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

["Sami Mujawar" <sami.mujawar@arm.com>]

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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