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. These primitives may be implemented 19 as Esal calls but since these result in small code that us position 20 independent, we can use lib functions. ESAL calls have a significant 21 software overhead and too deep nesting is bad for the stack. 22 23 --*/ 24 25 #include "Tiano.h" 26 #include "EfiDriverLib.h" 27 28 extern 29 BOOLEAN 30 EfiAtRuntime ( 31 VOID 32 ); 33 34 VOID 35 EfiInitializeLock ( 36 IN OUT EFI_LOCK *Lock, 37 IN EFI_TPL Priority 38 ) 39 /*++ 40 41 Routine Description: 42 43 Initialize a basic mutual exclusion lock. There is 44 no concept of TPL at runtime hence priority is 45 ignored. 46 47 Arguments: 48 49 Lock - The EFI_LOCK structure to initialize 50 51 Priority - Ignored 52 53 54 Returns: 55 56 An initialized Efi Lock structure. 57 58 --*/ 59 { 60 Lock->Tpl = Priority; 61 Lock->OwnerTpl = 0; 62 Lock->Lock = 0; 63 } 64 65 EFI_STATUS 66 EfiAcquireLockOrFail ( 67 IN EFI_LOCK *Lock 68 ) 69 /*++ 70 71 Routine Description: 72 73 Initialize a basic mutual exclusion lock. For now, 74 only allow one level of nesting. 75 76 Arguments: 77 78 Lock - The EFI_LOCK structure to initialize 79 80 Returns: 81 82 EFI_SUCCESS - Lock Owned. 83 EFI_ACCESS_DENIED - Reentrant Lock Acquisition, Lock not Owned. 84 85 --*/ 86 { 87 if (Lock->Lock != 0) { 88 // 89 // Lock is already owned, so bail out 90 // 91 return EFI_ACCESS_DENIED; 92 } 93 94 if (!EfiAtRuntime ()) { 95 // 96 // The check is just debug code for core inplementation. It must 97 // always be true in a driver 98 // 99 Lock->OwnerTpl = gBS->RaiseTPL (Lock->Tpl); 100 } 101 102 Lock->Lock += 1; 103 return EFI_SUCCESS; 104 } 105 106 VOID 107 EfiAcquireLock ( 108 IN EFI_LOCK *Lock 109 ) 110 /*++ 111 112 Routine Description: 113 114 Acquires ownership of the lock. 115 116 Arguments: 117 118 Lock - The lock to acquire 119 120 Returns: 121 122 Lock owned 123 124 --*/ 125 { 126 EFI_STATUS Status; 127 128 Status = EfiAcquireLockOrFail (Lock); 129 130 // 131 // Lock was already locked. 132 // 133 ASSERT_EFI_ERROR (Status); 134 } 135 136 VOID 137 EfiReleaseLock ( 138 IN EFI_LOCK *Lock 139 ) 140 /*++ 141 142 Routine Description: 143 144 Releases ownership of the mutual exclusion lock. 145 146 Arguments: 147 148 Lock - The lock to release 149 150 Returns: 151 152 Lock unowned 153 154 --*/ 155 { 156 EFI_TPL Tpl; 157 158 Tpl = Lock->OwnerTpl; 159 160 ASSERT (Lock->Lock == 1); 161 Lock->Lock -= 1; 162 163 if (!EfiAtRuntime ()) { 164 // 165 // The check is just debug code for core inplementation. It must 166 // always be true in a driver 167 // 168 gBS->RestoreTPL (Tpl); 169 } 170 } 171
