Linux 4.18.10
[linux/fpc-iii.git] / drivers / of / overlay.c
blobeda57ef12fd057b3d92c750dec983703e85f38e3
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Functions for working with device tree overlays
5 * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
6 * Copyright (C) 2012 Texas Instruments Inc.
7 */
9 #define pr_fmt(fmt) "OF: overlay: " fmt
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/of.h>
14 #include <linux/of_device.h>
15 #include <linux/of_fdt.h>
16 #include <linux/string.h>
17 #include <linux/ctype.h>
18 #include <linux/errno.h>
19 #include <linux/slab.h>
20 #include <linux/libfdt.h>
21 #include <linux/err.h>
22 #include <linux/idr.h>
24 #include "of_private.h"
26 /**
27 * struct fragment - info about fragment nodes in overlay expanded device tree
28 * @target: target of the overlay operation
29 * @overlay: pointer to the __overlay__ node
31 struct fragment {
32 struct device_node *target;
33 struct device_node *overlay;
36 /**
37 * struct overlay_changeset
38 * @id: changeset identifier
39 * @ovcs_list: list on which we are located
40 * @fdt: FDT that was unflattened to create @overlay_tree
41 * @overlay_tree: expanded device tree that contains the fragment nodes
42 * @count: count of fragment structures
43 * @fragments: fragment nodes in the overlay expanded device tree
44 * @symbols_fragment: last element of @fragments[] is the __symbols__ node
45 * @cset: changeset to apply fragments to live device tree
47 struct overlay_changeset {
48 int id;
49 struct list_head ovcs_list;
50 const void *fdt;
51 struct device_node *overlay_tree;
52 int count;
53 struct fragment *fragments;
54 bool symbols_fragment;
55 struct of_changeset cset;
58 /* flags are sticky - once set, do not reset */
59 static int devicetree_state_flags;
60 #define DTSF_APPLY_FAIL 0x01
61 #define DTSF_REVERT_FAIL 0x02
64 * If a changeset apply or revert encounters an error, an attempt will
65 * be made to undo partial changes, but may fail. If the undo fails
66 * we do not know the state of the devicetree.
68 static int devicetree_corrupt(void)
70 return devicetree_state_flags &
71 (DTSF_APPLY_FAIL | DTSF_REVERT_FAIL);
74 static int build_changeset_next_level(struct overlay_changeset *ovcs,
75 struct device_node *target_node,
76 const struct device_node *overlay_node);
79 * of_resolve_phandles() finds the largest phandle in the live tree.
80 * of_overlay_apply() may add a larger phandle to the live tree.
81 * Do not allow race between two overlays being applied simultaneously:
82 * mutex_lock(&of_overlay_phandle_mutex)
83 * of_resolve_phandles()
84 * of_overlay_apply()
85 * mutex_unlock(&of_overlay_phandle_mutex)
87 static DEFINE_MUTEX(of_overlay_phandle_mutex);
89 void of_overlay_mutex_lock(void)
91 mutex_lock(&of_overlay_phandle_mutex);
94 void of_overlay_mutex_unlock(void)
96 mutex_unlock(&of_overlay_phandle_mutex);
100 static LIST_HEAD(ovcs_list);
101 static DEFINE_IDR(ovcs_idr);
103 static BLOCKING_NOTIFIER_HEAD(overlay_notify_chain);
106 * of_overlay_notifier_register() - Register notifier for overlay operations
107 * @nb: Notifier block to register
109 * Register for notification on overlay operations on device tree nodes. The
110 * reported actions definied by @of_reconfig_change. The notifier callback
111 * furthermore receives a pointer to the affected device tree node.
113 * Note that a notifier callback is not supposed to store pointers to a device
114 * tree node or its content beyond @OF_OVERLAY_POST_REMOVE corresponding to the
115 * respective node it received.
117 int of_overlay_notifier_register(struct notifier_block *nb)
119 return blocking_notifier_chain_register(&overlay_notify_chain, nb);
121 EXPORT_SYMBOL_GPL(of_overlay_notifier_register);
124 * of_overlay_notifier_register() - Unregister notifier for overlay operations
125 * @nb: Notifier block to unregister
127 int of_overlay_notifier_unregister(struct notifier_block *nb)
129 return blocking_notifier_chain_unregister(&overlay_notify_chain, nb);
131 EXPORT_SYMBOL_GPL(of_overlay_notifier_unregister);
133 static char *of_overlay_action_name[] = {
134 "pre-apply",
135 "post-apply",
136 "pre-remove",
137 "post-remove",
140 static int overlay_notify(struct overlay_changeset *ovcs,
141 enum of_overlay_notify_action action)
143 struct of_overlay_notify_data nd;
144 int i, ret;
146 for (i = 0; i < ovcs->count; i++) {
147 struct fragment *fragment = &ovcs->fragments[i];
149 nd.target = fragment->target;
150 nd.overlay = fragment->overlay;
152 ret = blocking_notifier_call_chain(&overlay_notify_chain,
153 action, &nd);
154 if (ret == NOTIFY_OK || ret == NOTIFY_STOP)
155 return 0;
156 if (ret) {
157 ret = notifier_to_errno(ret);
158 pr_err("overlay changeset %s notifier error %d, target: %pOF\n",
159 of_overlay_action_name[action], ret, nd.target);
160 return ret;
164 return 0;
168 * The values of properties in the "/__symbols__" node are paths in
169 * the ovcs->overlay_tree. When duplicating the properties, the paths
170 * need to be adjusted to be the correct path for the live device tree.
172 * The paths refer to a node in the subtree of a fragment node's "__overlay__"
173 * node, for example "/fragment@0/__overlay__/symbol_path_tail",
174 * where symbol_path_tail can be a single node or it may be a multi-node path.
176 * The duplicated property value will be modified by replacing the
177 * "/fragment_name/__overlay/" portion of the value with the target
178 * path from the fragment node.
180 static struct property *dup_and_fixup_symbol_prop(
181 struct overlay_changeset *ovcs, const struct property *prop)
183 struct fragment *fragment;
184 struct property *new_prop;
185 struct device_node *fragment_node;
186 struct device_node *overlay_node;
187 const char *path;
188 const char *path_tail;
189 const char *target_path;
190 int k;
191 int overlay_name_len;
192 int path_len;
193 int path_tail_len;
194 int target_path_len;
196 if (!prop->value)
197 return NULL;
198 if (strnlen(prop->value, prop->length) >= prop->length)
199 return NULL;
200 path = prop->value;
201 path_len = strlen(path);
203 if (path_len < 1)
204 return NULL;
205 fragment_node = __of_find_node_by_path(ovcs->overlay_tree, path + 1);
206 overlay_node = __of_find_node_by_path(fragment_node, "__overlay__/");
207 of_node_put(fragment_node);
208 of_node_put(overlay_node);
210 for (k = 0; k < ovcs->count; k++) {
211 fragment = &ovcs->fragments[k];
212 if (fragment->overlay == overlay_node)
213 break;
215 if (k >= ovcs->count)
216 return NULL;
218 overlay_name_len = snprintf(NULL, 0, "%pOF", fragment->overlay);
220 if (overlay_name_len > path_len)
221 return NULL;
222 path_tail = path + overlay_name_len;
223 path_tail_len = strlen(path_tail);
225 target_path = kasprintf(GFP_KERNEL, "%pOF", fragment->target);
226 if (!target_path)
227 return NULL;
228 target_path_len = strlen(target_path);
230 new_prop = kzalloc(sizeof(*new_prop), GFP_KERNEL);
231 if (!new_prop)
232 goto err_free_target_path;
234 new_prop->name = kstrdup(prop->name, GFP_KERNEL);
235 new_prop->length = target_path_len + path_tail_len + 1;
236 new_prop->value = kzalloc(new_prop->length, GFP_KERNEL);
237 if (!new_prop->name || !new_prop->value)
238 goto err_free_new_prop;
240 strcpy(new_prop->value, target_path);
241 strcpy(new_prop->value + target_path_len, path_tail);
243 of_property_set_flag(new_prop, OF_DYNAMIC);
245 return new_prop;
247 err_free_new_prop:
248 kfree(new_prop->name);
249 kfree(new_prop->value);
250 kfree(new_prop);
251 err_free_target_path:
252 kfree(target_path);
254 return NULL;
258 * add_changeset_property() - add @overlay_prop to overlay changeset
259 * @ovcs: overlay changeset
260 * @target_node: where to place @overlay_prop in live tree
261 * @overlay_prop: property to add or update, from overlay tree
262 * @is_symbols_prop: 1 if @overlay_prop is from node "/__symbols__"
264 * If @overlay_prop does not already exist in @target_node, add changeset entry
265 * to add @overlay_prop in @target_node, else add changeset entry to update
266 * value of @overlay_prop.
268 * Some special properties are not updated (no error returned).
270 * Update of property in symbols node is not allowed.
272 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
273 * invalid @overlay.
275 static int add_changeset_property(struct overlay_changeset *ovcs,
276 struct device_node *target_node,
277 struct property *overlay_prop,
278 bool is_symbols_prop)
280 struct property *new_prop = NULL, *prop;
281 int ret = 0;
283 prop = of_find_property(target_node, overlay_prop->name, NULL);
285 if (!of_prop_cmp(overlay_prop->name, "name") ||
286 !of_prop_cmp(overlay_prop->name, "phandle") ||
287 !of_prop_cmp(overlay_prop->name, "linux,phandle"))
288 return 0;
290 if (is_symbols_prop) {
291 if (prop)
292 return -EINVAL;
293 new_prop = dup_and_fixup_symbol_prop(ovcs, overlay_prop);
294 } else {
295 new_prop = __of_prop_dup(overlay_prop, GFP_KERNEL);
298 if (!new_prop)
299 return -ENOMEM;
301 if (!prop)
302 ret = of_changeset_add_property(&ovcs->cset, target_node,
303 new_prop);
304 else
305 ret = of_changeset_update_property(&ovcs->cset, target_node,
306 new_prop);
308 if (ret) {
309 kfree(new_prop->name);
310 kfree(new_prop->value);
311 kfree(new_prop);
313 return ret;
317 * add_changeset_node() - add @node (and children) to overlay changeset
318 * @ovcs: overlay changeset
319 * @target_node: where to place @node in live tree
320 * @node: node from within overlay device tree fragment
322 * If @node does not already exist in @target_node, add changeset entry
323 * to add @node in @target_node.
325 * If @node already exists in @target_node, and the existing node has
326 * a phandle, the overlay node is not allowed to have a phandle.
328 * If @node has child nodes, add the children recursively via
329 * build_changeset_next_level().
331 * NOTE_1: A live devicetree created from a flattened device tree (FDT) will
332 * not contain the full path in node->full_name. Thus an overlay
333 * created from an FDT also will not contain the full path in
334 * node->full_name. However, a live devicetree created from Open
335 * Firmware may have the full path in node->full_name.
337 * add_changeset_node() follows the FDT convention and does not include
338 * the full path in node->full_name. Even though it expects the overlay
339 * to not contain the full path, it uses kbasename() to remove the
340 * full path should it exist. It also uses kbasename() in comparisons
341 * to nodes in the live devicetree so that it can apply an overlay to
342 * a live devicetree created from Open Firmware.
344 * NOTE_2: Multiple mods of created nodes not supported.
345 * If more than one fragment contains a node that does not already exist
346 * in the live tree, then for each fragment of_changeset_attach_node()
347 * will add a changeset entry to add the node. When the changeset is
348 * applied, __of_attach_node() will attach the node twice (once for
349 * each fragment). At this point the device tree will be corrupted.
351 * TODO: add integrity check to ensure that multiple fragments do not
352 * create the same node.
354 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
355 * invalid @overlay.
357 static int add_changeset_node(struct overlay_changeset *ovcs,
358 struct device_node *target_node, struct device_node *node)
360 const char *node_kbasename;
361 struct device_node *tchild;
362 int ret = 0;
364 node_kbasename = kbasename(node->full_name);
366 for_each_child_of_node(target_node, tchild)
367 if (!of_node_cmp(node_kbasename, kbasename(tchild->full_name)))
368 break;
370 if (!tchild) {
371 tchild = __of_node_dup(node, node_kbasename);
372 if (!tchild)
373 return -ENOMEM;
375 tchild->parent = target_node;
377 ret = of_changeset_attach_node(&ovcs->cset, tchild);
378 if (ret)
379 return ret;
381 return build_changeset_next_level(ovcs, tchild, node);
384 if (node->phandle && tchild->phandle)
385 ret = -EINVAL;
386 else
387 ret = build_changeset_next_level(ovcs, tchild, node);
388 of_node_put(tchild);
390 return ret;
394 * build_changeset_next_level() - add level of overlay changeset
395 * @ovcs: overlay changeset
396 * @target_node: where to place @overlay_node in live tree
397 * @overlay_node: node from within an overlay device tree fragment
399 * Add the properties (if any) and nodes (if any) from @overlay_node to the
400 * @ovcs->cset changeset. If an added node has child nodes, they will
401 * be added recursively.
403 * Do not allow symbols node to have any children.
405 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
406 * invalid @overlay_node.
408 static int build_changeset_next_level(struct overlay_changeset *ovcs,
409 struct device_node *target_node,
410 const struct device_node *overlay_node)
412 struct device_node *child;
413 struct property *prop;
414 int ret;
416 for_each_property_of_node(overlay_node, prop) {
417 ret = add_changeset_property(ovcs, target_node, prop, 0);
418 if (ret) {
419 pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
420 target_node, prop->name, ret);
421 return ret;
425 for_each_child_of_node(overlay_node, child) {
426 ret = add_changeset_node(ovcs, target_node, child);
427 if (ret) {
428 pr_debug("Failed to apply node @%pOF/%s, err=%d\n",
429 target_node, child->name, ret);
430 of_node_put(child);
431 return ret;
435 return 0;
439 * Add the properties from __overlay__ node to the @ovcs->cset changeset.
441 static int build_changeset_symbols_node(struct overlay_changeset *ovcs,
442 struct device_node *target_node,
443 const struct device_node *overlay_symbols_node)
445 struct property *prop;
446 int ret;
448 for_each_property_of_node(overlay_symbols_node, prop) {
449 ret = add_changeset_property(ovcs, target_node, prop, 1);
450 if (ret) {
451 pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
452 target_node, prop->name, ret);
453 return ret;
457 return 0;
461 * build_changeset() - populate overlay changeset in @ovcs from @ovcs->fragments
462 * @ovcs: Overlay changeset
464 * Create changeset @ovcs->cset to contain the nodes and properties of the
465 * overlay device tree fragments in @ovcs->fragments[]. If an error occurs,
466 * any portions of the changeset that were successfully created will remain
467 * in @ovcs->cset.
469 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
470 * invalid overlay in @ovcs->fragments[].
472 static int build_changeset(struct overlay_changeset *ovcs)
474 struct fragment *fragment;
475 int fragments_count, i, ret;
478 * if there is a symbols fragment in ovcs->fragments[i] it is
479 * the final element in the array
481 if (ovcs->symbols_fragment)
482 fragments_count = ovcs->count - 1;
483 else
484 fragments_count = ovcs->count;
486 for (i = 0; i < fragments_count; i++) {
487 fragment = &ovcs->fragments[i];
489 ret = build_changeset_next_level(ovcs, fragment->target,
490 fragment->overlay);
491 if (ret) {
492 pr_debug("apply failed '%pOF'\n", fragment->target);
493 return ret;
497 if (ovcs->symbols_fragment) {
498 fragment = &ovcs->fragments[ovcs->count - 1];
499 ret = build_changeset_symbols_node(ovcs, fragment->target,
500 fragment->overlay);
501 if (ret) {
502 pr_debug("apply failed '%pOF'\n", fragment->target);
503 return ret;
507 return 0;
511 * Find the target node using a number of different strategies
512 * in order of preference:
514 * 1) "target" property containing the phandle of the target
515 * 2) "target-path" property containing the path of the target
517 static struct device_node *find_target_node(struct device_node *info_node)
519 struct device_node *node;
520 const char *path;
521 u32 val;
522 int ret;
524 ret = of_property_read_u32(info_node, "target", &val);
525 if (!ret) {
526 node = of_find_node_by_phandle(val);
527 if (!node)
528 pr_err("find target, node: %pOF, phandle 0x%x not found\n",
529 info_node, val);
530 return node;
533 ret = of_property_read_string(info_node, "target-path", &path);
534 if (!ret) {
535 node = of_find_node_by_path(path);
536 if (!node)
537 pr_err("find target, node: %pOF, path '%s' not found\n",
538 info_node, path);
539 return node;
542 pr_err("find target, node: %pOF, no target property\n", info_node);
544 return NULL;
548 * init_overlay_changeset() - initialize overlay changeset from overlay tree
549 * @ovcs: Overlay changeset to build
550 * @fdt: the FDT that was unflattened to create @tree
551 * @tree: Contains all the overlay fragments and overlay fixup nodes
553 * Initialize @ovcs. Populate @ovcs->fragments with node information from
554 * the top level of @tree. The relevant top level nodes are the fragment
555 * nodes and the __symbols__ node. Any other top level node will be ignored.
557 * Returns 0 on success, -ENOMEM if memory allocation failure, -EINVAL if error
558 * detected in @tree, or -ENOSPC if idr_alloc() error.
560 static int init_overlay_changeset(struct overlay_changeset *ovcs,
561 const void *fdt, struct device_node *tree)
563 struct device_node *node, *overlay_node;
564 struct fragment *fragment;
565 struct fragment *fragments;
566 int cnt, id, ret;
569 * Warn for some issues. Can not return -EINVAL for these until
570 * of_unittest_apply_overlay() is fixed to pass these checks.
572 if (!of_node_check_flag(tree, OF_DYNAMIC))
573 pr_debug("%s() tree is not dynamic\n", __func__);
575 if (!of_node_check_flag(tree, OF_DETACHED))
576 pr_debug("%s() tree is not detached\n", __func__);
578 if (!of_node_is_root(tree))
579 pr_debug("%s() tree is not root\n", __func__);
581 ovcs->overlay_tree = tree;
582 ovcs->fdt = fdt;
584 INIT_LIST_HEAD(&ovcs->ovcs_list);
586 of_changeset_init(&ovcs->cset);
588 id = idr_alloc(&ovcs_idr, ovcs, 1, 0, GFP_KERNEL);
589 if (id <= 0)
590 return id;
592 cnt = 0;
594 /* fragment nodes */
595 for_each_child_of_node(tree, node) {
596 overlay_node = of_get_child_by_name(node, "__overlay__");
597 if (overlay_node) {
598 cnt++;
599 of_node_put(overlay_node);
603 node = of_get_child_by_name(tree, "__symbols__");
604 if (node) {
605 cnt++;
606 of_node_put(node);
609 fragments = kcalloc(cnt, sizeof(*fragments), GFP_KERNEL);
610 if (!fragments) {
611 ret = -ENOMEM;
612 goto err_free_idr;
615 cnt = 0;
616 for_each_child_of_node(tree, node) {
617 overlay_node = of_get_child_by_name(node, "__overlay__");
618 if (!overlay_node)
619 continue;
621 fragment = &fragments[cnt];
622 fragment->overlay = overlay_node;
623 fragment->target = find_target_node(node);
624 if (!fragment->target) {
625 of_node_put(fragment->overlay);
626 ret = -EINVAL;
627 goto err_free_fragments;
630 cnt++;
634 * if there is a symbols fragment in ovcs->fragments[i] it is
635 * the final element in the array
637 node = of_get_child_by_name(tree, "__symbols__");
638 if (node) {
639 ovcs->symbols_fragment = 1;
640 fragment = &fragments[cnt];
641 fragment->overlay = node;
642 fragment->target = of_find_node_by_path("/__symbols__");
644 if (!fragment->target) {
645 pr_err("symbols in overlay, but not in live tree\n");
646 ret = -EINVAL;
647 goto err_free_fragments;
650 cnt++;
653 if (!cnt) {
654 pr_err("no fragments or symbols in overlay\n");
655 ret = -EINVAL;
656 goto err_free_fragments;
659 ovcs->id = id;
660 ovcs->count = cnt;
661 ovcs->fragments = fragments;
663 return 0;
665 err_free_fragments:
666 kfree(fragments);
667 err_free_idr:
668 idr_remove(&ovcs_idr, id);
670 pr_err("%s() failed, ret = %d\n", __func__, ret);
672 return ret;
675 static void free_overlay_changeset(struct overlay_changeset *ovcs)
677 int i;
679 if (ovcs->cset.entries.next)
680 of_changeset_destroy(&ovcs->cset);
682 if (ovcs->id)
683 idr_remove(&ovcs_idr, ovcs->id);
685 for (i = 0; i < ovcs->count; i++) {
686 of_node_put(ovcs->fragments[i].target);
687 of_node_put(ovcs->fragments[i].overlay);
689 kfree(ovcs->fragments);
691 * There should be no live pointers into ovcs->overlay_tree and
692 * ovcs->fdt due to the policy that overlay notifiers are not allowed
693 * to retain pointers into the overlay devicetree.
695 kfree(ovcs->overlay_tree);
696 kfree(ovcs->fdt);
697 kfree(ovcs);
701 * internal documentation
703 * of_overlay_apply() - Create and apply an overlay changeset
704 * @fdt: the FDT that was unflattened to create @tree
705 * @tree: Expanded overlay device tree
706 * @ovcs_id: Pointer to overlay changeset id
708 * Creates and applies an overlay changeset.
710 * If an error occurs in a pre-apply notifier, then no changes are made
711 * to the device tree.
714 * A non-zero return value will not have created the changeset if error is from:
715 * - parameter checks
716 * - building the changeset
717 * - overlay changeset pre-apply notifier
719 * If an error is returned by an overlay changeset pre-apply notifier
720 * then no further overlay changeset pre-apply notifier will be called.
722 * A non-zero return value will have created the changeset if error is from:
723 * - overlay changeset entry notifier
724 * - overlay changeset post-apply notifier
726 * If an error is returned by an overlay changeset post-apply notifier
727 * then no further overlay changeset post-apply notifier will be called.
729 * If more than one notifier returns an error, then the last notifier
730 * error to occur is returned.
732 * If an error occurred while applying the overlay changeset, then an
733 * attempt is made to revert any changes that were made to the
734 * device tree. If there were any errors during the revert attempt
735 * then the state of the device tree can not be determined, and any
736 * following attempt to apply or remove an overlay changeset will be
737 * refused.
739 * Returns 0 on success, or a negative error number. Overlay changeset
740 * id is returned to *ovcs_id.
743 static int of_overlay_apply(const void *fdt, struct device_node *tree,
744 int *ovcs_id)
746 struct overlay_changeset *ovcs;
747 int ret = 0, ret_revert, ret_tmp;
750 * As of this point, fdt and tree belong to the overlay changeset.
751 * overlay changeset code is responsible for freeing them.
754 if (devicetree_corrupt()) {
755 pr_err("devicetree state suspect, refuse to apply overlay\n");
756 kfree(fdt);
757 kfree(tree);
758 ret = -EBUSY;
759 goto out;
762 ovcs = kzalloc(sizeof(*ovcs), GFP_KERNEL);
763 if (!ovcs) {
764 kfree(fdt);
765 kfree(tree);
766 ret = -ENOMEM;
767 goto out;
770 of_overlay_mutex_lock();
771 mutex_lock(&of_mutex);
773 ret = of_resolve_phandles(tree);
774 if (ret)
775 goto err_free_tree;
777 ret = init_overlay_changeset(ovcs, fdt, tree);
778 if (ret)
779 goto err_free_tree;
782 * after overlay_notify(), ovcs->overlay_tree related pointers may have
783 * leaked to drivers, so can not kfree() tree, aka ovcs->overlay_tree;
784 * and can not free fdt, aka ovcs->fdt
786 ret = overlay_notify(ovcs, OF_OVERLAY_PRE_APPLY);
787 if (ret) {
788 pr_err("overlay changeset pre-apply notify error %d\n", ret);
789 goto err_free_overlay_changeset;
792 ret = build_changeset(ovcs);
793 if (ret)
794 goto err_free_overlay_changeset;
796 ret_revert = 0;
797 ret = __of_changeset_apply_entries(&ovcs->cset, &ret_revert);
798 if (ret) {
799 if (ret_revert) {
800 pr_debug("overlay changeset revert error %d\n",
801 ret_revert);
802 devicetree_state_flags |= DTSF_APPLY_FAIL;
804 goto err_free_overlay_changeset;
807 of_populate_phandle_cache();
809 ret = __of_changeset_apply_notify(&ovcs->cset);
810 if (ret)
811 pr_err("overlay changeset entry notify error %d\n", ret);
812 /* notify failure is not fatal, continue */
814 list_add_tail(&ovcs->ovcs_list, &ovcs_list);
815 *ovcs_id = ovcs->id;
817 ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_APPLY);
818 if (ret_tmp) {
819 pr_err("overlay changeset post-apply notify error %d\n",
820 ret_tmp);
821 if (!ret)
822 ret = ret_tmp;
825 goto out_unlock;
827 err_free_tree:
828 kfree(fdt);
829 kfree(tree);
831 err_free_overlay_changeset:
832 free_overlay_changeset(ovcs);
834 out_unlock:
835 mutex_unlock(&of_mutex);
836 of_overlay_mutex_unlock();
838 out:
839 pr_debug("%s() err=%d\n", __func__, ret);
841 return ret;
844 int of_overlay_fdt_apply(const void *overlay_fdt, u32 overlay_fdt_size,
845 int *ovcs_id)
847 const void *new_fdt;
848 int ret;
849 u32 size;
850 struct device_node *overlay_root;
852 *ovcs_id = 0;
853 ret = 0;
855 if (overlay_fdt_size < sizeof(struct fdt_header) ||
856 fdt_check_header(overlay_fdt)) {
857 pr_err("Invalid overlay_fdt header\n");
858 return -EINVAL;
861 size = fdt_totalsize(overlay_fdt);
862 if (overlay_fdt_size < size)
863 return -EINVAL;
866 * Must create permanent copy of FDT because of_fdt_unflatten_tree()
867 * will create pointers to the passed in FDT in the unflattened tree.
869 new_fdt = kmemdup(overlay_fdt, size, GFP_KERNEL);
870 if (!new_fdt)
871 return -ENOMEM;
873 of_fdt_unflatten_tree(new_fdt, NULL, &overlay_root);
874 if (!overlay_root) {
875 pr_err("unable to unflatten overlay_fdt\n");
876 ret = -EINVAL;
877 goto out_free_new_fdt;
880 ret = of_overlay_apply(new_fdt, overlay_root, ovcs_id);
881 if (ret < 0) {
883 * new_fdt and overlay_root now belong to the overlay
884 * changeset.
885 * overlay changeset code is responsible for freeing them.
887 goto out;
890 return 0;
893 out_free_new_fdt:
894 kfree(new_fdt);
896 out:
897 return ret;
899 EXPORT_SYMBOL_GPL(of_overlay_fdt_apply);
902 * Find @np in @tree.
904 * Returns 1 if @np is @tree or is contained in @tree, else 0
906 static int find_node(struct device_node *tree, struct device_node *np)
908 struct device_node *child;
910 if (tree == np)
911 return 1;
913 for_each_child_of_node(tree, child) {
914 if (find_node(child, np)) {
915 of_node_put(child);
916 return 1;
920 return 0;
924 * Is @remove_ce_node a child of, a parent of, or the same as any
925 * node in an overlay changeset more topmost than @remove_ovcs?
927 * Returns 1 if found, else 0
929 static int node_overlaps_later_cs(struct overlay_changeset *remove_ovcs,
930 struct device_node *remove_ce_node)
932 struct overlay_changeset *ovcs;
933 struct of_changeset_entry *ce;
935 list_for_each_entry_reverse(ovcs, &ovcs_list, ovcs_list) {
936 if (ovcs == remove_ovcs)
937 break;
939 list_for_each_entry(ce, &ovcs->cset.entries, node) {
940 if (find_node(ce->np, remove_ce_node)) {
941 pr_err("%s: #%d overlaps with #%d @%pOF\n",
942 __func__, remove_ovcs->id, ovcs->id,
943 remove_ce_node);
944 return 1;
946 if (find_node(remove_ce_node, ce->np)) {
947 pr_err("%s: #%d overlaps with #%d @%pOF\n",
948 __func__, remove_ovcs->id, ovcs->id,
949 remove_ce_node);
950 return 1;
955 return 0;
959 * We can safely remove the overlay only if it's the top-most one.
960 * Newly applied overlays are inserted at the tail of the overlay list,
961 * so a top most overlay is the one that is closest to the tail.
963 * The topmost check is done by exploiting this property. For each
964 * affected device node in the log list we check if this overlay is
965 * the one closest to the tail. If another overlay has affected this
966 * device node and is closest to the tail, then removal is not permited.
968 static int overlay_removal_is_ok(struct overlay_changeset *remove_ovcs)
970 struct of_changeset_entry *remove_ce;
972 list_for_each_entry(remove_ce, &remove_ovcs->cset.entries, node) {
973 if (node_overlaps_later_cs(remove_ovcs, remove_ce->np)) {
974 pr_err("overlay #%d is not topmost\n", remove_ovcs->id);
975 return 0;
979 return 1;
983 * of_overlay_remove() - Revert and free an overlay changeset
984 * @ovcs_id: Pointer to overlay changeset id
986 * Removes an overlay if it is permissible. @ovcs_id was previously returned
987 * by of_overlay_fdt_apply().
989 * If an error occurred while attempting to revert the overlay changeset,
990 * then an attempt is made to re-apply any changeset entry that was
991 * reverted. If an error occurs on re-apply then the state of the device
992 * tree can not be determined, and any following attempt to apply or remove
993 * an overlay changeset will be refused.
995 * A non-zero return value will not revert the changeset if error is from:
996 * - parameter checks
997 * - overlay changeset pre-remove notifier
998 * - overlay changeset entry revert
1000 * If an error is returned by an overlay changeset pre-remove notifier
1001 * then no further overlay changeset pre-remove notifier will be called.
1003 * If more than one notifier returns an error, then the last notifier
1004 * error to occur is returned.
1006 * A non-zero return value will revert the changeset if error is from:
1007 * - overlay changeset entry notifier
1008 * - overlay changeset post-remove notifier
1010 * If an error is returned by an overlay changeset post-remove notifier
1011 * then no further overlay changeset post-remove notifier will be called.
1013 * Returns 0 on success, or a negative error number. *ovcs_id is set to
1014 * zero after reverting the changeset, even if a subsequent error occurs.
1016 int of_overlay_remove(int *ovcs_id)
1018 struct overlay_changeset *ovcs;
1019 int ret, ret_apply, ret_tmp;
1021 ret = 0;
1023 if (devicetree_corrupt()) {
1024 pr_err("suspect devicetree state, refuse to remove overlay\n");
1025 ret = -EBUSY;
1026 goto out;
1029 mutex_lock(&of_mutex);
1031 ovcs = idr_find(&ovcs_idr, *ovcs_id);
1032 if (!ovcs) {
1033 ret = -ENODEV;
1034 pr_err("remove: Could not find overlay #%d\n", *ovcs_id);
1035 goto out_unlock;
1038 if (!overlay_removal_is_ok(ovcs)) {
1039 ret = -EBUSY;
1040 goto out_unlock;
1043 ret = overlay_notify(ovcs, OF_OVERLAY_PRE_REMOVE);
1044 if (ret) {
1045 pr_err("overlay changeset pre-remove notify error %d\n", ret);
1046 goto out_unlock;
1049 list_del(&ovcs->ovcs_list);
1052 * Disable phandle cache. Avoids race condition that would arise
1053 * from removing cache entry when the associated node is deleted.
1055 of_free_phandle_cache();
1057 ret_apply = 0;
1058 ret = __of_changeset_revert_entries(&ovcs->cset, &ret_apply);
1060 of_populate_phandle_cache();
1062 if (ret) {
1063 if (ret_apply)
1064 devicetree_state_flags |= DTSF_REVERT_FAIL;
1065 goto out_unlock;
1068 ret = __of_changeset_revert_notify(&ovcs->cset);
1069 if (ret)
1070 pr_err("overlay changeset entry notify error %d\n", ret);
1071 /* notify failure is not fatal, continue */
1073 *ovcs_id = 0;
1075 ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_REMOVE);
1076 if (ret_tmp) {
1077 pr_err("overlay changeset post-remove notify error %d\n",
1078 ret_tmp);
1079 if (!ret)
1080 ret = ret_tmp;
1083 free_overlay_changeset(ovcs);
1085 out_unlock:
1086 mutex_unlock(&of_mutex);
1088 out:
1089 pr_debug("%s() err=%d\n", __func__, ret);
1091 return ret;
1093 EXPORT_SYMBOL_GPL(of_overlay_remove);
1096 * of_overlay_remove_all() - Reverts and frees all overlay changesets
1098 * Removes all overlays from the system in the correct order.
1100 * Returns 0 on success, or a negative error number
1102 int of_overlay_remove_all(void)
1104 struct overlay_changeset *ovcs, *ovcs_n;
1105 int ret;
1107 /* the tail of list is guaranteed to be safe to remove */
1108 list_for_each_entry_safe_reverse(ovcs, ovcs_n, &ovcs_list, ovcs_list) {
1109 ret = of_overlay_remove(&ovcs->id);
1110 if (ret)
1111 return ret;
1114 return 0;
1116 EXPORT_SYMBOL_GPL(of_overlay_remove_all);