rtc: bq32000: add trickle charger device tree binding

BQ32000 have "trickle chargers".  Introduce a device tree binding for
specifying the trickle charger configuration for that.

Signed-off-by: Pavel Machek <[email protected]>
Reviewed-by: Jason Cooper <[email protected]>
Cc: Matti Vaittinen <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Ian Campbell <[email protected]>
Cc: Alessandro Zummo <[email protected]>
Cc: Guenter Roeck <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Documentation/devicetree/bindings/i2c/ti,bq32k.txt

@@ -0,0 +1,18 @@
+* TI BQ32000                I2C Serial Real-Time Clock
+
+Required properties:
+- compatible: Should contain "ti,bq32000".
+- reg: I2C address for chip
+
+Optional properties:
+- trickle-resistor-ohms : Selected resistor for trickle charger
+       Values usable are 1120 and 20180
+       Should be given if trickle charger should be enabled
+- trickle-diode-disable : Do not use internal trickle charger diode
+       Should be given if internal trickle charger diode should be disabled
+Example:
+       bq32000: rtc@68 {
+               compatible = "ti,bq32000";
+               trickle-resistor-ohms = <1120>;
+               reg = <0x68>;
+       };