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Commit bbc24134 authored by Lin Ming's avatar Lin Ming Committed by Len Brown
Browse files

ACPICA: Add function to dereference returned reference objects 

Examines the return object from a call to acpi_evaluate_object.
Any Index or RefOf references are automatically dereferenced in
an attempt to return something useful (these reference types
cannot be converted into an external ACPI_OBJECT.)
Lin Ming, Bob Moore.

http://bugzilla.kernel.org/show_bug.cgi?id=11105



Signed-off-by: default avatarLin Ming <ming.m.lin@intel.com>
Signed-off-by: default avatarBob Moore <robert.moore@intel.com>
Signed-off-by: default avatarAndi Kleen <ak@linux.intel.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent b417d40b

drivers/acpi/namespace/nsxfeval.c

+79 −0
Original line number Diff line number Diff line
@@ -45,9 +45,14 @@ 
#include <acpi/acpi.h>

#include <acpi/acnamesp.h>

#include <acpi/acinterp.h>

#include <acpi/amlcode.h>



#define _COMPONENT          ACPI_NAMESPACE

ACPI_MODULE_NAME("nsxfeval")



/* Local prototypes */

static void acpi_ns_resolve_references(struct acpi_evaluate_info *info);



#ifdef ACPI_FUTURE_USAGE

/*******************************************************************************

 *
@@ -69,6 +74,7 @@ ACPI_MODULE_NAME("nsxfeval") 
 *              be valid (non-null)

 *

 ******************************************************************************/



acpi_status

acpi_evaluate_object_typed(acpi_handle handle,

			   acpi_string pathname,
@@ -283,6 +289,10 @@ acpi_evaluate_object(acpi_handle handle, 


			if (ACPI_SUCCESS(status)) {



				/* Dereference Index and ref_of references */



				acpi_ns_resolve_references(info);



				/* Get the size of the returned object */



				status =
@@ -350,6 +360,74 @@ acpi_evaluate_object(acpi_handle handle, 


ACPI_EXPORT_SYMBOL(acpi_evaluate_object)



/*******************************************************************************

 *

 * FUNCTION:    acpi_ns_resolve_references

 *

 * PARAMETERS:  Info                    - Evaluation info block

 *

 * RETURN:      Info->return_object is replaced with the dereferenced object

 *

 * DESCRIPTION: Dereference certain reference objects. Called before an

 *              internal return object is converted to an external union acpi_object.

 *

 * Performs an automatic dereference of Index and ref_of reference objects.

 * These reference objects are not supported by the union acpi_object, so this is a

 * last resort effort to return something useful. Also, provides compatibility

 * with other ACPI implementations.

 *

 * NOTE: does not handle references within returned package objects or nested

 * references, but this support could be added later if found to be necessary.

 *

 ******************************************************************************/

static void acpi_ns_resolve_references(struct acpi_evaluate_info *info)

{

	union acpi_operand_object *obj_desc = NULL;

	struct acpi_namespace_node *node;



	/* We are interested in reference objects only */



	if (ACPI_GET_OBJECT_TYPE(info->return_object) !=

	    ACPI_TYPE_LOCAL_REFERENCE) {

		return;

	}



	/*

	 * Two types of references are supported - those created by Index and

	 * ref_of operators. A name reference (AML_NAMEPATH_OP) can be converted

	 * to an union acpi_object, so it is not dereferenced here. A ddb_handle

	 * (AML_LOAD_OP) cannot be dereferenced, nor can it be converted to

	 * an union acpi_object.

	 */

	switch (info->return_object->reference.opcode) {

	case AML_INDEX_OP:



		obj_desc = *(info->return_object->reference.where);

		break;



	case AML_REF_OF_OP:



		node = info->return_object->reference.object;

		if (node) {

			obj_desc = node->object;

		}

		break;



	default:

		return;

	}



	/* Replace the existing reference object */



	if (obj_desc) {

		acpi_ut_add_reference(obj_desc);

		acpi_ut_remove_reference(info->return_object);

		info->return_object = obj_desc;

	}



	return;

}



/*******************************************************************************

 *

 * FUNCTION:    acpi_walk_namespace
@@ -379,6 +457,7 @@ ACPI_EXPORT_SYMBOL(acpi_evaluate_object) 
 *              function, etc.

 *

 ******************************************************************************/



acpi_status

acpi_walk_namespace(acpi_object_type type,

		    acpi_handle start_object,