     items:
       - const: gcb
+      - const: cpu
 
   "#reset-cells":
     const: 1
@@ -39,12 +43,29 @@ properties:
     $ref: /schemas/types.yaml#/definitions/phandle
     description: syscon used to access CPU reset
 
+allOf:
+  # Allow to use the second reg item instead of cpu-syscon
+  - if:
+      required:
+        - cpu-syscon
+    then:
+      properties:
+        reg:
+          maxItems: 1
+        reg-names:
+          maxItems: 1
+    else:
+      properties:
+        reg:
+          minItems: 2
+        reg-names:
+          minItems: 2
+
 required:
   - compatible
   - reg
   - reg-names
   - "#reset-cells"
-  - cpu-syscon
 
 additionalProperties: false
 
@@ -57,3 +78,15 @@ examples:
         #reset-cells = <1>;
         cpu-syscon = <&cpu_ctrl>;
     };
+
+    /*
+     * The following construction can be used if the cpu-syscon device is not
+     * present. This is the case when the LAN966x is used as a PCI device.
+     */
+    reset-controller@22010008 {
+        compatible = "microchip,lan966x-switch-reset";
+        reg = <0xe200400c 0x4>,
+              <0xe00c0000 0xa8>;
+        reg-names = "gcb", "cpu";
+        #reset-cells = <1>;
+    };
-- 
2.46.1