This series adds support for setting the RTC time on Qualcomm platforms where the PMIC RTC time registers are read-only by instead storing an offset in some other non-volatile memory. This is used to enable the RTC in the SC8280XP Compute Reference Design (CRD) and Lenovo Thinkpad X13s laptop. The RTCs in many Qualcomm devices are effectively broken due to the time registers being read-only. Instead some other non-volatile memory can be used to store and offset which a driver can take into account. On machines like the X13s, the UEFI firmware (and Windows) use a UEFI variable for storing such an offset, but not all Qualcomm systems use UEFI. The Qualcomm firmware also does not support any UEFI runtime services, but Maximilian Luz recently posted a driver for talking to the secure world directly through the SCM interface and this can be used to access the UEFI variables: https://lore.kernel.org/all/20220723224949.1089973-1-luzmaximilian@xxxxxxxxx/ I was initially told that the PMICs in the X13s did not have any spare battery-backed registers which could have been used to store an RTC offset so there seemed to be no alternative to try using the UEFI offset. In the processes however, I learnt that there are in fact some registers in PMIC that could be used, at least on the SC8280XP CRD and the X13s. This was especially fortunate as it turned out that the firmware on the CRD does not allow updating the UEFI RTC offset even if this works on the X13s. As the benefit of sharing the RTC offset with the UEFI firmware (and Windows) is rather small (e.g. to make sure they never get out sync), I instead opted for using the PMIC registers on both machines. This also avoids relying on a fairly complex reverse-engineered firmware driver, as well as potential issues like flash wear due to RTC drift. Let's keep it simple. But as there could be older Qualcomm UEFI machines out there where we don't have any other non-volatile storage I included the UEFI patches here as an RFC for reference. In case it turns out there are systems out there were this could be used, those two patches could be merged as well. An alternative could be to see if Maximilian's work could be extended to access the time services directly. This series first fixes a few issues with the current Qualcomm PMIC RTC driver before cleaning it up a bit so that support for setting the time using an offset stored in an nvmem cell can be added. The two RFC patches on top, add support for the Qualcomm UEFI RTC offset and are not intended to be merged just yet. Note that these two also depend on an efi core patch that has been merged for 6.3: https://lore.kernel.org/all/20230119164255.28091-1-johan+linaro@xxxxxxxxxx/ The final patches enables the RTC on the SC8280XP CRD and X13s and can be merged by Bjorn once the (non-UEFI) RTC patches are in. Note that for the SDAM nvmem driver to be autoloaded when built as a module, you also need this fix: https://lore.kernel.org/lkml/20230126133034.27491-1-johan+linaro@xxxxxxxxxx/ Johan Johan Hovold (24): rtc: pm8xxx: fix set-alarm race rtc: pm8xxx: drop spmi error messages rtc: pm8xxx: use regmap_update_bits() rtc: pm8xxx: drop bogus locking rtc: pm8xxx: return IRQ_NONE on errors rtc: pm8xxx: drop unused register defines rtc: pm8xxx: use unaligned le32 helpers rtc: pm8xxx: clean up time and alarm debugging rtc: pm8xxx: rename struct device pointer rtc: pm8xxx: rename alarm irq variable rtc: pm8xxx: clean up comments rtc: pm8xxx: use u32 for timestamps rtc: pm8xxx: refactor read_time() rtc: pm8xxx: clean up local declarations dt-bindings: rtc: qcom-pm8xxx: add nvmem-cell offset rtc: pm8xxx: add support for nvmem offset rtc: pm8xxx: add copyright notice dt-bindings: rtc: qcom-pm8xxx: add uefi-variable offset rtc: pm8xxx: add support for uefi offset arm64: defconfig: enable Qualcomm SDAM nvmem driver arm64: dts: qcom: sc8280xp-pmics: add pmk8280 rtc arm64: dts: qcom: sc8280xp-pmics: add pmk8280 sdam nvram arm64: dts: qcom: sc8280xp-crd: enable rtc arm64: dts: qcom: sc8280xp-x13s: enable rtc .../bindings/rtc/qcom-pm8xxx-rtc.yaml | 18 + arch/arm64/boot/dts/qcom/sc8280xp-crd.dts | 15 + .../qcom/sc8280xp-lenovo-thinkpad-x13s.dts | 15 + arch/arm64/boot/dts/qcom/sc8280xp-pmics.dtsi | 18 + arch/arm64/configs/defconfig | 1 + drivers/rtc/rtc-pm8xxx.c | 639 ++++++++++-------- include/linux/rtc.h | 1 + 7 files changed, 443 insertions(+), 264 deletions(-) -- 2.39.1
