Introduce a mechanism for drivers to extend the properties implemented by a power supply. Motivation ---------- Various drivers, mostly in platform/x86 extend the ACPI battery driver with additional sysfs attributes to implement more UAPIs than are exposed through ACPI by using various side-channels, like WMI, nonstandard ACPI or EC communication. While the created sysfs attributes look similar to the attributes provided by the powersupply core, there are various deficiencies: * They don't show up in uevent payload. * They can't be queried with the standard in-kernel APIs. * They don't work with triggers. * The extending driver has to reimplement all of the parsing, formatting and sysfs display logic. * Writing a extension driver is completely different from writing a normal power supply driver. * ~Properties can not be properly overriden.~ (Overriding is now explicitly forbidden) The proposed extension API avoids all of these issues. An extension is just a "struct power_supply_ext" with the same kind of callbacks as in a normal "struct power_supply_desc". The API is meant to be used via battery_hook_register(), the same way as the current extensions. Further usecases are fuel gauges and the existing battery_info properties. When testing, please enable lockdep to make sure the locking is correct. The series is based on the linux-power-supply/for-next branch. Contents -------- * Patch 1 cleans up the logging messages of the ACPI battery hooks * Patch 2 implements the extension API itself. * Patch 3 adds extension support to test_power.c * Patch 4 converts the in-tree cros_charge-control driver to the extension API. Open issues ----------- * As this is only useful with the hooks of CONFIG_ACPI_BATTERY, should it also be gated behind this or another config? * Is an rw_semaphore acceptable? [0] https://lore.kernel.org/lkml/20240528-cros_ec-charge-control-v2-0-81fb27e1cff4@xxxxxxxxxxxxxx/ Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx> --- Changes in v5: - Drop already picked up patches - Simplify power_supply_ext_has_property() - Handle failure of power_supply_update_sysfs_and_hwmon() - Reduce some locking scopes - Add missing locking to power_supply_show_charge_behaviour() - Improve sanity checks in power_supply_register_extension() - Implement writeable property in test_power battery - Rename ACPI battery hook messages for clarity - Link to v4: https://lore.kernel.org/r/20241111-power-supply-extensions-v4-0-7240144daa8e@xxxxxxxxxxxxxx Changes in v4: - Drop RFC state - Integrate locking commit - Reregister hwmon device - Link to v3: https://lore.kernel.org/r/20240904-power-supply-extensions-v3-0-62efeb93f8ec@xxxxxxxxxxxxxx Changes in v3: - Make naming more consistent - Readd locking - Allow multiple active extensions - Allow passing a "void *ext_data" when registering - Switch example driver from system76 to cros_charge-control - Link to v2: https://lore.kernel.org/r/20240608-power-supply-extensions-v2-0-2dcd35b012ad@xxxxxxxxxxxxxx Changes in v2: - Drop locking patch, let's figure out the API first - Allow registration of multiple extensions - Pass extension to extension callbacks as parameter - Disallow property overlap between extensions and core psy - Drop system76/pdx86 maintainers, as the system76 changes are only RFC state anyways - Link to v1: https://lore.kernel.org/r/20240606-power-supply-extensions-v1-0-b45669290bdc@xxxxxxxxxxxxxx --- Thomas Weißschuh (4): ACPI: battery: Rename extensions to hook in messages power: supply: core: implement extension API power: supply: test-power: implement a power supply extension power: supply: cros_charge-control: implement a power supply extension drivers/acpi/battery.c | 14 +- drivers/power/supply/cros_charge-control.c | 217 ++++++++++++----------------- drivers/power/supply/power_supply.h | 14 ++ drivers/power/supply/power_supply_core.c | 159 +++++++++++++++++++-- drivers/power/supply/power_supply_sysfs.c | 26 +++- drivers/power/supply/test_power.c | 111 +++++++++++++++ include/linux/power_supply.h | 32 +++++ 7 files changed, 427 insertions(+), 146 deletions(-) --- base-commit: 39f3bd9c9a27d526858da153090376decdf7bfea change-id: 20240602-power-supply-extensions-07d949f509d9 Best regards, -- Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
