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   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
   9
  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.
  12
  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
  16
  17   @par Glossary:
  18     - GAS - Generic Address Structure
  19     - LPI - Low Power Idle
  20 **/
  21 #ifndef _LOW_POWER_IDLE_TABLE_H_
  22 #define _LOW_POWER_IDLE_TABLE_H_
  23
  24 #include <IndustryStandard/Acpi.h>
  25
  26 #pragma pack(1)
  27
  28 ///
  29 /// LPI Structure Types
  30 ///
  31 #define ACPI_LPI_STRUCTURE_TYPE_NATIVE_CSTATE     0x00
  32
  33 ///
  34 /// Low Power Idle (LPI) State Flags
  35 ///
  36 typedef union {
  37   struct {
  38     UINT32 Disabled           : 1;  ///< If set, LPI state is not used
  39     /**
  40       If set, Residency counter is not available for this LPI state and
  41       Residency Counter Frequency is invalid
  42     **/
  43     UINT32 CounterUnavailable : 1;
  44     UINT32 Reserved           : 30; ///< Reserved for future use. Must be zero
  45   } Bits;
  46   UINT32 Data32;
  47 } ACPI_LPI_STATE_FLAGS;
  48
  49 ///
  50 /// Low Power Idle (LPI) structure with Native C-state instruction entry trigger descriptor
  51 ///
  52 typedef struct {
  53   UINT32                                  Type;   ///< LPI State descriptor Type 0
  54   UINT32                                  Length; ///< Length of LPI state Descriptor Structure
  55   ///
  56   /// Unique LPI state identifier: zero based, monotonically increasing identifier
  57   ///
  58   UINT16                                  UniqueId;
  59   UINT8                                   Reserved[2];  ///< Must be Zero
  60   ACPI_LPI_STATE_FLAGS                    Flags;        ///< LPI state flags
  61   /**
  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.
  64   **/
  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
  68   /**
  69     [optional] Residency counter, represented as a Generic Address Structure.
  70     If not present, Flags[1] bit should be set.
  71   **/
  72   EFI_ACPI_6_1_GENERIC_ADDRESS_STRUCTURE  ResidencyCounter;
  73   /**
  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.
  76   **/
  77   UINT64                                  ResidencyCounterFrequency;
  78 } ACPI_LPI_NATIVE_CSTATE_DESCRIPTOR;
  79
  80 #pragma pack()
  81
  82 #endif