drivers/acpi/acpica/exresolv.c - linux - Git at Google

 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
 /******************************************************************************
  *
  * Module Name: exresolv - AML Interpreter object resolution
  *
  * Copyright (C) 2000 - 2023, Intel Corp.
  *
  *****************************************************************************/

 #include <acpi/acpi.h>
 #include "accommon.h"
 #include "amlcode.h"
 #include "acdispat.h"
 #include "acinterp.h"
 #include "acnamesp.h"

 #define _COMPONENT          ACPI_EXECUTER
 ACPI_MODULE_NAME("exresolv")

 /* Local prototypes */
 static acpi_status
 acpi_ex_resolve_object_to_value(union acpi_operand_object **stack_ptr,
 				struct acpi_walk_state *walk_state);

 /*******************************************************************************
  *
  * FUNCTION:    acpi_ex_resolve_to_value
  *
  * PARAMETERS:  **stack_ptr         - Points to entry on obj_stack, which can
  *                                    be either an (union acpi_operand_object *)
  *                                    or an acpi_handle.
  *              walk_state          - Current method state
  *
  * RETURN:      Status
  *
  * DESCRIPTION: Convert Reference objects to values
  *
  ******************************************************************************/

 acpi_status
 acpi_ex_resolve_to_value(union acpi_operand_object **stack_ptr,
 			 struct acpi_walk_state *walk_state)
 {
 	acpi_status status;

 	ACPI_FUNCTION_TRACE_PTR(ex_resolve_to_value, stack_ptr);

 	if (!stack_ptr || !*stack_ptr) {
 		ACPI_ERROR((AE_INFO, "Internal - null pointer"));
 		return_ACPI_STATUS(AE_AML_NO_OPERAND);
 	}

 	/*
 	 * The entity pointed to by the stack_ptr can be either
 	 * 1) A valid union acpi_operand_object, or
 	 * 2) A struct acpi_namespace_node (named_obj)
 	 */
 	if (ACPI_GET_DESCRIPTOR_TYPE(*stack_ptr) == ACPI_DESC_TYPE_OPERAND) {
 		status = acpi_ex_resolve_object_to_value(stack_ptr, walk_state);
 		if (ACPI_FAILURE(status)) {
 			return_ACPI_STATUS(status);
 		}

 		if (!*stack_ptr) {
 			ACPI_ERROR((AE_INFO, "Internal - null pointer"));
 			return_ACPI_STATUS(AE_AML_NO_OPERAND);
 		}
 	}

 	/*
 	 * Object on the stack may have changed if acpi_ex_resolve_object_to_value()
 	 * was called (i.e., we can't use an _else_ here.)
 	 */
 	if (ACPI_GET_DESCRIPTOR_TYPE(*stack_ptr) == ACPI_DESC_TYPE_NAMED) {
 		status =
 		    acpi_ex_resolve_node_to_value(ACPI_CAST_INDIRECT_PTR
 						  (struct acpi_namespace_node,
 						   stack_ptr), walk_state);
 		if (ACPI_FAILURE(status)) {
 			return_ACPI_STATUS(status);
 		}
 	}

 	ACPI_DEBUG_PRINT((ACPI_DB_EXEC, "Resolved object %p\n", *stack_ptr));
 	return_ACPI_STATUS(AE_OK);
 }

 /*******************************************************************************
  *
  * FUNCTION:    acpi_ex_resolve_object_to_value
  *
  * PARAMETERS:  stack_ptr       - Pointer to an internal object
  *              walk_state      - Current method state
  *
  * RETURN:      Status
  *
  * DESCRIPTION: Retrieve the value from an internal object. The Reference type
  *              uses the associated AML opcode to determine the value.
  *
  ******************************************************************************/

 static acpi_status
 acpi_ex_resolve_object_to_value(union acpi_operand_object **stack_ptr,
 				struct acpi_walk_state *walk_state)
 {
 	acpi_status status = AE_OK;
 	union acpi_operand_object *stack_desc;
 	union acpi_operand_object *obj_desc = NULL;
 	u8 ref_type;

 	ACPI_FUNCTION_TRACE(ex_resolve_object_to_value);

 	stack_desc = *stack_ptr;

 	/* This is an object of type union acpi_operand_object */

 	switch (stack_desc->common.type) {
 	case ACPI_TYPE_LOCAL_REFERENCE:

 		ref_type = stack_desc->reference.class;

 		switch (ref_type) {
 		case ACPI_REFCLASS_LOCAL:
 		case ACPI_REFCLASS_ARG:
 			/*
 			 * Get the local from the method's state info
 			 * Note: this increments the local's object reference count
 			 */
 			status = acpi_ds_method_data_get_value(ref_type,
 							       stack_desc->
 							       reference.value,
 							       walk_state,
 							       &obj_desc);
 			if (ACPI_FAILURE(status)) {
 				return_ACPI_STATUS(status);
 			}

 			ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
 					  "[Arg/Local %X] ValueObj is %p\n",
 					  stack_desc->reference.value,
 					  obj_desc));

 			/*
 			 * Now we can delete the original Reference Object and
 			 * replace it with the resolved value
 			 */
 			acpi_ut_remove_reference(stack_desc);
 			*stack_ptr = obj_desc;
 			break;

 		case ACPI_REFCLASS_INDEX:

 			switch (stack_desc->reference.target_type) {
 			case ACPI_TYPE_BUFFER_FIELD:

 				/* Just return - do not dereference */
 				break;

 			case ACPI_TYPE_PACKAGE:

 				/* If method call or copy_object - do not dereference */

 				if ((walk_state->opcode ==
 				     AML_INT_METHODCALL_OP)
 				    || (walk_state->opcode ==
 					AML_COPY_OBJECT_OP)) {
 					break;
 				}

 				/* Otherwise, dereference the package_index to a package element */

 				obj_desc = *stack_desc->reference.where;
 				if (obj_desc) {
 					/*
 					 * Valid object descriptor, copy pointer to return value
 					 * (i.e., dereference the package index)
 					 * Delete the ref object, increment the returned object
 					 */
 					acpi_ut_add_reference(obj_desc);
 					*stack_ptr = obj_desc;
 				} else {
 					/*
 					 * A NULL object descriptor means an uninitialized element of
 					 * the package, can't dereference it
 					 */
 					ACPI_ERROR((AE_INFO,
 						    "Attempt to dereference an Index to "
 						    "NULL package element Idx=%p",
 						    stack_desc));
 					status = AE_AML_UNINITIALIZED_ELEMENT;
 				}
 				break;

 			default:

 				/* Invalid reference object */

 				ACPI_ERROR((AE_INFO,
 					    "Unknown TargetType 0x%X in Index/Reference object %p",
 					    stack_desc->reference.target_type,
 					    stack_desc));
 				status = AE_AML_INTERNAL;
 				break;
 			}
 			break;

 		case ACPI_REFCLASS_REFOF:
 		case ACPI_REFCLASS_DEBUG:
 		case ACPI_REFCLASS_TABLE:

 			/* Just leave the object as-is, do not dereference */

 			break;

 		case ACPI_REFCLASS_NAME:	/* Reference to a named object */

 			/* Dereference the name */

 			if ((stack_desc->reference.node->type ==
 			     ACPI_TYPE_DEVICE)
 			    || (stack_desc->reference.node->type ==
 				ACPI_TYPE_THERMAL)) {

 				/* These node types do not have 'real' subobjects */

 				*stack_ptr = (void *)stack_desc->reference.node;
 			} else {
 				/* Get the object pointed to by the namespace node */

 				*stack_ptr =
 				    (stack_desc->reference.node)->object;
 				acpi_ut_add_reference(*stack_ptr);
 			}

 			acpi_ut_remove_reference(stack_desc);
 			break;

 		default:

 			ACPI_ERROR((AE_INFO,
 				    "Unknown Reference type 0x%X in %p",
 				    ref_type, stack_desc));
 			status = AE_AML_INTERNAL;
 			break;
 		}
 		break;

 	case ACPI_TYPE_BUFFER:

 		status = acpi_ds_get_buffer_arguments(stack_desc);
 		break;

 	case ACPI_TYPE_PACKAGE:

 		status = acpi_ds_get_package_arguments(stack_desc);
 		break;

 	case ACPI_TYPE_BUFFER_FIELD:
 	case ACPI_TYPE_LOCAL_REGION_FIELD:
 	case ACPI_TYPE_LOCAL_BANK_FIELD:
 	case ACPI_TYPE_LOCAL_INDEX_FIELD:

 		ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
 				  "FieldRead SourceDesc=%p Type=%X\n",
 				  stack_desc, stack_desc->common.type));

 		status =
 		    acpi_ex_read_data_from_field(walk_state, stack_desc,
 						 &obj_desc);

 		/* Remove a reference to the original operand, then override */

 		acpi_ut_remove_reference(*stack_ptr);
 		*stack_ptr = (void *)obj_desc;
 		break;

 	default:

 		break;
 	}

 	return_ACPI_STATUS(status);
 }

 /*******************************************************************************
  *
  * FUNCTION:    acpi_ex_resolve_multiple
  *
  * PARAMETERS:  walk_state          - Current state (contains AML opcode)
  *              operand             - Starting point for resolution
  *              return_type         - Where the object type is returned
  *              return_desc         - Where the resolved object is returned
  *
  * RETURN:      Status
  *
  * DESCRIPTION: Return the base object and type. Traverse a reference list if
  *              necessary to get to the base object.
  *
  ******************************************************************************/

 acpi_status
 acpi_ex_resolve_multiple(struct acpi_walk_state *walk_state,
 			 union acpi_operand_object *operand,
 			 acpi_object_type *return_type,
 			 union acpi_operand_object **return_desc)
 {
 	union acpi_operand_object *obj_desc = ACPI_CAST_PTR(void, operand);
 	struct acpi_namespace_node *node =
 	    ACPI_CAST_PTR(struct acpi_namespace_node, operand);
 	acpi_object_type type;
 	acpi_status status;

 	ACPI_FUNCTION_TRACE(acpi_ex_resolve_multiple);

 	/* Operand can be either a namespace node or an operand descriptor */

 	switch (ACPI_GET_DESCRIPTOR_TYPE(obj_desc)) {
 	case ACPI_DESC_TYPE_OPERAND:

 		type = obj_desc->common.type;
 		break;

 	case ACPI_DESC_TYPE_NAMED:

 		type = ((struct acpi_namespace_node *)obj_desc)->type;
 		obj_desc = acpi_ns_get_attached_object(node);

 		/* If we had an Alias node, use the attached object for type info */

 		if (type == ACPI_TYPE_LOCAL_ALIAS) {
 			type = ((struct acpi_namespace_node *)obj_desc)->type;
 			obj_desc = acpi_ns_get_attached_object((struct
 								acpi_namespace_node
 								*)obj_desc);
 		}

 		switch (type) {
 		case ACPI_TYPE_DEVICE:
 		case ACPI_TYPE_THERMAL:

 			/* These types have no attached subobject */
 			break;

 		default:

 			/* All other types require a subobject */

 			if (!obj_desc) {
 				ACPI_ERROR((AE_INFO,
 					    "[%4.4s] Node is unresolved or uninitialized",
 					    acpi_ut_get_node_name(node)));
 				return_ACPI_STATUS(AE_AML_UNINITIALIZED_NODE);
 			}
 			break;
 		}
 		break;

 	default:
 		return_ACPI_STATUS(AE_AML_OPERAND_TYPE);
 	}

 	/* If type is anything other than a reference, we are done */

 	if (type != ACPI_TYPE_LOCAL_REFERENCE) {
 		goto exit;
 	}

 	/*
 	 * For reference objects created via the ref_of, Index, or Load/load_table
 	 * operators, we need to get to the base object (as per the ACPI
 	 * specification of the object_type and size_of operators). This means
 	 * traversing the list of possibly many nested references.
 	 */
 	while (obj_desc->common.type == ACPI_TYPE_LOCAL_REFERENCE) {
 		switch (obj_desc->reference.class) {
 		case ACPI_REFCLASS_REFOF:
 		case ACPI_REFCLASS_NAME:

 			/* Dereference the reference pointer */

 			if (obj_desc->reference.class == ACPI_REFCLASS_REFOF) {
 				node = obj_desc->reference.object;
 			} else {	/* AML_INT_NAMEPATH_OP */

 				node = obj_desc->reference.node;
 			}

 			/* All "References" point to a NS node */

 			if (ACPI_GET_DESCRIPTOR_TYPE(node) !=
 			    ACPI_DESC_TYPE_NAMED) {
 				ACPI_ERROR((AE_INFO,
 					    "Not a namespace node %p [%s]",
 					    node,
 					    acpi_ut_get_descriptor_name(node)));
 				return_ACPI_STATUS(AE_AML_INTERNAL);
 			}

 			/* Get the attached object */

 			obj_desc = acpi_ns_get_attached_object(node);
 			if (!obj_desc) {

 				/* No object, use the NS node type */

 				type = acpi_ns_get_type(node);
 				goto exit;
 			}

 			/* Check for circular references */

 			if (obj_desc == operand) {
 				return_ACPI_STATUS(AE_AML_CIRCULAR_REFERENCE);
 			}
 			break;

 		case ACPI_REFCLASS_INDEX:

 			/* Get the type of this reference (index into another object) */

 			type = obj_desc->reference.target_type;
 			if (type != ACPI_TYPE_PACKAGE) {
 				goto exit;
 			}

 			/*
 			 * The main object is a package, we want to get the type
 			 * of the individual package element that is referenced by
 			 * the index.
 			 *
 			 * This could of course in turn be another reference object.
 			 */
 			obj_desc = *(obj_desc->reference.where);
 			if (!obj_desc) {

 				/* NULL package elements are allowed */

 				type = 0;	/* Uninitialized */
 				goto exit;
 			}
 			break;

 		case ACPI_REFCLASS_TABLE:

 			type = ACPI_TYPE_DDB_HANDLE;
 			goto exit;

 		case ACPI_REFCLASS_LOCAL:
 		case ACPI_REFCLASS_ARG:

 			if (return_desc) {
 				status =
 				    acpi_ds_method_data_get_value(obj_desc->
 								  reference.
 								  class,
 								  obj_desc->
 								  reference.
 								  value,
 								  walk_state,
 								  &obj_desc);
 				if (ACPI_FAILURE(status)) {
 					return_ACPI_STATUS(status);
 				}
 				acpi_ut_remove_reference(obj_desc);
 			} else {
 				status =
 				    acpi_ds_method_data_get_node(obj_desc->
 								 reference.
 								 class,
 								 obj_desc->
 								 reference.
 								 value,
 								 walk_state,
 								 &node);
 				if (ACPI_FAILURE(status)) {
 					return_ACPI_STATUS(status);
 				}

 				obj_desc = acpi_ns_get_attached_object(node);
 				if (!obj_desc) {
 					type = ACPI_TYPE_ANY;
 					goto exit;
 				}
 			}
 			break;

 		case ACPI_REFCLASS_DEBUG:

 			/* The Debug Object is of type "DebugObject" */

 			type = ACPI_TYPE_DEBUG_OBJECT;
 			goto exit;

 		default:

 			ACPI_ERROR((AE_INFO,
 				    "Unknown Reference Class 0x%2.2X",
 				    obj_desc->reference.class));
 			return_ACPI_STATUS(AE_AML_INTERNAL);
 		}
 	}

 	/*
 	 * Now we are guaranteed to have an object that has not been created
 	 * via the ref_of or Index operators.
 	 */
 	type = obj_desc->common.type;

 exit:
 	/* Convert internal types to external types */

 	switch (type) {
 	case ACPI_TYPE_LOCAL_REGION_FIELD:
 	case ACPI_TYPE_LOCAL_BANK_FIELD:
 	case ACPI_TYPE_LOCAL_INDEX_FIELD:

 		type = ACPI_TYPE_FIELD_UNIT;
 		break;

 	case ACPI_TYPE_LOCAL_SCOPE:

 		/* Per ACPI Specification, Scope is untyped */

 		type = ACPI_TYPE_ANY;
 		break;

 	default:

 		/* No change to Type required */

 		break;
 	}

 	*return_type = type;
 	if (return_desc) {
 		*return_desc = obj_desc;
 	}
 	return_ACPI_STATUS(AE_OK);
 }
	// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
	/******************************************************************************
	*
	* Module Name: exresolv - AML Interpreter object resolution
	*
	* Copyright (C) 2000 - 2023, Intel Corp.
	*
	*****************************************************************************/

	#include <acpi/acpi.h>
	#include "accommon.h"
	#include "amlcode.h"
	#include "acdispat.h"
	#include "acinterp.h"
	#include "acnamesp.h"

	#define _COMPONENT ACPI_EXECUTER
	ACPI_MODULE_NAME("exresolv")

	/* Local prototypes */
	static acpi_status
	acpi_ex_resolve_object_to_value(union acpi_operand_object **stack_ptr,
	struct acpi_walk_state *walk_state);

	/*******************************************************************************
	*
	* FUNCTION: acpi_ex_resolve_to_value
	*
	* PARAMETERS: **stack_ptr - Points to entry on obj_stack, which can
	* be either an (union acpi_operand_object *)
	* or an acpi_handle.
	* walk_state - Current method state
	*
	* RETURN: Status
	*
	* DESCRIPTION: Convert Reference objects to values
	*
	******************************************************************************/

	acpi_status
	acpi_ex_resolve_to_value(union acpi_operand_object **stack_ptr,
	struct acpi_walk_state *walk_state)
	{
	acpi_status status;

	ACPI_FUNCTION_TRACE_PTR(ex_resolve_to_value, stack_ptr);

	if (!stack_ptr \|\| !*stack_ptr) {
	ACPI_ERROR((AE_INFO, "Internal - null pointer"));
	return_ACPI_STATUS(AE_AML_NO_OPERAND);
	}

	/*
	* The entity pointed to by the stack_ptr can be either
	* 1) A valid union acpi_operand_object, or
	* 2) A struct acpi_namespace_node (named_obj)
	*/
	if (ACPI_GET_DESCRIPTOR_TYPE(*stack_ptr) == ACPI_DESC_TYPE_OPERAND) {
	status = acpi_ex_resolve_object_to_value(stack_ptr, walk_state);
	if (ACPI_FAILURE(status)) {
	return_ACPI_STATUS(status);
	}

	if (!*stack_ptr) {
	ACPI_ERROR((AE_INFO, "Internal - null pointer"));
	return_ACPI_STATUS(AE_AML_NO_OPERAND);
	}
	}

	/*
	* Object on the stack may have changed if acpi_ex_resolve_object_to_value()
	* was called (i.e., we can't use an _else_ here.)
	*/
	if (ACPI_GET_DESCRIPTOR_TYPE(*stack_ptr) == ACPI_DESC_TYPE_NAMED) {
	status =
	acpi_ex_resolve_node_to_value(ACPI_CAST_INDIRECT_PTR
	(struct acpi_namespace_node,
	stack_ptr), walk_state);
	if (ACPI_FAILURE(status)) {
	return_ACPI_STATUS(status);
	}
	}

	ACPI_DEBUG_PRINT((ACPI_DB_EXEC, "Resolved object %p\n", *stack_ptr));
	return_ACPI_STATUS(AE_OK);
	}

	/*******************************************************************************
	*
	* FUNCTION: acpi_ex_resolve_object_to_value
	*
	* PARAMETERS: stack_ptr - Pointer to an internal object
	* walk_state - Current method state
	*
	* RETURN: Status
	*
	* DESCRIPTION: Retrieve the value from an internal object. The Reference type
	* uses the associated AML opcode to determine the value.
	*
	******************************************************************************/

	static acpi_status
	acpi_ex_resolve_object_to_value(union acpi_operand_object **stack_ptr,
	struct acpi_walk_state *walk_state)
	{
	acpi_status status = AE_OK;
	union acpi_operand_object *stack_desc;
	union acpi_operand_object *obj_desc = NULL;
	u8 ref_type;

	ACPI_FUNCTION_TRACE(ex_resolve_object_to_value);

	stack_desc = *stack_ptr;

	/* This is an object of type union acpi_operand_object */

	switch (stack_desc->common.type) {
	case ACPI_TYPE_LOCAL_REFERENCE:

	ref_type = stack_desc->reference.class;

	switch (ref_type) {
	case ACPI_REFCLASS_LOCAL:
	case ACPI_REFCLASS_ARG:
	/*
	* Get the local from the method's state info
	* Note: this increments the local's object reference count
	*/
	status = acpi_ds_method_data_get_value(ref_type,
	stack_desc->
	reference.value,
	walk_state,
	&obj_desc);
	if (ACPI_FAILURE(status)) {
	return_ACPI_STATUS(status);
	}

	ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
	"[Arg/Local %X] ValueObj is %p\n",
	stack_desc->reference.value,
	obj_desc));

	/*
	* Now we can delete the original Reference Object and
	* replace it with the resolved value
	*/
	acpi_ut_remove_reference(stack_desc);
	*stack_ptr = obj_desc;
	break;

	case ACPI_REFCLASS_INDEX:

	switch (stack_desc->reference.target_type) {
	case ACPI_TYPE_BUFFER_FIELD:

	/* Just return - do not dereference */
	break;

	case ACPI_TYPE_PACKAGE:

	/* If method call or copy_object - do not dereference */

	if ((walk_state->opcode ==
	AML_INT_METHODCALL_OP)
	\|\| (walk_state->opcode ==
	AML_COPY_OBJECT_OP)) {
	break;
	}

	/* Otherwise, dereference the package_index to a package element */

	obj_desc = *stack_desc->reference.where;
	if (obj_desc) {
	/*
	* Valid object descriptor, copy pointer to return value
	* (i.e., dereference the package index)
	* Delete the ref object, increment the returned object
	*/
	acpi_ut_add_reference(obj_desc);
	*stack_ptr = obj_desc;
	} else {
	/*
	* A NULL object descriptor means an uninitialized element of
	* the package, can't dereference it
	*/
	ACPI_ERROR((AE_INFO,
	"Attempt to dereference an Index to "
	"NULL package element Idx=%p",
	stack_desc));
	status = AE_AML_UNINITIALIZED_ELEMENT;
	}
	break;

	default:

	/* Invalid reference object */

	ACPI_ERROR((AE_INFO,
	"Unknown TargetType 0x%X in Index/Reference object %p",
	stack_desc->reference.target_type,
	stack_desc));
	status = AE_AML_INTERNAL;
	break;
	}
	break;

	case ACPI_REFCLASS_REFOF:
	case ACPI_REFCLASS_DEBUG:
	case ACPI_REFCLASS_TABLE:

	/* Just leave the object as-is, do not dereference */

	break;

	case ACPI_REFCLASS_NAME: /* Reference to a named object */

	/* Dereference the name */

	if ((stack_desc->reference.node->type ==
	ACPI_TYPE_DEVICE)
	\|\| (stack_desc->reference.node->type ==
	ACPI_TYPE_THERMAL)) {

	/* These node types do not have 'real' subobjects */

	stack_ptr = (void )stack_desc->reference.node;
	} else {
	/* Get the object pointed to by the namespace node */

	*stack_ptr =
	(stack_desc->reference.node)->object;
	acpi_ut_add_reference(*stack_ptr);
	}

	acpi_ut_remove_reference(stack_desc);
	break;

	default:

	ACPI_ERROR((AE_INFO,
	"Unknown Reference type 0x%X in %p",
	ref_type, stack_desc));
	status = AE_AML_INTERNAL;
	break;
	}
	break;

	case ACPI_TYPE_BUFFER:

	status = acpi_ds_get_buffer_arguments(stack_desc);
	break;

	case ACPI_TYPE_PACKAGE:

	status = acpi_ds_get_package_arguments(stack_desc);
	break;

	case ACPI_TYPE_BUFFER_FIELD:
	case ACPI_TYPE_LOCAL_REGION_FIELD:
	case ACPI_TYPE_LOCAL_BANK_FIELD:
	case ACPI_TYPE_LOCAL_INDEX_FIELD:

	ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
	"FieldRead SourceDesc=%p Type=%X\n",
	stack_desc, stack_desc->common.type));

	status =
	acpi_ex_read_data_from_field(walk_state, stack_desc,
	&obj_desc);

	/* Remove a reference to the original operand, then override */

	acpi_ut_remove_reference(*stack_ptr);
	stack_ptr = (void )obj_desc;
	break;

	default:

	break;
	}

	return_ACPI_STATUS(status);
	}

	/*******************************************************************************
	*
	* FUNCTION: acpi_ex_resolve_multiple
	*
	* PARAMETERS: walk_state - Current state (contains AML opcode)
	* operand - Starting point for resolution
	* return_type - Where the object type is returned
	* return_desc - Where the resolved object is returned
	*
	* RETURN: Status
	*
	* DESCRIPTION: Return the base object and type. Traverse a reference list if
	* necessary to get to the base object.
	*
	******************************************************************************/

	acpi_status
	acpi_ex_resolve_multiple(struct acpi_walk_state *walk_state,
	union acpi_operand_object *operand,
	acpi_object_type *return_type,
	union acpi_operand_object **return_desc)
	{
	union acpi_operand_object *obj_desc = ACPI_CAST_PTR(void, operand);
	struct acpi_namespace_node *node =
	ACPI_CAST_PTR(struct acpi_namespace_node, operand);
	acpi_object_type type;
	acpi_status status;

	ACPI_FUNCTION_TRACE(acpi_ex_resolve_multiple);

	/* Operand can be either a namespace node or an operand descriptor */

	switch (ACPI_GET_DESCRIPTOR_TYPE(obj_desc)) {
	case ACPI_DESC_TYPE_OPERAND:

	type = obj_desc->common.type;
	break;

	case ACPI_DESC_TYPE_NAMED:

	type = ((struct acpi_namespace_node *)obj_desc)->type;
	obj_desc = acpi_ns_get_attached_object(node);

	/* If we had an Alias node, use the attached object for type info */

	if (type == ACPI_TYPE_LOCAL_ALIAS) {
	type = ((struct acpi_namespace_node *)obj_desc)->type;
	obj_desc = acpi_ns_get_attached_object((struct
	acpi_namespace_node
	*)obj_desc);
	}

	switch (type) {
	case ACPI_TYPE_DEVICE:
	case ACPI_TYPE_THERMAL:

	/* These types have no attached subobject */
	break;

	default:

	/* All other types require a subobject */

	if (!obj_desc) {
	ACPI_ERROR((AE_INFO,
	"[%4.4s] Node is unresolved or uninitialized",
	acpi_ut_get_node_name(node)));
	return_ACPI_STATUS(AE_AML_UNINITIALIZED_NODE);
	}
	break;
	}
	break;

	default:
	return_ACPI_STATUS(AE_AML_OPERAND_TYPE);
	}

	/* If type is anything other than a reference, we are done */

	if (type != ACPI_TYPE_LOCAL_REFERENCE) {
	goto exit;
	}

	/*
	* For reference objects created via the ref_of, Index, or Load/load_table
	* operators, we need to get to the base object (as per the ACPI
	* specification of the object_type and size_of operators). This means
	* traversing the list of possibly many nested references.
	*/
	while (obj_desc->common.type == ACPI_TYPE_LOCAL_REFERENCE) {
	switch (obj_desc->reference.class) {
	case ACPI_REFCLASS_REFOF:
	case ACPI_REFCLASS_NAME:

	/* Dereference the reference pointer */

	if (obj_desc->reference.class == ACPI_REFCLASS_REFOF) {
	node = obj_desc->reference.object;
	} else { /* AML_INT_NAMEPATH_OP */

	node = obj_desc->reference.node;
	}

	/* All "References" point to a NS node */

	if (ACPI_GET_DESCRIPTOR_TYPE(node) !=
	ACPI_DESC_TYPE_NAMED) {
	ACPI_ERROR((AE_INFO,
	"Not a namespace node %p [%s]",
	node,
	acpi_ut_get_descriptor_name(node)));
	return_ACPI_STATUS(AE_AML_INTERNAL);
	}

	/* Get the attached object */

	obj_desc = acpi_ns_get_attached_object(node);
	if (!obj_desc) {

	/* No object, use the NS node type */

	type = acpi_ns_get_type(node);
	goto exit;
	}

	/* Check for circular references */

	if (obj_desc == operand) {
	return_ACPI_STATUS(AE_AML_CIRCULAR_REFERENCE);
	}
	break;

	case ACPI_REFCLASS_INDEX:

	/* Get the type of this reference (index into another object) */

	type = obj_desc->reference.target_type;
	if (type != ACPI_TYPE_PACKAGE) {
	goto exit;
	}

	/*
	* The main object is a package, we want to get the type
	* of the individual package element that is referenced by
	* the index.
	*
	* This could of course in turn be another reference object.
	*/
	obj_desc = *(obj_desc->reference.where);
	if (!obj_desc) {

	/* NULL package elements are allowed */

	type = 0; /* Uninitialized */
	goto exit;
	}
	break;

	case ACPI_REFCLASS_TABLE:

	type = ACPI_TYPE_DDB_HANDLE;
	goto exit;

	case ACPI_REFCLASS_LOCAL:
	case ACPI_REFCLASS_ARG:

	if (return_desc) {
	status =
	acpi_ds_method_data_get_value(obj_desc->
	reference.
	class,
	obj_desc->
	reference.
	value,
	walk_state,
	&obj_desc);
	if (ACPI_FAILURE(status)) {
	return_ACPI_STATUS(status);
	}
	acpi_ut_remove_reference(obj_desc);
	} else {
	status =
	acpi_ds_method_data_get_node(obj_desc->
	reference.
	class,
	obj_desc->
	reference.
	value,
	walk_state,
	&node);
	if (ACPI_FAILURE(status)) {
	return_ACPI_STATUS(status);
	}

	obj_desc = acpi_ns_get_attached_object(node);
	if (!obj_desc) {
	type = ACPI_TYPE_ANY;
	goto exit;
	}
	}
	break;

	case ACPI_REFCLASS_DEBUG:

	/* The Debug Object is of type "DebugObject" */

	type = ACPI_TYPE_DEBUG_OBJECT;
	goto exit;

	default:

	ACPI_ERROR((AE_INFO,
	"Unknown Reference Class 0x%2.2X",
	obj_desc->reference.class));
	return_ACPI_STATUS(AE_AML_INTERNAL);
	}
	}

	/*
	* Now we are guaranteed to have an object that has not been created
	* via the ref_of or Index operators.
	*/
	type = obj_desc->common.type;

	exit:
	/* Convert internal types to external types */

	switch (type) {
	case ACPI_TYPE_LOCAL_REGION_FIELD:
	case ACPI_TYPE_LOCAL_BANK_FIELD:
	case ACPI_TYPE_LOCAL_INDEX_FIELD:

	type = ACPI_TYPE_FIELD_UNIT;
	break;

	case ACPI_TYPE_LOCAL_SCOPE:

	/* Per ACPI Specification, Scope is untyped */

	type = ACPI_TYPE_ANY;
	break;

	default:

	/* No change to Type required */

	break;
	}

	*return_type = type;
	if (return_desc) {
	*return_desc = obj_desc;
	}
	return_ACPI_STATUS(AE_OK);
	}