[RFC 18/24] dt-bindings: rtc: qcom-pm8xxx: add uefi-variable offset

[Johan Hovold]

On many Qualcomm platforms the PMIC RTC control and time registers are
read-only so that the RTC time can not be updated. Instead an offset
needs be stored in some machine-specific non-volatile memory, which a
driver can take into account.

Add a 'qcom,uefi-rtc-info' boolean flag which indicates that the RTC
offset is stored in a Qualcomm specific UEFI variable so that the RTC
time can be updated on such platforms.

The UEFI variable is

	882f8c2b-9646-435f-8de5-f208ff80c1bd-RTCInfo

and holds a 12-byte structure where the first four bytes is a GPS time
offset in little-endian byte order.

Signed-off-by: Johan Hovold <johan+linaro@xxxxxxxxxx>
---
 Documentation/devicetree/bindings/rtc/qcom-pm8xxx-rtc.yaml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/rtc/qcom-pm8xxx-rtc.yaml b/Documentation/devicetree/bindings/rtc/qcom-pm8xxx-rtc.yaml
index b95a69cc9ae0..774c34c3f8f6 100644
--- a/Documentation/devicetree/bindings/rtc/qcom-pm8xxx-rtc.yaml
+++ b/Documentation/devicetree/bindings/rtc/qcom-pm8xxx-rtc.yaml
@@ -50,6 +50,12 @@ properties:
     items:
       - const: offset
 
+  qcom,uefi-rtc-info:
+    type: boolean
+    description:
+      RTC offset is stored as a four-byte GPS time offset in a 12-byte UEFI
+      variable 882f8c2b-9646-435f-8de5-f208ff80c1bd-RTCInfo
+
   wakeup-source: true
 
 required:
-- 
2.39.1