Configure and Debug PWM

Configure PWM Pins

Configure the jh7110-visionfive-v2.dtsi file that is under /linux/arch/riscv/boot/dts/starfive.

Up to 8 channels are supported form PWM. You can configure the unoccupied GPIOs as desired. The following is the default setting.

To debug PWM GPIO:

Execute the following to configure the PWM channel:
```
cd /sys/class/pwm/pwmchip0
echo 0 > export
```
Execute the following to configure the PWM period:
```
cd pwm0
echo 5000000 > period
```
Execute the following to configure the PWM duty cycle:
```
echo 1000000 > duty_cycle
```
Note: A duty cycle is the fraction of one period in which a signal or system is active.
Use an oscilloscope to measure the corresponding pin and check the PWM period and duty cycle.