Copyright © 2007-2008 Wolfson Microelectronics
Copyright © 2008 Liam Girdwood
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.
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.
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
For more details see the file COPYING in the source distribution of Linux.
Table of Contents
regulator_list_voltage selectors
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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.
The regulator API uses a number of terms which may not be familiar:
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.
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.
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.
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.
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This offers a similar API to the kernel clock framework. Consumer drivers use get and put operations to acquire and release regulators. Functions are provided to enable and disable the reguator 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.
The regulator API provides reference counted enabling and
disabling of regulators. Consumer devices use the regulator_enable
and 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
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.
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 regulator_set_voltage
and 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 may also be registered for events such as regulation failures.
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 regulator_init_data for the regulator containing constraint and supply information.
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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.
Regulator supplies are specified using struct regulator_consumer_supply. This is done at driver registration time as part of the machine constraints.
As well as definining the connections the machine interface also provides constraints definining 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 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.
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regulator_list_voltage selectors
Due to limitations of the kernel documentation framework and the existing layout of the source code the entire regulator API is documented here.
struct regulator_bulk_data — Data used for bulk regulator operations.
struct regulator_bulk_data {
const char * supply;
struct regulator * consumer;
}; struct regulator_state — regulator state during low power system states
struct regulator_state {
int uV;
unsigned int mode;
int enabled;
}; struct regulation_constraints — regulator operating constraints.
struct regulation_constraints {
char * name;
int min_uV;
int max_uV;
int min_uA;
int max_uA;
unsigned int valid_modes_mask;
unsigned int valid_ops_mask;
int input_uV;
struct regulator_state state_disk;
struct regulator_state state_mem;
struct regulator_state state_standby;
suspend_state_t initial_state;
unsigned int initial_mode;
unsigned always_on:1;
unsigned boot_on:1;
unsigned apply_uV:1;
}; Descriptive name for the constraints, used for display purposes.
Smallest voltage consumers may set.
Largest voltage consumers may set.
Smallest consumers consumers may set.
Largest current consumers may set.
Mask of modes which may be configured by consumers.
Operations which may be performed by consumers.
Input voltage for regulator when supplied by another regulator.
State for regulator when system is suspended in disk mode.
State for regulator when system is suspended in mem mode.
State for regulator when system is suspended in standby mode.
Suspend state to set by default.
Mode to set at startup.
Set if the regulator should never be disabled.
Set if the regulator is enabled when the system is initially started. If the regulator is not enabled by the hardware or bootloader then it will be enabled when the constraints are applied.
Apply the voltage constraint when initialising.
struct regulator_consumer_supply — supply -> device mapping
struct regulator_consumer_supply {
struct device * dev;
const char * dev_name;
const char * supply;
}; struct regulator_init_data — regulator platform initialisation data.
struct regulator_init_data {
struct device * supply_regulator_dev;
struct regulation_constraints constraints;
int num_consumer_supplies;
struct regulator_consumer_supply * consumer_supplies;
int (* regulator_init) (void *driver_data);
void * driver_data;
}; Parent regulator (if any).
Constraints. These must be specified for the regulator to be usable.
Number of consumer device supplies.
Consumer device supply configuration.
Callback invoked when the regulator has been registered.
Data passed to regulator_init.
struct regulator_ops — regulator operations.
struct regulator_ops {
int (* list_voltage) (struct regulator_dev *, unsigned selector);
int (* set_voltage) (struct regulator_dev *, int min_uV, int max_uV);
int (* get_voltage) (struct regulator_dev *);
int (* set_current_limit) (struct regulator_dev *,int min_uA, int max_uA);
int (* get_current_limit) (struct regulator_dev *);
int (* enable) (struct regulator_dev *);
int (* disable) (struct regulator_dev *);
int (* is_enabled) (struct regulator_dev *);
int (* set_mode) (struct regulator_dev *, unsigned int mode);
unsigned int (* get_mode) (struct regulator_dev *);
int (* get_status) (struct regulator_dev *);
unsigned int (* get_optimum_mode) (struct regulator_dev *, int input_uV,int output_uV, int load_uA);
int (* set_suspend_voltage) (struct regulator_dev *, int uV);
int (* set_suspend_enable) (struct regulator_dev *);
int (* set_suspend_disable) (struct regulator_dev *);
int (* set_suspend_mode) (struct regulator_dev *, unsigned int mode);
}; Return one of the supported voltages, in microvolts; zero if the selector indicates a voltage that is unusable on this system; or negative errno. Selectors range from zero to one less than regulator_desc.n_voltages. Voltages may be reported in any order.
Set the voltage for the regulator within the range specified. The driver should select the voltage closest to min_uV.
Return the currently configured voltage for the regulator.
Configure a limit for a current-limited regulator.
Get the configured limit for a current-limited regulator.
Configure the regulator as enabled.
Configure the regulator as disabled.
Return 1 if the regulator is enabled, 0 if not. May also return negative errno.
Set the configured operating mode for the regulator.
Get the configured operating mode for the regulator.
Return actual (not as-configured) status of regulator, as a REGULATOR_STATUS value (or negative errno)
Get the most efficient operating mode for the regulator when running with the specified parameters.
Set the voltage for the regulator when the system is suspended.
Mark the regulator as enabled when the system is suspended.
Mark the regulator as disabled when the system is suspended.
Set the operating mode for the regulator when the system is suspended.
struct regulator_desc — Regulator descriptor
struct regulator_desc {
const char * name;
int id;
unsigned n_voltages;
struct regulator_ops * ops;
int irq;
enum regulator_type type;
struct module * owner;
}; Identifying name for the regulator.
Numerical identifier for the regulator.
Number of selectors available for ops.list_voltage.
Regulator operations table.
Interrupt number for the regulator.
Indicates if the regulator is a voltage or current regulator.
Module providing the regulator, used for refcounting.
regulator_get — lookup and obtain a reference to a regulator.
struct regulator * regulator_get ( | dev, | |
id); |
struct device * | dev; |
const char * | id; |
Returns a struct regulator corresponding to the regulator producer,
or IS_ERR condition containing errno.
Use of supply names configured via regulator_set_device_supply is
strongly encouraged. It is recommended that the supply name used
should match the name used for the supply and/or the relevant
device pins in the datasheet.
regulator_get_exclusive — obtain exclusive access to a regulator.
struct regulator * regulator_get_exclusive ( | dev, | |
id); |
struct device * | dev; |
const char * | id; |
Returns a struct regulator corresponding to the regulator producer,
or IS_ERR condition containing errno. Other consumers will be
unable to obtain this reference is held and the use count for the
regulator will be initialised to reflect the current state of the
regulator.
This is intended for use by consumers which cannot tolerate shared use of the regulator such as those which need to force the regulator off for correct operation of the hardware they are controlling.
Use of supply names configured via regulator_set_device_supply is
strongly encouraged. It is recommended that the supply name used
should match the name used for the supply and/or the relevant
device pins in the datasheet.
regulator_put — "free" the regulator source
void regulator_put ( | regulator); |
struct regulator * | regulator; |
regulator_enable — enable regulator output
int regulator_enable ( | regulator); |
struct regulator * | regulator; |
regulator_disable — disable regulator output
int regulator_disable ( | regulator); |
struct regulator * | regulator; |
regulator_force_disable — force disable regulator output
int regulator_force_disable ( | regulator); |
struct regulator * | regulator; |
regulator_is_enabled — is the regulator output enabled
int regulator_is_enabled ( | regulator); |
struct regulator * | regulator; |
Returns positive if the regulator driver backing the source/client has requested that the device be enabled, zero if it hasn't, else a negative errno code.
Note that the device backing this regulator handle can have multiple
users, so it might be enabled even if regulator_enable was never
called for this particular source.
regulator_count_voltages —
count regulator_list_voltage selectors
int regulator_count_voltages ( | regulator); |
struct regulator * | regulator; |
regulator_list_voltage — enumerate supported voltages
int regulator_list_voltage ( | regulator, | |
selector); |
struct regulator * | regulator; |
unsigned | selector; |
regulator_set_voltage — set regulator output voltage
int regulator_set_voltage ( | regulator, | |
| min_uV, | ||
max_uV); |
struct regulator * | regulator; |
int | min_uV; |
int | max_uV; |
regulatorregulator source
min_uVMinimum required voltage in uV
max_uVMaximum acceptable voltage in uV
Sets a voltage regulator to the desired output voltage. This can be set during any regulator state. IOW, regulator can be disabled or enabled.
If the regulator is enabled then the voltage will change to the new value immediately otherwise if the regulator is disabled the regulator will output at the new voltage when enabled.
regulator_get_voltage — get regulator output voltage
int regulator_get_voltage ( | regulator); |
struct regulator * | regulator; |
regulator_set_current_limit — set regulator output current limit
int regulator_set_current_limit ( | regulator, | |
| min_uA, | ||
max_uA); |
struct regulator * | regulator; |
int | min_uA; |
int | max_uA; |
regulatorregulator source
min_uAMinimuum supported current in uA
max_uAMaximum supported current in uA
Sets current sink to the desired output current. This can be set during any regulator state. IOW, regulator can be disabled or enabled.
If the regulator is enabled then the current will change to the new value immediately otherwise if the regulator is disabled the regulator will output at the new current when enabled.
regulator_get_current_limit — get regulator output current
int regulator_get_current_limit ( | regulator); |
struct regulator * | regulator; |
regulator_set_mode — set regulator operating mode
int regulator_set_mode ( | regulator, | |
mode); |
struct regulator * | regulator; |
unsigned int | mode; |
regulator_get_mode — get regulator operating mode
unsigned int regulator_get_mode ( | regulator); |
struct regulator * | regulator; |
regulator_set_optimum_mode — set regulator optimum operating mode
int regulator_set_optimum_mode ( | regulator, | |
uA_load); |
struct regulator * | regulator; |
int | uA_load; |
Notifies the regulator core of a new device load. This is then used by DRMS (if enabled by constraints) to set the most efficient regulator operating mode for the new regulator loading.
Consumer devices notify their supply regulator of the maximum power they will require (can be taken from device datasheet in the power consumption tables) when they change operational status and hence power state. Examples of operational state changes that can affect power
-
o Device is opened / closed. o Device I/O is about to begin or has just finished. o Device is idling in between work.
This information is also exported via sysfs to userspace.
DRMS will sum the total requested load on the regulator and change to the most efficient operating mode if platform constraints allow.
Returns the new regulator mode or error.
regulator_register_notifier — register regulator event notifier
int regulator_register_notifier ( | regulator, | |
nb); |
struct regulator * | regulator; |
struct notifier_block * | nb; |
regulator_unregister_notifier — unregister regulator event notifier
int regulator_unregister_notifier ( | regulator, | |
nb); |
struct regulator * | regulator; |
struct notifier_block * | nb; |
regulator_bulk_get — get multiple regulator consumers
int regulator_bulk_get ( | dev, | |
| num_consumers, | ||
consumers); |
struct device * | dev; |
int | num_consumers; |
struct regulator_bulk_data * | consumers; |
regulator_bulk_enable — enable multiple regulator consumers
int regulator_bulk_enable ( | num_consumers, | |
consumers); |
int | num_consumers; |
struct regulator_bulk_data * | consumers; |
regulator_bulk_disable — disable multiple regulator consumers
int regulator_bulk_disable ( | num_consumers, | |
consumers); |
int | num_consumers; |
struct regulator_bulk_data * | consumers; |
regulator_bulk_free — free multiple regulator consumers
void regulator_bulk_free ( | num_consumers, | |
consumers); |
int | num_consumers; |
struct regulator_bulk_data * | consumers; |
regulator_notifier_call_chain — call regulator event notifier
int regulator_notifier_call_chain ( | rdev, | |
| event, | ||
data); |
struct regulator_dev * | rdev; |
unsigned long | event; |
void * | data; |
regulator_mode_to_status — convert a regulator mode into a status
int regulator_mode_to_status ( | mode); |
unsigned int | mode; |
regulator_register — register regulator
struct regulator_dev * regulator_register ( | regulator_desc, | |
| dev, | ||
| init_data, | ||
driver_data); |
struct regulator_desc * | regulator_desc; |
struct device * | dev; |
struct regulator_init_data * | init_data; |
void * | driver_data; |
regulator_unregister — unregister regulator
void regulator_unregister ( | rdev); |
struct regulator_dev * | rdev; |
regulator_suspend_prepare — prepare regulators for system wide suspend
int regulator_suspend_prepare ( | state); |
suspend_state_t | state; |
regulator_has_full_constraints — the system has fully specified constraints
void regulator_has_full_constraints ( | void); |
| void; |
Calling this function will cause the regulator API to disable all regulators which have a zero use count and don't have an always_on constraint in a late_initcall.
The intention is that this will become the default behaviour in a future kernel release so users are encouraged to use this facility now.
rdev_get_drvdata — get rdev regulator driver data
void * rdev_get_drvdata ( | rdev); |
struct regulator_dev * | rdev; |
regulator_get_drvdata — get regulator driver data
void * regulator_get_drvdata ( | regulator); |
struct regulator * | regulator; |