dt: bindings: update rpi-rtc binding

Add property for bcm2712 firmware RTC driver charger control

Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>

diff --git a/Documentation/devicetree/bindings/rtc/rtc-rpi.txt b/Documentation/devicetree/bindings/rtc/rtc-rpi.txt
index bbbc28b..ed0d0d0 100644 (file)
--- a/Documentation/devicetree/bindings/rtc/rtc-rpi.txt
+++ b/Documentation/devicetree/bindings/rtc/rtc-rpi.txt
@@ -9,9 +9,14 @@ Required properties:
 compatible: should be "raspberrypi,rpi-rtc"
 firmware:   Reference to the RPi firmware device node.
 
+Optional property:
+trickle-charge-microvolt: specify a trickle charge voltage for the backup
+                          battery in microvolts.
+
 Example:
 
        rpi_rtc: rpi_rtc {
                compatible = "raspberrypi,rpi-rtc";
                firmware = <&firmware>;
+               trickle-charge-microvolt = <3000000>;
        };