dt-bindings: power: Introduce properties to present the battery OCV capacity table

Some battery driver will use the open circuit voltage (OCV) value to look
up the corresponding battery capacity percent in one certain degree Celsius.
Thus this patch provides some battery properties to present the OCV table
temperatures and OCV capacity table values.
Suggested-by: NSebastian Reichel <sre@kernel.org>
Signed-off-by: NBaolin Wang <baolin.wang@linaro.org>
Reviewed-by: NLinus Walleij <linus.walleij@linaro.org>
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NSebastian Reichel <sebastian.reichel@collabora.com>

Documentation/devicetree/bindings/power/supply/battery.txt

@@ -23,6 +23,17 @@ Optional Properties:
  - constant-charge-current-max-microamp: maximum constant input current
  - constant-charge-voltage-max-microvolt: maximum constant input voltage
  - factory-internal-resistance-micro-ohms: battery factory internal resistance
+ - ocv-capacity-table-0: An array providing the open circuit voltage (OCV)
+   of the battery and corresponding battery capacity percent, which is used
+   to look up battery capacity according to current OCV value. And the open
+   circuit voltage unit is microvolt.
+ - ocv-capacity-table-1: Same as ocv-capacity-table-0
+ ......
+ - ocv-capacity-table-n: Same as ocv-capacity-table-0
+ - ocv-capacity-celsius: An array containing the temperature in degree Celsius,
+   for each of the battery capacity lookup table. The first temperature value
+   specifies the OCV table 0, and the second temperature value specifies the
+   OCV table 1, and so on.
 
 Battery properties are named, where possible, for the corresponding
 elements in enum power_supply_property, defined in
@@ -44,6 +55,10 @@ Example:
 		constant-charge-current-max-microamp = <900000>;
 		constant-charge-voltage-max-microvolt = <4200000>;
 		factory-internal-resistance-micro-ohms = <250000>;
+		ocv-capacity-celsius = <(-10) 0 10>;
+		ocv-capacity-table-0 = <4185000 100>, <4113000 95>, <4066000 90>, ...;
+		ocv-capacity-table-1 = <4200000 100>, <4185000 95>, <4113000 90>, ...;
+		ocv-capacity-table-2 = <4250000 100>, <4200000 95>, <4185000 90>, ...;
 	};
 
 	charger: charger@11 {