9 files changed, 528 insertions, 260 deletions

diff --git a/Documentation/power/00-INDEX b/Documentation/power/00-INDEX
index a55d7f1c836d..fb742c213c9e 100644
--- a/Documentation/power/00-INDEX
+++ b/Documentation/power/00-INDEX
@@ -1,5 +1,7 @@
 00-INDEX
         - This file
+apm-acpi.txt
+        - basic info about the APM and ACPI support.
 basic-pm-debugging.txt
         - Debugging suspend and resume
 devices.txt
@@ -14,8 +16,6 @@ notifiers.txt
         - Registering suspend notifiers in device drivers
 pci.txt
         - How the PCI Subsystem Does Power Management
-pm.txt
-        - info on Linux power management support.
 pm_qos_interface.txt
         - info on Linux PM Quality of Service interface
 power_supply_class.txt
diff --git a/Documentation/power/apm-acpi.txt b/Documentation/power/apm-acpi.txt
new file mode 100644
index 000000000000..1bd799dc17e8
--- /dev/null
+++ b/Documentation/power/apm-acpi.txt
@@ -0,0 +1,32 @@
+APM or ACPI?
+------------
+If you have a relatively recent x86 mobile, desktop, or server system,
+odds are it supports either Advanced Power Management (APM) or
+Advanced Configuration and Power Interface (ACPI).  ACPI is the newer
+of the two technologies and puts power management in the hands of the
+operating system, allowing for more intelligent power management than
+is possible with BIOS controlled APM.
+
+The best way to determine which, if either, your system supports is to
+build a kernel with both ACPI and APM enabled (as of 2.3.x ACPI is
+enabled by default).  If a working ACPI implementation is found, the
+ACPI driver will override and disable APM, otherwise the APM driver
+will be used.
+
+No, sorry, you cannot have both ACPI and APM enabled and running at
+once.  Some people with broken ACPI or broken APM implementations
+would like to use both to get a full set of working features, but you
+simply cannot mix and match the two.  Only one power management
+interface can be in control of the machine at once.  Think about it..
+
+User-space Daemons
+------------------
+Both APM and ACPI rely on user-space daemons, apmd and acpid
+respectively, to be completely functional.  Obtain both of these
+daemons from your Linux distribution or from the Internet (see below)
+and be sure that they are started sometime in the system boot process.
+Go ahead and start both.  If ACPI or APM is not available on your
+system the associated daemon will exit gracefully.
+
+  apmd:   http://worldvisions.ca/~apenwarr/apmd/
+  acpid:  http://acpid.sf.net/
diff --git a/Documentation/power/pm.txt b/Documentation/power/pm.txt
deleted file mode 100644
index be841507e43f..000000000000
--- a/Documentation/power/pm.txt
+++ /dev/null
@@ -1,257 +0,0 @@
-               Linux Power Management Support
-
-This document briefly describes how to use power management with your
-Linux system and how to add power management support to Linux drivers.
-
-APM or ACPI?
-------------
-If you have a relatively recent x86 mobile, desktop, or server system,
-odds are it supports either Advanced Power Management (APM) or
-Advanced Configuration and Power Interface (ACPI).  ACPI is the newer
-of the two technologies and puts power management in the hands of the
-operating system, allowing for more intelligent power management than
-is possible with BIOS controlled APM.
-
-The best way to determine which, if either, your system supports is to
-build a kernel with both ACPI and APM enabled (as of 2.3.x ACPI is
-enabled by default).  If a working ACPI implementation is found, the
-ACPI driver will override and disable APM, otherwise the APM driver
-will be used.
-
-No, sorry, you cannot have both ACPI and APM enabled and running at
-once.  Some people with broken ACPI or broken APM implementations
-would like to use both to get a full set of working features, but you
-simply cannot mix and match the two.  Only one power management
-interface can be in control of the machine at once.  Think about it..
-
-User-space Daemons
-------------------
-Both APM and ACPI rely on user-space daemons, apmd and acpid
-respectively, to be completely functional.  Obtain both of these
-daemons from your Linux distribution or from the Internet (see below)
-and be sure that they are started sometime in the system boot process.
-Go ahead and start both.  If ACPI or APM is not available on your
-system the associated daemon will exit gracefully.
-
-  apmd:   http://worldvisions.ca/~apenwarr/apmd/
-  acpid:  http://acpid.sf.net/
-
-Driver Interface -- OBSOLETE, DO NOT USE!
-----------------*************************
-
-Note: pm_register(), pm_access(), pm_dev_idle() and friends are
-obsolete. Please do not use them. Instead you should properly hook
-your driver into the driver model, and use its suspend()/resume()
-callbacks to do this kind of stuff.
-
-If you are writing a new driver or maintaining an old driver, it
-should include power management support.  Without power management
-support, a single driver may prevent a system with power management
-capabilities from ever being able to suspend (safely).
-
-Overview:
-1) Register each instance of a device with "pm_register"
-2) Call "pm_access" before accessing the hardware.
-   (this will ensure that the hardware is awake and ready)
-3) Your "pm_callback" is called before going into a
-   suspend state (ACPI D1-D3) or after resuming (ACPI D0)
-   from a suspend.
-4) Call "pm_dev_idle" when the device is not being used
-   (optional but will improve device idle detection)
-5) When unloaded, unregister the device with "pm_unregister"
-
-/*
- * Description: Register a device with the power-management subsystem
- *
- * Parameters:
- *   type - device type (PCI device, system device, ...)
- *   id - instance number or unique identifier
- *   cback - request handler callback (suspend, resume, ...)
- *
- * Returns: Registered PM device or NULL on error
- *
- * Examples:
- *   dev = pm_register(PM_SYS_DEV, PM_SYS_VGA, vga_callback);
- *
- *   struct pci_dev *pci_dev = pci_find_dev(...);
- *   dev = pm_register(PM_PCI_DEV, PM_PCI_ID(pci_dev), callback);
- */
-struct pm_dev *pm_register(pm_dev_t type, unsigned long id, pm_callback cback);
-
-/*
- * Description: Unregister a device with the power management subsystem
- *
- * Parameters:
- *   dev - PM device previously returned from pm_register
- */
-void pm_unregister(struct pm_dev *dev);
-
-/*
- * Description: Unregister all devices with a matching callback function
- *
- * Parameters:
- *   cback - previously registered request callback
- *
- * Notes: Provided for easier porting from old APM interface
- */
-void pm_unregister_all(pm_callback cback);
-
-/*
- * Power management request callback
- *
- * Parameters:
- *   dev - PM device previously returned from pm_register
- *   rqst - request type
- *   data - data, if any, associated with the request
- *
- * Returns: 0 if the request is successful
- *          EINVAL if the request is not supported
- *          EBUSY if the device is now busy and cannot handle the request
- *          ENOMEM if the device was unable to handle the request due to memory
- *
- * Details: The device request callback will be called before the
- *          device/system enters a suspend state (ACPI D1-D3) or
- *          or after the device/system resumes from suspend (ACPI D0).
- *          For PM_SUSPEND, the ACPI D-state being entered is passed
- *          as the "data" argument to the callback.  The device
- *          driver should save (PM_SUSPEND) or restore (PM_RESUME)
- *          device context when the request callback is called.
- *
- *          Once a driver returns 0 (success) from a suspend
- *          request, it should not process any further requests or
- *          access the device hardware until a call to "pm_access" is made.
- */
-typedef int (*pm_callback)(struct pm_dev *dev, pm_request_t rqst, void *data);
-
-Driver Details
---------------
-This is just a quick Q&A as a stopgap until a real driver writers'
-power management guide is available.
-
-Q: When is a device suspended?
-
-Devices can be suspended based on direct user request (eg. laptop lid
-closes), system power policy (eg.  sleep after 30 minutes of console
-inactivity), or device power policy (eg. power down device after 5
-minutes of inactivity)
-
-Q: Must a driver honor a suspend request?
-
-No, a driver can return -EBUSY from a suspend request and this
-will stop the system from suspending.  When a suspend request
-fails, all suspended devices are resumed and the system continues
-to run.  Suspend can be retried at a later time.
-
-Q: Can the driver block suspend/resume requests?
-
-Yes, a driver can delay its return from a suspend or resume
-request until the device is ready to handle requests.  It
-is advantageous to return as quickly as possible from a
-request as suspend/resume are done serially.
-
-Q: What context is a suspend/resume initiated from?
-
-A suspend or resume is initiated from a kernel thread context.
-It is safe to block, allocate memory, initiate requests
-or anything else you can do within the kernel.
-
-Q: Will requests continue to arrive after a suspend?
-
-Possibly.  It is the driver's responsibility to queue(*),
-fail, or drop any requests that arrive after returning
-success to a suspend request.  It is important that the
-driver not access its device until after it receives
-a resume request as the device's bus may no longer
-be active.
-
-(*) If a driver queues requests for processing after
-    resume be aware that the device, network, etc.
-    might be in a different state than at suspend time.
-    It's probably better to drop requests unless
-    the driver is a storage device.
-
-Q: Do I have to manage bus-specific power management registers
-
-No.  It is the responsibility of the bus driver to manage
-PCI, USB, etc. power management registers.  The bus driver
-or the power management subsystem will also enable any
-wake-on functionality that the device has.
-
-Q: So, really, what do I need to do to support suspend/resume?
-
-You need to save any device context that would
-be lost if the device was powered off and then restore
-it at resume time.  When ACPI is active, there are
-three levels of device suspend states; D1, D2, and D3.
-(The suspend state is passed as the "data" argument
-to the device callback.)  With D3, the device is powered
-off and loses all context, D1 and D2 are shallower power
-states and require less device context to be saved.  To
-play it safe, just save everything at suspend and restore
-everything at resume.
-
-Q: Where do I store device context for suspend?
-
-Anywhere in memory, kmalloc a buffer or store it
-in the device descriptor.  You are guaranteed that the
-contents of memory will be restored and accessible
-before resume, even when the system suspends to disk.
-
-Q: What do I need to do for ACPI vs. APM vs. etc?
-
-Drivers need not be aware of the specific power management
-technology that is active.  They just need to be aware
-of when the overlying power management system requests
-that they suspend or resume.
-
-Q: What about device dependencies?
-
-When a driver registers a device, the power management
-subsystem uses the information provided to build a
-tree of device dependencies (eg. USB device X is on
-USB controller Y which is on PCI bus Z)  When power
-management wants to suspend a device, it first sends
-a suspend request to its driver, then the bus driver,
-and so on up to the system bus.  Device resumes
-proceed in the opposite direction.
-
-Q: Who do I contact for additional information about
-   enabling power management for my specific driver/device?
-
-ACPI Development mailing list: linux-acpi@vger.kernel.org
-
-System Interface -- OBSOLETE, DO NOT USE!
-----------------*************************
-If you are providing new power management support to Linux (ie.
-adding support for something like APM or ACPI), you should
-communicate with drivers through the existing generic power
-management interface.
-
-/*
- * Send a request to all devices
- *
- * Parameters:
- *   rqst - request type
- *   data - data, if any, associated with the request
- *
- * Returns: 0 if the request is successful
- *          See "pm_callback" return for errors
- *
- * Details: Walk list of registered devices and call pm_send
- *          for each until complete or an error is encountered.
- *          If an error is encountered for a suspend request,
- *          return all devices to the state they were in before
- *          the suspend request.
- */
-int pm_send_all(pm_request_t rqst, void *data);
-
-/*
- * Find a matching device
- *
- * Parameters:
- *   type - device type (PCI device, system device, or 0 to match all devices)
- *   from - previous match or NULL to start from the beginning
- *
- * Returns: Matching device or NULL if none found
- */
-struct pm_dev *pm_find(pm_dev_t type, struct pm_dev *from);
diff --git a/Documentation/power/pm_qos_interface.txt b/Documentation/power/pm_qos_interface.txt
index 49adb1a33514..c40866e8b957 100644
--- a/Documentation/power/pm_qos_interface.txt
+++ b/Documentation/power/pm_qos_interface.txt
@@ -1,4 +1,4 @@
-PM quality of Service interface.
+PM Quality Of Service Interface.
 
 This interface provides a kernel and user mode interface for registering
 performance expectations by drivers, subsystems and user space applications on
@@ -7,6 +7,11 @@ one of the parameters.
 Currently we have {cpu_dma_latency, network_latency, network_throughput} as the
 initial set of pm_qos parameters.
 
+Each parameters have defined units:
+ * latency: usec
+ * timeout: usec
+ * throughput: kbs (kilo bit / sec)
+
 The infrastructure exposes multiple misc device nodes one per implemented
 parameter.  The set of parameters implement is defined by pm_qos_power_init()
 and pm_qos_params.h.  This is done because having the available parameters
diff --git a/Documentation/power/power_supply_class.txt b/Documentation/power/power_supply_class.txt
index a8686e5a6857..c6cd4956047c 100644
--- a/Documentation/power/power_supply_class.txt
+++ b/Documentation/power/power_supply_class.txt
@@ -101,6 +101,10 @@ of charge when battery became full/empty". It also could mean "value of
 charge when battery considered full/empty at given conditions (temperature,
 age)". I.e. these attributes represents real thresholds, not design values.
 
+CHARGE_COUNTER - the current charge counter (in µAh).  This could easily
+be negative; there is no empty or full value.  It is only useful for
+relative, time-based measurements.
+
 ENERGY_FULL, ENERGY_EMPTY - same as above but for energy.
 
 CAPACITY - capacity in percents.
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);