leds: trigger: pattern: Add support for hrtimer

Currently, led pattern trigger uses timer_list to schedule brightness
changing. As we know from timer_list API [1], it's not accurate to
milliseconds and depends on HZ granularity.

Example:
"0 10 0 0 50 10 50 0 100 10 100 0 150 10 150 0 200 10 200 0 250 10 250 0",
we expect it to be 60ms long, but it can actually be up to ~120ms
(add ~10ms for each pattern when HZ == 100).

But sometimes, userspace needs time accurate led patterns to make sure
that pattern will be executed during expected time slot.
To achieve this goal the patch introduces optional hrtimer usage for
led trigger pattern, because hrtimer is microseconds accurate timer.

[1]: kernel/time/timer.c#L104

Signed-off-by: Martin Kurbanov <mmkurbanov@salutedevices.com>
Link: https://lore.kernel.org/r/20240416201847.357099-1-mmkurbanov@salutedevices.com
Signed-off-by: Lee Jones <lee@kernel.org>

docs: ABI: sysfs-class-led-trigger-pattern: remove repeat duplication

As reported by scripts/get_abi.pl:

Warning: /sys/class/leds/<led>/repeat is defined 2 times: Documentation/ABI/testing/sysfs-class-led-driver-el15203000:0 Documentation/ABI/testing/sysfs-class-led-trigger-pattern:28

The definition for the EL15203000 is just a special case of
the sysfs led class. So, drop it and mentions the possible
exception at the class definition.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/394580bd2e007ffb640f97212973a772ed8f0409.1621413933.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: ABI: sysfs-class-led-trigger-pattern: remove hw_pattern duplication

The ABI files are supposed to be unique. Yet,
in the specific case of hw_pattern, there are some duplicated
entries as warned by scripts/get_abi.pl:

Warning: /sys/class/leds/<led>/hw_pattern is defined 3 times: Documentation/ABI/testing/sysfs-class-led-trigger-pattern:14 Documentation/ABI/testing/sysfs-class-led-driver-sc27xx:0 Documentation/ABI/testing/sysfs-class-led-driver-el15203000:0

Drop the duplication from the ABI files, moving the specific
definitions to files inside Documentation/leds.

Acked-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/038e57881550550b298e598f8f9b7f20515cbe15.1604042072.git.mchehab+huawei@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

dt-bindings: leds: Add pattern initialization from Device Tree

Document new led-pattern property for initialization of LED triggers.
The property format is trigger-specific (except being array of
integers). For pattern trigger, the explanation of pattern format was
moved to a common file shared with sysfs ABI.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>

Documentation: ABI: led-trigger-pattern: Fix typos

- Spelling s/brigntess/brightness/,
- Double "use".

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>

leds: core: Introduce LED pattern trigger

This patch adds a new LED trigger that LED device can configure
to employ software or hardware pattern engine.

Consumers can write 'pattern' file to enable the software pattern
which alters the brightness for the specified duration with one
software timer.

Moreover consumers can write 'hw_pattern' file to enable the hardware
pattern for some LED controllers which can autonomously control
brightness over time, according to some preprogrammed hardware
patterns.

Signed-off-by: Raphael Teysseyre <rteysseyre@gmail.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>