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 static phandle live_tree_max_phandle(void)
24 struct device_node *node;
28 raw_spin_lock_irqsave(&devtree_lock, flags);
30 for_each_of_allnodes(node) {
31 if (node->phandle != OF_PHANDLE_ILLEGAL &&
32 node->phandle > phandle)
33 phandle = node->phandle;
35 raw_spin_unlock_irqrestore(&devtree_lock, flags);
40 static void adjust_overlay_phandles(struct device_node *overlay,
43 struct device_node *child;
44 struct property *prop;
47 /* adjust node's phandle in node */
48 if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL)
49 overlay->phandle += phandle_delta;
51 /* copy adjusted phandle into *phandle properties */
52 for_each_property_of_node(overlay, prop) {
54 if (of_prop_cmp(prop->name, "phandle") &&
55 of_prop_cmp(prop->name, "linux,phandle"))
61 phandle = be32_to_cpup(prop->value);
62 if (phandle == OF_PHANDLE_ILLEGAL)
65 *(__be32 *)prop->value = cpu_to_be32(overlay->phandle);
68 for_each_child_of_node(overlay, child)
69 adjust_overlay_phandles(child, phandle_delta);
72 static int update_usages_of_a_phandle_reference(struct device_node *overlay,
73 struct property *prop_fixup, phandle phandle)
75 struct device_node *refnode;
76 struct property *prop;
77 char *value, *cur, *end, *node_path, *prop_name, *s;
81 value = kmemdup(prop_fixup->value, prop_fixup->length, GFP_KERNEL);
85 /* prop_fixup contains a list of tuples of path:property_name:offset */
86 end = value + prop_fixup->length;
87 for (cur = value; cur < end; cur += len + 1) {
106 err = kstrtoint(s, 10, &offset);
110 refnode = __of_find_node_by_full_path(of_node_get(overlay), node_path);
114 for_each_property_of_node(refnode, prop) {
115 if (!of_prop_cmp(prop->name, prop_name))
118 of_node_put(refnode);
125 *(__be32 *)(prop->value + offset) = cpu_to_be32(phandle);
133 /* compare nodes taking into account that 'name' strips out the @ part */
134 static int node_name_cmp(const struct device_node *dn1,
135 const struct device_node *dn2)
137 const char *n1 = kbasename(dn1->full_name);
138 const char *n2 = kbasename(dn2->full_name);
140 return of_node_cmp(n1, n2);
144 * Adjust the local phandle references by the given phandle delta.
146 * Subtree @local_fixups, which is overlay node __local_fixups__,
147 * mirrors the fragment node structure at the root of the overlay.
149 * For each property in the fragments that contains a phandle reference,
150 * @local_fixups has a property of the same name that contains a list
151 * of offsets of the phandle reference(s) within the respective property
152 * value(s). The values at these offsets will be fixed up.
154 static int adjust_local_phandle_references(struct device_node *local_fixups,
155 struct device_node *overlay, int phandle_delta)
157 struct device_node *child, *overlay_child;
158 struct property *prop_fix, *prop;
165 for_each_property_of_node(local_fixups, prop_fix) {
167 /* skip properties added automatically */
168 if (!of_prop_cmp(prop_fix->name, "name") ||
169 !of_prop_cmp(prop_fix->name, "phandle") ||
170 !of_prop_cmp(prop_fix->name, "linux,phandle"))
173 if ((prop_fix->length % 4) != 0 || prop_fix->length == 0)
175 count = prop_fix->length / sizeof(__be32);
177 for_each_property_of_node(overlay, prop) {
178 if (!of_prop_cmp(prop->name, prop_fix->name))
185 for (i = 0; i < count; i++) {
186 off = be32_to_cpu(((__be32 *)prop_fix->value)[i]);
187 if ((off + 4) > prop->length)
190 be32_add_cpu(prop->value + off, phandle_delta);
195 * These nested loops recurse down two subtrees in parallel, where the
196 * node names in the two subtrees match.
198 * The roots of the subtrees are the overlay's __local_fixups__ node
199 * and the overlay's root node.
201 for_each_child_of_node(local_fixups, child) {
203 for_each_child_of_node(overlay, overlay_child)
204 if (!node_name_cmp(child, overlay_child))
210 err = adjust_local_phandle_references(child, overlay_child,
220 * of_resolve_phandles - Relocate and resolve overlay against live tree
222 * @overlay: Pointer to devicetree overlay to relocate and resolve
224 * Modify (relocate) values of local phandles in @overlay to a range that
225 * does not conflict with the live expanded devicetree. Update references
226 * to the local phandles in @overlay. Update (resolve) phandle references
227 * in @overlay that refer to the live expanded devicetree.
229 * Phandle values in the live tree are in the range of
230 * 1 .. live_tree_max_phandle(). The range of phandle values in the overlay
231 * also begin with at 1. Adjust the phandle values in the overlay to begin
232 * at live_tree_max_phandle() + 1. Update references to the phandles to
233 * the adjusted phandle values.
235 * The name of each property in the "__fixups__" node in the overlay matches
236 * the name of a symbol (a label) in the live tree. The values of each
237 * property in the "__fixups__" node is a list of the property values in the
238 * overlay that need to be updated to contain the phandle reference
239 * corresponding to that symbol in the live tree. Update the references in
240 * the overlay with the phandle values in the live tree.
242 * @overlay must be detached.
244 * Resolving and applying @overlay to the live expanded devicetree must be
245 * protected by a mechanism to ensure that multiple overlays are processed
246 * in a single threaded manner so that multiple overlays will not relocate
247 * phandles to overlapping ranges. The mechanism to enforce this is not
250 * Return: %0 on success or a negative error value on error.
252 int of_resolve_phandles(struct device_node *overlay)
254 struct device_node *child, *local_fixups, *refnode;
255 struct device_node *tree_symbols, *overlay_fixups;
256 struct property *prop;
258 phandle phandle, phandle_delta;
264 pr_err("null overlay\n");
269 if (!of_node_check_flag(overlay, OF_DETACHED)) {
270 pr_err("overlay not detached\n");
275 phandle_delta = live_tree_max_phandle() + 1;
276 adjust_overlay_phandles(overlay, phandle_delta);
278 for_each_child_of_node(overlay, local_fixups)
279 if (!of_node_cmp(local_fixups->name, "__local_fixups__"))
282 err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta);
286 overlay_fixups = NULL;
288 for_each_child_of_node(overlay, child) {
289 if (!of_node_cmp(child->name, "__fixups__"))
290 overlay_fixups = child;
293 if (!overlay_fixups) {
298 tree_symbols = of_find_node_by_path("/__symbols__");
300 pr_err("no symbols in root of device tree.\n");
305 for_each_property_of_node(overlay_fixups, prop) {
307 /* skip properties added automatically */
308 if (!of_prop_cmp(prop->name, "name"))
311 err = of_property_read_string(tree_symbols,
312 prop->name, &refpath);
316 refnode = of_find_node_by_path(refpath);
322 phandle = refnode->phandle;
323 of_node_put(refnode);
325 err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
332 pr_err("overlay phandle fixup failed: %d\n", err);
333 of_node_put(tree_symbols);
337 EXPORT_SYMBOL_GPL(of_resolve_phandles);