1 // SPDX-License-Identifier: GPL-2.0
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.
9 #define pr_fmt(fmt) "OF: overlay: " fmt
11 #include <linux/kernel.h>
12 #include <linux/module.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"
27 * struct target - info about current target node as recursing through overlay
28 * @np: node where current level of overlay will be applied
29 * @in_livetree: @np is a node in the live devicetree
31 * Used in the algorithm to create the portion of a changeset that describes
32 * an overlay fragment, which is a devicetree subtree. Initially @np is a node
33 * in the live devicetree where the overlay subtree is targeted to be grafted
34 * into. When recursing to the next level of the overlay subtree, the target
35 * also recurses to the next level of the live devicetree, as long as overlay
36 * subtree node also exists in the live devicetree. When a node in the overlay
37 * subtree does not exist at the same level in the live devicetree, target->np
38 * points to a newly allocated node, and all subsequent targets in the subtree
39 * will be newly allocated nodes.
42 struct device_node *np;
47 * struct fragment - info about fragment nodes in overlay expanded device tree
48 * @target: target of the overlay operation
49 * @overlay: pointer to the __overlay__ node
52 struct device_node *overlay;
53 struct device_node *target;
57 * struct overlay_changeset
58 * @id: changeset identifier
59 * @ovcs_list: list on which we are located
60 * @fdt: base of memory allocated to hold aligned FDT that was unflattened to create @overlay_tree
61 * @overlay_tree: expanded device tree that contains the fragment nodes
62 * @count: count of fragment structures
63 * @fragments: fragment nodes in the overlay expanded device tree
64 * @symbols_fragment: last element of @fragments[] is the __symbols__ node
65 * @cset: changeset to apply fragments to live device tree
67 struct overlay_changeset {
69 struct list_head ovcs_list;
71 struct device_node *overlay_tree;
73 struct fragment *fragments;
74 bool symbols_fragment;
75 struct of_changeset cset;
78 /* flags are sticky - once set, do not reset */
79 static int devicetree_state_flags;
80 #define DTSF_APPLY_FAIL 0x01
81 #define DTSF_REVERT_FAIL 0x02
84 * If a changeset apply or revert encounters an error, an attempt will
85 * be made to undo partial changes, but may fail. If the undo fails
86 * we do not know the state of the devicetree.
88 static int devicetree_corrupt(void)
90 return devicetree_state_flags &
91 (DTSF_APPLY_FAIL | DTSF_REVERT_FAIL);
94 static int build_changeset_next_level(struct overlay_changeset *ovcs,
95 struct target *target, const struct device_node *overlay_node);
98 * of_resolve_phandles() finds the largest phandle in the live tree.
99 * of_overlay_apply() may add a larger phandle to the live tree.
100 * Do not allow race between two overlays being applied simultaneously:
101 * mutex_lock(&of_overlay_phandle_mutex)
102 * of_resolve_phandles()
104 * mutex_unlock(&of_overlay_phandle_mutex)
106 static DEFINE_MUTEX(of_overlay_phandle_mutex);
108 void of_overlay_mutex_lock(void)
110 mutex_lock(&of_overlay_phandle_mutex);
113 void of_overlay_mutex_unlock(void)
115 mutex_unlock(&of_overlay_phandle_mutex);
119 static LIST_HEAD(ovcs_list);
120 static DEFINE_IDR(ovcs_idr);
122 static BLOCKING_NOTIFIER_HEAD(overlay_notify_chain);
125 * of_overlay_notifier_register() - Register notifier for overlay operations
126 * @nb: Notifier block to register
128 * Register for notification on overlay operations on device tree nodes. The
129 * reported actions definied by @of_reconfig_change. The notifier callback
130 * furthermore receives a pointer to the affected device tree node.
132 * Note that a notifier callback is not supposed to store pointers to a device
133 * tree node or its content beyond @OF_OVERLAY_POST_REMOVE corresponding to the
134 * respective node it received.
136 int of_overlay_notifier_register(struct notifier_block *nb)
138 return blocking_notifier_chain_register(&overlay_notify_chain, nb);
140 EXPORT_SYMBOL_GPL(of_overlay_notifier_register);
143 * of_overlay_notifier_unregister() - Unregister notifier for overlay operations
144 * @nb: Notifier block to unregister
146 int of_overlay_notifier_unregister(struct notifier_block *nb)
148 return blocking_notifier_chain_unregister(&overlay_notify_chain, nb);
150 EXPORT_SYMBOL_GPL(of_overlay_notifier_unregister);
152 static char *of_overlay_action_name[] = {
159 static int overlay_notify(struct overlay_changeset *ovcs,
160 enum of_overlay_notify_action action)
162 struct of_overlay_notify_data nd;
165 for (i = 0; i < ovcs->count; i++) {
166 struct fragment *fragment = &ovcs->fragments[i];
168 nd.target = fragment->target;
169 nd.overlay = fragment->overlay;
171 ret = blocking_notifier_call_chain(&overlay_notify_chain,
173 if (notifier_to_errno(ret)) {
174 ret = notifier_to_errno(ret);
175 pr_err("overlay changeset %s notifier error %d, target: %pOF\n",
176 of_overlay_action_name[action], ret, nd.target);
185 * The values of properties in the "/__symbols__" node are paths in
186 * the ovcs->overlay_tree. When duplicating the properties, the paths
187 * need to be adjusted to be the correct path for the live device tree.
189 * The paths refer to a node in the subtree of a fragment node's "__overlay__"
190 * node, for example "/fragment@0/__overlay__/symbol_path_tail",
191 * where symbol_path_tail can be a single node or it may be a multi-node path.
193 * The duplicated property value will be modified by replacing the
194 * "/fragment_name/__overlay/" portion of the value with the target
195 * path from the fragment node.
197 static struct property *dup_and_fixup_symbol_prop(
198 struct overlay_changeset *ovcs, const struct property *prop)
200 struct fragment *fragment;
201 struct property *new_prop;
202 struct device_node *fragment_node;
203 struct device_node *overlay_node;
205 const char *path_tail;
206 const char *target_path;
208 int overlay_name_len;
215 if (strnlen(prop->value, prop->length) >= prop->length)
218 path_len = strlen(path);
222 fragment_node = __of_find_node_by_path(ovcs->overlay_tree, path + 1);
223 overlay_node = __of_find_node_by_path(fragment_node, "__overlay__/");
224 of_node_put(fragment_node);
225 of_node_put(overlay_node);
227 for (k = 0; k < ovcs->count; k++) {
228 fragment = &ovcs->fragments[k];
229 if (fragment->overlay == overlay_node)
232 if (k >= ovcs->count)
235 overlay_name_len = snprintf(NULL, 0, "%pOF", fragment->overlay);
237 if (overlay_name_len > path_len)
239 path_tail = path + overlay_name_len;
240 path_tail_len = strlen(path_tail);
242 target_path = kasprintf(GFP_KERNEL, "%pOF", fragment->target);
245 target_path_len = strlen(target_path);
247 new_prop = kzalloc(sizeof(*new_prop), GFP_KERNEL);
249 goto err_free_target_path;
251 new_prop->name = kstrdup(prop->name, GFP_KERNEL);
252 new_prop->length = target_path_len + path_tail_len + 1;
253 new_prop->value = kzalloc(new_prop->length, GFP_KERNEL);
254 if (!new_prop->name || !new_prop->value)
255 goto err_free_new_prop;
257 strcpy(new_prop->value, target_path);
258 strcpy(new_prop->value + target_path_len, path_tail);
260 of_property_set_flag(new_prop, OF_DYNAMIC);
267 kfree(new_prop->name);
268 kfree(new_prop->value);
270 err_free_target_path:
277 * add_changeset_property() - add @overlay_prop to overlay changeset
278 * @ovcs: overlay changeset
279 * @target: where @overlay_prop will be placed
280 * @overlay_prop: property to add or update, from overlay tree
281 * @is_symbols_prop: 1 if @overlay_prop is from node "/__symbols__"
283 * If @overlay_prop does not already exist in live devicetree, add changeset
284 * entry to add @overlay_prop in @target, else add changeset entry to update
285 * value of @overlay_prop.
287 * @target may be either in the live devicetree or in a new subtree that
288 * is contained in the changeset.
290 * Some special properties are not added or updated (no error returned):
291 * "name", "phandle", "linux,phandle".
293 * Properties "#address-cells" and "#size-cells" are not updated if they
294 * are already in the live tree, but if present in the live tree, the values
295 * in the overlay must match the values in the live tree.
297 * Update of property in symbols node is not allowed.
299 * Return: 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
302 static int add_changeset_property(struct overlay_changeset *ovcs,
303 struct target *target, struct property *overlay_prop,
304 bool is_symbols_prop)
306 struct property *new_prop = NULL, *prop;
309 if (target->in_livetree)
310 if (!of_prop_cmp(overlay_prop->name, "name") ||
311 !of_prop_cmp(overlay_prop->name, "phandle") ||
312 !of_prop_cmp(overlay_prop->name, "linux,phandle"))
315 if (target->in_livetree)
316 prop = of_find_property(target->np, overlay_prop->name, NULL);
321 if (!of_prop_cmp(prop->name, "#address-cells")) {
322 if (!of_prop_val_eq(prop, overlay_prop)) {
323 pr_err("ERROR: changing value of #address-cells is not allowed in %pOF\n",
329 } else if (!of_prop_cmp(prop->name, "#size-cells")) {
330 if (!of_prop_val_eq(prop, overlay_prop)) {
331 pr_err("ERROR: changing value of #size-cells is not allowed in %pOF\n",
339 if (is_symbols_prop) {
342 new_prop = dup_and_fixup_symbol_prop(ovcs, overlay_prop);
344 new_prop = __of_prop_dup(overlay_prop, GFP_KERNEL);
351 if (!target->in_livetree) {
352 new_prop->next = target->np->deadprops;
353 target->np->deadprops = new_prop;
355 ret = of_changeset_add_property(&ovcs->cset, target->np,
358 ret = of_changeset_update_property(&ovcs->cset, target->np,
362 if (!of_node_check_flag(target->np, OF_OVERLAY))
363 pr_err("WARNING: memory leak will occur if overlay removed, property: %pOF/%s\n",
364 target->np, new_prop->name);
367 kfree(new_prop->name);
368 kfree(new_prop->value);
375 * add_changeset_node() - add @node (and children) to overlay changeset
376 * @ovcs: overlay changeset
377 * @target: where @node will be placed in live tree or changeset
378 * @node: node from within overlay device tree fragment
380 * If @node does not already exist in @target, add changeset entry
381 * to add @node in @target.
383 * If @node already exists in @target, and the existing node has
384 * a phandle, the overlay node is not allowed to have a phandle.
386 * If @node has child nodes, add the children recursively via
387 * build_changeset_next_level().
389 * NOTE_1: A live devicetree created from a flattened device tree (FDT) will
390 * not contain the full path in node->full_name. Thus an overlay
391 * created from an FDT also will not contain the full path in
392 * node->full_name. However, a live devicetree created from Open
393 * Firmware may have the full path in node->full_name.
395 * add_changeset_node() follows the FDT convention and does not include
396 * the full path in node->full_name. Even though it expects the overlay
397 * to not contain the full path, it uses kbasename() to remove the
398 * full path should it exist. It also uses kbasename() in comparisons
399 * to nodes in the live devicetree so that it can apply an overlay to
400 * a live devicetree created from Open Firmware.
402 * NOTE_2: Multiple mods of created nodes not supported.
404 * Return: 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
407 static int add_changeset_node(struct overlay_changeset *ovcs,
408 struct target *target, struct device_node *node)
410 const char *node_kbasename;
411 const __be32 *phandle;
412 struct device_node *tchild;
413 struct target target_child;
416 node_kbasename = kbasename(node->full_name);
418 for_each_child_of_node(target->np, tchild)
419 if (!of_node_cmp(node_kbasename, kbasename(tchild->full_name)))
423 tchild = __of_node_dup(NULL, node_kbasename);
427 tchild->parent = target->np;
428 tchild->name = __of_get_property(node, "name", NULL);
431 tchild->name = "<NULL>";
433 /* ignore obsolete "linux,phandle" */
434 phandle = __of_get_property(node, "phandle", &size);
435 if (phandle && (size == 4))
436 tchild->phandle = be32_to_cpup(phandle);
438 of_node_set_flag(tchild, OF_OVERLAY);
440 ret = of_changeset_attach_node(&ovcs->cset, tchild);
444 target_child.np = tchild;
445 target_child.in_livetree = false;
447 ret = build_changeset_next_level(ovcs, &target_child, node);
452 if (node->phandle && tchild->phandle) {
455 target_child.np = tchild;
456 target_child.in_livetree = target->in_livetree;
457 ret = build_changeset_next_level(ovcs, &target_child, node);
465 * build_changeset_next_level() - add level of overlay changeset
466 * @ovcs: overlay changeset
467 * @target: where to place @overlay_node in live tree
468 * @overlay_node: node from within an overlay device tree fragment
470 * Add the properties (if any) and nodes (if any) from @overlay_node to the
471 * @ovcs->cset changeset. If an added node has child nodes, they will
472 * be added recursively.
474 * Do not allow symbols node to have any children.
476 * Return: 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
477 * invalid @overlay_node.
479 static int build_changeset_next_level(struct overlay_changeset *ovcs,
480 struct target *target, const struct device_node *overlay_node)
482 struct device_node *child;
483 struct property *prop;
486 for_each_property_of_node(overlay_node, prop) {
487 ret = add_changeset_property(ovcs, target, prop, 0);
489 pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
490 target->np, prop->name, ret);
495 for_each_child_of_node(overlay_node, child) {
496 ret = add_changeset_node(ovcs, target, child);
498 pr_debug("Failed to apply node @%pOF/%pOFn, err=%d\n",
499 target->np, child, ret);
509 * Add the properties from __overlay__ node to the @ovcs->cset changeset.
511 static int build_changeset_symbols_node(struct overlay_changeset *ovcs,
512 struct target *target,
513 const struct device_node *overlay_symbols_node)
515 struct property *prop;
518 for_each_property_of_node(overlay_symbols_node, prop) {
519 ret = add_changeset_property(ovcs, target, prop, 1);
521 pr_debug("Failed to apply symbols prop @%pOF/%s, err=%d\n",
522 target->np, prop->name, ret);
530 static int find_dup_cset_node_entry(struct overlay_changeset *ovcs,
531 struct of_changeset_entry *ce_1)
533 struct of_changeset_entry *ce_2;
537 if (ce_1->action != OF_RECONFIG_ATTACH_NODE &&
538 ce_1->action != OF_RECONFIG_DETACH_NODE)
542 list_for_each_entry_continue(ce_2, &ovcs->cset.entries, node) {
543 if ((ce_2->action != OF_RECONFIG_ATTACH_NODE &&
544 ce_2->action != OF_RECONFIG_DETACH_NODE) ||
545 of_node_cmp(ce_1->np->full_name, ce_2->np->full_name))
548 fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
549 fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
550 node_path_match = !strcmp(fn_1, fn_2);
553 if (node_path_match) {
554 pr_err("ERROR: multiple fragments add and/or delete node %pOF\n",
563 static int find_dup_cset_prop(struct overlay_changeset *ovcs,
564 struct of_changeset_entry *ce_1)
566 struct of_changeset_entry *ce_2;
570 if (ce_1->action != OF_RECONFIG_ADD_PROPERTY &&
571 ce_1->action != OF_RECONFIG_REMOVE_PROPERTY &&
572 ce_1->action != OF_RECONFIG_UPDATE_PROPERTY)
576 list_for_each_entry_continue(ce_2, &ovcs->cset.entries, node) {
577 if ((ce_2->action != OF_RECONFIG_ADD_PROPERTY &&
578 ce_2->action != OF_RECONFIG_REMOVE_PROPERTY &&
579 ce_2->action != OF_RECONFIG_UPDATE_PROPERTY) ||
580 of_node_cmp(ce_1->np->full_name, ce_2->np->full_name))
583 fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
584 fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
585 node_path_match = !strcmp(fn_1, fn_2);
588 if (node_path_match &&
589 !of_prop_cmp(ce_1->prop->name, ce_2->prop->name)) {
590 pr_err("ERROR: multiple fragments add, update, and/or delete property %pOF/%s\n",
591 ce_1->np, ce_1->prop->name);
600 * changeset_dup_entry_check() - check for duplicate entries
601 * @ovcs: Overlay changeset
603 * Check changeset @ovcs->cset for multiple {add or delete} node entries for
604 * the same node or duplicate {add, delete, or update} properties entries
605 * for the same property.
607 * Return: 0 on success, or -EINVAL if duplicate changeset entry found.
609 static int changeset_dup_entry_check(struct overlay_changeset *ovcs)
611 struct of_changeset_entry *ce_1;
614 list_for_each_entry(ce_1, &ovcs->cset.entries, node) {
615 dup_entry |= find_dup_cset_node_entry(ovcs, ce_1);
616 dup_entry |= find_dup_cset_prop(ovcs, ce_1);
619 return dup_entry ? -EINVAL : 0;
623 * build_changeset() - populate overlay changeset in @ovcs from @ovcs->fragments
624 * @ovcs: Overlay changeset
626 * Create changeset @ovcs->cset to contain the nodes and properties of the
627 * overlay device tree fragments in @ovcs->fragments[]. If an error occurs,
628 * any portions of the changeset that were successfully created will remain
631 * Return: 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
632 * invalid overlay in @ovcs->fragments[].
634 static int build_changeset(struct overlay_changeset *ovcs)
636 struct fragment *fragment;
637 struct target target;
638 int fragments_count, i, ret;
641 * if there is a symbols fragment in ovcs->fragments[i] it is
642 * the final element in the array
644 if (ovcs->symbols_fragment)
645 fragments_count = ovcs->count - 1;
647 fragments_count = ovcs->count;
649 for (i = 0; i < fragments_count; i++) {
650 fragment = &ovcs->fragments[i];
652 target.np = fragment->target;
653 target.in_livetree = true;
654 ret = build_changeset_next_level(ovcs, &target,
657 pr_debug("fragment apply failed '%pOF'\n",
663 if (ovcs->symbols_fragment) {
664 fragment = &ovcs->fragments[ovcs->count - 1];
666 target.np = fragment->target;
667 target.in_livetree = true;
668 ret = build_changeset_symbols_node(ovcs, &target,
671 pr_debug("symbols fragment apply failed '%pOF'\n",
677 return changeset_dup_entry_check(ovcs);
681 * Find the target node using a number of different strategies
682 * in order of preference:
684 * 1) "target" property containing the phandle of the target
685 * 2) "target-path" property containing the path of the target
687 static struct device_node *find_target(struct device_node *info_node)
689 struct device_node *node;
694 ret = of_property_read_u32(info_node, "target", &val);
696 node = of_find_node_by_phandle(val);
698 pr_err("find target, node: %pOF, phandle 0x%x not found\n",
703 ret = of_property_read_string(info_node, "target-path", &path);
705 node = of_find_node_by_path(path);
707 pr_err("find target, node: %pOF, path '%s' not found\n",
712 pr_err("find target, node: %pOF, no target property\n", info_node);
718 * init_overlay_changeset() - initialize overlay changeset from overlay tree
719 * @ovcs: Overlay changeset to build
720 * @fdt: base of memory allocated to hold aligned FDT that was unflattened to create @tree
721 * @tree: Contains the overlay fragments and overlay fixup nodes
723 * Initialize @ovcs. Populate @ovcs->fragments with node information from
724 * the top level of @tree. The relevant top level nodes are the fragment
725 * nodes and the __symbols__ node. Any other top level node will be ignored.
727 * Return: 0 on success, -ENOMEM if memory allocation failure, -EINVAL if error
728 * detected in @tree, or -ENOSPC if idr_alloc() error.
730 static int init_overlay_changeset(struct overlay_changeset *ovcs,
731 const void *fdt, struct device_node *tree)
733 struct device_node *node, *overlay_node;
734 struct fragment *fragment;
735 struct fragment *fragments;
739 * Warn for some issues. Can not return -EINVAL for these until
740 * of_unittest_apply_overlay() is fixed to pass these checks.
742 if (!of_node_check_flag(tree, OF_DYNAMIC))
743 pr_debug("%s() tree is not dynamic\n", __func__);
745 if (!of_node_check_flag(tree, OF_DETACHED))
746 pr_debug("%s() tree is not detached\n", __func__);
748 if (!of_node_is_root(tree))
749 pr_debug("%s() tree is not root\n", __func__);
751 ovcs->overlay_tree = tree;
754 INIT_LIST_HEAD(&ovcs->ovcs_list);
756 of_changeset_init(&ovcs->cset);
758 id = idr_alloc(&ovcs_idr, ovcs, 1, 0, GFP_KERNEL);
765 for_each_child_of_node(tree, node) {
766 overlay_node = of_get_child_by_name(node, "__overlay__");
769 of_node_put(overlay_node);
773 node = of_get_child_by_name(tree, "__symbols__");
779 fragments = kcalloc(cnt, sizeof(*fragments), GFP_KERNEL);
786 for_each_child_of_node(tree, node) {
787 overlay_node = of_get_child_by_name(node, "__overlay__");
791 fragment = &fragments[cnt];
792 fragment->overlay = overlay_node;
793 fragment->target = find_target(node);
794 if (!fragment->target) {
795 of_node_put(fragment->overlay);
798 goto err_free_fragments;
805 * if there is a symbols fragment in ovcs->fragments[i] it is
806 * the final element in the array
808 node = of_get_child_by_name(tree, "__symbols__");
810 ovcs->symbols_fragment = 1;
811 fragment = &fragments[cnt];
812 fragment->overlay = node;
813 fragment->target = of_find_node_by_path("/__symbols__");
815 if (!fragment->target) {
816 pr_err("symbols in overlay, but not in live tree\n");
818 goto err_free_fragments;
825 pr_err("no fragments or symbols in overlay\n");
827 goto err_free_fragments;
832 ovcs->fragments = fragments;
839 idr_remove(&ovcs_idr, id);
841 pr_err("%s() failed, ret = %d\n", __func__, ret);
846 static void free_overlay_changeset(struct overlay_changeset *ovcs)
850 if (ovcs->cset.entries.next)
851 of_changeset_destroy(&ovcs->cset);
854 idr_remove(&ovcs_idr, ovcs->id);
856 for (i = 0; i < ovcs->count; i++) {
857 of_node_put(ovcs->fragments[i].target);
858 of_node_put(ovcs->fragments[i].overlay);
860 kfree(ovcs->fragments);
862 * There should be no live pointers into ovcs->overlay_tree and
863 * ovcs->fdt due to the policy that overlay notifiers are not allowed
864 * to retain pointers into the overlay devicetree.
866 kfree(ovcs->overlay_tree);
872 * internal documentation
874 * of_overlay_apply() - Create and apply an overlay changeset
875 * @fdt: base of memory allocated to hold the aligned FDT
876 * @tree: Expanded overlay device tree
877 * @ovcs_id: Pointer to overlay changeset id
879 * Creates and applies an overlay changeset.
881 * If an error occurs in a pre-apply notifier, then no changes are made
882 * to the device tree.
885 * A non-zero return value will not have created the changeset if error is from:
887 * - building the changeset
888 * - overlay changeset pre-apply notifier
890 * If an error is returned by an overlay changeset pre-apply notifier
891 * then no further overlay changeset pre-apply notifier will be called.
893 * A non-zero return value will have created the changeset if error is from:
894 * - overlay changeset entry notifier
895 * - overlay changeset post-apply notifier
897 * If an error is returned by an overlay changeset post-apply notifier
898 * then no further overlay changeset post-apply notifier will be called.
900 * If more than one notifier returns an error, then the last notifier
901 * error to occur is returned.
903 * If an error occurred while applying the overlay changeset, then an
904 * attempt is made to revert any changes that were made to the
905 * device tree. If there were any errors during the revert attempt
906 * then the state of the device tree can not be determined, and any
907 * following attempt to apply or remove an overlay changeset will be
910 * Returns 0 on success, or a negative error number. Overlay changeset
911 * id is returned to *ovcs_id.
914 static int of_overlay_apply(const void *fdt, struct device_node *tree,
917 struct overlay_changeset *ovcs;
918 int ret = 0, ret_revert, ret_tmp;
921 * As of this point, fdt and tree belong to the overlay changeset.
922 * overlay changeset code is responsible for freeing them.
925 if (devicetree_corrupt()) {
926 pr_err("devicetree state suspect, refuse to apply overlay\n");
933 ovcs = kzalloc(sizeof(*ovcs), GFP_KERNEL);
941 of_overlay_mutex_lock();
942 mutex_lock(&of_mutex);
944 ret = of_resolve_phandles(tree);
948 ret = init_overlay_changeset(ovcs, fdt, tree);
953 * after overlay_notify(), ovcs->overlay_tree related pointers may have
954 * leaked to drivers, so can not kfree() tree, aka ovcs->overlay_tree;
955 * and can not free memory containing aligned fdt. The aligned fdt
956 * is contained within the memory at ovcs->fdt, possibly at an offset
959 ret = overlay_notify(ovcs, OF_OVERLAY_PRE_APPLY);
961 pr_err("overlay changeset pre-apply notify error %d\n", ret);
962 goto err_free_overlay_changeset;
965 ret = build_changeset(ovcs);
967 goto err_free_overlay_changeset;
970 ret = __of_changeset_apply_entries(&ovcs->cset, &ret_revert);
973 pr_debug("overlay changeset revert error %d\n",
975 devicetree_state_flags |= DTSF_APPLY_FAIL;
977 goto err_free_overlay_changeset;
980 ret = __of_changeset_apply_notify(&ovcs->cset);
982 pr_err("overlay apply changeset entry notify error %d\n", ret);
983 /* notify failure is not fatal, continue */
985 list_add_tail(&ovcs->ovcs_list, &ovcs_list);
988 ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_APPLY);
990 pr_err("overlay changeset post-apply notify error %d\n",
1002 err_free_overlay_changeset:
1003 free_overlay_changeset(ovcs);
1006 mutex_unlock(&of_mutex);
1007 of_overlay_mutex_unlock();
1010 pr_debug("%s() err=%d\n", __func__, ret);
1015 int of_overlay_fdt_apply(const void *overlay_fdt, u32 overlay_fdt_size,
1019 void *new_fdt_align;
1022 struct device_node *overlay_root = NULL;
1026 if (overlay_fdt_size < sizeof(struct fdt_header) ||
1027 fdt_check_header(overlay_fdt)) {
1028 pr_err("Invalid overlay_fdt header\n");
1032 size = fdt_totalsize(overlay_fdt);
1033 if (overlay_fdt_size < size)
1037 * Must create permanent copy of FDT because of_fdt_unflatten_tree()
1038 * will create pointers to the passed in FDT in the unflattened tree.
1040 new_fdt = kmalloc(size + FDT_ALIGN_SIZE, GFP_KERNEL);
1044 new_fdt_align = PTR_ALIGN(new_fdt, FDT_ALIGN_SIZE);
1045 memcpy(new_fdt_align, overlay_fdt, size);
1047 of_fdt_unflatten_tree(new_fdt_align, NULL, &overlay_root);
1048 if (!overlay_root) {
1049 pr_err("unable to unflatten overlay_fdt\n");
1051 goto out_free_new_fdt;
1054 ret = of_overlay_apply(new_fdt, overlay_root, ovcs_id);
1057 * new_fdt and overlay_root now belong to the overlay
1059 * overlay changeset code is responsible for freeing them.
1073 EXPORT_SYMBOL_GPL(of_overlay_fdt_apply);
1076 * Find @np in @tree.
1078 * Returns 1 if @np is @tree or is contained in @tree, else 0
1080 static int find_node(struct device_node *tree, struct device_node *np)
1082 struct device_node *child;
1087 for_each_child_of_node(tree, child) {
1088 if (find_node(child, np)) {
1098 * Is @remove_ce_node a child of, a parent of, or the same as any
1099 * node in an overlay changeset more topmost than @remove_ovcs?
1101 * Returns 1 if found, else 0
1103 static int node_overlaps_later_cs(struct overlay_changeset *remove_ovcs,
1104 struct device_node *remove_ce_node)
1106 struct overlay_changeset *ovcs;
1107 struct of_changeset_entry *ce;
1109 list_for_each_entry_reverse(ovcs, &ovcs_list, ovcs_list) {
1110 if (ovcs == remove_ovcs)
1113 list_for_each_entry(ce, &ovcs->cset.entries, node) {
1114 if (find_node(ce->np, remove_ce_node)) {
1115 pr_err("%s: #%d overlaps with #%d @%pOF\n",
1116 __func__, remove_ovcs->id, ovcs->id,
1120 if (find_node(remove_ce_node, ce->np)) {
1121 pr_err("%s: #%d overlaps with #%d @%pOF\n",
1122 __func__, remove_ovcs->id, ovcs->id,
1133 * We can safely remove the overlay only if it's the top-most one.
1134 * Newly applied overlays are inserted at the tail of the overlay list,
1135 * so a top most overlay is the one that is closest to the tail.
1137 * The topmost check is done by exploiting this property. For each
1138 * affected device node in the log list we check if this overlay is
1139 * the one closest to the tail. If another overlay has affected this
1140 * device node and is closest to the tail, then removal is not permited.
1142 static int overlay_removal_is_ok(struct overlay_changeset *remove_ovcs)
1144 struct of_changeset_entry *remove_ce;
1146 list_for_each_entry(remove_ce, &remove_ovcs->cset.entries, node) {
1147 if (node_overlaps_later_cs(remove_ovcs, remove_ce->np)) {
1148 pr_err("overlay #%d is not topmost\n", remove_ovcs->id);
1157 * of_overlay_remove() - Revert and free an overlay changeset
1158 * @ovcs_id: Pointer to overlay changeset id
1160 * Removes an overlay if it is permissible. @ovcs_id was previously returned
1161 * by of_overlay_fdt_apply().
1163 * If an error occurred while attempting to revert the overlay changeset,
1164 * then an attempt is made to re-apply any changeset entry that was
1165 * reverted. If an error occurs on re-apply then the state of the device
1166 * tree can not be determined, and any following attempt to apply or remove
1167 * an overlay changeset will be refused.
1169 * A non-zero return value will not revert the changeset if error is from:
1170 * - parameter checks
1171 * - overlay changeset pre-remove notifier
1172 * - overlay changeset entry revert
1174 * If an error is returned by an overlay changeset pre-remove notifier
1175 * then no further overlay changeset pre-remove notifier will be called.
1177 * If more than one notifier returns an error, then the last notifier
1178 * error to occur is returned.
1180 * A non-zero return value will revert the changeset if error is from:
1181 * - overlay changeset entry notifier
1182 * - overlay changeset post-remove notifier
1184 * If an error is returned by an overlay changeset post-remove notifier
1185 * then no further overlay changeset post-remove notifier will be called.
1187 * Return: 0 on success, or a negative error number. *@ovcs_id is set to
1188 * zero after reverting the changeset, even if a subsequent error occurs.
1190 int of_overlay_remove(int *ovcs_id)
1192 struct overlay_changeset *ovcs;
1193 int ret, ret_apply, ret_tmp;
1195 if (devicetree_corrupt()) {
1196 pr_err("suspect devicetree state, refuse to remove overlay\n");
1201 mutex_lock(&of_mutex);
1203 ovcs = idr_find(&ovcs_idr, *ovcs_id);
1206 pr_err("remove: Could not find overlay #%d\n", *ovcs_id);
1210 if (!overlay_removal_is_ok(ovcs)) {
1215 ret = overlay_notify(ovcs, OF_OVERLAY_PRE_REMOVE);
1217 pr_err("overlay changeset pre-remove notify error %d\n", ret);
1221 list_del(&ovcs->ovcs_list);
1224 ret = __of_changeset_revert_entries(&ovcs->cset, &ret_apply);
1227 devicetree_state_flags |= DTSF_REVERT_FAIL;
1231 ret = __of_changeset_revert_notify(&ovcs->cset);
1233 pr_err("overlay remove changeset entry notify error %d\n", ret);
1234 /* notify failure is not fatal, continue */
1238 ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_REMOVE);
1240 pr_err("overlay changeset post-remove notify error %d\n",
1246 free_overlay_changeset(ovcs);
1249 mutex_unlock(&of_mutex);
1252 pr_debug("%s() err=%d\n", __func__, ret);
1256 EXPORT_SYMBOL_GPL(of_overlay_remove);
1259 * of_overlay_remove_all() - Reverts and frees all overlay changesets
1261 * Removes all overlays from the system in the correct order.
1263 * Return: 0 on success, or a negative error number
1265 int of_overlay_remove_all(void)
1267 struct overlay_changeset *ovcs, *ovcs_n;
1270 /* the tail of list is guaranteed to be safe to remove */
1271 list_for_each_entry_safe_reverse(ovcs, ovcs_n, &ovcs_list, ovcs_list) {
1272 ret = of_overlay_remove(&ovcs->id);
1279 EXPORT_SYMBOL_GPL(of_overlay_remove_all);