dt-bindings: adc: provide max34408/9 device tree binding document

The hardware binding for i2c current monitoring device with overcurrent
control.
Signed-off-by: Ivan Mikhaylov <fr0st61te@gmail.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20231014211254.16719-2-fr0st61te@gmail.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/adc/maxim,max34408.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/maxim,max34408.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Maxim MAX34408/MAX34409 current monitors with overcurrent control
+
+maintainers:
+  - Ivan Mikhaylov <fr0st61te@gmail.com>
+
+description: |
+  The MAX34408/MAX34409 are two- and four-channel current monitors that are
+  configured and monitored with a standard I2C/SMBus serial interface. Each
+  unidirectional current sensor offers precision high-side operation with a
+  low full-scale sense voltage. The devices automatically sequence through
+  two or four channels and collect the current-sense samples and average them
+  to reduce the effect of impulse noise. The raw ADC samples are compared to
+  user-programmable digital thresholds to indicate overcurrent conditions.
+  Overcurrent conditions trigger a hardware output to provide an immediate
+  indication to shut down any necessary external circuitry.
+
+  Specifications about the devices can be found at:
+  https://www.analog.com/media/en/technical-documentation/data-sheets/MAX34408-MAX34409.pdf
+
+properties:
+  compatible:
+    enum:
+      - maxim,max34408
+      - maxim,max34409
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 0
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  powerdown-gpios:
+    description:
+      Shutdown Output. Open-drain output. This output transitions to high impedance
+      when any of the digital comparator thresholds are exceeded as long as the ENA
+      pin is high.
+    maxItems: 1
+
+  powerdown-status-gpios:
+    description:
+      SHTDN Enable Input. CMOS digital input. Connect to GND to clear the latch and
+      unconditionally deassert (force low) the SHTDN output and reset the shutdown
+      delay. Connect to VDD to enable normal latch operation of the SHTDN output.
+    maxItems: 1
+
+  vdd-supply: true
+
+patternProperties:
+  "^channel@[0-3]$":
+    $ref: adc.yaml
+    type: object
+    description:
+      Represents the internal channels of the ADC.
+
+    properties:
+      reg:
+        items:
+          - minimum: 0
+            maximum: 3
+
+      maxim,rsense-val-micro-ohms:
+        description:
+          Adjust the Rsense value to monitor higher or lower current levels for
+          input.
+        enum: [250, 500, 1000, 5000, 10000, 50000, 100000, 200000, 500000]
+        default: 1000
+
+    required:
+      - reg
+      - maxim,rsense-val-micro-ohms
+
+    unevaluatedProperties: false
+
+required:
+  - compatible
+  - reg
+
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: maxim,max34408
+    then:
+      patternProperties:
+        "^channel@[2-3]$": false
+        "^channel@[0-1]$":
+          properties:
+            reg:
+              maximum: 1
+    else:
+      patternProperties:
+        "^channel@[0-3]$":
+          properties:
+            reg:
+              maximum: 3
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@1e {
+              compatible = "maxim,max34409";
+              reg = <0x1e>;
+              powerdown-gpios = <&gpio0 1 GPIO_ACTIVE_LOW>;
+              powerdown-status-gpios = <&gpio0 2 GPIO_ACTIVE_HIGH>;
+
+              #address-cells = <1>;
+              #size-cells = <0>;
+
+              channel@0 {
+                  reg = <0x0>;
+                  maxim,rsense-val-micro-ohms = <5000>;
+              };
+
+              channel@1 {
+                  reg = <0x1>;
+                  maxim,rsense-val-micro-ohms = <10000>;
+             };
+        };
+    };