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 * @overlay: pointer to the __overlay__ node
49 * @target: target of the overlay operation
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 * @new_fdt: Memory allocated to hold unflattened aligned FDT
61 * @overlay_mem: the memory chunk that contains @overlay_root
62 * @overlay_root: expanded device tree that contains the fragment nodes
63 * @notify_state: most recent notify action used on overlay
64 * @count: count of fragment structures
65 * @fragments: fragment nodes in the overlay expanded device tree
66 * @symbols_fragment: last element of @fragments[] is the __symbols__ node
67 * @cset: changeset to apply fragments to live device tree
69 struct overlay_changeset {
71 struct list_head ovcs_list;
73 const void *overlay_mem;
74 struct device_node *overlay_root;
75 enum of_overlay_notify_action notify_state;
77 struct fragment *fragments;
78 bool symbols_fragment;
79 struct of_changeset cset;
82 /* flags are sticky - once set, do not reset */
83 static int devicetree_state_flags;
84 #define DTSF_APPLY_FAIL 0x01
85 #define DTSF_REVERT_FAIL 0x02
88 * If a changeset apply or revert encounters an error, an attempt will
89 * be made to undo partial changes, but may fail. If the undo fails
90 * we do not know the state of the devicetree.
92 static int devicetree_corrupt(void)
94 return devicetree_state_flags &
95 (DTSF_APPLY_FAIL | DTSF_REVERT_FAIL);
98 static int build_changeset_next_level(struct overlay_changeset *ovcs,
99 struct target *target, const struct device_node *overlay_node);
102 * of_resolve_phandles() finds the largest phandle in the live tree.
103 * of_overlay_apply() may add a larger phandle to the live tree.
104 * Do not allow race between two overlays being applied simultaneously:
105 * mutex_lock(&of_overlay_phandle_mutex)
106 * of_resolve_phandles()
108 * mutex_unlock(&of_overlay_phandle_mutex)
110 static DEFINE_MUTEX(of_overlay_phandle_mutex);
112 void of_overlay_mutex_lock(void)
114 mutex_lock(&of_overlay_phandle_mutex);
117 void of_overlay_mutex_unlock(void)
119 mutex_unlock(&of_overlay_phandle_mutex);
122 static LIST_HEAD(ovcs_list);
123 static DEFINE_IDR(ovcs_idr);
125 static BLOCKING_NOTIFIER_HEAD(overlay_notify_chain);
128 * of_overlay_notifier_register() - Register notifier for overlay operations
129 * @nb: Notifier block to register
131 * Register for notification on overlay operations on device tree nodes. The
132 * reported actions definied by @of_reconfig_change. The notifier callback
133 * furthermore receives a pointer to the affected device tree node.
135 * Note that a notifier callback is not supposed to store pointers to a device
136 * tree node or its content beyond @OF_OVERLAY_POST_REMOVE corresponding to the
137 * respective node it received.
139 int of_overlay_notifier_register(struct notifier_block *nb)
141 return blocking_notifier_chain_register(&overlay_notify_chain, nb);
143 EXPORT_SYMBOL_GPL(of_overlay_notifier_register);
146 * of_overlay_notifier_unregister() - Unregister notifier for overlay operations
147 * @nb: Notifier block to unregister
149 int of_overlay_notifier_unregister(struct notifier_block *nb)
151 return blocking_notifier_chain_unregister(&overlay_notify_chain, nb);
153 EXPORT_SYMBOL_GPL(of_overlay_notifier_unregister);
155 static int overlay_notify(struct overlay_changeset *ovcs,
156 enum of_overlay_notify_action action)
158 struct of_overlay_notify_data nd;
161 ovcs->notify_state = action;
163 for (i = 0; i < ovcs->count; i++) {
164 struct fragment *fragment = &ovcs->fragments[i];
166 nd.target = fragment->target;
167 nd.overlay = fragment->overlay;
169 ret = blocking_notifier_call_chain(&overlay_notify_chain,
171 if (notifier_to_errno(ret)) {
172 ret = notifier_to_errno(ret);
173 pr_err("overlay changeset %s notifier error %d, target: %pOF\n",
174 of_overlay_action_name(action), ret, nd.target);
183 * The values of properties in the "/__symbols__" node are paths in
184 * the ovcs->overlay_root. When duplicating the properties, the paths
185 * need to be adjusted to be the correct path for the live device tree.
187 * The paths refer to a node in the subtree of a fragment node's "__overlay__"
188 * node, for example "/fragment@0/__overlay__/symbol_path_tail",
189 * where symbol_path_tail can be a single node or it may be a multi-node path.
191 * The duplicated property value will be modified by replacing the
192 * "/fragment_name/__overlay/" portion of the value with the target
193 * path from the fragment node.
195 static struct property *dup_and_fixup_symbol_prop(
196 struct overlay_changeset *ovcs, const struct property *prop)
198 struct fragment *fragment;
199 struct property *new_prop;
200 struct device_node *fragment_node;
201 struct device_node *overlay_node;
203 const char *path_tail;
204 const char *target_path;
206 int overlay_name_len;
213 if (strnlen(prop->value, prop->length) >= prop->length)
216 path_len = strlen(path);
220 fragment_node = __of_find_node_by_path(ovcs->overlay_root, path + 1);
221 overlay_node = __of_find_node_by_path(fragment_node, "__overlay__/");
222 of_node_put(fragment_node);
223 of_node_put(overlay_node);
225 for (k = 0; k < ovcs->count; k++) {
226 fragment = &ovcs->fragments[k];
227 if (fragment->overlay == overlay_node)
230 if (k >= ovcs->count)
233 overlay_name_len = snprintf(NULL, 0, "%pOF", fragment->overlay);
235 if (overlay_name_len > path_len)
237 path_tail = path + overlay_name_len;
238 path_tail_len = strlen(path_tail);
240 target_path = kasprintf(GFP_KERNEL, "%pOF", fragment->target);
243 target_path_len = strlen(target_path);
244 if (!strcmp(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 = !fn_1 || !fn_2 || !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 = !fn_1 || !fn_2 || !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,
688 struct device_node *target_base)
690 struct device_node *node;
696 ret = of_property_read_u32(info_node, "target", &val);
698 node = of_find_node_by_phandle(val);
700 pr_err("find target, node: %pOF, phandle 0x%x not found\n",
705 ret = of_property_read_string(info_node, "target-path", &path);
708 target_path = kasprintf(GFP_KERNEL, "%pOF%s", target_base, path);
711 node = of_find_node_by_path(target_path);
713 pr_err("find target, node: %pOF, path '%s' not found\n",
714 info_node, target_path);
718 node = of_find_node_by_path(path);
720 pr_err("find target, node: %pOF, path '%s' not found\n",
727 pr_err("find target, node: %pOF, no target property\n", info_node);
733 * init_overlay_changeset() - initialize overlay changeset from overlay tree
734 * @ovcs: Overlay changeset to build
735 * @target_base: Point to the target node to apply overlay
737 * Initialize @ovcs. Populate @ovcs->fragments with node information from
738 * the top level of @overlay_root. The relevant top level nodes are the
739 * fragment nodes and the __symbols__ node. Any other top level node will
740 * be ignored. Populate other @ovcs fields.
742 * Return: 0 on success, -ENOMEM if memory allocation failure, -EINVAL if error
743 * detected in @overlay_root. On error return, the caller of
744 * init_overlay_changeset() must call free_overlay_changeset().
746 static int init_overlay_changeset(struct overlay_changeset *ovcs,
747 struct device_node *target_base)
749 struct device_node *node, *overlay_node;
750 struct fragment *fragment;
751 struct fragment *fragments;
755 * None of the resources allocated by this function will be freed in
756 * the error paths. Instead the caller of this function is required
757 * to call free_overlay_changeset() (which will free the resources)
762 * Warn for some issues. Can not return -EINVAL for these until
763 * of_unittest_apply_overlay() is fixed to pass these checks.
765 if (!of_node_check_flag(ovcs->overlay_root, OF_DYNAMIC))
766 pr_debug("%s() ovcs->overlay_root is not dynamic\n", __func__);
768 if (!of_node_check_flag(ovcs->overlay_root, OF_DETACHED))
769 pr_debug("%s() ovcs->overlay_root is not detached\n", __func__);
771 if (!of_node_is_root(ovcs->overlay_root))
772 pr_debug("%s() ovcs->overlay_root is not root\n", __func__);
777 for_each_child_of_node(ovcs->overlay_root, node) {
778 overlay_node = of_get_child_by_name(node, "__overlay__");
781 of_node_put(overlay_node);
785 node = of_get_child_by_name(ovcs->overlay_root, "__symbols__");
791 fragments = kcalloc(cnt, sizeof(*fragments), GFP_KERNEL);
796 ovcs->fragments = fragments;
799 for_each_child_of_node(ovcs->overlay_root, node) {
800 overlay_node = of_get_child_by_name(node, "__overlay__");
804 fragment = &fragments[cnt];
805 fragment->overlay = overlay_node;
806 fragment->target = find_target(node, target_base);
807 if (!fragment->target) {
808 of_node_put(fragment->overlay);
818 * if there is a symbols fragment in ovcs->fragments[i] it is
819 * the final element in the array
821 node = of_get_child_by_name(ovcs->overlay_root, "__symbols__");
823 ovcs->symbols_fragment = 1;
824 fragment = &fragments[cnt];
825 fragment->overlay = node;
826 fragment->target = of_find_node_by_path("/__symbols__");
828 if (!fragment->target) {
829 pr_err("symbols in overlay, but not in live tree\n");
839 pr_err("no fragments or symbols in overlay\n");
849 pr_err("%s() failed, ret = %d\n", __func__, ret);
854 static void free_overlay_changeset(struct overlay_changeset *ovcs)
858 if (ovcs->cset.entries.next)
859 of_changeset_destroy(&ovcs->cset);
862 idr_remove(&ovcs_idr, ovcs->id);
863 list_del(&ovcs->ovcs_list);
868 for (i = 0; i < ovcs->count; i++) {
869 of_node_put(ovcs->fragments[i].target);
870 of_node_put(ovcs->fragments[i].overlay);
872 kfree(ovcs->fragments);
875 * There should be no live pointers into ovcs->overlay_mem and
876 * ovcs->new_fdt due to the policy that overlay notifiers are not
877 * allowed to retain pointers into the overlay devicetree other
878 * than during the window from OF_OVERLAY_PRE_APPLY overlay
879 * notifiers until the OF_OVERLAY_POST_REMOVE overlay notifiers.
881 * A memory leak will occur here if within the window.
884 if (ovcs->notify_state == OF_OVERLAY_INIT ||
885 ovcs->notify_state == OF_OVERLAY_POST_REMOVE) {
886 kfree(ovcs->overlay_mem);
887 kfree(ovcs->new_fdt);
893 * internal documentation
895 * of_overlay_apply() - Create and apply an overlay changeset
896 * @ovcs: overlay changeset
897 * @base: point to the target node to apply overlay
899 * Creates and applies an overlay changeset.
901 * If an error is returned by an overlay changeset pre-apply notifier
902 * then no further overlay changeset pre-apply notifier will be called.
904 * If an error is returned by an overlay changeset post-apply notifier
905 * then no further overlay changeset post-apply notifier will be called.
907 * If more than one notifier returns an error, then the last notifier
908 * error to occur is returned.
910 * If an error occurred while applying the overlay changeset, then an
911 * attempt is made to revert any changes that were made to the
912 * device tree. If there were any errors during the revert attempt
913 * then the state of the device tree can not be determined, and any
914 * following attempt to apply or remove an overlay changeset will be
917 * Returns 0 on success, or a negative error number. On error return,
918 * the caller of of_overlay_apply() must call free_overlay_changeset().
921 static int of_overlay_apply(struct overlay_changeset *ovcs,
922 struct device_node *base)
924 int ret = 0, ret_revert, ret_tmp;
926 ret = of_resolve_phandles(ovcs->overlay_root);
930 ret = init_overlay_changeset(ovcs, base);
934 ret = overlay_notify(ovcs, OF_OVERLAY_PRE_APPLY);
938 ret = build_changeset(ovcs);
943 ret = __of_changeset_apply_entries(&ovcs->cset, &ret_revert);
946 pr_debug("overlay changeset revert error %d\n",
948 devicetree_state_flags |= DTSF_APPLY_FAIL;
953 ret = __of_changeset_apply_notify(&ovcs->cset);
955 pr_err("overlay apply changeset entry notify error %d\n", ret);
956 /* notify failure is not fatal, continue */
958 ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_APPLY);
964 pr_debug("%s() err=%d\n", __func__, ret);
970 * of_overlay_fdt_apply() - Create and apply an overlay changeset
971 * @overlay_fdt: pointer to overlay FDT
972 * @overlay_fdt_size: number of bytes in @overlay_fdt
973 * @ret_ovcs_id: pointer for returning created changeset id
974 * @base: pointer for the target node to apply overlay
976 * Creates and applies an overlay changeset.
978 * See of_overlay_apply() for important behavior information.
980 * Return: 0 on success, or a negative error number. *@ret_ovcs_id is set to
981 * the value of overlay changeset id, which can be passed to of_overlay_remove()
982 * to remove the overlay.
984 * On error return, the changeset may be partially applied. This is especially
985 * likely if an OF_OVERLAY_POST_APPLY notifier returns an error. In this case
986 * the caller should call of_overlay_remove() with the value in *@ret_ovcs_id.
989 int of_overlay_fdt_apply(const void *overlay_fdt, u32 overlay_fdt_size,
990 int *ret_ovcs_id, struct device_node *base)
997 struct overlay_changeset *ovcs;
1001 if (devicetree_corrupt()) {
1002 pr_err("devicetree state suspect, refuse to apply overlay\n");
1006 if (overlay_fdt_size < sizeof(struct fdt_header) ||
1007 fdt_check_header(overlay_fdt)) {
1008 pr_err("Invalid overlay_fdt header\n");
1012 size = fdt_totalsize(overlay_fdt);
1013 if (overlay_fdt_size < size)
1016 ovcs = kzalloc(sizeof(*ovcs), GFP_KERNEL);
1020 of_overlay_mutex_lock();
1021 mutex_lock(&of_mutex);
1024 * ovcs->notify_state must be set to OF_OVERLAY_INIT before allocating
1025 * ovcs resources, implicitly set by kzalloc() of ovcs
1028 ovcs->id = idr_alloc(&ovcs_idr, ovcs, 1, 0, GFP_KERNEL);
1029 if (ovcs->id <= 0) {
1034 INIT_LIST_HEAD(&ovcs->ovcs_list);
1035 list_add_tail(&ovcs->ovcs_list, &ovcs_list);
1036 of_changeset_init(&ovcs->cset);
1039 * Must create permanent copy of FDT because of_fdt_unflatten_tree()
1040 * will create pointers to the passed in FDT in the unflattened tree.
1042 new_fdt = kmalloc(size + FDT_ALIGN_SIZE, GFP_KERNEL);
1047 ovcs->new_fdt = new_fdt;
1049 new_fdt_align = PTR_ALIGN(new_fdt, FDT_ALIGN_SIZE);
1050 memcpy(new_fdt_align, overlay_fdt, size);
1052 overlay_mem = of_fdt_unflatten_tree(new_fdt_align, NULL,
1053 &ovcs->overlay_root);
1055 pr_err("unable to unflatten overlay_fdt\n");
1059 ovcs->overlay_mem = overlay_mem;
1061 ret = of_overlay_apply(ovcs, base);
1063 * If of_overlay_apply() error, calling free_overlay_changeset() may
1064 * result in a memory leak if the apply partly succeeded, so do NOT
1065 * goto err_free_ovcs. Instead, the caller of of_overlay_fdt_apply()
1066 * can call of_overlay_remove();
1068 *ret_ovcs_id = ovcs->id;
1072 free_overlay_changeset(ovcs);
1075 mutex_unlock(&of_mutex);
1076 of_overlay_mutex_unlock();
1079 EXPORT_SYMBOL_GPL(of_overlay_fdt_apply);
1082 * Find @np in @tree.
1084 * Returns 1 if @np is @tree or is contained in @tree, else 0
1086 static int find_node(struct device_node *tree, struct device_node *np)
1088 struct device_node *child;
1093 for_each_child_of_node(tree, child) {
1094 if (find_node(child, np)) {
1104 * Is @remove_ce_node a child of, a parent of, or the same as any
1105 * node in an overlay changeset more topmost than @remove_ovcs?
1107 * Returns 1 if found, else 0
1109 static int node_overlaps_later_cs(struct overlay_changeset *remove_ovcs,
1110 struct device_node *remove_ce_node)
1112 struct overlay_changeset *ovcs;
1113 struct of_changeset_entry *ce;
1115 list_for_each_entry_reverse(ovcs, &ovcs_list, ovcs_list) {
1116 if (ovcs == remove_ovcs)
1119 list_for_each_entry(ce, &ovcs->cset.entries, node) {
1120 if (find_node(ce->np, remove_ce_node)) {
1121 pr_err("%s: #%d overlaps with #%d @%pOF\n",
1122 __func__, remove_ovcs->id, ovcs->id,
1126 if (find_node(remove_ce_node, ce->np)) {
1127 pr_err("%s: #%d overlaps with #%d @%pOF\n",
1128 __func__, remove_ovcs->id, ovcs->id,
1139 * We can safely remove the overlay only if it's the top-most one.
1140 * Newly applied overlays are inserted at the tail of the overlay list,
1141 * so a top most overlay is the one that is closest to the tail.
1143 * The topmost check is done by exploiting this property. For each
1144 * affected device node in the log list we check if this overlay is
1145 * the one closest to the tail. If another overlay has affected this
1146 * device node and is closest to the tail, then removal is not permitted.
1148 static int overlay_removal_is_ok(struct overlay_changeset *remove_ovcs)
1150 struct of_changeset_entry *remove_ce;
1152 list_for_each_entry(remove_ce, &remove_ovcs->cset.entries, node) {
1153 if (node_overlaps_later_cs(remove_ovcs, remove_ce->np)) {
1154 pr_err("overlay #%d is not topmost\n", remove_ovcs->id);
1163 * of_overlay_remove() - Revert and free an overlay changeset
1164 * @ovcs_id: Pointer to overlay changeset id
1166 * Removes an overlay if it is permissible. @ovcs_id was previously returned
1167 * by of_overlay_fdt_apply().
1169 * If an error occurred while attempting to revert the overlay changeset,
1170 * then an attempt is made to re-apply any changeset entry that was
1171 * reverted. If an error occurs on re-apply then the state of the device
1172 * tree can not be determined, and any following attempt to apply or remove
1173 * an overlay changeset will be refused.
1175 * A non-zero return value will not revert the changeset if error is from:
1176 * - parameter checks
1177 * - overlay changeset pre-remove notifier
1178 * - overlay changeset entry revert
1180 * If an error is returned by an overlay changeset pre-remove notifier
1181 * then no further overlay changeset pre-remove notifier will be called.
1183 * If more than one notifier returns an error, then the last notifier
1184 * error to occur is returned.
1186 * A non-zero return value will revert the changeset if error is from:
1187 * - overlay changeset entry notifier
1188 * - overlay changeset post-remove notifier
1190 * If an error is returned by an overlay changeset post-remove notifier
1191 * then no further overlay changeset post-remove notifier will be called.
1193 * Return: 0 on success, or a negative error number. *@ovcs_id is set to
1194 * zero after reverting the changeset, even if a subsequent error occurs.
1196 int of_overlay_remove(int *ovcs_id)
1198 struct overlay_changeset *ovcs;
1199 int ret, ret_apply, ret_tmp;
1201 if (devicetree_corrupt()) {
1202 pr_err("suspect devicetree state, refuse to remove overlay\n");
1207 mutex_lock(&of_mutex);
1209 ovcs = idr_find(&ovcs_idr, *ovcs_id);
1212 pr_err("remove: Could not find overlay #%d\n", *ovcs_id);
1216 if (!overlay_removal_is_ok(ovcs)) {
1221 ret = overlay_notify(ovcs, OF_OVERLAY_PRE_REMOVE);
1226 ret = __of_changeset_revert_entries(&ovcs->cset, &ret_apply);
1229 devicetree_state_flags |= DTSF_REVERT_FAIL;
1233 ret = __of_changeset_revert_notify(&ovcs->cset);
1235 pr_err("overlay remove changeset entry notify error %d\n", ret);
1236 /* notify failure is not fatal, continue */
1241 * Note that the overlay memory will be kfree()ed by
1242 * free_overlay_changeset() even if the notifier for
1243 * OF_OVERLAY_POST_REMOVE returns an error.
1245 ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_REMOVE);
1250 free_overlay_changeset(ovcs);
1254 * If jumped over free_overlay_changeset(), then did not kfree()
1255 * overlay related memory. This is a memory leak unless a subsequent
1256 * of_overlay_remove() of this overlay is successful.
1258 mutex_unlock(&of_mutex);
1261 pr_debug("%s() err=%d\n", __func__, ret);
1265 EXPORT_SYMBOL_GPL(of_overlay_remove);
1268 * of_overlay_remove_all() - Reverts and frees all overlay changesets
1270 * Removes all overlays from the system in the correct order.
1272 * Return: 0 on success, or a negative error number
1274 int of_overlay_remove_all(void)
1276 struct overlay_changeset *ovcs, *ovcs_n;
1279 /* the tail of list is guaranteed to be safe to remove */
1280 list_for_each_entry_safe_reverse(ovcs, ovcs_n, &ovcs_list, ovcs_list) {
1281 ret = of_overlay_remove(&ovcs->id);
1288 EXPORT_SYMBOL_GPL(of_overlay_remove_all);