dt-bindings: power: Add the bq256xx dt bindings

Add the bindings for the bq256xx series of battery charging ICs.

Datasheets:
- https://www.ti.com/lit/ds/symlink/bq25600.pdf
- https://www.ti.com/lit/ds/symlink/bq25601.pdf
- https://www.ti.com/lit/ds/symlink/bq25600d.pdf
- https://www.ti.com/lit/ds/symlink/bq25601d.pdf
- https://www.ti.com/lit/ds/symlink/bq25611d.pdf
- https://www.ti.com/lit/ds/symlink/bq25618.pdf
- https://www.ti.com/lit/ds/symlink/bq25619.pdfReviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Ricardo Rivera-Matos <r-rivera-matos@ti.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

Documentation/devicetree/bindings/power/supply/bq256xx.yaml

+# SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
+# Copyright (C) 2020 Texas Instruments Incorporated
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/power/supply/bq256xx.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: TI bq256xx Switch Mode Buck Charger
+
+maintainers:
+  - Ricardo Rivera-Matos <r-rivera-matos@ti.com>
+
+description: |
+  The bq256xx devices are a family of highly-integrated battery charge
+  management and system power management ICs for single cell Li-ion and Li-
+  polymer batteries.
+
+  Datasheets:
+    - https://www.ti.com/lit/ds/symlink/bq25600.pdf
+    - https://www.ti.com/lit/ds/symlink/bq25601.pdf
+    - https://www.ti.com/lit/ds/symlink/bq25600d.pdf
+    - https://www.ti.com/lit/ds/symlink/bq25601d.pdf
+    - https://www.ti.com/lit/ds/symlink/bq25611d.pdf
+    - https://www.ti.com/lit/ds/symlink/bq25618.pdf
+    - https://www.ti.com/lit/ds/symlink/bq25619.pdf
+
+properties:
+  compatible:
+    enum:
+      - ti,bq25600
+      - ti,bq25601
+      - ti,bq25600d
+      - ti,bq25601d
+      - ti,bq25611d
+      - ti,bq25618
+      - ti,bq25619
+
+  reg:
+    maxItems: 1
+
+  ti,watchdog-timeout-ms:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    default: 0
+    description: |
+      Watchdog timer in ms. 0 (default) disables the watchdog
+    minimum: 0
+    maximum: 160000
+    enum: [ 0, 40000, 80000, 160000]
+
+  input-voltage-limit-microvolt:
+    description: |
+       Minimum input voltage limit in µV with a 100000 µV step
+    minimum: 3900000
+    maximum: 5400000
+
+  input-current-limit-microamp:
+    description: |
+       Maximum input current limit in µA with a 100000 µA step
+    minimum: 100000
+    maximum: 3200000
+
+  monitored-battery:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description: phandle to the battery node being monitored
+
+  interrupts:
+    maxItems: 1
+    description: |
+      Interrupt sends an active low, 256 μs pulse to host to report the charger
+      device status and faults.
+
+required:
+  - compatible
+  - reg
+  - monitored-battery
+
+additionalProperties: false
+
+examples:
+  - |
+    bat: battery {
+      compatible = "simple-battery";
+      constant-charge-current-max-microamp = <2040000>;
+      constant-charge-voltage-max-microvolt = <4352000>;
+      precharge-current-microamp = <180000>;
+      charge-term-current-microamp = <180000>;
+    };
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    i2c {
+
+      clock-frequency = <400000>;
+
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      charger@6b {
+        compatible = "ti,bq25601";
+        reg = <0x6b>;
+        monitored-battery = <&bat>;
+
+        interrupt-parent = <&gpio1>;
+        interrupts = <16 IRQ_TYPE_EDGE_FALLING>;
+        ti,watchdog-timeout-ms = <40000>;
+
+        input-voltage-limit-microvolt = <4500000>;
+        input-current-limit-microamp = <2400000>;
+       };
+    };
+...