On Tue, May 10, 2022 at 1:33 AM Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx> wrote: > > Problem > ------- > > SoC devices require power-off call chaining functionality from kernel. > We have a widely used restart chaining provided by restart notifier API, > but nothing for power-off. > > Solution > -------- > > Introduce new API that provides call chains support for all restart and > power-off modes. The new API is designed with simplicity and extensibility > in mind. > > This is a third attempt to introduce the new API. First was made by > Guenter Roeck back in 2014, second was made by Thierry Reding in 2017. > In fact the work didn't stop and recently arm_pm_restart() was removed > from v5.14 kernel, which was a part of preparatory work started by > Guenter Roeck. > > Adoption plan > ------------- > > This patchset introduces the new API. It also converts multiple drivers > and arch code to the new API to demonstrate how it all looks in practice, > removing the pm_power_off_prepare global variable. > > The plan is: > > 1. Merge the new API and convert arch code to use do_kernel_power_off(). > For now the new API will co-exist with the older API. > > 2. Convert all drivers and platform code to the new API. > > 3. Remove obsoleted pm_power_off and pm_power_off_prepare variables. > > Results > ------- > > 1. Devices can be powered off properly. > > 2. Global variables are removed from drivers. > > 3. Global pm_power_off and pm_power_off_prepare callback variables are > removed once all users are converted to the new API. The latter callback > is removed by patch #24 of this series. > > 4. Ambiguous call chain ordering is prohibited for non-default priorities. > > Changelog: > > v8: - Reworked sys-off handler like was suggested by Rafael Wysocki in > the comments to v7. > > - The struct sys-off handler now is private to kernel/reboot.c and > new API is simplified. > > - There is a single sys-off API function for all handler types. > Users shall pass the required sys-off mode type (restart, power-off > and etc). > > - There is single struct sys_off_data callback argument for all > handler modes. > > - User's callback now must return NOTIFY_DONE or NOTIFY_STOP. > > - The default priority level is zero now. > > - Multiple handlers now allowed to be registered at the default > priority level. > > - Power-off call chain is atomic now, like the restart chain. > > - kernel/reboot.c changes are split up into several logical patches. > > - Added r-b from Michał Mirosław to unmodified patches from v7. > > - Added acks that were missing in v7 by accident. The v8 looks much better than the previous versions to me. I actually don't really have any comments on it except for the minor remark regarding patch [1/27] sent separately. Please just send an update of that one patch and I will queue up the series for 5.19. However, I'm going to send a pull request with it in the second half of the merge window, after the majority of the other changes in the subsystems touched by it have been integrated. > v7: - Rebased on a recent linux-next. Dropped the recently removed > NDS32 architecture. Only SH and x86 arches left un-acked. > > - Added acks from Thomas Bogendoerfer and Krzysztof Kozlowski > to the MIPS and memory/emif patches respectively. > > - Made couple minor cosmetic improvements to the new API. > > - A month ago I joined Collabora and continuing to work on this series > on the company's time, so changed my email address to collabora.com > > v6: - Rebased on a recent linux-next. > > - Made minor couple cosmetic changes. > > v5: - Dropped patches which cleaned up notifier/reboot headers, as was > requested by Rafael Wysocki. > > - Dropped WARN_ON() from the code, as was requested by Rafael Wysocki. > Replaced it with pr_err() appropriately. > > - Dropped *_notifier_has_unique_priority() functions and added > *_notifier_chain_register_unique_prio() instead, as was suggested > by Michał Mirosław and Rafael Wysocki. > > - Dropped export of blocking_notifier_call_chain_is_empty() symbol, > as was suggested by Rafael Wysocki. > > - Michał Mirosław suggested that will be better to split up patch > that adds the new API to ease reviewing, but Rafael Wysocki asked > not add more patches, so I kept it as a single patch. > > - Added temporary "weak" stub for pm_power_off() which fixes linkage > failure once symbol is removed from arch/* code. Previously I missed > this problem because was only compile-testing object files. > > v4: - Made a very minor improvement to doc comments, clarifying couple > default values. > > - Corrected list of emails recipient by adding Linus, Sebastian, > Philipp and more NDS people. Removed bouncing emails. > > - Added acks that were given to v3. > > v3: - Renamed power_handler to sys_off_handler as was suggested by > Rafael Wysocki. > > - Improved doc-comments as was suggested by Rafael Wysocki. Added more > doc-comments. > > - Implemented full set of 180 patches which convert whole kernel in > accordance to the plan, see link [1] above. Slightly adjusted API to > better suit for the remaining converted drivers. > > * Added unregister_sys_off_handler() that is handy for a couple old > platform drivers. > > * Dropped devm_register_trivial_restart_handler(), 'simple' variant > is enough to have. > > - Improved "Add atomic/blocking_notifier_has_unique_priority()" patch, > as was suggested by Andy Shevchenko. Also replaced down_write() with > down_read() and factored out common notifier_has_unique_priority(). > > - Added stop_chain field to struct restart_data and reboot_prep_data > after discovering couple drivers wanting that feature. > > - Added acks that were given to v2. > > v2: - Replaced standalone power-off call chain demo-API with the combined > power-off+restart API because this is what drivers want. It's a more > comprehensive solution. > > - Converted multiple drivers and arch code to the new API. Suggested by > Andy Shevchenko. I skimmed through the rest of drivers, verifying that > new API suits them. The rest of the drivers will be converted once we > will settle on the new API, otherwise will be too many patches here. > > - v2 API doesn't expose notifier to users and require handlers to > have unique priority. Suggested by Guenter Roeck. > > - v2 API has power-off chaining disabled by default and require > drivers to explicitly opt-in to the chaining. This preserves old > behaviour for existing drivers once they are converted to the new > API. > > Dmitry Osipenko (27): > notifier: Add atomic_notifier_call_chain_is_empty() > notifier: Add blocking/atomic_notifier_chain_register_unique_prio() > kernel/reboot: Introduce sys-off handler API > kernel/reboot: Wrap legacy power-off callbacks into sys-off handlers > kernel/reboot: Add do_kernel_power_off() > kernel/reboot: Add stub for pm_power_off > kernel/reboot: Add kernel_can_power_off() > kernel/reboot: Add register_platform_power_off() > ARM: Use do_kernel_power_off() > csky: Use do_kernel_power_off() > riscv: Use do_kernel_power_off() > arm64: Use do_kernel_power_off() > parisc: Use do_kernel_power_off() > xen/x86: Use do_kernel_power_off() > powerpc: Use do_kernel_power_off() > m68k: Switch to new sys-off handler API > sh: Use do_kernel_power_off() > x86: Use do_kernel_power_off() > ia64: Use do_kernel_power_off() > mips: Use do_kernel_power_off() > memory: emif: Use kernel_can_power_off() > ACPI: power: Switch to sys-off handler API > regulator: pfuze100: Use devm_register_sys_off_handler() > reboot: Remove pm_power_off_prepare() > soc/tegra: pmc: Use sys-off handler API to power off Nexus 7 properly > kernel/reboot: Add devm_register_power_off_handler() > kernel/reboot: Add devm_register_restart_handler() > > arch/arm/kernel/reboot.c | 4 +- > arch/arm64/kernel/process.c | 3 +- > arch/csky/kernel/power.c | 6 +- > arch/ia64/kernel/process.c | 4 +- > arch/m68k/emu/natfeat.c | 3 +- > arch/m68k/include/asm/machdep.h | 1 - > arch/m68k/kernel/process.c | 5 +- > arch/m68k/kernel/setup_mm.c | 1 - > arch/m68k/kernel/setup_no.c | 1 - > arch/m68k/mac/config.c | 4 +- > arch/mips/kernel/reset.c | 3 +- > arch/parisc/kernel/process.c | 4 +- > arch/powerpc/kernel/setup-common.c | 4 +- > arch/powerpc/xmon/xmon.c | 3 +- > arch/riscv/kernel/reset.c | 12 +- > arch/sh/kernel/reboot.c | 3 +- > arch/x86/kernel/reboot.c | 4 +- > arch/x86/xen/enlighten_pv.c | 4 +- > drivers/acpi/sleep.c | 16 +- > drivers/memory/emif.c | 2 +- > drivers/regulator/pfuze100-regulator.c | 42 ++- > drivers/soc/tegra/pmc.c | 87 +++++-- > include/linux/notifier.h | 7 + > include/linux/pm.h | 1 - > include/linux/reboot.h | 91 +++++++ > kernel/notifier.c | 101 +++++-- > kernel/reboot.c | 347 ++++++++++++++++++++++++- > 27 files changed, 639 insertions(+), 124 deletions(-) > > -- > 2.35.1 >
