1 // SPDX-License-Identifier: GPL-2.0
3 * Functions for dealing with DT resolution
5 * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
6 * Copyright (C) 2012 Texas Instruments Inc.
9 #define pr_fmt(fmt) "OF: resolver: " fmt
11 #include <linux/kernel.h>
12 #include <linux/module.h>
14 #include <linux/of_device.h>
15 #include <linux/string.h>
16 #include <linux/ctype.h>
17 #include <linux/errno.h>
18 #include <linux/slab.h>
20 #include "of_private.h"
22 /* illegal phandle value (set when unresolved) */
23 #define OF_PHANDLE_ILLEGAL 0xdeadbeef
25 static phandle live_tree_max_phandle(void)
27 struct device_node *node;
31 raw_spin_lock_irqsave(&devtree_lock, flags);
33 for_each_of_allnodes(node) {
34 if (node->phandle != OF_PHANDLE_ILLEGAL &&
35 node->phandle > phandle)
36 phandle = node->phandle;
38 raw_spin_unlock_irqrestore(&devtree_lock, flags);
43 static void adjust_overlay_phandles(struct device_node *overlay,
46 struct device_node *child;
47 struct property *prop;
50 /* adjust node's phandle in node */
51 if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL)
52 overlay->phandle += phandle_delta;
54 /* copy adjusted phandle into *phandle properties */
55 for_each_property_of_node(overlay, prop) {
57 if (of_prop_cmp(prop->name, "phandle") &&
58 of_prop_cmp(prop->name, "linux,phandle"))
64 phandle = be32_to_cpup(prop->value);
65 if (phandle == OF_PHANDLE_ILLEGAL)
68 *(__be32 *)prop->value = cpu_to_be32(overlay->phandle);
71 for_each_child_of_node(overlay, child)
72 adjust_overlay_phandles(child, phandle_delta);
75 static int update_usages_of_a_phandle_reference(struct device_node *overlay,
76 struct property *prop_fixup, phandle phandle)
78 struct device_node *refnode;
79 struct property *prop;
80 char *value, *cur, *end, *node_path, *prop_name, *s;
84 value = kmemdup(prop_fixup->value, prop_fixup->length, GFP_KERNEL);
88 /* prop_fixup contains a list of tuples of path:property_name:offset */
89 end = value + prop_fixup->length;
90 for (cur = value; cur < end; cur += len + 1) {
109 err = kstrtoint(s, 10, &offset);
113 refnode = __of_find_node_by_full_path(of_node_get(overlay), node_path);
117 for_each_property_of_node(refnode, prop) {
118 if (!of_prop_cmp(prop->name, prop_name))
121 of_node_put(refnode);
128 *(__be32 *)(prop->value + offset) = cpu_to_be32(phandle);
136 /* compare nodes taking into account that 'name' strips out the @ part */
137 static int node_name_cmp(const struct device_node *dn1,
138 const struct device_node *dn2)
140 const char *n1 = kbasename(dn1->full_name);
141 const char *n2 = kbasename(dn2->full_name);
143 return of_node_cmp(n1, n2);
147 * Adjust the local phandle references by the given phandle delta.
149 * Subtree @local_fixups, which is overlay node __local_fixups__,
150 * mirrors the fragment node structure at the root of the overlay.
152 * For each property in the fragments that contains a phandle reference,
153 * @local_fixups has a property of the same name that contains a list
154 * of offsets of the phandle reference(s) within the respective property
155 * value(s). The values at these offsets will be fixed up.
157 static int adjust_local_phandle_references(struct device_node *local_fixups,
158 struct device_node *overlay, int phandle_delta)
160 struct device_node *child, *overlay_child;
161 struct property *prop_fix, *prop;
168 for_each_property_of_node(local_fixups, prop_fix) {
170 /* skip properties added automatically */
171 if (!of_prop_cmp(prop_fix->name, "name") ||
172 !of_prop_cmp(prop_fix->name, "phandle") ||
173 !of_prop_cmp(prop_fix->name, "linux,phandle"))
176 if ((prop_fix->length % 4) != 0 || prop_fix->length == 0)
178 count = prop_fix->length / sizeof(__be32);
180 for_each_property_of_node(overlay, prop) {
181 if (!of_prop_cmp(prop->name, prop_fix->name))
188 for (i = 0; i < count; i++) {
189 off = be32_to_cpu(((__be32 *)prop_fix->value)[i]);
190 if ((off + 4) > prop->length)
193 be32_add_cpu(prop->value + off, phandle_delta);
198 * These nested loops recurse down two subtrees in parallel, where the
199 * node names in the two subtrees match.
201 * The roots of the subtrees are the overlay's __local_fixups__ node
202 * and the overlay's root node.
204 for_each_child_of_node(local_fixups, child) {
206 for_each_child_of_node(overlay, overlay_child)
207 if (!node_name_cmp(child, overlay_child))
213 err = adjust_local_phandle_references(child, overlay_child,
223 * of_resolve_phandles - Relocate and resolve overlay against live tree
225 * @overlay: Pointer to devicetree overlay to relocate and resolve
227 * Modify (relocate) values of local phandles in @overlay to a range that
228 * does not conflict with the live expanded devicetree. Update references
229 * to the local phandles in @overlay. Update (resolve) phandle references
230 * in @overlay that refer to the live expanded devicetree.
232 * Phandle values in the live tree are in the range of
233 * 1 .. live_tree_max_phandle(). The range of phandle values in the overlay
234 * also begin with at 1. Adjust the phandle values in the overlay to begin
235 * at live_tree_max_phandle() + 1. Update references to the phandles to
236 * the adjusted phandle values.
238 * The name of each property in the "__fixups__" node in the overlay matches
239 * the name of a symbol (a label) in the live tree. The values of each
240 * property in the "__fixups__" node is a list of the property values in the
241 * overlay that need to be updated to contain the phandle reference
242 * corresponding to that symbol in the live tree. Update the references in
243 * the overlay with the phandle values in the live tree.
245 * @overlay must be detached.
247 * Resolving and applying @overlay to the live expanded devicetree must be
248 * protected by a mechanism to ensure that multiple overlays are processed
249 * in a single threaded manner so that multiple overlays will not relocate
250 * phandles to overlapping ranges. The mechanism to enforce this is not
253 * Return: %0 on success or a negative error value on error.
255 int of_resolve_phandles(struct device_node *overlay)
257 struct device_node *child, *local_fixups, *refnode;
258 struct device_node *tree_symbols, *overlay_fixups;
259 struct property *prop;
261 phandle phandle, phandle_delta;
267 pr_err("null overlay\n");
273 Temporarily disable check so that old style overlay unittests
274 do not fail when of_resolve_phandles() is moved into
277 if (!of_node_check_flag(overlay, OF_DETACHED)) {
278 pr_err("overlay not detached\n");
284 phandle_delta = live_tree_max_phandle() + 1;
285 adjust_overlay_phandles(overlay, phandle_delta);
287 for_each_child_of_node(overlay, local_fixups)
288 if (!of_node_cmp(local_fixups->name, "__local_fixups__"))
291 err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta);
295 overlay_fixups = NULL;
297 for_each_child_of_node(overlay, child) {
298 if (!of_node_cmp(child->name, "__fixups__"))
299 overlay_fixups = child;
302 if (!overlay_fixups) {
307 tree_symbols = of_find_node_by_path("/__symbols__");
309 pr_err("no symbols in root of device tree.\n");
314 for_each_property_of_node(overlay_fixups, prop) {
316 /* skip properties added automatically */
317 if (!of_prop_cmp(prop->name, "name"))
320 err = of_property_read_string(tree_symbols,
321 prop->name, &refpath);
325 refnode = of_find_node_by_path(refpath);
331 phandle = refnode->phandle;
332 of_node_put(refnode);
334 err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
341 pr_err("overlay phandle fixup failed: %d\n", err);
342 of_node_put(tree_symbols);
346 EXPORT_SYMBOL_GPL(of_resolve_phandles);