summaryrefslogtreecommitdiffstats
path: root/Documentation
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2008-08-01 19:56:40 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2008-08-01 19:56:40 +0200
commit561b35b341b1aeeab486affe1ede0ee6640ce33b (patch)
treea7570737884bef3c15db98cae629a82ce3586b3c /Documentation
parentMerge branch 'hotfixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jmor... (diff)
parentregulator: TI bq24022 Li-Ion Charger driver (diff)
downloadlinux-561b35b341b1aeeab486affe1ede0ee6640ce33b.tar.xz
linux-561b35b341b1aeeab486affe1ede0ee6640ce33b.zip
Merge branch 'reg-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/lrg/voltage-2.6
* 'reg-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/lrg/voltage-2.6: regulator: TI bq24022 Li-Ion Charger driver regulator: maintainers - add maintainers for regulator framework. regulator: documentation - ABI regulator: documentation - machine regulator: documentation - regulator driver regulator: documentation - consumer interface regulator: documentation - overview regulator: core kbuild files regulator: regulator test harness regulator: add support for fixed regulators. regulator: regulator framework core regulator: fixed regulator interface regulator: machine driver interface regulator: regulator driver interface regulator: consumer device interface
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/ABI/testing/sysfs-class-regulator315
-rw-r--r--Documentation/power/regulator/consumer.txt182
-rw-r--r--Documentation/power/regulator/machine.txt101
-rw-r--r--Documentation/power/regulator/overview.txt171
-rw-r--r--Documentation/power/regulator/regulator.txt30
5 files changed, 799 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-class-regulator b/Documentation/ABI/testing/sysfs-class-regulator
new file mode 100644
index 000000000000..79a4a75b2d2c
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-regulator
@@ -0,0 +1,315 @@
+What: /sys/class/regulator/.../state
+Date: April 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ state. This holds the regulator output state.
+
+ This will be one of the following strings:
+
+ 'enabled'
+ 'disabled'
+ 'unknown'
+
+ 'enabled' means the regulator output is ON and is supplying
+ power to the system.
+
+ 'disabled' means the regulator output is OFF and is not
+ supplying power to the system..
+
+ 'unknown' means software cannot determine the state.
+
+ NOTE: this field can be used in conjunction with microvolts
+ and microamps to determine regulator output levels.
+
+
+What: /sys/class/regulator/.../type
+Date: April 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ type. This holds the regulator type.
+
+ This will be one of the following strings:
+
+ 'voltage'
+ 'current'
+ 'unknown'
+
+ 'voltage' means the regulator output voltage can be controlled
+ by software.
+
+ 'current' means the regulator output current limit can be
+ controlled by software.
+
+ 'unknown' means software cannot control either voltage or
+ current limit.
+
+
+What: /sys/class/regulator/.../microvolts
+Date: April 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ microvolts. This holds the regulator output voltage setting
+ measured in microvolts (i.e. E-6 Volts).
+
+ NOTE: This value should not be used to determine the regulator
+ output voltage level as this value is the same regardless of
+ whether the regulator is enabled or disabled.
+
+
+What: /sys/class/regulator/.../microamps
+Date: April 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ microamps. This holds the regulator output current limit
+ setting measured in microamps (i.e. E-6 Amps).
+
+ NOTE: This value should not be used to determine the regulator
+ output current level as this value is the same regardless of
+ whether the regulator is enabled or disabled.
+
+
+What: /sys/class/regulator/.../opmode
+Date: April 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ opmode. This holds the regulator operating mode setting.
+
+ The opmode value can be one of the following strings:
+
+ 'fast'
+ 'normal'
+ 'idle'
+ 'standby'
+ 'unknown'
+
+ The modes are described in include/linux/regulator/regulator.h
+
+ NOTE: This value should not be used to determine the regulator
+ output operating mode as this value is the same regardless of
+ whether the regulator is enabled or disabled.
+
+
+What: /sys/class/regulator/.../min_microvolts
+Date: April 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ min_microvolts. This holds the minimum safe working regulator
+ output voltage setting for this domain measured in microvolts.
+
+ NOTE: this will return the string 'constraint not defined' if
+ the power domain has no min microvolts constraint defined by
+ platform code.
+
+
+What: /sys/class/regulator/.../max_microvolts
+Date: April 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ max_microvolts. This holds the maximum safe working regulator
+ output voltage setting for this domain measured in microvolts.
+
+ NOTE: this will return the string 'constraint not defined' if
+ the power domain has no max microvolts constraint defined by
+ platform code.
+
+
+What: /sys/class/regulator/.../min_microamps
+Date: April 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ min_microamps. This holds the minimum safe working regulator
+ output current limit setting for this domain measured in
+ microamps.
+
+ NOTE: this will return the string 'constraint not defined' if
+ the power domain has no min microamps constraint defined by
+ platform code.
+
+
+What: /sys/class/regulator/.../max_microamps
+Date: April 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ max_microamps. This holds the maximum safe working regulator
+ output current limit setting for this domain measured in
+ microamps.
+
+ NOTE: this will return the string 'constraint not defined' if
+ the power domain has no max microamps constraint defined by
+ platform code.
+
+
+What: /sys/class/regulator/.../num_users
+Date: April 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ num_users. This holds the number of consumer devices that
+ have called regulator_enable() on this regulator.
+
+
+What: /sys/class/regulator/.../requested_microamps
+Date: April 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ requested_microamps. This holds the total requested load
+ current in microamps for this regulator from all its consumer
+ devices.
+
+
+What: /sys/class/regulator/.../parent
+Date: April 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Some regulator directories will contain a link called parent.
+ This points to the parent or supply regulator if one exists.
+
+What: /sys/class/regulator/.../suspend_mem_microvolts
+Date: May 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ suspend_mem_microvolts. This holds the regulator output
+ voltage setting for this domain measured in microvolts when
+ the system is suspended to memory.
+
+ NOTE: this will return the string 'not defined' if
+ the power domain has no suspend to memory voltage defined by
+ platform code.
+
+What: /sys/class/regulator/.../suspend_disk_microvolts
+Date: May 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ suspend_disk_microvolts. This holds the regulator output
+ voltage setting for this domain measured in microvolts when
+ the system is suspended to disk.
+
+ NOTE: this will return the string 'not defined' if
+ the power domain has no suspend to disk voltage defined by
+ platform code.
+
+What: /sys/class/regulator/.../suspend_standby_microvolts
+Date: May 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ suspend_standby_microvolts. This holds the regulator output
+ voltage setting for this domain measured in microvolts when
+ the system is suspended to standby.
+
+ NOTE: this will return the string 'not defined' if
+ the power domain has no suspend to standby voltage defined by
+ platform code.
+
+What: /sys/class/regulator/.../suspend_mem_mode
+Date: May 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ suspend_mem_mode. This holds the regulator operating mode
+ setting for this domain when the system is suspended to
+ memory.
+
+ NOTE: this will return the string 'not defined' if
+ the power domain has no suspend to memory mode defined by
+ platform code.
+
+What: /sys/class/regulator/.../suspend_disk_mode
+Date: May 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ suspend_disk_mode. This holds the regulator operating mode
+ setting for this domain when the system is suspended to disk.
+
+ NOTE: this will return the string 'not defined' if
+ the power domain has no suspend to disk mode defined by
+ platform code.
+
+What: /sys/class/regulator/.../suspend_standby_mode
+Date: May 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ suspend_standby_mode. This holds the regulator operating mode
+ setting for this domain when the system is suspended to
+ standby.
+
+ NOTE: this will return the string 'not defined' if
+ the power domain has no suspend to standby mode defined by
+ platform code.
+
+What: /sys/class/regulator/.../suspend_mem_state
+Date: May 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ suspend_mem_state. This holds the regulator operating state
+ when suspended to memory.
+
+ This will be one of the following strings:
+
+ 'enabled'
+ 'disabled'
+ 'not defined'
+
+What: /sys/class/regulator/.../suspend_disk_state
+Date: May 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ suspend_disk_state. This holds the regulator operating state
+ when suspended to disk.
+
+ This will be one of the following strings:
+
+ 'enabled'
+ 'disabled'
+ 'not defined'
+
+What: /sys/class/regulator/.../suspend_standby_state
+Date: May 2008
+KernelVersion: 2.6.26
+Contact: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+Description:
+ Each regulator directory will contain a field called
+ suspend_standby_state. This holds the regulator operating
+ state when suspended to standby.
+
+ This will be one of the following strings:
+
+ 'enabled'
+ 'disabled'
+ 'not defined'
diff --git a/Documentation/power/regulator/consumer.txt b/Documentation/power/regulator/consumer.txt
new file mode 100644
index 000000000000..82b7a43aadba
--- /dev/null
+++ b/Documentation/power/regulator/consumer.txt
@@ -0,0 +1,182 @@
+Regulator Consumer Driver Interface
+===================================
+
+This text describes the regulator interface for consumer device drivers.
+Please see overview.txt for a description of the terms used in this text.
+
+
+1. Consumer Regulator Access (static & dynamic drivers)
+=======================================================
+
+A consumer driver can get access to it's supply regulator by calling :-
+
+regulator = regulator_get(dev, "Vcc");
+
+The consumer passes in it's struct device pointer and power supply ID. The core
+then finds the correct regulator by consulting a machine specific lookup table.
+If the lookup is successful then this call will return a pointer to the struct
+regulator that supplies this consumer.
+
+To release the regulator the consumer driver should call :-
+
+regulator_put(regulator);
+
+Consumers can be supplied by more than one regulator e.g. codec consumer with
+analog and digital supplies :-
+
+digital = regulator_get(dev, "Vcc"); /* digital core */
+analog = regulator_get(dev, "Avdd"); /* analog */
+
+The regulator access functions regulator_get() and regulator_put() will
+usually be called in your device drivers probe() and remove() respectively.
+
+
+2. Regulator Output Enable & Disable (static & dynamic drivers)
+====================================================================
+
+A consumer can enable it's power supply by calling:-
+
+int regulator_enable(regulator);
+
+NOTE: The supply may already be enabled before regulator_enabled() is called.
+This may happen if the consumer shares the regulator or the regulator has been
+previously enabled by bootloader or kernel board initialization code.
+
+A consumer can determine if a regulator is enabled by calling :-
+
+int regulator_is_enabled(regulator);
+
+This will return > zero when the regulator is enabled.
+
+
+A consumer can disable it's supply when no longer needed by calling :-
+
+int regulator_disable(regulator);
+
+NOTE: This may not disable the supply if it's shared with other consumers. The
+regulator will only be disabled when the enabled reference count is zero.
+
+Finally, a regulator can be forcefully disabled in the case of an emergency :-
+
+int regulator_force_disable(regulator);
+
+NOTE: this will immediately and forcefully shutdown the regulator output. All
+consumers will be powered off.
+
+
+3. Regulator Voltage Control & Status (dynamic drivers)
+======================================================
+
+Some consumer drivers need to be able to dynamically change their supply
+voltage to match system operating points. e.g. CPUfreq drivers can scale
+voltage along with frequency to save power, SD drivers may need to select the
+correct card voltage, etc.
+
+Consumers can control their supply voltage by calling :-
+
+int regulator_set_voltage(regulator, min_uV, max_uV);
+
+Where min_uV and max_uV are the minimum and maximum acceptable voltages in
+microvolts.
+
+NOTE: this can be called when the regulator is enabled or disabled. If called
+when enabled, then the voltage changes instantly, otherwise the voltage
+configuration changes and the voltage is physically set when the regulator is
+next enabled.
+
+The regulators configured voltage output can be found by calling :-
+
+int regulator_get_voltage(regulator);
+
+NOTE: get_voltage() will return the configured output voltage whether the
+regulator is enabled or disabled and should NOT be used to determine regulator
+output state. However this can be used in conjunction with is_enabled() to
+determine the regulator physical output voltage.
+
+
+4. Regulator Current Limit Control & Status (dynamic drivers)
+===========================================================
+
+Some consumer drivers need to be able to dynamically change their supply
+current limit to match system operating points. e.g. LCD backlight driver can
+change the current limit to vary the backlight brightness, USB drivers may want
+to set the limit to 500mA when supplying power.
+
+Consumers can control their supply current limit by calling :-
+
+int regulator_set_current_limit(regulator, min_uV, max_uV);
+
+Where min_uA and max_uA are the minimum and maximum acceptable current limit in
+microamps.
+
+NOTE: this can be called when the regulator is enabled or disabled. If called
+when enabled, then the current limit changes instantly, otherwise the current
+limit configuration changes and the current limit is physically set when the
+regulator is next enabled.
+
+A regulators current limit can be found by calling :-
+
+int regulator_get_current_limit(regulator);
+
+NOTE: get_current_limit() will return the current limit whether the regulator
+is enabled or disabled and should not be used to determine regulator current
+load.
+
+
+5. Regulator Operating Mode Control & Status (dynamic drivers)
+=============================================================
+
+Some consumers can further save system power by changing the operating mode of
+their supply regulator to be more efficient when the consumers operating state
+changes. e.g. consumer driver is idle and subsequently draws less current
+
+Regulator operating mode can be changed indirectly or directly.
+
+Indirect operating mode control.
+--------------------------------
+Consumer drivers can request a change in their supply regulator operating mode
+by calling :-
+
+int regulator_set_optimum_mode(struct regulator *regulator, int load_uA);
+
+This will cause the core to recalculate the total load on the regulator (based
+on all it's consumers) and change operating mode (if necessary and permitted)
+to best match the current operating load.
+
+The load_uA value can be determined from the consumers datasheet. e.g.most
+datasheets have tables showing the max current consumed in certain situations.
+
+Most consumers will use indirect operating mode control since they have no
+knowledge of the regulator or whether the regulator is shared with other
+consumers.
+
+Direct operating mode control.
+------------------------------
+Bespoke or tightly coupled drivers may want to directly control regulator
+operating mode depending on their operating point. This can be achieved by
+calling :-
+
+int regulator_set_mode(struct regulator *regulator, unsigned int mode);
+unsigned int regulator_get_mode(struct regulator *regulator);
+
+Direct mode will only be used by consumers that *know* about the regulator and
+are not sharing the regulator with other consumers.
+
+
+6. Regulator Events
+===================
+Regulators can notify consumers of external events. Events could be received by
+consumers under regulator stress or failure conditions.
+
+Consumers can register interest in regulator events by calling :-
+
+int regulator_register_notifier(struct regulator *regulator,
+ struct notifier_block *nb);
+
+Consumers can uregister interest by calling :-
+
+int regulator_unregister_notifier(struct regulator *regulator,
+ struct notifier_block *nb);
+
+Regulators use the kernel notifier framework to send event to thier interested
+consumers.
diff --git a/Documentation/power/regulator/machine.txt b/Documentation/power/regulator/machine.txt
new file mode 100644
index 000000000000..c9a35665cf70
--- /dev/null
+++ b/Documentation/power/regulator/machine.txt
@@ -0,0 +1,101 @@
+Regulator Machine Driver Interface
+===================================
+
+The regulator machine driver interface is intended for board/machine specific
+initialisation code to configure the regulator subsystem. Typical things that
+machine drivers would do are :-
+
+ 1. Regulator -> Device mapping.
+ 2. Regulator supply configuration.
+ 3. Power Domain constraint setting.
+
+
+
+1. Regulator -> device mapping
+==============================
+Consider the following machine :-
+
+ Regulator-1 -+-> Regulator-2 --> [Consumer A @ 1.8 - 2.0V]
+ |
+ +-> [Consumer B @ 3.3V]
+
+The drivers for consumers A & B must be mapped to the correct regulator in
+order to control their power supply. This mapping can be achieved in machine
+initialisation code by calling :-
+
+int regulator_set_device_supply(const char *regulator, struct device *dev,
+ const char *supply);
+
+and is shown with the following code :-
+
+regulator_set_device_supply("Regulator-1", devB, "Vcc");
+regulator_set_device_supply("Regulator-2", devA, "Vcc");
+
+This maps Regulator-1 to the 'Vcc' supply for Consumer B and maps Regulator-2
+to the 'Vcc' supply for Consumer A.
+
+
+2. Regulator supply configuration.
+==================================
+Consider the following machine (again) :-
+
+ Regulator-1 -+-> Regulator-2 --> [Consumer A @ 1.8 - 2.0V]
+ |
+ +-> [Consumer B @ 3.3V]
+
+Regulator-1 supplies power to Regulator-2. This relationship must be registered
+with the core so that Regulator-1 is also enabled when Consumer A enables it's
+supply (Regulator-2).
+
+This relationship can be register with the core via :-
+
+int regulator_set_supply(const char *regulator, const char *regulator_supply);
+
+In this example we would use the following code :-
+
+regulator_set_supply("Regulator-2", "Regulator-1");
+
+Relationships can be queried by calling :-
+
+const char *regulator_get_supply(const char *regulator);
+
+
+3. Power Domain constraint setting.
+===================================
+Each power domain within a system has physical constraints on voltage and
+current. This must be defined in software so that the power domain is always
+operated within specifications.
+
+Consider the following machine (again) :-
+
+ Regulator-1 -+-> Regulator-2 --> [Consumer A @ 1.8 - 2.0V]
+ |
+ +-> [Consumer B @ 3.3V]
+
+This gives us two regulators and two power domains:
+
+ Domain 1: Regulator-2, Consumer B.
+ Domain 2: Consumer A.
+
+Constraints can be registered by calling :-
+
+int regulator_set_platform_constraints(const char *regulator,
+ struct regulation_constraints *constraints);
+
+The example is defined as follows :-
+
+struct regulation_constraints domain_1 = {
+ .min_uV = 3300000,
+ .max_uV = 3300000,
+ .valid_modes_mask = REGULATOR_MODE_NORMAL,
+};
+
+struct regulation_constraints domain_2 = {
+ .min_uV = 1800000,
+ .max_uV = 2000000,
+ .valid_ops_mask = REGULATOR_CHANGE_VOLTAGE,
+ .valid_modes_mask = REGULATOR_MODE_NORMAL,
+};
+
+regulator_set_platform_constraints("Regulator-1", &domain_1);
+regulator_set_platform_constraints("Regulator-2", &domain_2);
diff --git a/Documentation/power/regulator/overview.txt b/Documentation/power/regulator/overview.txt
new file mode 100644
index 000000000000..bdcb332bd7fb
--- /dev/null
+++ b/Documentation/power/regulator/overview.txt
@@ -0,0 +1,171 @@
+Linux voltage and current regulator framework
+=============================================
+
+About
+=====
+
+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).
+
+(C) 2008 Wolfson Microelectronics PLC.
+Author: Liam Girdwood <lg@opensource.wolfsonmicro.com>
+
+
+Nomenclature
+============
+
+Some terms used in this document:-
+
+ o Regulator - Electronic device that supplies power to other devices.
+ Most regulators can enable and disable their output whilst
+ some can control their output voltage and or current.
+
+ Input Voltage -> Regulator -> Output Voltage
+
+
+ o PMIC - Power Management IC. An IC that contains numerous regulators
+ and often contains other susbsystems.
+
+
+ o Consumer - Electronic device that is supplied power by a regulator.
+ Consumers can be classified into two types:-
+
+ Static: consumer does not change it's supply voltage or
+ current limit. It only needs to enable or disable it's
+ power supply. It's supply voltage is set by the hardware,
+ bootloader, firmware or kernel board initialisation code.
+
+ Dynamic: consumer needs to change it's supply voltage or
+ current limit to meet operation demands.
+
+
+ o Power Domain - Electronic circuit that is supplied it's input power by the
+ output power of a regulator, switch or by another power
+ domain.
+
+ The supply regulator may be behind a switch(s). i.e.
+
+ Regulator -+-> Switch-1 -+-> Switch-2 --> [Consumer A]
+ | |
+ | +-> [Consumer B], [Consumer C]
+ |
+ +-> [Consumer D], [Consumer E]
+
+ That is one regulator and three power domains:
+
+ Domain 1: Switch-1, Consumers D & E.
+ Domain 2: Switch-2, Consumers B & C.
+ Domain 3: Consumer A.
+
+ and this represents a "supplies" relationship:
+
+ Domain-1 --> Domain-2 --> Domain-3.
+
+ A power domain may have regulators that are supplied power
+ by other regulators. i.e.
+
+ Regulator-1 -+-> Regulator-2 -+-> [Consumer A]
+ |
+ +-> [Consumer B]
+
+ This gives us two regulators and two power domains:
+
+ Domain 1: Regulator-2, Consumer B.
+ Domain 2: Consumer A.
+
+ and a "supplies" relationship:
+
+ Domain-1 --> Domain-2
+
+
+ o Constraints - Constraints are used to define power levels for performance
+ and hardware protection. Constraints exist at three levels:
+
+ Regulator Level: This is defined by the regulator hardware
+ operating parameters and is specified in the regulator
+ datasheet. i.e.
+
+ - voltage output is in the range 800mV -> 3500mV.
+ - regulator current output limit is 20mA @ 5V but is
+ 10mA @ 10V.
+
+ Power Domain Level: This is defined in software by kernel
+ level board initialisation code. It is used to constrain a
+ power domain to a particular power range. i.e.
+
+ - Domain-1 voltage is 3300mV
+ - Domain-2 voltage is 1400mV -> 1600mV
+ - Domain-3 current limit is 0mA -> 20mA.
+
+ Consumer Level: This is defined by consumer drivers
+ dynamically setting voltage or current limit levels.
+
+ e.g. a consumer backlight driver asks for a current increase
+ from 5mA to 10mA to increase LCD illumination. This passes
+ to through the levels as follows :-
+
+ Consumer: need to increase LCD brightness. Lookup and
+ request next current mA value in brightness table (the
+ consumer driver could be used on several different
+ personalities based upon the same reference device).
+
+ Power Domain: is the new current limit within the domain
+ operating limits for this domain and system state (e.g.
+ battery power, USB power)
+
+ Regulator Domains: is the new current limit within the
+ regulator operating parameters for input/ouput voltage.
+
+ If the regulator request passes all the constraint tests
+ then the new regulator value is applied.
+
+
+Design
+======
+
+The framework is designed and targeted at SoC based devices but may also be
+relevant to non SoC devices and is split into the following four interfaces:-
+
+
+ 1. Consumer driver interface.
+
+ This uses a similar API to the kernel clock interface in that consumer
+ drivers can get and put a regulator (like they can with clocks atm) and
+ get/set voltage, current limit, mode, enable and disable. This should
+ allow consumers complete control over their supply voltage and current
+ limit. This also compiles out if not in use so drivers can be reused in
+ systems with no regulator based power control.
+
+ See Documentation/power/regulator/consumer.txt
+
+ 2. Regulator driver interface.
+
+ This allows regulator drivers to register their regulators and provide
+ operations to the core. It also has a notifier call chain for propagating
+ regulator events to clients.
+
+ See Documentation/power/regulator/regulator.txt
+
+ 3. Machine interface.
+
+ This interface is for machine specific code and allows the creation of
+ voltage/current domains (with constraints) for each regulator. It can
+ provide regulator constraints that will prevent device damage through
+ overvoltage or over current caused by buggy client drivers. It also
+ allows the creation of a regulator tree whereby some regulators are
+ supplied by others (similar to a clock tree).
+
+ See Documentation/power/regulator/machine.txt
+
+ 4. Userspace ABI.
+
+ The framework also exports a lot of useful voltage/current/opmode data to
+ userspace via sysfs. This could be used to help monitor device power
+ consumption and status.
+
+ See Documentation/ABI/testing/regulator-sysfs.txt
diff --git a/Documentation/power/regulator/regulator.txt b/Documentation/power/regulator/regulator.txt
new file mode 100644
index 000000000000..a69050143592
--- /dev/null
+++ b/Documentation/power/regulator/regulator.txt
@@ -0,0 +1,30 @@
+Regulator Driver Interface
+==========================
+
+The regulator driver interface is relatively simple and designed to allow
+regulator drivers to register their services with the core framework.
+
+
+Registration
+============
+
+Drivers can register a regulator by calling :-
+
+struct regulator_dev *regulator_register(struct regulator_desc *regulator_desc,
+ void *reg_data);
+
+This will register the regulators capabilities and operations the regulator
+core. The core does not touch reg_data (private to regulator driver).
+
+Regulators can be unregistered by calling :-
+
+void regulator_unregister(struct regulator_dev *rdev);
+
+
+Regulator Events
+================
+Regulators can send events (e.g. over temp, under voltage, etc) to consumer
+drivers by calling :-
+
+int regulator_notifier_call_chain(struct regulator_dev *rdev,
+ unsigned long event, void *data);