Re: [PATCH v14 0/6] power: reset: Introduce the Power State Change Reasons Recording (PSCRR) framework

[Faruque Ansari <faruque.ansari@oss.qualcomm.com>]

Hi Bradley Morgan,

On 22-Sep-26 12:03 PM, Bradley Morgan wrote:
> On 21 September 2026 18:44:15 BST, Faruque Ansari
> <faruque.ansari@oss.qualcomm.com> wrote:
>> Hello all,
>>
>> A system power-state transition - a shutdown or a reboot - rarely has a
>> single, unambiguous cause, and no one component sees the whole picture:
>> the
>> PMIC, the watchdog, the SoC reset registers, the bootloader and software
>> each
>> only know their own part, so there is no single source of truth.
>>
>> PSCRR gives these sources one central place to report side by side. Every
>> provider keeps its own view - several providers, and several reasons
>> within a
>> provider, can be reported at once and are deliberately not collapsed into
>> a
>> single "winning" cause (a bit of a minority report). On top of that it
>> adds a
>> software-backed recorder, so software-detected reasons - under-voltage,
>> over-temperature, a watchdog pretimeout, a panic, a controlled reboot -
>> are
>> captured too and survive into the next boot.
>>
>> The NVMEM-cell binding a recorder needs to pick its storage is still
>> deadlocked, and several projects already need the framework, so this v13
>> posts the framework, its reboot/reason infrastructure and the sysfs
>> documentation only; the provider drivers (NVMEM, PMIC, ...) and the tests
>> follow separately once the binding is resolved. One built-in provider,
>> reporting the bootloader's device-tree /chosen/reset-source, is kept so
>> the
>> framework is useful on its own without a new binding.
>>
>> For followup drivers, see:
>> https://github.com/olerem/linux-2.6/tree/v7.2/topic/pscr-v12
>>
>> Changes in v14:
>> - Ignore v13, it was mistakenly posted as a reply to Oleksij's v12
>>   patch series.
>>
>> Changes in v13:
>> - Rework pscrr_provider_register() based on review feedback from Francesco Valla:
>>   move the pscrr_root check before allocation and narrow pscrr_lock scope.
>> - Carry the series forward with Faruque Ansari as author and Oleksij
>>   Rempel as co-developer, and vice versa where required.
>> - Link to v12: https://lore.kernel.org/r/20260731095959.296056-1-o.rempel@pengutronix.de
>>
>> Changes in v12:
>> - Drop all provider drivers and their tests; post the framework alone. The
>>   NVMEM-cell binding a recorder needs to pick its storage is still
>>   deadlocked, and several projects already need the framework - so unblock
>>   the core now and let the providers (NVMEM, PMIC, ...) follow separately.
>> - Rework into a multi-provider design (per-provider /sys/kernel/pscrr/
>>   directories); add reason tokens and a built-in /chosen/reset-source
>>   provider.
>>
>> Changes in v11:
>> - add missing break reported by kernel test robot <lkp@intel.com>
>>
>> Changes in v10:
>> - add some add Reviewed-by tags
>> - regulator_handle_critical: set pscr = PSCR_UNKNOWN for default case
>> - make g_pscrr static
>>
>> Changes in v9:
>> - Remove redundant pr_crit() messages before hw_protection_trigger()
>> - Replace psc_reason_to_str() switch with static const string array
>> - Mark psc_last_reason as static
>>
>> Changes in v8:
>> - Use DEFINE_GUARD() and guard(g_pscrr) for scoped locking of the global
>>   pscrr_core struct
>> - Replace manual mutex_lock/unlock with automatic cleanup-based guard() usage
>> - Centralize backend and locking state in struct pscrr_core
>> - Prepare for future multi-backend support with clean encapsulation
>> - Improve sysfs documentation
>>
>> Changes in v7:
>> - document expected values in sysfs documentation
>> - make write support optional
>>
>> Changes in v6:
>> - add sysfs documentation
>> - push core part of the reset reason into kernel/reboot.c
>>
>> Changes in v5:
>> - fix compile with NVMEM=n and potential issues with NVMEM=m
>>
>> Changes in v4:
>> - fix compile with CONFIG_PSCRR=n
>>
>> Changes in v3:
>> - rework to remove devicetree dependencies
>> - extend NVMEM to search devices and cells by names
>>
>> Changes in v2:
>> - rename the framework from PSCR to PSCRR (last R is for Recorder)
>> - extend the power-on reason header and reuse it for the detected reason
>> - rebase on top of v6.8-rc1
> 
> Hey, I dont see the use to PSCRR, are you planning to ship any providers?

I have already posted the NVMEM cell provider support as a 
separate email thread.

https://lore.kernel.org/all/20260914-pscrr-provider-v3-0-c45cb16542e8@oss.qualcomm.com/

Thanks,
Faruque Ansari


>>
>> Signed-off-by: Faruque Ansari <faruque.ansari@oss.qualcomm.com>
>> ---
>> Faruque Ansari (6):
>>       power: Extend power_on_reason.h for upcoming PSCRR framework
>>       reboot: hw_protection_trigger: use standardized numeric shutdown/reboot reasons instead of strings
>>       reboot: add parsable tokens for power state change reasons
>>       reboot: extend psc_reason with power-on and reset causes
>>       power: reset: Introduce PSCR Recording Framework for Non-Volatile Storage
>>       Documentation: Add sysfs documentation for PSCRR
>>
>> Documentation/ABI/testing/sysfs-kernel-pscrr | 108 +++++
>> MAINTAINERS                                  |  11 +
>> drivers/platform/chrome/cros_ec_lpc.c        |   2 +-
>> drivers/power/reset/Kconfig                  |   2 +
>> drivers/power/reset/Makefile                 |   1 +
>> drivers/power/reset/pscrr/Kconfig            |  33 ++
>> drivers/power/reset/pscrr/Makefile           |   2 +
>> drivers/power/reset/pscrr/pscrr.c            | 633
>> +++++++++++++++++++++++++++
>> drivers/regulator/core.c                     |  16 +-
>> drivers/regulator/irq_helpers.c              |   9 +-
>> drivers/thermal/thermal_core.c               |   3 +-
>> include/linux/power/power_on_reason.h        |   5 +
>> include/linux/pscrr.h                        | 107 +++++
>> include/linux/reboot.h                       | 108 ++++-
>> kernel/reboot.c                              | 165 ++++++-
>> 15 files changed, 1183 insertions(+), 22 deletions(-)
>> ---
>> base-commit: 5c4d4169604b335c38bbc79bc1fc03042981fc6f
>> change-id: 20260921-pscrr-framework-25f48818efe8
>>
>> Best regards,
>>
> 
> --- Thanks!
> "I'm not a very positive person" - Linus torvalds