dt-bindings: mfd: Add Rockchip rk817 battery charger support

Create dt-binding documentation to document rk817 battery and charger
usage. New device-tree properties have been added.

- rockchip,resistor-sense-micro-ohms: The value in microohms of the
                                      sample resistor.
- rockchip,sleep-enter-current-microamp: The value in microamps of the
                                         sleep enter current.
- rockchip,sleep-filter-current: The value in microamps of the sleep
                                 filter current.

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Signed-off-by: Maya Matuszczyk <maccraft123mc@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20220827021623.23829-2-macroalpha82@gmail.com

Documentation/devicetree/bindings/mfd/rockchip,rk817.yaml

@@ -117,6 +117,49 @@ properties:
         description:
           Describes if the microphone uses differential mode.
 
+  charger:
+    description: |
+      The child node for the charger to hold additional properties. If a
+      battery is not in use, this node can be omitted.
+    type: object
+    properties:
+      monitored-battery:
+        description: |
+          A phandle to a monitored battery node that contains a valid
+          value for:
+          charge-full-design-microamp-hours,
+          charge-term-current-microamp,
+          constant-charge-current-max-microamp,
+          constant-charge-voltage-max-microvolt,
+          voltage-max-design-microvolt,
+          voltage-min-design-microvolt,
+          and a valid ocv-capacity table.
+
+      rockchip,resistor-sense-micro-ohms:
+        description: |
+          Value in microohms of the battery sense resistor. This value is
+          used by the driver to set the correct divisor value to translate
+          ADC readings into the proper units of measure.
+        enum: [10000, 20000]
+
+      rockchip,sleep-enter-current-microamp:
+        description: |
+          Value in microamps of the sleep enter current for the charger.
+          Value is used by the driver to calibrate the relax threshold.
+
+      rockchip,sleep-filter-current-microamp:
+        description:
+          Value in microamps of the sleep filter current for the charger.
+          Value is used by the driver to derive the sleep sample current.
+
+    required:
+      - monitored-battery
+      - rockchip,resistor-sense-micro-ohms
+      - rockchip,sleep-enter-current-microamp
+      - rockchip,sleep-filter-current-microamp
+
+    additionalProperties: false
+
 allOf:
   - if:
       properties:
@@ -323,6 +366,13 @@ examples:
                 };
             };
 
+            rk817_charger: charger {
+                monitored-battery = <&battery>;
+                rockchip,resistor-sense-micro-ohms = <10000>;
+                rockchip,sleep-enter-current-microamp = <300000>;
+                rockchip,sleep-filter-current-microamp = <100000>;
+            };
+
             rk817_codec: codec {
                 rockchip,mic-in-differential;
             };