EdkCompatibilityPkg/Foundation/Library/RuntimeDxe/EfiRuntimeLib/Ia32/Lock.c

   1 /*++
   2
   3 Copyright (c) 2004, Intel Corporation. All rights reserved.<BR>
   4 This program and the accompanying materials
   5 are licensed and made available under the terms and conditions of the BSD License
   6 which accompanies this distribution.  The full text of the license may be found at
   7 http://opensource.org/licenses/bsd-license.php
   8
   9 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  10 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  11
  12 Module Name:
  13
  14   Lock.c
  15
  16 Abstract:
  17
  18   Support for locking lib services.
  19
  20 --*/
  21
  22 #include "Tiano.h"
  23 #include "EfiDriverLib.h"
  24
  25 extern
  26 BOOLEAN
  27 EfiAtRuntime (
  28   VOID
  29   );
  30
  31 VOID
  32 EfiInitializeLock (
  33   IN OUT EFI_LOCK *Lock,
  34   IN EFI_TPL      Priority
  35   )
  36 /*++
  37
  38 Routine Description:
  39
  40   Initialize a basic mutual exclusion lock.   Each lock
  41   provides mutual exclusion access at it's task priority
  42   level.  Since there is no-premption (at any TPL) or
  43   multiprocessor support, acquiring the lock only consists
  44   of raising to the locks TPL.
  45
  46   Note on a check build ASSERT()s are used to ensure proper
  47   lock usage.
  48
  49 Arguments:
  50
  51   Lock        - The EFI_LOCK structure to initialize
  52
  53   Priority    - The task priority level of the lock
  54
  55
  56 Returns:
  57
  58   An initialized Efi Lock structure.
  59
  60 --*/
  61 {
  62   Lock->Tpl       = Priority;
  63   Lock->OwnerTpl  = 0;
  64   Lock->Lock      = 0;
  65 }
  66
  67 EFI_STATUS
  68 EfiAcquireLockOrFail (
  69   IN EFI_LOCK  *Lock
  70   )
  71 /*++
  72
  73 Routine Description:
  74
  75   Initialize a basic mutual exclusion lock.   Each lock
  76   provides mutual exclusion access at it's task priority
  77   level.  Since there is no-premption (at any TPL) or
  78   multiprocessor support, acquiring the lock only consists
  79   of raising to the locks TPL.
  80
  81 Arguments:
  82
  83   Lock        - The EFI_LOCK structure to initialize
  84
  85 Returns:
  86
  87   EFI_SUCCESS       - Lock Owned.
  88   EFI_ACCESS_DENIED - Reentrant Lock Acquisition, Lock not Owned.
  89
  90 --*/
  91 {
  92   if (Lock->Lock != 0) {
  93     //
  94     // Lock is already owned, so bail out
  95     //
  96     return EFI_ACCESS_DENIED;
  97   }
  98
  99   if (!EfiAtRuntime ()) {
 100     //
 101     // The check is just debug code for core inplementation. It must
 102     //  always be true in a driver
 103     //
 104     Lock->OwnerTpl = gBS->RaiseTPL (Lock->Tpl);
 105   }
 106
 107   Lock->Lock += 1;
 108   return EFI_SUCCESS;
 109 }
 110
 111 VOID
 112 EfiAcquireLock (
 113   IN EFI_LOCK  *Lock
 114   )
 115 /*++
 116
 117 Routine Description:
 118
 119   Raising to the task priority level of the mutual exclusion
 120   lock, and then acquires ownership of the lock.
 121
 122 Arguments:
 123
 124   Lock - The lock to acquire
 125
 126 Returns:
 127
 128   Lock owned
 129
 130 --*/
 131 {
 132   EFI_STATUS  Status;
 133
 134   Status = EfiAcquireLockOrFail (Lock);
 135
 136   //
 137   // Lock was already locked.
 138   //
 139   ASSERT_EFI_ERROR (Status);
 140 }
 141
 142 VOID
 143 EfiReleaseLock (
 144   IN EFI_LOCK  *Lock
 145   )
 146 /*++
 147
 148 Routine Description:
 149
 150     Releases ownership of the mutual exclusion lock, and
 151     restores the previous task priority level.
 152
 153 Arguments:
 154
 155     Lock - The lock to release
 156
 157 Returns:
 158
 159     Lock unowned
 160
 161 --*/
 162 {
 163   EFI_TPL Tpl;
 164
 165   Tpl = Lock->OwnerTpl;
 166
 167   ASSERT (Lock->Lock == 1);
 168   Lock->Lock -= 1;
 169
 170   if (!EfiAtRuntime ()) {
 171     //
 172     // The check is just debug code for core inplementation. It must
 173     //  always be true in a driver
 174     //
 175     gBS->RestoreTPL (Tpl);
 176   }
 177 }