DynamicTablesPkg: Add ETE device to CPU node in AML

The Coresight Embedded Trace Extension (ETE) feature
can be detected by the platform firmware by examining
the debug feature register ID_AA64DFR0_EL1.TraceVer
field.
The platform configuration manager can then describe
the ETE by creating CM_ARM_ET_INFO object(s) and
referencing these in CM_ARM_GICC_INFO.EtToken.

The 'Table 3: Compatible IDs for architected
CoreSight components' in the 'ACPI for CoreSight
1.2 Platform Design Document' specifies the HID
value for Coresight ETE and CoreSight Embedded
Trace Macrocell (ETM) v4.x as ARMH C500.

Therefore, update the SsdtCpuTopologyGenerator
to add an ETE device to the CPU node in the AML
CPU hierarchy so that an OS can utilise this
information.

Note: Although ETE and ETM share the same HID,
ETE has a system register interfaces, unlike
ETM which requires memory mapped registers.
Since this patch aims to support ETE, the AML
description does not describe any memory mapped
registers. However, support for ETM can be
added in the future.

Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
Reviewed-by: Pierre Gondois  <pierre.gondois@arm.com>

DynamicTablesPkg/Library/Acpi/Arm/AcpiSsdtCpuTopologyLibArm/SsdtCpuTopologyGenerator.c

@@ -1,11 +1,17 @@
 /** @file
   SSDT Cpu Topology Table Generator.
 
-  Copyright (c) 2021, Arm Limited. All rights reserved.<BR>
+  Copyright (c) 2021 - 2023, 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
+    - ACPI for CoreSight version 1.2 Platform Design Document
+      (https://developer.arm.com/documentation/den0067/a/?lang=en)
+
+  @par Glossary:
+    - ETE - Embedded Trace Extension.
+    - ETM - Embedded Trace Macrocell.
 **/
 
 #include <Library/AcpiLib.h>
@@ -35,6 +41,7 @@
   - EArmObjProcHierarchyInfo (OPTIONAL) along with
   - EArmObjCmRef (OPTIONAL)
   - EArmObjLpiInfo (OPTIONAL)
+  - GetEArmObjEtInfo (OPTIONAL)
 */
 
 /** This macro expands to a function that retrieves the GIC
@@ -86,6 +93,16 @@ GET_OBJECT_LIST (
   CM_ARM_CPC_INFO
   );
 
+/**
+  This macro expands to a function that retrieves the ET device
+  information from the Configuration Manager.
+*/
+GET_OBJECT_LIST (
+  EObjNameSpaceArm,
+  EArmObjEtInfo,
+  CM_ARM_ET_INFO
+  );
+
 /** Initialize the TokenTable.
 
   One entry should be allocated for each CM_ARM_PROC_HIERARCHY_INFO
@@ -326,6 +343,144 @@ CreateAmlCpcNode (
   return Status;
 }
 
+/** Create an embedded trace device and add it to the Cpu Node in the
+    AML namespace.
+
+  This generates the following ASL code:
+  Device (E002)
+  {
+      Name (_UID, 2)
+      Name (_HID, "ARMHC500")
+  }
+
+  Note: Currently we only support generating ETE nodes. Unlike ETM,
+  ETE has a system register interface and therefore does not need
+  the MMIO range to be described.
+
+  @param [in]  Generator    The SSDT Cpu Topology generator.
+  @param [in]  ParentNode   Parent node to attach the Cpu node to.
+  @param [in]  CpuName      Value used to generate the node name.
+  @param [out] EtNodePtr   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
+CreateAmlEtd (
+  IN   ACPI_CPU_TOPOLOGY_GENERATOR  *Generator,
+  IN   AML_NODE_HANDLE              ParentNode,
+  IN   UINT32                       CpuName,
+  OUT  AML_OBJECT_NODE_HANDLE       *EtNodePtr OPTIONAL
+  )
+{
+  EFI_STATUS              Status;
+  AML_OBJECT_NODE_HANDLE  EtNode;
+  CHAR8                   AslName[AML_NAME_SEG_SIZE + 1];
+
+  ASSERT (Generator != NULL);
+  ASSERT (ParentNode != NULL);
+
+  Status = WriteAslName ('E', CpuName, AslName);
+  if (EFI_ERROR (Status)) {
+    ASSERT (0);
+    return Status;
+  }
+
+  Status = AmlCodeGenDevice (AslName, ParentNode, &EtNode);
+  if (EFI_ERROR (Status)) {
+    ASSERT (0);
+    return Status;
+  }
+
+  Status = AmlCodeGenNameInteger (
+             "_UID",
+             CpuName,
+             EtNode,
+             NULL
+             );
+  if (EFI_ERROR (Status)) {
+    ASSERT (0);
+    return Status;
+  }
+
+  Status = AmlCodeGenNameString (
+             "_HID",
+             ACPI_HID_ET_DEVICE,
+             EtNode,
+             NULL
+             );
+  if (EFI_ERROR (Status)) {
+    ASSERT (0);
+    return Status;
+  }
+
+  // If requested, return the handle to the EtNode.
+  if (EtNodePtr != NULL) {
+    *EtNodePtr = EtNode;
+  }
+
+  return Status;
+}
+
+/** Create and add an Embedded trace device to the Cpu Node.
+
+  @param [in]  Generator              The SSDT Cpu Topology generator.
+  @param [in]  CfgMgrProtocol         Pointer to the Configuration Manager
+                                      Protocol Interface.
+  @param [in]  GicCInfo               Pointer to the CM_ARM_GICC_INFO object
+                                      describing the Cpu.
+  @param [in]  CpuName                Value used to generate the CPU node name.
+  @param [in]  Node                   CPU Node to which the ET device node is
+                                      attached.
+
+  @retval EFI_SUCCESS             The function completed successfully.
+  @retval EFI_UNSUPPORTED         Feature Unsupported.
+  @retval EFI_INVALID_PARAMETER   Invalid parameter.
+  @retval EFI_OUT_OF_RESOURCES    Failed to allocate memory.
+**/
+STATIC
+EFI_STATUS
+EFIAPI
+CreateAmlEtNode (
+  IN  ACPI_CPU_TOPOLOGY_GENERATOR                         *Generator,
+  IN  CONST EDKII_CONFIGURATION_MANAGER_PROTOCOL  *CONST  CfgMgrProtocol,
+  IN  CM_ARM_GICC_INFO                                    *GicCInfo,
+  IN        UINT32                                        CpuName,
+  IN  AML_OBJECT_NODE_HANDLE                              *Node
+  )
+{
+  EFI_STATUS      Status;
+  CM_ARM_ET_INFO  *EtInfo;
+
+  Status = GetEArmObjEtInfo (
+             CfgMgrProtocol,
+             GicCInfo->EtToken,
+             &EtInfo,
+             NULL
+             );
+  if (EFI_ERROR (Status)) {
+    ASSERT (0);
+    return Status;
+  }
+
+  // Currently we only support creation of a ETE Node.
+  if (EtInfo->EtType != ArmEtTypeEte) {
+    return EFI_UNSUPPORTED;
+  }
+
+  Status = CreateAmlEtd (
+             Generator,
+             Node,
+             CpuName,
+             NULL
+             );
+  ASSERT_EFI_ERROR (Status);
+  return Status;
+}
+
 /** Create and add an _LPI method to Cpu/Cluster Node.
 
   For instance, transform an AML node from:
@@ -694,6 +849,21 @@ CreateAmlCpuFromProcHierarchy (
     }
   }
 
+  // Add an Embedded Trace node if present.
+  if (GicCInfo->EtToken != CM_NULL_TOKEN) {
+    Status = CreateAmlEtNode (
+               Generator,
+               CfgMgrProtocol,
+               GicCInfo,
+               CpuName,
+               CpuNode
+               );
+    if (EFI_ERROR (Status)) {
+      ASSERT_EFI_ERROR (Status);
+      return Status;
+    }
+  }
+
   return Status;
 }
 
@@ -1135,6 +1305,20 @@ CreateTopologyFromGicC (
         break;
       }
     }
+
+    if (GicCInfo[Index].EtToken != CM_NULL_TOKEN) {
+      Status = CreateAmlEtNode (
+                 Generator,
+                 CfgMgrProtocol,
+                 &GicCInfo[Index],
+                 Index,
+                 CpuNode
+                 );
+      if (EFI_ERROR (Status)) {
+        ASSERT_EFI_ERROR (Status);
+        return Status;
+      }
+    }
   } // for
 
   return Status;

DynamicTablesPkg/Library/Acpi/Arm/AcpiSsdtCpuTopologyLibArm/SsdtCpuTopologyGenerator.h

@@ -1,11 +1,17 @@
 /** @file
   SSDT Cpu Topology Table Generator.
 
-  Copyright (c) 2021, Arm Limited. All rights reserved.<BR>
+  Copyright (c) 2021 - 2023, 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
+    - ACPI for CoreSight version 1.2 Platform Design Document
+      (https://developer.arm.com/documentation/den0067/a/?lang=en)
+
+  @par Glossary:
+    - ETE - Embedded Trace Extension.
+    - ETM - Embedded Trace Macrocell.
 **/
 
 #ifndef SSDT_CPU_TOPOLOGY_GENERATOR_H_
@@ -49,6 +55,9 @@
 /// HID for a processor device.
 #define ACPI_HID_PROCESSOR_DEVICE  "ACPI0007"
 
+/// HID for a ETM/ETE device.
+#define ACPI_HID_ET_DEVICE  "ARMHC500"
+
 /// HID for a processor container device.
 #define ACPI_HID_PROCESSOR_CONTAINER_DEVICE  "ACPI0010"