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

       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  level   argument  is  the driver-defined power level to which the component needs to be set. Except for power level 0, which is inter-
       preted 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(5) for descriptions of the following attributes:

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

SEE ALSO

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

       Writing Device Drivers

	Using Power Management

SunOS 5.10							    12 Dec 2003 							 power(9E)