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)
