MdePkg: Add ACPI Low Power Idle Table (LPIT) definitions

ACPI Low Power Idle Table (LPIT) Revision 001, dated July 2014
http://www.uefi.org/sites/default/files/resources/ACPI_Low_Power_Idle_Table.pdf

Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Giri P Mudusuru <giri.p.mudusuru@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>

MdePkg/Include/IndustryStandard/LowPowerIdleTable.h

@@ -0,0 +1,82 @@
+/** @file
+  ACPI Low Power Idle Table (LPIT) definitions
+
+  Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
+  This program and the accompanying materials
+  are licensed and made available under the terms and conditions of the BSD License
+  which accompanies this distribution.  The full text of the license may be found at
+  http://opensource.org/licenses/bsd-license.php
+
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+  @par Revision Reference:
+    - ACPI Low Power Idle Table (LPIT) Revision 001, dated July 2014
+      http://www.uefi.org/sites/default/files/resources/ACPI_Low_Power_Idle_Table.pdf
+
+  @par Glossary:
+    - GAS - Generic Address Structure
+    - LPI - Low Power Idle
+**/
+#ifndef _LOW_POWER_IDLE_TABLE_H_
+#define _LOW_POWER_IDLE_TABLE_H_
+
+#include <IndustryStandard/Acpi.h>
+
+#pragma pack(1)
+
+///
+/// LPI Structure Types
+///
+#define ACPI_LPI_STRUCTURE_TYPE_NATIVE_CSTATE     0x00
+
+///
+/// Low Power Idle (LPI) State Flags
+///
+typedef union {
+  struct {
+    UINT32 Disabled           : 1;  ///< If set, LPI state is not used
+    /**
+      If set, Residency counter is not available for this LPI state and
+      Residency Counter Frequency is invalid
+    **/
+    UINT32 CounterUnavailable : 1;
+    UINT32 Reserved           : 30; ///< Reserved for future use. Must be zero
+  } Bits;
+  UINT32 Data32;
+} ACPI_LPI_STATE_FLAGS;
+
+///
+/// Low Power Idle (LPI) structure with Native C-state instruction entry trigger descriptor
+///
+typedef struct {
+  UINT32                                  Type;   ///< LPI State descriptor Type 0
+  UINT32                                  Length; ///< Length of LPI state Descriptor Structure
+  ///
+  /// Unique LPI state identifier: zero based, monotonically increasing identifier
+  ///
+  UINT16                                  UniqueId;
+  UINT8                                   Reserved[2];  ///< Must be Zero
+  ACPI_LPI_STATE_FLAGS                    Flags;        ///< LPI state flags
+  /**
+    The LPI entry trigger, matching an existing _CST.Register object, represented as a
+    Generic Address Structure. All processors must request this state or deeper to trigger.
+  **/
+  EFI_ACPI_6_1_GENERIC_ADDRESS_STRUCTURE  EntryTrigger;
+  UINT32                                  Residency;  ///< Minimum residency or break-even in uSec
+  UINT32                                  Latency;    ///< Worst case exit latency in uSec
+  /**
+    [optional] Residency counter, represented as a Generic Address Structure.
+    If not present, Flags[1] bit should be set.
+  **/
+  EFI_ACPI_6_1_GENERIC_ADDRESS_STRUCTURE  ResidencyCounter;
+  /**
+    [optional] Residency counter frequency in cycles per second. Value 0 indicates that
+    counter runs at TSC frequency. Valid only if Residency Counter is present.
+  **/
+  UINT64                                  ResidencyCounterFrequency;
+} ACPI_LPI_NATIVE_CSTATE_DESCRIPTOR;
+
+#pragma pack()
+
+#endif