1 // SPDX-License-Identifier: GPL-2.0
3 * Interconnect framework core driver
5 * Copyright (c) 2017-2019, Linaro Ltd.
6 * Author: Georgi Djakov <georgi.djakov@linaro.org>
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>
20 #include <linux/overflow.h>
22 static DEFINE_IDR(icc_idr);
23 static LIST_HEAD(icc_providers);
24 static DEFINE_MUTEX(icc_lock);
25 static struct dentry *icc_debugfs_dir;
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
37 struct hlist_node req_node;
38 struct icc_node *node;
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
52 struct icc_req reqs[];
55 static void icc_summary_show_one(struct seq_file *s, struct icc_node *n)
60 seq_printf(s, "%-30s %12u %12u\n",
61 n->name, n->avg_bw, n->peak_bw);
64 static int icc_summary_show(struct seq_file *s, void *data)
66 struct icc_provider *provider;
68 seq_puts(s, " node avg peak\n");
69 seq_puts(s, "--------------------------------------------------------\n");
71 mutex_lock(&icc_lock);
73 list_for_each_entry(provider, &icc_providers, provider_list) {
76 list_for_each_entry(n, &provider->nodes, node_list) {
79 icc_summary_show_one(s, n);
80 hlist_for_each_entry(r, &n->req_list, req_node) {
84 seq_printf(s, " %-26s %12u %12u\n",
85 dev_name(r->dev), r->avg_bw,
91 mutex_unlock(&icc_lock);
95 DEFINE_SHOW_ATTRIBUTE(icc_summary);
97 static struct icc_node *node_find(const int id)
99 return idr_find(&icc_idr, id);
102 static struct icc_path *path_init(struct device *dev, struct icc_node *dst,
105 struct icc_node *node = dst;
106 struct icc_path *path;
109 path = kzalloc(struct_size(path, reqs, num_nodes), GFP_KERNEL);
111 return ERR_PTR(-ENOMEM);
113 path->num_nodes = num_nodes;
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;
127 static struct icc_path *path_find(struct device *dev, struct icc_node *src,
128 struct icc_node *dst)
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;
138 INIT_LIST_HEAD(&traverse_list);
139 INIT_LIST_HEAD(&edge_list);
140 INIT_LIST_HEAD(&visited_list);
142 list_add(&src->search_list, &traverse_list);
146 list_for_each_entry_safe(node, n, &traverse_list, search_list) {
149 list_splice_init(&edge_list, &visited_list);
150 list_splice_init(&traverse_list, &visited_list);
153 for (i = 0; i < node->num_links; i++) {
154 struct icc_node *tmp = node->links[i];
157 path = ERR_PTR(-ENOENT);
161 if (tmp->is_traversed)
164 tmp->is_traversed = true;
166 list_add_tail(&tmp->search_list, &edge_list);
173 list_splice_init(&traverse_list, &visited_list);
174 list_splice_init(&edge_list, &traverse_list);
176 /* count the hops including the source */
179 } while (!list_empty(&traverse_list));
183 /* reset the traversed state */
184 list_for_each_entry_reverse(n, &visited_list, search_list)
185 n->is_traversed = false;
188 path = path_init(dev, dst, depth);
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.
200 static int aggregate_requests(struct icc_node *node)
202 struct icc_provider *p = node->provider;
208 if (p->pre_aggregate)
209 p->pre_aggregate(node);
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);
218 static int apply_constraints(struct icc_path *path)
220 struct icc_node *next, *prev = NULL;
224 for (i = 0; i < path->num_nodes; i++) {
225 next = path->reqs[i].node;
228 * Both endpoints should be valid master-slave pairs of the
229 * same interconnect provider that will be configured.
231 if (!prev || next->provider != prev->provider) {
236 /* set the constraints */
237 ret = next->provider->set(prev, next);
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)
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.
257 struct icc_node *of_icc_xlate_onecell(struct of_phandle_args *spec,
260 struct icc_onecell_data *icc_data = data;
261 unsigned int idx = spec->args[0];
263 if (idx >= icc_data->num_nodes) {
264 pr_err("%s: invalid index %u\n", __func__, idx);
265 return ERR_PTR(-EINVAL);
268 return icc_data->nodes[idx];
270 EXPORT_SYMBOL_GPL(of_icc_xlate_onecell);
273 * of_icc_get_from_provider() - Look-up interconnect node
274 * @spec: OF phandle args to use for look-up
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.
279 * Returns a valid pointer to struct icc_node on success or ERR_PTR()
282 static struct icc_node *of_icc_get_from_provider(struct of_phandle_args *spec)
284 struct icc_node *node = ERR_PTR(-EPROBE_DEFER);
285 struct icc_provider *provider;
287 if (!spec || spec->args_count != 1)
288 return ERR_PTR(-EINVAL);
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);
297 mutex_unlock(&icc_lock);
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
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.
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.
317 struct icc_path *of_icc_get(struct device *dev, const char *name)
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;
326 if (!dev || !dev->of_node)
327 return ERR_PTR(-ENODEV);
332 * When the consumer DT node do not have "interconnects" property
333 * return a NULL path to skip setting constraints.
335 if (!of_find_property(np, "interconnects", NULL))
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.
344 idx = of_property_match_string(np, "interconnect-names", name);
349 ret = of_parse_phandle_with_args(np, "interconnects",
350 "#interconnect-cells", idx * 2,
355 of_node_put(src_args.np);
357 ret = of_parse_phandle_with_args(np, "interconnects",
358 "#interconnect-cells", idx * 2 + 1,
363 of_node_put(dst_args.np);
365 src_node = of_icc_get_from_provider(&src_args);
367 if (IS_ERR(src_node)) {
368 if (PTR_ERR(src_node) != -EPROBE_DEFER)
369 dev_err(dev, "error finding src node: %ld\n",
371 return ERR_CAST(src_node);
374 dst_node = of_icc_get_from_provider(&dst_args);
376 if (IS_ERR(dst_node)) {
377 if (PTR_ERR(dst_node) != -EPROBE_DEFER)
378 dev_err(dev, "error finding dst node: %ld\n",
380 return ERR_CAST(dst_node);
383 mutex_lock(&icc_lock);
384 path = path_find(dev, src_node, dst_node);
386 dev_err(dev, "%s: invalid path=%ld\n", __func__, PTR_ERR(path));
387 mutex_unlock(&icc_lock);
391 EXPORT_SYMBOL_GPL(of_icc_get);
394 * icc_set_tag() - set an optional tag on a path
395 * @path: the path we want to tag
396 * @tag: the tag value
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.
401 void icc_set_tag(struct icc_path *path, u32 tag)
408 for (i = 0; i < path->num_nodes; i++)
409 path->reqs[i].tag = tag;
411 EXPORT_SYMBOL_GPL(icc_set_tag);
414 * icc_set_bw() - set bandwidth constraints on an interconnect path
415 * @path: reference to the path returned by icc_get()
416 * @avg_bw: average bandwidth in kilobytes per second
417 * @peak_bw: peak bandwidth in kilobytes per second
419 * This function is used by an interconnect consumer to express its own needs
420 * in terms of bandwidth for a previously requested path between two endpoints.
421 * The requests are aggregated and each node is updated accordingly. The entire
422 * path is locked by a mutex to ensure that the set() is completed.
423 * The @path can be NULL when the "interconnects" DT properties is missing,
424 * which will mean that no constraints will be set.
426 * Returns 0 on success, or an appropriate error code otherwise.
428 int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
430 struct icc_node *node;
431 u32 old_avg, old_peak;
435 if (!path || !path->num_nodes)
438 mutex_lock(&icc_lock);
440 old_avg = path->reqs[0].avg_bw;
441 old_peak = path->reqs[0].peak_bw;
443 for (i = 0; i < path->num_nodes; i++) {
444 node = path->reqs[i].node;
446 /* update the consumer request for this path */
447 path->reqs[i].avg_bw = avg_bw;
448 path->reqs[i].peak_bw = peak_bw;
450 /* aggregate requests for this node */
451 aggregate_requests(node);
454 ret = apply_constraints(path);
456 pr_debug("interconnect: error applying constraints (%d)\n",
459 for (i = 0; i < path->num_nodes; i++) {
460 node = path->reqs[i].node;
461 path->reqs[i].avg_bw = old_avg;
462 path->reqs[i].peak_bw = old_peak;
463 aggregate_requests(node);
465 apply_constraints(path);
468 mutex_unlock(&icc_lock);
472 EXPORT_SYMBOL_GPL(icc_set_bw);
475 * icc_get() - return a handle for path between two endpoints
476 * @dev: the device requesting the path
477 * @src_id: source device port id
478 * @dst_id: destination device port id
480 * This function will search for a path between two endpoints and return an
481 * icc_path handle on success. Use icc_put() to release
482 * constraints when they are not needed anymore.
483 * If the interconnect API is disabled, NULL is returned and the consumer
484 * drivers will still build. Drivers are free to handle this specifically,
485 * but they don't have to.
487 * Return: icc_path pointer on success, ERR_PTR() on error or NULL if the
488 * interconnect API is disabled.
490 struct icc_path *icc_get(struct device *dev, const int src_id, const int dst_id)
492 struct icc_node *src, *dst;
493 struct icc_path *path = ERR_PTR(-EPROBE_DEFER);
495 mutex_lock(&icc_lock);
497 src = node_find(src_id);
501 dst = node_find(dst_id);
505 path = path_find(dev, src, dst);
507 dev_err(dev, "%s: invalid path=%ld\n", __func__, PTR_ERR(path));
510 mutex_unlock(&icc_lock);
513 EXPORT_SYMBOL_GPL(icc_get);
516 * icc_put() - release the reference to the icc_path
517 * @path: interconnect path
519 * Use this function to release the constraints on a path when the path is
520 * no longer needed. The constraints will be re-aggregated.
522 void icc_put(struct icc_path *path)
524 struct icc_node *node;
528 if (!path || WARN_ON(IS_ERR(path)))
531 ret = icc_set_bw(path, 0, 0);
533 pr_err("%s: error (%d)\n", __func__, ret);
535 mutex_lock(&icc_lock);
536 for (i = 0; i < path->num_nodes; i++) {
537 node = path->reqs[i].node;
538 hlist_del(&path->reqs[i].req_node);
539 if (!WARN_ON(!node->provider->users))
540 node->provider->users--;
542 mutex_unlock(&icc_lock);
546 EXPORT_SYMBOL_GPL(icc_put);
548 static struct icc_node *icc_node_create_nolock(int id)
550 struct icc_node *node;
552 /* check if node already exists */
553 node = node_find(id);
557 node = kzalloc(sizeof(*node), GFP_KERNEL);
559 return ERR_PTR(-ENOMEM);
561 id = idr_alloc(&icc_idr, node, id, id + 1, GFP_KERNEL);
563 WARN(1, "%s: couldn't get idr\n", __func__);
574 * icc_node_create() - create a node
577 * Return: icc_node pointer on success, or ERR_PTR() on error
579 struct icc_node *icc_node_create(int id)
581 struct icc_node *node;
583 mutex_lock(&icc_lock);
585 node = icc_node_create_nolock(id);
587 mutex_unlock(&icc_lock);
591 EXPORT_SYMBOL_GPL(icc_node_create);
594 * icc_node_destroy() - destroy a node
597 void icc_node_destroy(int id)
599 struct icc_node *node;
601 mutex_lock(&icc_lock);
603 node = node_find(id);
605 idr_remove(&icc_idr, node->id);
606 WARN_ON(!hlist_empty(&node->req_list));
609 mutex_unlock(&icc_lock);
613 EXPORT_SYMBOL_GPL(icc_node_destroy);
616 * icc_link_create() - create a link between two nodes
617 * @node: source node id
618 * @dst_id: destination node id
620 * Create a link between two nodes. The nodes might belong to different
621 * interconnect providers and the @dst_id node might not exist (if the
622 * provider driver has not probed yet). So just create the @dst_id node
623 * and when the actual provider driver is probed, the rest of the node
626 * Return: 0 on success, or an error code otherwise
628 int icc_link_create(struct icc_node *node, const int dst_id)
630 struct icc_node *dst;
631 struct icc_node **new;
637 mutex_lock(&icc_lock);
639 dst = node_find(dst_id);
641 dst = icc_node_create_nolock(dst_id);
649 new = krealloc(node->links,
650 (node->num_links + 1) * sizeof(*node->links),
658 node->links[node->num_links++] = dst;
661 mutex_unlock(&icc_lock);
665 EXPORT_SYMBOL_GPL(icc_link_create);
668 * icc_link_destroy() - destroy a link between two nodes
669 * @src: pointer to source node
670 * @dst: pointer to destination node
672 * Return: 0 on success, or an error code otherwise
674 int icc_link_destroy(struct icc_node *src, struct icc_node *dst)
676 struct icc_node **new;
680 if (IS_ERR_OR_NULL(src))
683 if (IS_ERR_OR_NULL(dst))
686 mutex_lock(&icc_lock);
688 for (slot = 0; slot < src->num_links; slot++)
689 if (src->links[slot] == dst)
692 if (WARN_ON(slot == src->num_links)) {
697 src->links[slot] = src->links[--src->num_links];
699 new = krealloc(src->links, src->num_links * sizeof(*src->links),
705 mutex_unlock(&icc_lock);
709 EXPORT_SYMBOL_GPL(icc_link_destroy);
712 * icc_node_add() - add interconnect node to interconnect provider
713 * @node: pointer to the interconnect node
714 * @provider: pointer to the interconnect provider
716 void icc_node_add(struct icc_node *node, struct icc_provider *provider)
718 mutex_lock(&icc_lock);
720 node->provider = provider;
721 list_add_tail(&node->node_list, &provider->nodes);
723 mutex_unlock(&icc_lock);
725 EXPORT_SYMBOL_GPL(icc_node_add);
728 * icc_node_del() - delete interconnect node from interconnect provider
729 * @node: pointer to the interconnect node
731 void icc_node_del(struct icc_node *node)
733 mutex_lock(&icc_lock);
735 list_del(&node->node_list);
737 mutex_unlock(&icc_lock);
739 EXPORT_SYMBOL_GPL(icc_node_del);
742 * icc_provider_add() - add a new interconnect provider
743 * @provider: the interconnect provider that will be added into topology
745 * Return: 0 on success, or an error code otherwise
747 int icc_provider_add(struct icc_provider *provider)
749 if (WARN_ON(!provider->set))
751 if (WARN_ON(!provider->xlate))
754 mutex_lock(&icc_lock);
756 INIT_LIST_HEAD(&provider->nodes);
757 list_add_tail(&provider->provider_list, &icc_providers);
759 mutex_unlock(&icc_lock);
761 dev_dbg(provider->dev, "interconnect provider added to topology\n");
765 EXPORT_SYMBOL_GPL(icc_provider_add);
768 * icc_provider_del() - delete previously added interconnect provider
769 * @provider: the interconnect provider that will be removed from topology
771 * Return: 0 on success, or an error code otherwise
773 int icc_provider_del(struct icc_provider *provider)
775 mutex_lock(&icc_lock);
776 if (provider->users) {
777 pr_warn("interconnect provider still has %d users\n",
779 mutex_unlock(&icc_lock);
783 if (!list_empty(&provider->nodes)) {
784 pr_warn("interconnect provider still has nodes\n");
785 mutex_unlock(&icc_lock);
789 list_del(&provider->provider_list);
790 mutex_unlock(&icc_lock);
794 EXPORT_SYMBOL_GPL(icc_provider_del);
796 static int __init icc_init(void)
798 icc_debugfs_dir = debugfs_create_dir("interconnect", NULL);
799 debugfs_create_file("interconnect_summary", 0444,
800 icc_debugfs_dir, NULL, &icc_summary_fops);
804 static void __exit icc_exit(void)
806 debugfs_remove_recursive(icc_debugfs_dir);
808 module_init(icc_init);
809 module_exit(icc_exit);
811 MODULE_AUTHOR("Georgi Djakov <georgi.djakov@linaro.org>");
812 MODULE_DESCRIPTION("Interconnect Driver Core");
813 MODULE_LICENSE("GPL v2");