From: Jens Glathe <jens.glathe@oldschoolsolutions.biz>

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@kernel.org/ # [1]
Signed-off-by: Jens Glathe <jens.glathe@oldschoolsolutions.biz>
---
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@oldschoolsolutions.biz>

Hi Jens,

On Wed, Jan 22, 2025 at 07:41:56AM +0100, Jens Glathe via B4 Relay wrote:
> From: Jens Glathe <jens.glathe@oldschoolsolutions.biz>
> 
> 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@kernel.org/ # [1]
> Signed-off-by: Jens Glathe <jens.glathe@oldschoolsolutions.biz>
> ---
> This is a patch to switch the Windows Dev Kit 2023 over to
> using the UEFI offset.

Please try to avoid posting patches before their dependencies have been
merged, but at least mention any such dependencies in the cover letter
(or here under the --- line).

The series this patch depends on has now been superseded with a v2
dropping the DT property so this one will also need a respin once the
driver changes have been merged:

	https://lore.kernel.org/all/20250219134118.31017-1-johan+linaro@kernel.org/

Johan

On 22.01.2025 7:41 AM, Jens Glathe via B4 Relay wrote:
> From: Jens Glathe <jens.glathe@oldschoolsolutions.biz>
> 
> 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@kernel.org/ # [1]
> Signed-off-by: Jens Glathe <jens.glathe@oldschoolsolutions.biz>
> ---

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

Konrad

On Wed, 22 Jan 2025 07:41:56 +0100, Jens Glathe wrote:
> 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@kernel.org/ # [1]
> Signed-off-by: Jens Glathe <jens.glathe@oldschoolsolutions.biz>
> ---
> 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(-)
> 


My bot found new DTB warnings on the .dts files added or changed in this
series.

Some warnings may be from an existing SoC .dtsi. Or perhaps the warnings
are fixed by another series. Ultimately, it is up to the platform
maintainer whether these warnings are acceptable or not. No need to reply
unless the platform maintainer has comments.

If you already ran DT checks and didn't see these error(s), then
make sure dt-schema is up to date:

  pip3 install dtschema --upgrade


New warnings running 'make CHECK_DTBS=y for arch/arm64/boot/dts/qcom/' for 20250122-jg-blackrock-rtc-v1-1-3b05cd85bdfa@oldschoolsolutions.biz:

arch/arm64/boot/dts/qcom/sc8280xp-microsoft-blackrock.dtb: pmic@0: rtc@6100: 'qcom,uefi-rtc-info' does not match any of the regexes: 'pinctrl-[0-9]+'
	from schema $id: http://devicetree.org/schemas/mfd/qcom,spmi-pmic.yaml#
arch/arm64/boot/dts/qcom/sc8280xp-microsoft-blackrock.dtb: rtc@6100: 'qcom,uefi-rtc-info' does not match any of the regexes: 'pinctrl-[0-9]+'
	from schema $id: http://devicetree.org/schemas/rtc/qcom-pm8xxx-rtc.yaml#