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
live_tree_max_phandle(void)22 static 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
adjust_overlay_phandles(struct device_node * overlay,int phandle_delta)40 static 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
update_usages_of_a_phandle_reference(struct device_node * overlay,struct property * prop_fixup,phandle phandle)72 static 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
133 err_fail:
134 kfree(value);
135 return err;
136 }
137
138 /* compare nodes taking into account that 'name' strips out the @ part */
node_name_cmp(const struct device_node * dn1,const struct device_node * dn2)139 static 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 */
adjust_local_phandle_references(struct device_node * local_fixups,struct device_node * overlay,int phandle_delta)159 static 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 of_node_put(overlay_child);
211 break;
212 }
213
214 if (!overlay_child) {
215 of_node_put(child);
216 return -EINVAL;
217 }
218
219 err = adjust_local_phandle_references(child, overlay_child,
220 phandle_delta);
221 if (err) {
222 of_node_put(child);
223 return err;
224 }
225 }
226
227 return 0;
228 }
229
230 /**
231 * of_resolve_phandles - Relocate and resolve overlay against live tree
232 *
233 * @overlay: Pointer to devicetree overlay to relocate and resolve
234 *
235 * Modify (relocate) values of local phandles in @overlay to a range that
236 * does not conflict with the live expanded devicetree. Update references
237 * to the local phandles in @overlay. Update (resolve) phandle references
238 * in @overlay that refer to the live expanded devicetree.
239 *
240 * Phandle values in the live tree are in the range of
241 * 1 .. live_tree_max_phandle(). The range of phandle values in the overlay
242 * also begin with at 1. Adjust the phandle values in the overlay to begin
243 * at live_tree_max_phandle() + 1. Update references to the phandles to
244 * the adjusted phandle values.
245 *
246 * The name of each property in the "__fixups__" node in the overlay matches
247 * the name of a symbol (a label) in the live tree. The values of each
248 * property in the "__fixups__" node is a list of the property values in the
249 * overlay that need to be updated to contain the phandle reference
250 * corresponding to that symbol in the live tree. Update the references in
251 * the overlay with the phandle values in the live tree.
252 *
253 * @overlay must be detached.
254 *
255 * Resolving and applying @overlay to the live expanded devicetree must be
256 * protected by a mechanism to ensure that multiple overlays are processed
257 * in a single threaded manner so that multiple overlays will not relocate
258 * phandles to overlapping ranges. The mechanism to enforce this is not
259 * yet implemented.
260 *
261 * Return: %0 on success or a negative error value on error.
262 */
of_resolve_phandles(struct device_node * overlay)263 int of_resolve_phandles(struct device_node *overlay)
264 {
265 struct device_node *child, *local_fixups, *refnode;
266 struct device_node *tree_symbols, *overlay_fixups;
267 struct property *prop;
268 const char *refpath;
269 phandle phandle, phandle_delta;
270 int err;
271
272 tree_symbols = NULL;
273
274 if (!overlay) {
275 pr_err("null overlay\n");
276 err = -EINVAL;
277 goto out;
278 }
279
280 if (!of_node_check_flag(overlay, OF_DETACHED)) {
281 pr_err("overlay not detached\n");
282 err = -EINVAL;
283 goto out;
284 }
285
286 phandle_delta = live_tree_max_phandle() + 1;
287 adjust_overlay_phandles(overlay, phandle_delta);
288
289 for_each_child_of_node(overlay, local_fixups)
290 if (of_node_name_eq(local_fixups, "__local_fixups__"))
291 break;
292
293 err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta);
294 if (err)
295 goto out;
296
297 overlay_fixups = NULL;
298
299 for_each_child_of_node(overlay, child) {
300 if (of_node_name_eq(child, "__fixups__"))
301 overlay_fixups = child;
302 }
303
304 if (!overlay_fixups) {
305 err = 0;
306 goto out;
307 }
308
309 tree_symbols = of_find_node_by_path("/__symbols__");
310 if (!tree_symbols) {
311 pr_err("no symbols in root of device tree.\n");
312 err = -EINVAL;
313 goto out;
314 }
315
316 for_each_property_of_node(overlay_fixups, prop) {
317
318 /* skip properties added automatically */
319 if (!of_prop_cmp(prop->name, "name"))
320 continue;
321
322 err = of_property_read_string(tree_symbols,
323 prop->name, &refpath);
324 if (err) {
325 pr_err("node label '%s' not found in live devicetree symbols table\n",
326 prop->name);
327 goto out;
328 }
329
330 refnode = of_find_node_by_path(refpath);
331 if (!refnode) {
332 err = -ENOENT;
333 goto out;
334 }
335
336 phandle = refnode->phandle;
337 of_node_put(refnode);
338
339 err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
340 if (err)
341 break;
342 }
343
344 out:
345 if (err)
346 pr_err("overlay phandle fixup failed: %d\n", err);
347 of_node_put(tree_symbols);
348
349 return err;
350 }
351 EXPORT_SYMBOL_GPL(of_resolve_phandles);
352