1 /*++ 2 3 Copyright (c) 2005, 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 } 178
