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/slab.h> 22 23 #include "of_private.h" 24 25 /* illegal phandle value (set when unresolved) */ 26 #define OF_PHANDLE_ILLEGAL 0xdeadbeef 27 28 static phandle live_tree_max_phandle(void) 29 { 30 struct device_node *node; 31 phandle phandle; 32 unsigned long flags; 33 34 raw_spin_lock_irqsave(&devtree_lock, flags); 35 phandle = 0; 36 for_each_of_allnodes(node) { 37 if (node->phandle != OF_PHANDLE_ILLEGAL && 38 node->phandle > phandle) 39 phandle = node->phandle; 40 } 41 raw_spin_unlock_irqrestore(&devtree_lock, flags); 42 43 return phandle; 44 } 45 46 static void adjust_overlay_phandles(struct device_node *overlay, 47 int phandle_delta) 48 { 49 struct device_node *child; 50 struct property *prop; 51 phandle phandle; 52 53 /* adjust node's phandle in node */ 54 if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL) 55 overlay->phandle += phandle_delta; 56 57 /* copy adjusted phandle into *phandle properties */ 58 for_each_property_of_node(overlay, prop) { 59 60 if (of_prop_cmp(prop->name, "phandle") && 61 of_prop_cmp(prop->name, "linux,phandle")) 62 continue; 63 64 if (prop->length < 4) 65 continue; 66 67 phandle = be32_to_cpup(prop->value); 68 if (phandle == OF_PHANDLE_ILLEGAL) 69 continue; 70 71 *(__be32 *)prop->value = cpu_to_be32(overlay->phandle); 72 } 73 74 for_each_child_of_node(overlay, child) 75 adjust_overlay_phandles(child, phandle_delta); 76 } 77 78 static int update_usages_of_a_phandle_reference(struct device_node *overlay, 79 struct property *prop_fixup, phandle phandle) 80 { 81 struct device_node *refnode; 82 struct property *prop; 83 char *value, *cur, *end, *node_path, *prop_name, *s; 84 int offset, len; 85 int err = 0; 86 87 value = kmemdup(prop_fixup->value, prop_fixup->length, GFP_KERNEL); 88 if (!value) 89 return -ENOMEM; 90 91 /* prop_fixup contains a list of tuples of path:property_name:offset */ 92 end = value + prop_fixup->length; 93 for (cur = value; cur < end; cur += len + 1) { 94 len = strlen(cur); 95 96 node_path = cur; 97 s = strchr(cur, ':'); 98 if (!s) { 99 err = -EINVAL; 100 goto err_fail; 101 } 102 *s++ = '\0'; 103 104 prop_name = s; 105 s = strchr(s, ':'); 106 if (!s) { 107 err = -EINVAL; 108 goto err_fail; 109 } 110 *s++ = '\0'; 111 112 err = kstrtoint(s, 10, &offset); 113 if (err) 114 goto err_fail; 115 116 refnode = __of_find_node_by_full_path(of_node_get(overlay), node_path); 117 if (!refnode) 118 continue; 119 120 for_each_property_of_node(refnode, prop) { 121 if (!of_prop_cmp(prop->name, prop_name)) 122 break; 123 } 124 of_node_put(refnode); 125 126 if (!prop) { 127 err = -ENOENT; 128 goto err_fail; 129 } 130 131 *(__be32 *)(prop->value + offset) = cpu_to_be32(phandle); 132 } 133 134 err_fail: 135 kfree(value); 136 return err; 137 } 138 139 /* compare nodes taking into account that 'name' strips out the @ part */ 140 static int node_name_cmp(const struct device_node *dn1, 141 const struct device_node *dn2) 142 { 143 const char *n1 = kbasename(dn1->full_name); 144 const char *n2 = kbasename(dn2->full_name); 145 146 return of_node_cmp(n1, n2); 147 } 148 149 /* 150 * Adjust the local phandle references by the given phandle delta. 151 * 152 * Subtree @local_fixups, which is overlay node __local_fixups__, 153 * mirrors the fragment node structure at the root of the overlay. 154 * 155 * For each property in the fragments that contains a phandle reference, 156 * @local_fixups has a property of the same name that contains a list 157 * of offsets of the phandle reference(s) within the respective property 158 * value(s). The values at these offsets will be fixed up. 159 */ 160 static int adjust_local_phandle_references(struct device_node *local_fixups, 161 struct device_node *overlay, int phandle_delta) 162 { 163 struct device_node *child, *overlay_child; 164 struct property *prop_fix, *prop; 165 int err, i, count; 166 unsigned int off; 167 168 if (!local_fixups) 169 return 0; 170 171 for_each_property_of_node(local_fixups, prop_fix) { 172 173 /* skip properties added automatically */ 174 if (!of_prop_cmp(prop_fix->name, "name") || 175 !of_prop_cmp(prop_fix->name, "phandle") || 176 !of_prop_cmp(prop_fix->name, "linux,phandle")) 177 continue; 178 179 if ((prop_fix->length % 4) != 0 || prop_fix->length == 0) 180 return -EINVAL; 181 count = prop_fix->length / sizeof(__be32); 182 183 for_each_property_of_node(overlay, prop) { 184 if (!of_prop_cmp(prop->name, prop_fix->name)) 185 break; 186 } 187 188 if (!prop) 189 return -EINVAL; 190 191 for (i = 0; i < count; i++) { 192 off = be32_to_cpu(((__be32 *)prop_fix->value)[i]); 193 if ((off + 4) > prop->length) 194 return -EINVAL; 195 196 be32_add_cpu(prop->value + off, phandle_delta); 197 } 198 } 199 200 /* 201 * These nested loops recurse down two subtrees in parallel, where the 202 * node names in the two subtrees match. 203 * 204 * The roots of the subtrees are the overlay's __local_fixups__ node 205 * and the overlay's root node. 206 */ 207 for_each_child_of_node(local_fixups, child) { 208 209 for_each_child_of_node(overlay, overlay_child) 210 if (!node_name_cmp(child, overlay_child)) 211 break; 212 213 if (!overlay_child) 214 return -EINVAL; 215 216 err = adjust_local_phandle_references(child, overlay_child, 217 phandle_delta); 218 if (err) 219 return err; 220 } 221 222 return 0; 223 } 224 225 /** 226 * of_resolve_phandles - Relocate and resolve overlay against live tree 227 * 228 * @overlay: Pointer to devicetree overlay to relocate and resolve 229 * 230 * Modify (relocate) values of local phandles in @overlay to a range that 231 * does not conflict with the live expanded devicetree. Update references 232 * to the local phandles in @overlay. Update (resolve) phandle references 233 * in @overlay that refer to the live expanded devicetree. 234 * 235 * Phandle values in the live tree are in the range of 236 * 1 .. live_tree_max_phandle(). The range of phandle values in the overlay 237 * also begin with at 1. Adjust the phandle values in the overlay to begin 238 * at live_tree_max_phandle() + 1. Update references to the phandles to 239 * the adjusted phandle values. 240 * 241 * The name of each property in the "__fixups__" node in the overlay matches 242 * the name of a symbol (a label) in the live tree. The values of each 243 * property in the "__fixups__" node is a list of the property values in the 244 * overlay that need to be updated to contain the phandle reference 245 * corresponding to that symbol in the live tree. Update the references in 246 * the overlay with the phandle values in the live tree. 247 * 248 * @overlay must be detached. 249 * 250 * Resolving and applying @overlay to the live expanded devicetree must be 251 * protected by a mechanism to ensure that multiple overlays are processed 252 * in a single threaded manner so that multiple overlays will not relocate 253 * phandles to overlapping ranges. The mechanism to enforce this is not 254 * yet implemented. 255 * 256 * Return: %0 on success or a negative error value on error. 257 */ 258 int of_resolve_phandles(struct device_node *overlay) 259 { 260 struct device_node *child, *local_fixups, *refnode; 261 struct device_node *tree_symbols, *overlay_fixups; 262 struct property *prop; 263 const char *refpath; 264 phandle phandle, phandle_delta; 265 int err; 266 267 tree_symbols = NULL; 268 269 if (!overlay) { 270 pr_err("null overlay\n"); 271 err = -EINVAL; 272 goto out; 273 } 274 if (!of_node_check_flag(overlay, OF_DETACHED)) { 275 pr_err("overlay not detached\n"); 276 err = -EINVAL; 277 goto out; 278 } 279 280 phandle_delta = live_tree_max_phandle() + 1; 281 adjust_overlay_phandles(overlay, phandle_delta); 282 283 for_each_child_of_node(overlay, local_fixups) 284 if (!of_node_cmp(local_fixups->name, "__local_fixups__")) 285 break; 286 287 err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta); 288 if (err) 289 goto out; 290 291 overlay_fixups = NULL; 292 293 for_each_child_of_node(overlay, child) { 294 if (!of_node_cmp(child->name, "__fixups__")) 295 overlay_fixups = child; 296 } 297 298 if (!overlay_fixups) { 299 err = 0; 300 goto out; 301 } 302 303 tree_symbols = of_find_node_by_path("/__symbols__"); 304 if (!tree_symbols) { 305 pr_err("no symbols in root of device tree.\n"); 306 err = -EINVAL; 307 goto out; 308 } 309 310 for_each_property_of_node(overlay_fixups, prop) { 311 312 /* skip properties added automatically */ 313 if (!of_prop_cmp(prop->name, "name")) 314 continue; 315 316 err = of_property_read_string(tree_symbols, 317 prop->name, &refpath); 318 if (err) 319 goto out; 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 } 334 335 out: 336 if (err) 337 pr_err("overlay phandle fixup failed: %d\n", err); 338 of_node_put(tree_symbols); 339 340 return err; 341 } 342 EXPORT_SYMBOL_GPL(of_resolve_phandles); 343