If you are using Linux as your kernel on a SoC design, you’ll be glad to know that it has an entire subsystem dedicated to LEDs!
menuconfig LEDS_TRIGGERS
bool "LED Trigger support"
depends on LEDS_CLASS
help
This option enables trigger support for the leds class.
These triggers allow kernel events to drive the LEDs and can
be configured via sysfs. If unsure, say Y.
if LEDS_TRIGGERS
...
config LEDS_TRIGGER_HEARTBEAT
tristate "LED Heartbeat Trigger"
depends on LEDS_TRIGGERS
help
This allows LEDs to be controlled by a CPU load average.
The flash frequency is a hyperbolic function of the 1-minute
load average.
If unsure, say Y.
...