xref: /openbmc/linux/drivers/acpi/acpica/rscalc.c (revision 703e7713)
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 
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
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
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
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_CLOCK_INPUT:
324 
325 			total_size = (acpi_rs_length)(total_size +
326 						      resource->data.
327 						      clock_input.
328 						      resource_source.
329 						      string_length);
330 
331 			break;
332 
333 		case ACPI_RESOURCE_TYPE_SERIAL_BUS:
334 
335 			total_size =
336 			    acpi_gbl_aml_resource_serial_bus_sizes[resource->
337 								   data.
338 								   common_serial_bus.
339 								   type];
340 
341 			total_size = (acpi_rs_length)(total_size +
342 						      resource->data.
343 						      i2c_serial_bus.
344 						      resource_source.
345 						      string_length +
346 						      resource->data.
347 						      i2c_serial_bus.
348 						      vendor_length);
349 
350 			break;
351 
352 		case ACPI_RESOURCE_TYPE_PIN_CONFIG:
353 
354 			total_size = (acpi_rs_length)(total_size +
355 						      (resource->data.
356 						       pin_config.
357 						       pin_table_length * 2) +
358 						      resource->data.pin_config.
359 						      resource_source.
360 						      string_length +
361 						      resource->data.pin_config.
362 						      vendor_length);
363 
364 			break;
365 
366 		case ACPI_RESOURCE_TYPE_PIN_GROUP:
367 
368 			total_size = (acpi_rs_length)(total_size +
369 						      (resource->data.pin_group.
370 						       pin_table_length * 2) +
371 						      resource->data.pin_group.
372 						      resource_label.
373 						      string_length +
374 						      resource->data.pin_group.
375 						      vendor_length);
376 
377 			break;
378 
379 		case ACPI_RESOURCE_TYPE_PIN_GROUP_FUNCTION:
380 
381 			total_size = (acpi_rs_length)(total_size +
382 						      resource->data.
383 						      pin_group_function.
384 						      resource_source.
385 						      string_length +
386 						      resource->data.
387 						      pin_group_function.
388 						      resource_source_label.
389 						      string_length +
390 						      resource->data.
391 						      pin_group_function.
392 						      vendor_length);
393 
394 			break;
395 
396 		case ACPI_RESOURCE_TYPE_PIN_GROUP_CONFIG:
397 
398 			total_size = (acpi_rs_length)(total_size +
399 						      resource->data.
400 						      pin_group_config.
401 						      resource_source.
402 						      string_length +
403 						      resource->data.
404 						      pin_group_config.
405 						      resource_source_label.
406 						      string_length +
407 						      resource->data.
408 						      pin_group_config.
409 						      vendor_length);
410 
411 			break;
412 
413 		default:
414 
415 			break;
416 		}
417 
418 		/* Update the total */
419 
420 		aml_size_needed += total_size;
421 
422 		/* Point to the next object */
423 
424 		resource =
425 		    ACPI_ADD_PTR(struct acpi_resource, resource,
426 				 resource->length);
427 	}
428 
429 	/* Did not find an end_tag resource descriptor */
430 
431 	return_ACPI_STATUS(AE_AML_NO_RESOURCE_END_TAG);
432 }
433 
434 /*******************************************************************************
435  *
436  * FUNCTION:    acpi_rs_get_list_length
437  *
438  * PARAMETERS:  aml_buffer          - Pointer to the resource byte stream
439  *              aml_buffer_length   - Size of aml_buffer
440  *              size_needed         - Where the size needed is returned
441  *
442  * RETURN:      Status
443  *
444  * DESCRIPTION: Takes an external resource byte stream and calculates the size
445  *              buffer needed to hold the corresponding internal resource
446  *              descriptor linked list.
447  *
448  ******************************************************************************/
449 
450 acpi_status
451 acpi_rs_get_list_length(u8 *aml_buffer,
452 			u32 aml_buffer_length, acpi_size *size_needed)
453 {
454 	acpi_status status;
455 	u8 *end_aml;
456 	u8 *buffer;
457 	u32 buffer_size;
458 	u16 temp16;
459 	u16 resource_length;
460 	u32 extra_struct_bytes;
461 	u8 resource_index;
462 	u8 minimum_aml_resource_length;
463 	union aml_resource *aml_resource;
464 
465 	ACPI_FUNCTION_TRACE(rs_get_list_length);
466 
467 	*size_needed = ACPI_RS_SIZE_MIN;	/* Minimum size is one end_tag */
468 	end_aml = aml_buffer + aml_buffer_length;
469 
470 	/* Walk the list of AML resource descriptors */
471 
472 	while (aml_buffer < end_aml) {
473 
474 		/* Validate the Resource Type and Resource Length */
475 
476 		status =
477 		    acpi_ut_validate_resource(NULL, aml_buffer,
478 					      &resource_index);
479 		if (ACPI_FAILURE(status)) {
480 			/*
481 			 * Exit on failure. Cannot continue because the descriptor length
482 			 * may be bogus also.
483 			 */
484 			return_ACPI_STATUS(status);
485 		}
486 
487 		aml_resource = (void *)aml_buffer;
488 
489 		/* Get the resource length and base (minimum) AML size */
490 
491 		resource_length = acpi_ut_get_resource_length(aml_buffer);
492 		minimum_aml_resource_length =
493 		    acpi_gbl_resource_aml_sizes[resource_index];
494 
495 		/*
496 		 * Augment the size for descriptors with optional
497 		 * and/or variable length fields
498 		 */
499 		extra_struct_bytes = 0;
500 		buffer =
501 		    aml_buffer + acpi_ut_get_resource_header_length(aml_buffer);
502 
503 		switch (acpi_ut_get_resource_type(aml_buffer)) {
504 		case ACPI_RESOURCE_NAME_IRQ:
505 			/*
506 			 * IRQ Resource:
507 			 * Get the number of bits set in the 16-bit IRQ mask
508 			 */
509 			ACPI_MOVE_16_TO_16(&temp16, buffer);
510 			extra_struct_bytes = acpi_rs_count_set_bits(temp16);
511 			break;
512 
513 		case ACPI_RESOURCE_NAME_DMA:
514 			/*
515 			 * DMA Resource:
516 			 * Get the number of bits set in the 8-bit DMA mask
517 			 */
518 			extra_struct_bytes = acpi_rs_count_set_bits(*buffer);
519 			break;
520 
521 		case ACPI_RESOURCE_NAME_VENDOR_SMALL:
522 		case ACPI_RESOURCE_NAME_VENDOR_LARGE:
523 			/*
524 			 * Vendor Resource:
525 			 * Get the number of vendor data bytes
526 			 */
527 			extra_struct_bytes = resource_length;
528 
529 			/*
530 			 * There is already one byte included in the minimum
531 			 * descriptor size. If there are extra struct bytes,
532 			 * subtract one from the count.
533 			 */
534 			if (extra_struct_bytes) {
535 				extra_struct_bytes--;
536 			}
537 			break;
538 
539 		case ACPI_RESOURCE_NAME_END_TAG:
540 			/*
541 			 * End Tag: This is the normal exit
542 			 */
543 			return_ACPI_STATUS(AE_OK);
544 
545 		case ACPI_RESOURCE_NAME_ADDRESS32:
546 		case ACPI_RESOURCE_NAME_ADDRESS16:
547 		case ACPI_RESOURCE_NAME_ADDRESS64:
548 			/*
549 			 * Address Resource:
550 			 * Add the size of the optional resource_source
551 			 */
552 			extra_struct_bytes =
553 			    acpi_rs_stream_option_length(resource_length,
554 							 minimum_aml_resource_length);
555 			break;
556 
557 		case ACPI_RESOURCE_NAME_EXTENDED_IRQ:
558 			/*
559 			 * Extended IRQ Resource:
560 			 * Using the interrupt_table_length, add 4 bytes for each additional
561 			 * interrupt. Note: at least one interrupt is required and is
562 			 * included in the minimum descriptor size (reason for the -1)
563 			 */
564 			extra_struct_bytes = (buffer[1] - 1) * sizeof(u32);
565 
566 			/* Add the size of the optional resource_source */
567 
568 			extra_struct_bytes +=
569 			    acpi_rs_stream_option_length(resource_length -
570 							 extra_struct_bytes,
571 							 minimum_aml_resource_length);
572 			break;
573 
574 		case ACPI_RESOURCE_NAME_GPIO:
575 
576 			/* Vendor data is optional */
577 
578 			if (aml_resource->gpio.vendor_length) {
579 				extra_struct_bytes +=
580 				    aml_resource->gpio.vendor_offset -
581 				    aml_resource->gpio.pin_table_offset +
582 				    aml_resource->gpio.vendor_length;
583 			} else {
584 				extra_struct_bytes +=
585 				    aml_resource->large_header.resource_length +
586 				    sizeof(struct aml_resource_large_header) -
587 				    aml_resource->gpio.pin_table_offset;
588 			}
589 			break;
590 
591 		case ACPI_RESOURCE_NAME_PIN_FUNCTION:
592 
593 			/* Vendor data is optional */
594 
595 			if (aml_resource->pin_function.vendor_length) {
596 				extra_struct_bytes +=
597 				    aml_resource->pin_function.vendor_offset -
598 				    aml_resource->pin_function.
599 				    pin_table_offset +
600 				    aml_resource->pin_function.vendor_length;
601 			} else {
602 				extra_struct_bytes +=
603 				    aml_resource->large_header.resource_length +
604 				    sizeof(struct aml_resource_large_header) -
605 				    aml_resource->pin_function.pin_table_offset;
606 			}
607 			break;
608 
609 		case ACPI_RESOURCE_NAME_SERIAL_BUS:{
610 
611 				/* Avoid undefined behavior: member access within misaligned address */
612 
613 				struct aml_resource_common_serialbus
614 				    common_serial_bus;
615 				memcpy(&common_serial_bus, aml_resource,
616 				       sizeof(common_serial_bus));
617 
618 				minimum_aml_resource_length =
619 				    acpi_gbl_resource_aml_serial_bus_sizes
620 				    [common_serial_bus.type];
621 				extra_struct_bytes +=
622 				    common_serial_bus.resource_length -
623 				    minimum_aml_resource_length;
624 				break;
625 			}
626 
627 		case ACPI_RESOURCE_NAME_PIN_CONFIG:
628 
629 			/* Vendor data is optional */
630 
631 			if (aml_resource->pin_config.vendor_length) {
632 				extra_struct_bytes +=
633 				    aml_resource->pin_config.vendor_offset -
634 				    aml_resource->pin_config.pin_table_offset +
635 				    aml_resource->pin_config.vendor_length;
636 			} else {
637 				extra_struct_bytes +=
638 				    aml_resource->large_header.resource_length +
639 				    sizeof(struct aml_resource_large_header) -
640 				    aml_resource->pin_config.pin_table_offset;
641 			}
642 			break;
643 
644 		case ACPI_RESOURCE_NAME_PIN_GROUP:
645 
646 			extra_struct_bytes +=
647 			    aml_resource->pin_group.vendor_offset -
648 			    aml_resource->pin_group.pin_table_offset +
649 			    aml_resource->pin_group.vendor_length;
650 
651 			break;
652 
653 		case ACPI_RESOURCE_NAME_PIN_GROUP_FUNCTION:
654 
655 			extra_struct_bytes +=
656 			    aml_resource->pin_group_function.vendor_offset -
657 			    aml_resource->pin_group_function.res_source_offset +
658 			    aml_resource->pin_group_function.vendor_length;
659 
660 			break;
661 
662 		case ACPI_RESOURCE_NAME_PIN_GROUP_CONFIG:
663 
664 			extra_struct_bytes +=
665 			    aml_resource->pin_group_config.vendor_offset -
666 			    aml_resource->pin_group_config.res_source_offset +
667 			    aml_resource->pin_group_config.vendor_length;
668 
669 			break;
670 
671 		case ACPI_RESOURCE_NAME_CLOCK_INPUT:
672 			extra_struct_bytes =
673 			    acpi_rs_stream_option_length(resource_length,
674 							 minimum_aml_resource_length);
675 
676 			break;
677 
678 		default:
679 
680 			break;
681 		}
682 
683 		/*
684 		 * Update the required buffer size for the internal descriptor structs
685 		 *
686 		 * Important: Round the size up for the appropriate alignment. This
687 		 * is a requirement on IA64.
688 		 */
689 		if (acpi_ut_get_resource_type(aml_buffer) ==
690 		    ACPI_RESOURCE_NAME_SERIAL_BUS) {
691 
692 			/* Avoid undefined behavior: member access within misaligned address */
693 
694 			struct aml_resource_common_serialbus common_serial_bus;
695 			memcpy(&common_serial_bus, aml_resource,
696 			       sizeof(common_serial_bus));
697 
698 			buffer_size =
699 			    acpi_gbl_resource_struct_serial_bus_sizes
700 			    [common_serial_bus.type] + extra_struct_bytes;
701 		} else {
702 			buffer_size =
703 			    acpi_gbl_resource_struct_sizes[resource_index] +
704 			    extra_struct_bytes;
705 		}
706 
707 		buffer_size = (u32)ACPI_ROUND_UP_TO_NATIVE_WORD(buffer_size);
708 		*size_needed += buffer_size;
709 
710 		ACPI_DEBUG_PRINT((ACPI_DB_RESOURCES,
711 				  "Type %.2X, AmlLength %.2X InternalLength %.2X%8X\n",
712 				  acpi_ut_get_resource_type(aml_buffer),
713 				  acpi_ut_get_descriptor_length(aml_buffer),
714 				  ACPI_FORMAT_UINT64(*size_needed)));
715 
716 		/*
717 		 * Point to the next resource within the AML stream using the length
718 		 * contained in the resource descriptor header
719 		 */
720 		aml_buffer += acpi_ut_get_descriptor_length(aml_buffer);
721 	}
722 
723 	/* Did not find an end_tag resource descriptor */
724 
725 	return_ACPI_STATUS(AE_AML_NO_RESOURCE_END_TAG);
726 }
727 
728 /*******************************************************************************
729  *
730  * FUNCTION:    acpi_rs_get_pci_routing_table_length
731  *
732  * PARAMETERS:  package_object          - Pointer to the package object
733  *              buffer_size_needed      - u32 pointer of the size buffer
734  *                                        needed to properly return the
735  *                                        parsed data
736  *
737  * RETURN:      Status
738  *
739  * DESCRIPTION: Given a package representing a PCI routing table, this
740  *              calculates the size of the corresponding linked list of
741  *              descriptions.
742  *
743  ******************************************************************************/
744 
745 acpi_status
746 acpi_rs_get_pci_routing_table_length(union acpi_operand_object *package_object,
747 				     acpi_size *buffer_size_needed)
748 {
749 	u32 number_of_elements;
750 	acpi_size temp_size_needed = 0;
751 	union acpi_operand_object **top_object_list;
752 	u32 index;
753 	union acpi_operand_object *package_element;
754 	union acpi_operand_object **sub_object_list;
755 	u8 name_found;
756 	u32 table_index;
757 
758 	ACPI_FUNCTION_TRACE(rs_get_pci_routing_table_length);
759 
760 	number_of_elements = package_object->package.count;
761 
762 	/*
763 	 * Calculate the size of the return buffer.
764 	 * The base size is the number of elements * the sizes of the
765 	 * structures. Additional space for the strings is added below.
766 	 * The minus one is to subtract the size of the u8 Source[1]
767 	 * member because it is added below.
768 	 *
769 	 * But each PRT_ENTRY structure has a pointer to a string and
770 	 * the size of that string must be found.
771 	 */
772 	top_object_list = package_object->package.elements;
773 
774 	for (index = 0; index < number_of_elements; index++) {
775 
776 		/* Dereference the subpackage */
777 
778 		package_element = *top_object_list;
779 
780 		/* We must have a valid Package object */
781 
782 		if (!package_element ||
783 		    (package_element->common.type != ACPI_TYPE_PACKAGE)) {
784 			return_ACPI_STATUS(AE_AML_OPERAND_TYPE);
785 		}
786 
787 		/*
788 		 * The sub_object_list will now point to an array of the
789 		 * four IRQ elements: Address, Pin, Source and source_index
790 		 */
791 		sub_object_list = package_element->package.elements;
792 
793 		/* Scan the irq_table_elements for the Source Name String */
794 
795 		name_found = FALSE;
796 
797 		for (table_index = 0;
798 		     table_index < package_element->package.count
799 		     && !name_found; table_index++) {
800 			if (*sub_object_list &&	/* Null object allowed */
801 			    ((ACPI_TYPE_STRING ==
802 			      (*sub_object_list)->common.type) ||
803 			     ((ACPI_TYPE_LOCAL_REFERENCE ==
804 			       (*sub_object_list)->common.type) &&
805 			      ((*sub_object_list)->reference.class ==
806 			       ACPI_REFCLASS_NAME)))) {
807 				name_found = TRUE;
808 			} else {
809 				/* Look at the next element */
810 
811 				sub_object_list++;
812 			}
813 		}
814 
815 		temp_size_needed += (sizeof(struct acpi_pci_routing_table) - 4);
816 
817 		/* Was a String type found? */
818 
819 		if (name_found) {
820 			if ((*sub_object_list)->common.type == ACPI_TYPE_STRING) {
821 				/*
822 				 * The length String.Length field does not include the
823 				 * terminating NULL, add 1
824 				 */
825 				temp_size_needed += ((acpi_size)
826 						     (*sub_object_list)->string.
827 						     length + 1);
828 			} else {
829 				temp_size_needed += acpi_ns_get_pathname_length((*sub_object_list)->reference.node);
830 			}
831 		} else {
832 			/*
833 			 * If no name was found, then this is a NULL, which is
834 			 * translated as a u32 zero.
835 			 */
836 			temp_size_needed += sizeof(u32);
837 		}
838 
839 		/* Round up the size since each element must be aligned */
840 
841 		temp_size_needed = ACPI_ROUND_UP_TO_64BIT(temp_size_needed);
842 
843 		/* Point to the next union acpi_operand_object */
844 
845 		top_object_list++;
846 	}
847 
848 	/*
849 	 * Add an extra element to the end of the list, essentially a
850 	 * NULL terminator
851 	 */
852 	*buffer_size_needed =
853 	    temp_size_needed + sizeof(struct acpi_pci_routing_table);
854 	return_ACPI_STATUS(AE_OK);
855 }
856