+++ /dev/null
-<?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
- "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
-
-<book id="regulator-api">
- <bookinfo>
- <title>Voltage and current regulator API</title>
-
- <authorgroup>
- <author>
- <firstname>Liam</firstname>
- <surname>Girdwood</surname>
- <affiliation>
- <address>
- <email>lrg@slimlogic.co.uk</email>
- </address>
- </affiliation>
- </author>
- <author>
- <firstname>Mark</firstname>
- <surname>Brown</surname>
- <affiliation>
- <orgname>Wolfson Microelectronics</orgname>
- <address>
- <email>broonie@opensource.wolfsonmicro.com</email>
- </address>
- </affiliation>
- </author>
- </authorgroup>
-
- <copyright>
- <year>2007-2008</year>
- <holder>Wolfson Microelectronics</holder>
- </copyright>
- <copyright>
- <year>2008</year>
- <holder>Liam Girdwood</holder>
- </copyright>
-
- <legalnotice>
- <para>
- 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.
- </para>
-
- <para>
- This program is distributed in the hope that it will be
- useful, but WITHOUT ANY WARRANTY; without even the implied
- warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
- See the GNU General Public License for more details.
- </para>
-
- <para>
- You should have received a copy of the GNU General Public
- License along with this program; if not, write to the Free
- Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
- MA 02111-1307 USA
- </para>
-
- <para>
- For more details see the file COPYING in the source
- distribution of Linux.
- </para>
- </legalnotice>
- </bookinfo>
-
-<toc></toc>
-
- <chapter id="intro">
- <title>Introduction</title>
- <para>
- This framework is designed to provide a standard kernel
- interface to control voltage and current regulators.
- </para>
- <para>
- 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).
- </para>
- <para>
- Note that additional (and currently more complete) documentation
- is available in the Linux kernel source under
- <filename>Documentation/power/regulator</filename>.
- </para>
-
- <sect1 id="glossary">
- <title>Glossary</title>
- <para>
- The regulator API uses a number of terms which may not be
- familiar:
- </para>
- <glossary>
-
- <glossentry>
- <glossterm>Regulator</glossterm>
- <glossdef>
- <para>
- 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.
- </para>
- </glossdef>
- </glossentry>
-
- <glossentry>
- <glossterm>Consumer</glossterm>
- <glossdef>
- <para>
- 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.
- </para>
- </glossdef>
- </glossentry>
-
- <glossentry>
- <glossterm>Power Domain</glossterm>
- <glossdef>
- <para>
- 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.
- </para>
- </glossdef>
- </glossentry>
-
- <glossentry>
- <glossterm>Power Management Integrated Circuit</glossterm>
- <acronym>PMIC</acronym>
- <glossdef>
- <para>
- 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.
- </para>
- </glossdef>
- </glossentry>
- </glossary>
- </sect1>
- </chapter>
-
- <chapter id="consumer">
- <title>Consumer driver interface</title>
- <para>
- This offers a similar API to the kernel clock framework.
- Consumer drivers use <link
- linkend='API-regulator-get'>get</link> and <link
- linkend='API-regulator-put'>put</link> operations to acquire and
- release regulators. Functions are
- provided to <link linkend='API-regulator-enable'>enable</link>
- and <link linkend='API-regulator-disable'>disable</link> the
- regulator and to get and set the runtime parameters of the
- regulator.
- </para>
- <para>
- When requesting regulators consumers use symbolic names for their
- supplies, such as "Vcc", which are mapped into actual regulator
- devices by the machine interface.
- </para>
- <para>
- A stub version of this API is provided when the regulator
- framework is not in use in order to minimise the need to use
- ifdefs.
- </para>
-
- <sect1 id="consumer-enable">
- <title>Enabling and disabling</title>
- <para>
- The regulator API provides reference counted enabling and
- disabling of regulators. Consumer devices use the <function><link
- linkend='API-regulator-enable'>regulator_enable</link></function>
- and <function><link
- linkend='API-regulator-disable'>regulator_disable</link>
- </function> functions to enable and disable regulators. Calls
- to the two functions must be balanced.
- </para>
- <para>
- Note that since multiple consumers may be using a regulator and
- machine constraints may not allow the regulator to be disabled
- there is no guarantee that calling
- <function>regulator_disable</function> will actually cause the
- supply provided by the regulator to be disabled. Consumer
- drivers should assume that the regulator may be enabled at all
- times.
- </para>
- </sect1>
-
- <sect1 id="consumer-config">
- <title>Configuration</title>
- <para>
- Some consumer devices may need to be able to dynamically
- configure their supplies. For example, MMC drivers may need to
- select the correct operating voltage for their cards. This may
- be done while the regulator is enabled or disabled.
- </para>
- <para>
- The <function><link
- linkend='API-regulator-set-voltage'>regulator_set_voltage</link>
- </function> and <function><link
- linkend='API-regulator-set-current-limit'
- >regulator_set_current_limit</link>
- </function> functions provide the primary interface for this.
- Both take ranges of voltages and currents, supporting drivers
- that do not require a specific value (eg, CPU frequency scaling
- normally permits the CPU to use a wider range of supply
- voltages at lower frequencies but does not require that the
- supply voltage be lowered). Where an exact value is required
- both minimum and maximum values should be identical.
- </para>
- </sect1>
-
- <sect1 id="consumer-callback">
- <title>Callbacks</title>
- <para>
- Callbacks may also be <link
- linkend='API-regulator-register-notifier'>registered</link>
- for events such as regulation failures.
- </para>
- </sect1>
- </chapter>
-
- <chapter id="driver">
- <title>Regulator driver interface</title>
- <para>
- Drivers for regulator chips <link
- linkend='API-regulator-register'>register</link> the regulators
- with the regulator core, providing operations structures to the
- core. A <link
- linkend='API-regulator-notifier-call-chain'>notifier</link> interface
- allows error conditions to be reported to the core.
- </para>
- <para>
- Registration should be triggered by explicit setup done by the
- platform, supplying a <link
- linkend='API-struct-regulator-init-data'>struct
- regulator_init_data</link> for the regulator containing
- <link linkend='machine-constraint'>constraint</link> and
- <link linkend='machine-supply'>supply</link> information.
- </para>
- </chapter>
-
- <chapter id="machine">
- <title>Machine interface</title>
- <para>
- This interface provides a way to define how regulators are
- connected to consumers on a given system and what the valid
- operating parameters are for the system.
- </para>
-
- <sect1 id="machine-supply">
- <title>Supplies</title>
- <para>
- Regulator supplies are specified using <link
- linkend='API-struct-regulator-consumer-supply'>struct
- regulator_consumer_supply</link>. This is done at
- <link linkend='driver'>driver registration
- time</link> as part of the machine constraints.
- </para>
- </sect1>
-
- <sect1 id="machine-constraint">
- <title>Constraints</title>
- <para>
- As well as defining the connections the machine interface
- also provides constraints defining the operations that
- clients are allowed to perform and the parameters that may be
- set. This is required since generally regulator devices will
- offer more flexibility than it is safe to use on a given
- system, for example supporting higher supply voltages than the
- consumers are rated for.
- </para>
- <para>
- This is done at <link linkend='driver'>driver
- registration time</link> by providing a <link
- linkend='API-struct-regulation-constraints'>struct
- regulation_constraints</link>.
- </para>
- <para>
- The constraints may also specify an initial configuration for the
- regulator in the constraints, which is particularly useful for
- use with static consumers.
- </para>
- </sect1>
- </chapter>
-
- <chapter id="api">
- <title>API reference</title>
- <para>
- Due to limitations of the kernel documentation framework and the
- existing layout of the source code the entire regulator API is
- documented here.
- </para>
-!Iinclude/linux/regulator/consumer.h
-!Iinclude/linux/regulator/machine.h
-!Iinclude/linux/regulator/driver.h
-!Edrivers/regulator/core.c
- </chapter>
-</book>
--- /dev/null
+.. 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.
+
+A stub version of this API is provided when the regulator framework is
+not in use in order to minimise the need to use ifdefs.
+
+Enabling and disabling
+----------------------
+
+The regulator API provides reference counted enabling and disabling of
+regulators. Consumer devices use the :c:func:`regulator_enable()` and
+:c:func:`regulator_disable()` functions to enable and disable
+regulators. Calls to the two functions must be balanced.
+
+Note that since multiple consumers may be using a regulator and machine
+constraints may not allow the regulator to be disabled there is no
+guarantee that calling :c:func:`regulator_disable()` will actually
+cause the supply provided by the regulator to be disabled. Consumer
+drivers should assume that the regulator may be enabled at all times.
+
+Configuration
+-------------
+
+Some consumer devices may need to be able to dynamically configure their
+supplies. For example, MMC drivers may need to select the correct
+operating voltage for their cards. This may be done while the regulator
+is enabled or disabled.
+
+The :c:func:`regulator_set_voltage()` and
+:c:func:`regulator_set_current_limit()` functions provide the primary
+interface for this. Both take ranges of voltages and currents, supporting
+drivers that do not require a specific value (eg, CPU frequency scaling
+normally permits the CPU to use a wider range of supply voltages at lower
+frequencies but does not require that the supply voltage be lowered). Where
+an exact value is required both minimum and maximum values should be
+identical.
+
+Callbacks
+---------
+
+Callbacks may also be registered for events such as regulation failures.
+
+Regulator driver interface
+==========================
+
+Drivers for regulator chips register the regulators with the regulator
+core, providing operations structures to the core. A notifier interface
+allows error conditions to be reported to the core.
+
+Registration should be triggered by explicit setup done by the platform,
+supplying a struct :c:type:`regulator_init_data` for the regulator
+containing constraint and supply information.
+
+Machine interface
+=================
+
+This interface provides a way to define how regulators are connected to
+consumers on a given system and what the valid operating parameters are
+for the system.
+
+Supplies
+--------
+
+Regulator supplies are specified using struct
+:c:type:`regulator_consumer_supply`. This is done at driver registration
+time as part of the machine constraints.
+
+Constraints
+-----------
+
+As well as defining the connections the machine interface also provides
+constraints defining the operations that clients are allowed to perform
+and the parameters that may be set. This is required since generally
+regulator devices will offer more flexibility than it is safe to use on
+a given system, for example supporting higher supply voltages than the
+consumers are rated for.
+
+This is done at driver registration time` by providing a
+struct :c:type:`regulation_constraints`.
+
+The constraints may also specify an initial configuration for the
+regulator in the constraints, which is particularly useful for use with
+static consumers.
+
+API reference
+=============
+
+Due to limitations of the kernel documentation framework and the
+existing layout of the source code the entire regulator API is
+documented here.
+
+.. kernel-doc:: include/linux/regulator/consumer.h
+ :internal:
+
+.. kernel-doc:: include/linux/regulator/machine.h
+ :internal:
+
+.. kernel-doc:: include/linux/regulator/driver.h
+ :internal:
+
+.. kernel-doc:: drivers/regulator/core.c
+ :export:
projects / karo-tx-linux.git / commitdiff