MdeModulePkg/Core/Dxe/Event/Tpl.c

   1 /** @file
   2   Task priority (TPL) functions.
   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 #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   if (gCpu != NULL) {
  30     if (Enable) {
  31       gCpu->EnableInterrupt(gCpu);
  32     } else {
  33       gCpu->DisableInterrupt(gCpu);
  34     }
  35   }
  36 }
  37
  38
  39 /**
  40   Raise the task priority level to the new level.
  41   High level is implemented by disabling processor interrupts.
  42
  43   @param  NewTpl  New task priority level
  44
  45   @return The previous task priority level
  46
  47 **/
  48 EFI_TPL
  49 EFIAPI
  50 CoreRaiseTpl (
  51   IN EFI_TPL      NewTpl
  52   )
  53 {
  54   EFI_TPL     OldTpl;
  55
  56   OldTpl = gEfiCurrentTpl;
  57   ASSERT (OldTpl <= NewTpl);
  58   ASSERT (VALID_TPL (NewTpl));
  59
  60   //
  61   // If raising to high level, disable interrupts
  62   //
  63   if (NewTpl >= TPL_HIGH_LEVEL  &&  OldTpl < TPL_HIGH_LEVEL) {
  64     CoreSetInterruptState (FALSE);
  65   }
  66
  67   //
  68   // Set the new value
  69   //
  70   gEfiCurrentTpl = NewTpl;
  71
  72   return OldTpl;
  73 }
  74
  75
  76
  77
  78 /**
  79   Lowers the task priority to the previous value.   If the new
  80   priority unmasks events at a higher priority, they are dispatched.
  81
  82   @param  NewTpl  New, lower, task priority
  83
  84 **/
  85 VOID
  86 EFIAPI
  87 CoreRestoreTpl (
  88   IN EFI_TPL NewTpl
  89   )
  90 {
  91   EFI_TPL     OldTpl;
  92
  93   OldTpl = gEfiCurrentTpl;
  94   ASSERT (NewTpl <= OldTpl);
  95   ASSERT (VALID_TPL (NewTpl));
  96
  97   //
  98   // If lowering below HIGH_LEVEL, make sure
  99   // interrupts are enabled
 100   //
 101
 102   if (OldTpl >= TPL_HIGH_LEVEL  &&  NewTpl < TPL_HIGH_LEVEL) {
 103     gEfiCurrentTpl = TPL_HIGH_LEVEL;
 104   }
 105
 106   //
 107   // Dispatch any pending events
 108   //
 109   while (((-2 << NewTpl) & gEventPending) != 0) {
 110     gEfiCurrentTpl = HighBitSet64 (gEventPending);
 111     if (gEfiCurrentTpl < TPL_HIGH_LEVEL) {
 112       CoreSetInterruptState (TRUE);
 113     }
 114     CoreDispatchEventNotifies (gEfiCurrentTpl);
 115   }
 116
 117   //
 118   // Set the new value
 119   //
 120
 121   gEfiCurrentTpl = NewTpl;
 122
 123   //
 124   // If lowering below HIGH_LEVEL, make sure
 125   // interrupts are enabled
 126   //
 127   if (gEfiCurrentTpl < TPL_HIGH_LEVEL) {
 128     CoreSetInterruptState (TRUE);
 129   }
 130
 131 }