dt-bindings: iio: adc: add binding for pac1921

Add binging for Microchip PAC1921 Power/Current monitor
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Matteo Martelli <matteomartelli3@gmail.com>
Link: https://patch.msgid.link/20240724-iio-pac1921-v4-1-723698e903a3@gmail.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/adc/microchip,pac1921.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/microchip,pac1921.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microchip PAC1921 High-Side Power/Current Monitor with Anaog Output
+
+maintainers:
+  - Matteo Martelli <matteomartelli3@gmail.com>
+
+description: |
+  The PAC1921 is a power/current monitoring device with an analog output
+  and I2C/SMBus interface.
+
+  Datasheet can be found here:
+  https://ww1.microchip.com/downloads/en/DeviceDoc/PAC1921-Data-Sheet-DS20005293E.pdf
+
+properties:
+  compatible:
+    const: microchip,pac1921
+
+  reg:
+    maxItems: 1
+
+  vdd-supply: true
+
+  "#io-channel-cells":
+    const: 1
+
+  shunt-resistor-micro-ohms:
+    description:
+      Value in micro Ohms of the shunt resistor connected between
+      the SENSE+ and SENSE- inputs, across which the current is measured.
+      Value is needed to compute the scaling of the measured current.
+
+  label:
+    description: Unique name to identify which device this is.
+
+  read-integrate-gpios:
+    description:
+      READ/INT input pin to control the current state of the device, either in
+      the INTEGRATE state when driven high, or in the READ state when driven low.
+      When not connected the pin is floating and it can be overridden by the
+      INT_EN register bit after asserting the READ/INT_OVR register bit.
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - vdd-supply
+  - shunt-resistor-micro-ohms
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@4c {
+            compatible = "microchip,pac1921";
+            reg = <0x4c>;
+            vdd-supply = <&vdd>;
+            #io-channel-cells = <1>;
+            label = "vbat";
+            shunt-resistor-micro-ohms = <10000>;
+        };
+    };
+...