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DynamicTablesPkg: Add AmlSetRdListCheckSum() 

Lists of Resource Data elements end with an EndTag (most of the time).
This function finds the EndTag (if present) in a list of Resource Data
elements and sets the checksum.

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."

Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>
Signed-off-by: Pierre Gondois <Pierre.Gondois@arm.com>
This commit is contained in:
Pierre Gondois 2021-10-08 15:46:16 +01:00 committed by mergify[bot]
parent 28b2df475f
commit 74addfeab6
2 changed files with 108 additions and 0 deletions
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76
DynamicTablesPkg/Library/Common/AmlLib/Utils/AmlUtility.c
View File

@ -904,3 +904,79 @@ AmlPropagateInformation (
return EFI_SUCCESS;
}
/** Find and set the EndTag's Checksum of a list of Resource Data elements.
Lists of Resource Data elements end with an EndTag (most of the time). This
function finds the EndTag (if present) in a list of Resource Data elements
and sets the checksum.
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] BufferOpNode Node having a list of Resource Data elements.
@param [in] CheckSum CheckSum to store in the EndTag.
To ignore/avoid computing the checksum,
give 0.
@retval EFI_SUCCESS The function completed successfully.
@retval EFI_INVALID_PARAMETER Invalid parameter.
@retval EFI_NOT_FOUND No EndTag found.
**/
EFI_STATUS
EFIAPI
AmlSetRdListCheckSum (
IN AML_OBJECT_NODE * BufferOpNode,
IN UINT8 CheckSum
)
{
EFI_STATUS Status;
AML_DATA_NODE * LastRdNode;
AML_RD_HEADER RdDataType;
if (!AmlNodeCompareOpCode (BufferOpNode, AML_BUFFER_OP, 0)) {
ASSERT (0);
return EFI_INVALID_PARAMETER;
}
// Get the last Resource data node in the variable list of
// argument of the BufferOp node.
LastRdNode = (AML_DATA_NODE*)AmlGetPreviousVariableArgument (
(AML_NODE_HEADER*)BufferOpNode,
NULL
);
if ((LastRdNode == NULL) ||
!IS_AML_DATA_NODE (LastRdNode) ||
(LastRdNode->DataType != EAmlNodeDataTypeResourceData)) {
ASSERT (0);
return EFI_INVALID_PARAMETER;
}
Status = AmlGetResourceDataType (LastRdNode, &RdDataType);
if (EFI_ERROR (Status)) {
ASSERT (0);
return Status;
}
// Check the LastRdNode is an EndTag.
// It is possible to have only one Resource Data in a BufferOp with
// no EndTag. Return EFI_NOT_FOUND is such case.
if (!AmlRdCompareDescId (
&RdDataType,
AML_RD_BUILD_SMALL_DESC_ID (ACPI_SMALL_END_TAG_DESCRIPTOR_NAME))) {
ASSERT (0);
return EFI_NOT_FOUND;
}
Status = AmlRdSetEndTagChecksum (LastRdNode->Buffer, CheckSum);
ASSERT_EFI_ERROR (Status);
return Status;
}

32
DynamicTablesPkg/Library/Common/AmlLib/Utils/AmlUtility.h
View File

@ -91,5 +91,37 @@ AmlPropagateInformation (
IN UINT8 NodeCount
);
/** Find and set the EndTag's Checksum of a list of Resource Data elements.
Lists of Resource Data elements end with an EndTag (most of the time). This
function finds the EndTag (if present) in a list of Resource Data elements
and sets the checksum.
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] BufferOpNode Node having a list of Resource Data elements.
@param [in] CheckSum CheckSum to store in the EndTag.
To ignore/avoid computing the checksum,
give 0.
@retval EFI_SUCCESS The function completed successfully.
@retval EFI_INVALID_PARAMETER Invalid parameter.
@retval EFI_NOT_FOUND No EndTag found.
**/
EFI_STATUS
EFIAPI
AmlSetRdListCheckSum (
IN AML_OBJECT_NODE * BufferOpNode,
IN UINT8 CheckSum
);
#endif // AML_UTILITY_H_