2 ACPI Low Power Idle Table (LPIT) definitions
4 Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
5 This program and the accompanying materials
6 are licensed and made available under the terms and conditions of the BSD License
7 which accompanies this distribution. The full text of the license may be found at
8 http://opensource.org/licenses/bsd-license.php
10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
13 @par Revision Reference:
14 - ACPI Low Power Idle Table (LPIT) Revision 001, dated July 2014
15 http://www.uefi.org/sites/default/files/resources/ACPI_Low_Power_Idle_Table.pdf
18 - GAS - Generic Address Structure
19 - LPI - Low Power Idle
21 #ifndef _LOW_POWER_IDLE_TABLE_H_
22 #define _LOW_POWER_IDLE_TABLE_H_
24 #include <IndustryStandard/Acpi.h>
29 /// LPI Structure Types
31 #define ACPI_LPI_STRUCTURE_TYPE_NATIVE_CSTATE 0x00
34 /// Low Power Idle (LPI) State Flags
38 UINT32 Disabled
: 1; ///< If set, LPI state is not used
40 If set, Residency counter is not available for this LPI state and
41 Residency Counter Frequency is invalid
43 UINT32 CounterUnavailable
: 1;
44 UINT32 Reserved
: 30; ///< Reserved for future use. Must be zero
47 } ACPI_LPI_STATE_FLAGS
;
50 /// Low Power Idle (LPI) structure with Native C-state instruction entry trigger descriptor
53 UINT32 Type
; ///< LPI State descriptor Type 0
54 UINT32 Length
; ///< Length of LPI state Descriptor Structure
56 /// Unique LPI state identifier: zero based, monotonically increasing identifier
59 UINT8 Reserved
[2]; ///< Must be Zero
60 ACPI_LPI_STATE_FLAGS Flags
; ///< LPI state flags
62 The LPI entry trigger, matching an existing _CST.Register object, represented as a
63 Generic Address Structure. All processors must request this state or deeper to trigger.
65 EFI_ACPI_6_1_GENERIC_ADDRESS_STRUCTURE EntryTrigger
;
66 UINT32 Residency
; ///< Minimum residency or break-even in uSec
67 UINT32 Latency
; ///< Worst case exit latency in uSec
69 [optional] Residency counter, represented as a Generic Address Structure.
70 If not present, Flags[1] bit should be set.
72 EFI_ACPI_6_1_GENERIC_ADDRESS_STRUCTURE ResidencyCounter
;
74 [optional] Residency counter frequency in cycles per second. Value 0 indicates that
75 counter runs at TSC frequency. Valid only if Residency Counter is present.
77 UINT64 ResidencyCounterFrequency
;
78 } ACPI_LPI_NATIVE_CSTATE_DESCRIPTOR
;