MdeModulePkg/Core/Dxe/Event/Tpl.c

   1 /** @file
   2   Task priority (TPL) functions.
   3
   4 Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
   5 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 #include "Event.h"
  17
  18 /**
  19   Set Interrupt State.
  20
  21   @param  Enable  The state of enable or disable interrupt
  22
  23 **/
  24 VOID
  25 CoreSetInterruptState (
  26   IN BOOLEAN      Enable
  27   )
  28 {
  29   EFI_STATUS  Status;
  30   BOOLEAN     InSmm;
  31
  32   if (gCpu == NULL) {
  33     return;
  34   }
  35   if (!Enable) {
  36     gCpu->DisableInterrupt (gCpu);
  37     return;
  38   }
  39   if (gSmmBase2 == NULL) {
  40     gCpu->EnableInterrupt (gCpu);
  41     return;
  42   }
  43   Status = gSmmBase2->InSmm (gSmmBase2, &InSmm);
  44   if (!EFI_ERROR (Status) && !InSmm) {
  45     gCpu->EnableInterrupt(gCpu);
  46   }
  47 }
  48
  49
  50 /**
  51   Raise the task priority level to the new level.
  52   High level is implemented by disabling processor interrupts.
  53
  54   @param  NewTpl  New task priority level
  55
  56   @return The previous task priority level
  57
  58 **/
  59 EFI_TPL
  60 EFIAPI
  61 CoreRaiseTpl (
  62   IN EFI_TPL      NewTpl
  63   )
  64 {
  65   EFI_TPL     OldTpl;
  66
  67   OldTpl = gEfiCurrentTpl;
  68   ASSERT (OldTpl <= NewTpl);
  69   ASSERT (VALID_TPL (NewTpl));
  70
  71   //
  72   // If raising to high level, disable interrupts
  73   //
  74   if (NewTpl >= TPL_HIGH_LEVEL  &&  OldTpl < TPL_HIGH_LEVEL) {
  75     CoreSetInterruptState (FALSE);
  76   }
  77
  78   //
  79   // Set the new value
  80   //
  81   gEfiCurrentTpl = NewTpl;
  82
  83   return OldTpl;
  84 }
  85
  86
  87
  88
  89 /**
  90   Lowers the task priority to the previous value.   If the new
  91   priority unmasks events at a higher priority, they are dispatched.
  92
  93   @param  NewTpl  New, lower, task priority
  94
  95 **/
  96 VOID
  97 EFIAPI
  98 CoreRestoreTpl (
  99   IN EFI_TPL NewTpl
 100   )
 101 {
 102   EFI_TPL     OldTpl;
 103
 104   OldTpl = gEfiCurrentTpl;
 105   ASSERT (NewTpl <= OldTpl);
 106   ASSERT (VALID_TPL (NewTpl));
 107
 108   //
 109   // If lowering below HIGH_LEVEL, make sure
 110   // interrupts are enabled
 111   //
 112
 113   if (OldTpl >= TPL_HIGH_LEVEL  &&  NewTpl < TPL_HIGH_LEVEL) {
 114     gEfiCurrentTpl = TPL_HIGH_LEVEL;
 115   }
 116
 117   //
 118   // Dispatch any pending events
 119   //
 120   while (((-2 << NewTpl) & gEventPending) != 0) {
 121     gEfiCurrentTpl = HighBitSet64 (gEventPending);
 122     if (gEfiCurrentTpl < TPL_HIGH_LEVEL) {
 123       CoreSetInterruptState (TRUE);
 124     }
 125     CoreDispatchEventNotifies (gEfiCurrentTpl);
 126   }
 127
 128   //
 129   // Set the new value
 130   //
 131
 132   gEfiCurrentTpl = NewTpl;
 133
 134   //
 135   // If lowering below HIGH_LEVEL, make sure
 136   // interrupts are enabled
 137   //
 138   if (gEfiCurrentTpl < TPL_HIGH_LEVEL) {
 139     CoreSetInterruptState (TRUE);
 140   }
 141
 142 }