From: Jens Glathe <jens.glathe@xxxxxxxxxxxxxxxxxxxxxx> 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). Based on a patch by Johan Hovold. [1] Link: https://lore.kernel.org/all/20250120144152.11949-7-johan+linaro@xxxxxxxxxx/ # [1] Signed-off-by: Jens Glathe <jens.glathe@xxxxxxxxxxxxxxxxxxxxxx> --- This is a patch to switch the Windows Dev Kit 2023 over to using the UEFI offset. --- arch/arm64/boot/dts/qcom/sc8280xp-microsoft-blackrock.dts | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-) diff --git a/arch/arm64/boot/dts/qcom/sc8280xp-microsoft-blackrock.dts b/arch/arm64/boot/dts/qcom/sc8280xp-microsoft-blackrock.dts index fa9d941050522..aaea2fa3c6c0a 100644 --- a/arch/arm64/boot/dts/qcom/sc8280xp-microsoft-blackrock.dts +++ b/arch/arm64/boot/dts/qcom/sc8280xp-microsoft-blackrock.dts @@ -762,20 +762,11 @@ &pmk8280_pon_resin { }; &pmk8280_rtc { - nvmem-cells = <&rtc_offset>; - nvmem-cell-names = "offset"; + qcom,uefi-rtc-info; status = "okay"; }; -&pmk8280_sdam_6 { - status = "okay"; - - rtc_offset: rtc-offset@bc { - reg = <0xbc 0x4>; - }; -}; - &pmk8280_vadc { channel@144 { reg = <PM8350_ADC7_AMUX_THM1_100K_PU(1)>; --- base-commit: 232f121837ad8b1c21cc80f2c8842a4090c5a2a0 change-id: 20250120-jg-blackrock-rtc-b4917e6bce94 Best regards, -- Jens Glathe <jens.glathe@xxxxxxxxxxxxxxxxxxxxxx>
