Messages in this thread | | | From | Paulius Zaleckas <> | Subject | Re: [PATCH 10/15] regulator: documentation - consumer interface | Date | Fri, 11 Jul 2008 18:10:13 +0300 |
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Liam Girdwood wrote: > This adds documentation describing the consumer device interface. > > Signed-off-by: Liam Girdwood <lg@opensource.wolfsonmicro.com> > --- > Documentation/power/regulator/consumer.txt | 182 ++++++++++++++++++++++++++++ > 1 files changed, 182 insertions(+), 0 deletions(-) > create mode 100644 Documentation/power/regulator/consumer.txt > > diff --git a/Documentation/power/regulator/consumer.txt b/Documentation/power/regulator/consumer.txt > new file mode 100644 > index 0000000..9ea688d > --- /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 initialisation code.
initialization ^ > + > +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 > +determind the regulator physical output voltage.
determine ^ > + > + > +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.
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