Platforms have a set of voltage and current regulators to dynamically control regulator power output in order to save power or to match certain system operating points. E.g: LCD backlight driver would need to change the current limit to vary the backlight brightness.
Arm client platforms with DT make use of the regulator binding to describe regulator devices and consumer devices for regulators. Device drivers use the regulator framework to dynamically enable/disable voltage rails or configure the voltage or current limits.
ACPI bindings for Regulator
ACPI doesn’t have any bindings available for the regulator specifically and the regulator enable/disable etc. are typically handled by the ACPI device power methods.
Looking at a diverse set of devices like low-speed/high-speed IO, sound cards, video, backlight, etc. for multiple Arm platforms, there doesn’t seem to any need for voltage regulator binding beyond what is required for power saving which is already handled by the device power methods.