POWER(9E) Driver Entry Points POWER(9E)

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

illumos DDI specific (illumos DDI). This entry point is required. If the
driver writer does not supply this entry point, the value NULL must be
used in the dev_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 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.

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(7) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface stability | Committed |
+--------------------+-----------------+

SEE ALSO

attach(9E), detach(9E), pm_busy_component(9F), pm_idle_component(9F),
pm_raise_power(9F), dev_ops(9S)


Writing Device Drivers


Using Power Management

September 16, 2016 POWER(9E)