dt-bindings: hwmon: isl68137: add bindings to support voltage dividers

Add devicetree bindings to support declaring optional voltage dividers to
the rail outputs of supported digital multiphase regulators. Some
applications require Vout to exceed the voltage range that the Vsense pin
can detect. This binding definition allows users to define the
characteristics of a voltage divider placed between Vout and the Vsense
pin for any rail powered by the device.

These bindings copy the vout-voltage-divider property defined in the
maxim,max20730 bindings schema since it is the best fit for the use case
of scaling hwmon PMBus telemetry. The generic voltage-divider property
used by many iio drivers was determined to be a poor fit because that
schema is tied directly to iio for the purpose of scaling io-channel
voltages and the isl68137 driver is not an iio driver.

New schema file named isil,isl68137.yaml to align with the corresponding
driver name and pre-existing bindings ported from trivial bindings.
However, all new device bindings use renesas as the vendor prefix
since Renesas acquired Intersil and now maintains all documentation
for the devices.

Signed-off-by: Grant Peltier <[email protected]>
Reviewed-by: Rob Herring (Arm) <[email protected]>
Message-ID: <f7ac200e982961ff733de27a5c4505c04d68b6f3.1731439797.git.grantpeltier93@gmail.com>
Signed-off-by: Guenter Roeck <[email protected]>

Author: gfpeltier

Documentation/devicetree/bindings/hwmon/pmbus/isil,isl68137.yaml

@@ -0,0 +1,148 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+
+$id: http://devicetree.org/schemas/hwmon/pmbus/isil,isl68137.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Renesas Digital Multiphase Voltage Regulators with PMBus
+
+maintainers:
+  - Grant Peltier <[email protected]>
+
+description: |
+  Renesas digital multiphase voltage regulators with PMBus.
+  https://www.renesas.com/en/products/power-management/multiphase-power/multiphase-dcdc-switching-controllers
+
+properties:
+  compatible:
+    enum:
+      - isil,isl68137
+      - renesas,isl68220
+      - renesas,isl68221
+      - renesas,isl68222
+      - renesas,isl68223
+      - renesas,isl68224
+      - renesas,isl68225
+      - renesas,isl68226
+      - renesas,isl68227
+      - renesas,isl68229
+      - renesas,isl68233
+      - renesas,isl68239
+      - renesas,isl69222
+      - renesas,isl69223
+      - renesas,isl69224
+      - renesas,isl69225
+      - renesas,isl69227
+      - renesas,isl69228
+      - renesas,isl69234
+      - renesas,isl69236
+      - renesas,isl69239
+      - renesas,isl69242
+      - renesas,isl69243
+      - renesas,isl69247
+      - renesas,isl69248
+      - renesas,isl69254
+      - renesas,isl69255
+      - renesas,isl69256
+      - renesas,isl69259
+      - isil,isl69260
+      - renesas,isl69268
+      - isil,isl69269
+      - renesas,isl69298
+      - renesas,raa228000
+      - renesas,raa228004
+      - renesas,raa228006
+      - renesas,raa228228
+      - renesas,raa229001
+      - renesas,raa229004
+
+  reg:
+    maxItems: 1
+
+  '#address-cells':
+    const: 1
+
+  '#size-cells':
+    const: 0
+
+patternProperties:
+  "^channel@([0-3])$":
+    type: object
+    description:
+      Container for properties specific to a particular channel (rail).
+
+    properties:
+      reg:
+        description: The channel (rail) index.
+        items:
+          minimum: 0
+          maximum: 3
+
+      vout-voltage-divider:
+        description: |
+          Resistances of a voltage divider placed between Vout and the voltage
+          sense (Vsense) pin for the given channel (rail). It has two numbers
+          representing the resistances of the voltage divider provided as
+          <Rout Rtotal> which yields an adjusted Vout as
+          Vout_adj = Vout * Rtotal / Rout given the original Vout as reported
+          by the Vsense pin. Given a circuit configuration similar to the one
+          below, Rtotal = R1 + Rout.
+
+            Vout ----.
+                     |
+                  .-----.
+                  | R1  |
+                  '-----'
+                     |
+                     +---- Vsense
+                     |
+                  .-----.
+                  | Rout|
+                  '-----'
+                     |
+                    GND
+
+        $ref: /schemas/types.yaml#/definitions/uint32-array
+        minItems: 2
+        maxItems: 2
+
+    required:
+      - reg
+
+    additionalProperties: false
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      isl68239@60 {
+        compatible = "isil,isl68137";
+        reg = <0x60>;
+      };
+    };
+  - |
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      isl68239@60 {
+        compatible = "renesas,isl68239";
+        reg = <0x60>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        channel@0 {
+          reg = <0>;
+          vout-voltage-divider = <1000 2000>;  // Reported Vout/Pout would be scaled by 2
+        };
+      };
+    };

Documentation/devicetree/bindings/trivial-devices.yaml

@@ -153,12 +153,6 @@ properties:
           - isil,isl29028
             # Intersil ISL29030 Ambient Light and Proximity Sensor
           - isil,isl29030
-            # Intersil ISL68137 Digital Output Configurable PWM Controller
-          - isil,isl68137
-            # Intersil ISL69260 PMBus Voltage Regulator
-          - isil,isl69260
-            # Intersil ISL69269 PMBus Voltage Regulator
-          - isil,isl69269
             # Intersil ISL76682 Ambient Light Sensor
           - isil,isl76682
             # JEDEC JESD300 (SPD5118) Hub and Serial Presence Detect