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Driver Entry Points

power(9E)

INTERFACE LEVEL
PARAMETERS
DESCRIPTION
RETURN VALUES
CONTEXT
ATTRIBUTES
SEE ALSO

NAME

power - power a device attached to the system

SYNOPSIS

#include <sys/ddi.h> #include <sys/sunddi.h> int prefixpower(dev_info_t *dip, int component, int level);

INTERFACE LEVEL

Solaris DDI specific (Solaris DDI). This entry point is required. If the driver writer does not supply this entry point, the value NULL must be used in the cb_ops(9S) structure instead.

PARAMETERS

dip: Pointer to the device's dev_info structure.
component: Component of the driver to be managed.
level: Desired component power level.

DESCRIPTION

The power(9e) function is the device-specific Power Management entry point. This function is called when the system wants the driver to set the power level of component to level.

The power() entry points behave as described under NEW BEHAVIOR if the device driver uses new automatic device Power Management interfaces (driver exports pm-components(9P) property). The power()entry point behaves as described under OBSOLETE BEHAVIOR if the device driver uses original Power Management interfaces (driver does not export the pm-components property but instead calls pm_create_components(9F)). The behavior described under OBSOLETE BEHAVIOR is obsolete and will be removed in a future release.

NEW BEHAVIOR

The level argument is the driver-defined power level to which the component needs to be set. Except for power level 0, which is interpreted by the framework to mean "powered off," the interpretation of level is entirely up to the driver.

The component argument is the component of the device to be power-managed. The interpretation of component is entirely up to the driver.

When a requested power transition would cause the device to lose state, the driver must save the state of the device in memory. When a requested power transition requires state to be restored, the driver must restore that state.

If a requested power transition for one component requires another component to change power state before it can be completed, the driver must call pm_raise_power(9f) to get the other component changed, and the power(9e) entry point must support being re-entered.

If the system requests an inappropriate power transition for the device (for example, a request to power down a device which has just become busy), then the power level should not be changed and power should return DDI_FAILURE.

OBSOLETE BEHAVIOR

The level argument is the driver-defined power level to which component must be set. Except for power level 0 which is defined by the framework to mean "powered off," the interpretation of level is entirely up to the driver.

The component argument is the component of the device to be power-managed. Except for component 0, which must represent the entire device, the interpretation of component is entirely up to the driver.

The power() function can assume that the driver will be suspended (using detach(9E) with command DDI_PM_SUSPEND), before a request is made to set component 0 to power level 0 and resumed (using attach(9E) with command DDI_PM_RESUME) after setting component 0 from power level 0 to a non-zero power level.

RETURN VALUES

The power() function returns:

DDI_SUCCESS: Successfully set the power to the requested level.
DDI_FAILURE: Failed to set the power to the requested level.

CONTEXT

The power() function is called from user or kernel context only.

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Interface stability	Evolving (Interfaces under OBSOLETE BEHAVIOR are obsolete.)