Leaked source code of windows server 2003
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/*++
Copyright (c) 1990 Microsoft Corporation
Module Name:
state.c
Abstract:
Maintains state changes for power management power states
for device objects
Author:
Ken Reneris (kenr) 19-July-1994
Revision History:
--*/
#include "pop.h"
// sync rules - only PoSetPowerState ever writes to the
// StateValue entries in the psb.
//
NTKERNELAPI
POWER_STATE
PoSetPowerState (
IN PDEVICE_OBJECT DeviceObject,
IN POWER_STATE_TYPE Type,
IN POWER_STATE State
)
/*++
Routine Description:
This routine stores the new power state for a device object,
calling notification routines, if any, first.
If the new state and old state are the same, this procedure
is a noop
A note on synchronization:
No lock is acquire just to set the values. This is because
it is assumed that only this routine writes them, so locking
is not necessary.
If the notify list is to be run, a lock will be acquired.
Arguments:
DeviceObject - pointer to the device object to set the power
state for and to issue any notifications for
Type - indicates whether System or Device state is being set
State - the System or Device state to set
Return Value:
The Old power state.
--*/
{
PDEVOBJ_EXTENSION doe;
PDEVICE_OBJECT_POWER_EXTENSION dope;
POWER_STATE OldState;
BOOLEAN change;
ULONG notificationmask;
KIRQL OldIrql2;
ASSERT(KeGetCurrentIrql() <= DISPATCH_LEVEL);
ASSERT(DeviceObject);
PoPowerTrace(POWERTRACE_SETSTATE,DeviceObject,(ULONG)Type,(ULONG)State.SystemState);
doe = DeviceObject->DeviceObjectExtension;
dope = doe->Dope;
notificationmask = 0L;
change = FALSE;
PopLockIrpSerialList(&OldIrql2);
switch (Type) {
case SystemPowerState:
OldState.SystemState = PopGetDoSystemPowerState(doe);
if (OldState.SystemState != State.SystemState) {
change = TRUE;
}
break;
case DevicePowerState:
OldState.DeviceState = PopGetDoDevicePowerState(doe);
if (OldState.DeviceState != State.DeviceState) {
change = TRUE;
if (OldState.DeviceState == PowerDeviceD0) {
notificationmask = PO_NOTIFY_TRANSITIONING_FROM_D0;
} else if (State.DeviceState == PowerDeviceD0) {
notificationmask = PO_NOTIFY_D0;
}
}
break;
default:
OldState.SystemState = PowerSystemUnspecified; // Never executed but keeps compiler happy
break;
}
if (! change) {
PopUnlockIrpSerialList(OldIrql2);
return OldState;
}
//
// We know what is going to happen. Always store the changed
// state first, so we can drop the lock and do the notification.
//
switch (Type) {
case SystemPowerState:
PopSetDoSystemPowerState(doe, State.SystemState);
break;
case DevicePowerState:
PopSetDoDevicePowerState(doe, State.DeviceState);
break;
}
PopUnlockIrpSerialList(OldIrql2);
//
// If anything to notify...
//
if (notificationmask && dope) {
PopStateChangeNotify(DeviceObject, notificationmask);
}
return OldState;
}
DEVICE_POWER_STATE
PopLockGetDoDevicePowerState(
IN PDEVOBJ_EXTENSION Doe
)
/*++
Routine Description:
Function which returns the power state of the specified device.
Unlike PopGetDoDevicePowerState, this routine also acquires and
releases the appropriate spinlock.
Arguments:
Doe - Supplies the devobj_extension of the device.
Return Value:
DEVICE_POWER_STATE
--*/
{
KIRQL OldIrql;
DEVICE_POWER_STATE State;
PopLockIrpSerialList(&OldIrql);
State = PopGetDoDevicePowerState(Doe);
PopUnlockIrpSerialList(OldIrql);
return(State);
}