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 - 2018, Intel Corporation. All rights reserved.<BR> 7 SPDX-License-Identifier: BSD-2-Clause-Patent 8 9 **/ 10 11 #ifndef __ARCH_PROTOCOL_METRONOME_H__ 12 #define __ARCH_PROTOCOL_METRONOME_H__ 13 14 /// 15 /// Global ID for the Metronome Architectural Protocol 16 /// 17 #define EFI_METRONOME_ARCH_PROTOCOL_GUID \ 18 { 0x26baccb2, 0x6f42, 0x11d4, {0xbc, 0xe7, 0x0, 0x80, 0xc7, 0x3c, 0x88, 0x81 } } 19 20 /// 21 /// Declare forward reference for the Metronome Architectural Protocol 22 /// 23 typedef struct _EFI_METRONOME_ARCH_PROTOCOL EFI_METRONOME_ARCH_PROTOCOL; 24 25 /** 26 The WaitForTick() function waits for the number of ticks specified by 27 TickNumber from a known time source in the platform. If TickNumber of 28 ticks are detected, then EFI_SUCCESS is returned. The actual time passed 29 between entry of this function and the first tick is between 0 and 30 TickPeriod 100 nS units. If you want to guarantee that at least TickPeriod 31 time has elapsed, wait for two ticks. This function waits for a hardware 32 event to determine when a tick occurs. It is possible for interrupt 33 processing, or exception processing to interrupt the execution of the 34 WaitForTick() function. Depending on the hardware source for the ticks, it 35 is possible for a tick to be missed. This function cannot guarantee that 36 ticks will not be missed. If a timeout occurs waiting for the specified 37 number of ticks, then EFI_TIMEOUT is returned. 38 39 @param This The EFI_METRONOME_ARCH_PROTOCOL instance. 40 @param TickNumber Number of ticks to wait. 41 42 @retval EFI_SUCCESS The wait for the number of ticks specified by TickNumber 43 succeeded. 44 @retval EFI_TIMEOUT A timeout occurred waiting for the specified number of ticks. 45 46 **/ 47 typedef 48 EFI_STATUS 49 (EFIAPI *EFI_METRONOME_WAIT_FOR_TICK)( 50 IN EFI_METRONOME_ARCH_PROTOCOL *This, 51 IN UINT32 TickNumber 52 ); 53 54 /// 55 /// This protocol provides access to a known time source in the platform to the 56 /// core. The core uses this known time source to produce core services that 57 /// require calibrated delays. 58 /// 59 struct _EFI_METRONOME_ARCH_PROTOCOL { 60 EFI_METRONOME_WAIT_FOR_TICK WaitForTick; 61 62 /// 63 /// The period of platform's known time source in 100 nS units. 64 /// This value on any platform must be at least 10 uS, and must not 65 /// exceed 200 uS. The value in this field is a constant that must 66 /// not be modified after the Metronome architectural protocol is 67 /// installed. All consumers must treat this as a read-only field. 68 /// 69 UINT32 TickPeriod; 70 }; 71 72 extern EFI_GUID gEfiMetronomeArchProtocolGuid; 73 74 #endif 75