2 * Functions for dealing with DT resolution
4 * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
5 * Copyright (C) 2012 Texas Instruments Inc.
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * version 2 as published by the Free Software Foundation.
12 #define pr_fmt(fmt) "OF: resolver: " fmt
14 #include <linux/kernel.h>
15 #include <linux/module.h>
17 #include <linux/of_device.h>
18 #include <linux/string.h>
19 #include <linux/ctype.h>
20 #include <linux/errno.h>
21 #include <linux/slab.h>
23 #include "of_private.h"
25 /* illegal phandle value (set when unresolved) */
26 #define OF_PHANDLE_ILLEGAL 0xdeadbeef
28 static phandle live_tree_max_phandle(void)
30 struct device_node *node;
34 raw_spin_lock_irqsave(&devtree_lock, flags);
36 for_each_of_allnodes(node) {
37 if (node->phandle != OF_PHANDLE_ILLEGAL &&
38 node->phandle > phandle)
39 phandle = node->phandle;
41 raw_spin_unlock_irqrestore(&devtree_lock, flags);
46 static void adjust_overlay_phandles(struct device_node *overlay,
49 struct device_node *child;
50 struct property *prop;
53 /* adjust node's phandle in node */
54 if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL)
55 overlay->phandle += phandle_delta;
57 /* copy adjusted phandle into *phandle properties */
58 for_each_property_of_node(overlay, prop) {
60 if (of_prop_cmp(prop->name, "phandle") &&
61 of_prop_cmp(prop->name, "linux,phandle"))
67 phandle = be32_to_cpup(prop->value);
68 if (phandle == OF_PHANDLE_ILLEGAL)
71 *(__be32 *)prop->value = cpu_to_be32(overlay->phandle);
74 for_each_child_of_node(overlay, child)
75 adjust_overlay_phandles(child, phandle_delta);
78 static int update_usages_of_a_phandle_reference(struct device_node *overlay,
79 struct property *prop_fixup, phandle phandle)
81 struct device_node *refnode;
82 struct property *prop;
83 char *value, *cur, *end, *node_path, *prop_name, *s;
87 value = kmalloc(prop_fixup->length, GFP_KERNEL);
90 memcpy(value, prop_fixup->value, prop_fixup->length);
92 /* prop_fixup contains a list of tuples of path:property_name:offset */
93 end = value + prop_fixup->length;
94 for (cur = value; cur < end; cur += len + 1) {
113 err = kstrtoint(s, 10, &offset);
117 refnode = __of_find_node_by_full_path(of_node_get(overlay), node_path);
121 for_each_property_of_node(refnode, prop) {
122 if (!of_prop_cmp(prop->name, prop_name))
125 of_node_put(refnode);
132 if (offset < 0 || offset + sizeof(__be32) > prop->length) {
137 *(__be32 *)(prop->value + offset) = cpu_to_be32(phandle);
145 /* compare nodes taking into account that 'name' strips out the @ part */
146 static int node_name_cmp(const struct device_node *dn1,
147 const struct device_node *dn2)
149 const char *n1 = kbasename(dn1->full_name);
150 const char *n2 = kbasename(dn2->full_name);
152 return of_node_cmp(n1, n2);
156 * Adjust the local phandle references by the given phandle delta.
158 * Subtree @local_fixups, which is overlay node __local_fixups__,
159 * mirrors the fragment node structure at the root of the overlay.
161 * For each property in the fragments that contains a phandle reference,
162 * @local_fixups has a property of the same name that contains a list
163 * of offsets of the phandle reference(s) within the respective property
164 * value(s). The values at these offsets will be fixed up.
166 static int adjust_local_phandle_references(struct device_node *local_fixups,
167 struct device_node *overlay, int phandle_delta)
169 struct device_node *child, *overlay_child;
170 struct property *prop_fix, *prop;
178 for_each_property_of_node(local_fixups, prop_fix) {
180 /* skip properties added automatically */
181 if (!of_prop_cmp(prop_fix->name, "name") ||
182 !of_prop_cmp(prop_fix->name, "phandle") ||
183 !of_prop_cmp(prop_fix->name, "linux,phandle"))
186 if ((prop_fix->length % 4) != 0 || prop_fix->length == 0)
188 count = prop_fix->length / sizeof(__be32);
190 for_each_property_of_node(overlay, prop) {
191 if (!of_prop_cmp(prop->name, prop_fix->name))
198 for (i = 0; i < count; i++) {
199 off = be32_to_cpu(((__be32 *)prop_fix->value)[i]);
200 if ((off + 4) > prop->length)
203 phandle = be32_to_cpu(*(__be32 *)(prop->value + off));
204 phandle += phandle_delta;
205 *(__be32 *)(prop->value + off) = cpu_to_be32(phandle);
210 * These nested loops recurse down two subtrees in parallel, where the
211 * node names in the two subtrees match.
213 * The roots of the subtrees are the overlay's __local_fixups__ node
214 * and the overlay's root node.
216 for_each_child_of_node(local_fixups, child) {
218 for_each_child_of_node(overlay, overlay_child)
219 if (!node_name_cmp(child, overlay_child))
225 err = adjust_local_phandle_references(child, overlay_child,
235 * of_resolve_phandles - Relocate and resolve overlay against live tree
237 * @overlay: Pointer to devicetree overlay to relocate and resolve
239 * Modify (relocate) values of local phandles in @overlay to a range that
240 * does not conflict with the live expanded devicetree. Update references
241 * to the local phandles in @overlay. Update (resolve) phandle references
242 * in @overlay that refer to the live expanded devicetree.
244 * Phandle values in the live tree are in the range of
245 * 1 .. live_tree_max_phandle(). The range of phandle values in the overlay
246 * also begin with at 1. Adjust the phandle values in the overlay to begin
247 * at live_tree_max_phandle() + 1. Update references to the phandles to
248 * the adjusted phandle values.
250 * The name of each property in the "__fixups__" node in the overlay matches
251 * the name of a symbol (a label) in the live tree. The values of each
252 * property in the "__fixups__" node is a list of the property values in the
253 * overlay that need to be updated to contain the phandle reference
254 * corresponding to that symbol in the live tree. Update the references in
255 * the overlay with the phandle values in the live tree.
257 * @overlay must be detached.
259 * Resolving and applying @overlay to the live expanded devicetree must be
260 * protected by a mechanism to ensure that multiple overlays are processed
261 * in a single threaded manner so that multiple overlays will not relocate
262 * phandles to overlapping ranges. The mechanism to enforce this is not
265 * Return: %0 on success or a negative error value on error.
267 int of_resolve_phandles(struct device_node *overlay)
269 struct device_node *child, *local_fixups, *refnode;
270 struct device_node *tree_symbols, *overlay_fixups;
271 struct property *prop;
273 phandle phandle, phandle_delta;
279 pr_err("null overlay\n");
283 if (!of_node_check_flag(overlay, OF_DETACHED)) {
284 pr_err("overlay not detached\n");
289 phandle_delta = live_tree_max_phandle() + 1;
290 adjust_overlay_phandles(overlay, phandle_delta);
292 for_each_child_of_node(overlay, local_fixups)
293 if (!of_node_cmp(local_fixups->name, "__local_fixups__"))
296 err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta);
300 overlay_fixups = NULL;
302 for_each_child_of_node(overlay, child) {
303 if (!of_node_cmp(child->name, "__fixups__"))
304 overlay_fixups = child;
307 if (!overlay_fixups) {
312 tree_symbols = of_find_node_by_path("/__symbols__");
314 pr_err("no symbols in root of device tree.\n");
319 for_each_property_of_node(overlay_fixups, prop) {
321 /* skip properties added automatically */
322 if (!of_prop_cmp(prop->name, "name"))
325 err = of_property_read_string(tree_symbols,
326 prop->name, &refpath);
330 refnode = of_find_node_by_path(refpath);
336 phandle = refnode->phandle;
337 of_node_put(refnode);
339 err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
346 pr_err("overlay phandle fixup failed: %d\n", err);
347 of_node_put(tree_symbols);
351 EXPORT_SYMBOL_GPL(of_resolve_phandles);