Loading...
Note: File does not exist in v3.1.
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Interconnect framework core driver
4 *
5 * Copyright (c) 2017-2019, Linaro Ltd.
6 * Author: Georgi Djakov <georgi.djakov@linaro.org>
7 */
8
9#include <linux/debugfs.h>
10#include <linux/device.h>
11#include <linux/idr.h>
12#include <linux/init.h>
13#include <linux/interconnect.h>
14#include <linux/interconnect-provider.h>
15#include <linux/list.h>
16#include <linux/module.h>
17#include <linux/mutex.h>
18#include <linux/slab.h>
19#include <linux/of.h>
20#include <linux/overflow.h>
21
22static DEFINE_IDR(icc_idr);
23static LIST_HEAD(icc_providers);
24static DEFINE_MUTEX(icc_lock);
25static struct dentry *icc_debugfs_dir;
26
27/**
28 * struct icc_req - constraints that are attached to each node
29 * @req_node: entry in list of requests for the particular @node
30 * @node: the interconnect node to which this constraint applies
31 * @dev: reference to the device that sets the constraints
32 * @tag: path tag (optional)
33 * @avg_bw: an integer describing the average bandwidth in kBps
34 * @peak_bw: an integer describing the peak bandwidth in kBps
35 */
36struct icc_req {
37 struct hlist_node req_node;
38 struct icc_node *node;
39 struct device *dev;
40 u32 tag;
41 u32 avg_bw;
42 u32 peak_bw;
43};
44
45/**
46 * struct icc_path - interconnect path structure
47 * @num_nodes: number of hops (nodes)
48 * @reqs: array of the requests applicable to this path of nodes
49 */
50struct icc_path {
51 size_t num_nodes;
52 struct icc_req reqs[];
53};
54
55static void icc_summary_show_one(struct seq_file *s, struct icc_node *n)
56{
57 if (!n)
58 return;
59
60 seq_printf(s, "%-30s %12u %12u\n",
61 n->name, n->avg_bw, n->peak_bw);
62}
63
64static int icc_summary_show(struct seq_file *s, void *data)
65{
66 struct icc_provider *provider;
67
68 seq_puts(s, " node avg peak\n");
69 seq_puts(s, "--------------------------------------------------------\n");
70
71 mutex_lock(&icc_lock);
72
73 list_for_each_entry(provider, &icc_providers, provider_list) {
74 struct icc_node *n;
75
76 list_for_each_entry(n, &provider->nodes, node_list) {
77 struct icc_req *r;
78
79 icc_summary_show_one(s, n);
80 hlist_for_each_entry(r, &n->req_list, req_node) {
81 if (!r->dev)
82 continue;
83
84 seq_printf(s, " %-26s %12u %12u\n",
85 dev_name(r->dev), r->avg_bw,
86 r->peak_bw);
87 }
88 }
89 }
90
91 mutex_unlock(&icc_lock);
92
93 return 0;
94}
95DEFINE_SHOW_ATTRIBUTE(icc_summary);
96
97static struct icc_node *node_find(const int id)
98{
99 return idr_find(&icc_idr, id);
100}
101
102static struct icc_path *path_init(struct device *dev, struct icc_node *dst,
103 ssize_t num_nodes)
104{
105 struct icc_node *node = dst;
106 struct icc_path *path;
107 int i;
108
109 path = kzalloc(struct_size(path, reqs, num_nodes), GFP_KERNEL);
110 if (!path)
111 return ERR_PTR(-ENOMEM);
112
113 path->num_nodes = num_nodes;
114
115 for (i = num_nodes - 1; i >= 0; i--) {
116 node->provider->users++;
117 hlist_add_head(&path->reqs[i].req_node, &node->req_list);
118 path->reqs[i].node = node;
119 path->reqs[i].dev = dev;
120 /* reference to previous node was saved during path traversal */
121 node = node->reverse;
122 }
123
124 return path;
125}
126
127static struct icc_path *path_find(struct device *dev, struct icc_node *src,
128 struct icc_node *dst)
129{
130 struct icc_path *path = ERR_PTR(-EPROBE_DEFER);
131 struct icc_node *n, *node = NULL;
132 struct list_head traverse_list;
133 struct list_head edge_list;
134 struct list_head visited_list;
135 size_t i, depth = 1;
136 bool found = false;
137
138 INIT_LIST_HEAD(&traverse_list);
139 INIT_LIST_HEAD(&edge_list);
140 INIT_LIST_HEAD(&visited_list);
141
142 list_add(&src->search_list, &traverse_list);
143 src->reverse = NULL;
144
145 do {
146 list_for_each_entry_safe(node, n, &traverse_list, search_list) {
147 if (node == dst) {
148 found = true;
149 list_splice_init(&edge_list, &visited_list);
150 list_splice_init(&traverse_list, &visited_list);
151 break;
152 }
153 for (i = 0; i < node->num_links; i++) {
154 struct icc_node *tmp = node->links[i];
155
156 if (!tmp) {
157 path = ERR_PTR(-ENOENT);
158 goto out;
159 }
160
161 if (tmp->is_traversed)
162 continue;
163
164 tmp->is_traversed = true;
165 tmp->reverse = node;
166 list_add_tail(&tmp->search_list, &edge_list);
167 }
168 }
169
170 if (found)
171 break;
172
173 list_splice_init(&traverse_list, &visited_list);
174 list_splice_init(&edge_list, &traverse_list);
175
176 /* count the hops including the source */
177 depth++;
178
179 } while (!list_empty(&traverse_list));
180
181out:
182
183 /* reset the traversed state */
184 list_for_each_entry_reverse(n, &visited_list, search_list)
185 n->is_traversed = false;
186
187 if (found)
188 path = path_init(dev, dst, depth);
189
190 return path;
191}
192
193/*
194 * We want the path to honor all bandwidth requests, so the average and peak
195 * bandwidth requirements from each consumer are aggregated at each node.
196 * The aggregation is platform specific, so each platform can customize it by
197 * implementing its own aggregate() function.
198 */
199
200static int aggregate_requests(struct icc_node *node)
201{
202 struct icc_provider *p = node->provider;
203 struct icc_req *r;
204
205 node->avg_bw = 0;
206 node->peak_bw = 0;
207
208 if (p->pre_aggregate)
209 p->pre_aggregate(node);
210
211 hlist_for_each_entry(r, &node->req_list, req_node)
212 p->aggregate(node, r->tag, r->avg_bw, r->peak_bw,
213 &node->avg_bw, &node->peak_bw);
214
215 return 0;
216}
217
218static int apply_constraints(struct icc_path *path)
219{
220 struct icc_node *next, *prev = NULL;
221 int ret = -EINVAL;
222 int i;
223
224 for (i = 0; i < path->num_nodes; i++) {
225 next = path->reqs[i].node;
226
227 /*
228 * Both endpoints should be valid master-slave pairs of the
229 * same interconnect provider that will be configured.
230 */
231 if (!prev || next->provider != prev->provider) {
232 prev = next;
233 continue;
234 }
235
236 /* set the constraints */
237 ret = next->provider->set(prev, next);
238 if (ret)
239 goto out;
240
241 prev = next;
242 }
243out:
244 return ret;
245}
246
247/* of_icc_xlate_onecell() - Translate function using a single index.
248 * @spec: OF phandle args to map into an interconnect node.
249 * @data: private data (pointer to struct icc_onecell_data)
250 *
251 * This is a generic translate function that can be used to model simple
252 * interconnect providers that have one device tree node and provide
253 * multiple interconnect nodes. A single cell is used as an index into
254 * an array of icc nodes specified in the icc_onecell_data struct when
255 * registering the provider.
256 */
257struct icc_node *of_icc_xlate_onecell(struct of_phandle_args *spec,
258 void *data)
259{
260 struct icc_onecell_data *icc_data = data;
261 unsigned int idx = spec->args[0];
262
263 if (idx >= icc_data->num_nodes) {
264 pr_err("%s: invalid index %u\n", __func__, idx);
265 return ERR_PTR(-EINVAL);
266 }
267
268 return icc_data->nodes[idx];
269}
270EXPORT_SYMBOL_GPL(of_icc_xlate_onecell);
271
272/**
273 * of_icc_get_from_provider() - Look-up interconnect node
274 * @spec: OF phandle args to use for look-up
275 *
276 * Looks for interconnect provider under the node specified by @spec and if
277 * found, uses xlate function of the provider to map phandle args to node.
278 *
279 * Returns a valid pointer to struct icc_node on success or ERR_PTR()
280 * on failure.
281 */
282static struct icc_node *of_icc_get_from_provider(struct of_phandle_args *spec)
283{
284 struct icc_node *node = ERR_PTR(-EPROBE_DEFER);
285 struct icc_provider *provider;
286
287 if (!spec || spec->args_count != 1)
288 return ERR_PTR(-EINVAL);
289
290 mutex_lock(&icc_lock);
291 list_for_each_entry(provider, &icc_providers, provider_list) {
292 if (provider->dev->of_node == spec->np)
293 node = provider->xlate(spec, provider->data);
294 if (!IS_ERR(node))
295 break;
296 }
297 mutex_unlock(&icc_lock);
298
299 return node;
300}
301
302/**
303 * of_icc_get() - get a path handle from a DT node based on name
304 * @dev: device pointer for the consumer device
305 * @name: interconnect path name
306 *
307 * This function will search for a path between two endpoints and return an
308 * icc_path handle on success. Use icc_put() to release constraints when they
309 * are not needed anymore.
310 * If the interconnect API is disabled, NULL is returned and the consumer
311 * drivers will still build. Drivers are free to handle this specifically,
312 * but they don't have to.
313 *
314 * Return: icc_path pointer on success or ERR_PTR() on error. NULL is returned
315 * when the API is disabled or the "interconnects" DT property is missing.
316 */
317struct icc_path *of_icc_get(struct device *dev, const char *name)
318{
319 struct icc_path *path = ERR_PTR(-EPROBE_DEFER);
320 struct icc_node *src_node, *dst_node;
321 struct device_node *np = NULL;
322 struct of_phandle_args src_args, dst_args;
323 int idx = 0;
324 int ret;
325
326 if (!dev || !dev->of_node)
327 return ERR_PTR(-ENODEV);
328
329 np = dev->of_node;
330
331 /*
332 * When the consumer DT node do not have "interconnects" property
333 * return a NULL path to skip setting constraints.
334 */
335 if (!of_find_property(np, "interconnects", NULL))
336 return NULL;
337
338 /*
339 * We use a combination of phandle and specifier for endpoint. For now
340 * lets support only global ids and extend this in the future if needed
341 * without breaking DT compatibility.
342 */
343 if (name) {
344 idx = of_property_match_string(np, "interconnect-names", name);
345 if (idx < 0)
346 return ERR_PTR(idx);
347 }
348
349 ret = of_parse_phandle_with_args(np, "interconnects",
350 "#interconnect-cells", idx * 2,
351 &src_args);
352 if (ret)
353 return ERR_PTR(ret);
354
355 of_node_put(src_args.np);
356
357 ret = of_parse_phandle_with_args(np, "interconnects",
358 "#interconnect-cells", idx * 2 + 1,
359 &dst_args);
360 if (ret)
361 return ERR_PTR(ret);
362
363 of_node_put(dst_args.np);
364
365 src_node = of_icc_get_from_provider(&src_args);
366
367 if (IS_ERR(src_node)) {
368 if (PTR_ERR(src_node) != -EPROBE_DEFER)
369 dev_err(dev, "error finding src node: %ld\n",
370 PTR_ERR(src_node));
371 return ERR_CAST(src_node);
372 }
373
374 dst_node = of_icc_get_from_provider(&dst_args);
375
376 if (IS_ERR(dst_node)) {
377 if (PTR_ERR(dst_node) != -EPROBE_DEFER)
378 dev_err(dev, "error finding dst node: %ld\n",
379 PTR_ERR(dst_node));
380 return ERR_CAST(dst_node);
381 }
382
383 mutex_lock(&icc_lock);
384 path = path_find(dev, src_node, dst_node);
385 if (IS_ERR(path))
386 dev_err(dev, "%s: invalid path=%ld\n", __func__, PTR_ERR(path));
387 mutex_unlock(&icc_lock);
388
389 return path;
390}
391EXPORT_SYMBOL_GPL(of_icc_get);
392
393/**
394 * icc_set_tag() - set an optional tag on a path
395 * @path: the path we want to tag
396 * @tag: the tag value
397 *
398 * This function allows consumers to append a tag to the requests associated
399 * with a path, so that a different aggregation could be done based on this tag.
400 */
401void icc_set_tag(struct icc_path *path, u32 tag)
402{
403 int i;
404
405 if (!path)
406 return;
407
408 mutex_lock(&icc_lock);
409
410 for (i = 0; i < path->num_nodes; i++)
411 path->reqs[i].tag = tag;
412
413 mutex_unlock(&icc_lock);
414}
415EXPORT_SYMBOL_GPL(icc_set_tag);
416
417/**
418 * icc_set_bw() - set bandwidth constraints on an interconnect path
419 * @path: reference to the path returned by icc_get()
420 * @avg_bw: average bandwidth in kilobytes per second
421 * @peak_bw: peak bandwidth in kilobytes per second
422 *
423 * This function is used by an interconnect consumer to express its own needs
424 * in terms of bandwidth for a previously requested path between two endpoints.
425 * The requests are aggregated and each node is updated accordingly. The entire
426 * path is locked by a mutex to ensure that the set() is completed.
427 * The @path can be NULL when the "interconnects" DT properties is missing,
428 * which will mean that no constraints will be set.
429 *
430 * Returns 0 on success, or an appropriate error code otherwise.
431 */
432int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
433{
434 struct icc_node *node;
435 u32 old_avg, old_peak;
436 size_t i;
437 int ret;
438
439 if (!path || !path->num_nodes)
440 return 0;
441
442 mutex_lock(&icc_lock);
443
444 old_avg = path->reqs[0].avg_bw;
445 old_peak = path->reqs[0].peak_bw;
446
447 for (i = 0; i < path->num_nodes; i++) {
448 node = path->reqs[i].node;
449
450 /* update the consumer request for this path */
451 path->reqs[i].avg_bw = avg_bw;
452 path->reqs[i].peak_bw = peak_bw;
453
454 /* aggregate requests for this node */
455 aggregate_requests(node);
456 }
457
458 ret = apply_constraints(path);
459 if (ret) {
460 pr_debug("interconnect: error applying constraints (%d)\n",
461 ret);
462
463 for (i = 0; i < path->num_nodes; i++) {
464 node = path->reqs[i].node;
465 path->reqs[i].avg_bw = old_avg;
466 path->reqs[i].peak_bw = old_peak;
467 aggregate_requests(node);
468 }
469 apply_constraints(path);
470 }
471
472 mutex_unlock(&icc_lock);
473
474 return ret;
475}
476EXPORT_SYMBOL_GPL(icc_set_bw);
477
478/**
479 * icc_get() - return a handle for path between two endpoints
480 * @dev: the device requesting the path
481 * @src_id: source device port id
482 * @dst_id: destination device port id
483 *
484 * This function will search for a path between two endpoints and return an
485 * icc_path handle on success. Use icc_put() to release
486 * constraints when they are not needed anymore.
487 * If the interconnect API is disabled, NULL is returned and the consumer
488 * drivers will still build. Drivers are free to handle this specifically,
489 * but they don't have to.
490 *
491 * Return: icc_path pointer on success, ERR_PTR() on error or NULL if the
492 * interconnect API is disabled.
493 */
494struct icc_path *icc_get(struct device *dev, const int src_id, const int dst_id)
495{
496 struct icc_node *src, *dst;
497 struct icc_path *path = ERR_PTR(-EPROBE_DEFER);
498
499 mutex_lock(&icc_lock);
500
501 src = node_find(src_id);
502 if (!src)
503 goto out;
504
505 dst = node_find(dst_id);
506 if (!dst)
507 goto out;
508
509 path = path_find(dev, src, dst);
510 if (IS_ERR(path))
511 dev_err(dev, "%s: invalid path=%ld\n", __func__, PTR_ERR(path));
512
513out:
514 mutex_unlock(&icc_lock);
515 return path;
516}
517EXPORT_SYMBOL_GPL(icc_get);
518
519/**
520 * icc_put() - release the reference to the icc_path
521 * @path: interconnect path
522 *
523 * Use this function to release the constraints on a path when the path is
524 * no longer needed. The constraints will be re-aggregated.
525 */
526void icc_put(struct icc_path *path)
527{
528 struct icc_node *node;
529 size_t i;
530 int ret;
531
532 if (!path || WARN_ON(IS_ERR(path)))
533 return;
534
535 ret = icc_set_bw(path, 0, 0);
536 if (ret)
537 pr_err("%s: error (%d)\n", __func__, ret);
538
539 mutex_lock(&icc_lock);
540 for (i = 0; i < path->num_nodes; i++) {
541 node = path->reqs[i].node;
542 hlist_del(&path->reqs[i].req_node);
543 if (!WARN_ON(!node->provider->users))
544 node->provider->users--;
545 }
546 mutex_unlock(&icc_lock);
547
548 kfree(path);
549}
550EXPORT_SYMBOL_GPL(icc_put);
551
552static struct icc_node *icc_node_create_nolock(int id)
553{
554 struct icc_node *node;
555
556 /* check if node already exists */
557 node = node_find(id);
558 if (node)
559 return node;
560
561 node = kzalloc(sizeof(*node), GFP_KERNEL);
562 if (!node)
563 return ERR_PTR(-ENOMEM);
564
565 id = idr_alloc(&icc_idr, node, id, id + 1, GFP_KERNEL);
566 if (id < 0) {
567 WARN(1, "%s: couldn't get idr\n", __func__);
568 kfree(node);
569 return ERR_PTR(id);
570 }
571
572 node->id = id;
573
574 return node;
575}
576
577/**
578 * icc_node_create() - create a node
579 * @id: node id
580 *
581 * Return: icc_node pointer on success, or ERR_PTR() on error
582 */
583struct icc_node *icc_node_create(int id)
584{
585 struct icc_node *node;
586
587 mutex_lock(&icc_lock);
588
589 node = icc_node_create_nolock(id);
590
591 mutex_unlock(&icc_lock);
592
593 return node;
594}
595EXPORT_SYMBOL_GPL(icc_node_create);
596
597/**
598 * icc_node_destroy() - destroy a node
599 * @id: node id
600 */
601void icc_node_destroy(int id)
602{
603 struct icc_node *node;
604
605 mutex_lock(&icc_lock);
606
607 node = node_find(id);
608 if (node) {
609 idr_remove(&icc_idr, node->id);
610 WARN_ON(!hlist_empty(&node->req_list));
611 }
612
613 mutex_unlock(&icc_lock);
614
615 kfree(node);
616}
617EXPORT_SYMBOL_GPL(icc_node_destroy);
618
619/**
620 * icc_link_create() - create a link between two nodes
621 * @node: source node id
622 * @dst_id: destination node id
623 *
624 * Create a link between two nodes. The nodes might belong to different
625 * interconnect providers and the @dst_id node might not exist (if the
626 * provider driver has not probed yet). So just create the @dst_id node
627 * and when the actual provider driver is probed, the rest of the node
628 * data is filled.
629 *
630 * Return: 0 on success, or an error code otherwise
631 */
632int icc_link_create(struct icc_node *node, const int dst_id)
633{
634 struct icc_node *dst;
635 struct icc_node **new;
636 int ret = 0;
637
638 if (!node->provider)
639 return -EINVAL;
640
641 mutex_lock(&icc_lock);
642
643 dst = node_find(dst_id);
644 if (!dst) {
645 dst = icc_node_create_nolock(dst_id);
646
647 if (IS_ERR(dst)) {
648 ret = PTR_ERR(dst);
649 goto out;
650 }
651 }
652
653 new = krealloc(node->links,
654 (node->num_links + 1) * sizeof(*node->links),
655 GFP_KERNEL);
656 if (!new) {
657 ret = -ENOMEM;
658 goto out;
659 }
660
661 node->links = new;
662 node->links[node->num_links++] = dst;
663
664out:
665 mutex_unlock(&icc_lock);
666
667 return ret;
668}
669EXPORT_SYMBOL_GPL(icc_link_create);
670
671/**
672 * icc_link_destroy() - destroy a link between two nodes
673 * @src: pointer to source node
674 * @dst: pointer to destination node
675 *
676 * Return: 0 on success, or an error code otherwise
677 */
678int icc_link_destroy(struct icc_node *src, struct icc_node *dst)
679{
680 struct icc_node **new;
681 size_t slot;
682 int ret = 0;
683
684 if (IS_ERR_OR_NULL(src))
685 return -EINVAL;
686
687 if (IS_ERR_OR_NULL(dst))
688 return -EINVAL;
689
690 mutex_lock(&icc_lock);
691
692 for (slot = 0; slot < src->num_links; slot++)
693 if (src->links[slot] == dst)
694 break;
695
696 if (WARN_ON(slot == src->num_links)) {
697 ret = -ENXIO;
698 goto out;
699 }
700
701 src->links[slot] = src->links[--src->num_links];
702
703 new = krealloc(src->links, src->num_links * sizeof(*src->links),
704 GFP_KERNEL);
705 if (new)
706 src->links = new;
707
708out:
709 mutex_unlock(&icc_lock);
710
711 return ret;
712}
713EXPORT_SYMBOL_GPL(icc_link_destroy);
714
715/**
716 * icc_node_add() - add interconnect node to interconnect provider
717 * @node: pointer to the interconnect node
718 * @provider: pointer to the interconnect provider
719 */
720void icc_node_add(struct icc_node *node, struct icc_provider *provider)
721{
722 mutex_lock(&icc_lock);
723
724 node->provider = provider;
725 list_add_tail(&node->node_list, &provider->nodes);
726
727 mutex_unlock(&icc_lock);
728}
729EXPORT_SYMBOL_GPL(icc_node_add);
730
731/**
732 * icc_node_del() - delete interconnect node from interconnect provider
733 * @node: pointer to the interconnect node
734 */
735void icc_node_del(struct icc_node *node)
736{
737 mutex_lock(&icc_lock);
738
739 list_del(&node->node_list);
740
741 mutex_unlock(&icc_lock);
742}
743EXPORT_SYMBOL_GPL(icc_node_del);
744
745/**
746 * icc_provider_add() - add a new interconnect provider
747 * @provider: the interconnect provider that will be added into topology
748 *
749 * Return: 0 on success, or an error code otherwise
750 */
751int icc_provider_add(struct icc_provider *provider)
752{
753 if (WARN_ON(!provider->set))
754 return -EINVAL;
755 if (WARN_ON(!provider->xlate))
756 return -EINVAL;
757
758 mutex_lock(&icc_lock);
759
760 INIT_LIST_HEAD(&provider->nodes);
761 list_add_tail(&provider->provider_list, &icc_providers);
762
763 mutex_unlock(&icc_lock);
764
765 dev_dbg(provider->dev, "interconnect provider added to topology\n");
766
767 return 0;
768}
769EXPORT_SYMBOL_GPL(icc_provider_add);
770
771/**
772 * icc_provider_del() - delete previously added interconnect provider
773 * @provider: the interconnect provider that will be removed from topology
774 *
775 * Return: 0 on success, or an error code otherwise
776 */
777int icc_provider_del(struct icc_provider *provider)
778{
779 mutex_lock(&icc_lock);
780 if (provider->users) {
781 pr_warn("interconnect provider still has %d users\n",
782 provider->users);
783 mutex_unlock(&icc_lock);
784 return -EBUSY;
785 }
786
787 if (!list_empty(&provider->nodes)) {
788 pr_warn("interconnect provider still has nodes\n");
789 mutex_unlock(&icc_lock);
790 return -EBUSY;
791 }
792
793 list_del(&provider->provider_list);
794 mutex_unlock(&icc_lock);
795
796 return 0;
797}
798EXPORT_SYMBOL_GPL(icc_provider_del);
799
800static int __init icc_init(void)
801{
802 icc_debugfs_dir = debugfs_create_dir("interconnect", NULL);
803 debugfs_create_file("interconnect_summary", 0444,
804 icc_debugfs_dir, NULL, &icc_summary_fops);
805 return 0;
806}
807
808static void __exit icc_exit(void)
809{
810 debugfs_remove_recursive(icc_debugfs_dir);
811}
812module_init(icc_init);
813module_exit(icc_exit);
814
815MODULE_AUTHOR("Georgi Djakov <georgi.djakov@linaro.org>");
816MODULE_DESCRIPTION("Interconnect Driver Core");
817MODULE_LICENSE("GPL v2");