2 ACPI Low Power Idle Table (LPIT) definitions
4 Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
5 SPDX-License-Identifier: BSD-2-Clause-Patent
7 @par Revision Reference:
8 - ACPI Low Power Idle Table (LPIT) Revision 001, dated July 2014
9 http://www.uefi.org/sites/default/files/resources/ACPI_Low_Power_Idle_Table.pdf
12 - GAS - Generic Address Structure
13 - LPI - Low Power Idle
16 #ifndef _LOW_POWER_IDLE_TABLE_H_
17 #define _LOW_POWER_IDLE_TABLE_H_
19 #include <IndustryStandard/Acpi.h>
24 /// LPI Structure Types
26 #define ACPI_LPI_STRUCTURE_TYPE_NATIVE_CSTATE 0x00
29 /// Low Power Idle (LPI) State Flags
33 UINT32 Disabled
: 1; ///< If set, LPI state is not used
36 If set, Residency counter is not available for this LPI state and
37 Residency Counter Frequency is invalid
39 UINT32 CounterUnavailable
: 1;
40 UINT32 Reserved
: 30; ///< Reserved for future use. Must be zero
43 } ACPI_LPI_STATE_FLAGS
;
46 /// Low Power Idle (LPI) structure with Native C-state instruction entry trigger descriptor
49 UINT32 Type
; ///< LPI State descriptor Type 0
50 UINT32 Length
; ///< Length of LPI state Descriptor Structure
52 /// Unique LPI state identifier: zero based, monotonically increasing identifier
55 UINT8 Reserved
[2]; ///< Must be Zero
56 ACPI_LPI_STATE_FLAGS Flags
; ///< LPI state flags
59 The LPI entry trigger, matching an existing _CST.Register object, represented as a
60 Generic Address Structure. All processors must request this state or deeper to trigger.
62 EFI_ACPI_6_1_GENERIC_ADDRESS_STRUCTURE EntryTrigger
;
63 UINT32 Residency
; ///< Minimum residency or break-even in uSec
64 UINT32 Latency
; ///< Worst case exit latency in uSec
67 [optional] Residency counter, represented as a Generic Address Structure.
68 If not present, Flags[1] bit should be set.
70 EFI_ACPI_6_1_GENERIC_ADDRESS_STRUCTURE ResidencyCounter
;
73 [optional] Residency counter frequency in cycles per second. Value 0 indicates that
74 counter runs at TSC frequency. Valid only if Residency Counter is present.
76 UINT64 ResidencyCounterFrequency
;
77 } ACPI_LPI_NATIVE_CSTATE_DESCRIPTOR
;