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 #ifndef _LOW_POWER_IDLE_TABLE_H_
  16 #define _LOW_POWER_IDLE_TABLE_H_
  17
  18 #include <IndustryStandard/Acpi.h>
  19
  20 #pragma pack(1)
  21
  22 ///
  23 /// LPI Structure Types
  24 ///
  25 #define ACPI_LPI_STRUCTURE_TYPE_NATIVE_CSTATE     0x00
  26
  27 ///
  28 /// Low Power Idle (LPI) State Flags
  29 ///
  30 typedef union {
  31   struct {
  32     UINT32 Disabled           : 1;  ///< If set, LPI state is not used
  33     /**
  34       If set, Residency counter is not available for this LPI state and
  35       Residency Counter Frequency is invalid
  36     **/
  37     UINT32 CounterUnavailable : 1;
  38     UINT32 Reserved           : 30; ///< Reserved for future use. Must be zero
  39   } Bits;
  40   UINT32 Data32;
  41 } ACPI_LPI_STATE_FLAGS;
  42
  43 ///
  44 /// Low Power Idle (LPI) structure with Native C-state instruction entry trigger descriptor
  45 ///
  46 typedef struct {
  47   UINT32                                  Type;   ///< LPI State descriptor Type 0
  48   UINT32                                  Length; ///< Length of LPI state Descriptor Structure
  49   ///
  50   /// Unique LPI state identifier: zero based, monotonically increasing identifier
  51   ///
  52   UINT16                                  UniqueId;
  53   UINT8                                   Reserved[2];  ///< Must be Zero
  54   ACPI_LPI_STATE_FLAGS                    Flags;        ///< LPI state flags
  55   /**
  56     The LPI entry trigger, matching an existing _CST.Register object, represented as a
  57     Generic Address Structure. All processors must request this state or deeper to trigger.
  58   **/
  59   EFI_ACPI_6_1_GENERIC_ADDRESS_STRUCTURE  EntryTrigger;
  60   UINT32                                  Residency;  ///< Minimum residency or break-even in uSec
  61   UINT32                                  Latency;    ///< Worst case exit latency in uSec
  62   /**
  63     [optional] Residency counter, represented as a Generic Address Structure.
  64     If not present, Flags[1] bit should be set.
  65   **/
  66   EFI_ACPI_6_1_GENERIC_ADDRESS_STRUCTURE  ResidencyCounter;
  67   /**
  68     [optional] Residency counter frequency in cycles per second. Value 0 indicates that
  69     counter runs at TSC frequency. Valid only if Residency Counter is present.
  70   **/
  71   UINT64                                  ResidencyCounterFrequency;
  72 } ACPI_LPI_NATIVE_CSTATE_DESCRIPTOR;
  73
  74 #pragma pack()
  75
  76 #endif