dt-bindings: net: pse-pd: Add another way of describing several PSE PIs

PSE PI setup may encompass multiple PSE controllers or auxiliary circuits
that collectively manage power delivery to one Ethernet port.
Such configurations might support a range of PoE standards and require
the capability to dynamically configure power delivery based on the
operational mode (e.g., PoE2 versus PoE4) or specific requirements of
connected devices. In these instances, a dedicated PSE PI node becomes
essential for accurately documenting the system architecture. This node
would serve to detail the interactions between different PSE controllers,
the support for various PoE modes, and any additional logic required to
coordinate power delivery across the network infrastructure.

The old usage of "#pse-cells" is unsuficient as it carries only the PSE PI
index information.

Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
Link: https://lore.kernel.org/r/20240417-feature_poe-v9-8-242293fd1900@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/devicetree/bindings/net/pse-pd/pse-controller.yaml

@@ -13,6 +13,7 @@ description: Binding for the Power Sourcing Equipment (PSE) as defined in the
 
 maintainers:
   - Oleksij Rempel <o.rempel@pengutronix.de>
+  - Kory Maincent <kory.maincent@bootlin.com>
 
 properties:
   $nodename:
@@ -22,11 +23,105 @@ properties:
     description:
       Used to uniquely identify a PSE instance within an IC. Will be
       0 on PSE nodes with only a single output and at least 1 on nodes
-      controlling several outputs.
+      controlling several outputs which are not described in the pse-pis
+      subnode. This property is deprecated, please use pse-pis instead.
     enum: [0, 1]
 
-required:
-  - "#pse-cells"
+  pse-pis:
+    type: object
+    description:
+      Overview of the PSE PIs provided by the controller.
+
+    properties:
+      "#address-cells":
+        const: 1
+
+      "#size-cells":
+        const: 0
+
+    required:
+      - "#address-cells"
+      - "#size-cells"
+
+    patternProperties:
+      "^pse-pi@[0-9a-f]+$":
+        type: object
+        description:
+          PSE PI for power delivery via pairsets, compliant with IEEE
+          802.3-2022, Section 145.2.4. Each pairset comprises a positive and
+          a negative VPSE pair, adhering to the pinout configurations
+          detailed in the standard.
+          See Documentation/networking/pse-pd/pse-pi.rst for details.
+
+        properties:
+          reg:
+            description:
+              Address describing the PSE PI index.
+            maxItems: 1
+
+          "#pse-cells":
+            const: 0
+
+          pairset-names:
+            $ref: /schemas/types.yaml#/definitions/string-array
+            description:
+              Names of the pairsets as per IEEE 802.3-2022, Section 145.2.4.
+              Each name should correspond to a phandle in the 'pairset'
+              property pointing to the power supply for that pairset.
+            minItems: 1
+            maxItems: 2
+            items:
+              enum:
+                - alternative-a
+                - alternative-b
+
+          pairsets:
+            $ref: /schemas/types.yaml#/definitions/phandle-array
+            description:
+              List of phandles, each pointing to the power supply for the
+              corresponding pairset named in 'pairset-names'. This property
+              aligns with IEEE 802.3-2022, Section 33.2.3 and 145.2.4.
+              PSE Pinout Alternatives (as per IEEE 802.3-2022 Table 145\u20133)
+              |-----------|---------------|---------------|---------------|---------------|
+              | Conductor | Alternative A | Alternative A | Alternative B | Alternative B |
+              |           |    (MDI-X)    |     (MDI)     |      (X)      |      (S)      |
+              |-----------|---------------|---------------|---------------|---------------|
+              | 1         | Negative VPSE | Positive VPSE | -             | -             |
+              | 2         | Negative VPSE | Positive VPSE | -             | -             |
+              | 3         | Positive VPSE | Negative VPSE | -             | -             |
+              | 4         | -             | -             | Negative VPSE | Positive VPSE |
+              | 5         | -             | -             | Negative VPSE | Positive VPSE |
+              | 6         | Positive VPSE | Negative VPSE | -             | -             |
+              | 7         | -             | -             | Positive VPSE | Negative VPSE |
+              | 8         | -             | -             | Positive VPSE | Negative VPSE |
+            minItems: 1
+            maxItems: 2
+
+          polarity-supported:
+            $ref: /schemas/types.yaml#/definitions/string-array
+            description:
+              Polarity configuration supported by the PSE PI pairsets.
+            minItems: 1
+            maxItems: 4
+            items:
+              enum:
+                - MDI-X
+                - MDI
+                - X
+                - S
+
+          vpwr-supply:
+            description: Regulator power supply for the PSE PI.
+
+        required:
+          - reg
+          - "#pse-cells"
+
+oneOf:
+  - required:
+      - "#pse-cells"
+  - required:
+      - pse-pis
 
 additionalProperties: true