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 | |
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 | |
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(p: 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(overlay: child, phandle_delta); |
70 | } |
71 | |
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(p: prop_fixup->value, size: 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, base: 10, res: &offset); |
107 | if (err) |
108 | goto err_fail; |
109 | |
110 | refnode = __of_find_node_by_full_path(node: of_node_get(node: overlay), path: 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(node: 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(objp: value); |
135 | return err; |
136 | } |
137 | |
138 | /* compare nodes taking into account that 'name' strips out the @ part */ |
139 | static int node_name_cmp(const struct device_node *dn1, |
140 | const struct device_node *dn2) |
141 | { |
142 | const char *n1 = kbasename(path: dn1->full_name); |
143 | const char *n2 = kbasename(path: 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 | */ |
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(var: prop->value + off, val: 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(dn1: child, dn2: overlay_child)) { |
210 | of_node_put(node: overlay_child); |
211 | break; |
212 | } |
213 | |
214 | if (!overlay_child) { |
215 | of_node_put(node: child); |
216 | return -EINVAL; |
217 | } |
218 | |
219 | err = adjust_local_phandle_references(local_fixups: child, overlay: overlay_child, |
220 | phandle_delta); |
221 | if (err) { |
222 | of_node_put(node: 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 | */ |
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(n: 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(np: local_fixups, name: "__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(np: child, name: "__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(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(np: tree_symbols, |
323 | propname: prop->name, out_string: &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(path: refpath); |
331 | if (!refnode) { |
332 | err = -ENOENT; |
333 | goto out; |
334 | } |
335 | |
336 | phandle = refnode->phandle; |
337 | of_node_put(node: refnode); |
338 | |
339 | err = update_usages_of_a_phandle_reference(overlay, prop_fixup: 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(node: tree_symbols); |
348 | |
349 | return err; |
350 | } |
351 | EXPORT_SYMBOL_GPL(of_resolve_phandles); |
352 | |