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 */ 31 static 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 53 static 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 71 static 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 } 102 103 static 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 } 159 160 err_fail: 161 kfree(value); 162 return err; 163 } 164 165 /* compare nodes taking into account that 'name' strips out the @ part */ 166 static 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 */ 186 static 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 */ 287 int 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 } 363 364 out: 365 if (err) 366 pr_err("overlay phandle fixup failed: %d\n", err); 367 of_node_put(tree_symbols); 368 369 return err; 370 } 371 EXPORT_SYMBOL_GPL(of_resolve_phandles); 372