summaryrefslogtreecommitdiff
path: root/drivers/of/resolver.c
blob: 2780928764a4f10a9a8c2ead6072c2f88844d165 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
// SPDX-License-Identifier: GPL-2.0
/*
 * Functions for dealing with DT resolution
 *
 * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
 * Copyright (C) 2012 Texas Instruments Inc.
 */

#define pr_fmt(fmt)	"OF: resolver: " fmt

#include <linux/cleanup.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/slab.h>

#include "of_private.h"

static phandle live_tree_max_phandle(void)
{
	struct device_node *node;
	phandle phandle;
	unsigned long flags;

	raw_spin_lock_irqsave(&devtree_lock, flags);
	phandle = 0;
	for_each_of_allnodes(node) {
		if (node->phandle != OF_PHANDLE_ILLEGAL &&
				node->phandle > phandle)
			phandle = node->phandle;
	}
	raw_spin_unlock_irqrestore(&devtree_lock, flags);

	return phandle;
}

static void adjust_overlay_phandles(struct device_node *overlay,
		int phandle_delta)
{
	struct device_node *child;
	struct property *prop;
	phandle phandle;

	/* adjust node's phandle in node */
	if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL)
		overlay->phandle += phandle_delta;

	/* copy adjusted phandle into *phandle properties */
	for_each_property_of_node(overlay, prop) {

		if (of_prop_cmp(prop->name, "phandle") &&
		    of_prop_cmp(prop->name, "linux,phandle"))
			continue;

		if (prop->length < 4)
			continue;

		phandle = be32_to_cpup(prop->value);
		if (phandle == OF_PHANDLE_ILLEGAL)
			continue;

		*(__be32 *)prop->value = cpu_to_be32(overlay->phandle);
	}

	for_each_child_of_node(overlay, child)
		adjust_overlay_phandles(child, phandle_delta);
}

static int update_usages_of_a_phandle_reference(struct device_node *overlay,
		struct property *prop_fixup, phandle phandle)
{
	struct device_node *refnode;
	struct property *prop;
	char *value __free(kfree) = kmemdup(prop_fixup->value, prop_fixup->length, GFP_KERNEL);
	char *cur, *end, *node_path, *prop_name, *s;
	int offset, len;
	int err = 0;

	if (!value)
		return -ENOMEM;

	/* prop_fixup contains a list of tuples of path:property_name:offset */
	end = value + prop_fixup->length;
	for (cur = value; cur < end; cur += len + 1) {
		len = strlen(cur);

		node_path = cur;
		s = strchr(cur, ':');
		if (!s)
			return -EINVAL;
		*s++ = '\0';

		prop_name = s;
		s = strchr(s, ':');
		if (!s)
			return -EINVAL;
		*s++ = '\0';

		err = kstrtoint(s, 10, &offset);
		if (err)
			return err;

		refnode = __of_find_node_by_full_path(of_node_get(overlay), node_path);
		if (!refnode)
			continue;

		for_each_property_of_node(refnode, prop) {
			if (!of_prop_cmp(prop->name, prop_name))
				break;
		}
		of_node_put(refnode);

		if (!prop)
			return -ENOENT;

		if (offset < 0 || offset + sizeof(__be32) > prop->length)
			return -EINVAL;

		*(__be32 *)(prop->value + offset) = cpu_to_be32(phandle);
	}

	return 0;
}

/* compare nodes taking into account that 'name' strips out the @ part */
static int node_name_cmp(const struct device_node *dn1,
		const struct device_node *dn2)
{
	const char *n1 = kbasename(dn1->full_name);
	const char *n2 = kbasename(dn2->full_name);

	return of_node_cmp(n1, n2);
}

/*
 * Adjust the local phandle references by the given phandle delta.
 *
 * Subtree @local_fixups, which is overlay node __local_fixups__,
 * mirrors the fragment node structure at the root of the overlay.
 *
 * For each property in the fragments that contains a phandle reference,
 * @local_fixups has a property of the same name that contains a list
 * of offsets of the phandle reference(s) within the respective property
 * value(s).  The values at these offsets will be fixed up.
 */
static int adjust_local_phandle_references(struct device_node *local_fixups,
		struct device_node *overlay, int phandle_delta)
{
	struct device_node *child, *overlay_child;
	struct property *prop_fix, *prop;
	int err, i, count;
	unsigned int off;

	if (!local_fixups)
		return 0;

	for_each_property_of_node(local_fixups, prop_fix) {

		/* skip properties added automatically */
		if (!of_prop_cmp(prop_fix->name, "name") ||
		    !of_prop_cmp(prop_fix->name, "phandle") ||
		    !of_prop_cmp(prop_fix->name, "linux,phandle"))
			continue;

		if ((prop_fix->length % 4) != 0 || prop_fix->length == 0)
			return -EINVAL;
		count = prop_fix->length / sizeof(__be32);

		for_each_property_of_node(overlay, prop) {
			if (!of_prop_cmp(prop->name, prop_fix->name))
				break;
		}

		if (!prop)
			return -EINVAL;

		for (i = 0; i < count; i++) {
			off = be32_to_cpu(((__be32 *)prop_fix->value)[i]);
			if ((off + 4) > prop->length)
				return -EINVAL;

			be32_add_cpu(prop->value + off, phandle_delta);
		}
	}

	/*
	 * These nested loops recurse down two subtrees in parallel, where the
	 * node names in the two subtrees match.
	 *
	 * The roots of the subtrees are the overlay's __local_fixups__ node
	 * and the overlay's root node.
	 */
	for_each_child_of_node(local_fixups, child) {

		for_each_child_of_node(overlay, overlay_child)
			if (!node_name_cmp(child, overlay_child)) {
				of_node_put(overlay_child);
				break;
			}

		if (!overlay_child) {
			of_node_put(child);
			return -EINVAL;
		}

		err = adjust_local_phandle_references(child, overlay_child,
				phandle_delta);
		if (err) {
			of_node_put(child);
			return err;
		}
	}

	return 0;
}

/**
 * of_resolve_phandles - Relocate and resolve overlay against live tree
 *
 * @overlay:	Pointer to devicetree overlay to relocate and resolve
 *
 * Modify (relocate) values of local phandles in @overlay to a range that
 * does not conflict with the live expanded devicetree.  Update references
 * to the local phandles in @overlay.  Update (resolve) phandle references
 * in @overlay that refer to the live expanded devicetree.
 *
 * Phandle values in the live tree are in the range of
 * 1 .. live_tree_max_phandle().  The range of phandle values in the overlay
 * also begin with at 1.  Adjust the phandle values in the overlay to begin
 * at live_tree_max_phandle() + 1.  Update references to the phandles to
 * the adjusted phandle values.
 *
 * The name of each property in the "__fixups__" node in the overlay matches
 * the name of a symbol (a label) in the live tree.  The values of each
 * property in the "__fixups__" node is a list of the property values in the
 * overlay that need to be updated to contain the phandle reference
 * corresponding to that symbol in the live tree.  Update the references in
 * the overlay with the phandle values in the live tree.
 *
 * @overlay must be detached.
 *
 * Resolving and applying @overlay to the live expanded devicetree must be
 * protected by a mechanism to ensure that multiple overlays are processed
 * in a single threaded manner so that multiple overlays will not relocate
 * phandles to overlapping ranges.  The mechanism to enforce this is not
 * yet implemented.
 *
 * Return: %0 on success or a negative error value on error.
 */
int of_resolve_phandles(struct device_node *overlay)
{
	struct device_node *child, *local_fixups, *refnode;
	struct device_node *tree_symbols, *overlay_fixups;
	struct property *prop;
	const char *refpath;
	phandle phandle, phandle_delta;
	int err;

	tree_symbols = NULL;

	if (!overlay) {
		pr_err("null overlay\n");
		err = -EINVAL;
		goto out;
	}

	if (!of_node_check_flag(overlay, OF_DETACHED)) {
		pr_err("overlay not detached\n");
		err = -EINVAL;
		goto out;
	}

	phandle_delta = live_tree_max_phandle() + 1;
	adjust_overlay_phandles(overlay, phandle_delta);

	for_each_child_of_node(overlay, local_fixups)
		if (of_node_name_eq(local_fixups, "__local_fixups__"))
			break;

	err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta);
	if (err)
		goto out;

	overlay_fixups = NULL;

	for_each_child_of_node(overlay, child) {
		if (of_node_name_eq(child, "__fixups__"))
			overlay_fixups = child;
	}

	if (!overlay_fixups) {
		err = 0;
		goto out;
	}

	tree_symbols = of_find_node_by_path("/__symbols__");
	if (!tree_symbols) {
		pr_err("no symbols in root of device tree.\n");
		err = -EINVAL;
		goto out;
	}

	for_each_property_of_node(overlay_fixups, prop) {

		/* skip properties added automatically */
		if (!of_prop_cmp(prop->name, "name"))
			continue;

		err = of_property_read_string(tree_symbols,
				prop->name, &refpath);
		if (err) {
			pr_err("node label '%s' not found in live devicetree symbols table\n",
			       prop->name);
			goto out;
		}

		refnode = of_find_node_by_path(refpath);
		if (!refnode) {
			err = -ENOENT;
			goto out;
		}

		phandle = refnode->phandle;
		of_node_put(refnode);

		err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
		if (err)
			break;
	}

out:
	if (err)
		pr_err("overlay phandle fixup failed: %d\n", err);
	of_node_put(tree_symbols);

	return err;
}
EXPORT_SYMBOL_GPL(of_resolve_phandles);