/** @file
  SSDT Cpu Topology Table Generator.

  Copyright (c) 2021, Arm Limited. All rights reserved.<BR>
  SPDX-License-Identifier: BSD-2-Clause-Patent

  @par Reference(s):
    - ACPI 6.3 Specification - January 2019 - s8.4 Declaring Processors
**/

#include <Library/AcpiLib.h>
#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/DebugLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Protocol/AcpiTable.h>

// Module specific include files.
#include <AcpiTableGenerator.h>
#include <ConfigurationManagerObject.h>
#include <ConfigurationManagerHelper.h>
#include <Library/AcpiHelperLib.h>
#include <Library/TableHelperLib.h>
#include <Library/AmlLib/AmlLib.h>
#include <Protocol/ConfigurationManagerProtocol.h>

#include "SsdtCpuTopologyGenerator.h"

/** ARM standard SSDT Cpu Topology Table Generator.

Requirements:
  The following Configuration Manager Object(s) are required by
  this Generator:
  - EArmObjGicCInfo
  - EArmObjProcHierarchyInfo (OPTIONAL) along with
  - EArmObjCmRef (OPTIONAL)
  - EArmObjLpiInfo (OPTIONAL)
*/

/** This macro expands to a function that retrieves the GIC
    CPU interface Information from the Configuration Manager.
*/
GET_OBJECT_LIST (
  EObjNameSpaceArm,
  EArmObjGicCInfo,
  CM_ARM_GICC_INFO
  );

/**
  This macro expands to a function that retrieves the Processor Hierarchy
  information from the Configuration Manager.
*/
GET_OBJECT_LIST (
  EObjNameSpaceArm,
  EArmObjProcHierarchyInfo,
  CM_ARM_PROC_HIERARCHY_INFO
  );

/**
  This macro expands to a function that retrieves the cross-CM-object-
  reference information from the Configuration Manager.
*/
GET_OBJECT_LIST (
  EObjNameSpaceArm,
  EArmObjCmRef,
  CM_ARM_OBJ_REF
  );

/**
  This macro expands to a function that retrieves the Lpi
  information from the Configuration Manager.
*/
GET_OBJECT_LIST (
  EObjNameSpaceArm,
  EArmObjLpiInfo,
  CM_ARM_LPI_INFO
  );

/** Initialize the TokenTable.

  One entry should be allocated for each CM_ARM_PROC_HIERARCHY_INFO
  structure of the platform. The TokenTable allows to have a mapping:
  Index <-> CM_OBJECT_TOKEN (to CM_ARM_LPI_INFO structures).

  There will always be less sets of Lpi states (CM_ARM_OBJ_REF)
  than the number of cpus/clusters (CM_ARM_PROC_HIERARCHY_INFO).

  @param [in]  Generator  The SSDT Cpu Topology generator.
  @param [in]  Count      Number of entries to allocate in the TokenTable.

  @retval EFI_SUCCESS            Success.
  @retval EFI_INVALID_PARAMETER  Invalid parameter.
  @retval EFI_OUT_OF_RESOURCES   Failed to allocate memory.
**/
STATIC
EFI_STATUS
EFIAPI
TokenTableInitialize (
  IN  ACPI_CPU_TOPOLOGY_GENERATOR  *Generator,
  IN  UINT32                       Count
  )
{
  CM_OBJECT_TOKEN  *Table;

  if ((Generator == NULL) ||
      (Count == 0)        ||
      (Count >= MAX_NODE_COUNT))
  {
    ASSERT (0);
    return EFI_INVALID_PARAMETER;
  }

  Table = AllocateZeroPool (sizeof (CM_OBJECT_TOKEN) * Count);
  if (Table == NULL) {
    ASSERT (0);
    return EFI_OUT_OF_RESOURCES;
  }

  Generator->TokenTable.Table = Table;

  return EFI_SUCCESS;
}

/** Free the TokenTable.

  @param [in]  Generator    The SSDT Cpu Topology generator.
**/
STATIC
VOID
EFIAPI
TokenTableFree (
  IN  ACPI_CPU_TOPOLOGY_GENERATOR  *Generator
  )
{
  ASSERT (Generator != NULL);
  ASSERT (Generator->TokenTable.Table != NULL);

  if (Generator->TokenTable.Table != NULL) {
    FreePool (Generator->TokenTable.Table);
  }
}

/** Add a new entry to the TokenTable and return its index.

  If an entry with Token is already available in the table,
  return its index without adding a new entry.

  @param [in]  Generator  The SSDT Cpu Topology generator.
  @param [in]  Token      New Token entry to add.

  @retval The index of the token entry in the TokenTable.
**/
STATIC
UINT32
EFIAPI
TokenTableAdd (
  IN  ACPI_CPU_TOPOLOGY_GENERATOR  *Generator,
  IN  CM_OBJECT_TOKEN              Token
  )
{
  CM_OBJECT_TOKEN  *Table;
  UINT32           Index;
  UINT32           LastIndex;

  ASSERT (Generator != NULL);
  ASSERT (Generator->TokenTable.Table != NULL);

  Table     = Generator->TokenTable.Table;
  LastIndex = Generator->TokenTable.LastIndex;

  // Search if there is already an entry with this Token.
  for (Index = 0; Index < LastIndex; Index++) {
    if (Table[Index] == Token) {
      return Index;
    }
  }

  ASSERT (LastIndex < MAX_NODE_COUNT);
  ASSERT (LastIndex < Generator->ProcNodeCount);

  // If no, create a new entry.
  Table[LastIndex] = Token;

  return Generator->TokenTable.LastIndex++;
}

/** Write a string 'Xxxx\0' in AslName (5 bytes long),
  with 'X' being the leading char of the name, and
  with 'xxx' being Value in hexadecimal.

  As 'xxx' in hexadecimal represents a number on 12 bits,
  we have Value < (1 << 12).

  @param [in]       LeadChar  Leading char of the name.
  @param [in]       Value     Hex value of the name.
                              Must be lower than (2 << 12).
  @param [in, out]  AslName   Pointer to write the 'Xxxx' string to.
                              Must be at least 5 bytes long.

  @retval EFI_SUCCESS               Success.
  @retval EFI_INVALID_PARAMETER     Invalid parameter.
**/
STATIC
EFI_STATUS
EFIAPI
WriteAslName (
  IN      CHAR8   LeadChar,
  IN      UINT32  Value,
  IN OUT  CHAR8   *AslName
  )
{
  UINT8  Index;

  if ((Value >= MAX_NODE_COUNT)  ||
      (AslName == NULL))
  {
    ASSERT (0);
    return EFI_INVALID_PARAMETER;
  }

  AslName[0]                 = LeadChar;
  AslName[AML_NAME_SEG_SIZE] = '\0';

  for (Index = 0; Index < AML_NAME_SEG_SIZE - 1; Index++) {
    AslName[AML_NAME_SEG_SIZE - Index - 1] =
      AsciiFromHex (((Value >> (4 * Index)) & 0xF));
  }

  return EFI_SUCCESS;
}

/** Create and add an _LPI method to Cpu/Cluster Node.

  For instance, transform an AML node from:
  Device (C002)
  {
      Name (_UID, 2)
      Name (_HID, "ACPI0007")
  }

  To:
  Device (C002)
  {
      Name (_UID, 2)
      Name (_HID, "ACPI0007")
      Method (_LPI, 0, NotSerialized)
      {
          Return (\_SB.L003)
      }
  }

  @param [in]  Generator              The SSDT Cpu Topology generator.
  @param [in]  ProcHierarchyNodeInfo  CM_ARM_PROC_HIERARCHY_INFO describing
                                      the Cpu.
  @param [in]  Node                   Node to which the _LPI method is
                                      attached. Can represent a Cpu or a
                                      Cluster.

  @retval EFI_SUCCESS             The function completed successfully.
  @retval EFI_INVALID_PARAMETER   Invalid parameter.
  @retval EFI_OUT_OF_RESOURCES    Failed to allocate memory.
**/
STATIC
EFI_STATUS
EFIAPI
CreateAmlLpiMethod (
  IN  ACPI_CPU_TOPOLOGY_GENERATOR  *Generator,
  IN  CM_ARM_PROC_HIERARCHY_INFO   *ProcHierarchyNodeInfo,
  IN  AML_OBJECT_NODE_HANDLE       *Node
  )
{
  EFI_STATUS  Status;
  UINT32      TokenIndex;
  CHAR8       AslName[SB_SCOPE_PREFIX_SIZE + AML_NAME_SEG_SIZE];

  ASSERT (Generator != NULL);
  ASSERT (ProcHierarchyNodeInfo != NULL);
  ASSERT (ProcHierarchyNodeInfo->LpiToken != CM_NULL_TOKEN);
  ASSERT (Node != NULL);

  TokenIndex = TokenTableAdd (Generator, ProcHierarchyNodeInfo->LpiToken);

  CopyMem (AslName, SB_SCOPE_PREFIX, SB_SCOPE_PREFIX_SIZE);

  Status = WriteAslName (
             'L',
             TokenIndex,
             AslName + SB_SCOPE_PREFIX_SIZE - 1
             );
  if (EFI_ERROR (Status)) {
    ASSERT (0);
    return Status;
  }

  // ASL:
  // Method (_LPI, 0) {
  //   Return ([AslName])
  // }
  Status = AmlCodeGenMethodRetNameString (
             "_LPI",
             AslName,
             0,
             FALSE,
             0,
             Node,
             NULL
             );
  if (EFI_ERROR (Status)) {
    ASSERT (0);
  }

  return Status;
}

/** Generate all the Lpi states under the '_SB' scope.

  This function generates the following ASL code:
  Scope (\_SB) {
    Name (L000, Package() {
      0, // Version
      0, // Level Index
      X, // Count
      Package() {
        [An Lpi state]
      },
      Package() {
        [Another Lpi state]
      },
    } // Name L000

    Name (L001, Package() {
      ...
    } // Name L001

    ...
  } // Scope /_SB

  The Lpi states are fetched from the Configuration Manager.
  The names of the Lpi states are generated from the TokenTable.

  @param [in]  Generator        The SSDT Cpu Topology generator.
  @param [in]  CfgMgrProtocol   Pointer to the Configuration Manager
                                Protocol Interface.
  @param [in] ScopeNode         Scope node handle ('\_SB' scope).

  @retval EFI_SUCCESS             Success.
  @retval EFI_INVALID_PARAMETER   Invalid parameter.
  @retval EFI_OUT_OF_RESOURCES    Failed to allocate memory.
**/
STATIC
EFI_STATUS
EFIAPI
GenerateLpiStates (
  IN        ACPI_CPU_TOPOLOGY_GENERATOR                   *Generator,
  IN  CONST EDKII_CONFIGURATION_MANAGER_PROTOCOL  *CONST  CfgMgrProtocol,
  IN        AML_OBJECT_NODE_HANDLE                        ScopeNode
  )
{
  EFI_STATUS  Status;

  UINT32  Index;
  UINT32  LastIndex;

  AML_OBJECT_NODE_HANDLE  LpiNode;
  CM_ARM_OBJ_REF          *LpiRefInfo;
  UINT32                  LpiRefInfoCount;
  UINT32                  LpiRefIndex;
  CM_ARM_LPI_INFO         *LpiInfo;
  CHAR8                   AslName[AML_NAME_SEG_SIZE + 1];

  ASSERT (Generator != NULL);
  ASSERT (Generator->TokenTable.Table != NULL);
  ASSERT (CfgMgrProtocol != NULL);
  ASSERT (ScopeNode != NULL);

  LastIndex = Generator->TokenTable.LastIndex;

  // For each entry in the TokenTable, create a name in the AML namespace
  // under SB_SCOPE, to store the Lpi states associated with the LpiToken.
  for (Index = 0; Index < LastIndex; Index++) {
    Status = WriteAslName ('L', Index, AslName);
    if (EFI_ERROR (Status)) {
      ASSERT (0);
      return Status;
    }

    // We do not support the LevelId field for now, let it to 0.
    Status = AmlCreateLpiNode (AslName, 1, 0, ScopeNode, &LpiNode);
    if (EFI_ERROR (Status)) {
      ASSERT (0);
      return Status;
    }

    // Fetch the LPI objects referenced by the token.
    Status = GetEArmObjCmRef (
               CfgMgrProtocol,
               Generator->TokenTable.Table[Index],
               &LpiRefInfo,
               &LpiRefInfoCount
               );
    if (EFI_ERROR (Status)) {
      ASSERT (0);
      return Status;
    }

    for (LpiRefIndex = 0; LpiRefIndex < LpiRefInfoCount; LpiRefIndex++) {
      // For each CM_ARM_LPI_INFO referenced by the token, add an Lpi state.
      Status = GetEArmObjLpiInfo (
                 CfgMgrProtocol,
                 LpiRefInfo[LpiRefIndex].ReferenceToken,
                 &LpiInfo,
                 NULL
                 );
      if (EFI_ERROR (Status)) {
        ASSERT (0);
        return Status;
      }

      Status = AmlAddLpiState (
                 LpiInfo->MinResidency,
                 LpiInfo->WorstCaseWakeLatency,
                 LpiInfo->Flags,
                 LpiInfo->ArchFlags,
                 LpiInfo->ResCntFreq,
                 LpiInfo->EnableParentState,
                 LpiInfo->IsInteger ?
                 NULL :
                 &LpiInfo->RegisterEntryMethod,
                 LpiInfo->IsInteger ?
                 LpiInfo->IntegerEntryMethod :
                 0,
                 &LpiInfo->ResidencyCounterRegister,
                 &LpiInfo->UsageCounterRegister,
                 LpiInfo->StateName,
                 LpiNode
                 );
      if (EFI_ERROR (Status)) {
        ASSERT (0);
        return Status;
      }
    } // for LpiRefIndex
  } // for Index

  return EFI_SUCCESS;
}

/** Create a Cpu in the AML namespace.

  This generates the following ASL code:
  Device (C002)
  {
      Name (_UID, 2)
      Name (_HID, "ACPI0007")
  }

  @param [in]  Generator    The SSDT Cpu Topology generator.
  @param [in]  ParentNode   Parent node to attach the Cpu node to.
  @param [in]  GicCInfo     CM_ARM_GICC_INFO object used to create the node.
  @param [in]  CpuIndex     Index used to generate the node name.
  @param [out] CpuNodePtr   If not NULL, return the created Cpu node.

  @retval EFI_SUCCESS             Success.
  @retval EFI_INVALID_PARAMETER   Invalid parameter.
  @retval EFI_OUT_OF_RESOURCES    Failed to allocate memory.
**/
STATIC
EFI_STATUS
EFIAPI
CreateAmlCpu (
  IN   ACPI_CPU_TOPOLOGY_GENERATOR  *Generator,
  IN   AML_NODE_HANDLE              ParentNode,
  IN   CM_ARM_GICC_INFO             *GicCInfo,
  IN   UINT32                       CpuIndex,
  OUT  AML_OBJECT_NODE_HANDLE       *CpuNodePtr OPTIONAL
  )
{
  EFI_STATUS              Status;
  AML_OBJECT_NODE_HANDLE  CpuNode;
  CHAR8                   AslName[AML_NAME_SEG_SIZE + 1];

  ASSERT (Generator != NULL);
  ASSERT (ParentNode != NULL);
  ASSERT (GicCInfo != NULL);

  Status = WriteAslName ('C', CpuIndex, AslName);
  if (EFI_ERROR (Status)) {
    ASSERT (0);
    return Status;
  }

  Status = AmlCodeGenDevice (AslName, ParentNode, &CpuNode);
  if (EFI_ERROR (Status)) {
    ASSERT (0);
    return Status;
  }

  Status = AmlCodeGenNameInteger (
             "_UID",
             GicCInfo->AcpiProcessorUid,
             CpuNode,
             NULL
             );
  if (EFI_ERROR (Status)) {
    ASSERT (0);
    return Status;
  }

  Status = AmlCodeGenNameString (
             "_HID",
             ACPI_HID_PROCESSOR_DEVICE,
             CpuNode,
             NULL
             );
  if (EFI_ERROR (Status)) {
    ASSERT (0);
    return Status;
  }

  // If requested, return the handle to the CpuNode.
  if (CpuNodePtr != NULL) {
    *CpuNodePtr = CpuNode;
  }

  return Status;
}

/** Create a Cpu in the AML namespace from a CM_ARM_PROC_HIERARCHY_INFO
    CM object.

  @param [in]  Generator              The SSDT Cpu Topology generator.
  @param [in]  CfgMgrProtocol         Pointer to the Configuration Manager
                                      Protocol Interface.
  @param [in]  ParentNode             Parent node to attach the Cpu node to.
  @param [in]  CpuIndex               Index used to generate the node name.
  @param [in]  ProcHierarchyNodeInfo  CM_ARM_PROC_HIERARCHY_INFO describing
                                      the Cpu.

  @retval EFI_SUCCESS             Success.
  @retval EFI_INVALID_PARAMETER   Invalid parameter.
  @retval EFI_OUT_OF_RESOURCES    Failed to allocate memory.
**/
STATIC
EFI_STATUS
EFIAPI
CreateAmlCpuFromProcHierarchy (
  IN        ACPI_CPU_TOPOLOGY_GENERATOR                   *Generator,
  IN  CONST EDKII_CONFIGURATION_MANAGER_PROTOCOL  *CONST  CfgMgrProtocol,
  IN        AML_NODE_HANDLE                               ParentNode,
  IN        UINT32                                        CpuIndex,
  IN        CM_ARM_PROC_HIERARCHY_INFO                    *ProcHierarchyNodeInfo
  )
{
  EFI_STATUS              Status;
  CM_ARM_GICC_INFO        *GicCInfo;
  AML_OBJECT_NODE_HANDLE  CpuNode;

  ASSERT (Generator != NULL);
  ASSERT (CfgMgrProtocol != NULL);
  ASSERT (ParentNode != NULL);
  ASSERT (ProcHierarchyNodeInfo != NULL);
  ASSERT (ProcHierarchyNodeInfo->GicCToken != CM_NULL_TOKEN);

  Status = GetEArmObjGicCInfo (
             CfgMgrProtocol,
             ProcHierarchyNodeInfo->GicCToken,
             &GicCInfo,
             NULL
             );
  if (EFI_ERROR (Status)) {
    ASSERT (0);
    return Status;
  }

  Status = CreateAmlCpu (Generator, ParentNode, GicCInfo, CpuIndex, &CpuNode);
  if (EFI_ERROR (Status)) {
    ASSERT (0);
    return Status;
  }

  // If a set of Lpi states is associated with the
  // CM_ARM_PROC_HIERARCHY_INFO, create an _LPI method returning them.
  if (ProcHierarchyNodeInfo->LpiToken != CM_NULL_TOKEN) {
    Status = CreateAmlLpiMethod (Generator, ProcHierarchyNodeInfo, CpuNode);
    ASSERT_EFI_ERROR (Status);
  }

  return Status;
}

/** Create a Cluster in the AML namespace.

  Any CM_ARM_PROC_HIERARCHY_INFO object with the following flags is
  assumed to be a cluster:
   - EFI_ACPI_6_3_PPTT_PACKAGE_NOT_PHYSICAL
   - EFI_ACPI_6_3_PPTT_PROCESSOR_ID_INVALID
   - EFI_ACPI_6_3_PPTT_NODE_IS_NOT_LEAF

  This generates the following ASL code:
  Device (C002)
  {
      Name (_UID, 2)
      Name (_HID, "ACPI0010")
  }

  @param [in]  Generator              The SSDT Cpu Topology generator.
  @param [in]  CfgMgrProtocol         Pointer to the Configuration Manager
                                      Protocol Interface.
  @param [in]  ParentNode             Parent node to attach the Cluster
                                      node to.
  @param [in]  ProcHierarchyNodeInfo  CM_ARM_PROC_HIERARCHY_INFO object used
                                      to create the node.
  @param [in]  ClusterIndex           Index used to generate the node name.
  @param [out] ClusterNodePtr         If success, contains the created Cluster
                                      node.

  @retval EFI_SUCCESS             Success.
  @retval EFI_INVALID_PARAMETER   Invalid parameter.
  @retval EFI_OUT_OF_RESOURCES    Failed to allocate memory.
**/
STATIC
EFI_STATUS
EFIAPI
CreateAmlCluster (
  IN        ACPI_CPU_TOPOLOGY_GENERATOR                   *Generator,
  IN  CONST EDKII_CONFIGURATION_MANAGER_PROTOCOL  *CONST  CfgMgrProtocol,
  IN        AML_NODE_HANDLE                               ParentNode,
  IN        CM_ARM_PROC_HIERARCHY_INFO                    *ProcHierarchyNodeInfo,
  IN        UINT32                                        ClusterIndex,
  OUT       AML_OBJECT_NODE_HANDLE                        *ClusterNodePtr
  )
{
  EFI_STATUS              Status;
  AML_OBJECT_NODE_HANDLE  ClusterNode;
  CHAR8                   AslNameCluster[AML_NAME_SEG_SIZE + 1];

  ASSERT (Generator != NULL);
  ASSERT (CfgMgrProtocol != NULL);
  ASSERT (ParentNode != NULL);
  ASSERT (ProcHierarchyNodeInfo != NULL);
  ASSERT (ClusterNodePtr != NULL);

  Status = WriteAslName ('C', ClusterIndex, AslNameCluster);
  if (EFI_ERROR (Status)) {
    ASSERT (0);
    return Status;
  }

  Status = AmlCodeGenDevice (AslNameCluster, ParentNode, &ClusterNode);
  if (EFI_ERROR (Status)) {
    ASSERT (0);
    return Status;
  }

  // Use the ClusterIndex for the _UID value as there is no AcpiProcessorUid
  // and EFI_ACPI_6_3_PPTT_PROCESSOR_ID_INVALID is set for non-Cpus.
  Status = AmlCodeGenNameInteger (
             "_UID",
             ClusterIndex,
             ClusterNode,
             NULL
             );
  if (EFI_ERROR (Status)) {
    ASSERT (0);
    return Status;
  }

  Status = AmlCodeGenNameString (
             "_HID",
             ACPI_HID_PROCESSOR_CONTAINER_DEVICE,
             ClusterNode,
             NULL
             );
  if (EFI_ERROR (Status)) {
    ASSERT (0);
    return Status;
  }

  // If a set of Lpi states are associated with the
  // CM_ARM_PROC_HIERARCHY_INFO, create an _LPI method returning them.
  if (ProcHierarchyNodeInfo->LpiToken != CM_NULL_TOKEN) {
    Status = CreateAmlLpiMethod (
               Generator,
               ProcHierarchyNodeInfo,
               ClusterNode
               );
    if (EFI_ERROR (Status)) {
      ASSERT (0);
      return Status;
    }
  }

  *ClusterNodePtr = ClusterNode;

  return Status;
}

/** Create an AML representation of the Cpu topology.

  A cluster is by extension any non-leave device in the cpu topology.

  @param [in] Generator          The SSDT Cpu Topology generator.
  @param [in] CfgMgrProtocol     Pointer to the Configuration Manager
                                 Protocol Interface.
  @param [in] NodeToken          Token of the CM_ARM_PROC_HIERARCHY_INFO
                                 currently handled.
                                 Cannot be CM_NULL_TOKEN.
  @param [in] ParentNode         Parent node to attach the created
                                 node to.

  @retval EFI_SUCCESS             Success.
  @retval EFI_INVALID_PARAMETER   Invalid parameter.
  @retval EFI_OUT_OF_RESOURCES    Failed to allocate memory.
**/
STATIC
EFI_STATUS
EFIAPI
CreateAmlCpuTopologyTree (
  IN        ACPI_CPU_TOPOLOGY_GENERATOR                   *Generator,
  IN  CONST EDKII_CONFIGURATION_MANAGER_PROTOCOL  *CONST  CfgMgrProtocol,
  IN        CM_OBJECT_TOKEN                               NodeToken,
  IN        AML_NODE_HANDLE                               ParentNode
  )
{
  EFI_STATUS              Status;
  UINT32                  Index;
  UINT32                  CpuIndex;
  UINT32                  ClusterIndex;
  AML_OBJECT_NODE_HANDLE  ClusterNode;

  ASSERT (Generator != NULL);
  ASSERT (Generator->ProcNodeList != NULL);
  ASSERT (Generator->ProcNodeCount != 0);
  ASSERT (CfgMgrProtocol != NULL);
  ASSERT (NodeToken != CM_NULL_TOKEN);
  ASSERT (ParentNode != NULL);

  CpuIndex     = 0;
  ClusterIndex = 0;

  for (Index = 0; Index < Generator->ProcNodeCount; Index++) {
    // Find the children of the CM_ARM_PROC_HIERARCHY_INFO
    // currently being handled (i.e. ParentToken == NodeToken).
    if (Generator->ProcNodeList[Index].ParentToken == NodeToken) {
      // Only Cpus (leaf nodes in this tree) have a GicCToken.
      // Create a Cpu node.
      if (Generator->ProcNodeList[Index].GicCToken != CM_NULL_TOKEN) {
        if ((Generator->ProcNodeList[Index].Flags & PPTT_PROCESSOR_MASK) !=
            PPTT_CPU_PROCESSOR_MASK)
        {
          DEBUG ((
            DEBUG_ERROR,
            "ERROR: SSDT-CPU-TOPOLOGY: Invalid flags for cpu: 0x%x.\n",
            Generator->ProcNodeList[Index].Flags
            ));
          ASSERT (0);
          return EFI_INVALID_PARAMETER;
        }

        Status = CreateAmlCpuFromProcHierarchy (
                   Generator,
                   CfgMgrProtocol,
                   ParentNode,
                   CpuIndex,
                   &Generator->ProcNodeList[Index]
                   );
        if (EFI_ERROR (Status)) {
          ASSERT (0);
          return Status;
        }

        CpuIndex++;
      } else {
        // If this is not a Cpu, then this is a cluster.

        // Acpi processor Id for clusters is not handled.
        if ((Generator->ProcNodeList[Index].Flags & PPTT_PROCESSOR_MASK) !=
            PPTT_CLUSTER_PROCESSOR_MASK)
        {
          DEBUG ((
            DEBUG_ERROR,
            "ERROR: SSDT-CPU-TOPOLOGY: Invalid flags for cluster: 0x%x.\n",
            Generator->ProcNodeList[Index].Flags
            ));
          ASSERT (0);
          return EFI_INVALID_PARAMETER;
        }

        Status = CreateAmlCluster (
                   Generator,
                   CfgMgrProtocol,
                   ParentNode,
                   &Generator->ProcNodeList[Index],
                   ClusterIndex,
                   &ClusterNode
                   );
        if (EFI_ERROR (Status)) {
          ASSERT (0);
          return Status;
        }

        // Nodes must have a unique name in the ASL namespace.
        // Reset the Cpu index whenever we create a new Cluster.
        ClusterIndex++;
        CpuIndex = 0;

        // Recursively continue creating an AML tree.
        Status = CreateAmlCpuTopologyTree (
                   Generator,
                   CfgMgrProtocol,
                   Generator->ProcNodeList[Index].Token,
                   ClusterNode
                   );
        if (EFI_ERROR (Status)) {
          ASSERT (0);
          return Status;
        }
      }
    } // if ParentToken == NodeToken
  } // for

  return EFI_SUCCESS;
}

/** Create the processor hierarchy AML tree from CM_ARM_PROC_HIERARCHY_INFO
    CM objects.

  @param [in] Generator        The SSDT Cpu Topology generator.
  @param [in] CfgMgrProtocol   Pointer to the Configuration Manager
                               Protocol Interface.
  @param [in] ScopeNode        Scope node handle ('\_SB' scope).

  @retval EFI_SUCCESS             Success.
  @retval EFI_INVALID_PARAMETER   Invalid parameter.
  @retval EFI_OUT_OF_RESOURCES    Failed to allocate memory.
**/
STATIC
EFI_STATUS
EFIAPI
CreateTopologyFromProcHierarchy (
  IN        ACPI_CPU_TOPOLOGY_GENERATOR                   *Generator,
  IN  CONST EDKII_CONFIGURATION_MANAGER_PROTOCOL  *CONST  CfgMgrProtocol,
  IN        AML_OBJECT_NODE_HANDLE                        ScopeNode
  )
{
  EFI_STATUS  Status;
  UINT32      Index;
  UINT32      TopLevelProcNodeIndex;

  ASSERT (Generator != NULL);
  ASSERT (Generator->ProcNodeCount != 0);
  ASSERT (Generator->ProcNodeList != NULL);
  ASSERT (CfgMgrProtocol != NULL);
  ASSERT (ScopeNode != NULL);

  TopLevelProcNodeIndex = MAX_UINT32;

  Status = TokenTableInitialize (Generator, Generator->ProcNodeCount);
  if (EFI_ERROR (Status)) {
    ASSERT (0);
    return Status;
  }

  // It is assumed that there is one unique CM_ARM_PROC_HIERARCHY_INFO
  // structure with no ParentToken and the EFI_ACPI_6_3_PPTT_PACKAGE_PHYSICAL
  // flag set. All other CM_ARM_PROC_HIERARCHY_INFO are non-physical and
  // have a ParentToken.
  for (Index = 0; Index < Generator->ProcNodeCount; Index++) {
    if ((Generator->ProcNodeList[Index].ParentToken == CM_NULL_TOKEN) &&
        (Generator->ProcNodeList[Index].Flags &
         EFI_ACPI_6_3_PPTT_PACKAGE_PHYSICAL))
    {
      if (TopLevelProcNodeIndex != MAX_UINT32) {
        DEBUG ((
          DEBUG_ERROR,
          "ERROR: SSDT-CPU-TOPOLOGY: Top level CM_ARM_PROC_HIERARCHY_INFO "
          "must be unique\n"
          ));
        ASSERT (0);
        goto exit_handler;
      }

      TopLevelProcNodeIndex = Index;
    }
  } // for

  Status = CreateAmlCpuTopologyTree (
             Generator,
             CfgMgrProtocol,
             Generator->ProcNodeList[TopLevelProcNodeIndex].Token,
             ScopeNode
             );
  if (EFI_ERROR (Status)) {
    ASSERT (0);
    goto exit_handler;
  }

  Status = GenerateLpiStates (Generator, CfgMgrProtocol, ScopeNode);
  if (EFI_ERROR (Status)) {
    ASSERT (0);
    goto exit_handler;
  }

exit_handler:
  TokenTableFree (Generator);
  return Status;
}

/** Create the processor hierarchy AML tree from CM_ARM_GICC_INFO
    CM objects.

  A cluster is by extension any non-leave device in the cpu topology.

  @param [in] Generator        The SSDT Cpu Topology generator.
  @param [in] CfgMgrProtocol   Pointer to the Configuration Manager
                               Protocol Interface.
  @param [in] ScopeNode        Scope node handle ('\_SB' scope).

  @retval EFI_SUCCESS             Success.
  @retval EFI_INVALID_PARAMETER   Invalid parameter.
  @retval EFI_OUT_OF_RESOURCES    Failed to allocate memory.
**/
STATIC
EFI_STATUS
EFIAPI
CreateTopologyFromGicC (
  IN        ACPI_CPU_TOPOLOGY_GENERATOR                   *Generator,
  IN  CONST EDKII_CONFIGURATION_MANAGER_PROTOCOL  *CONST  CfgMgrProtocol,
  IN        AML_OBJECT_NODE_HANDLE                        ScopeNode
  )
{
  EFI_STATUS        Status;
  CM_ARM_GICC_INFO  *GicCInfo;
  UINT32            GicCInfoCount;
  UINT32            Index;

  ASSERT (Generator != NULL);
  ASSERT (CfgMgrProtocol != NULL);
  ASSERT (ScopeNode != NULL);

  Status = GetEArmObjGicCInfo (
             CfgMgrProtocol,
             CM_NULL_TOKEN,
             &GicCInfo,
             &GicCInfoCount
             );
  if (EFI_ERROR (Status)) {
    ASSERT (0);
    return Status;
  }

  // For each CM_ARM_GICC_INFO object, create an AML node.
  for (Index = 0; Index < GicCInfoCount; Index++) {
    Status = CreateAmlCpu (
               Generator,
               ScopeNode,
               &GicCInfo[Index],
               Index,
               NULL
               );
    if (EFI_ERROR (Status)) {
      ASSERT (0);
      break;
    }
  } // for

  return Status;
}

/** Construct the SSDT Cpu Topology ACPI table.

  This function invokes the Configuration Manager protocol interface
  to get the required hardware information for generating the ACPI
  table.

  If this function allocates any resources then they must be freed
  in the FreeXXXXTableResources function.

  @param [in]  This           Pointer to the table generator.
  @param [in]  AcpiTableInfo  Pointer to the ACPI Table Info.
  @param [in]  CfgMgrProtocol Pointer to the Configuration Manager
                              Protocol Interface.
  @param [out] Table          Pointer to the constructed ACPI Table.

  @retval EFI_SUCCESS           Table generated successfully.
  @retval EFI_INVALID_PARAMETER A parameter is invalid.
  @retval EFI_NOT_FOUND         The required object was not found.
  @retval EFI_BAD_BUFFER_SIZE   The size returned by the Configuration
                                Manager is less than the Object size for the
                                requested object.
**/
STATIC
EFI_STATUS
EFIAPI
BuildSsdtCpuTopologyTable (
  IN  CONST ACPI_TABLE_GENERATOR                  *CONST  This,
  IN  CONST CM_STD_OBJ_ACPI_TABLE_INFO            *CONST  AcpiTableInfo,
  IN  CONST EDKII_CONFIGURATION_MANAGER_PROTOCOL  *CONST  CfgMgrProtocol,
  OUT       EFI_ACPI_DESCRIPTION_HEADER          **CONST  Table
  )
{
  EFI_STATUS                   Status;
  AML_ROOT_NODE_HANDLE         RootNode;
  AML_OBJECT_NODE_HANDLE       ScopeNode;
  CM_ARM_PROC_HIERARCHY_INFO   *ProcHierarchyNodeList;
  UINT32                       ProcHierarchyNodeCount;
  ACPI_CPU_TOPOLOGY_GENERATOR  *Generator;

  ASSERT (This != NULL);
  ASSERT (AcpiTableInfo != NULL);
  ASSERT (CfgMgrProtocol != NULL);
  ASSERT (Table != NULL);
  ASSERT (AcpiTableInfo->TableGeneratorId == This->GeneratorID);
  ASSERT (AcpiTableInfo->AcpiTableSignature == This->AcpiTableSignature);

  Generator = (ACPI_CPU_TOPOLOGY_GENERATOR *)This;

  Status = AddSsdtAcpiHeader (
             CfgMgrProtocol,
             This,
             AcpiTableInfo,
             &RootNode
             );
  if (EFI_ERROR (Status)) {
    return Status;
  }

  Status = AmlCodeGenScope (SB_SCOPE, RootNode, &ScopeNode);
  if (EFI_ERROR (Status)) {
    goto exit_handler;
  }

  // Get the processor hierarchy info and update the processor topology
  // structure count with Processor Hierarchy Nodes (Type 0)
  Status = GetEArmObjProcHierarchyInfo (
             CfgMgrProtocol,
             CM_NULL_TOKEN,
             &ProcHierarchyNodeList,
             &ProcHierarchyNodeCount
             );
  if (EFI_ERROR (Status) &&
      (Status != EFI_NOT_FOUND))
  {
    goto exit_handler;
  }

  if (Status == EFI_NOT_FOUND) {
    // If hierarchy information is not found generate a flat topology
    // using CM_ARM_GICC_INFO objects.
    Status = CreateTopologyFromGicC (
               Generator,
               CfgMgrProtocol,
               ScopeNode
               );
    if (EFI_ERROR (Status)) {
      goto exit_handler;
    }
  } else {
    // Generate the topology from CM_ARM_PROC_HIERARCHY_INFO objects.
    Generator->ProcNodeList  = ProcHierarchyNodeList;
    Generator->ProcNodeCount = ProcHierarchyNodeCount;

    Status = CreateTopologyFromProcHierarchy (
               Generator,
               CfgMgrProtocol,
               ScopeNode
               );
    if (EFI_ERROR (Status)) {
      goto exit_handler;
    }
  }

  Status = AmlSerializeDefinitionBlock (
             RootNode,
             Table
             );
  if (EFI_ERROR (Status)) {
    DEBUG ((
      DEBUG_ERROR,
      "ERROR: SSDT-CPU-TOPOLOGY: Failed to Serialize SSDT Table Data."
      " Status = %r\n",
      Status
      ));
    goto exit_handler;
  }

exit_handler:
  // Delete the RootNode and its attached children.
  return AmlDeleteTree (RootNode);
}

/** Free any resources allocated for constructing the
    SSDT Cpu Topology ACPI table.

  @param [in]      This           Pointer to the table generator.
  @param [in]      AcpiTableInfo  Pointer to the ACPI Table Info.
  @param [in]      CfgMgrProtocol Pointer to the Configuration Manager
                                  Protocol Interface.
  @param [in, out] Table          Pointer to the ACPI Table.

  @retval EFI_SUCCESS           The resources were freed successfully.
  @retval EFI_INVALID_PARAMETER The table pointer is NULL or invalid.
**/
STATIC
EFI_STATUS
FreeSsdtCpuTopologyTableResources (
  IN      CONST ACPI_TABLE_GENERATOR                  *CONST  This,
  IN      CONST CM_STD_OBJ_ACPI_TABLE_INFO            *CONST  AcpiTableInfo,
  IN      CONST EDKII_CONFIGURATION_MANAGER_PROTOCOL  *CONST  CfgMgrProtocol,
  IN OUT        EFI_ACPI_DESCRIPTION_HEADER          **CONST  Table
  )
{
  ASSERT (This != NULL);
  ASSERT (AcpiTableInfo != NULL);
  ASSERT (CfgMgrProtocol != NULL);
  ASSERT (AcpiTableInfo->TableGeneratorId == This->GeneratorID);
  ASSERT (AcpiTableInfo->AcpiTableSignature == This->AcpiTableSignature);

  if ((Table == NULL) || (*Table == NULL)) {
    DEBUG ((DEBUG_ERROR, "ERROR: SSDT-CPU-TOPOLOGY: Invalid Table Pointer\n"));
    ASSERT ((Table != NULL) && (*Table != NULL));
    return EFI_INVALID_PARAMETER;
  }

  FreePool (*Table);
  *Table = NULL;
  return EFI_SUCCESS;
}

/** This macro defines the SSDT Cpu Topology Table Generator revision.
*/
#define SSDT_CPU_TOPOLOGY_GENERATOR_REVISION  CREATE_REVISION (1, 0)

/** The interface for the SSDT Cpu Topology Table Generator.
*/
STATIC
ACPI_CPU_TOPOLOGY_GENERATOR  SsdtCpuTopologyGenerator = {
  // ACPI table generator header
  {
    // Generator ID
    CREATE_STD_ACPI_TABLE_GEN_ID (EStdAcpiTableIdSsdtCpuTopology),
    // Generator Description
    L"ACPI.STD.SSDT.CPU.TOPOLOGY.GENERATOR",
    // ACPI Table Signature
    EFI_ACPI_6_3_SECONDARY_SYSTEM_DESCRIPTION_TABLE_SIGNATURE,
    // ACPI Table Revision - Unused
    0,
    // Minimum ACPI Table Revision - Unused
    0,
    // Creator ID
    TABLE_GENERATOR_CREATOR_ID_ARM,
    // Creator Revision
    SSDT_CPU_TOPOLOGY_GENERATOR_REVISION,
    // Build Table function
    BuildSsdtCpuTopologyTable,
    // Free Resource function
    FreeSsdtCpuTopologyTableResources,
    // Extended build function not needed
    NULL,
    // Extended build function not implemented by the generator.
    // Hence extended free resource function is not required.
    NULL
  },

  // Private fields are defined from here.

  // TokenTable
  {
    // Table
    NULL,
    // LastIndex
    0
  },
  // ProcNodeList
  NULL,
  // ProcNodeCount
  0
};

/** Register the Generator with the ACPI Table Factory.

  @param [in]  ImageHandle  The handle to the image.
  @param [in]  SystemTable  Pointer to the System Table.

  @retval EFI_SUCCESS           The Generator is registered.
  @retval EFI_INVALID_PARAMETER A parameter is invalid.
  @retval EFI_ALREADY_STARTED   The Generator for the Table ID
                                is already registered.
**/
EFI_STATUS
EFIAPI
AcpiSsdtCpuTopologyLibConstructor (
  IN  EFI_HANDLE        ImageHandle,
  IN  EFI_SYSTEM_TABLE  *SystemTable
  )
{
  EFI_STATUS  Status;

  Status = RegisterAcpiTableGenerator (&SsdtCpuTopologyGenerator.Header);
  DEBUG ((
    DEBUG_INFO,
    "SSDT-CPU-TOPOLOGY: Register Generator. Status = %r\n",
    Status
    ));
  ASSERT_EFI_ERROR (Status);

  return Status;
}

/** Deregister the Generator from the ACPI Table Factory.

  @param [in]  ImageHandle  The handle to the image.
  @param [in]  SystemTable  Pointer to the System Table.

  @retval EFI_SUCCESS           The Generator is deregistered.
  @retval EFI_INVALID_PARAMETER A parameter is invalid.
  @retval EFI_NOT_FOUND         The Generator is not registered.
**/
EFI_STATUS
EFIAPI
AcpiSsdtCpuTopologyLibDestructor (
  IN  EFI_HANDLE        ImageHandle,
  IN  EFI_SYSTEM_TABLE  *SystemTable
  )
{
  EFI_STATUS  Status;

  Status = DeregisterAcpiTableGenerator (&SsdtCpuTopologyGenerator.Header);
  DEBUG ((
    DEBUG_INFO,
    "SSDT-CPU-TOPOLOGY: Deregister Generator. Status = %r\n",
    Status
    ));
  ASSERT_EFI_ERROR (Status);
  return Status;
}
