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/cleanup.h>
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/of.h>
15 #include <linux/of_device.h>
16 #include <linux/string.h>
17 #include <linux/ctype.h>
18 #include <linux/errno.h>
19 #include <linux/slab.h>
20
21 #include "of_private.h"
22
live_tree_max_phandle(void)23 static phandle live_tree_max_phandle(void)
24 {
25 struct device_node *node;
26 phandle phandle;
27 unsigned long flags;
28
29 raw_spin_lock_irqsave(&devtree_lock, flags);
30 phandle = 0;
31 for_each_of_allnodes(node) {
32 if (node->phandle != OF_PHANDLE_ILLEGAL &&
33 node->phandle > phandle)
34 phandle = node->phandle;
35 }
36 raw_spin_unlock_irqrestore(&devtree_lock, flags);
37
38 return phandle;
39 }
40
adjust_overlay_phandles(struct device_node * overlay,int phandle_delta)41 static void adjust_overlay_phandles(struct device_node *overlay,
42 int phandle_delta)
43 {
44 struct device_node *child;
45 const struct property *prop;
46 phandle phandle;
47
48 /* adjust node's phandle in node */
49 if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL)
50 overlay->phandle += phandle_delta;
51
52 /* copy adjusted phandle into *phandle properties */
53 for_each_property_of_node(overlay, prop) {
54
55 if (of_prop_cmp(prop->name, "phandle") &&
56 of_prop_cmp(prop->name, "linux,phandle"))
57 continue;
58
59 if (prop->length < 4)
60 continue;
61
62 phandle = be32_to_cpup(prop->value);
63 if (phandle == OF_PHANDLE_ILLEGAL)
64 continue;
65
66 *(__be32 *)prop->value = cpu_to_be32(overlay->phandle);
67 }
68
69 for_each_child_of_node(overlay, child)
70 adjust_overlay_phandles(child, phandle_delta);
71 }
72
update_usages_of_a_phandle_reference(struct device_node * overlay,const struct property * prop_fixup,phandle phandle)73 static int update_usages_of_a_phandle_reference(struct device_node *overlay,
74 const struct property *prop_fixup, phandle phandle)
75 {
76 struct device_node *refnode;
77 const struct property *prop;
78 char *value __free(kfree) = kmemdup(prop_fixup->value, prop_fixup->length, GFP_KERNEL);
79 char *cur, *end, *node_path, *prop_name, *s;
80 int offset, len;
81 int err = 0;
82
83 if (!value)
84 return -ENOMEM;
85
86 /* prop_fixup contains a list of tuples of path:property_name:offset */
87 end = value + prop_fixup->length;
88 for (cur = value; cur < end; cur += len + 1) {
89 len = strlen(cur);
90
91 node_path = cur;
92 s = strchr(cur, ':');
93 if (!s)
94 return -EINVAL;
95 *s++ = '\0';
96
97 prop_name = s;
98 s = strchr(s, ':');
99 if (!s)
100 return -EINVAL;
101 *s++ = '\0';
102
103 err = kstrtoint(s, 10, &offset);
104 if (err)
105 return err;
106
107 refnode = __of_find_node_by_full_path(of_node_get(overlay), node_path);
108 if (!refnode)
109 continue;
110
111 for_each_property_of_node(refnode, prop) {
112 if (!of_prop_cmp(prop->name, prop_name))
113 break;
114 }
115 of_node_put(refnode);
116
117 if (!prop)
118 return -ENOENT;
119
120 if (offset < 0 || offset + sizeof(__be32) > prop->length)
121 return -EINVAL;
122
123 *(__be32 *)(prop->value + offset) = cpu_to_be32(phandle);
124 }
125
126 return 0;
127 }
128
129 /* compare nodes taking into account that 'name' strips out the @ part */
node_name_cmp(const struct device_node * dn1,const struct device_node * dn2)130 static int node_name_cmp(const struct device_node *dn1,
131 const struct device_node *dn2)
132 {
133 const char *n1 = kbasename(dn1->full_name);
134 const char *n2 = kbasename(dn2->full_name);
135
136 return of_node_cmp(n1, n2);
137 }
138
139 /*
140 * Adjust the local phandle references by the given phandle delta.
141 *
142 * Subtree @local_fixups, which is overlay node __local_fixups__,
143 * mirrors the fragment node structure at the root of the overlay.
144 *
145 * For each property in the fragments that contains a phandle reference,
146 * @local_fixups has a property of the same name that contains a list
147 * of offsets of the phandle reference(s) within the respective property
148 * value(s). The values at these offsets will be fixed up.
149 */
adjust_local_phandle_references(const struct device_node * local_fixups,const struct device_node * overlay,int phandle_delta)150 static int adjust_local_phandle_references(const struct device_node *local_fixups,
151 const struct device_node *overlay, int phandle_delta)
152 {
153 struct device_node *overlay_child;
154 const struct property *prop_fix, *prop;
155 int err, i, count;
156 unsigned int off;
157
158 if (!local_fixups)
159 return 0;
160
161 for_each_property_of_node(local_fixups, prop_fix) {
162
163 /* skip properties added automatically */
164 if (!of_prop_cmp(prop_fix->name, "name") ||
165 !of_prop_cmp(prop_fix->name, "phandle") ||
166 !of_prop_cmp(prop_fix->name, "linux,phandle"))
167 continue;
168
169 if ((prop_fix->length % 4) != 0 || prop_fix->length == 0)
170 return -EINVAL;
171 count = prop_fix->length / sizeof(__be32);
172
173 for_each_property_of_node(overlay, prop) {
174 if (!of_prop_cmp(prop->name, prop_fix->name))
175 break;
176 }
177
178 if (!prop)
179 return -EINVAL;
180
181 for (i = 0; i < count; i++) {
182 off = be32_to_cpu(((__be32 *)prop_fix->value)[i]);
183 if ((off + 4) > prop->length)
184 return -EINVAL;
185
186 be32_add_cpu(prop->value + off, phandle_delta);
187 }
188 }
189
190 /*
191 * These nested loops recurse down two subtrees in parallel, where the
192 * node names in the two subtrees match.
193 *
194 * The roots of the subtrees are the overlay's __local_fixups__ node
195 * and the overlay's root node.
196 */
197 for_each_child_of_node_scoped(local_fixups, child) {
198
199 for_each_child_of_node(overlay, overlay_child)
200 if (!node_name_cmp(child, overlay_child)) {
201 of_node_put(overlay_child);
202 break;
203 }
204
205 if (!overlay_child)
206 return -EINVAL;
207
208 err = adjust_local_phandle_references(child, overlay_child,
209 phandle_delta);
210 if (err)
211 return err;
212 }
213
214 return 0;
215 }
216
217 /**
218 * of_resolve_phandles - Relocate and resolve overlay against live tree
219 *
220 * @overlay: Pointer to devicetree overlay to relocate and resolve
221 *
222 * Modify (relocate) values of local phandles in @overlay to a range that
223 * does not conflict with the live expanded devicetree. Update references
224 * to the local phandles in @overlay. Update (resolve) phandle references
225 * in @overlay that refer to the live expanded devicetree.
226 *
227 * Phandle values in the live tree are in the range of
228 * 1 .. live_tree_max_phandle(). The range of phandle values in the overlay
229 * also begin with at 1. Adjust the phandle values in the overlay to begin
230 * at live_tree_max_phandle() + 1. Update references to the phandles to
231 * the adjusted phandle values.
232 *
233 * The name of each property in the "__fixups__" node in the overlay matches
234 * the name of a symbol (a label) in the live tree. The values of each
235 * property in the "__fixups__" node is a list of the property values in the
236 * overlay that need to be updated to contain the phandle reference
237 * corresponding to that symbol in the live tree. Update the references in
238 * the overlay with the phandle values in the live tree.
239 *
240 * @overlay must be detached.
241 *
242 * Resolving and applying @overlay to the live expanded devicetree must be
243 * protected by a mechanism to ensure that multiple overlays are processed
244 * in a single threaded manner so that multiple overlays will not relocate
245 * phandles to overlapping ranges. The mechanism to enforce this is not
246 * yet implemented.
247 *
248 * Return: %0 on success or a negative error value on error.
249 */
of_resolve_phandles(struct device_node * overlay)250 int of_resolve_phandles(struct device_node *overlay)
251 {
252 struct device_node *child, *local_fixups, *refnode;
253 struct device_node *tree_symbols, *overlay_fixups;
254 struct property *prop;
255 const char *refpath;
256 phandle phandle, phandle_delta;
257 int err;
258
259 tree_symbols = NULL;
260
261 if (!overlay) {
262 pr_err("null overlay\n");
263 err = -EINVAL;
264 goto out;
265 }
266
267 if (!of_node_check_flag(overlay, OF_DETACHED)) {
268 pr_err("overlay not detached\n");
269 err = -EINVAL;
270 goto out;
271 }
272
273 phandle_delta = live_tree_max_phandle() + 1;
274 adjust_overlay_phandles(overlay, phandle_delta);
275
276 for_each_child_of_node(overlay, local_fixups)
277 if (of_node_name_eq(local_fixups, "__local_fixups__"))
278 break;
279
280 err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta);
281 if (err)
282 goto out;
283
284 overlay_fixups = NULL;
285
286 for_each_child_of_node(overlay, child) {
287 if (of_node_name_eq(child, "__fixups__"))
288 overlay_fixups = child;
289 }
290
291 if (!overlay_fixups) {
292 err = 0;
293 goto out;
294 }
295
296 tree_symbols = of_find_node_by_path("/__symbols__");
297 if (!tree_symbols) {
298 pr_err("no symbols in root of device tree.\n");
299 err = -EINVAL;
300 goto out;
301 }
302
303 for_each_property_of_node(overlay_fixups, prop) {
304
305 /* skip properties added automatically */
306 if (!of_prop_cmp(prop->name, "name"))
307 continue;
308
309 err = of_property_read_string(tree_symbols,
310 prop->name, &refpath);
311 if (err) {
312 pr_err("node label '%s' not found in live devicetree symbols table\n",
313 prop->name);
314 goto out;
315 }
316
317 refnode = of_find_node_by_path(refpath);
318 if (!refnode) {
319 err = -ENOENT;
320 goto out;
321 }
322
323 phandle = refnode->phandle;
324 of_node_put(refnode);
325
326 err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
327 if (err)
328 break;
329 }
330
331 out:
332 if (err)
333 pr_err("overlay phandle fixup failed: %d\n", err);
334 of_node_put(tree_symbols);
335
336 return err;
337 }
338 EXPORT_SYMBOL_GPL(of_resolve_phandles);
339