Zephyr has a PWM-LED driver which makes calls to a PWM driver to control
the pin. The previous MCHP PWM-BBLED driver do not report its actual
PWM cycles, instead it reported the clock source it used: 32KHz or 48MHz.
This bug caused the LED-PWM driver set brightness to compute incorrect
parameters passed to the PWM-BBLED driver. The BBLED hardware has a
built-in divider of 256 therefore its maximum cycles are 128 and 48M/256
respectively. This change also simplified the calculations. A DT overlay
for the MEC172x EVB was added to the PWM-LED sample to demonstrate driver
operation. We found specifying >= 50 ms for the PWM period in the device
tree nodes provided a good operating range for the LED-PWM driver
parameter calculations.
Note: BBLED hardware implements an 8-bit PWM with a fixed divider of 256
and a 12-bit frequency pre-scaler. Duty cycle is represented by an 8-bit
value.
Signed-off-by: Manimaran A <manimaran.a@microchip.com>
