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