Kernel Functions for Drivers pm_raise_power(9F)
NAME
pm_raise_power, pm_lower_power - Raise or lower power of
componentsSYNOPSIS
#include
#include
int pm_raise_power(dev_info_t *dip, int component, int level);
int pm_lower_power(dev_info_t *dip, int component, int level);
INTERFACE LEVEL
Solaris DDI specific (Solaris DDI)PARAMETERS
pm_raise_power
dip Pointer to the device's dev_info structure
component The number of the component for which a power level change is desiredlevel The power level to which the indicated com-
ponent will be raisedpm_lower_power
dip Pointer to the device's dev_info structure
component Number of the component for which a power level change is desired level Power level to which the indicated component will be loweredDESCRIPTION
The pm_raise_power(9F) function requests the Power Manage-
ment framework to raise the power level of component of dip to at least level.The state of the device should be examined before each phy-
sical access. The pm_raise_power(9F) function should be
called to set a component to the required power level if the operation to be performed requires the component to beSunOS 5.11 Last change: 22 March 2005 1
Kernel Functions for Drivers pm_raise_power(9F)
at a power level higher than its current power level.When pm_raise_power(9F) returns with success, the component
is guaranteed to be at least at the requested power level. All devices that depend on this will be at their full power level. Since the actual device power level may be higher than requested by the driver, the driver should not make any assumption about the absolute power level on successfulreturn from pm_raise_power(9F).
The pm_raise_power(9F) function may cause re-entry of the
driver power(9E) to raise the power level. Deadlock may result if the driver locks are held across the call topm_raise_power(9F).
The pm_lower_power(9F) function requests the Power Manage-
ment framework to lower the power level of component of dip to at most level. Normally, transitions to lower power levels are initiated by the Power Management framework based on component idleness. However, when detaching, the driver should also initiatereduced power levels by setting the power level of all dev-
ice components to their lowest levels. Thepm_lower_power(9F) function is intended for this use only,
and will return DDI_FAILURE if the driver is not detaching
at the time of the call. If automatic Power Management is disabled (see dtpower(1M)and power.conf(4)), pm_lower_power(9F) returns DDI_SUCCESS
without changing the power level of the component. Other-
wise, when pm_lower_power(9F) returns with success, the com-
ponent is guaranteed to be at most at the requested power level. Since the actual device power level may be lower than requested by the driver, the driver should not make any assumption about the absolute power level on successfulreturn from pm_lower_power(9F).
The pm_lower_power(9F) function may cause re-entry of the
driver power(9E) to lower the power level. Deadlock may result if the driver locks are held across the call topm_lower_power(9F).
Note -
If these functions are called as a result of entry intoSunOS 5.11 Last change: 22 March 2005 2
Kernel Functions for Drivers pm_raise_power(9F)
the driver's attach(9E), detach(9E) or power(9E) entry point, these functions must be called from the same thread which entered attach(9E), detach(9E) or power(9E).RETURN VALUES
The pm_raise_power(9F) function returns:
DDI_SUCCESS Component is now at the requested power level
or higher.DDI_FAILURE Component or level is out of range, or the
framework was unable to raise the power level of the component to the requested level.The pm_lower_power(9F) function returns:
DDI_SUCCESS Component is now at the requested power
level or lower, or automatic Power Management is disabled.DDI_FAILURE Component or level is out of range, or the
framework was unable to lower the power level of the component to the requested level, or the device is not detaching.EXAMPLES
A hypothetical disk driver might include this code to handlepm_raise_power(9F):
static intxxdisk_strategy(struct buf *bp)
{ ... /* * At this point we have determined that we need to raise the * power level of the device. Since we have to drop the * mutex, we need to take care of case where framework is * lowering power at the same time we are raising power. * We resolve this by marking the device busy and failing * lower power in power() entry point when device is busy. */ASSERT(mutex_owned(xsp->lock));
if (xsp->pm_busycnt < 1) {
/*SunOS 5.11 Last change: 22 March 2005 3
Kernel Functions for Drivers pm_raise_power(9F)
* Component is not already marked busy */if (pm_busy_component(xsp->dip,
XXDISK_COMPONENT) != DDI_SUCCESS) {
bioerror(bp,EIO); biodone(bp); return (0); }xsp->pm_busycnt++;
}mutex_exit(xsp->lock);
if (pm_raise_power(xsp->dip,
XXDISK_COMPONENT, XXPOWER_SPUN_UP) != DDI_SUCCESS) {
bioerror(bp,EIO); biodone(bp); return (0); }mutex_enter(xsp->lock);
.... }xxdisk_power(dev_info *dip, int comp, int level)
{ ... /* * We fail the power() entry point if the device is busy and * request is to lower the power level. */ASSERT(mutex_owned( xsp->lock));
if (xsp->pm_busycnt >= 1) {
if (level < xsp->cur_level) {
mutex_exit( xsp->lock);
return (DDI_FAILURE);
} } ... }CONTEXT
These functions can be called from user or kernel context.SunOS 5.11 Last change: 22 March 2005 4
Kernel Functions for Drivers pm_raise_power(9F)
ATTRIBUTES
See attributes(5) for a description of the following attri-
bute:____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Interface Stability | Committed ||_____________________________|_____________________________|
SEE ALSO
power.conf(4), pm(7D), attach(9E), detach(9E), power(9E),pm_busy_component(9F), pm_idle_component(9F), pm(9P), pm-
components(9P) Writing Device DriversSunOS 5.11 Last change: 22 March 2005 5