DynamicTablesPkg: AML Code generation for Resource data EndTag

Add a helper function AmlCodeGenEndTag() to generate AML Resource Data
EndTag. The EndTag resource data is automatically generated by the ASL
compiler at the end of a list of resource data elements. Therefore, an
equivalent function is not present in ASL.

However, AmlCodeGenEndTag() is useful when generating AML code for the
ResourceTemplate() macro.

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

DynamicTablesPkg/Library/Common/AmlLib/CodeGen/AmlResourceDataCodeGen.c

@@ -280,6 +280,119 @@ AmlCodeGenRdRegister (
   return LinkRdNode (RdNode, NameOpNode, NewRdNode);
 }
 
+/** Code generation for the EndTag resource data.
+
+  The EndTag resource data is automatically generated by the ASL compiler
+  at the end of a list of resource data elements. Thus, it doesn't have
+  a corresponding ASL function.
+
+  This function allocates memory to create a data node. It is the caller's
+  responsibility to either:
+   - attach this node to an AML tree;
+   - delete this node.
+
+  ACPI 6.4, s6.4.2.9 "End Tag":
+  "This checksum is generated such that adding it to the sum of all the data
+  bytes will produce a zero sum."
+  "If the checksum field is zero, the resource data is treated as if the
+  checksum operation succeeded. Configuration proceeds normally."
+
+  To avoid re-computing checksums, if a new resource data elements is
+  added/removed/modified in a list of resource data elements, the AmlLib
+  resets the checksum to 0.
+
+  @param [in]  CheckSum        CheckSum to store in the EndTag.
+                               To ignore/avoid computing the checksum,
+                               give 0.
+  @param [in]  ParentNode      If not NULL, add the generated node
+                               to the end of the variable list of
+                               argument of the ParentNode.
+                               The ParentNode must not initially contain
+                               an EndTag resource data element.
+  @param  [out] NewRdNode      If success, contains the generated node.
+
+  @retval EFI_SUCCESS             The function completed successfully.
+  @retval EFI_INVALID_PARAMETER   Invalid parameter.
+  @retval EFI_OUT_OF_RESOURCES    Could not allocate memory.
+**/
+EFI_STATUS
+EFIAPI
+AmlCodeGenEndTag (
+  IN  UINT8               CheckSum,   OPTIONAL
+  IN  AML_OBJECT_NODE   * ParentNode, OPTIONAL
+  OUT AML_DATA_NODE    ** NewRdNode   OPTIONAL
+  )
+{
+  EFI_STATUS                      Status;
+  AML_DATA_NODE                 * RdNode;
+  EFI_ACPI_END_TAG_DESCRIPTOR     EndTag;
+  ACPI_SMALL_RESOURCE_HEADER      SmallResHdr;
+
+  if ((ParentNode == NULL) && (NewRdNode == NULL)) {
+    ASSERT (0);
+    return EFI_INVALID_PARAMETER;
+  }
+
+  RdNode = NULL;
+
+  // Header
+  SmallResHdr.Bits.Length = sizeof (EFI_ACPI_END_TAG_DESCRIPTOR) -
+                              sizeof (ACPI_SMALL_RESOURCE_HEADER);
+  SmallResHdr.Bits.Name = ACPI_SMALL_END_TAG_DESCRIPTOR_NAME;
+  SmallResHdr.Bits.Type = ACPI_SMALL_ITEM_FLAG;
+
+  // Body
+  EndTag.Desc = SmallResHdr.Byte;
+  EndTag.Checksum = CheckSum;
+
+  Status = AmlCreateDataNode (
+             EAmlNodeDataTypeResourceData,
+             (UINT8*)&EndTag,
+             sizeof (EFI_ACPI_END_TAG_DESCRIPTOR),
+             &RdNode
+             );
+  if (EFI_ERROR (Status)) {
+    ASSERT (0);
+    return Status;
+  }
+
+  if (NewRdNode != NULL) {
+    *NewRdNode = RdNode;
+  }
+
+  if (ParentNode != NULL) {
+    // Check the BufferOp doesn't contain any resource data yet.
+    // This is a hard check: do not allow to add an EndTag if the BufferNode
+    // already has resource data elements attached. Indeed, the EndTag should
+    // have already been added.
+    if (AmlGetNextVariableArgument ((AML_NODE_HEADER*)ParentNode, NULL) !=
+          NULL) {
+      ASSERT (0);
+      Status = EFI_INVALID_PARAMETER;
+      goto error_handler;
+    }
+
+    // Add the EndTag RdNode. Indeed, the AmlAppendRdNode function
+    // is looking for an EndTag, which we are adding here.
+    Status = AmlVarListAddTail (
+               (AML_NODE_HEADER*)ParentNode,
+               (AML_NODE_HEADER*)RdNode
+               );
+    if (EFI_ERROR (Status)) {
+      ASSERT (0);
+      goto error_handler;
+    }
+  }
+
+  return Status;
+
+error_handler:
+  if (RdNode != NULL) {
+    AmlDeleteTree ((AML_NODE_HEADER*)RdNode);
+  }
+  return Status;
+}
+
 // DEPRECATED APIS
 #ifndef DISABLE_NEW_DEPRECATED_INTERFACES
 

DynamicTablesPkg/Library/Common/AmlLib/CodeGen/AmlResourceDataCodeGen.h

@@ -104,4 +104,47 @@ AmlCodeGenRdRegister (
   OUT AML_DATA_NODE_HANDLE    *NewRdNode  OPTIONAL
   );
 
+/** Code generation for the EndTag resource data.
+
+  The EndTag resource data is automatically generated by the ASL compiler
+  at the end of a list of resource data elements. Thus, it doesn't have
+  a corresponding ASL function.
+
+  This function allocates memory to create a data node. It is the caller's
+  responsibility to either:
+   - attach this node to an AML tree;
+   - delete this node.
+
+  ACPI 6.4, s6.4.2.9 "End Tag":
+  "This checksum is generated such that adding it to the sum of all the data
+  bytes will produce a zero sum."
+  "If the checksum field is zero, the resource data is treated as if the
+  checksum operation succeeded. Configuration proceeds normally."
+
+  To avoid re-computing checksums, if a new resource data elements is
+  added/removed/modified in a list of resource data elements, the AmlLib
+  resets the checksum to 0.
+
+  @param [in]  CheckSum        CheckSum to store in the EndTag.
+                               To ignore/avoid computing the checksum,
+                               give 0.
+  @param [in]  ParentNode      If not NULL, add the generated node
+                               to the end of the variable list of
+                               argument of the ParentNode.
+                               The ParentNode must not initially contain
+                               an EndTag resource data element.
+  @param  [out] NewRdNode      If success, contains the generated node.
+
+  @retval EFI_SUCCESS             The function completed successfully.
+  @retval EFI_INVALID_PARAMETER   Invalid parameter.
+  @retval EFI_OUT_OF_RESOURCES    Could not allocate memory.
+**/
+EFI_STATUS
+EFIAPI
+AmlCodeGenEndTag (
+  IN  UINT8               CheckSum,   OPTIONAL
+  IN  AML_OBJECT_NODE   * ParentNode, OPTIONAL
+  OUT AML_DATA_NODE    ** NewRdNode   OPTIONAL
+  );
+
 #endif // AML_RESOURCE_DATA_CODE_GEN_H_