On 07.02.2018 15.58, Ognjen Galic wrote:
This is a patch that implements a generic hooking API for the
generic ACPI battery driver.
With this new generic API, drivers can expose platform specific
behaviour via sysfs attributes in /sys/class/power_supply/BATn/
in a generic way.
A perfect example of the need for this API are Lenovo ThinkPads.
Lenovo ThinkPads have a ACPI extension that allows the setting of
start and stop charge thresholds in the EC and battery firmware
via ACPI. The thinkpad_acpi module can use this API to expose
sysfs attributes that it controls inside the ACPI battery driver
sysfs tree, under /sys/class/power_supply/BATN/.
The file drivers/acpi/battery.h has been moved to
include/acpi/battery.h and the includes inside ac.c, sbs.c, and
battery.c have been adjusted to reflect that.
When drivers hooks into the API, the API calls add_battery() for
each battery in the system that passes it a acpi_battery
struct. Then, the drivers can use device_create_file() to create
new sysfs attributes with that struct and identify the batteries
for per-battery attributes.
Hi
I did that, when I implemented charge threshold support for ASUS
laptops[1][2].
It works very well but I can't control the threshold with udev (also
reported by another user here[3]). So I did a bit of digging and the
doc[4] states: "If attributes are added after the device is registered,
then userspace won’t get notified and userspace will not know about the
new attributes.", which seems to be the way the current code works:
power_supply_register_no_ws is called[5] and if it success all the hooks
are run.
Looking at the code I'm not sure there is a easy way to fix it, do you
have any good ideas?
Best
Kristian Klausen
[1]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d507a54f5865d8dcbdd16c66a1a2da15640878ca
[2]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7973353e92ee1e7ca3b2eb361a4b7cb66c92abee
[3]
https://www.reddit.com/r/linuxhardware/comments/g8kpee/psa_kernel_54_added_the_ability_to_set_a_battery/fp8bwgu/
[4]
https://www.kernel.org/doc/html/v5.8-rc2/driver-api/driver-model/device.html
[5]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/acpi/battery.c?id=8c3f6993c221cc1a2588046e3ff32d64580396b7#n854
Signed-off-by: Ognjen Galic <smclt30p@xxxxxxxxx>
