| 1 | /** @file
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| 2 | Metronome Architectural Protocol as defined in PI SPEC VOLUME 2 DXE
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| 3 |
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| 4 | This code abstracts the DXE core to provide delay services.
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| 5 |
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| 6 | Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
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| 7 | SPDX-License-Identifier: BSD-2-Clause-Patent
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| 8 |
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| 9 | **/
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| 10 |
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| 11 | #ifndef __ARCH_PROTOCOL_METRONOME_H__
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| 12 | #define __ARCH_PROTOCOL_METRONOME_H__
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| 13 |
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| 14 | ///
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| 15 | /// Global ID for the Metronome Architectural Protocol
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| 16 | ///
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| 17 | #define EFI_METRONOME_ARCH_PROTOCOL_GUID \
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| 18 | { 0x26baccb2, 0x6f42, 0x11d4, {0xbc, 0xe7, 0x0, 0x80, 0xc7, 0x3c, 0x88, 0x81 } }
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| 19 |
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| 20 | ///
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| 21 | /// Declare forward reference for the Metronome Architectural Protocol
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| 22 | ///
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| 23 | typedef struct _EFI_METRONOME_ARCH_PROTOCOL EFI_METRONOME_ARCH_PROTOCOL;
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| 24 |
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| 25 | /**
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| 26 | The WaitForTick() function waits for the number of ticks specified by
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| 27 | TickNumber from a known time source in the platform. If TickNumber of
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| 28 | ticks are detected, then EFI_SUCCESS is returned. The actual time passed
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| 29 | between entry of this function and the first tick is between 0 and
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| 30 | TickPeriod 100 nS units. If you want to guarantee that at least TickPeriod
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| 31 | time has elapsed, wait for two ticks. This function waits for a hardware
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| 32 | event to determine when a tick occurs. It is possible for interrupt
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| 33 | processing, or exception processing to interrupt the execution of the
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| 34 | WaitForTick() function. Depending on the hardware source for the ticks, it
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| 35 | is possible for a tick to be missed. This function cannot guarantee that
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| 36 | ticks will not be missed. If a timeout occurs waiting for the specified
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| 37 | number of ticks, then EFI_TIMEOUT is returned.
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| 38 |
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| 39 | @param This The EFI_METRONOME_ARCH_PROTOCOL instance.
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| 40 | @param TickNumber Number of ticks to wait.
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| 41 |
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| 42 | @retval EFI_SUCCESS The wait for the number of ticks specified by TickNumber
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| 43 | succeeded.
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| 44 | @retval EFI_TIMEOUT A timeout occurred waiting for the specified number of ticks.
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| 45 |
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| 46 | **/
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| 47 | typedef
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| 48 | EFI_STATUS
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| 49 | (EFIAPI *EFI_METRONOME_WAIT_FOR_TICK)(
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| 50 | IN EFI_METRONOME_ARCH_PROTOCOL *This,
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| 51 | IN UINT32 TickNumber
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| 52 | );
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| 53 |
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| 54 | ///
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| 55 | /// This protocol provides access to a known time source in the platform to the
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| 56 | /// core. The core uses this known time source to produce core services that
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| 57 | /// require calibrated delays.
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| 58 | ///
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| 59 | struct _EFI_METRONOME_ARCH_PROTOCOL {
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| 60 | EFI_METRONOME_WAIT_FOR_TICK WaitForTick;
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| 61 |
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| 62 | ///
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| 63 | /// The period of platform's known time source in 100 nS units.
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| 64 | /// This value on any platform must be at least 10 uS, and must not
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| 65 | /// exceed 200 uS. The value in this field is a constant that must
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| 66 | /// not be modified after the Metronome architectural protocol is
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| 67 | /// installed. All consumers must treat this as a read-only field.
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| 68 | ///
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| 69 | UINT32 TickPeriod;
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| 70 | };
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| 71 |
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| 72 | extern EFI_GUID gEfiMetronomeArchProtocolGuid;
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| 73 |
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| 74 | #endif
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