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 VOID 26 EfiInitializeLock ( 27 IN OUT EFI_LOCK *Lock, 28 IN EFI_TPL Priority 29 ) 30 /*++ 31 32 Routine Description: 33 34 Initialize a basic mutual exclusion lock. Each lock 35 provides mutual exclusion access at it's task priority 36 level. Since there is no-premption (at any TPL) or 37 multiprocessor support, acquiring the lock only consists 38 of raising to the locks TPL. 39 40 Note on a check build ASSERT()s are used to ensure proper 41 lock usage. 42 43 Arguments: 44 45 Lock - The EFI_LOCK structure to initialize 46 47 Priority - The task priority level of the lock 48 49 50 Returns: 51 52 An initialized Efi Lock structure. 53 54 --*/ 55 { 56 Lock->Tpl = Priority; 57 Lock->OwnerTpl = 0; 58 Lock->Lock = 0; 59 } 60 61 EFI_STATUS 62 EfiAcquireLockOrFail ( 63 IN EFI_LOCK *Lock 64 ) 65 /*++ 66 67 Routine Description: 68 69 Initialize a basic mutual exclusion lock. Each lock 70 provides mutual exclusion access at it's task priority 71 level. Since there is no-premption (at any TPL) or 72 multiprocessor support, acquiring the lock only consists 73 of raising to the locks TPL. 74 75 Arguments: 76 77 Lock - The EFI_LOCK structure to initialize 78 79 Returns: 80 81 EFI_SUCCESS - Lock Owned. 82 EFI_ACCESS_DENIED - Reentrant Lock Acquisition, Lock not Owned. 83 84 --*/ 85 { 86 if (Lock->Lock != 0) { 87 // 88 // Lock is already owned, so bail out 89 // 90 return EFI_ACCESS_DENIED; 91 } 92 93 Lock->OwnerTpl = gBS->RaiseTPL (Lock->Tpl); 94 95 Lock->Lock += 1; 96 return EFI_SUCCESS; 97 } 98 99 VOID 100 EfiAcquireLock ( 101 IN EFI_LOCK *Lock 102 ) 103 /*++ 104 105 Routine Description: 106 107 Raising to the task priority level of the mutual exclusion 108 lock, and then acquires ownership of the lock. 109 110 Arguments: 111 112 Lock - The lock to acquire 113 114 Returns: 115 116 Lock owned 117 118 --*/ 119 { 120 EFI_STATUS Status; 121 122 Status = EfiAcquireLockOrFail (Lock); 123 124 // 125 // Lock was already locked. 126 // 127 ASSERT_EFI_ERROR (Status); 128 } 129 130 VOID 131 EfiReleaseLock ( 132 IN EFI_LOCK *Lock 133 ) 134 /*++ 135 136 Routine Description: 137 138 Releases ownership of the mutual exclusion lock, and 139 restores the previous task priority level. 140 141 Arguments: 142 143 Lock - The lock to release 144 145 Returns: 146 147 Lock unowned 148 149 --*/ 150 { 151 EFI_TPL Tpl; 152 153 Tpl = Lock->OwnerTpl; 154 155 ASSERT (Lock->Lock == 1); 156 Lock->Lock -= 1; 157 158 gBS->RestoreTPL (Tpl); 159 } 160
