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1 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
2 /*******************************************************************************
3  *
4  * Module Name: rscalc - Calculate stream and list lengths
5  *
6  ******************************************************************************/
7 
8 #include <acpi/acpi.h>
9 #include "accommon.h"
10 #include "acresrc.h"
11 #include "acnamesp.h"
12 
13 #define _COMPONENT          ACPI_RESOURCES
14 ACPI_MODULE_NAME("rscalc")
15 
16 /* Local prototypes */
17 static u8 acpi_rs_count_set_bits(u16 bit_field);
18 
19 static acpi_rs_length
20 acpi_rs_struct_option_length(struct acpi_resource_source *resource_source);
21 
22 static u32
23 acpi_rs_stream_option_length(u32 resource_length, u32 minimum_total_length);
24 
25 /*******************************************************************************
26  *
27  * FUNCTION:    acpi_rs_count_set_bits
28  *
29  * PARAMETERS:  bit_field       - Field in which to count bits
30  *
31  * RETURN:      Number of bits set within the field
32  *
33  * DESCRIPTION: Count the number of bits set in a resource field. Used for
34  *              (Short descriptor) interrupt and DMA lists.
35  *
36  ******************************************************************************/
37 
acpi_rs_count_set_bits(u16 bit_field)38 static u8 acpi_rs_count_set_bits(u16 bit_field)
39 {
40 	u8 bits_set;
41 
42 	ACPI_FUNCTION_ENTRY();
43 
44 	for (bits_set = 0; bit_field; bits_set++) {
45 
46 		/* Zero the least significant bit that is set */
47 
48 		bit_field &= (u16) (bit_field - 1);
49 	}
50 
51 	return (bits_set);
52 }
53 
54 /*******************************************************************************
55  *
56  * FUNCTION:    acpi_rs_struct_option_length
57  *
58  * PARAMETERS:  resource_source     - Pointer to optional descriptor field
59  *
60  * RETURN:      Status
61  *
62  * DESCRIPTION: Common code to handle optional resource_source_index and
63  *              resource_source fields in some Large descriptors. Used during
64  *              list-to-stream conversion
65  *
66  ******************************************************************************/
67 
68 static acpi_rs_length
acpi_rs_struct_option_length(struct acpi_resource_source * resource_source)69 acpi_rs_struct_option_length(struct acpi_resource_source *resource_source)
70 {
71 	ACPI_FUNCTION_ENTRY();
72 
73 	/*
74 	 * If the resource_source string is valid, return the size of the string
75 	 * (string_length includes the NULL terminator) plus the size of the
76 	 * resource_source_index (1).
77 	 */
78 	if (resource_source->string_ptr) {
79 		return ((acpi_rs_length)(resource_source->string_length + 1));
80 	}
81 
82 	return (0);
83 }
84 
85 /*******************************************************************************
86  *
87  * FUNCTION:    acpi_rs_stream_option_length
88  *
89  * PARAMETERS:  resource_length     - Length from the resource header
90  *              minimum_total_length - Minimum length of this resource, before
91  *                                    any optional fields. Includes header size
92  *
93  * RETURN:      Length of optional string (0 if no string present)
94  *
95  * DESCRIPTION: Common code to handle optional resource_source_index and
96  *              resource_source fields in some Large descriptors. Used during
97  *              stream-to-list conversion
98  *
99  ******************************************************************************/
100 
101 static u32
acpi_rs_stream_option_length(u32 resource_length,u32 minimum_aml_resource_length)102 acpi_rs_stream_option_length(u32 resource_length,
103 			     u32 minimum_aml_resource_length)
104 {
105 	u32 string_length = 0;
106 
107 	ACPI_FUNCTION_ENTRY();
108 
109 	/*
110 	 * The resource_source_index and resource_source are optional elements of
111 	 * some Large-type resource descriptors.
112 	 */
113 
114 	/*
115 	 * If the length of the actual resource descriptor is greater than the
116 	 * ACPI spec-defined minimum length, it means that a resource_source_index
117 	 * exists and is followed by a (required) null terminated string. The
118 	 * string length (including the null terminator) is the resource length
119 	 * minus the minimum length, minus one byte for the resource_source_index
120 	 * itself.
121 	 */
122 	if (resource_length > minimum_aml_resource_length) {
123 
124 		/* Compute the length of the optional string */
125 
126 		string_length =
127 		    resource_length - minimum_aml_resource_length - 1;
128 	}
129 
130 	/*
131 	 * Round the length up to a multiple of the native word in order to
132 	 * guarantee that the entire resource descriptor is native word aligned
133 	 */
134 	return ((u32) ACPI_ROUND_UP_TO_NATIVE_WORD(string_length));
135 }
136 
137 /*******************************************************************************
138  *
139  * FUNCTION:    acpi_rs_get_aml_length
140  *
141  * PARAMETERS:  resource            - Pointer to the resource linked list
142  *              resource_list_size  - Size of the resource linked list
143  *              size_needed         - Where the required size is returned
144  *
145  * RETURN:      Status
146  *
147  * DESCRIPTION: Takes a linked list of internal resource descriptors and
148  *              calculates the size buffer needed to hold the corresponding
149  *              external resource byte stream.
150  *
151  ******************************************************************************/
152 
153 acpi_status
acpi_rs_get_aml_length(struct acpi_resource * resource,acpi_size resource_list_size,acpi_size * size_needed)154 acpi_rs_get_aml_length(struct acpi_resource *resource,
155 		       acpi_size resource_list_size, acpi_size *size_needed)
156 {
157 	acpi_size aml_size_needed = 0;
158 	struct acpi_resource *resource_end;
159 	acpi_rs_length total_size;
160 
161 	ACPI_FUNCTION_TRACE(rs_get_aml_length);
162 
163 	/* Traverse entire list of internal resource descriptors */
164 
165 	resource_end =
166 	    ACPI_ADD_PTR(struct acpi_resource, resource, resource_list_size);
167 	while (resource < resource_end) {
168 
169 		/* Validate the descriptor type */
170 
171 		if (resource->type > ACPI_RESOURCE_TYPE_MAX) {
172 			return_ACPI_STATUS(AE_AML_INVALID_RESOURCE_TYPE);
173 		}
174 
175 		/* Sanity check the length. It must not be zero, or we loop forever */
176 
177 		if (!resource->length) {
178 			return_ACPI_STATUS(AE_AML_BAD_RESOURCE_LENGTH);
179 		}
180 
181 		/* Get the base size of the (external stream) resource descriptor */
182 
183 		total_size = acpi_gbl_aml_resource_sizes[resource->type];
184 
185 		/*
186 		 * Augment the base size for descriptors with optional and/or
187 		 * variable-length fields
188 		 */
189 		switch (resource->type) {
190 		case ACPI_RESOURCE_TYPE_IRQ:
191 
192 			/* Length can be 3 or 2 */
193 
194 			if (resource->data.irq.descriptor_length == 2) {
195 				total_size--;
196 			}
197 			break;
198 
199 		case ACPI_RESOURCE_TYPE_START_DEPENDENT:
200 
201 			/* Length can be 1 or 0 */
202 
203 			if (resource->data.irq.descriptor_length == 0) {
204 				total_size--;
205 			}
206 			break;
207 
208 		case ACPI_RESOURCE_TYPE_VENDOR:
209 			/*
210 			 * Vendor Defined Resource:
211 			 * For a Vendor Specific resource, if the Length is between 1 and 7
212 			 * it will be created as a Small Resource data type, otherwise it
213 			 * is a Large Resource data type.
214 			 */
215 			if (resource->data.vendor.byte_length > 7) {
216 
217 				/* Base size of a Large resource descriptor */
218 
219 				total_size =
220 				    sizeof(struct aml_resource_large_header);
221 			}
222 
223 			/* Add the size of the vendor-specific data */
224 
225 			total_size = (acpi_rs_length)
226 			    (total_size + resource->data.vendor.byte_length);
227 			break;
228 
229 		case ACPI_RESOURCE_TYPE_END_TAG:
230 			/*
231 			 * End Tag:
232 			 * We are done -- return the accumulated total size.
233 			 */
234 			*size_needed = aml_size_needed + total_size;
235 
236 			/* Normal exit */
237 
238 			return_ACPI_STATUS(AE_OK);
239 
240 		case ACPI_RESOURCE_TYPE_ADDRESS16:
241 			/*
242 			 * 16-Bit Address Resource:
243 			 * Add the size of the optional resource_source info
244 			 */
245 			total_size = (acpi_rs_length)(total_size +
246 						      acpi_rs_struct_option_length
247 						      (&resource->data.
248 						       address16.
249 						       resource_source));
250 			break;
251 
252 		case ACPI_RESOURCE_TYPE_ADDRESS32:
253 			/*
254 			 * 32-Bit Address Resource:
255 			 * Add the size of the optional resource_source info
256 			 */
257 			total_size = (acpi_rs_length)(total_size +
258 						      acpi_rs_struct_option_length
259 						      (&resource->data.
260 						       address32.
261 						       resource_source));
262 			break;
263 
264 		case ACPI_RESOURCE_TYPE_ADDRESS64:
265 			/*
266 			 * 64-Bit Address Resource:
267 			 * Add the size of the optional resource_source info
268 			 */
269 			total_size = (acpi_rs_length)(total_size +
270 						      acpi_rs_struct_option_length
271 						      (&resource->data.
272 						       address64.
273 						       resource_source));
274 			break;
275 
276 		case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
277 			/*
278 			 * Extended IRQ Resource:
279 			 * Add the size of each additional optional interrupt beyond the
280 			 * required 1 (4 bytes for each u32 interrupt number)
281 			 */
282 			total_size = (acpi_rs_length)(total_size +
283 						      ((resource->data.
284 							extended_irq.
285 							interrupt_count -
286 							1) * 4) +
287 						      /* Add the size of the optional resource_source info */
288 						      acpi_rs_struct_option_length
289 						      (&resource->data.
290 						       extended_irq.
291 						       resource_source));
292 			break;
293 
294 		case ACPI_RESOURCE_TYPE_GPIO:
295 
296 			total_size = (acpi_rs_length)(total_size +
297 						      (resource->data.gpio.
298 						       pin_table_length * 2) +
299 						      resource->data.gpio.
300 						      resource_source.
301 						      string_length +
302 						      resource->data.gpio.
303 						      vendor_length);
304 
305 			break;
306 
307 		case ACPI_RESOURCE_TYPE_PIN_FUNCTION:
308 
309 			total_size = (acpi_rs_length)(total_size +
310 						      (resource->data.
311 						       pin_function.
312 						       pin_table_length * 2) +
313 						      resource->data.
314 						      pin_function.
315 						      resource_source.
316 						      string_length +
317 						      resource->data.
318 						      pin_function.
319 						      vendor_length);
320 
321 			break;
322 
323 		case ACPI_RESOURCE_TYPE_SERIAL_BUS:
324 
325 			total_size =
326 			    acpi_gbl_aml_resource_serial_bus_sizes[resource->
327 								   data.
328 								   common_serial_bus.
329 								   type];
330 
331 			total_size = (acpi_rs_length)(total_size +
332 						      resource->data.
333 						      i2c_serial_bus.
334 						      resource_source.
335 						      string_length +
336 						      resource->data.
337 						      i2c_serial_bus.
338 						      vendor_length);
339 
340 			break;
341 
342 		case ACPI_RESOURCE_TYPE_PIN_CONFIG:
343 
344 			total_size = (acpi_rs_length)(total_size +
345 						      (resource->data.
346 						       pin_config.
347 						       pin_table_length * 2) +
348 						      resource->data.pin_config.
349 						      resource_source.
350 						      string_length +
351 						      resource->data.pin_config.
352 						      vendor_length);
353 
354 			break;
355 
356 		case ACPI_RESOURCE_TYPE_PIN_GROUP:
357 
358 			total_size = (acpi_rs_length)(total_size +
359 						      (resource->data.pin_group.
360 						       pin_table_length * 2) +
361 						      resource->data.pin_group.
362 						      resource_label.
363 						      string_length +
364 						      resource->data.pin_group.
365 						      vendor_length);
366 
367 			break;
368 
369 		case ACPI_RESOURCE_TYPE_PIN_GROUP_FUNCTION:
370 
371 			total_size = (acpi_rs_length)(total_size +
372 						      resource->data.
373 						      pin_group_function.
374 						      resource_source.
375 						      string_length +
376 						      resource->data.
377 						      pin_group_function.
378 						      resource_source_label.
379 						      string_length +
380 						      resource->data.
381 						      pin_group_function.
382 						      vendor_length);
383 
384 			break;
385 
386 		case ACPI_RESOURCE_TYPE_PIN_GROUP_CONFIG:
387 
388 			total_size = (acpi_rs_length)(total_size +
389 						      resource->data.
390 						      pin_group_config.
391 						      resource_source.
392 						      string_length +
393 						      resource->data.
394 						      pin_group_config.
395 						      resource_source_label.
396 						      string_length +
397 						      resource->data.
398 						      pin_group_config.
399 						      vendor_length);
400 
401 			break;
402 
403 		default:
404 
405 			break;
406 		}
407 
408 		/* Update the total */
409 
410 		aml_size_needed += total_size;
411 
412 		/* Point to the next object */
413 
414 		resource =
415 		    ACPI_ADD_PTR(struct acpi_resource, resource,
416 				 resource->length);
417 	}
418 
419 	/* Did not find an end_tag resource descriptor */
420 
421 	return_ACPI_STATUS(AE_AML_NO_RESOURCE_END_TAG);
422 }
423 
424 /*******************************************************************************
425  *
426  * FUNCTION:    acpi_rs_get_list_length
427  *
428  * PARAMETERS:  aml_buffer          - Pointer to the resource byte stream
429  *              aml_buffer_length   - Size of aml_buffer
430  *              size_needed         - Where the size needed is returned
431  *
432  * RETURN:      Status
433  *
434  * DESCRIPTION: Takes an external resource byte stream and calculates the size
435  *              buffer needed to hold the corresponding internal resource
436  *              descriptor linked list.
437  *
438  ******************************************************************************/
439 
440 acpi_status
acpi_rs_get_list_length(u8 * aml_buffer,u32 aml_buffer_length,acpi_size * size_needed)441 acpi_rs_get_list_length(u8 *aml_buffer,
442 			u32 aml_buffer_length, acpi_size *size_needed)
443 {
444 	acpi_status status;
445 	u8 *end_aml;
446 	u8 *buffer;
447 	u32 buffer_size;
448 	u16 temp16;
449 	u16 resource_length;
450 	u32 extra_struct_bytes;
451 	u8 resource_index;
452 	u8 minimum_aml_resource_length;
453 	union aml_resource *aml_resource;
454 
455 	ACPI_FUNCTION_TRACE(rs_get_list_length);
456 
457 	*size_needed = ACPI_RS_SIZE_MIN;	/* Minimum size is one end_tag */
458 	end_aml = aml_buffer + aml_buffer_length;
459 
460 	/* Walk the list of AML resource descriptors */
461 
462 	while (aml_buffer < end_aml) {
463 
464 		/* Validate the Resource Type and Resource Length */
465 
466 		status =
467 		    acpi_ut_validate_resource(NULL, aml_buffer,
468 					      &resource_index);
469 		if (ACPI_FAILURE(status)) {
470 			/*
471 			 * Exit on failure. Cannot continue because the descriptor length
472 			 * may be bogus also.
473 			 */
474 			return_ACPI_STATUS(status);
475 		}
476 
477 		aml_resource = (void *)aml_buffer;
478 
479 		/* Get the resource length and base (minimum) AML size */
480 
481 		resource_length = acpi_ut_get_resource_length(aml_buffer);
482 		minimum_aml_resource_length =
483 		    acpi_gbl_resource_aml_sizes[resource_index];
484 
485 		/*
486 		 * Augment the size for descriptors with optional
487 		 * and/or variable length fields
488 		 */
489 		extra_struct_bytes = 0;
490 		buffer =
491 		    aml_buffer + acpi_ut_get_resource_header_length(aml_buffer);
492 
493 		switch (acpi_ut_get_resource_type(aml_buffer)) {
494 		case ACPI_RESOURCE_NAME_IRQ:
495 			/*
496 			 * IRQ Resource:
497 			 * Get the number of bits set in the 16-bit IRQ mask
498 			 */
499 			ACPI_MOVE_16_TO_16(&temp16, buffer);
500 			extra_struct_bytes = acpi_rs_count_set_bits(temp16);
501 			break;
502 
503 		case ACPI_RESOURCE_NAME_DMA:
504 			/*
505 			 * DMA Resource:
506 			 * Get the number of bits set in the 8-bit DMA mask
507 			 */
508 			extra_struct_bytes = acpi_rs_count_set_bits(*buffer);
509 			break;
510 
511 		case ACPI_RESOURCE_NAME_VENDOR_SMALL:
512 		case ACPI_RESOURCE_NAME_VENDOR_LARGE:
513 			/*
514 			 * Vendor Resource:
515 			 * Get the number of vendor data bytes
516 			 */
517 			extra_struct_bytes = resource_length;
518 
519 			/*
520 			 * There is already one byte included in the minimum
521 			 * descriptor size. If there are extra struct bytes,
522 			 * subtract one from the count.
523 			 */
524 			if (extra_struct_bytes) {
525 				extra_struct_bytes--;
526 			}
527 			break;
528 
529 		case ACPI_RESOURCE_NAME_END_TAG:
530 			/*
531 			 * End Tag: This is the normal exit
532 			 */
533 			return_ACPI_STATUS(AE_OK);
534 
535 		case ACPI_RESOURCE_NAME_ADDRESS32:
536 		case ACPI_RESOURCE_NAME_ADDRESS16:
537 		case ACPI_RESOURCE_NAME_ADDRESS64:
538 			/*
539 			 * Address Resource:
540 			 * Add the size of the optional resource_source
541 			 */
542 			extra_struct_bytes =
543 			    acpi_rs_stream_option_length(resource_length,
544 							 minimum_aml_resource_length);
545 			break;
546 
547 		case ACPI_RESOURCE_NAME_EXTENDED_IRQ:
548 			/*
549 			 * Extended IRQ Resource:
550 			 * Using the interrupt_table_length, add 4 bytes for each additional
551 			 * interrupt. Note: at least one interrupt is required and is
552 			 * included in the minimum descriptor size (reason for the -1)
553 			 */
554 			extra_struct_bytes = (buffer[1] - 1) * sizeof(u32);
555 
556 			/* Add the size of the optional resource_source */
557 
558 			extra_struct_bytes +=
559 			    acpi_rs_stream_option_length(resource_length -
560 							 extra_struct_bytes,
561 							 minimum_aml_resource_length);
562 			break;
563 
564 		case ACPI_RESOURCE_NAME_GPIO:
565 
566 			/* Vendor data is optional */
567 
568 			if (aml_resource->gpio.vendor_length) {
569 				extra_struct_bytes +=
570 				    aml_resource->gpio.vendor_offset -
571 				    aml_resource->gpio.pin_table_offset +
572 				    aml_resource->gpio.vendor_length;
573 			} else {
574 				extra_struct_bytes +=
575 				    aml_resource->large_header.resource_length +
576 				    sizeof(struct aml_resource_large_header) -
577 				    aml_resource->gpio.pin_table_offset;
578 			}
579 			break;
580 
581 		case ACPI_RESOURCE_NAME_PIN_FUNCTION:
582 
583 			/* Vendor data is optional */
584 
585 			if (aml_resource->pin_function.vendor_length) {
586 				extra_struct_bytes +=
587 				    aml_resource->pin_function.vendor_offset -
588 				    aml_resource->pin_function.
589 				    pin_table_offset +
590 				    aml_resource->pin_function.vendor_length;
591 			} else {
592 				extra_struct_bytes +=
593 				    aml_resource->large_header.resource_length +
594 				    sizeof(struct aml_resource_large_header) -
595 				    aml_resource->pin_function.pin_table_offset;
596 			}
597 			break;
598 
599 		case ACPI_RESOURCE_NAME_SERIAL_BUS:
600 
601 			minimum_aml_resource_length =
602 			    acpi_gbl_resource_aml_serial_bus_sizes
603 			    [aml_resource->common_serial_bus.type];
604 			extra_struct_bytes +=
605 			    aml_resource->common_serial_bus.resource_length -
606 			    minimum_aml_resource_length;
607 			break;
608 
609 		case ACPI_RESOURCE_NAME_PIN_CONFIG:
610 
611 			/* Vendor data is optional */
612 
613 			if (aml_resource->pin_config.vendor_length) {
614 				extra_struct_bytes +=
615 				    aml_resource->pin_config.vendor_offset -
616 				    aml_resource->pin_config.pin_table_offset +
617 				    aml_resource->pin_config.vendor_length;
618 			} else {
619 				extra_struct_bytes +=
620 				    aml_resource->large_header.resource_length +
621 				    sizeof(struct aml_resource_large_header) -
622 				    aml_resource->pin_config.pin_table_offset;
623 			}
624 			break;
625 
626 		case ACPI_RESOURCE_NAME_PIN_GROUP:
627 
628 			extra_struct_bytes +=
629 			    aml_resource->pin_group.vendor_offset -
630 			    aml_resource->pin_group.pin_table_offset +
631 			    aml_resource->pin_group.vendor_length;
632 
633 			break;
634 
635 		case ACPI_RESOURCE_NAME_PIN_GROUP_FUNCTION:
636 
637 			extra_struct_bytes +=
638 			    aml_resource->pin_group_function.vendor_offset -
639 			    aml_resource->pin_group_function.res_source_offset +
640 			    aml_resource->pin_group_function.vendor_length;
641 
642 			break;
643 
644 		case ACPI_RESOURCE_NAME_PIN_GROUP_CONFIG:
645 
646 			extra_struct_bytes +=
647 			    aml_resource->pin_group_config.vendor_offset -
648 			    aml_resource->pin_group_config.res_source_offset +
649 			    aml_resource->pin_group_config.vendor_length;
650 
651 			break;
652 
653 		default:
654 
655 			break;
656 		}
657 
658 		/*
659 		 * Update the required buffer size for the internal descriptor structs
660 		 *
661 		 * Important: Round the size up for the appropriate alignment. This
662 		 * is a requirement on IA64.
663 		 */
664 		if (acpi_ut_get_resource_type(aml_buffer) ==
665 		    ACPI_RESOURCE_NAME_SERIAL_BUS) {
666 			buffer_size =
667 			    acpi_gbl_resource_struct_serial_bus_sizes
668 			    [aml_resource->common_serial_bus.type] +
669 			    extra_struct_bytes;
670 		} else {
671 			buffer_size =
672 			    acpi_gbl_resource_struct_sizes[resource_index] +
673 			    extra_struct_bytes;
674 		}
675 
676 		buffer_size = (u32)ACPI_ROUND_UP_TO_NATIVE_WORD(buffer_size);
677 		*size_needed += buffer_size;
678 
679 		ACPI_DEBUG_PRINT((ACPI_DB_RESOURCES,
680 				  "Type %.2X, AmlLength %.2X InternalLength %.2X\n",
681 				  acpi_ut_get_resource_type(aml_buffer),
682 				  acpi_ut_get_descriptor_length(aml_buffer),
683 				  buffer_size));
684 
685 		/*
686 		 * Point to the next resource within the AML stream using the length
687 		 * contained in the resource descriptor header
688 		 */
689 		aml_buffer += acpi_ut_get_descriptor_length(aml_buffer);
690 	}
691 
692 	/* Did not find an end_tag resource descriptor */
693 
694 	return_ACPI_STATUS(AE_AML_NO_RESOURCE_END_TAG);
695 }
696 
697 /*******************************************************************************
698  *
699  * FUNCTION:    acpi_rs_get_pci_routing_table_length
700  *
701  * PARAMETERS:  package_object          - Pointer to the package object
702  *              buffer_size_needed      - u32 pointer of the size buffer
703  *                                        needed to properly return the
704  *                                        parsed data
705  *
706  * RETURN:      Status
707  *
708  * DESCRIPTION: Given a package representing a PCI routing table, this
709  *              calculates the size of the corresponding linked list of
710  *              descriptions.
711  *
712  ******************************************************************************/
713 
714 acpi_status
acpi_rs_get_pci_routing_table_length(union acpi_operand_object * package_object,acpi_size * buffer_size_needed)715 acpi_rs_get_pci_routing_table_length(union acpi_operand_object *package_object,
716 				     acpi_size *buffer_size_needed)
717 {
718 	u32 number_of_elements;
719 	acpi_size temp_size_needed = 0;
720 	union acpi_operand_object **top_object_list;
721 	u32 index;
722 	union acpi_operand_object *package_element;
723 	union acpi_operand_object **sub_object_list;
724 	u8 name_found;
725 	u32 table_index;
726 
727 	ACPI_FUNCTION_TRACE(rs_get_pci_routing_table_length);
728 
729 	number_of_elements = package_object->package.count;
730 
731 	/*
732 	 * Calculate the size of the return buffer.
733 	 * The base size is the number of elements * the sizes of the
734 	 * structures. Additional space for the strings is added below.
735 	 * The minus one is to subtract the size of the u8 Source[1]
736 	 * member because it is added below.
737 	 *
738 	 * But each PRT_ENTRY structure has a pointer to a string and
739 	 * the size of that string must be found.
740 	 */
741 	top_object_list = package_object->package.elements;
742 
743 	for (index = 0; index < number_of_elements; index++) {
744 
745 		/* Dereference the subpackage */
746 
747 		package_element = *top_object_list;
748 
749 		/* We must have a valid Package object */
750 
751 		if (!package_element ||
752 		    (package_element->common.type != ACPI_TYPE_PACKAGE)) {
753 			return_ACPI_STATUS(AE_AML_OPERAND_TYPE);
754 		}
755 
756 		/*
757 		 * The sub_object_list will now point to an array of the
758 		 * four IRQ elements: Address, Pin, Source and source_index
759 		 */
760 		sub_object_list = package_element->package.elements;
761 
762 		/* Scan the irq_table_elements for the Source Name String */
763 
764 		name_found = FALSE;
765 
766 		for (table_index = 0;
767 		     table_index < package_element->package.count
768 		     && !name_found; table_index++) {
769 			if (*sub_object_list &&	/* Null object allowed */
770 			    ((ACPI_TYPE_STRING ==
771 			      (*sub_object_list)->common.type) ||
772 			     ((ACPI_TYPE_LOCAL_REFERENCE ==
773 			       (*sub_object_list)->common.type) &&
774 			      ((*sub_object_list)->reference.class ==
775 			       ACPI_REFCLASS_NAME)))) {
776 				name_found = TRUE;
777 			} else {
778 				/* Look at the next element */
779 
780 				sub_object_list++;
781 			}
782 		}
783 
784 		temp_size_needed += (sizeof(struct acpi_pci_routing_table) - 4);
785 
786 		/* Was a String type found? */
787 
788 		if (name_found) {
789 			if ((*sub_object_list)->common.type == ACPI_TYPE_STRING) {
790 				/*
791 				 * The length String.Length field does not include the
792 				 * terminating NULL, add 1
793 				 */
794 				temp_size_needed += ((acpi_size)
795 						     (*sub_object_list)->string.
796 						     length + 1);
797 			} else {
798 				temp_size_needed += acpi_ns_get_pathname_length((*sub_object_list)->reference.node);
799 			}
800 		} else {
801 			/*
802 			 * If no name was found, then this is a NULL, which is
803 			 * translated as a u32 zero.
804 			 */
805 			temp_size_needed += sizeof(u32);
806 		}
807 
808 		/* Round up the size since each element must be aligned */
809 
810 		temp_size_needed = ACPI_ROUND_UP_TO_64BIT(temp_size_needed);
811 
812 		/* Point to the next union acpi_operand_object */
813 
814 		top_object_list++;
815 	}
816 
817 	/*
818 	 * Add an extra element to the end of the list, essentially a
819 	 * NULL terminator
820 	 */
821 	*buffer_size_needed =
822 	    temp_size_needed + sizeof(struct acpi_pci_routing_table);
823 	return_ACPI_STATUS(AE_OK);
824 }
825