linux-kernel - [PATCH v2 5/6] arm64: dts: qcom: sc8280xp-x13s: switch to uefi rtc offset

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Message-ID: <20250219134118.31017-6-johan+linaro@kernel.org>
Date: Wed, 19 Feb 2025 14:41:17 +0100
From: Johan Hovold <johan+linaro@...nel.org>
To: Alexandre Belloni <alexandre.belloni@...tlin.com>,
	Bjorn Andersson <andersson@...nel.org>
Cc: Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Konrad Dybcio <konradybcio@...nel.org>,
	Jonathan Marek <jonathan@...ek.ca>,
	Ard Biesheuvel <ardb@...nel.org>,
	Maximilian Luz <luzmaximilian@...il.com>,
	Jens Glathe <jens.glathe@...schoolsolutions.biz>,
	Joel Stanley <joel@....id.au>,
	Sebastian Reichel <sre@...nel.org>,
	Steev Klimaszewski <steev@...i.org>,
	linux-arm-msm@...r.kernel.org,
	linux-rtc@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Johan Hovold <johan+linaro@...nel.org>,
	Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Subject: [PATCH v2 5/6] arm64: dts: qcom: sc8280xp-x13s: switch to uefi rtc offset

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.

Switch to using the Qualcomm specific UEFI variable that is used by the
UEFI firmware (and Windows) to store the RTC offset.

This specifically means that the RTC time will be synchronised between
the UEFI firmware setup (or UEFI shell), Windows and Linux.

Note however that Windows stores the RTC time in local time by default,
while Linux typically uses UTC (i.e. as on X86).

Tested-by: Jens Glathe <jens.glathe@...schoolsolutions.biz>
Tested-by: Steev Klimaszewski <steev@...i.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Signed-off-by: Johan Hovold <johan+linaro@...nel.org>
---
 .../boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts   | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts b/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts
index 38d911992475..8000254f4db5 100644
--- a/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts
+++ b/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts
@@ -1090,18 +1090,7 @@ &pmk8280_pon_resin {
 };
 
 &pmk8280_rtc {
-	nvmem-cells = <&rtc_offset>;
-	nvmem-cell-names = "offset";
-
-	status = "okay";
-};
-
-&pmk8280_sdam_6 {
 	status = "okay";
-
-	rtc_offset: rtc-offset@bc {
-		reg = <0xbc 0x4>;
-	};
 };
 
 &pmk8280_vadc {
-- 
2.45.3