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
23static 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
41static void adjust_overlay_phandles(struct device_node *overlay,
42		int phandle_delta)
43{
44	struct device_node *child;
45	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
73static int update_usages_of_a_phandle_reference(struct device_node *overlay,
74		struct property *prop_fixup, phandle phandle)
75{
76	struct device_node *refnode;
77	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 */
130static 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 */
150static int adjust_local_phandle_references(struct device_node *local_fixups,
151		struct device_node *overlay, int phandle_delta)
152{
153	struct device_node *child, *overlay_child;
154	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(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			of_node_put(child);
207			return -EINVAL;
208		}
209
210		err = adjust_local_phandle_references(child, overlay_child,
211				phandle_delta);
212		if (err) {
213			of_node_put(child);
214			return err;
215		}
216	}
217
218	return 0;
219}
220
221/**
222 * of_resolve_phandles - Relocate and resolve overlay against live tree
223 *
224 * @overlay:	Pointer to devicetree overlay to relocate and resolve
225 *
226 * Modify (relocate) values of local phandles in @overlay to a range that
227 * does not conflict with the live expanded devicetree.  Update references
228 * to the local phandles in @overlay.  Update (resolve) phandle references
229 * in @overlay that refer to the live expanded devicetree.
230 *
231 * Phandle values in the live tree are in the range of
232 * 1 .. live_tree_max_phandle().  The range of phandle values in the overlay
233 * also begin with at 1.  Adjust the phandle values in the overlay to begin
234 * at live_tree_max_phandle() + 1.  Update references to the phandles to
235 * the adjusted phandle values.
236 *
237 * The name of each property in the "__fixups__" node in the overlay matches
238 * the name of a symbol (a label) in the live tree.  The values of each
239 * property in the "__fixups__" node is a list of the property values in the
240 * overlay that need to be updated to contain the phandle reference
241 * corresponding to that symbol in the live tree.  Update the references in
242 * the overlay with the phandle values in the live tree.
243 *
244 * @overlay must be detached.
245 *
246 * Resolving and applying @overlay to the live expanded devicetree must be
247 * protected by a mechanism to ensure that multiple overlays are processed
248 * in a single threaded manner so that multiple overlays will not relocate
249 * phandles to overlapping ranges.  The mechanism to enforce this is not
250 * yet implemented.
251 *
252 * Return: %0 on success or a negative error value on error.
253 */
254int of_resolve_phandles(struct device_node *overlay)
255{
256	struct device_node *child, *local_fixups, *refnode;
257	struct device_node *tree_symbols, *overlay_fixups;
258	struct property *prop;
259	const char *refpath;
260	phandle phandle, phandle_delta;
261	int err;
262
263	tree_symbols = NULL;
264
265	if (!overlay) {
266		pr_err("null overlay\n");
267		err = -EINVAL;
268		goto out;
269	}
270
271	if (!of_node_check_flag(overlay, OF_DETACHED)) {
272		pr_err("overlay not detached\n");
273		err = -EINVAL;
274		goto out;
275	}
276
277	phandle_delta = live_tree_max_phandle() + 1;
278	adjust_overlay_phandles(overlay, phandle_delta);
279
280	for_each_child_of_node(overlay, local_fixups)
281		if (of_node_name_eq(local_fixups, "__local_fixups__"))
282			break;
283
284	err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta);
285	if (err)
286		goto out;
287
288	overlay_fixups = NULL;
289
290	for_each_child_of_node(overlay, child) {
291		if (of_node_name_eq(child, "__fixups__"))
292			overlay_fixups = child;
293	}
294
295	if (!overlay_fixups) {
296		err = 0;
297		goto out;
298	}
299
300	tree_symbols = of_find_node_by_path("/__symbols__");
301	if (!tree_symbols) {
302		pr_err("no symbols in root of device tree.\n");
303		err = -EINVAL;
304		goto out;
305	}
306
307	for_each_property_of_node(overlay_fixups, prop) {
308
309		/* skip properties added automatically */
310		if (!of_prop_cmp(prop->name, "name"))
311			continue;
312
313		err = of_property_read_string(tree_symbols,
314				prop->name, &refpath);
315		if (err) {
316			pr_err("node label '%s' not found in live devicetree symbols table\n",
317			       prop->name);
318			goto out;
319		}
320
321		refnode = of_find_node_by_path(refpath);
322		if (!refnode) {
323			err = -ENOENT;
324			goto out;
325		}
326
327		phandle = refnode->phandle;
328		of_node_put(refnode);
329
330		err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
331		if (err)
332			break;
333	}
334
335out:
336	if (err)
337		pr_err("overlay phandle fixup failed: %d\n", err);
338	of_node_put(tree_symbols);
339
340	return err;
341}
342EXPORT_SYMBOL_GPL(of_resolve_phandles);
343