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#define pr_fmt(fmt)	"OF: resolver: " fmt
 13
 14#include <linux/kernel.h>
 15#include <linux/module.h>
 16#include <linux/of.h>
 17#include <linux/of_device.h>
 18#include <linux/string.h>
 19#include <linux/ctype.h>
 20#include <linux/errno.h>
 21#include <linux/string.h>
 22#include <linux/slab.h>
 23
 24/* illegal phandle value (set when unresolved) */
 25#define OF_PHANDLE_ILLEGAL	0xdeadbeef
 26
 27/**
 28 * Find a node with the give full name by recursively following any of
 29 * the child node links.
 30 */
 31static struct device_node *find_node_by_full_name(struct device_node *node,
 32		const char *full_name)
 33{
 34	struct device_node *child, *found;
 35
 36	if (!node)
 37		return NULL;
 38
 39	if (!of_node_cmp(node->full_name, full_name))
 40		return of_node_get(node);
 41
 42	for_each_child_of_node(node, child) {
 43		found = find_node_by_full_name(child, full_name);
 44		if (found != NULL) {
 45			of_node_put(child);
 46			return found;
 47		}
 48	}
 49
 50	return NULL;
 51}
 52
 53static phandle live_tree_max_phandle(void)
 54{
 55	struct device_node *node;
 56	phandle phandle;
 57	unsigned long flags;
 58
 59	raw_spin_lock_irqsave(&devtree_lock, flags);
 60	phandle = 0;
 61	for_each_of_allnodes(node) {
 62		if (node->phandle != OF_PHANDLE_ILLEGAL &&
 63				node->phandle > phandle)
 64			phandle = node->phandle;
 65	}
 66	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 67
 68	return phandle;
 69}
 70
 71static void adjust_overlay_phandles(struct device_node *overlay,
 72		int phandle_delta)
 73{
 74	struct device_node *child;
 75	struct property *prop;
 76	phandle phandle;
 77
 78	/* adjust node's phandle in node */
 79	if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL)
 80		overlay->phandle += phandle_delta;
 81
 82	/* copy adjusted phandle into *phandle properties */
 83	for_each_property_of_node(overlay, prop) {
 84
 85		if (of_prop_cmp(prop->name, "phandle") &&
 86		    of_prop_cmp(prop->name, "linux,phandle"))
 87			continue;
 88
 89		if (prop->length < 4)
 90			continue;
 91
 92		phandle = be32_to_cpup(prop->value);
 93		if (phandle == OF_PHANDLE_ILLEGAL)
 94			continue;
 95
 96		*(uint32_t *)prop->value = cpu_to_be32(overlay->phandle);
 97	}
 98
 99	for_each_child_of_node(overlay, child)
100		adjust_overlay_phandles(child, phandle_delta);
101}
102
103static int update_usages_of_a_phandle_reference(struct device_node *overlay,
104		struct property *prop_fixup, phandle phandle)
105{
106	struct device_node *refnode;
107	struct property *prop;
108	char *value, *cur, *end, *node_path, *prop_name, *s;
109	int offset, len;
110	int err = 0;
111
112	value = kmalloc(prop_fixup->length, GFP_KERNEL);
113	if (!value)
114		return -ENOMEM;
115	memcpy(value, prop_fixup->value, prop_fixup->length);
116
117	/* prop_fixup contains a list of tuples of path:property_name:offset */
118	end = value + prop_fixup->length;
119	for (cur = value; cur < end; cur += len + 1) {
120		len = strlen(cur);
121
122		node_path = cur;
123		s = strchr(cur, ':');
124		if (!s) {
125			err = -EINVAL;
126			goto err_fail;
127		}
128		*s++ = '\0';
129
130		prop_name = s;
131		s = strchr(s, ':');
132		if (!s) {
133			err = -EINVAL;
134			goto err_fail;
135		}
136		*s++ = '\0';
137
138		err = kstrtoint(s, 10, &offset);
139		if (err)
140			goto err_fail;
141
142		refnode = find_node_by_full_name(overlay, node_path);
143		if (!refnode)
144			continue;
145
146		for_each_property_of_node(refnode, prop) {
147			if (!of_prop_cmp(prop->name, prop_name))
148				break;
149		}
150		of_node_put(refnode);
151
152		if (!prop) {
153			err = -ENOENT;
154			goto err_fail;
155		}
156
157		*(__be32 *)(prop->value + offset) = cpu_to_be32(phandle);
158	}
159
160err_fail:
161	kfree(value);
162	return err;
163}
164
165/* compare nodes taking into account that 'name' strips out the @ part */
166static int node_name_cmp(const struct device_node *dn1,
167		const struct device_node *dn2)
168{
169	const char *n1 = strrchr(dn1->full_name, '/') ? : "/";
170	const char *n2 = strrchr(dn2->full_name, '/') ? : "/";
171
172	return of_node_cmp(n1, n2);
173}
174
175/*
176 * Adjust the local phandle references by the given phandle delta.
177 *
178 * Subtree @local_fixups, which is overlay node __local_fixups__,
179 * mirrors the fragment node structure at the root of the overlay.
180 *
181 * For each property in the fragments that contains a phandle reference,
182 * @local_fixups has a property of the same name that contains a list
183 * of offsets of the phandle reference(s) within the respective property
184 * value(s).  The values at these offsets will be fixed up.
185 */
186static int adjust_local_phandle_references(struct device_node *local_fixups,
187		struct device_node *overlay, int phandle_delta)
188{
189	struct device_node *child, *overlay_child;
190	struct property *prop_fix, *prop;
191	int err, i, count;
192	unsigned int off;
193	phandle phandle;
194
195	if (!local_fixups)
196		return 0;
197
198	for_each_property_of_node(local_fixups, prop_fix) {
199
200		/* skip properties added automatically */
201		if (!of_prop_cmp(prop_fix->name, "name") ||
202		    !of_prop_cmp(prop_fix->name, "phandle") ||
203		    !of_prop_cmp(prop_fix->name, "linux,phandle"))
204			continue;
205
206		if ((prop_fix->length % 4) != 0 || prop_fix->length == 0)
207			return -EINVAL;
208		count = prop_fix->length / sizeof(__be32);
209
210		for_each_property_of_node(overlay, prop) {
211			if (!of_prop_cmp(prop->name, prop_fix->name))
212				break;
213		}
214
215		if (!prop)
216			return -EINVAL;
217
218		for (i = 0; i < count; i++) {
219			off = be32_to_cpu(((__be32 *)prop_fix->value)[i]);
220			if ((off + 4) > prop->length)
221				return -EINVAL;
222
223			phandle = be32_to_cpu(*(__be32 *)(prop->value + off));
224			phandle += phandle_delta;
225			*(__be32 *)(prop->value + off) = cpu_to_be32(phandle);
226		}
227	}
228
229	/*
230	 * These nested loops recurse down two subtrees in parallel, where the
231	 * node names in the two subtrees match.
232	 *
233	 * The roots of the subtrees are the overlay's __local_fixups__ node
234	 * and the overlay's root node.
235	 */
236	for_each_child_of_node(local_fixups, child) {
237
238		for_each_child_of_node(overlay, overlay_child)
239			if (!node_name_cmp(child, overlay_child))
240				break;
241
242		if (!overlay_child)
243			return -EINVAL;
244
245		err = adjust_local_phandle_references(child, overlay_child,
246				phandle_delta);
247		if (err)
248			return err;
249	}
250
251	return 0;
252}
253
254/**
255 * of_resolve_phandles - Relocate and resolve overlay against live tree
256 *
257 * @overlay:	Pointer to devicetree overlay to relocate and resolve
258 *
259 * Modify (relocate) values of local phandles in @overlay to a range that
260 * does not conflict with the live expanded devicetree.  Update references
261 * to the local phandles in @overlay.  Update (resolve) phandle references
262 * in @overlay that refer to the live expanded devicetree.
263 *
264 * Phandle values in the live tree are in the range of
265 * 1 .. live_tree_max_phandle().  The range of phandle values in the overlay
266 * also begin with at 1.  Adjust the phandle values in the overlay to begin
267 * at live_tree_max_phandle() + 1.  Update references to the phandles to
268 * the adjusted phandle values.
269 *
270 * The name of each property in the "__fixups__" node in the overlay matches
271 * the name of a symbol (a label) in the live tree.  The values of each
272 * property in the "__fixups__" node is a list of the property values in the
273 * overlay that need to be updated to contain the phandle reference
274 * corresponding to that symbol in the live tree.  Update the references in
275 * the overlay with the phandle values in the live tree.
276 *
277 * @overlay must be detached.
278 *
279 * Resolving and applying @overlay to the live expanded devicetree must be
280 * protected by a mechanism to ensure that multiple overlays are processed
281 * in a single threaded manner so that multiple overlays will not relocate
282 * phandles to overlapping ranges.  The mechanism to enforce this is not
283 * yet implemented.
284 *
285 * Return: %0 on success or a negative error value on error.
286 */
287int of_resolve_phandles(struct device_node *overlay)
288{
289	struct device_node *child, *local_fixups, *refnode;
290	struct device_node *tree_symbols, *overlay_fixups;
291	struct property *prop;
292	const char *refpath;
293	phandle phandle, phandle_delta;
294	int err;
295
296	tree_symbols = NULL;
297
298	if (!overlay) {
299		pr_err("null overlay\n");
300		err = -EINVAL;
301		goto out;
302	}
303	if (!of_node_check_flag(overlay, OF_DETACHED)) {
304		pr_err("overlay not detached\n");
305		err = -EINVAL;
306		goto out;
307	}
308
309	phandle_delta = live_tree_max_phandle() + 1;
310	adjust_overlay_phandles(overlay, phandle_delta);
311
312	for_each_child_of_node(overlay, local_fixups)
313		if (!of_node_cmp(local_fixups->name, "__local_fixups__"))
314			break;
315
316	err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta);
317	if (err)
318		goto out;
319
320	overlay_fixups = NULL;
321
322	for_each_child_of_node(overlay, child) {
323		if (!of_node_cmp(child->name, "__fixups__"))
324			overlay_fixups = child;
325	}
326
327	if (!overlay_fixups) {
328		err = 0;
329		goto out;
330	}
331
332	tree_symbols = of_find_node_by_path("/__symbols__");
333	if (!tree_symbols) {
334		pr_err("no symbols in root of device tree.\n");
335		err = -EINVAL;
336		goto out;
337	}
338
339	for_each_property_of_node(overlay_fixups, prop) {
340
341		/* skip properties added automatically */
342		if (!of_prop_cmp(prop->name, "name"))
343			continue;
344
345		err = of_property_read_string(tree_symbols,
346				prop->name, &refpath);
347		if (err)
348			goto out;
349
350		refnode = of_find_node_by_path(refpath);
351		if (!refnode) {
352			err = -ENOENT;
353			goto out;
354		}
355
356		phandle = refnode->phandle;
357		of_node_put(refnode);
358
359		err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
360		if (err)
361			break;
362	}
363
364out:
365	if (err)
366		pr_err("overlay phandle fixup failed: %d\n", err);
367	of_node_put(tree_symbols);
368
369	return err;
370}
371EXPORT_SYMBOL_GPL(of_resolve_phandles);