The ST M41T80 family of RTC are not trivial devices, document them.
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Rob Herring <robh@kernel.org>
--- /dev/null
+ST M41T80 family of RTC and compatible
+
+Required properties:
+- compatible: should be one of:
+       "st,m41t62",
+       "st,m41t65",
+       "st,m41t80",
+       "st,m41t81",
+       "st,m41t81s",
+       "st,m41t82",
+       "st,m41t83",
+       "st,m41t84",
+       "st,m41t85",
+       "st,m41t87",
+       "microcrystal,rv4162",
+- reg: I2C bus address of the device
+
+Optional properties:
+- interrupt-parent: phandle for the interrupt controller.
+- interrupts: rtc alarm interrupt.
+- clock-output-names: From common clock binding to override the default output
+                      clock name
+- wakeup-source: Enables wake up of host system on alarm
+
+Example:
+       rtc@68 {
+               compatible = "st,m41t80";
+               reg = <0x68>;
+               interrupt-parent = <&UIC0>;
+               interrupts = <0x9 0x8>;
+       };
 
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