I know it’s been a while since you posted this, but just in case you haven’t figured it out, or if anyone else stumbles upon this in the future, here’s a example of enabling a PWM channel on the t113s. Pwm by ConnorRigby · Pull Request #1 · ConnorRigby/nerves_system_underglow3 · GitHub
it should be the same on the D1. The source file for pinctrl will be in here Making sure you're not a bot!
