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