xref: /freebsd/sys/contrib/dev/acpica/components/namespace/nsutils.c (revision 74036c4de983981ee2b23f91e285363293aa7c3c)
1 /******************************************************************************
2  *
3  * Module Name: nsutils - Utilities for accessing ACPI namespace, accessing
4  *                        parents and siblings and Scope manipulation
5  *
6  *****************************************************************************/
7 
8 /*
9  * Copyright (C) 2000 - 2013, Intel Corp.
10  * All rights reserved.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions, and the following disclaimer,
17  *    without modification.
18  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
19  *    substantially similar to the "NO WARRANTY" disclaimer below
20  *    ("Disclaimer") and any redistribution must be conditioned upon
21  *    including a substantially similar Disclaimer requirement for further
22  *    binary redistribution.
23  * 3. Neither the names of the above-listed copyright holders nor the names
24  *    of any contributors may be used to endorse or promote products derived
25  *    from this software without specific prior written permission.
26  *
27  * Alternatively, this software may be distributed under the terms of the
28  * GNU General Public License ("GPL") version 2 as published by the Free
29  * Software Foundation.
30  *
31  * NO WARRANTY
32  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
33  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
34  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
35  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
36  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
37  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
38  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
39  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
40  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
41  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
42  * POSSIBILITY OF SUCH DAMAGES.
43  */
44 
45 #define __NSUTILS_C__
46 
47 #include <contrib/dev/acpica/include/acpi.h>
48 #include <contrib/dev/acpica/include/accommon.h>
49 #include <contrib/dev/acpica/include/acnamesp.h>
50 #include <contrib/dev/acpica/include/amlcode.h>
51 
52 #define _COMPONENT          ACPI_NAMESPACE
53         ACPI_MODULE_NAME    ("nsutils")
54 
55 /* Local prototypes */
56 
57 #ifdef ACPI_OBSOLETE_FUNCTIONS
58 ACPI_NAME
59 AcpiNsFindParentName (
60     ACPI_NAMESPACE_NODE     *NodeToSearch);
61 #endif
62 
63 
64 /*******************************************************************************
65  *
66  * FUNCTION:    AcpiNsPrintNodePathname
67  *
68  * PARAMETERS:  Node            - Object
69  *              Message         - Prefix message
70  *
71  * DESCRIPTION: Print an object's full namespace pathname
72  *              Manages allocation/freeing of a pathname buffer
73  *
74  ******************************************************************************/
75 
76 void
77 AcpiNsPrintNodePathname (
78     ACPI_NAMESPACE_NODE     *Node,
79     const char              *Message)
80 {
81     ACPI_BUFFER             Buffer;
82     ACPI_STATUS             Status;
83 
84 
85     if (!Node)
86     {
87         AcpiOsPrintf ("[NULL NAME]");
88         return;
89     }
90 
91     /* Convert handle to full pathname and print it (with supplied message) */
92 
93     Buffer.Length = ACPI_ALLOCATE_LOCAL_BUFFER;
94 
95     Status = AcpiNsHandleToPathname (Node, &Buffer);
96     if (ACPI_SUCCESS (Status))
97     {
98         if (Message)
99         {
100             AcpiOsPrintf ("%s ", Message);
101         }
102 
103         AcpiOsPrintf ("[%s] (Node %p)", (char *) Buffer.Pointer, Node);
104         ACPI_FREE (Buffer.Pointer);
105     }
106 }
107 
108 
109 /*******************************************************************************
110  *
111  * FUNCTION:    AcpiNsGetType
112  *
113  * PARAMETERS:  Node        - Parent Node to be examined
114  *
115  * RETURN:      Type field from Node whose handle is passed
116  *
117  * DESCRIPTION: Return the type of a Namespace node
118  *
119  ******************************************************************************/
120 
121 ACPI_OBJECT_TYPE
122 AcpiNsGetType (
123     ACPI_NAMESPACE_NODE     *Node)
124 {
125     ACPI_FUNCTION_TRACE (NsGetType);
126 
127 
128     if (!Node)
129     {
130         ACPI_WARNING ((AE_INFO, "Null Node parameter"));
131         return_UINT8 (ACPI_TYPE_ANY);
132     }
133 
134     return_UINT8 (Node->Type);
135 }
136 
137 
138 /*******************************************************************************
139  *
140  * FUNCTION:    AcpiNsLocal
141  *
142  * PARAMETERS:  Type        - A namespace object type
143  *
144  * RETURN:      LOCAL if names must be found locally in objects of the
145  *              passed type, 0 if enclosing scopes should be searched
146  *
147  * DESCRIPTION: Returns scope rule for the given object type.
148  *
149  ******************************************************************************/
150 
151 UINT32
152 AcpiNsLocal (
153     ACPI_OBJECT_TYPE        Type)
154 {
155     ACPI_FUNCTION_TRACE (NsLocal);
156 
157 
158     if (!AcpiUtValidObjectType (Type))
159     {
160         /* Type code out of range  */
161 
162         ACPI_WARNING ((AE_INFO, "Invalid Object Type 0x%X", Type));
163         return_UINT32 (ACPI_NS_NORMAL);
164     }
165 
166     return_UINT32 (AcpiGbl_NsProperties[Type] & ACPI_NS_LOCAL);
167 }
168 
169 
170 /*******************************************************************************
171  *
172  * FUNCTION:    AcpiNsGetInternalNameLength
173  *
174  * PARAMETERS:  Info            - Info struct initialized with the
175  *                                external name pointer.
176  *
177  * RETURN:      None
178  *
179  * DESCRIPTION: Calculate the length of the internal (AML) namestring
180  *              corresponding to the external (ASL) namestring.
181  *
182  ******************************************************************************/
183 
184 void
185 AcpiNsGetInternalNameLength (
186     ACPI_NAMESTRING_INFO    *Info)
187 {
188     const char              *NextExternalChar;
189     UINT32                  i;
190 
191 
192     ACPI_FUNCTION_ENTRY ();
193 
194 
195     NextExternalChar = Info->ExternalName;
196     Info->NumCarats = 0;
197     Info->NumSegments = 0;
198     Info->FullyQualified = FALSE;
199 
200     /*
201      * For the internal name, the required length is 4 bytes per segment, plus
202      * 1 each for RootPrefix, MultiNamePrefixOp, segment count, trailing null
203      * (which is not really needed, but no there's harm in putting it there)
204      *
205      * strlen() + 1 covers the first NameSeg, which has no path separator
206      */
207     if (ACPI_IS_ROOT_PREFIX (*NextExternalChar))
208     {
209         Info->FullyQualified = TRUE;
210         NextExternalChar++;
211 
212         /* Skip redundant RootPrefix, like \\_SB.PCI0.SBRG.EC0 */
213 
214         while (ACPI_IS_ROOT_PREFIX (*NextExternalChar))
215         {
216             NextExternalChar++;
217         }
218     }
219     else
220     {
221         /* Handle Carat prefixes */
222 
223         while (ACPI_IS_PARENT_PREFIX (*NextExternalChar))
224         {
225             Info->NumCarats++;
226             NextExternalChar++;
227         }
228     }
229 
230     /*
231      * Determine the number of ACPI name "segments" by counting the number of
232      * path separators within the string. Start with one segment since the
233      * segment count is [(# separators) + 1], and zero separators is ok.
234      */
235     if (*NextExternalChar)
236     {
237         Info->NumSegments = 1;
238         for (i = 0; NextExternalChar[i]; i++)
239         {
240             if (ACPI_IS_PATH_SEPARATOR (NextExternalChar[i]))
241             {
242                 Info->NumSegments++;
243             }
244         }
245     }
246 
247     Info->Length = (ACPI_NAME_SIZE * Info->NumSegments) +
248                     4 + Info->NumCarats;
249 
250     Info->NextExternalChar = NextExternalChar;
251 }
252 
253 
254 /*******************************************************************************
255  *
256  * FUNCTION:    AcpiNsBuildInternalName
257  *
258  * PARAMETERS:  Info            - Info struct fully initialized
259  *
260  * RETURN:      Status
261  *
262  * DESCRIPTION: Construct the internal (AML) namestring
263  *              corresponding to the external (ASL) namestring.
264  *
265  ******************************************************************************/
266 
267 ACPI_STATUS
268 AcpiNsBuildInternalName (
269     ACPI_NAMESTRING_INFO    *Info)
270 {
271     UINT32                  NumSegments = Info->NumSegments;
272     char                    *InternalName = Info->InternalName;
273     const char              *ExternalName = Info->NextExternalChar;
274     char                    *Result = NULL;
275     UINT32                  i;
276 
277 
278     ACPI_FUNCTION_TRACE (NsBuildInternalName);
279 
280 
281     /* Setup the correct prefixes, counts, and pointers */
282 
283     if (Info->FullyQualified)
284     {
285         InternalName[0] = AML_ROOT_PREFIX;
286 
287         if (NumSegments <= 1)
288         {
289             Result = &InternalName[1];
290         }
291         else if (NumSegments == 2)
292         {
293             InternalName[1] = AML_DUAL_NAME_PREFIX;
294             Result = &InternalName[2];
295         }
296         else
297         {
298             InternalName[1] = AML_MULTI_NAME_PREFIX_OP;
299             InternalName[2] = (char) NumSegments;
300             Result = &InternalName[3];
301         }
302     }
303     else
304     {
305         /*
306          * Not fully qualified.
307          * Handle Carats first, then append the name segments
308          */
309         i = 0;
310         if (Info->NumCarats)
311         {
312             for (i = 0; i < Info->NumCarats; i++)
313             {
314                 InternalName[i] = AML_PARENT_PREFIX;
315             }
316         }
317 
318         if (NumSegments <= 1)
319         {
320             Result = &InternalName[i];
321         }
322         else if (NumSegments == 2)
323         {
324             InternalName[i] = AML_DUAL_NAME_PREFIX;
325             Result = &InternalName[(ACPI_SIZE) i+1];
326         }
327         else
328         {
329             InternalName[i] = AML_MULTI_NAME_PREFIX_OP;
330             InternalName[(ACPI_SIZE) i+1] = (char) NumSegments;
331             Result = &InternalName[(ACPI_SIZE) i+2];
332         }
333     }
334 
335     /* Build the name (minus path separators) */
336 
337     for (; NumSegments; NumSegments--)
338     {
339         for (i = 0; i < ACPI_NAME_SIZE; i++)
340         {
341             if (ACPI_IS_PATH_SEPARATOR (*ExternalName) ||
342                (*ExternalName == 0))
343             {
344                 /* Pad the segment with underscore(s) if segment is short */
345 
346                 Result[i] = '_';
347             }
348             else
349             {
350                 /* Convert the character to uppercase and save it */
351 
352                 Result[i] = (char) ACPI_TOUPPER ((int) *ExternalName);
353                 ExternalName++;
354             }
355         }
356 
357         /* Now we must have a path separator, or the pathname is bad */
358 
359         if (!ACPI_IS_PATH_SEPARATOR (*ExternalName) &&
360             (*ExternalName != 0))
361         {
362             return_ACPI_STATUS (AE_BAD_PATHNAME);
363         }
364 
365         /* Move on the next segment */
366 
367         ExternalName++;
368         Result += ACPI_NAME_SIZE;
369     }
370 
371     /* Terminate the string */
372 
373     *Result = 0;
374 
375     if (Info->FullyQualified)
376     {
377         ACPI_DEBUG_PRINT ((ACPI_DB_EXEC, "Returning [%p] (abs) \"\\%s\"\n",
378             InternalName, InternalName));
379     }
380     else
381     {
382         ACPI_DEBUG_PRINT ((ACPI_DB_EXEC, "Returning [%p] (rel) \"%s\"\n",
383             InternalName, InternalName));
384     }
385 
386     return_ACPI_STATUS (AE_OK);
387 }
388 
389 
390 /*******************************************************************************
391  *
392  * FUNCTION:    AcpiNsInternalizeName
393  *
394  * PARAMETERS:  *ExternalName           - External representation of name
395  *              **Converted Name        - Where to return the resulting
396  *                                        internal represention of the name
397  *
398  * RETURN:      Status
399  *
400  * DESCRIPTION: Convert an external representation (e.g. "\_PR_.CPU0")
401  *              to internal form (e.g. 5c 2f 02 5f 50 52 5f 43 50 55 30)
402  *
403  *******************************************************************************/
404 
405 ACPI_STATUS
406 AcpiNsInternalizeName (
407     const char              *ExternalName,
408     char                    **ConvertedName)
409 {
410     char                    *InternalName;
411     ACPI_NAMESTRING_INFO    Info;
412     ACPI_STATUS             Status;
413 
414 
415     ACPI_FUNCTION_TRACE (NsInternalizeName);
416 
417 
418     if ((!ExternalName)      ||
419         (*ExternalName == 0) ||
420         (!ConvertedName))
421     {
422         return_ACPI_STATUS (AE_BAD_PARAMETER);
423     }
424 
425     /* Get the length of the new internal name */
426 
427     Info.ExternalName = ExternalName;
428     AcpiNsGetInternalNameLength (&Info);
429 
430     /* We need a segment to store the internal  name */
431 
432     InternalName = ACPI_ALLOCATE_ZEROED (Info.Length);
433     if (!InternalName)
434     {
435         return_ACPI_STATUS (AE_NO_MEMORY);
436     }
437 
438     /* Build the name */
439 
440     Info.InternalName = InternalName;
441     Status = AcpiNsBuildInternalName (&Info);
442     if (ACPI_FAILURE (Status))
443     {
444         ACPI_FREE (InternalName);
445         return_ACPI_STATUS (Status);
446     }
447 
448     *ConvertedName = InternalName;
449     return_ACPI_STATUS (AE_OK);
450 }
451 
452 
453 /*******************************************************************************
454  *
455  * FUNCTION:    AcpiNsExternalizeName
456  *
457  * PARAMETERS:  InternalNameLength  - Lenth of the internal name below
458  *              InternalName        - Internal representation of name
459  *              ConvertedNameLength - Where the length is returned
460  *              ConvertedName       - Where the resulting external name
461  *                                    is returned
462  *
463  * RETURN:      Status
464  *
465  * DESCRIPTION: Convert internal name (e.g. 5c 2f 02 5f 50 52 5f 43 50 55 30)
466  *              to its external (printable) form (e.g. "\_PR_.CPU0")
467  *
468  ******************************************************************************/
469 
470 ACPI_STATUS
471 AcpiNsExternalizeName (
472     UINT32                  InternalNameLength,
473     const char              *InternalName,
474     UINT32                  *ConvertedNameLength,
475     char                    **ConvertedName)
476 {
477     UINT32                  NamesIndex = 0;
478     UINT32                  NumSegments = 0;
479     UINT32                  RequiredLength;
480     UINT32                  PrefixLength = 0;
481     UINT32                  i = 0;
482     UINT32                  j = 0;
483 
484 
485     ACPI_FUNCTION_TRACE (NsExternalizeName);
486 
487 
488     if (!InternalNameLength     ||
489         !InternalName           ||
490         !ConvertedName)
491     {
492         return_ACPI_STATUS (AE_BAD_PARAMETER);
493     }
494 
495     /* Check for a prefix (one '\' | one or more '^') */
496 
497     switch (InternalName[0])
498     {
499     case AML_ROOT_PREFIX:
500 
501         PrefixLength = 1;
502         break;
503 
504     case AML_PARENT_PREFIX:
505 
506         for (i = 0; i < InternalNameLength; i++)
507         {
508             if (ACPI_IS_PARENT_PREFIX (InternalName[i]))
509             {
510                 PrefixLength = i + 1;
511             }
512             else
513             {
514                 break;
515             }
516         }
517 
518         if (i == InternalNameLength)
519         {
520             PrefixLength = i;
521         }
522 
523         break;
524 
525     default:
526 
527         break;
528     }
529 
530     /*
531      * Check for object names. Note that there could be 0-255 of these
532      * 4-byte elements.
533      */
534     if (PrefixLength < InternalNameLength)
535     {
536         switch (InternalName[PrefixLength])
537         {
538         case AML_MULTI_NAME_PREFIX_OP:
539 
540             /* <count> 4-byte names */
541 
542             NamesIndex = PrefixLength + 2;
543             NumSegments = (UINT8)
544                 InternalName[(ACPI_SIZE) PrefixLength + 1];
545             break;
546 
547         case AML_DUAL_NAME_PREFIX:
548 
549             /* Two 4-byte names */
550 
551             NamesIndex = PrefixLength + 1;
552             NumSegments = 2;
553             break;
554 
555         case 0:
556 
557             /* NullName */
558 
559             NamesIndex = 0;
560             NumSegments = 0;
561             break;
562 
563         default:
564 
565             /* one 4-byte name */
566 
567             NamesIndex = PrefixLength;
568             NumSegments = 1;
569             break;
570         }
571     }
572 
573     /*
574      * Calculate the length of ConvertedName, which equals the length
575      * of the prefix, length of all object names, length of any required
576      * punctuation ('.') between object names, plus the NULL terminator.
577      */
578     RequiredLength = PrefixLength + (4 * NumSegments) +
579                         ((NumSegments > 0) ? (NumSegments - 1) : 0) + 1;
580 
581     /*
582      * Check to see if we're still in bounds. If not, there's a problem
583      * with InternalName (invalid format).
584      */
585     if (RequiredLength > InternalNameLength)
586     {
587         ACPI_ERROR ((AE_INFO, "Invalid internal name"));
588         return_ACPI_STATUS (AE_BAD_PATHNAME);
589     }
590 
591     /* Build the ConvertedName */
592 
593     *ConvertedName = ACPI_ALLOCATE_ZEROED (RequiredLength);
594     if (!(*ConvertedName))
595     {
596         return_ACPI_STATUS (AE_NO_MEMORY);
597     }
598 
599     j = 0;
600 
601     for (i = 0; i < PrefixLength; i++)
602     {
603         (*ConvertedName)[j++] = InternalName[i];
604     }
605 
606     if (NumSegments > 0)
607     {
608         for (i = 0; i < NumSegments; i++)
609         {
610             if (i > 0)
611             {
612                 (*ConvertedName)[j++] = '.';
613             }
614 
615             /* Copy and validate the 4-char name segment */
616 
617             ACPI_MOVE_NAME (&(*ConvertedName)[j], &InternalName[NamesIndex]);
618             AcpiUtRepairName (&(*ConvertedName)[j]);
619 
620             j += ACPI_NAME_SIZE;
621             NamesIndex += ACPI_NAME_SIZE;
622         }
623     }
624 
625     if (ConvertedNameLength)
626     {
627         *ConvertedNameLength = (UINT32) RequiredLength;
628     }
629 
630     return_ACPI_STATUS (AE_OK);
631 }
632 
633 
634 /*******************************************************************************
635  *
636  * FUNCTION:    AcpiNsValidateHandle
637  *
638  * PARAMETERS:  Handle          - Handle to be validated and typecast to a
639  *                                namespace node.
640  *
641  * RETURN:      A pointer to a namespace node
642  *
643  * DESCRIPTION: Convert a namespace handle to a namespace node. Handles special
644  *              cases for the root node.
645  *
646  * NOTE: Real integer handles would allow for more verification
647  *       and keep all pointers within this subsystem - however this introduces
648  *       more overhead and has not been necessary to this point. Drivers
649  *       holding handles are typically notified before a node becomes invalid
650  *       due to a table unload.
651  *
652  ******************************************************************************/
653 
654 ACPI_NAMESPACE_NODE *
655 AcpiNsValidateHandle (
656     ACPI_HANDLE             Handle)
657 {
658 
659     ACPI_FUNCTION_ENTRY ();
660 
661 
662     /* Parameter validation */
663 
664     if ((!Handle) || (Handle == ACPI_ROOT_OBJECT))
665     {
666         return (AcpiGbl_RootNode);
667     }
668 
669     /* We can at least attempt to verify the handle */
670 
671     if (ACPI_GET_DESCRIPTOR_TYPE (Handle) != ACPI_DESC_TYPE_NAMED)
672     {
673         return (NULL);
674     }
675 
676     return (ACPI_CAST_PTR (ACPI_NAMESPACE_NODE, Handle));
677 }
678 
679 
680 /*******************************************************************************
681  *
682  * FUNCTION:    AcpiNsTerminate
683  *
684  * PARAMETERS:  none
685  *
686  * RETURN:      none
687  *
688  * DESCRIPTION: free memory allocated for namespace and ACPI table storage.
689  *
690  ******************************************************************************/
691 
692 void
693 AcpiNsTerminate (
694     void)
695 {
696     ACPI_OPERAND_OBJECT     *ObjDesc;
697 
698 
699     ACPI_FUNCTION_TRACE (NsTerminate);
700 
701 
702     /*
703      * 1) Free the entire namespace -- all nodes and objects
704      *
705      * Delete all object descriptors attached to namepsace nodes
706      */
707     AcpiNsDeleteNamespaceSubtree (AcpiGbl_RootNode);
708 
709     /* Detach any objects attached to the root */
710 
711     ObjDesc = AcpiNsGetAttachedObject (AcpiGbl_RootNode);
712     if (ObjDesc)
713     {
714         AcpiNsDetachObject (AcpiGbl_RootNode);
715     }
716 
717     ACPI_DEBUG_PRINT ((ACPI_DB_INFO, "Namespace freed\n"));
718     return_VOID;
719 }
720 
721 
722 /*******************************************************************************
723  *
724  * FUNCTION:    AcpiNsOpensScope
725  *
726  * PARAMETERS:  Type        - A valid namespace type
727  *
728  * RETURN:      NEWSCOPE if the passed type "opens a name scope" according
729  *              to the ACPI specification, else 0
730  *
731  ******************************************************************************/
732 
733 UINT32
734 AcpiNsOpensScope (
735     ACPI_OBJECT_TYPE        Type)
736 {
737     ACPI_FUNCTION_ENTRY ();
738 
739 
740     if (Type > ACPI_TYPE_LOCAL_MAX)
741     {
742         /* type code out of range  */
743 
744         ACPI_WARNING ((AE_INFO, "Invalid Object Type 0x%X", Type));
745         return (ACPI_NS_NORMAL);
746     }
747 
748     return (((UINT32) AcpiGbl_NsProperties[Type]) & ACPI_NS_NEWSCOPE);
749 }
750 
751 
752 /*******************************************************************************
753  *
754  * FUNCTION:    AcpiNsGetNode
755  *
756  * PARAMETERS:  *Pathname   - Name to be found, in external (ASL) format. The
757  *                            \ (backslash) and ^ (carat) prefixes, and the
758  *                            . (period) to separate segments are supported.
759  *              PrefixNode   - Root of subtree to be searched, or NS_ALL for the
760  *                            root of the name space. If Name is fully
761  *                            qualified (first INT8 is '\'), the passed value
762  *                            of Scope will not be accessed.
763  *              Flags       - Used to indicate whether to perform upsearch or
764  *                            not.
765  *              ReturnNode  - Where the Node is returned
766  *
767  * DESCRIPTION: Look up a name relative to a given scope and return the
768  *              corresponding Node. NOTE: Scope can be null.
769  *
770  * MUTEX:       Locks namespace
771  *
772  ******************************************************************************/
773 
774 ACPI_STATUS
775 AcpiNsGetNode (
776     ACPI_NAMESPACE_NODE     *PrefixNode,
777     const char              *Pathname,
778     UINT32                  Flags,
779     ACPI_NAMESPACE_NODE     **ReturnNode)
780 {
781     ACPI_GENERIC_STATE      ScopeInfo;
782     ACPI_STATUS             Status;
783     char                    *InternalPath;
784 
785 
786     ACPI_FUNCTION_TRACE_PTR (NsGetNode, ACPI_CAST_PTR (char, Pathname));
787 
788 
789     /* Simplest case is a null pathname */
790 
791     if (!Pathname)
792     {
793         *ReturnNode = PrefixNode;
794         if (!PrefixNode)
795         {
796             *ReturnNode = AcpiGbl_RootNode;
797         }
798         return_ACPI_STATUS (AE_OK);
799     }
800 
801     /* Quick check for a reference to the root */
802 
803     if (ACPI_IS_ROOT_PREFIX (Pathname[0]) && (!Pathname[1]))
804     {
805         *ReturnNode = AcpiGbl_RootNode;
806         return_ACPI_STATUS (AE_OK);
807     }
808 
809     /* Convert path to internal representation */
810 
811     Status = AcpiNsInternalizeName (Pathname, &InternalPath);
812     if (ACPI_FAILURE (Status))
813     {
814         return_ACPI_STATUS (Status);
815     }
816 
817     /* Must lock namespace during lookup */
818 
819     Status = AcpiUtAcquireMutex (ACPI_MTX_NAMESPACE);
820     if (ACPI_FAILURE (Status))
821     {
822         goto Cleanup;
823     }
824 
825     /* Setup lookup scope (search starting point) */
826 
827     ScopeInfo.Scope.Node = PrefixNode;
828 
829     /* Lookup the name in the namespace */
830 
831     Status = AcpiNsLookup (&ScopeInfo, InternalPath, ACPI_TYPE_ANY,
832                 ACPI_IMODE_EXECUTE, (Flags | ACPI_NS_DONT_OPEN_SCOPE),
833                 NULL, ReturnNode);
834     if (ACPI_FAILURE (Status))
835     {
836         ACPI_DEBUG_PRINT ((ACPI_DB_EXEC, "%s, %s\n",
837                 Pathname, AcpiFormatException (Status)));
838     }
839 
840     (void) AcpiUtReleaseMutex (ACPI_MTX_NAMESPACE);
841 
842 Cleanup:
843     ACPI_FREE (InternalPath);
844     return_ACPI_STATUS (Status);
845 }
846