1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Functions for dealing with DT resolution
4 *
5 * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
6 * Copyright (C) 2012 Texas Instruments Inc.
7 */
8
9#define pr_fmt(fmt) "OF: resolver: " fmt
10
11#include <linux/kernel.h>
12#include <linux/module.h>
13#include <linux/of.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>
19
20#include "of_private.h"
21
22static phandle live_tree_max_phandle(void)
23{
24 struct device_node *node;
25 phandle phandle;
26 unsigned long flags;
27
28 raw_spin_lock_irqsave(&devtree_lock, flags);
29 phandle = 0;
30 for_each_of_allnodes(node) {
31 if (node->phandle != OF_PHANDLE_ILLEGAL &&
32 node->phandle > phandle)
33 phandle = node->phandle;
34 }
35 raw_spin_unlock_irqrestore(&devtree_lock, flags);
36
37 return phandle;
38}
39
40static void adjust_overlay_phandles(struct device_node *overlay,
41 int phandle_delta)
42{
43 struct device_node *child;
44 struct property *prop;
45 phandle phandle;
46
47 /* adjust node's phandle in node */
48 if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL)
49 overlay->phandle += phandle_delta;
50
51 /* copy adjusted phandle into *phandle properties */
52 for_each_property_of_node(overlay, prop) {
53
54 if (of_prop_cmp(prop->name, "phandle") &&
55 of_prop_cmp(prop->name, "linux,phandle"))
56 continue;
57
58 if (prop->length < 4)
59 continue;
60
61 phandle = be32_to_cpup(prop->value);
62 if (phandle == OF_PHANDLE_ILLEGAL)
63 continue;
64
65 *(__be32 *)prop->value = cpu_to_be32(overlay->phandle);
66 }
67
68 for_each_child_of_node(overlay, child)
69 adjust_overlay_phandles(child, phandle_delta);
70}
71
72static int update_usages_of_a_phandle_reference(struct device_node *overlay,
73 struct property *prop_fixup, phandle phandle)
74{
75 struct device_node *refnode;
76 struct property *prop;
77 char *value, *cur, *end, *node_path, *prop_name, *s;
78 int offset, len;
79 int err = 0;
80
81 value = kmemdup(prop_fixup->value, prop_fixup->length, GFP_KERNEL);
82 if (!value)
83 return -ENOMEM;
84
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) {
88 len = strlen(cur);
89
90 node_path = cur;
91 s = strchr(cur, ':');
92 if (!s) {
93 err = -EINVAL;
94 goto err_fail;
95 }
96 *s++ = '\0';
97
98 prop_name = s;
99 s = strchr(s, ':');
100 if (!s) {
101 err = -EINVAL;
102 goto err_fail;
103 }
104 *s++ = '\0';
105
106 err = kstrtoint(s, 10, &offset);
107 if (err)
108 goto err_fail;
109
110 refnode = __of_find_node_by_full_path(of_node_get(overlay), node_path);
111 if (!refnode)
112 continue;
113
114 for_each_property_of_node(refnode, prop) {
115 if (!of_prop_cmp(prop->name, prop_name))
116 break;
117 }
118 of_node_put(refnode);
119
120 if (!prop) {
121 err = -ENOENT;
122 goto err_fail;
123 }
124
125 if (offset < 0 || offset + sizeof(__be32) > prop->length) {
126 err = -EINVAL;
127 goto err_fail;
128 }
129
130 *(__be32 *)(prop->value + offset) = cpu_to_be32(phandle);
131 }
132
133err_fail:
134 kfree(value);
135 return err;
136}
137
138/* compare nodes taking into account that 'name' strips out the @ part */
139static int node_name_cmp(const struct device_node *dn1,
140 const struct device_node *dn2)
141{
142 const char *n1 = kbasename(dn1->full_name);
143 const char *n2 = kbasename(dn2->full_name);
144
145 return of_node_cmp(n1, n2);
146}
147
148/*
149 * Adjust the local phandle references by the given phandle delta.
150 *
151 * Subtree @local_fixups, which is overlay node __local_fixups__,
152 * mirrors the fragment node structure at the root of the overlay.
153 *
154 * For each property in the fragments that contains a phandle reference,
155 * @local_fixups has a property of the same name that contains a list
156 * of offsets of the phandle reference(s) within the respective property
157 * value(s). The values at these offsets will be fixed up.
158 */
159static int adjust_local_phandle_references(struct device_node *local_fixups,
160 struct device_node *overlay, int phandle_delta)
161{
162 struct device_node *child, *overlay_child;
163 struct property *prop_fix, *prop;
164 int err, i, count;
165 unsigned int off;
166
167 if (!local_fixups)
168 return 0;
169
170 for_each_property_of_node(local_fixups, prop_fix) {
171
172 /* skip properties added automatically */
173 if (!of_prop_cmp(prop_fix->name, "name") ||
174 !of_prop_cmp(prop_fix->name, "phandle") ||
175 !of_prop_cmp(prop_fix->name, "linux,phandle"))
176 continue;
177
178 if ((prop_fix->length % 4) != 0 || prop_fix->length == 0)
179 return -EINVAL;
180 count = prop_fix->length / sizeof(__be32);
181
182 for_each_property_of_node(overlay, prop) {
183 if (!of_prop_cmp(prop->name, prop_fix->name))
184 break;
185 }
186
187 if (!prop)
188 return -EINVAL;
189
190 for (i = 0; i < count; i++) {
191 off = be32_to_cpu(((__be32 *)prop_fix->value)[i]);
192 if ((off + 4) > prop->length)
193 return -EINVAL;
194
195 be32_add_cpu(prop->value + off, phandle_delta);
196 }
197 }
198
199 /*
200 * These nested loops recurse down two subtrees in parallel, where the
201 * node names in the two subtrees match.
202 *
203 * The roots of the subtrees are the overlay's __local_fixups__ node
204 * and the overlay's root node.
205 */
206 for_each_child_of_node(local_fixups, child) {
207
208 for_each_child_of_node(overlay, overlay_child)
209 if (!node_name_cmp(child, overlay_child))
210 break;
211
212 if (!overlay_child)
213 return -EINVAL;
214
215 err = adjust_local_phandle_references(child, overlay_child,
216 phandle_delta);
217 if (err)
218 return err;
219 }
220
221 return 0;
222}
223
224/**
225 * of_resolve_phandles - Relocate and resolve overlay against live tree
226 *
227 * @overlay: Pointer to devicetree overlay to relocate and resolve
228 *
229 * Modify (relocate) values of local phandles in @overlay to a range that
230 * does not conflict with the live expanded devicetree. Update references
231 * to the local phandles in @overlay. Update (resolve) phandle references
232 * in @overlay that refer to the live expanded devicetree.
233 *
234 * Phandle values in the live tree are in the range of
235 * 1 .. live_tree_max_phandle(). The range of phandle values in the overlay
236 * also begin with at 1. Adjust the phandle values in the overlay to begin
237 * at live_tree_max_phandle() + 1. Update references to the phandles to
238 * the adjusted phandle values.
239 *
240 * The name of each property in the "__fixups__" node in the overlay matches
241 * the name of a symbol (a label) in the live tree. The values of each
242 * property in the "__fixups__" node is a list of the property values in the
243 * overlay that need to be updated to contain the phandle reference
244 * corresponding to that symbol in the live tree. Update the references in
245 * the overlay with the phandle values in the live tree.
246 *
247 * @overlay must be detached.
248 *
249 * Resolving and applying @overlay to the live expanded devicetree must be
250 * protected by a mechanism to ensure that multiple overlays are processed
251 * in a single threaded manner so that multiple overlays will not relocate
252 * phandles to overlapping ranges. The mechanism to enforce this is not
253 * yet implemented.
254 *
255 * Return: %0 on success or a negative error value on error.
256 */
257int of_resolve_phandles(struct device_node *overlay)
258{
259 struct device_node *child, *local_fixups, *refnode;
260 struct device_node *tree_symbols, *overlay_fixups;
261 struct property *prop;
262 const char *refpath;
263 phandle phandle, phandle_delta;
264 int err;
265
266 tree_symbols = NULL;
267
268 if (!overlay) {
269 pr_err("null overlay\n");
270 err = -EINVAL;
271 goto out;
272 }
273
274 if (!of_node_check_flag(overlay, OF_DETACHED)) {
275 pr_err("overlay not detached\n");
276 err = -EINVAL;
277 goto out;
278 }
279
280 phandle_delta = live_tree_max_phandle() + 1;
281 adjust_overlay_phandles(overlay, phandle_delta);
282
283 for_each_child_of_node(overlay, local_fixups)
284 if (of_node_name_eq(local_fixups, "__local_fixups__"))
285 break;
286
287 err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta);
288 if (err)
289 goto out;
290
291 overlay_fixups = NULL;
292
293 for_each_child_of_node(overlay, child) {
294 if (of_node_name_eq(child, "__fixups__"))
295 overlay_fixups = child;
296 }
297
298 if (!overlay_fixups) {
299 err = 0;
300 goto out;
301 }
302
303 tree_symbols = of_find_node_by_path("/__symbols__");
304 if (!tree_symbols) {
305 pr_err("no symbols in root of device tree.\n");
306 err = -EINVAL;
307 goto out;
308 }
309
310 for_each_property_of_node(overlay_fixups, prop) {
311
312 /* skip properties added automatically */
313 if (!of_prop_cmp(prop->name, "name"))
314 continue;
315
316 err = of_property_read_string(tree_symbols,
317 prop->name, &refpath);
318 if (err)
319 goto out;
320
321 refnode = of_find_node_by_path(refpath);
322 if (!refnode) {
323 err = -ENOENT;
324 goto out;
325 }
326
327 phandle = refnode->phandle;
328 of_node_put(refnode);
329
330 err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
331 if (err)
332 break;
333 }
334
335out:
336 if (err)
337 pr_err("overlay phandle fixup failed: %d\n", err);
338 of_node_put(tree_symbols);
339
340 return err;
341}
342EXPORT_SYMBOL_GPL(of_resolve_phandles);
343