MdeModulePkg/Core/Dxe/Library/Library.c

   1 /** @file
   2   DXE Core library services.
   3
   4 Copyright (c) 2006 - 2008, Intel Corporation. <BR>
   5 All rights reserved. This program and the accompanying materials
   6 are licensed and made available under the terms and conditions of the BSD License
   7 which accompanies this distribution.  The full text of the license may be found at
   8 http://opensource.org/licenses/bsd-license.php
   9
  10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13 **/
  14
  15 #include "DxeMain.h"
  16
  17 //
  18 // Lock Stuff
  19 //
  20 /**
  21   Initialize a basic mutual exclusion lock.   Each lock
  22   provides mutual exclusion access at it's task priority
  23   level.  Since there is no-premption (at any TPL) or
  24   multiprocessor support, acquiring the lock only consists
  25   of raising to the locks TPL.
  26
  27   @param  Lock               The EFI_LOCK structure to initialize
  28
  29   @retval EFI_SUCCESS        Lock Owned.
  30   @retval EFI_ACCESS_DENIED  Reentrant Lock Acquisition, Lock not Owned.
  31
  32 **/
  33 EFI_STATUS
  34 CoreAcquireLockOrFail (
  35   IN EFI_LOCK  *Lock
  36   )
  37 {
  38   ASSERT (Lock != NULL);
  39   ASSERT (Lock->Lock != EfiLockUninitialized);
  40
  41   if (Lock->Lock == EfiLockAcquired) {
  42     //
  43     // Lock is already owned, so bail out
  44     //
  45     return EFI_ACCESS_DENIED;
  46   }
  47
  48   Lock->OwnerTpl = CoreRaiseTpl (Lock->Tpl);
  49
  50   Lock->Lock = EfiLockAcquired;
  51   return EFI_SUCCESS;
  52 }
  53
  54
  55
  56 /**
  57   Raising to the task priority level of the mutual exclusion
  58   lock, and then acquires ownership of the lock.
  59
  60   @param  Lock               The lock to acquire
  61
  62   @return Lock owned
  63
  64 **/
  65 VOID
  66 CoreAcquireLock (
  67   IN EFI_LOCK  *Lock
  68   )
  69 {
  70   ASSERT (Lock != NULL);
  71   ASSERT (Lock->Lock == EfiLockReleased);
  72
  73   Lock->OwnerTpl = CoreRaiseTpl (Lock->Tpl);
  74   Lock->Lock     = EfiLockAcquired;
  75 }
  76
  77
  78
  79 /**
  80   Releases ownership of the mutual exclusion lock, and
  81   restores the previous task priority level.
  82
  83   @param  Lock               The lock to release
  84
  85   @return Lock unowned
  86
  87 **/
  88 VOID
  89 CoreReleaseLock (
  90   IN EFI_LOCK  *Lock
  91   )
  92 {
  93   EFI_TPL Tpl;
  94
  95   ASSERT (Lock != NULL);
  96   ASSERT (Lock->Lock == EfiLockAcquired);
  97
  98   Tpl = Lock->OwnerTpl;
  99
 100   Lock->Lock = EfiLockReleased;
 101
 102   CoreRestoreTpl (Tpl);
 103 }
 104
 105
 106 /**
 107   Create a protocol notification event and return it.
 108
 109   @param  ProtocolGuid       Protocol to register notification event on.
 110   @param  NotifyTpl          Maximum TPL to signal the NotifyFunction.
 111   @param  NotifyFunction     EFI notification routine.
 112   @param  NotifyContext      Context passed into Event when it is created.
 113   @param  Registration       Registration key returned from
 114                              RegisterProtocolNotify().
 115   @param  SignalFlag         Boolean value to decide whether kick the event after
 116                              register or not.
 117
 118   @return The EFI_EVENT that has been registered to be signaled when a ProtocolGuid
 119           is added to the system.
 120
 121 **/
 122 EFI_EVENT
 123 CoreCreateProtocolNotifyEvent (
 124   IN EFI_GUID             *ProtocolGuid,
 125   IN EFI_TPL              NotifyTpl,
 126   IN EFI_EVENT_NOTIFY     NotifyFunction,
 127   IN VOID                 *NotifyContext,
 128   OUT VOID                **Registration,
 129   IN  BOOLEAN             SignalFlag
 130   )
 131 {
 132   EFI_STATUS              Status;
 133   EFI_EVENT               Event;
 134
 135   //
 136   // Create the event
 137   //
 138   Status = CoreCreateEvent (
 139             EVT_NOTIFY_SIGNAL,
 140             NotifyTpl,
 141             NotifyFunction,
 142             NotifyContext,
 143             &Event
 144             );
 145   ASSERT_EFI_ERROR (Status);
 146
 147   //
 148   // Register for protocol notifactions on this event
 149   //
 150   Status = CoreRegisterProtocolNotify (
 151              ProtocolGuid,
 152              Event,
 153              Registration
 154              );
 155   ASSERT_EFI_ERROR (Status);
 156
 157   if (SignalFlag) {
 158     //
 159     // Kick the event so we will perform an initial pass of
 160     // current installed drivers
 161     //
 162     CoreSignalEvent (Event);
 163   }
 164
 165   return Event;
 166 }
 167
 168