EdkCompatibilityPkg/Foundation/Core/Dxe/ArchProtocol/Metronome/Metronome.h

   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   Metronome.h
  15
  16 Abstract:
  17
  18   Metronome Architectural Protocol as defined in DXE CIS
  19
  20   This code abstracts the DXE core to provide delay services.
  21
  22 --*/
  23
  24 #ifndef _ARCH_PROTOCOL_METRONOME_H_
  25 #define _ARCH_PROTOCOL_METRONOME_H_
  26
  27 //
  28 // Global ID for the Metronome Architectural Protocol
  29 //
  30 #define EFI_METRONOME_ARCH_PROTOCOL_GUID \
  31   { 0x26baccb2, 0x6f42, 0x11d4, {0xbc, 0xe7, 0x0, 0x80, 0xc7, 0x3c, 0x88, 0x81} }
  32
  33 //
  34 // Declare forward reference for the Metronome Architectural Protocol
  35 //
  36 EFI_FORWARD_DECLARATION (EFI_METRONOME_ARCH_PROTOCOL);
  37
  38 typedef
  39 EFI_STATUS
  40 (EFIAPI *EFI_METRONOME_WAIT_FOR_TICK) (
  41    IN EFI_METRONOME_ARCH_PROTOCOL   *This,
  42    IN UINT32                        TickNumber
  43   );
  44 /*++
  45
  46 Routine Description:
  47
  48   The WaitForTick() function waits for the number of ticks specified by
  49   TickNumber from a known time source in the platform.  If TickNumber of
  50   ticks are detected, then EFI_SUCCESS is returned.  The actual time passed
  51   between entry of this function and the first tick is between 0 and
  52   TickPeriod 100 nS units.  If you want to guarantee that at least TickPeriod
  53   time has elapsed, wait for two ticks.  This function waits for a hardware
  54   event to determine when a tick occurs.  It is possible for interrupt
  55   processing, or exception processing to interrupt the execution of the
  56   WaitForTick() function.  Depending on the hardware source for the ticks, it
  57   is possible for a tick to be missed.  This function cannot guarantee that
  58   ticks will not be missed.  If a timeout occurs waiting for the specified
  59   number of ticks, then EFI_TIMEOUT is returned.
  60
  61 Arguments:
  62
  63   This       - The EFI_METRONOME_ARCH_PROTOCOL instance.
  64
  65   TickNumber - Number of ticks to wait.
  66
  67 Returns:
  68
  69   EFI_SUCCESS - The wait for the number of ticks specified by TickNumber
  70                 succeeded.
  71
  72   EFI_TIMEOUT - A timeout occurred waiting for the specified number of ticks.
  73
  74 --*/
  75
  76 //
  77 // Interface stucture for the Metronome Architectural Protocol
  78 //
  79 struct _EFI_METRONOME_ARCH_PROTOCOL {
  80   EFI_METRONOME_WAIT_FOR_TICK  WaitForTick;
  81   UINT32                       TickPeriod;
  82 };
  83
  84 /*++
  85
  86   Protocol Description:
  87     This protocol provides access to a known time source in the platform to the
  88     core.  The core uses this known time source to produce core services that
  89     require calibrated delays.
  90
  91   Parameters:
  92
  93     WaitForTick - Waits for a specified number of ticks from a known time source
  94                   in the platform.  The actual time passed between entry of this
  95                   function and the first tick is between 0 and TickPeriod 100 nS
  96                   units.  If you want to guarantee that at least TickPeriod time
  97                   has elapsed, wait for two ticks.
  98
  99     TickPeriod  - The period of platform's known time source in 100 nS units.
 100                   This value on any platform must be at least 10 uS, and must not
 101                   exceed 200 uS.  The value in this field is a constant that must
 102                   not be modified after the Metronome architectural protocol is
 103                   installed.  All consumers must treat this as a read-only field.
 104
 105 --*/
 106
 107 extern EFI_GUID gEfiMetronomeArchProtocolGuid;
 108
 109 #endif