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 (is_pseudo_property(prop_fix->name))
165 continue;
166
167 if ((prop_fix->length % 4) != 0 || prop_fix->length == 0)
168 return -EINVAL;
169 count = prop_fix->length / sizeof(__be32);
170
171 for_each_property_of_node(overlay, prop) {
172 if (!of_prop_cmp(prop->name, prop_fix->name))
173 break;
174 }
175
176 if (!prop)
177 return -EINVAL;
178
179 for (i = 0; i < count; i++) {
180 off = be32_to_cpu(((__be32 *)prop_fix->value)[i]);
181 if ((off + 4) > prop->length)
182 return -EINVAL;
183
184 be32_add_cpu(prop->value + off, phandle_delta);
185 }
186 }
187
188 /*
189 * These nested loops recurse down two subtrees in parallel, where the
190 * node names in the two subtrees match.
191 *
192 * The roots of the subtrees are the overlay's __local_fixups__ node
193 * and the overlay's root node.
194 */
195 for_each_child_of_node_scoped(local_fixups, child) {
196
197 for_each_child_of_node(overlay, overlay_child)
198 if (!node_name_cmp(child, overlay_child)) {
199 of_node_put(overlay_child);
200 break;
201 }
202
203 if (!overlay_child)
204 return -EINVAL;
205
206 err = adjust_local_phandle_references(child, overlay_child,
207 phandle_delta);
208 if (err)
209 return err;
210 }
211
212 return 0;
213 }
214
215 /**
216 * of_resolve_phandles - Relocate and resolve overlay against live tree
217 *
218 * @overlay: Pointer to devicetree overlay to relocate and resolve
219 *
220 * Modify (relocate) values of local phandles in @overlay to a range that
221 * does not conflict with the live expanded devicetree. Update references
222 * to the local phandles in @overlay. Update (resolve) phandle references
223 * in @overlay that refer to the live expanded devicetree.
224 *
225 * Phandle values in the live tree are in the range of
226 * 1 .. live_tree_max_phandle(). The range of phandle values in the overlay
227 * also begin with at 1. Adjust the phandle values in the overlay to begin
228 * at live_tree_max_phandle() + 1. Update references to the phandles to
229 * the adjusted phandle values.
230 *
231 * The name of each property in the "__fixups__" node in the overlay matches
232 * the name of a symbol (a label) in the live tree. The values of each
233 * property in the "__fixups__" node is a list of the property values in the
234 * overlay that need to be updated to contain the phandle reference
235 * corresponding to that symbol in the live tree. Update the references in
236 * the overlay with the phandle values in the live tree.
237 *
238 * @overlay must be detached.
239 *
240 * Resolving and applying @overlay to the live expanded devicetree must be
241 * protected by a mechanism to ensure that multiple overlays are processed
242 * in a single threaded manner so that multiple overlays will not relocate
243 * phandles to overlapping ranges. The mechanism to enforce this is not
244 * yet implemented.
245 *
246 * Return: %0 on success or a negative error value on error.
247 */
of_resolve_phandles(struct device_node * overlay)248 int of_resolve_phandles(struct device_node *overlay)
249 {
250 struct device_node *child, *refnode;
251 struct device_node *overlay_fixups;
252 struct device_node __free(device_node) *local_fixups = NULL;
253 struct property *prop;
254 const char *refpath;
255 phandle phandle, phandle_delta;
256 int err;
257
258 if (!overlay) {
259 pr_err("null overlay\n");
260 return -EINVAL;
261 }
262
263 if (!of_node_check_flag(overlay, OF_DETACHED)) {
264 pr_err("overlay not detached\n");
265 return -EINVAL;
266 }
267
268 phandle_delta = live_tree_max_phandle() + 1;
269 adjust_overlay_phandles(overlay, phandle_delta);
270
271 for_each_child_of_node(overlay, local_fixups)
272 if (of_node_name_eq(local_fixups, "__local_fixups__"))
273 break;
274
275 err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta);
276 if (err)
277 return err;
278
279 overlay_fixups = NULL;
280
281 for_each_child_of_node(overlay, child) {
282 if (of_node_name_eq(child, "__fixups__"))
283 overlay_fixups = child;
284 }
285
286 if (!overlay_fixups)
287 return 0;
288
289 struct device_node __free(device_node) *tree_symbols = of_find_node_by_path("/__symbols__");
290 if (!tree_symbols) {
291 pr_err("no symbols in root of device tree.\n");
292 return -EINVAL;
293 }
294
295 for_each_property_of_node(overlay_fixups, prop) {
296
297 /* skip properties added automatically */
298 if (!of_prop_cmp(prop->name, "name"))
299 continue;
300
301 err = of_property_read_string(tree_symbols,
302 prop->name, &refpath);
303 if (err) {
304 pr_err("node label '%s' not found in live devicetree symbols table\n",
305 prop->name);
306 return err;
307 }
308
309 refnode = of_find_node_by_path(refpath);
310 if (!refnode)
311 return -ENOENT;
312
313 phandle = refnode->phandle;
314 of_node_put(refnode);
315
316 err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
317 if (err)
318 break;
319 }
320
321 if (err)
322 pr_err("overlay phandle fixup failed: %d\n", err);
323 return err;
324 }
325 EXPORT_SYMBOL_GPL(of_resolve_phandles);
326