What:		/sys/class/leds/<led>/hw_pattern
Date:		September 2018
KernelVersion:	4.20
Description:
		Specify a hardware pattern for the SC27XX LED. For the SC27XX
		LED controller, it only supports 4 stages to make a single
		hardware pattern, which is used to configure the rise time,
		high time, fall time and low time for the breathing mode.

		For the breathing mode, the SC27XX LED only expects one brightness
		for the high stage. To be compatible with the hardware pattern
		format, we should set brightness as 0 for rise stage, fall
		stage and low stage.

		Min stage duration: 125 ms
		Max stage duration: 31875 ms

		Since the stage duration step is 125 ms, the duration should be
		a multiplier of 125, like 125ms, 250ms, 375ms, 500ms ... 31875ms.

		Thus the format of the hardware pattern values should be:
		"0 rise_duration brightness high_duration 0 fall_duration 0 low_duration".