dt-bindings: iio: magnetometer: document the Allegro MicroSystems ALS31300 3-D Linear Hall Effect Sensor

Document the bindings for the Allegro MicroSystems ALS31300 3-D Linear
Hall Effect Sensor controller by an I2C interface, mainly used in 3D
head-on motion sensing applications.

The device can be configured with different sensitivities in factory,
but the sensitivity value used to calculate value into the Gauss unit
is not available from registers, thus the sensitivity is provided by
the compatible/device-id string which is based on the part number as
described in the datasheet page 2.

Datasheet: https://www.allegromicro.com/-/media/files/datasheets/als31300-datasheet.pdf
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patch.msgid.link/20241030-topic-input-upstream-als31300-v4-2-494297c9e50a@linaro.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/magnetometer/allegromicro,als31300.yaml

@@ -0,0 +1,46 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/magnetometer/allegromicro,als31300.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Allegro MicroSystems ALS31300 3-D Linear Hall Effect sensor
+
+maintainers:
+  - Neil Armstrong <neil.armstrong@linaro.org>
+
+properties:
+  $nodename:
+    pattern: '^magnetometer@[0-9a-f]+$'
+
+  compatible:
+    enum:
+      - allegromicro,als31300-500 # Factory configured at 500 Gauss input range
+      - allegromicro,als31300-1000 # Factory configured at 1000 Gauss input range
+      - allegromicro,als31300-2000 # Factory configured at 2000 Gauss input range
+
+  reg:
+    maxItems: 1
+
+  vcc-supply:
+    description: 5.5V supply
+
+  interrupts:
+    maxItems: 1
+
+required:
+  - compatible
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+      magnetometer@61 {
+        compatible = "allegromicro,als31300-500";
+        reg = <0x61>;
+        vcc-supply = <&hall_vcc>;
+      };
+    };