Samsung S2M Series PMIC RGB LED Driver

Description

The RGB LED on the S2M series PMIC hardware features a three-channel LED that is grouped together as a single device. Furthermore, it supports 8-bit brightness control for each channel. This LED is typically used as a status indicator in mobile devices. It also supports various parameters for hardware patterns.

The hardware pattern can be programmed using the “pattern” trigger, using the hw_pattern attribute.

/sys/class/leds/<led>/repeat

The hardware supports only indefinitely repeating patterns. The repeat attribute must be set to -1 for hardware patterns to function.

/sys/class/leds/<led>/hw_pattern

Specify a hardware pattern for the RGB LEDs.

The pattern is a series of brightness levels and durations in milliseconds. There should be only one non-zero brightness level. Unlike the results described in leds-trigger-pattern, the transitions between on and off states are smoothed out by the hardware.

Simple pattern:

"255 3000 0 1000"

255 -+ ''''''-.                     .-'''''''-.
     |         '.                 .'           '.
     |           \               /               \
     |            '.           .'                 '.
     |              '-.......-'                     '-
  0 -+-------+-------+-------+-------+-------+-------+--> time (s)
     0       1       2       3       4       5       6

As described in leds-trigger-pattern, it is also possible to use zero-length entries to disable the ramping mechanism.

On-Off pattern:

"255 1000 255 0 0 1000 0 0"

255 -+ ------+       +-------+       +-------+
     |       |       |       |       |       |
     |       |       |       |       |       |
     |       |       |       |       |       |
     |       +-------+       +-------+       +-------
  0 -+-------+-------+-------+-------+-------+-------+--> time (s)
     0       1       2       3       4       5       6