Add a binding for the regulator which controls the OTG chargepath switch.
The OTG switch gets its power from pm8941_5vs1, and that should be
expressed as a usb-otg-in-supply property in the DT node for the
charger driver.  The regulator name is "otg".

Signed-off-by: Tim Bird <redacted>
---
Changes since v1
 - switch supply name to have dashes instead of underscores
 - remove superfluous DT explanations in the otg node description
---
 .../devicetree/bindings/power_supply/qcom_smbb.txt    | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/Documentation/devicetree/bindings/power_supply/qcom_smbb.txt b/Documentation/devicetree/bindings/power_supply/qcom_smbb.txt
index 65b88fa..28b6da7 100644
--- a/Documentation/devicetree/bindings/power_supply/qcom_smbb.txt
+++ b/Documentation/devicetree/bindings/power_supply/qcom_smbb.txt

@@ -105,6 +105,22 @@ PROPERTIES
                regulation must be done externally to fully comply with
                the JEITA safety guidelines if this flag is set.
 
+- usb-otg-in-supply:
+  Usage: optional
+  Value type: <phandle>
+  Description: Reference to the regulator supplying power to the USB_OTG_IN
+               pin.
+
+child nodes:
+- otg:
+  Usage: optional
+  Description: This node defines a regulator used to control the direction
+               of VBUS voltage - specifically: whether to supply voltage
+               to VBUS for host mode operation of the OTG port, or allow
+               input voltage from external VBUS for charging.  In the
+               hardware, the supply for this regulator comes from
+               usb-otg-in-supply.