The Raspberry Pi 3B+ contains the MaxLinear (previously Exar) MxL7704 power management chip (PMIC) with I2C interface for "on-line" reconfiguration of power sequencing and internal voltages.1 This is the first time a Raspberry Pi contains a software programmable power management chip. Which driver configures power management with this chip ?
Grepping through the latest Pi kernel (4.16.0) .c, .h, and Kconfig files for "7704", "Exar", and "MaxLinear" doesn't show anything appropriate. I guess there could be a generic interface but that seems unlikely.– goldilocks ♦Mar 15, 2018 at 14:12
The PMIC of the Raspberry PI 3B+ is not controlled by Linux, but the closed-source firmware1.