summaryrefslogtreecommitdiffstats
path: root/drivers/acpi/pptt.c
blob: 1e7ac0bd0d3a090c42136e2b4fc213a31924516c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
// SPDX-License-Identifier: GPL-2.0
/*
 * pptt.c - parsing of Processor Properties Topology Table (PPTT)
 *
 * Copyright (C) 2018, ARM
 *
 * This file implements parsing of the Processor Properties Topology Table
 * which is optionally used to describe the processor and cache topology.
 * Due to the relative pointers used throughout the table, this doesn't
 * leverage the existing subtable parsing in the kernel.
 *
 * The PPTT structure is an inverted tree, with each node potentially
 * holding one or two inverted tree data structures describing
 * the caches available at that level. Each cache structure optionally
 * contains properties describing the cache at a given level which can be
 * used to override hardware probed values.
 */
#define pr_fmt(fmt) "ACPI PPTT: " fmt

#include <linux/acpi.h>
#include <linux/cacheinfo.h>
#include <acpi/processor.h>

static struct acpi_subtable_header *fetch_pptt_subtable(struct acpi_table_header *table_hdr,
							u32 pptt_ref)
{
	struct acpi_subtable_header *entry;

	/* there isn't a subtable at reference 0 */
	if (pptt_ref < sizeof(struct acpi_subtable_header))
		return NULL;

	if (pptt_ref + sizeof(struct acpi_subtable_header) > table_hdr->length)
		return NULL;

	entry = ACPI_ADD_PTR(struct acpi_subtable_header, table_hdr, pptt_ref);

	if (entry->length == 0)
		return NULL;

	if (pptt_ref + entry->length > table_hdr->length)
		return NULL;

	return entry;
}

static struct acpi_pptt_processor *fetch_pptt_node(struct acpi_table_header *table_hdr,
						   u32 pptt_ref)
{
	return (struct acpi_pptt_processor *)fetch_pptt_subtable(table_hdr, pptt_ref);
}

static struct acpi_pptt_cache *fetch_pptt_cache(struct acpi_table_header *table_hdr,
						u32 pptt_ref)
{
	return (struct acpi_pptt_cache *)fetch_pptt_subtable(table_hdr, pptt_ref);
}

static struct acpi_subtable_header *acpi_get_pptt_resource(struct acpi_table_header *table_hdr,
							   struct acpi_pptt_processor *node,
							   int resource)
{
	u32 *ref;

	if (resource >= node->number_of_priv_resources)
		return NULL;

	ref = ACPI_ADD_PTR(u32, node, sizeof(struct acpi_pptt_processor));
	ref += resource;

	return fetch_pptt_subtable(table_hdr, *ref);
}

static inline bool acpi_pptt_match_type(int table_type, int type)
{
	return ((table_type & ACPI_PPTT_MASK_CACHE_TYPE) == type ||
		table_type & ACPI_PPTT_CACHE_TYPE_UNIFIED & type);
}

/**
 * acpi_pptt_walk_cache() - Attempt to find the requested acpi_pptt_cache
 * @table_hdr: Pointer to the head of the PPTT table
 * @local_level: passed res reflects this cache level
 * @res: cache resource in the PPTT we want to walk
 * @found: returns a pointer to the requested level if found
 * @level: the requested cache level
 * @type: the requested cache type
 *
 * Attempt to find a given cache level, while counting the max number
 * of cache levels for the cache node.
 *
 * Given a pptt resource, verify that it is a cache node, then walk
 * down each level of caches, counting how many levels are found
 * as well as checking the cache type (icache, dcache, unified). If a
 * level & type match, then we set found, and continue the search.
 * Once the entire cache branch has been walked return its max
 * depth.
 *
 * Return: The cache structure and the level we terminated with.
 */
static int acpi_pptt_walk_cache(struct acpi_table_header *table_hdr,
				int local_level,
				struct acpi_subtable_header *res,
				struct acpi_pptt_cache **found,
				int level, int type)
{
	struct acpi_pptt_cache *cache;

	if (res->type != ACPI_PPTT_TYPE_CACHE)
		return 0;

	cache = (struct acpi_pptt_cache *) res;
	while (cache) {
		local_level++;

		if (local_level == level &&
		    cache->flags & ACPI_PPTT_CACHE_TYPE_VALID &&
		    acpi_pptt_match_type(cache->attributes, type)) {
			if (*found != NULL && cache != *found)
				pr_warn("Found duplicate cache level/type unable to determine uniqueness\n");

			pr_debug("Found cache @ level %d\n", level);
			*found = cache;
			/*
			 * continue looking at this node's resource list
			 * to verify that we don't find a duplicate
			 * cache node.
			 */
		}
		cache = fetch_pptt_cache(table_hdr, cache->next_level_of_cache);
	}
	return local_level;
}

static struct acpi_pptt_cache *acpi_find_cache_level(struct acpi_table_header *table_hdr,
						     struct acpi_pptt_processor *cpu_node,
						     int *starting_level, int level,
						     int type)
{
	struct acpi_subtable_header *res;
	int number_of_levels = *starting_level;
	int resource = 0;
	struct acpi_pptt_cache *ret = NULL;
	int local_level;

	/* walk down from processor node */
	while ((res = acpi_get_pptt_resource(table_hdr, cpu_node, resource))) {
		resource++;

		local_level = acpi_pptt_walk_cache(table_hdr, *starting_level,
						   res, &ret, level, type);
		/*
		 * we are looking for the max depth. Since its potentially
		 * possible for a given node to have resources with differing
		 * depths verify that the depth we have found is the largest.
		 */
		if (number_of_levels < local_level)
			number_of_levels = local_level;
	}
	if (number_of_levels > *starting_level)
		*starting_level = number_of_levels;

	return ret;
}

/**
 * acpi_count_levels() - Given a PPTT table, and a CPU node, count the caches
 * @table_hdr: Pointer to the head of the PPTT table
 * @cpu_node: processor node we wish to count caches for
 *
 * Given a processor node containing a processing unit, walk into it and count
 * how many levels exist solely for it, and then walk up each level until we hit
 * the root node (ignore the package level because it may be possible to have
 * caches that exist across packages). Count the number of cache levels that
 * exist at each level on the way up.
 *
 * Return: Total number of levels found.
 */
static int acpi_count_levels(struct acpi_table_header *table_hdr,
			     struct acpi_pptt_processor *cpu_node)
{
	int total_levels = 0;

	do {
		acpi_find_cache_level(table_hdr, cpu_node, &total_levels, 0, 0);
		cpu_node = fetch_pptt_node(table_hdr, cpu_node->parent);
	} while (cpu_node);

	return total_levels;
}

/**
 * acpi_pptt_leaf_node() - Given a processor node, determine if its a leaf
 * @table_hdr: Pointer to the head of the PPTT table
 * @node: passed node is checked to see if its a leaf
 *
 * Determine if the *node parameter is a leaf node by iterating the
 * PPTT table, looking for nodes which reference it.
 *
 * Return: 0 if we find a node referencing the passed node (or table error),
 * or 1 if we don't.
 */
static int acpi_pptt_leaf_node(struct acpi_table_header *table_hdr,
			       struct acpi_pptt_processor *node)
{
	struct acpi_subtable_header *entry;
	unsigned long table_end;
	u32 node_entry;
	struct acpi_pptt_processor *cpu_node;
	u32 proc_sz;

	if (table_hdr->revision > 1)
		return (node->flags & ACPI_PPTT_ACPI_LEAF_NODE);

	table_end = (unsigned long)table_hdr + table_hdr->length;
	node_entry = ACPI_PTR_DIFF(node, table_hdr);
	entry = ACPI_ADD_PTR(struct acpi_subtable_header, table_hdr,
			     sizeof(struct acpi_table_pptt));
	proc_sz = sizeof(struct acpi_pptt_processor *);

	while ((unsigned long)entry + proc_sz < table_end) {
		cpu_node = (struct acpi_pptt_processor *)entry;
		if (entry->type == ACPI_PPTT_TYPE_PROCESSOR &&
		    cpu_node->parent == node_entry)
			return 0;
		if (entry->length == 0)
			return 0;
		entry = ACPI_ADD_PTR(struct acpi_subtable_header, entry,
				     entry->length);

	}
	return 1;
}

/**
 * acpi_find_processor_node() - Given a PPTT table find the requested processor
 * @table_hdr:  Pointer to the head of the PPTT table
 * @acpi_cpu_id: CPU we are searching for
 *
 * Find the subtable entry describing the provided processor.
 * This is done by iterating the PPTT table looking for processor nodes
 * which have an acpi_processor_id that matches the acpi_cpu_id parameter
 * passed into the function. If we find a node that matches this criteria
 * we verify that its a leaf node in the topology rather than depending
 * on the valid flag, which doesn't need to be set for leaf nodes.
 *
 * Return: NULL, or the processors acpi_pptt_processor*
 */
static struct acpi_pptt_processor *acpi_find_processor_node(struct acpi_table_header *table_hdr,
							    u32 acpi_cpu_id)
{
	struct acpi_subtable_header *entry;
	unsigned long table_end;
	struct acpi_pptt_processor *cpu_node;
	u32 proc_sz;

	table_end = (unsigned long)table_hdr + table_hdr->length;
	entry = ACPI_ADD_PTR(struct acpi_subtable_header, table_hdr,
			     sizeof(struct acpi_table_pptt));
	proc_sz = sizeof(struct acpi_pptt_processor *);

	/* find the processor structure associated with this cpuid */
	while ((unsigned long)entry + proc_sz < table_end) {
		cpu_node = (struct acpi_pptt_processor *)entry;

		if (entry->length == 0) {
			pr_warn("Invalid zero length subtable\n");
			break;
		}
		if (entry->type == ACPI_PPTT_TYPE_PROCESSOR &&
		    acpi_cpu_id == cpu_node->acpi_processor_id &&
		     acpi_pptt_leaf_node(table_hdr, cpu_node)) {
			return (struct acpi_pptt_processor *)entry;
		}

		entry = ACPI_ADD_PTR(struct acpi_subtable_header, entry,
				     entry->length);
	}

	return NULL;
}

static int acpi_find_cache_levels(struct acpi_table_header *table_hdr,
				  u32 acpi_cpu_id)
{
	int number_of_levels = 0;
	struct acpi_pptt_processor *cpu;

	cpu = acpi_find_processor_node(table_hdr, acpi_cpu_id);
	if (cpu)
		number_of_levels = acpi_count_levels(table_hdr, cpu);

	return number_of_levels;
}

static u8 acpi_cache_type(enum cache_type type)
{
	switch (type) {
	case CACHE_TYPE_DATA:
		pr_debug("Looking for data cache\n");
		return ACPI_PPTT_CACHE_TYPE_DATA;
	case CACHE_TYPE_INST:
		pr_debug("Looking for instruction cache\n");
		return ACPI_PPTT_CACHE_TYPE_INSTR;
	default:
	case CACHE_TYPE_UNIFIED:
		pr_debug("Looking for unified cache\n");
		/*
		 * It is important that ACPI_PPTT_CACHE_TYPE_UNIFIED
		 * contains the bit pattern that will match both
		 * ACPI unified bit patterns because we use it later
		 * to match both cases.
		 */
		return ACPI_PPTT_CACHE_TYPE_UNIFIED;
	}
}

static struct acpi_pptt_cache *acpi_find_cache_node(struct acpi_table_header *table_hdr,
						    u32 acpi_cpu_id,
						    enum cache_type type,
						    unsigned int level,
						    struct acpi_pptt_processor **node)
{
	int total_levels = 0;
	struct acpi_pptt_cache *found = NULL;
	struct acpi_pptt_processor *cpu_node;
	u8 acpi_type = acpi_cache_type(type);

	pr_debug("Looking for CPU %d's level %d cache type %d\n",
		 acpi_cpu_id, level, acpi_type);

	cpu_node = acpi_find_processor_node(table_hdr, acpi_cpu_id);

	while (cpu_node && !found) {
		found = acpi_find_cache_level(table_hdr, cpu_node,
					      &total_levels, level, acpi_type);
		*node = cpu_node;
		cpu_node = fetch_pptt_node(table_hdr, cpu_node->parent);
	}

	return found;
}

/**
 * update_cache_properties() - Update cacheinfo for the given processor
 * @this_leaf: Kernel cache info structure being updated
 * @found_cache: The PPTT node describing this cache instance
 * @cpu_node: A unique reference to describe this cache instance
 *
 * The ACPI spec implies that the fields in the cache structures are used to
 * extend and correct the information probed from the hardware. Lets only
 * set fields that we determine are VALID.
 *
 * Return: nothing. Side effect of updating the global cacheinfo
 */
static void update_cache_properties(struct cacheinfo *this_leaf,
				    struct acpi_pptt_cache *found_cache,
				    struct acpi_pptt_processor *cpu_node)
{
	this_leaf->fw_token = cpu_node;
	if (found_cache->flags & ACPI_PPTT_SIZE_PROPERTY_VALID)
		this_leaf->size = found_cache->size;
	if (found_cache->flags & ACPI_PPTT_LINE_SIZE_VALID)
		this_leaf->coherency_line_size = found_cache->line_size;
	if (found_cache->flags & ACPI_PPTT_NUMBER_OF_SETS_VALID)
		this_leaf->number_of_sets = found_cache->number_of_sets;
	if (found_cache->flags & ACPI_PPTT_ASSOCIATIVITY_VALID)
		this_leaf->ways_of_associativity = found_cache->associativity;
	if (found_cache->flags & ACPI_PPTT_WRITE_POLICY_VALID) {
		switch (found_cache->attributes & ACPI_PPTT_MASK_WRITE_POLICY) {
		case ACPI_PPTT_CACHE_POLICY_WT:
			this_leaf->attributes = CACHE_WRITE_THROUGH;
			break;
		case ACPI_PPTT_CACHE_POLICY_WB:
			this_leaf->attributes = CACHE_WRITE_BACK;
			break;
		}
	}
	if (found_cache->flags & ACPI_PPTT_ALLOCATION_TYPE_VALID) {
		switch (found_cache->attributes & ACPI_PPTT_MASK_ALLOCATION_TYPE) {
		case ACPI_PPTT_CACHE_READ_ALLOCATE:
			this_leaf->attributes |= CACHE_READ_ALLOCATE;
			break;
		case ACPI_PPTT_CACHE_WRITE_ALLOCATE:
			this_leaf->attributes |= CACHE_WRITE_ALLOCATE;
			break;
		case ACPI_PPTT_CACHE_RW_ALLOCATE:
		case ACPI_PPTT_CACHE_RW_ALLOCATE_ALT:
			this_leaf->attributes |=
				CACHE_READ_ALLOCATE | CACHE_WRITE_ALLOCATE;
			break;
		}
	}
	/*
	 * If cache type is NOCACHE, then the cache hasn't been specified
	 * via other mechanisms.  Update the type if a cache type has been
	 * provided.
	 *
	 * Note, we assume such caches are unified based on conventional system
	 * design and known examples.  Significant work is required elsewhere to
	 * fully support data/instruction only type caches which are only
	 * specified in PPTT.
	 */
	if (this_leaf->type == CACHE_TYPE_NOCACHE &&
	    found_cache->flags & ACPI_PPTT_CACHE_TYPE_VALID)
		this_leaf->type = CACHE_TYPE_UNIFIED;
}

static void cache_setup_acpi_cpu(struct acpi_table_header *table,
				 unsigned int cpu)
{
	struct acpi_pptt_cache *found_cache;
	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
	u32 acpi_cpu_id = get_acpi_id_for_cpu(cpu);
	struct cacheinfo *this_leaf;
	unsigned int index = 0;
	struct acpi_pptt_processor *cpu_node = NULL;

	while (index < get_cpu_cacheinfo(cpu)->num_leaves) {
		this_leaf = this_cpu_ci->info_list + index;
		found_cache = acpi_find_cache_node(table, acpi_cpu_id,
						   this_leaf->type,
						   this_leaf->level,
						   &cpu_node);
		pr_debug("found = %p %p\n", found_cache, cpu_node);
		if (found_cache)
			update_cache_properties(this_leaf,
						found_cache,
						cpu_node);

		index++;
	}
}

static bool flag_identical(struct acpi_table_header *table_hdr,
			   struct acpi_pptt_processor *cpu)
{
	struct acpi_pptt_processor *next;

	/* heterogeneous machines must use PPTT revision > 1 */
	if (table_hdr->revision < 2)
		return false;

	/* Locate the last node in the tree with IDENTICAL set */
	if (cpu->flags & ACPI_PPTT_ACPI_IDENTICAL) {
		next = fetch_pptt_node(table_hdr, cpu->parent);
		if (!(next && next->flags & ACPI_PPTT_ACPI_IDENTICAL))
			return true;
	}

	return false;
}

/* Passing level values greater than this will result in search termination */
#define PPTT_ABORT_PACKAGE 0xFF

static struct acpi_pptt_processor *acpi_find_processor_tag(struct acpi_table_header *table_hdr,
							   struct acpi_pptt_processor *cpu,
							   int level, int flag)
{
	struct acpi_pptt_processor *prev_node;

	while (cpu && level) {
		/* special case the identical flag to find last identical */
		if (flag == ACPI_PPTT_ACPI_IDENTICAL) {
			if (flag_identical(table_hdr, cpu))
				break;
		} else if (cpu->flags & flag)
			break;
		pr_debug("level %d\n", level);
		prev_node = fetch_pptt_node(table_hdr, cpu->parent);
		if (prev_node == NULL)
			break;
		cpu = prev_node;
		level--;
	}
	return cpu;
}

static void acpi_pptt_warn_missing(void)
{
	pr_warn_once("No PPTT table found, CPU and cache topology may be inaccurate\n");
}

/**
 * topology_get_acpi_cpu_tag() - Find a unique topology value for a feature
 * @table: Pointer to the head of the PPTT table
 * @cpu: Kernel logical CPU number
 * @level: A level that terminates the search
 * @flag: A flag which terminates the search
 *
 * Get a unique value given a CPU, and a topology level, that can be
 * matched to determine which cpus share common topological features
 * at that level.
 *
 * Return: Unique value, or -ENOENT if unable to locate CPU
 */
static int topology_get_acpi_cpu_tag(struct acpi_table_header *table,
				     unsigned int cpu, int level, int flag)
{
	struct acpi_pptt_processor *cpu_node;
	u32 acpi_cpu_id = get_acpi_id_for_cpu(cpu);

	cpu_node = acpi_find_processor_node(table, acpi_cpu_id);
	if (cpu_node) {
		cpu_node = acpi_find_processor_tag(table, cpu_node,
						   level, flag);
		/*
		 * As per specification if the processor structure represents
		 * an actual processor, then ACPI processor ID must be valid.
		 * For processor containers ACPI_PPTT_ACPI_PROCESSOR_ID_VALID
		 * should be set if the UID is valid
		 */
		if (level == 0 ||
		    cpu_node->flags & ACPI_PPTT_ACPI_PROCESSOR_ID_VALID)
			return cpu_node->acpi_processor_id;
		return ACPI_PTR_DIFF(cpu_node, table);
	}
	pr_warn_once("PPTT table found, but unable to locate core %d (%d)\n",
		    cpu, acpi_cpu_id);
	return -ENOENT;
}

static int find_acpi_cpu_topology_tag(unsigned int cpu, int level, int flag)
{
	struct acpi_table_header *table;
	acpi_status status;
	int retval;

	status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);
	if (ACPI_FAILURE(status)) {
		acpi_pptt_warn_missing();
		return -ENOENT;
	}
	retval = topology_get_acpi_cpu_tag(table, cpu, level, flag);
	pr_debug("Topology Setup ACPI CPU %d, level %d ret = %d\n",
		 cpu, level, retval);
	acpi_put_table(table);

	return retval;
}

/**
 * acpi_find_last_cache_level() - Determines the number of cache levels for a PE
 * @cpu: Kernel logical CPU number
 *
 * Given a logical CPU number, returns the number of levels of cache represented
 * in the PPTT. Errors caused by lack of a PPTT table, or otherwise, return 0
 * indicating we didn't find any cache levels.
 *
 * Return: Cache levels visible to this core.
 */
int acpi_find_last_cache_level(unsigned int cpu)
{
	u32 acpi_cpu_id;
	struct acpi_table_header *table;
	int number_of_levels = 0;
	acpi_status status;

	pr_debug("Cache Setup find last level CPU=%d\n", cpu);

	acpi_cpu_id = get_acpi_id_for_cpu(cpu);
	status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);
	if (ACPI_FAILURE(status)) {
		acpi_pptt_warn_missing();
	} else {
		number_of_levels = acpi_find_cache_levels(table, acpi_cpu_id);
		acpi_put_table(table);
	}
	pr_debug("Cache Setup find last level level=%d\n", number_of_levels);

	return number_of_levels;
}

/**
 * cache_setup_acpi() - Override CPU cache topology with data from the PPTT
 * @cpu: Kernel logical CPU number
 *
 * Updates the global cache info provided by cpu_get_cacheinfo()
 * when there are valid properties in the acpi_pptt_cache nodes. A
 * successful parse may not result in any updates if none of the
 * cache levels have any valid flags set.  Further, a unique value is
 * associated with each known CPU cache entry. This unique value
 * can be used to determine whether caches are shared between CPUs.
 *
 * Return: -ENOENT on failure to find table, or 0 on success
 */
int cache_setup_acpi(unsigned int cpu)
{
	struct acpi_table_header *table;
	acpi_status status;

	pr_debug("Cache Setup ACPI CPU %d\n", cpu);

	status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);
	if (ACPI_FAILURE(status)) {
		acpi_pptt_warn_missing();
		return -ENOENT;
	}

	cache_setup_acpi_cpu(table, cpu);
	acpi_put_table(table);

	return status;
}

/**
 * find_acpi_cpu_topology() - Determine a unique topology value for a given CPU
 * @cpu: Kernel logical CPU number
 * @level: The topological level for which we would like a unique ID
 *
 * Determine a topology unique ID for each thread/core/cluster/mc_grouping
 * /socket/etc. This ID can then be used to group peers, which will have
 * matching ids.
 *
 * The search terminates when either the requested level is found or
 * we reach a root node. Levels beyond the termination point will return the
 * same unique ID. The unique id for level 0 is the acpi processor id. All
 * other levels beyond this use a generated value to uniquely identify
 * a topological feature.
 *
 * Return: -ENOENT if the PPTT doesn't exist, or the CPU cannot be found.
 * Otherwise returns a value which represents a unique topological feature.
 */
int find_acpi_cpu_topology(unsigned int cpu, int level)
{
	return find_acpi_cpu_topology_tag(cpu, level, 0);
}

/**
 * find_acpi_cpu_cache_topology() - Determine a unique cache topology value
 * @cpu: Kernel logical CPU number
 * @level: The cache level for which we would like a unique ID
 *
 * Determine a unique ID for each unified cache in the system
 *
 * Return: -ENOENT if the PPTT doesn't exist, or the CPU cannot be found.
 * Otherwise returns a value which represents a unique topological feature.
 */
int find_acpi_cpu_cache_topology(unsigned int cpu, int level)
{
	struct acpi_table_header *table;
	struct acpi_pptt_cache *found_cache;
	acpi_status status;
	u32 acpi_cpu_id = get_acpi_id_for_cpu(cpu);
	struct acpi_pptt_processor *cpu_node = NULL;
	int ret = -1;

	status = acpi_get_table(ACPI_SIG_PPTT, 0, &table);
	if (ACPI_FAILURE(status)) {
		acpi_pptt_warn_missing();
		return -ENOENT;
	}

	found_cache = acpi_find_cache_node(table, acpi_cpu_id,
					   CACHE_TYPE_UNIFIED,
					   level,
					   &cpu_node);
	if (found_cache)
		ret = ACPI_PTR_DIFF(cpu_node, table);

	acpi_put_table(table);

	return ret;
}


/**
 * find_acpi_cpu_topology_package() - Determine a unique CPU package value
 * @cpu: Kernel logical CPU number
 *
 * Determine a topology unique package ID for the given CPU.
 * This ID can then be used to group peers, which will have matching ids.
 *
 * The search terminates when either a level is found with the PHYSICAL_PACKAGE
 * flag set or we reach a root node.
 *
 * Return: -ENOENT if the PPTT doesn't exist, or the CPU cannot be found.
 * Otherwise returns a value which represents the package for this CPU.
 */
int find_acpi_cpu_topology_package(unsigned int cpu)
{
	return find_acpi_cpu_topology_tag(cpu, PPTT_ABORT_PACKAGE,
					  ACPI_PPTT_PHYSICAL_PACKAGE);
}

/**
 * find_acpi_cpu_topology_hetero_id() - Get a core architecture tag
 * @cpu: Kernel logical CPU number
 *
 * Determine a unique heterogeneous tag for the given CPU. CPUs with the same
 * implementation should have matching tags.
 *
 * The returned tag can be used to group peers with identical implementation.
 *
 * The search terminates when a level is found with the identical implementation
 * flag set or we reach a root node.
 *
 * Due to limitations in the PPTT data structure, there may be rare situations
 * where two cores in a heterogeneous machine may be identical, but won't have
 * the same tag.
 *
 * Return: -ENOENT if the PPTT doesn't exist, or the CPU cannot be found.
 * Otherwise returns a value which represents a group of identical cores
 * similar to this CPU.
 */
int find_acpi_cpu_topology_hetero_id(unsigned int cpu)
{
	return find_acpi_cpu_topology_tag(cpu, PPTT_ABORT_PACKAGE,
					  ACPI_PPTT_ACPI_IDENTICAL);
}