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 110