dt-bindings: rtc: qcom-pm8xxx: document qcom,no-alarm flag

Qualcomm x1e80100 firmware sets the ownership of the RTC alarm to ADSP.
Thus writing to RTC alarm registers and receiving alarm interrupts is not
possible.

Add a qcom,no-alarm flag to support RTC on this platform.

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Link: https://lore.kernel.org/r/20241015004945.3676-3-jonathan@marek.ca
[ johan: move vendor property; use boolean; reword description ]
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20250219134118.31017-2-johan+linaro@kernel.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: flto

Documentation/devicetree/bindings/rtc/qcom-pm8xxx-rtc.yaml

@@ -50,6 +50,11 @@ properties:
     items:
       - const: offset
 
+  qcom,no-alarm:
+    type: boolean
+    description:
+      RTC alarm is not owned by the OS
+
   wakeup-source: true
 
 required: