dt-bindings: power: supply: document Samsung S2MU005 battery fuel gauge

Samsung S2MU005 is a PMIC device which has LED controllers, an MUIC and
a battery charger. The battery charger is paired with an independent
device connected via I2C which can be used to access various metrics of
the battery. Document the device as a schema.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Link: https://patch.msgid.link/20260304-s2mu005-fuelgauge-v3-1-e4dc4e47cde8@disroot.org
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

Documentation/devicetree/bindings/power/supply/samsung,s2mu005-fuel-gauge.yaml

@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/power/supply/samsung,s2mu005-fuel-gauge.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Battery Fuel Gauge for Samsung S2M series PMICs
+
+maintainers:
+  - Kaustabh Chakraborty <kauschluss@disroot.org>
+
+allOf:
+  - $ref: power-supply.yaml#
+
+properties:
+  compatible:
+    enum:
+      - samsung,s2mu005-fuel-gauge
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      fuel-gauge@3b {
+        compatible = "samsung,s2mu005-fuel-gauge";
+        reg = <0x3b>;
+
+        interrupt-parent = <&gpa0>;
+        interrupts = <3 IRQ_TYPE_EDGE_BOTH>;
+
+        monitored-battery = <&battery>;
+      };
+    };