iio: light: Add DT bindings for GP2AP002

This adds device tree bindings for the GP2AP002 light
and proximity sensor.

As with other early proximity sensors (~2010) the light
sensor and proximity sensors were combined into a single
component.

Cc: Stephan Gerhold <stephan@gerhold.net>
Cc: Minkyu Kang <mk7.kang@samsung.com>
Cc: Paweł Chmiel <pawel.mikolaj.chmiel@gmail.com>
Cc: Jonathan Bakker <xc-racer2@live.ca>
Cc: Oskar Andero <oskar.andero@gmail.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: devicetree@vger.kernel.org
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/light/sharp,gp2ap002.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/light/sharp,gp2ap002.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Sharp GP2AP002A00F and GP2AP002S00F proximity and ambient light sensors
+
+maintainers:
+  - Linus Walleij <linus.walleij@linaro.org>
+
+description: |
+  Proximity and ambient light sensor with IR LED for the proximity
+  sensing and an analog output for light intensity. The ambient light
+  sensor output is not available on the GP2AP002S00F variant.
+
+properties:
+  compatible:
+    enum:
+      - sharp,gp2ap002a00f
+      - sharp,gp2ap002s00f
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+    description: an interrupt for proximity, usually a GPIO line
+
+  vdd-supply:
+    description: VDD power supply a phandle to a regulator
+
+  vio-supply:
+    description: VIO power supply a phandle to a regulator
+
+  io-channels:
+    maxItems: 1
+    description: ALSOUT ADC channel to read the ambient light
+
+  io-channel-names:
+    const: alsout
+
+  sharp,proximity-far-hysteresis:
+    $ref: /schemas/types.yaml#/definitions/uint8
+    description: |
+      Hysteresis setting for "far" object detection, this setting is
+      device-unique and adjust the optical setting for proximity detection
+      of a "far away" object in front of the sensor.
+
+  sharp,proximity-close-hysteresis:
+    $ref: /schemas/types.yaml#/definitions/uint8
+    description: |
+      Hysteresis setting for "close" object detection, this setting is
+      device-unique and adjust the optical setting for proximity detection
+      of a "close" object in front of the sensor.
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - sharp,proximity-far-hysteresis
+  - sharp,proximity-close-hysteresis
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      light-sensor@44 {
+        compatible = "sharp,gp2ap002a00f";
+        reg = <0x44>;
+        interrupts = <18 IRQ_TYPE_EDGE_FALLING>;
+        vdd-supply = <&vdd_regulator>;
+        vio-supply = <&vio_regulator>;
+        io-channels = <&adc_channel>;
+        io-channel-names = "alsout";
+        sharp,proximity-far-hysteresis = /bits/ 8 <0x2f>;
+        sharp,proximity-close-hysteresis = /bits/ 8 <0x0f>;
+      };
+    };
+
+...