1 /** @file 2 Metronome Architectural Protocol as defined in PI SPEC VOLUME 2 DXE 3 4 This code abstracts the DXE core to provide delay services. 5 6 Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR> 7 This program and the accompanying materials 8 are licensed and made available under the terms and conditions of the BSD License 9 which accompanies this distribution. The full text of the license may be found at 10 http://opensource.org/licenses/bsd-license.php 11 12 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 13 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. 14 15 **/ 16 17 #ifndef __ARCH_PROTOCOL_METRONOME_H__ 18 #define __ARCH_PROTOCOL_METRONOME_H__ 19 20 /// 21 /// Global ID for the Metronome Architectural Protocol 22 /// 23 #define EFI_METRONOME_ARCH_PROTOCOL_GUID \ 24 { 0x26baccb2, 0x6f42, 0x11d4, {0xbc, 0xe7, 0x0, 0x80, 0xc7, 0x3c, 0x88, 0x81 } } 25 26 /// 27 /// Declare forward reference for the Metronome Architectural Protocol 28 /// 29 typedef struct _EFI_METRONOME_ARCH_PROTOCOL EFI_METRONOME_ARCH_PROTOCOL; 30 31 /** 32 The WaitForTick() function waits for the number of ticks specified by 33 TickNumber from a known time source in the platform. If TickNumber of 34 ticks are detected, then EFI_SUCCESS is returned. The actual time passed 35 between entry of this function and the first tick is between 0 and 36 TickPeriod 100 nS units. If you want to guarantee that at least TickPeriod 37 time has elapsed, wait for two ticks. This function waits for a hardware 38 event to determine when a tick occurs. It is possible for interrupt 39 processing, or exception processing to interrupt the execution of the 40 WaitForTick() function. Depending on the hardware source for the ticks, it 41 is possible for a tick to be missed. This function cannot guarantee that 42 ticks will not be missed. If a timeout occurs waiting for the specified 43 number of ticks, then EFI_TIMEOUT is returned. 44 45 @param This The EFI_METRONOME_ARCH_PROTOCOL instance. 46 @param TickNumber Number of ticks to wait. 47 48 @retval EFI_SUCCESS The wait for the number of ticks specified by TickNumber 49 succeeded. 50 @retval EFI_TIMEOUT A timeout occurred waiting for the specified number of ticks. 51 52 **/ 53 typedef 54 EFI_STATUS 55 (EFIAPI *EFI_METRONOME_WAIT_FOR_TICK)( 56 IN EFI_METRONOME_ARCH_PROTOCOL *This, 57 IN UINT32 TickNumber 58 ); 59 60 /// 61 /// This protocol provides access to a known time source in the platform to the 62 /// core. The core uses this known time source to produce core services that 63 /// require calibrated delays. 64 /// 65 struct _EFI_METRONOME_ARCH_PROTOCOL { 66 EFI_METRONOME_WAIT_FOR_TICK WaitForTick; 67 68 /// 69 /// The period of platform's known time source in 100 nS units. 70 /// This value on any platform must be at least 10 uS, and must not 71 /// exceed 200 uS. The value in this field is a constant that must 72 /// not be modified after the Metronome architectural protocol is 73 /// installed. All consumers must treat this as a read-only field. 74 /// 75 UINT32 TickPeriod; 76 }; 77 78 extern EFI_GUID gEfiMetronomeArchProtocolGuid; 79 80 #endif 81