Documentation/driver-api/regulator.rst

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.. Copyright 2007-2008 Wolfson Microelectronics

..   This documentation is free software; you can redistribute
..   it and/or modify it under the terms of the GNU General Public
..   License version 2 as published by the Free Software Foundation.

=================================
Voltage and current regulator API
=================================

:Author: Liam Girdwood
:Author: Mark Brown

Introduction
============

This framework is designed to provide a standard kernel interface to
control voltage and current regulators.

The intention is to allow systems to dynamically control regulator power
output in order to save power and prolong battery life. This applies to
both voltage regulators (where voltage output is controllable) and
current sinks (where current limit is controllable).

Note that additional (and currently more complete) documentation is
available in the Linux kernel source under
``Documentation/power/regulator``.

Glossary
--------

The regulator API uses a number of terms which may not be familiar:

Regulator

    Electronic device that supplies power to other devices. Most regulators
    can enable and disable their output and some can also control their
    output voltage or current.

Consumer

    Electronic device which consumes power provided by a regulator. These
    may either be static, requiring only a fixed supply, or dynamic,
    requiring active management of the regulator at runtime.

Power Domain

    The electronic circuit supplied by a given regulator, including the
    regulator and all consumer devices. The configuration of the regulator
    is shared between all the components in the circuit.

Power Management Integrated Circuit (PMIC)

    An IC which contains numerous regulators and often also other
    subsystems. In an embedded system the primary PMIC is often equivalent
    to a combination of the PSU and southbridge in a desktop system.

Consumer driver interface
=========================

This offers a similar API to the kernel clock framework. Consumer
drivers use `get <#API-regulator-get>`__ and
`put <#API-regulator-put>`__ operations to acquire and release
regulators. Functions are provided to `enable <#API-regulator-enable>`__
and `disable <#API-regulator-disable>`__ the regulator and to get and
set the runtime parameters of the regulator.

When requesting regulators consumers use symbolic names for their
supplies, such as "Vcc", which are mapped into actual regulator devices
by the machine interface.

Annotation

Implementation Notes