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75 lines
2.8 KiB
C
75 lines
2.8 KiB
C
/** @file
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Metronome Architectural Protocol as defined in PI SPEC VOLUME 2 DXE
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This code abstracts the DXE core to provide delay services.
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Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#ifndef __ARCH_PROTOCOL_METRONOME_H__
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#define __ARCH_PROTOCOL_METRONOME_H__
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///
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/// Global ID for the Metronome Architectural Protocol
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///
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#define EFI_METRONOME_ARCH_PROTOCOL_GUID \
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{ 0x26baccb2, 0x6f42, 0x11d4, {0xbc, 0xe7, 0x0, 0x80, 0xc7, 0x3c, 0x88, 0x81 } }
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///
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/// Declare forward reference for the Metronome Architectural Protocol
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///
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typedef struct _EFI_METRONOME_ARCH_PROTOCOL EFI_METRONOME_ARCH_PROTOCOL;
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/**
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The WaitForTick() function waits for the number of ticks specified by
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TickNumber from a known time source in the platform. If TickNumber of
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ticks are detected, then EFI_SUCCESS is returned. The actual time passed
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between entry of this function and the first tick is between 0 and
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TickPeriod 100 nS units. If you want to guarantee that at least TickPeriod
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time has elapsed, wait for two ticks. This function waits for a hardware
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event to determine when a tick occurs. It is possible for interrupt
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processing, or exception processing to interrupt the execution of the
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WaitForTick() function. Depending on the hardware source for the ticks, it
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is possible for a tick to be missed. This function cannot guarantee that
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ticks will not be missed. If a timeout occurs waiting for the specified
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number of ticks, then EFI_TIMEOUT is returned.
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@param This The EFI_METRONOME_ARCH_PROTOCOL instance.
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@param TickNumber Number of ticks to wait.
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@retval EFI_SUCCESS The wait for the number of ticks specified by TickNumber
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succeeded.
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@retval EFI_TIMEOUT A timeout occurred waiting for the specified number of ticks.
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**/
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typedef
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EFI_STATUS
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(EFIAPI *EFI_METRONOME_WAIT_FOR_TICK)(
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IN EFI_METRONOME_ARCH_PROTOCOL *This,
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IN UINT32 TickNumber
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);
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///
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/// This protocol provides access to a known time source in the platform to the
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/// core. The core uses this known time source to produce core services that
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/// require calibrated delays.
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///
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struct _EFI_METRONOME_ARCH_PROTOCOL {
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EFI_METRONOME_WAIT_FOR_TICK WaitForTick;
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///
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/// The period of platform's known time source in 100 nS units.
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/// This value on any platform must be at least 10 uS, and must not
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/// exceed 200 uS. The value in this field is a constant that must
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/// not be modified after the Metronome architectural protocol is
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/// installed. All consumers must treat this as a read-only field.
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///
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UINT32 TickPeriod;
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};
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extern EFI_GUID gEfiMetronomeArchProtocolGuid;
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#endif
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