xref: /openbmc/linux/drivers/of/resolver.c (revision 867a0e05)
1 /*
2  * Functions for dealing with DT resolution
3  *
4  * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
5  * Copyright (C) 2012 Texas Instruments Inc.
6  *
7  * This program is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU General Public License
9  * version 2 as published by the Free Software Foundation.
10  */
11 
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/string.h>
20 #include <linux/slab.h>
21 
22 /* illegal phandle value (set when unresolved) */
23 #define OF_PHANDLE_ILLEGAL	0xdeadbeef
24 
25 /**
26  * Find a node with the give full name by recursively following any of
27  * the child node links.
28  */
29 static struct device_node *__of_find_node_by_full_name(struct device_node *node,
30 		const char *full_name)
31 {
32 	struct device_node *child, *found;
33 
34 	if (node == NULL)
35 		return NULL;
36 
37 	/* check */
38 	if (of_node_cmp(node->full_name, full_name) == 0)
39 		return node;
40 
41 	for_each_child_of_node(node, child) {
42 		found = __of_find_node_by_full_name(child, full_name);
43 		if (found != NULL)
44 			return found;
45 	}
46 
47 	return NULL;
48 }
49 
50 /*
51  * Find live tree's maximum phandle value.
52  */
53 static phandle of_get_tree_max_phandle(void)
54 {
55 	struct device_node *node;
56 	phandle phandle;
57 	unsigned long flags;
58 
59 	/* now search recursively */
60 	raw_spin_lock_irqsave(&devtree_lock, flags);
61 	phandle = 0;
62 	for_each_of_allnodes(node) {
63 		if (node->phandle != OF_PHANDLE_ILLEGAL &&
64 				node->phandle > phandle)
65 			phandle = node->phandle;
66 	}
67 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
68 
69 	return phandle;
70 }
71 
72 /*
73  * Adjust a subtree's phandle values by a given delta.
74  * Makes sure not to just adjust the device node's phandle value,
75  * but modify the phandle properties values as well.
76  */
77 static void __of_adjust_tree_phandles(struct device_node *node,
78 		int phandle_delta)
79 {
80 	struct device_node *child;
81 	struct property *prop;
82 	phandle phandle;
83 
84 	/* first adjust the node's phandle direct value */
85 	if (node->phandle != 0 && node->phandle != OF_PHANDLE_ILLEGAL)
86 		node->phandle += phandle_delta;
87 
88 	/* now adjust phandle & linux,phandle values */
89 	for_each_property_of_node(node, prop) {
90 
91 		/* only look for these two */
92 		if (of_prop_cmp(prop->name, "phandle") != 0 &&
93 		    of_prop_cmp(prop->name, "linux,phandle") != 0)
94 			continue;
95 
96 		/* must be big enough */
97 		if (prop->length < 4)
98 			continue;
99 
100 		/* read phandle value */
101 		phandle = be32_to_cpup(prop->value);
102 		if (phandle == OF_PHANDLE_ILLEGAL)	/* unresolved */
103 			continue;
104 
105 		/* adjust */
106 		*(uint32_t *)prop->value = cpu_to_be32(node->phandle);
107 	}
108 
109 	/* now do the children recursively */
110 	for_each_child_of_node(node, child)
111 		__of_adjust_tree_phandles(child, phandle_delta);
112 }
113 
114 static int __of_adjust_phandle_ref(struct device_node *node,
115 		struct property *rprop, int value)
116 {
117 	phandle phandle;
118 	struct device_node *refnode;
119 	struct property *sprop;
120 	char *propval, *propcur, *propend, *nodestr, *propstr, *s;
121 	int offset, propcurlen;
122 	int err = 0;
123 
124 	/* make a copy */
125 	propval = kmalloc(rprop->length, GFP_KERNEL);
126 	if (!propval) {
127 		pr_err("%s: Could not copy value of '%s'\n",
128 				__func__, rprop->name);
129 		return -ENOMEM;
130 	}
131 	memcpy(propval, rprop->value, rprop->length);
132 
133 	propend = propval + rprop->length;
134 	for (propcur = propval; propcur < propend; propcur += propcurlen + 1) {
135 		propcurlen = strlen(propcur);
136 
137 		nodestr = propcur;
138 		s = strchr(propcur, ':');
139 		if (!s) {
140 			pr_err("%s: Illegal symbol entry '%s' (1)\n",
141 				__func__, propcur);
142 			err = -EINVAL;
143 			goto err_fail;
144 		}
145 		*s++ = '\0';
146 
147 		propstr = s;
148 		s = strchr(s, ':');
149 		if (!s) {
150 			pr_err("%s: Illegal symbol entry '%s' (2)\n",
151 				__func__, (char *)rprop->value);
152 			err = -EINVAL;
153 			goto err_fail;
154 		}
155 
156 		*s++ = '\0';
157 		err = kstrtoint(s, 10, &offset);
158 		if (err != 0) {
159 			pr_err("%s: Could get offset '%s'\n",
160 				__func__, (char *)rprop->value);
161 			goto err_fail;
162 		}
163 
164 		/* look into the resolve node for the full path */
165 		refnode = __of_find_node_by_full_name(node, nodestr);
166 		if (!refnode) {
167 			pr_warn("%s: Could not find refnode '%s'\n",
168 				__func__, (char *)rprop->value);
169 			continue;
170 		}
171 
172 		/* now find the property */
173 		for_each_property_of_node(refnode, sprop) {
174 			if (of_prop_cmp(sprop->name, propstr) == 0)
175 				break;
176 		}
177 
178 		if (!sprop) {
179 			pr_err("%s: Could not find property '%s'\n",
180 				__func__, (char *)rprop->value);
181 			err = -ENOENT;
182 			goto err_fail;
183 		}
184 
185 		phandle = value;
186 		*(__be32 *)(sprop->value + offset) = cpu_to_be32(phandle);
187 	}
188 
189 err_fail:
190 	kfree(propval);
191 	return err;
192 }
193 
194 /* compare nodes taking into account that 'name' strips out the @ part */
195 static int __of_node_name_cmp(const struct device_node *dn1,
196 		const struct device_node *dn2)
197 {
198 	const char *n1 = strrchr(dn1->full_name, '/') ? : "/";
199 	const char *n2 = strrchr(dn2->full_name, '/') ? : "/";
200 
201 	return of_node_cmp(n1, n2);
202 }
203 
204 /*
205  * Adjust the local phandle references by the given phandle delta.
206  * Assumes the existances of a __local_fixups__ node at the root.
207  * Assumes that __of_verify_tree_phandle_references has been called.
208  * Does not take any devtree locks so make sure you call this on a tree
209  * which is at the detached state.
210  */
211 static int __of_adjust_tree_phandle_references(struct device_node *node,
212 		struct device_node *target, int phandle_delta)
213 {
214 	struct device_node *child, *childtarget;
215 	struct property *rprop, *sprop;
216 	int err, i, count;
217 	unsigned int off;
218 	phandle phandle;
219 
220 	if (node == NULL)
221 		return 0;
222 
223 	for_each_property_of_node(node, rprop) {
224 
225 		/* skip properties added automatically */
226 		if (of_prop_cmp(rprop->name, "name") == 0 ||
227 		    of_prop_cmp(rprop->name, "phandle") == 0 ||
228 		    of_prop_cmp(rprop->name, "linux,phandle") == 0)
229 			continue;
230 
231 		if ((rprop->length % 4) != 0 || rprop->length == 0) {
232 			pr_err("%s: Illegal property (size) '%s' @%s\n",
233 					__func__, rprop->name, node->full_name);
234 			return -EINVAL;
235 		}
236 		count = rprop->length / sizeof(__be32);
237 
238 		/* now find the target property */
239 		for_each_property_of_node(target, sprop) {
240 			if (of_prop_cmp(sprop->name, rprop->name) == 0)
241 				break;
242 		}
243 
244 		if (sprop == NULL) {
245 			pr_err("%s: Could not find target property '%s' @%s\n",
246 					__func__, rprop->name, node->full_name);
247 			return -EINVAL;
248 		}
249 
250 		for (i = 0; i < count; i++) {
251 			off = be32_to_cpu(((__be32 *)rprop->value)[i]);
252 			/* make sure the offset doesn't overstep (even wrap) */
253 			if (off >= sprop->length ||
254 					(off + 4) > sprop->length) {
255 				pr_err("%s: Illegal property '%s' @%s\n",
256 						__func__, rprop->name,
257 						node->full_name);
258 				return -EINVAL;
259 			}
260 
261 			if (phandle_delta) {
262 				/* adjust */
263 				phandle = be32_to_cpu(*(__be32 *)(sprop->value + off));
264 				phandle += phandle_delta;
265 				*(__be32 *)(sprop->value + off) = cpu_to_be32(phandle);
266 			}
267 		}
268 	}
269 
270 	for_each_child_of_node(node, child) {
271 
272 		for_each_child_of_node(target, childtarget)
273 			if (__of_node_name_cmp(child, childtarget) == 0)
274 				break;
275 
276 		if (!childtarget) {
277 			pr_err("%s: Could not find target child '%s' @%s\n",
278 					__func__, child->name, node->full_name);
279 			return -EINVAL;
280 		}
281 
282 		err = __of_adjust_tree_phandle_references(child, childtarget,
283 				phandle_delta);
284 		if (err != 0)
285 			return err;
286 	}
287 
288 	return 0;
289 }
290 
291 /**
292  * of_resolve	- Resolve the given node against the live tree.
293  *
294  * @resolve:	Node to resolve
295  *
296  * Perform dynamic Device Tree resolution against the live tree
297  * to the given node to resolve. This depends on the live tree
298  * having a __symbols__ node, and the resolve node the __fixups__ &
299  * __local_fixups__ nodes (if needed).
300  * The result of the operation is a resolve node that it's contents
301  * are fit to be inserted or operate upon the live tree.
302  * Returns 0 on success or a negative error value on error.
303  */
304 int of_resolve_phandles(struct device_node *resolve)
305 {
306 	struct device_node *child, *childroot, *refnode;
307 	struct device_node *root_sym, *resolve_sym, *resolve_fix;
308 	struct property *rprop;
309 	const char *refpath;
310 	phandle phandle, phandle_delta;
311 	int err;
312 
313 	/* the resolve node must exist, and be detached */
314 	if (!resolve || !of_node_check_flag(resolve, OF_DETACHED))
315 		return -EINVAL;
316 
317 	/* first we need to adjust the phandles */
318 	phandle_delta = of_get_tree_max_phandle() + 1;
319 	__of_adjust_tree_phandles(resolve, phandle_delta);
320 
321 	/* locate the local fixups */
322 	childroot = NULL;
323 	for_each_child_of_node(resolve, childroot)
324 		if (of_node_cmp(childroot->name, "__local_fixups__") == 0)
325 			break;
326 
327 	if (childroot != NULL) {
328 		/* resolve root is guaranteed to be the '/' */
329 		err = __of_adjust_tree_phandle_references(childroot,
330 				resolve, 0);
331 		if (err != 0)
332 			return err;
333 
334 		BUG_ON(__of_adjust_tree_phandle_references(childroot,
335 				resolve, phandle_delta));
336 	}
337 
338 	root_sym = NULL;
339 	resolve_sym = NULL;
340 	resolve_fix = NULL;
341 
342 	/* this may fail (if no fixups are required) */
343 	root_sym = of_find_node_by_path("/__symbols__");
344 
345 	/* locate the symbols & fixups nodes on resolve */
346 	for_each_child_of_node(resolve, child) {
347 
348 		if (!resolve_sym &&
349 				of_node_cmp(child->name, "__symbols__") == 0)
350 			resolve_sym = child;
351 
352 		if (!resolve_fix &&
353 				of_node_cmp(child->name, "__fixups__") == 0)
354 			resolve_fix = child;
355 
356 		/* both found, don't bother anymore */
357 		if (resolve_sym && resolve_fix)
358 			break;
359 	}
360 
361 	/* we do allow for the case where no fixups are needed */
362 	if (!resolve_fix) {
363 		err = 0;	/* no error */
364 		goto out;
365 	}
366 
367 	/* we need to fixup, but no root symbols... */
368 	if (!root_sym) {
369 		err = -EINVAL;
370 		goto out;
371 	}
372 
373 	for_each_property_of_node(resolve_fix, rprop) {
374 
375 		/* skip properties added automatically */
376 		if (of_prop_cmp(rprop->name, "name") == 0)
377 			continue;
378 
379 		err = of_property_read_string(root_sym,
380 				rprop->name, &refpath);
381 		if (err != 0) {
382 			pr_err("%s: Could not find symbol '%s'\n",
383 					__func__, rprop->name);
384 			goto out;
385 		}
386 
387 		refnode = of_find_node_by_path(refpath);
388 		if (!refnode) {
389 			pr_err("%s: Could not find node by path '%s'\n",
390 					__func__, refpath);
391 			err = -ENOENT;
392 			goto out;
393 		}
394 
395 		phandle = refnode->phandle;
396 		of_node_put(refnode);
397 
398 		pr_debug("%s: %s phandle is 0x%08x\n",
399 				__func__, rprop->name, phandle);
400 
401 		err = __of_adjust_phandle_ref(resolve, rprop, phandle);
402 		if (err)
403 			break;
404 	}
405 
406 out:
407 	/* NULL is handled by of_node_put as NOP */
408 	of_node_put(root_sym);
409 
410 	return err;
411 }
412 EXPORT_SYMBOL_GPL(of_resolve_phandles);
413