/******************************************************************************
 *
 * Module Name: nspredef - Validation of ACPI predefined methods and objects
 *              $Revision: 1.1 $
 *
 *****************************************************************************/

/*
 * Copyright (C) 2000 - 2008, Intel Corp.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    substantially similar to the "NO WARRANTY" disclaimer below
 *    ("Disclaimer") and any redistribution must be conditioned upon
 *    including a substantially similar Disclaimer requirement for further
 *    binary redistribution.
 * 3. Neither the names of the above-listed copyright holders nor the names
 *    of any contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * NO WARRANTY
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 */

#include <acpi/acpi.h>
#include <acpi/acnamesp.h>
#include <acpi/acpredef.h>

#define _COMPONENT          ACPI_NAMESPACE
ACPI_MODULE_NAME("nspredef")

/*******************************************************************************
 *
 * This module validates predefined ACPI objects that appear in the namespace,
 * at the time they are evaluated (via acpi_evaluate_object). The purpose of this
 * validation is to detect problems with BIOS-exposed predefined ACPI objects
 * before the results are returned to the ACPI-related drivers.
 *
 * There are several areas that are validated:
 *
 *  1) The number of input arguments as defined by the method/object in the
 *      ASL is validated against the ACPI specification.
 *  2) The type of the return object (if any) is validated against the ACPI
 *      specification.
 *  3) For returned package objects, the count of package elements is
 *      validated, as well as the type of each package element. Nested
 *      packages are supported.
 *
 * For any problems found, a warning message is issued.
 *
 ******************************************************************************/
/* Local prototypes */
static acpi_status
acpi_ns_check_package(char *pathname,
                      union acpi_operand_object *return_object,
                      const union acpi_predefined_info *predefined);

static acpi_status
acpi_ns_check_package_elements(char *pathname,
                               union acpi_operand_object **elements,
                               u8 type1, u32 count1, u8 type2, u32 count2);

static acpi_status
acpi_ns_check_object_type(char *pathname,
                          union acpi_operand_object *return_object,
                          u32 expected_btypes, u32 package_index);

static acpi_status
acpi_ns_check_reference(char *pathname,
                        union acpi_operand_object *return_object);

/*
 * Names for the types that can be returned by the predefined objects.
 * Used for warning messages. Must be in the same order as the ACPI_RTYPEs
 */
static const char *acpi_rtype_names[] = {
        "/Integer",
        "/String",
        "/Buffer",
        "/Package",
        "/Reference",
};

#define ACPI_NOT_PACKAGE    ACPI_UINT32_MAX

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_check_predefined_names
 *
 * PARAMETERS:  Node            - Namespace node for the method/object
 *              return_object   - Object returned from the evaluation of this
 *                                method/object
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Check an ACPI name for a match in the predefined name list.
 *
 ******************************************************************************/

acpi_status
acpi_ns_check_predefined_names(struct acpi_namespace_node *node,
                               union acpi_operand_object *return_object)
{
        acpi_status status = AE_OK;
        const union acpi_predefined_info *predefined;
        char *pathname;

        /* Match the name for this method/object against the predefined list */

        predefined = acpi_ns_check_for_predefined_name(node);
        if (!predefined) {

                /* Name was not one of the predefined names */

                return (AE_OK);
        }

        /* Get the full pathname to the object, for use in error messages */

        pathname = acpi_ns_get_external_pathname(node);
        if (!pathname) {
                pathname = ACPI_CAST_PTR(char, predefined->info.name);
        }

        /*
         * Check that the parameter count for this method is in accordance
         * with the ACPI specification.
         */
        acpi_ns_check_parameter_count(pathname, node, predefined);

        /*
         * If there is no return value, check if we require a return value for
         * this predefined name. Either one return value is expected, or none,
         * for both methods and other objects.
         *
         * Exit now if there is no return object. Warning if one was expected.
         */
        if (!return_object) {
                if ((predefined->info.expected_btypes) &&
                    (!(predefined->info.expected_btypes & ACPI_RTYPE_NONE))) {
                        ACPI_ERROR((AE_INFO,
                                    "%s: Missing expected return value",
                                    pathname));

                        status = AE_AML_NO_RETURN_VALUE;
                }
                goto exit;
        }

        /*
         * We have a return value, but if one wasn't expected, just exit, this is
         * not a problem
         *
         * For example, if "Implicit return value" is enabled, methods will
         * always return a value
         */
        if (!predefined->info.expected_btypes) {
                goto exit;
        }

        /*
         * Check that the type of the return object is what is expected for
         * this predefined name
         */
        status = acpi_ns_check_object_type(pathname, return_object,
                                           predefined->info.expected_btypes,
                                           ACPI_NOT_PACKAGE);
        if (ACPI_FAILURE(status)) {
                goto exit;
        }

        /* For returned Package objects, check the type of all sub-objects */

        if (ACPI_GET_OBJECT_TYPE(return_object) == ACPI_TYPE_PACKAGE) {
                status =
                    acpi_ns_check_package(pathname, return_object, predefined);
        }

      exit:
        if (pathname) {
                ACPI_FREE(pathname);
        }

        return (status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_check_parameter_count
 *
 * PARAMETERS:  Pathname        - Full pathname to the node (for error msgs)
 *              Node            - Namespace node for the method/object
 *              Predefined      - Pointer to entry in predefined name table
 *
 * RETURN:      None
 *
 * DESCRIPTION: Check that the declared (in ASL/AML) parameter count for a
 *              predefined name is what is expected (i.e., what is defined in
 *              the ACPI specification for this predefined name.)
 *
 ******************************************************************************/

void
acpi_ns_check_parameter_count(char *pathname,
                              struct acpi_namespace_node *node,
                              const union acpi_predefined_info *predefined)
{
        u32 param_count;
        u32 required_params_current;
        u32 required_params_old;

        /*
         * Check that the ASL-defined parameter count is what is expected for
         * this predefined name.
         *
         * Methods have 0-7 parameters. All other types have zero.
         */
        param_count = 0;
        if (node->type == ACPI_TYPE_METHOD) {
                param_count = node->object->method.param_count;
        }

        /* Validate parameter count - allow two different legal counts (_SCP) */

        required_params_current = predefined->info.param_count & 0x0F;
        required_params_old = predefined->info.param_count >> 4;

        if ((param_count != required_params_current) &&
            (param_count != required_params_old)) {
                ACPI_WARNING((AE_INFO,
                              "%s: Parameter count mismatch - ASL declared %d, expected %d",
                              pathname, param_count, required_params_current));
        }
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_check_for_predefined_name
 *
 * PARAMETERS:  Node            - Namespace node for the method/object
 *
 * RETURN:      Pointer to entry in predefined table. NULL indicates not found.
 *
 * DESCRIPTION: Check an object name against the predefined object list.
 *
 ******************************************************************************/

const union acpi_predefined_info *acpi_ns_check_for_predefined_name(struct
                                                                    acpi_namespace_node
                                                                    *node)
{
        const union acpi_predefined_info *this_name;

        /* Quick check for a predefined name, first character must be underscore */

        if (node->name.ascii[0] != '_') {
                return (NULL);
        }

        /* Search info table for a predefined method/object name */

        this_name = predefined_names;
        while (this_name->info.name[0]) {
                if (ACPI_COMPARE_NAME(node->name.ascii, this_name->info.name)) {

                        /* Return pointer to this table entry */

                        return (this_name);
                }

                /*
                 * Skip next entry in the table if this name returns a Package
                 * (next entry contains the package info)
                 */
                if (this_name->info.expected_btypes & ACPI_RTYPE_PACKAGE) {
                        this_name++;
                }

                this_name++;
        }

        return (NULL);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_check_package
 *
 * PARAMETERS:  Pathname        - Full pathname to the node (for error msgs)
 *              return_object   - Object returned from the evaluation of a
 *                                method or object
 *              Predefined      - Pointer to entry in predefined name table
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Check a returned package object for the correct count and
 *              correct type of all sub-objects.
 *
 ******************************************************************************/

static acpi_status
acpi_ns_check_package(char *pathname,
                      union acpi_operand_object *return_object,
                      const union acpi_predefined_info *predefined)
{
        const union acpi_predefined_info *package;
        union acpi_operand_object *sub_package;
        union acpi_operand_object **elements;
        union acpi_operand_object **sub_elements;
        acpi_status status;
        u32 expected_count;
        u32 count;
        u32 i;
        u32 j;

        ACPI_FUNCTION_NAME(ns_check_package);

        /* The package info for this name is in the next table entry */

        package = predefined + 1;

        ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
                          "%s Validating return Package of Type %X, Count %X\n",
                          pathname, package->ret_info.type,
                          return_object->package.count));

        /* Extract package count and elements array */

        elements = return_object->package.elements;
        count = return_object->package.count;

        /* The package must have at least one element, else invalid */

        if (!count) {
                ACPI_WARNING((AE_INFO,
                              "%s: Return Package has no elements (empty)",
                              pathname));

                return (AE_AML_OPERAND_VALUE);
        }

        /*
         * Decode the type of the expected package contents
         *
         * PTYPE1 packages contain no subpackages
         * PTYPE2 packages contain sub-packages
         */
        switch (package->ret_info.type) {
        case ACPI_PTYPE1_FIXED:

                /*
                 * The package count is fixed and there are no sub-packages
                 *
                 * If package is too small, exit.
                 * If package is larger than expected, issue warning but continue
                 */
                expected_count =
                    package->ret_info.count1 + package->ret_info.count2;
                if (count < expected_count) {
                        goto package_too_small;
                } else if (count > expected_count) {
                        ACPI_WARNING((AE_INFO,
                                      "%s: Return Package is larger than needed - "
                                      "found %u, expected %u", pathname, count,
                                      expected_count));
                }

                /* Validate all elements of the returned package */

                status = acpi_ns_check_package_elements(pathname, elements,
                                                        package->ret_info.
                                                        object_type1,
                                                        package->ret_info.
                                                        count1,
                                                        package->ret_info.
                                                        object_type2,
                                                        package->ret_info.
                                                        count2);
                if (ACPI_FAILURE(status)) {
                        return (status);
                }
                break;

        case ACPI_PTYPE1_VAR:

                /*
                 * The package count is variable, there are no sub-packages, and all
                 * elements must be of the same type
                 */
                for (i = 0; i < count; i++) {
                        status = acpi_ns_check_object_type(pathname, *elements,
                                                           package->ret_info.
                                                           object_type1, i);
                        if (ACPI_FAILURE(status)) {
                                return (status);
                        }
                        elements++;
                }
                break;

        case ACPI_PTYPE1_OPTION:

                /*
                 * The package count is variable, there are no sub-packages. There are
                 * a fixed number of required elements, and a variable number of
                 * optional elements.
                 *
                 * Check if package is at least as large as the minimum required
                 */
                expected_count = package->ret_info3.count;
                if (count < expected_count) {
                        goto package_too_small;
                }

                /* Variable number of sub-objects */

                for (i = 0; i < count; i++) {
                        if (i < package->ret_info3.count) {

                                /* These are the required package elements (0, 1, or 2) */

                                status =
                                    acpi_ns_check_object_type(pathname,
                                                              *elements,
                                                              package->
                                                              ret_info3.
                                                              object_type[i],
                                                              i);
                                if (ACPI_FAILURE(status)) {
                                        return (status);
                                }
                        } else {
                                /* These are the optional package elements */

                                status =
                                    acpi_ns_check_object_type(pathname,
                                                              *elements,
                                                              package->
                                                              ret_info3.
                                                              tail_object_type,
                                                              i);
                                if (ACPI_FAILURE(status)) {
                                        return (status);
                                }
                        }
                        elements++;
                }
                break;

        case ACPI_PTYPE2_PKG_COUNT:

                /* First element is the (Integer) count of sub-packages to follow */

                status = acpi_ns_check_object_type(pathname, *elements,
                                                   ACPI_RTYPE_INTEGER, 0);
                if (ACPI_FAILURE(status)) {
                        return (status);
                }

                /*
                 * Count cannot be larger than the parent package length, but allow it
                 * to be smaller. The >= accounts for the Integer above.
                 */
                expected_count = (u32) (*elements)->integer.value;
                if (expected_count >= count) {
                        goto package_too_small;
                }

                count = expected_count;
                elements++;

                /* Now we can walk the sub-packages */

                /*lint -fallthrough */

        case ACPI_PTYPE2:
        case ACPI_PTYPE2_FIXED:
        case ACPI_PTYPE2_MIN:
        case ACPI_PTYPE2_COUNT:

                /*
                 * These types all return a single package that consists of a variable
                 * number of sub-packages
                 */
                for (i = 0; i < count; i++) {
                        sub_package = *elements;
                        sub_elements = sub_package->package.elements;

                        /* Each sub-object must be of type Package */

                        status =
                            acpi_ns_check_object_type(pathname, sub_package,
                                                      ACPI_RTYPE_PACKAGE, i);
                        if (ACPI_FAILURE(status)) {
                                return (status);
                        }

                        /* Examine the different types of sub-packages */

                        switch (package->ret_info.type) {
                        case ACPI_PTYPE2:
                        case ACPI_PTYPE2_PKG_COUNT:

                                /* Each subpackage has a fixed number of elements */

                                expected_count =
                                    package->ret_info.count1 +
                                    package->ret_info.count2;
                                if (sub_package->package.count !=
                                    expected_count) {
                                        count = sub_package->package.count;
                                        goto package_too_small;
                                }

                                status =
                                    acpi_ns_check_package_elements(pathname,
                                                                   sub_elements,
                                                                   package->
                                                                   ret_info.
                                                                   object_type1,
                                                                   package->
                                                                   ret_info.
                                                                   count1,
                                                                   package->
                                                                   ret_info.
                                                                   object_type2,
                                                                   package->
                                                                   ret_info.
                                                                   count2);
                                if (ACPI_FAILURE(status)) {
                                        return (status);
                                }
                                break;

                        case ACPI_PTYPE2_FIXED:

                                /* Each sub-package has a fixed length */

                                expected_count = package->ret_info2.count;
                                if (sub_package->package.count < expected_count) {
                                        count = sub_package->package.count;
                                        goto package_too_small;
                                }

                                /* Check the type of each sub-package element */

                                for (j = 0; j < expected_count; j++) {
                                        status =
                                            acpi_ns_check_object_type(pathname,
                                                                      sub_elements
                                                                      [j],
                                                                      package->
                                                                      ret_info2.
                                                                      object_type
                                                                      [j], j);
                                        if (ACPI_FAILURE(status)) {
                                                return (status);
                                        }
                                }
                                break;

                        case ACPI_PTYPE2_MIN:

                                /* Each sub-package has a variable but minimum length */

                                expected_count = package->ret_info.count1;
                                if (sub_package->package.count < expected_count) {
                                        count = sub_package->package.count;
                                        goto package_too_small;
                                }

                                /* Check the type of each sub-package element */

                                status =
                                    acpi_ns_check_package_elements(pathname,
                                                                   sub_elements,
                                                                   package->
                                                                   ret_info.
                                                                   object_type1,
                                                                   sub_package->
                                                                   package.
                                                                   count, 0, 0);
                                if (ACPI_FAILURE(status)) {
                                        return (status);
                                }
                                break;

                        case ACPI_PTYPE2_COUNT:

                                /* First element is the (Integer) count of elements to follow */

                                status =
                                    acpi_ns_check_object_type(pathname,
                                                              *sub_elements,
                                                              ACPI_RTYPE_INTEGER,
                                                              0);
                                if (ACPI_FAILURE(status)) {
                                        return (status);
                                }

                                /* Make sure package is large enough for the Count */

                                expected_count =
                                    (u32) (*sub_elements)->integer.value;
                                if (sub_package->package.count < expected_count) {
                                        count = sub_package->package.count;
                                        goto package_too_small;
                                }

                                /* Check the type of each sub-package element */

                                status =
                                    acpi_ns_check_package_elements(pathname,
                                                                   (sub_elements
                                                                    + 1),
                                                                   package->
                                                                   ret_info.
                                                                   object_type1,
                                                                   (expected_count
                                                                    - 1), 0, 0);
                                if (ACPI_FAILURE(status)) {
                                        return (status);
                                }
                                break;

                        default:
                                break;
                        }

                        elements++;
                }
                break;

        default:

                /* Should not get here if predefined info table is correct */

                ACPI_WARNING((AE_INFO,
                              "%s: Invalid internal return type in table entry: %X",
                              pathname, package->ret_info.type));

                return (AE_AML_INTERNAL);
        }

        return (AE_OK);

      package_too_small:

        /* Error exit for the case with an incorrect package count */

        ACPI_WARNING((AE_INFO, "%s: Return Package is too small - "
                      "found %u, expected %u", pathname, count,
                      expected_count));

        return (AE_AML_OPERAND_VALUE);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_check_package_elements
 *
 * PARAMETERS:  Pathname        - Full pathname to the node (for error msgs)
 *              Elements        - Pointer to the package elements array
 *              Type1           - Object type for first group
 *              Count1          - Count for first group
 *              Type2           - Object type for second group
 *              Count2          - Count for second group
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Check that all elements of a package are of the correct object
 *              type. Supports up to two groups of different object types.
 *
 ******************************************************************************/

static acpi_status
acpi_ns_check_package_elements(char *pathname,
                               union acpi_operand_object **elements,
                               u8 type1, u32 count1, u8 type2, u32 count2)
{
        union acpi_operand_object **this_element = elements;
        acpi_status status;
        u32 i;

        /*
         * Up to two groups of package elements are supported by the data
         * structure. All elements in each group must be of the same type.
         * The second group can have a count of zero.
         */
        for (i = 0; i < count1; i++) {
                status = acpi_ns_check_object_type(pathname, *this_element,
                                                   type1, i);
                if (ACPI_FAILURE(status)) {
                        return (status);
                }
                this_element++;
        }

        for (i = 0; i < count2; i++) {
                status = acpi_ns_check_object_type(pathname, *this_element,
                                                   type2, (i + count1));
                if (ACPI_FAILURE(status)) {
                        return (status);
                }
                this_element++;
        }

        return (AE_OK);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_check_object_type
 *
 * PARAMETERS:  Pathname        - Full pathname to the node (for error msgs)
 *              return_object   - Object return from the execution of this
 *                                method/object
 *              expected_btypes - Bitmap of expected return type(s)
 *              package_index   - Index of object within parent package (if
 *                                applicable - ACPI_NOT_PACKAGE otherwise)
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Check the type of the return object against the expected object
 *              type(s). Use of Btype allows multiple expected object types.
 *
 ******************************************************************************/

static acpi_status
acpi_ns_check_object_type(char *pathname,
                          union acpi_operand_object *return_object,
                          u32 expected_btypes, u32 package_index)
{
        acpi_status status = AE_OK;
        u32 return_btype;
        char type_buffer[48];   /* Room for 5 types */
        u32 this_rtype;
        u32 i;
        u32 j;

        /*
         * If we get a NULL return_object here, it is a NULL package element,
         * and this is always an error.
         */
        if (!return_object) {
                goto type_error_exit;
        }

        /* A Namespace node should not get here, but make sure */

        if (ACPI_GET_DESCRIPTOR_TYPE(return_object) == ACPI_DESC_TYPE_NAMED) {
                ACPI_WARNING((AE_INFO,
                              "%s: Invalid return type - Found a Namespace node [%4.4s] type %s",
                              pathname, return_object->node.name.ascii,
                              acpi_ut_get_type_name(return_object->node.type)));
                return (AE_AML_OPERAND_TYPE);
        }

        /*
         * Convert the object type (ACPI_TYPE_xxx) to a bitmapped object type.
         * The bitmapped type allows multiple possible return types.
         *
         * Note, the cases below must handle all of the possible types returned
         * from all of the predefined names (including elements of returned
         * packages)
         */
        switch (ACPI_GET_OBJECT_TYPE(return_object)) {
        case ACPI_TYPE_INTEGER:
                return_btype = ACPI_RTYPE_INTEGER;
                break;

        case ACPI_TYPE_BUFFER:
                return_btype = ACPI_RTYPE_BUFFER;
                break;

        case ACPI_TYPE_STRING:
                return_btype = ACPI_RTYPE_STRING;
                break;

        case ACPI_TYPE_PACKAGE:
                return_btype = ACPI_RTYPE_PACKAGE;
                break;

        case ACPI_TYPE_LOCAL_REFERENCE:
                return_btype = ACPI_RTYPE_REFERENCE;
                break;

        default:
                /* Not one of the supported objects, must be incorrect */

                goto type_error_exit;
        }

        /* Is the object one of the expected types? */

        if (!(return_btype & expected_btypes)) {
                goto type_error_exit;
        }

        /* For reference objects, check that the reference type is correct */

        if (ACPI_GET_OBJECT_TYPE(return_object) == ACPI_TYPE_LOCAL_REFERENCE) {
                status = acpi_ns_check_reference(pathname, return_object);
        }

        return (status);

      type_error_exit:

        /* Create a string with all expected types for this predefined object */

        j = 1;
        type_buffer[0] = 0;
        this_rtype = ACPI_RTYPE_INTEGER;

        for (i = 0; i < ACPI_NUM_RTYPES; i++) {

                /* If one of the expected types, concatenate the name of this type */

                if (expected_btypes & this_rtype) {
                        ACPI_STRCAT(type_buffer, &acpi_rtype_names[i][j]);
                        j = 0;  /* Use name separator from now on */
                }
                this_rtype <<= 1;       /* Next Rtype */
        }

        if (package_index == ACPI_NOT_PACKAGE) {
                ACPI_WARNING((AE_INFO,
                              "%s: Return type mismatch - found %s, expected %s",
                              pathname,
                              acpi_ut_get_object_type_name(return_object),
                              type_buffer));
        } else {
                ACPI_WARNING((AE_INFO,
                              "%s: Return Package type mismatch at index %u - "
                              "found %s, expected %s", pathname, package_index,
                              acpi_ut_get_object_type_name(return_object),
                              type_buffer));
        }

        return (AE_AML_OPERAND_TYPE);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_check_reference
 *
 * PARAMETERS:  Pathname        - Full pathname to the node (for error msgs)
 *              return_object   - Object returned from the evaluation of a
 *                                method or object
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Check a returned reference object for the correct reference
 *              type. The only reference type that can be returned from a
 *              predefined method is a named reference. All others are invalid.
 *
 ******************************************************************************/

static acpi_status
acpi_ns_check_reference(char *pathname,
                        union acpi_operand_object *return_object)
{

        /*
         * Check the reference object for the correct reference type (opcode).
         * The only type of reference that can be converted to an union acpi_object is
         * a reference to a named object (reference class: NAME)
         */
        if (return_object->reference.class == ACPI_REFCLASS_NAME) {
                return (AE_OK);
        }

        ACPI_WARNING((AE_INFO,
                      "%s: Return type mismatch - unexpected reference object type [%s] %2.2X",
                      pathname, acpi_ut_get_reference_name(return_object),
                      return_object->reference.class));

        return (AE_AML_OPERAND_TYPE);
}