dt-bindings: hwmon: (ina3221) Add ti,single-shot property

By default, ina3221, as a hardware monitor, continuously measures
the inputs and generates corresponding data. However, for battery
powered devices, this mode might be power consuming.

This patch adds a "ti,single-shot" property to allow changing the
default continuous mode to single-shot operating mode.
Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/devicetree/bindings/hwmon/ina3221.txt

@@ -6,6 +6,16 @@ Texas Instruments INA3221 Device Tree Bindings
   - reg: I2C address
 
   Optional properties:
+  - ti,single-shot: This chip has two power modes: single-shot (chip takes one
+                    measurement and then shuts itself down) and continuous (
+                    chip takes continuous measurements). The continuous mode is
+                    more reliable and suitable for hardware monitor type device,
+                    but the single-shot mode is more power-friendly and useful
+                    for battery-powered device which cares power consumptions
+                    while still needs some measurements occasionally.
+                    If this property is present, the single-shot mode will be
+                    used, instead of the default continuous one for monitoring.
+
   = The node contains optional child nodes for three channels =
   = Each child node describes the information of input source =