DynamicTablesPkg: AML code generation for a ResourceTemplate

ASL provides a ResourceTemplate macro that creates a Buffer in which
resource descriptor macros can be listed. The ResourceTemplate macro
automatically generates an End descriptor and calculates the checksum
for the resource template.

Therefore, add AmlCodeGenResourceTemplate() to generate AML code for
the ResourceTemplate() macro. This function generates a Buffer node
with an EndTag resource data descriptor, which is similar to the ASL
ResourceTemplate() macro.

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

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

@@ -12,6 +12,7 @@
 
 #include <AmlCoreInterface.h>
 #include <AmlEncoding/Aml.h>
+#include <CodeGen/AmlResourceDataCodeGen.h>
 #include <Tree/AmlNode.h>
 #include <Tree/AmlTree.h>
 #include <String/AmlString.h>
@@ -316,6 +317,195 @@ error_handler:
   return Status;
 }
 
+/** AML code generation for a Buffer object node.
+
+  To create a Buffer object node with an empty buffer,
+  call the function with (Buffer=NULL, BufferSize=0).
+
+  @param [in]  Buffer          Buffer to set for the created Buffer
+                               object node. The Buffer's content is copied.
+                               NULL if there is no buffer to set for
+                               the Buffer node.
+  @param [in]  BufferSize      Size of the Buffer.
+                               0 if there is no buffer to set for
+                               the Buffer node.
+  @param [out] NewObjectNode   If success, contains the created
+                               Buffer object node.
+
+  @retval EFI_SUCCESS             Success.
+  @retval EFI_INVALID_PARAMETER   Invalid parameter.
+  @retval EFI_OUT_OF_RESOURCES    Failed to allocate memory.
+**/
+STATIC
+EFI_STATUS
+EFIAPI
+AmlCodeGenBuffer (
+  IN  CONST UINT8             * Buffer,       OPTIONAL
+  IN        UINT32              BufferSize,   OPTIONAL
+  OUT       AML_OBJECT_NODE  ** NewObjectNode
+  )
+{
+  EFI_STATUS        Status;
+  AML_OBJECT_NODE * BufferNode;
+  AML_OBJECT_NODE * BufferSizeNode;
+  UINT32            BufferSizeNodeSize;
+  AML_DATA_NODE   * DataNode;
+  UINT32            PkgLen;
+
+  // Buffer and BufferSize must be either both set, or both clear.
+  if ((NewObjectNode == NULL)                 ||
+      ((Buffer == NULL) != (BufferSize == 0))) {
+    ASSERT (0);
+    return EFI_INVALID_PARAMETER;
+  }
+
+  BufferNode = NULL;
+  DataNode = NULL;
+
+  // Cf ACPI 6.3 specification, s20.2.5.4 "Type 2 Opcodes Encoding"
+  // DefBuffer := BufferOp PkgLength BufferSize ByteList
+  // BufferOp  := 0x11
+  // BufferSize := TermArg => Integer
+
+  Status = AmlCodeGenInteger (BufferSize, &BufferSizeNode);
+  if (EFI_ERROR (Status)) {
+    ASSERT (0);
+    return Status;
+  }
+
+  // Get the number of bytes required to encode the BufferSizeNode.
+  Status = AmlComputeSize (
+             (AML_NODE_HEADER*)BufferSizeNode,
+             &BufferSizeNodeSize
+             );
+  if (EFI_ERROR (Status)) {
+    ASSERT (0);
+    goto error_handler;
+  }
+
+  // Compute the size to write in the PkgLen.
+  Status = AmlComputePkgLength (BufferSizeNodeSize + BufferSize, &PkgLen);
+  if (EFI_ERROR (Status)) {
+    ASSERT (0);
+    goto error_handler;
+  }
+
+  // Create an object node for the buffer.
+  Status = AmlCreateObjectNode (
+             AmlGetByteEncodingByOpCode (AML_BUFFER_OP, 0),
+             PkgLen,
+             &BufferNode
+             );
+  if (EFI_ERROR (Status)) {
+    ASSERT (0);
+    goto error_handler;
+  }
+
+  // Set the BufferSizeNode as a fixed argument of the BufferNode.
+  Status = AmlSetFixedArgument (
+             BufferNode,
+             EAmlParseIndexTerm0,
+             (AML_NODE_HEADER*)BufferSizeNode
+             );
+  if (EFI_ERROR (Status)) {
+    ASSERT (0);
+    goto error_handler;
+  }
+
+  // BufferSizeNode is now attached.
+  BufferSizeNode = NULL;
+
+  // If there is a buffer, create a DataNode and attach it to the BufferNode.
+  if (Buffer != NULL) {
+    Status = AmlCreateDataNode (
+               EAmlNodeDataTypeRaw,
+               Buffer,
+               BufferSize,
+               &DataNode
+               );
+    if (EFI_ERROR (Status)) {
+      ASSERT (0);
+      goto error_handler;
+    }
+
+    Status = AmlVarListAddTail (
+               (AML_NODE_HEADER*)BufferNode,
+               (AML_NODE_HEADER*)DataNode
+               );
+    if (EFI_ERROR (Status)) {
+      ASSERT (0);
+      goto error_handler;
+    }
+  }
+
+  *NewObjectNode = BufferNode;
+  return Status;
+
+error_handler:
+  if (BufferSizeNode != NULL) {
+    AmlDeleteTree ((AML_NODE_HEADER*)BufferSizeNode);
+  }
+  if (BufferNode != NULL) {
+    AmlDeleteTree ((AML_NODE_HEADER*)BufferNode);
+  }
+  if (DataNode != NULL) {
+    AmlDeleteTree ((AML_NODE_HEADER*)DataNode);
+  }
+  return Status;
+}
+
+/** AML code generation for a ResourceTemplate.
+
+  "ResourceTemplate" is a macro defined in ACPI 6.3, s19.3.3
+  "ASL Resource Templates". It allows to store resource data elements.
+
+  In AML, a ResourceTemplate is implemented as a Buffer storing resource
+  data elements. An EndTag resource data descriptor must be at the end
+  of the list of resource data elements.
+  This function generates a Buffer node with an EndTag resource data
+  descriptor. It can be seen as an empty list of resource data elements.
+
+  @param [out] NewObjectNode   If success, contains the created
+                               ResourceTemplate object node.
+
+  @retval EFI_SUCCESS             Success.
+  @retval EFI_INVALID_PARAMETER   Invalid parameter.
+  @retval EFI_OUT_OF_RESOURCES    Failed to allocate memory.
+**/
+STATIC
+EFI_STATUS
+EFIAPI
+AmlCodeGenResourceTemplate (
+  OUT AML_OBJECT_NODE    ** NewObjectNode
+  )
+{
+  EFI_STATUS          Status;
+  AML_OBJECT_NODE   * BufferNode;
+
+  if (NewObjectNode == NULL) {
+    ASSERT (0);
+    return EFI_INVALID_PARAMETER;
+  }
+
+  // Create a BufferNode with an empty buffer.
+  Status = AmlCodeGenBuffer (NULL, 0, &BufferNode);
+  if (EFI_ERROR (Status)) {
+    ASSERT (0);
+    return Status;
+  }
+
+  // Create an EndTag resource data element and attach it to the Buffer.
+  Status = AmlCodeGenEndTag (0, BufferNode, NULL);
+  if (EFI_ERROR (Status)) {
+    ASSERT (0);
+    AmlDeleteTree ((AML_NODE_HEADER*)BufferNode);
+    return Status;
+  }
+
+  *NewObjectNode = BufferNode;
+  return Status;
+}
+
 /** AML code generation for a Name object node.
 
   @param  [in] NameString     The new variable name.