dt-bindings: hwmon: Add max6639

Add Devicetree binding documentation for Maxim MAX6639 temperature
monitor with PWM fan-speed controller.
Signed-off-by: Naresh Solanki <naresh.solanki@9elements.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20240528125122.1129986-1-naresh.solanki@9elements.com
[groeck: Dropped unnecessary '|' after description:]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/devicetree/bindings/hwmon/maxim,max6639.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+
+$id: http://devicetree.org/schemas/hwmon/maxim,max6639.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Maxim max6639
+
+maintainers:
+  - Naresh Solanki <naresh.solanki@9elements.com>
+
+description: |
+  The MAX6639 is a 2-channel temperature monitor with dual, automatic, PWM
+  fan-speed controller.  It monitors its own temperature and one external
+  diode-connected transistor or the temperatures of two external diode-connected
+  transistors, typically available in CPUs, FPGAs, or GPUs.
+
+  Datasheets:
+    https://datasheets.maximintegrated.com/en/ds/MAX6639-MAX6639F.pdf
+
+properties:
+  compatible:
+    enum:
+      - maxim,max6639
+
+  reg:
+    maxItems: 1
+
+  '#address-cells':
+    const: 1
+
+  '#size-cells':
+    const: 0
+
+  '#pwm-cells':
+    const: 3
+
+required:
+  - compatible
+  - reg
+
+patternProperties:
+  "^fan@[0-1]$":
+    type: object
+    description:
+      Represents the two fans and their specific configuration.
+
+    $ref: fan-common.yaml#
+
+    unevaluatedProperties: false
+
+    properties:
+      reg:
+        description:
+          The fan number.
+
+    required:
+      - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        fan1: fan-controller@10 {
+            compatible = "maxim,max6639";
+            reg = <0x10>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+            #pwm-cells = <3>;
+
+            fan@0 {
+                reg = <0x0>;
+                pulses-per-revolution = <2>;
+                max-rpm = <4000>;
+                target-rpm = <1000>;
+                pwms = <&fan1 0 25000 0>;
+            };
+
+            fan@1 {
+                reg = <0x1>;
+                pulses-per-revolution = <2>;
+                max-rpm = <8000>;
+                pwms = <&fan1 1 25000 0>;
+            };
+        };
+    };
+...