mfd: dt: Add bindings for DA9063 OnKey

Add device tree bindings for the DA9063 OnKey driver.
Signed-off-by: NSteve Twiss <stwiss.opensource@diasemi.com>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NLee Jones <lee.jones@linaro.org>

Documentation/devicetree/bindings/mfd/da9063.txt

@@ -5,6 +5,7 @@ DA9093 consists of a large and varied group of sub-devices (I2C Only):
 Device                   Supply Names    Description
 ------                   ------------    -----------
 da9063-regulator        :               : LDOs & BUCKs
+da9063-onkey            :               : On Key
 da9063-rtc              :               : Real-Time Clock
 da9063-watchdog         :               : Watchdog
 
@@ -51,6 +52,18 @@ Sub-nodes:
   the DA9063. There are currently no entries in this binding, however
   compatible = "dlg,da9063-rtc" should be added if a node is created.
 
+- onkey : This node defines the OnKey settings for controlling the key
+  functionality of the device. The node should contain the compatible property
+  with the value "dlg,da9063-onkey".
+
+  Optional onkey properties:
+
+  - dlg,disable-key-power : Disable power-down using a long key-press. If this
+    entry exists the OnKey driver will remove support for the KEY_POWER key
+    press. If this entry does not exist then by default the key-press
+    triggered power down is enabled and the OnKey will support both KEY_POWER
+    and KEY_SLEEP.
+
 - watchdog : This node defines settings for the Watchdog timer associated
   with the DA9063. There are currently no entries in this binding, however
   compatible = "dlg,da9063-watchdog" should be added if a node is created.
@@ -73,6 +86,11 @@ Example:
 			compatible = "dlg,da9063-watchdog";
 		};
 
+		onkey {
+			compatible = "dlg,da9063-onkey";
+			dlg,disable-key-power;
+		};
+
 		regulators {
 			DA9063_BCORE1: bcore1 {
 				regulator-name = "BCORE1";