08.11.2021 03:44, Dmitry Osipenko пишет: > 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 both restart and power-off call chains. > > Why combine restart with power-off? Because drivers often do both. > More practical to have API that provides both under the same roof. > > The new API is designed with simplicity and extensibility in mind. > It's built upon the existing restart and reboot APIs. The simplicity > is in new helper functions that are convenient for drivers. The > extensibility is in the design that doesn't hardcode callback > arguments, making easy to add new parameters and remove old. > > 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. I took into account experience and ideas from the > previous attempts, extended and polished them. > > 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. > > The plan is: > > 1. Merge new API (patches 1-8). This API will co-exist with the old APIs. > > 2. Convert arch code to do_kernel_power_off() (patches 9-21). > > 3. Convert drivers and platform code to the new API. > > 4. Remove obsolete pm_power_off and pm_power_off_prepare variables. > > 5. Make restart-notifier API private to kernel/reboot.c once no users left. > > It's fully implemented here: > > [1] https://github.com/grate-driver/linux/commits/sys-off-handler > > For now I'm sending only the first 25 base patches out of ~180. It's > preferable to squash 1-2, partially 3 and 4 points of the plan into a > single patchset to ease and speed up applying of the rest of the patches. > Majority of drivers and platform patches depend on the base, hence they > will come later (and per subsystem), once base will land. > > All [1] patches are compile-tested. Tegra and x86 ACPI patches are tested > on hardware. The remaining should be covered by unit tests (unpublished). > > 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 #25 of this series. > > 4. Ambiguous call chain ordering is prohibited. See patch #5 which adds > verification of restart handlers priorities, ensuring that they are unique. > > Changelog: > > 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 (25): > notifier: Remove extern annotation from function prototypes > notifier: Add blocking_notifier_call_chain_is_empty() > notifier: Add atomic/blocking_notifier_has_unique_priority() > reboot: Correct typo in a comment > reboot: Warn if restart handler has duplicated priority > reboot: Warn if unregister_restart_handler() fails > reboot: Remove extern annotation from function prototypes > kernel: Add combined power-off+restart handler call chain API > 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() > sh: Use do_kernel_power_off() > x86: Use do_kernel_power_off() > ia64: Use do_kernel_power_off() > mips: Use do_kernel_power_off() > nds32: Use do_kernel_power_off() > powerpc: Use do_kernel_power_off() > m68k: Switch to new sys-off handler API > 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() > > 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/nds32/kernel/process.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 | 25 +- > drivers/memory/emif.c | 2 +- > drivers/regulator/pfuze100-regulator.c | 38 +- > include/linux/notifier.h | 37 +- > include/linux/pm.h | 1 - > include/linux/reboot.h | 305 ++++++++++++-- > kernel/notifier.c | 83 ++++ > kernel/power/hibernate.c | 2 +- > kernel/reboot.c | 556 ++++++++++++++++++++++++- > 28 files changed, 985 insertions(+), 136 deletions(-) > +CC Linus Walleij, Sebastian Reichel and Philipp Zabel; whom I missed to include by accident. https://lore.kernel.org/all/20211108004524.29465-1-digetx@xxxxxxxxx/T/#t
