mirror of https://github.com/acidanthera/audk.git
102 lines
3.7 KiB
C
102 lines
3.7 KiB
C
/** @file
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EFI Timestamp Protocol as defined in UEFI2.4 Specification.
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Used to provide a platform independent interface for retrieving a high resolution timestamp counter.
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Copyright (c) 2013, Intel Corporation. All rights reserved.<BR>
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This program and the accompanying materials
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are licensed and made available under the terms and conditions of the BSD License
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which accompanies this distribution. The full text of the license may be found at
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http://opensource.org/licenses/bsd-license.php
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THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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@par Revision Reference:
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This Protocol is introduced in UEFI Specification 2.4
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**/
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#ifndef __EFI_TIME_STAMP_PROTOCOL_H__
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#define __EFI_TIME_STAMP_PROTOCOL_H__
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#define EFI_TIMESTAMP_PROTOCOL_GUID \
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{ 0xafbfde41, 0x2e6e, 0x4262, {0xba, 0x65, 0x62, 0xb9, 0x23, 0x6e, 0x54, 0x95 } }
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///
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/// Declare forward reference for the Time Stamp Protocol
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///
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typedef struct _EFI_TIMESTAMP_PROTOCOL EFI_TIMESTAMP_PROTOCOL;
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///
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/// EFI_TIMESTAMP_PROPERTIES
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///
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typedef struct {
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///
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/// The frequency of the timestamp counter in Hz.
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///
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UINT64 Frequency;
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///
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/// The value that the timestamp counter ends with immediately before it rolls over.
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/// For example, a 64-bit free running counter would have an EndValue of 0xFFFFFFFFFFFFFFFF.
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/// A 24-bit free running counter would have an EndValue of 0xFFFFFF.
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///
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UINT64 EndValue;
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} EFI_TIMESTAMP_PROPERTIES;
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/**
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Retrieves the current value of a 64-bit free running timestamp counter.
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The counter shall count up in proportion to the amount of time that has passed. The counter value
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will always roll over to zero. The properties of the counter can be retrieved from GetProperties().
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The caller should be prepared for the function to return the same value twice across successive calls.
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The counter value will not go backwards other than when wrapping, as defined by EndValue in GetProperties().
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The frequency of the returned timestamp counter value must remain constant. Power management operations that
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affect clocking must not change the returned counter frequency. The quantization of counter value updates may
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vary as long as the value reflecting time passed remains consistent.
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@param None.
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@retval The current value of the free running timestamp counter.
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**/
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typedef
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UINT64
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(EFIAPI *TIMESTAMP_GET)(
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VOID
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);
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/**
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Obtains timestamp counter properties including frequency and value limits.
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@param[out] Properties The properties of the timestamp counter.
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@retval EFI_SUCCESS The properties were successfully retrieved.
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@retval EFI_DEVICE_ERROR An error occurred trying to retrieve the properties of the timestamp
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counter subsystem. Properties is not pedated.
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@retval EFI_INVALID_PARAMETER Properties is NULL.
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**/
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typedef
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EFI_STATUS
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(EFIAPI *TIMESTAMP_GET_PROPERTIES)(
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OUT EFI_TIMESTAMP_PROPERTIES *Properties
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);
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///
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/// EFI_TIMESTAMP_PROTOCOL
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/// The protocol provides a platform independent interface for retrieving a high resolution
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/// timestamp counter.
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///
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struct _EFI_TIMESTAMP_PROTOCOL {
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TIMESTAMP_GET GetTimestamp;
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TIMESTAMP_GET_PROPERTIES GetProperties;
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};
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extern EFI_GUID gEfiTimestampProtocolGuid;
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#endif
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