| Message ID | 20240608-power-supply-extensions-v2-0-2dcd35b012ad@weissschuh.net (mailing list archive) |
|---|---|
| Headers | show |
| Series | power: supply: extension API | expand |
On Sat, 08 Jun 2024 21:19:36 +0200, Thomas Weißschuh wrote: > 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. > > [...] Applied, thanks! [1/5] power: supply: sysfs: use power_supply_property_is_writeable() commit: be6299c6e55e971ffc060495708740a59aa0e45b Best regards,
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 not implemented anymore, can be readded) 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. For example my upcoming cros_ec charge control driver[0] saves 80 lines of code with this patchset. Contents -------- * Patch 1 and 2 are generic preparation patches, that probably make sense without this series. * Patch 3 implements the extension API itself. * Patch 4 implements a PoC locking scheme for the extension API. * Patch 5 adds extension support to test_power.c * Patch 6 converts the in-tree platform/x86/system76 driver to the extension API. Open issues ----------- * Newly registered properties will not show up in hwmon. To do that properly would require some changes in the hwmon core. As far as I know, no current driver would extend the hwmon properties anyways. * As this is only useful with the hooks of CONFIG_ACPI_BATTERY, should it also be gated behind this or another config? * Only one extension can be used at a time. So far this should be enough, having more would complicate the implementation. * Is an rw_semaphore acceptable? [0] https://lore.kernel.org/lkml/20240528-cros_ec-charge-control-v2-0-81fb27e1cff4@weissschuh.net/ Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> --- 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@weissschuh.net --- Thomas Weißschuh (5): power: supply: sysfs: use power_supply_property_is_writeable() power: supply: core: avoid iterating properties directly power: supply: core: implement extension API power: supply: test-power: implement a power supply extension platform/x86: system76: Use power_supply extension API drivers/platform/x86/system76_acpi.c | 93 ++++++++++++---------- drivers/power/supply/power_supply.h | 12 +++ drivers/power/supply/power_supply_core.c | 128 ++++++++++++++++++++++++++++-- drivers/power/supply/power_supply_hwmon.c | 48 +++++------ drivers/power/supply/power_supply_sysfs.c | 50 +++++++++--- drivers/power/supply/test_power.c | 101 +++++++++++++++++++++++ include/linux/power_supply.h | 26 ++++++ 7 files changed, 371 insertions(+), 87 deletions(-) --- base-commit: 061d1af7b0305227182bd9da60c7706c079348b7 change-id: 20240602-power-supply-extensions-07d949f509d9 Best regards,