Re: [PATCH v2 11/21] DynamicTablesPkg: AML Code generation for Resource data EndTag


Sami Mujawar
 

Hi Pierre,

This patch looks good to me.

Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>

Regards,

Sami Mujawar

On 07/10/2021 04:32 PM, Pierre.Gondois@arm.com wrote:
From: Pierre Gondois <Pierre.Gondois@arm.com>

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.

Signed-off-by: Pierre Gondois <Pierre.Gondois@arm.com>
---
.../AmlLib/CodeGen/AmlResourceDataCodeGen.c | 113 ++++++++++++++++++
.../AmlLib/CodeGen/AmlResourceDataCodeGen.h | 43 +++++++
2 files changed, 156 insertions(+)

diff --git a/DynamicTablesPkg/Library/Common/AmlLib/CodeGen/AmlResourceDataCodeGen.c b/DynamicTablesPkg/Library/Common/AmlLib/CodeGen/AmlResourceDataCodeGen.c
index 20b745f27a2b..0bdb6c24c5bb 100644
--- a/DynamicTablesPkg/Library/Common/AmlLib/CodeGen/AmlResourceDataCodeGen.c
+++ b/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

diff --git a/DynamicTablesPkg/Library/Common/AmlLib/CodeGen/AmlResourceDataCodeGen.h b/DynamicTablesPkg/Library/Common/AmlLib/CodeGen/AmlResourceDataCodeGen.h
index 831d6a7462ae..102340495933 100644
--- a/DynamicTablesPkg/Library/Common/AmlLib/CodeGen/AmlResourceDataCodeGen.h
+++ b/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_
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