summaryrefslogtreecommitdiffstats
path: root/drivers/interconnect/core.c
blob: 4f9bdb7f9165e334b489d811fd6e155bffd7a771 (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
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
// SPDX-License-Identifier: GPL-2.0
/*
 * Interconnect framework core driver
 *
 * Copyright (c) 2017-2019, Linaro Ltd.
 * Author: Georgi Djakov <georgi.djakov@linaro.org>
 */

#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/idr.h>
#include <linux/init.h>
#include <linux/interconnect.h>
#include <linux/interconnect-provider.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/overflow.h>

#include "internal.h"

static DEFINE_IDR(icc_idr);
static LIST_HEAD(icc_providers);
static DEFINE_MUTEX(icc_lock);
static struct dentry *icc_debugfs_dir;

static void icc_summary_show_one(struct seq_file *s, struct icc_node *n)
{
	if (!n)
		return;

	seq_printf(s, "%-30s %12u %12u\n",
		   n->name, n->avg_bw, n->peak_bw);
}

static int icc_summary_show(struct seq_file *s, void *data)
{
	struct icc_provider *provider;

	seq_puts(s, " node                                   avg         peak\n");
	seq_puts(s, "--------------------------------------------------------\n");

	mutex_lock(&icc_lock);

	list_for_each_entry(provider, &icc_providers, provider_list) {
		struct icc_node *n;

		list_for_each_entry(n, &provider->nodes, node_list) {
			struct icc_req *r;

			icc_summary_show_one(s, n);
			hlist_for_each_entry(r, &n->req_list, req_node) {
				if (!r->dev)
					continue;

				seq_printf(s, "    %-26s %12u %12u\n",
					   dev_name(r->dev), r->avg_bw,
					   r->peak_bw);
			}
		}
	}

	mutex_unlock(&icc_lock);

	return 0;
}
DEFINE_SHOW_ATTRIBUTE(icc_summary);

static struct icc_node *node_find(const int id)
{
	return idr_find(&icc_idr, id);
}

static struct icc_path *path_init(struct device *dev, struct icc_node *dst,
				  ssize_t num_nodes)
{
	struct icc_node *node = dst;
	struct icc_path *path;
	int i;

	path = kzalloc(struct_size(path, reqs, num_nodes), GFP_KERNEL);
	if (!path)
		return ERR_PTR(-ENOMEM);

	path->num_nodes = num_nodes;

	for (i = num_nodes - 1; i >= 0; i--) {
		node->provider->users++;
		hlist_add_head(&path->reqs[i].req_node, &node->req_list);
		path->reqs[i].node = node;
		path->reqs[i].dev = dev;
		/* reference to previous node was saved during path traversal */
		node = node->reverse;
	}

	return path;
}

static struct icc_path *path_find(struct device *dev, struct icc_node *src,
				  struct icc_node *dst)
{
	struct icc_path *path = ERR_PTR(-EPROBE_DEFER);
	struct icc_node *n, *node = NULL;
	struct list_head traverse_list;
	struct list_head edge_list;
	struct list_head visited_list;
	size_t i, depth = 1;
	bool found = false;

	INIT_LIST_HEAD(&traverse_list);
	INIT_LIST_HEAD(&edge_list);
	INIT_LIST_HEAD(&visited_list);

	list_add(&src->search_list, &traverse_list);
	src->reverse = NULL;

	do {
		list_for_each_entry_safe(node, n, &traverse_list, search_list) {
			if (node == dst) {
				found = true;
				list_splice_init(&edge_list, &visited_list);
				list_splice_init(&traverse_list, &visited_list);
				break;
			}
			for (i = 0; i < node->num_links; i++) {
				struct icc_node *tmp = node->links[i];

				if (!tmp) {
					path = ERR_PTR(-ENOENT);
					goto out;
				}

				if (tmp->is_traversed)
					continue;

				tmp->is_traversed = true;
				tmp->reverse = node;
				list_add_tail(&tmp->search_list, &edge_list);
			}
		}

		if (found)
			break;

		list_splice_init(&traverse_list, &visited_list);
		list_splice_init(&edge_list, &traverse_list);

		/* count the hops including the source */
		depth++;

	} while (!list_empty(&traverse_list));

out:

	/* reset the traversed state */
	list_for_each_entry_reverse(n, &visited_list, search_list)
		n->is_traversed = false;

	if (found)
		path = path_init(dev, dst, depth);

	return path;
}

/*
 * We want the path to honor all bandwidth requests, so the average and peak
 * bandwidth requirements from each consumer are aggregated at each node.
 * The aggregation is platform specific, so each platform can customize it by
 * implementing its own aggregate() function.
 */

static int aggregate_requests(struct icc_node *node)
{
	struct icc_provider *p = node->provider;
	struct icc_req *r;

	node->avg_bw = 0;
	node->peak_bw = 0;

	if (p->pre_aggregate)
		p->pre_aggregate(node);

	hlist_for_each_entry(r, &node->req_list, req_node)
		p->aggregate(node, r->tag, r->avg_bw, r->peak_bw,
			     &node->avg_bw, &node->peak_bw);

	return 0;
}

static int apply_constraints(struct icc_path *path)
{
	struct icc_node *next, *prev = NULL;
	int ret = -EINVAL;
	int i;

	for (i = 0; i < path->num_nodes; i++) {
		next = path->reqs[i].node;

		/*
		 * Both endpoints should be valid master-slave pairs of the
		 * same interconnect provider that will be configured.
		 */
		if (!prev || next->provider != prev->provider) {
			prev = next;
			continue;
		}

		/* set the constraints */
		ret = next->provider->set(prev, next);
		if (ret)
			goto out;

		prev = next;
	}
out:
	return ret;
}

/* of_icc_xlate_onecell() - Translate function using a single index.
 * @spec: OF phandle args to map into an interconnect node.
 * @data: private data (pointer to struct icc_onecell_data)
 *
 * This is a generic translate function that can be used to model simple
 * interconnect providers that have one device tree node and provide
 * multiple interconnect nodes. A single cell is used as an index into
 * an array of icc nodes specified in the icc_onecell_data struct when
 * registering the provider.
 */
struct icc_node *of_icc_xlate_onecell(struct of_phandle_args *spec,
				      void *data)
{
	struct icc_onecell_data *icc_data = data;
	unsigned int idx = spec->args[0];

	if (idx >= icc_data->num_nodes) {
		pr_err("%s: invalid index %u\n", __func__, idx);
		return ERR_PTR(-EINVAL);
	}

	return icc_data->nodes[idx];
}
EXPORT_SYMBOL_GPL(of_icc_xlate_onecell);

/**
 * of_icc_get_from_provider() - Look-up interconnect node
 * @spec: OF phandle args to use for look-up
 *
 * Looks for interconnect provider under the node specified by @spec and if
 * found, uses xlate function of the provider to map phandle args to node.
 *
 * Returns a valid pointer to struct icc_node on success or ERR_PTR()
 * on failure.
 */
static struct icc_node *of_icc_get_from_provider(struct of_phandle_args *spec)
{
	struct icc_node *node = ERR_PTR(-EPROBE_DEFER);
	struct icc_provider *provider;

	if (!spec || spec->args_count != 1)
		return ERR_PTR(-EINVAL);

	mutex_lock(&icc_lock);
	list_for_each_entry(provider, &icc_providers, provider_list) {
		if (provider->dev->of_node == spec->np)
			node = provider->xlate(spec, provider->data);
		if (!IS_ERR(node))
			break;
	}
	mutex_unlock(&icc_lock);

	return node;
}

/**
 * of_icc_get() - get a path handle from a DT node based on name
 * @dev: device pointer for the consumer device
 * @name: interconnect path name
 *
 * This function will search for a path between two endpoints and return an
 * icc_path handle on success. Use icc_put() to release constraints when they
 * are not needed anymore.
 * If the interconnect API is disabled, NULL is returned and the consumer
 * drivers will still build. Drivers are free to handle this specifically,
 * but they don't have to.
 *
 * Return: icc_path pointer on success or ERR_PTR() on error. NULL is returned
 * when the API is disabled or the "interconnects" DT property is missing.
 */
struct icc_path *of_icc_get(struct device *dev, const char *name)
{
	struct icc_path *path = ERR_PTR(-EPROBE_DEFER);
	struct icc_node *src_node, *dst_node;
	struct device_node *np = NULL;
	struct of_phandle_args src_args, dst_args;
	int idx = 0;
	int ret;

	if (!dev || !dev->of_node)
		return ERR_PTR(-ENODEV);

	np = dev->of_node;

	/*
	 * When the consumer DT node do not have "interconnects" property
	 * return a NULL path to skip setting constraints.
	 */
	if (!of_find_property(np, "interconnects", NULL))
		return NULL;

	/*
	 * We use a combination of phandle and specifier for endpoint. For now
	 * lets support only global ids and extend this in the future if needed
	 * without breaking DT compatibility.
	 */
	if (name) {
		idx = of_property_match_string(np, "interconnect-names", name);
		if (idx < 0)
			return ERR_PTR(idx);
	}

	ret = of_parse_phandle_with_args(np, "interconnects",
					 "#interconnect-cells", idx * 2,
					 &src_args);
	if (ret)
		return ERR_PTR(ret);

	of_node_put(src_args.np);

	ret = of_parse_phandle_with_args(np, "interconnects",
					 "#interconnect-cells", idx * 2 + 1,
					 &dst_args);
	if (ret)
		return ERR_PTR(ret);

	of_node_put(dst_args.np);

	src_node = of_icc_get_from_provider(&src_args);

	if (IS_ERR(src_node)) {
		if (PTR_ERR(src_node) != -EPROBE_DEFER)
			dev_err(dev, "error finding src node: %ld\n",
				PTR_ERR(src_node));
		return ERR_CAST(src_node);
	}

	dst_node = of_icc_get_from_provider(&dst_args);

	if (IS_ERR(dst_node)) {
		if (PTR_ERR(dst_node) != -EPROBE_DEFER)
			dev_err(dev, "error finding dst node: %ld\n",
				PTR_ERR(dst_node));
		return ERR_CAST(dst_node);
	}

	mutex_lock(&icc_lock);
	path = path_find(dev, src_node, dst_node);
	mutex_unlock(&icc_lock);
	if (IS_ERR(path)) {
		dev_err(dev, "%s: invalid path=%ld\n", __func__, PTR_ERR(path));
		return path;
	}

	if (name)
		path->name = kstrdup_const(name, GFP_KERNEL);
	else
		path->name = kasprintf(GFP_KERNEL, "%s-%s",
				       src_node->name, dst_node->name);

	return path;
}
EXPORT_SYMBOL_GPL(of_icc_get);

/**
 * icc_set_tag() - set an optional tag on a path
 * @path: the path we want to tag
 * @tag: the tag value
 *
 * This function allows consumers to append a tag to the requests associated
 * with a path, so that a different aggregation could be done based on this tag.
 */
void icc_set_tag(struct icc_path *path, u32 tag)
{
	int i;

	if (!path)
		return;

	mutex_lock(&icc_lock);

	for (i = 0; i < path->num_nodes; i++)
		path->reqs[i].tag = tag;

	mutex_unlock(&icc_lock);
}
EXPORT_SYMBOL_GPL(icc_set_tag);

/**
 * icc_set_bw() - set bandwidth constraints on an interconnect path
 * @path: reference to the path returned by icc_get()
 * @avg_bw: average bandwidth in kilobytes per second
 * @peak_bw: peak bandwidth in kilobytes per second
 *
 * This function is used by an interconnect consumer to express its own needs
 * in terms of bandwidth for a previously requested path between two endpoints.
 * The requests are aggregated and each node is updated accordingly. The entire
 * path is locked by a mutex to ensure that the set() is completed.
 * The @path can be NULL when the "interconnects" DT properties is missing,
 * which will mean that no constraints will be set.
 *
 * Returns 0 on success, or an appropriate error code otherwise.
 */
int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
{
	struct icc_node *node;
	u32 old_avg, old_peak;
	size_t i;
	int ret;

	if (!path || !path->num_nodes)
		return 0;

	mutex_lock(&icc_lock);

	old_avg = path->reqs[0].avg_bw;
	old_peak = path->reqs[0].peak_bw;

	for (i = 0; i < path->num_nodes; i++) {
		node = path->reqs[i].node;

		/* update the consumer request for this path */
		path->reqs[i].avg_bw = avg_bw;
		path->reqs[i].peak_bw = peak_bw;

		/* aggregate requests for this node */
		aggregate_requests(node);
	}

	ret = apply_constraints(path);
	if (ret) {
		pr_debug("interconnect: error applying constraints (%d)\n",
			 ret);

		for (i = 0; i < path->num_nodes; i++) {
			node = path->reqs[i].node;
			path->reqs[i].avg_bw = old_avg;
			path->reqs[i].peak_bw = old_peak;
			aggregate_requests(node);
		}
		apply_constraints(path);
	}

	mutex_unlock(&icc_lock);

	return ret;
}
EXPORT_SYMBOL_GPL(icc_set_bw);

/**
 * icc_get() - return a handle for path between two endpoints
 * @dev: the device requesting the path
 * @src_id: source device port id
 * @dst_id: destination device port id
 *
 * This function will search for a path between two endpoints and return an
 * icc_path handle on success. Use icc_put() to release
 * constraints when they are not needed anymore.
 * If the interconnect API is disabled, NULL is returned and the consumer
 * drivers will still build. Drivers are free to handle this specifically,
 * but they don't have to.
 *
 * Return: icc_path pointer on success, ERR_PTR() on error or NULL if the
 * interconnect API is disabled.
 */
struct icc_path *icc_get(struct device *dev, const int src_id, const int dst_id)
{
	struct icc_node *src, *dst;
	struct icc_path *path = ERR_PTR(-EPROBE_DEFER);

	mutex_lock(&icc_lock);

	src = node_find(src_id);
	if (!src)
		goto out;

	dst = node_find(dst_id);
	if (!dst)
		goto out;

	path = path_find(dev, src, dst);
	if (IS_ERR(path)) {
		dev_err(dev, "%s: invalid path=%ld\n", __func__, PTR_ERR(path));
		goto out;
	}

	path->name = kasprintf(GFP_KERNEL, "%s-%s", src->name, dst->name);
out:
	mutex_unlock(&icc_lock);
	return path;
}
EXPORT_SYMBOL_GPL(icc_get);

/**
 * icc_put() - release the reference to the icc_path
 * @path: interconnect path
 *
 * Use this function to release the constraints on a path when the path is
 * no longer needed. The constraints will be re-aggregated.
 */
void icc_put(struct icc_path *path)
{
	struct icc_node *node;
	size_t i;
	int ret;

	if (!path || WARN_ON(IS_ERR(path)))
		return;

	ret = icc_set_bw(path, 0, 0);
	if (ret)
		pr_err("%s: error (%d)\n", __func__, ret);

	mutex_lock(&icc_lock);
	for (i = 0; i < path->num_nodes; i++) {
		node = path->reqs[i].node;
		hlist_del(&path->reqs[i].req_node);
		if (!WARN_ON(!node->provider->users))
			node->provider->users--;
	}
	mutex_unlock(&icc_lock);

	kfree_const(path->name);
	kfree(path);
}
EXPORT_SYMBOL_GPL(icc_put);

static struct icc_node *icc_node_create_nolock(int id)
{
	struct icc_node *node;

	/* check if node already exists */
	node = node_find(id);
	if (node)
		return node;

	node = kzalloc(sizeof(*node), GFP_KERNEL);
	if (!node)
		return ERR_PTR(-ENOMEM);

	id = idr_alloc(&icc_idr, node, id, id + 1, GFP_KERNEL);
	if (id < 0) {
		WARN(1, "%s: couldn't get idr\n", __func__);
		kfree(node);
		return ERR_PTR(id);
	}

	node->id = id;

	return node;
}

/**
 * icc_node_create() - create a node
 * @id: node id
 *
 * Return: icc_node pointer on success, or ERR_PTR() on error
 */
struct icc_node *icc_node_create(int id)
{
	struct icc_node *node;

	mutex_lock(&icc_lock);

	node = icc_node_create_nolock(id);

	mutex_unlock(&icc_lock);

	return node;
}
EXPORT_SYMBOL_GPL(icc_node_create);

/**
 * icc_node_destroy() - destroy a node
 * @id: node id
 */
void icc_node_destroy(int id)
{
	struct icc_node *node;

	mutex_lock(&icc_lock);

	node = node_find(id);
	if (node) {
		idr_remove(&icc_idr, node->id);
		WARN_ON(!hlist_empty(&node->req_list));
	}

	mutex_unlock(&icc_lock);

	kfree(node);
}
EXPORT_SYMBOL_GPL(icc_node_destroy);

/**
 * icc_link_create() - create a link between two nodes
 * @node: source node id
 * @dst_id: destination node id
 *
 * Create a link between two nodes. The nodes might belong to different
 * interconnect providers and the @dst_id node might not exist (if the
 * provider driver has not probed yet). So just create the @dst_id node
 * and when the actual provider driver is probed, the rest of the node
 * data is filled.
 *
 * Return: 0 on success, or an error code otherwise
 */
int icc_link_create(struct icc_node *node, const int dst_id)
{
	struct icc_node *dst;
	struct icc_node **new;
	int ret = 0;

	if (!node->provider)
		return -EINVAL;

	mutex_lock(&icc_lock);

	dst = node_find(dst_id);
	if (!dst) {
		dst = icc_node_create_nolock(dst_id);

		if (IS_ERR(dst)) {
			ret = PTR_ERR(dst);
			goto out;
		}
	}

	new = krealloc(node->links,
		       (node->num_links + 1) * sizeof(*node->links),
		       GFP_KERNEL);
	if (!new) {
		ret = -ENOMEM;
		goto out;
	}

	node->links = new;
	node->links[node->num_links++] = dst;

out:
	mutex_unlock(&icc_lock);

	return ret;
}
EXPORT_SYMBOL_GPL(icc_link_create);

/**
 * icc_link_destroy() - destroy a link between two nodes
 * @src: pointer to source node
 * @dst: pointer to destination node
 *
 * Return: 0 on success, or an error code otherwise
 */
int icc_link_destroy(struct icc_node *src, struct icc_node *dst)
{
	struct icc_node **new;
	size_t slot;
	int ret = 0;

	if (IS_ERR_OR_NULL(src))
		return -EINVAL;

	if (IS_ERR_OR_NULL(dst))
		return -EINVAL;

	mutex_lock(&icc_lock);

	for (slot = 0; slot < src->num_links; slot++)
		if (src->links[slot] == dst)
			break;

	if (WARN_ON(slot == src->num_links)) {
		ret = -ENXIO;
		goto out;
	}

	src->links[slot] = src->links[--src->num_links];

	new = krealloc(src->links, src->num_links * sizeof(*src->links),
		       GFP_KERNEL);
	if (new)
		src->links = new;

out:
	mutex_unlock(&icc_lock);

	return ret;
}
EXPORT_SYMBOL_GPL(icc_link_destroy);

/**
 * icc_node_add() - add interconnect node to interconnect provider
 * @node: pointer to the interconnect node
 * @provider: pointer to the interconnect provider
 */
void icc_node_add(struct icc_node *node, struct icc_provider *provider)
{
	mutex_lock(&icc_lock);

	node->provider = provider;
	list_add_tail(&node->node_list, &provider->nodes);

	mutex_unlock(&icc_lock);
}
EXPORT_SYMBOL_GPL(icc_node_add);

/**
 * icc_node_del() - delete interconnect node from interconnect provider
 * @node: pointer to the interconnect node
 */
void icc_node_del(struct icc_node *node)
{
	mutex_lock(&icc_lock);

	list_del(&node->node_list);

	mutex_unlock(&icc_lock);
}
EXPORT_SYMBOL_GPL(icc_node_del);

/**
 * icc_nodes_remove() - remove all previously added nodes from provider
 * @provider: the interconnect provider we are removing nodes from
 *
 * Return: 0 on success, or an error code otherwise
 */
int icc_nodes_remove(struct icc_provider *provider)
{
	struct icc_node *n, *tmp;

	if (WARN_ON(IS_ERR_OR_NULL(provider)))
		return -EINVAL;

	list_for_each_entry_safe_reverse(n, tmp, &provider->nodes, node_list) {
		icc_node_del(n);
		icc_node_destroy(n->id);
	}

	return 0;
}
EXPORT_SYMBOL_GPL(icc_nodes_remove);

/**
 * icc_provider_add() - add a new interconnect provider
 * @provider: the interconnect provider that will be added into topology
 *
 * Return: 0 on success, or an error code otherwise
 */
int icc_provider_add(struct icc_provider *provider)
{
	if (WARN_ON(!provider->set))
		return -EINVAL;
	if (WARN_ON(!provider->xlate))
		return -EINVAL;

	mutex_lock(&icc_lock);

	INIT_LIST_HEAD(&provider->nodes);
	list_add_tail(&provider->provider_list, &icc_providers);

	mutex_unlock(&icc_lock);

	dev_dbg(provider->dev, "interconnect provider added to topology\n");

	return 0;
}
EXPORT_SYMBOL_GPL(icc_provider_add);

/**
 * icc_provider_del() - delete previously added interconnect provider
 * @provider: the interconnect provider that will be removed from topology
 *
 * Return: 0 on success, or an error code otherwise
 */
int icc_provider_del(struct icc_provider *provider)
{
	mutex_lock(&icc_lock);
	if (provider->users) {
		pr_warn("interconnect provider still has %d users\n",
			provider->users);
		mutex_unlock(&icc_lock);
		return -EBUSY;
	}

	if (!list_empty(&provider->nodes)) {
		pr_warn("interconnect provider still has nodes\n");
		mutex_unlock(&icc_lock);
		return -EBUSY;
	}

	list_del(&provider->provider_list);
	mutex_unlock(&icc_lock);

	return 0;
}
EXPORT_SYMBOL_GPL(icc_provider_del);

static int __init icc_init(void)
{
	icc_debugfs_dir = debugfs_create_dir("interconnect", NULL);
	debugfs_create_file("interconnect_summary", 0444,
			    icc_debugfs_dir, NULL, &icc_summary_fops);
	return 0;
}

static void __exit icc_exit(void)
{
	debugfs_remove_recursive(icc_debugfs_dir);
}
module_init(icc_init);
module_exit(icc_exit);

MODULE_AUTHOR("Georgi Djakov <georgi.djakov@linaro.org>");
MODULE_DESCRIPTION("Interconnect Driver Core");
MODULE_LICENSE("GPL v2");