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/*++
Copyright (c) 2005, Intel Corporation
All rights reserved. This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
Module Name:
Lock.c
Abstract:
Support for locking lib services.
--*/
#include "Tiano.h"
#include "EfiDriverLib.h"
extern
BOOLEAN
EfiAtRuntime (
VOID
);
VOID
EfiInitializeLock (
IN OUT EFI_LOCK *Lock,
IN EFI_TPL Priority
)
/*++
Routine Description:
Initialize a basic mutual exclusion lock. Each lock
provides mutual exclusion access at it's task priority
level. Since there is no-premption (at any TPL) or
multiprocessor support, acquiring the lock only consists
of raising to the locks TPL.
Note on a check build ASSERT()s are used to ensure proper
lock usage.
Arguments:
Lock - The EFI_LOCK structure to initialize
Priority - The task priority level of the lock
Returns:
An initialized Efi Lock structure.
--*/
{
Lock->Tpl = Priority;
Lock->OwnerTpl = 0;
Lock->Lock = 0;
}
EFI_STATUS
EfiAcquireLockOrFail (
IN EFI_LOCK *Lock
)
/*++
Routine Description:
Initialize a basic mutual exclusion lock. Each lock
provides mutual exclusion access at it's task priority
level. Since there is no-premption (at any TPL) or
multiprocessor support, acquiring the lock only consists
of raising to the locks TPL.
Arguments:
Lock - The EFI_LOCK structure to initialize
Returns:
EFI_SUCCESS - Lock Owned.
EFI_ACCESS_DENIED - Reentrant Lock Acquisition, Lock not Owned.
--*/
{
if (Lock->Lock != 0) {
//
// Lock is already owned, so bail out
//
return EFI_ACCESS_DENIED;
}
if (!EfiAtRuntime ()) {
//
// The check is just debug code for core inplementation. It must
// always be true in a driver
//
Lock->OwnerTpl = gBS->RaiseTPL (Lock->Tpl);
}
Lock->Lock += 1;
return EFI_SUCCESS;
}
VOID
EfiAcquireLock (
IN EFI_LOCK *Lock
)
/*++
Routine Description:
Raising to the task priority level of the mutual exclusion
lock, and then acquires ownership of the lock.
Arguments:
Lock - The lock to acquire
Returns:
Lock owned
--*/
{
EFI_STATUS Status;
Status = EfiAcquireLockOrFail (Lock);
//
// Lock was already locked.
//
ASSERT_EFI_ERROR (Status);
}
VOID
EfiReleaseLock (
IN EFI_LOCK *Lock
)
/*++
Routine Description:
Releases ownership of the mutual exclusion lock, and
restores the previous task priority level.
Arguments:
Lock - The lock to release
Returns:
Lock unowned
--*/
{
EFI_TPL Tpl;
Tpl = Lock->OwnerTpl;
ASSERT (Lock->Lock == 1);
Lock->Lock -= 1;
if (!EfiAtRuntime ()) {
//
// The check is just debug code for core inplementation. It must
// always be true in a driver
//
gBS->RestoreTPL (Tpl);
}
}
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