MdePkg/Include/IndustryStandard/LowPowerIdleTable.h

   1 /** @file
   2   ACPI Low Power Idle Table (LPIT) definitions
   3
   4   Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   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
  10
  11   @par Glossary:
  12     - GAS - Generic Address Structure
  13     - LPI - Low Power Idle
  14 **/
  15
  16 #ifndef _LOW_POWER_IDLE_TABLE_H_
  17 #define _LOW_POWER_IDLE_TABLE_H_
  18
  19 #include <IndustryStandard/Acpi.h>
  20
  21 #pragma pack(1)
  22
  23 ///
  24 /// LPI Structure Types
  25 ///
  26 #define ACPI_LPI_STRUCTURE_TYPE_NATIVE_CSTATE  0x00
  27
  28 ///
  29 /// Low Power Idle (LPI) State Flags
  30 ///
  31 typedef union {
  32   struct {
  33     UINT32    Disabled           : 1; ///< If set, LPI state is not used
  34
  35     /**
  36       If set, Residency counter is not available for this LPI state and
  37       Residency Counter Frequency is invalid
  38     **/
  39     UINT32    CounterUnavailable : 1;
  40     UINT32    Reserved           : 30; ///< Reserved for future use. Must be zero
  41   } Bits;
  42   UINT32    Data32;
  43 } ACPI_LPI_STATE_FLAGS;
  44
  45 ///
  46 /// Low Power Idle (LPI) structure with Native C-state instruction entry trigger descriptor
  47 ///
  48 typedef struct {
  49   UINT32                                    Type;   ///< LPI State descriptor Type 0
  50   UINT32                                    Length; ///< Length of LPI state Descriptor Structure
  51   ///
  52   /// Unique LPI state identifier: zero based, monotonically increasing identifier
  53   ///
  54   UINT16                                    UniqueId;
  55   UINT8                                     Reserved[2]; ///< Must be Zero
  56   ACPI_LPI_STATE_FLAGS                      Flags;       ///< LPI state flags
  57
  58   /**
  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.
  61   **/
  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
  65
  66   /**
  67     [optional] Residency counter, represented as a Generic Address Structure.
  68     If not present, Flags[1] bit should be set.
  69   **/
  70   EFI_ACPI_6_1_GENERIC_ADDRESS_STRUCTURE    ResidencyCounter;
  71
  72   /**
  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.
  75   **/
  76   UINT64                                    ResidencyCounterFrequency;
  77 } ACPI_LPI_NATIVE_CSTATE_DESCRIPTOR;
  78
  79 #pragma pack()
  80
  81 #endif