1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Functions for dealing with DT resolution 4 * 5 * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com> 6 * Copyright (C) 2012 Texas Instruments Inc. 7 */ 8 9 #define pr_fmt(fmt) "OF: resolver: " fmt 10 11 #include <linux/kernel.h> 12 #include <linux/module.h> 13 #include <linux/of.h> 14 #include <linux/of_device.h> 15 #include <linux/string.h> 16 #include <linux/ctype.h> 17 #include <linux/errno.h> 18 #include <linux/slab.h> 19 20 #include "of_private.h" 21 22 /* illegal phandle value (set when unresolved) */ 23 #define OF_PHANDLE_ILLEGAL 0xdeadbeef 24 25 static phandle live_tree_max_phandle(void) 26 { 27 struct device_node *node; 28 phandle phandle; 29 unsigned long flags; 30 31 raw_spin_lock_irqsave(&devtree_lock, flags); 32 phandle = 0; 33 for_each_of_allnodes(node) { 34 if (node->phandle != OF_PHANDLE_ILLEGAL && 35 node->phandle > phandle) 36 phandle = node->phandle; 37 } 38 raw_spin_unlock_irqrestore(&devtree_lock, flags); 39 40 return phandle; 41 } 42 43 static void adjust_overlay_phandles(struct device_node *overlay, 44 int phandle_delta) 45 { 46 struct device_node *child; 47 struct property *prop; 48 phandle phandle; 49 50 /* adjust node's phandle in node */ 51 if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL) 52 overlay->phandle += phandle_delta; 53 54 /* copy adjusted phandle into *phandle properties */ 55 for_each_property_of_node(overlay, prop) { 56 57 if (of_prop_cmp(prop->name, "phandle") && 58 of_prop_cmp(prop->name, "linux,phandle")) 59 continue; 60 61 if (prop->length < 4) 62 continue; 63 64 phandle = be32_to_cpup(prop->value); 65 if (phandle == OF_PHANDLE_ILLEGAL) 66 continue; 67 68 *(__be32 *)prop->value = cpu_to_be32(overlay->phandle); 69 } 70 71 for_each_child_of_node(overlay, child) 72 adjust_overlay_phandles(child, phandle_delta); 73 } 74 75 static int update_usages_of_a_phandle_reference(struct device_node *overlay, 76 struct property *prop_fixup, phandle phandle) 77 { 78 struct device_node *refnode; 79 struct property *prop; 80 char *value, *cur, *end, *node_path, *prop_name, *s; 81 int offset, len; 82 int err = 0; 83 84 value = kmemdup(prop_fixup->value, prop_fixup->length, GFP_KERNEL); 85 if (!value) 86 return -ENOMEM; 87 88 /* prop_fixup contains a list of tuples of path:property_name:offset */ 89 end = value + prop_fixup->length; 90 for (cur = value; cur < end; cur += len + 1) { 91 len = strlen(cur); 92 93 node_path = cur; 94 s = strchr(cur, ':'); 95 if (!s) { 96 err = -EINVAL; 97 goto err_fail; 98 } 99 *s++ = '\0'; 100 101 prop_name = s; 102 s = strchr(s, ':'); 103 if (!s) { 104 err = -EINVAL; 105 goto err_fail; 106 } 107 *s++ = '\0'; 108 109 err = kstrtoint(s, 10, &offset); 110 if (err) 111 goto err_fail; 112 113 refnode = __of_find_node_by_full_path(of_node_get(overlay), node_path); 114 if (!refnode) 115 continue; 116 117 for_each_property_of_node(refnode, prop) { 118 if (!of_prop_cmp(prop->name, prop_name)) 119 break; 120 } 121 of_node_put(refnode); 122 123 if (!prop) { 124 err = -ENOENT; 125 goto err_fail; 126 } 127 128 *(__be32 *)(prop->value + offset) = cpu_to_be32(phandle); 129 } 130 131 err_fail: 132 kfree(value); 133 return err; 134 } 135 136 /* compare nodes taking into account that 'name' strips out the @ part */ 137 static int node_name_cmp(const struct device_node *dn1, 138 const struct device_node *dn2) 139 { 140 const char *n1 = kbasename(dn1->full_name); 141 const char *n2 = kbasename(dn2->full_name); 142 143 return of_node_cmp(n1, n2); 144 } 145 146 /* 147 * Adjust the local phandle references by the given phandle delta. 148 * 149 * Subtree @local_fixups, which is overlay node __local_fixups__, 150 * mirrors the fragment node structure at the root of the overlay. 151 * 152 * For each property in the fragments that contains a phandle reference, 153 * @local_fixups has a property of the same name that contains a list 154 * of offsets of the phandle reference(s) within the respective property 155 * value(s). The values at these offsets will be fixed up. 156 */ 157 static int adjust_local_phandle_references(struct device_node *local_fixups, 158 struct device_node *overlay, int phandle_delta) 159 { 160 struct device_node *child, *overlay_child; 161 struct property *prop_fix, *prop; 162 int err, i, count; 163 unsigned int off; 164 165 if (!local_fixups) 166 return 0; 167 168 for_each_property_of_node(local_fixups, prop_fix) { 169 170 /* skip properties added automatically */ 171 if (!of_prop_cmp(prop_fix->name, "name") || 172 !of_prop_cmp(prop_fix->name, "phandle") || 173 !of_prop_cmp(prop_fix->name, "linux,phandle")) 174 continue; 175 176 if ((prop_fix->length % 4) != 0 || prop_fix->length == 0) 177 return -EINVAL; 178 count = prop_fix->length / sizeof(__be32); 179 180 for_each_property_of_node(overlay, prop) { 181 if (!of_prop_cmp(prop->name, prop_fix->name)) 182 break; 183 } 184 185 if (!prop) 186 return -EINVAL; 187 188 for (i = 0; i < count; i++) { 189 off = be32_to_cpu(((__be32 *)prop_fix->value)[i]); 190 if ((off + 4) > prop->length) 191 return -EINVAL; 192 193 be32_add_cpu(prop->value + off, phandle_delta); 194 } 195 } 196 197 /* 198 * These nested loops recurse down two subtrees in parallel, where the 199 * node names in the two subtrees match. 200 * 201 * The roots of the subtrees are the overlay's __local_fixups__ node 202 * and the overlay's root node. 203 */ 204 for_each_child_of_node(local_fixups, child) { 205 206 for_each_child_of_node(overlay, overlay_child) 207 if (!node_name_cmp(child, overlay_child)) 208 break; 209 210 if (!overlay_child) 211 return -EINVAL; 212 213 err = adjust_local_phandle_references(child, overlay_child, 214 phandle_delta); 215 if (err) 216 return err; 217 } 218 219 return 0; 220 } 221 222 /** 223 * of_resolve_phandles - Relocate and resolve overlay against live tree 224 * 225 * @overlay: Pointer to devicetree overlay to relocate and resolve 226 * 227 * Modify (relocate) values of local phandles in @overlay to a range that 228 * does not conflict with the live expanded devicetree. Update references 229 * to the local phandles in @overlay. Update (resolve) phandle references 230 * in @overlay that refer to the live expanded devicetree. 231 * 232 * Phandle values in the live tree are in the range of 233 * 1 .. live_tree_max_phandle(). The range of phandle values in the overlay 234 * also begin with at 1. Adjust the phandle values in the overlay to begin 235 * at live_tree_max_phandle() + 1. Update references to the phandles to 236 * the adjusted phandle values. 237 * 238 * The name of each property in the "__fixups__" node in the overlay matches 239 * the name of a symbol (a label) in the live tree. The values of each 240 * property in the "__fixups__" node is a list of the property values in the 241 * overlay that need to be updated to contain the phandle reference 242 * corresponding to that symbol in the live tree. Update the references in 243 * the overlay with the phandle values in the live tree. 244 * 245 * @overlay must be detached. 246 * 247 * Resolving and applying @overlay to the live expanded devicetree must be 248 * protected by a mechanism to ensure that multiple overlays are processed 249 * in a single threaded manner so that multiple overlays will not relocate 250 * phandles to overlapping ranges. The mechanism to enforce this is not 251 * yet implemented. 252 * 253 * Return: %0 on success or a negative error value on error. 254 */ 255 int of_resolve_phandles(struct device_node *overlay) 256 { 257 struct device_node *child, *local_fixups, *refnode; 258 struct device_node *tree_symbols, *overlay_fixups; 259 struct property *prop; 260 const char *refpath; 261 phandle phandle, phandle_delta; 262 int err; 263 264 tree_symbols = NULL; 265 266 if (!overlay) { 267 pr_err("null overlay\n"); 268 err = -EINVAL; 269 goto out; 270 } 271 272 #if 0 273 Temporarily disable check so that old style overlay unittests 274 do not fail when of_resolve_phandles() is moved into 275 of_overlay_apply(). 276 277 if (!of_node_check_flag(overlay, OF_DETACHED)) { 278 pr_err("overlay not detached\n"); 279 err = -EINVAL; 280 goto out; 281 } 282 #endif 283 284 phandle_delta = live_tree_max_phandle() + 1; 285 adjust_overlay_phandles(overlay, phandle_delta); 286 287 for_each_child_of_node(overlay, local_fixups) 288 if (!of_node_cmp(local_fixups->name, "__local_fixups__")) 289 break; 290 291 err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta); 292 if (err) 293 goto out; 294 295 overlay_fixups = NULL; 296 297 for_each_child_of_node(overlay, child) { 298 if (!of_node_cmp(child->name, "__fixups__")) 299 overlay_fixups = child; 300 } 301 302 if (!overlay_fixups) { 303 err = 0; 304 goto out; 305 } 306 307 tree_symbols = of_find_node_by_path("/__symbols__"); 308 if (!tree_symbols) { 309 pr_err("no symbols in root of device tree.\n"); 310 err = -EINVAL; 311 goto out; 312 } 313 314 for_each_property_of_node(overlay_fixups, prop) { 315 316 /* skip properties added automatically */ 317 if (!of_prop_cmp(prop->name, "name")) 318 continue; 319 320 err = of_property_read_string(tree_symbols, 321 prop->name, &refpath); 322 if (err) 323 goto out; 324 325 refnode = of_find_node_by_path(refpath); 326 if (!refnode) { 327 err = -ENOENT; 328 goto out; 329 } 330 331 phandle = refnode->phandle; 332 of_node_put(refnode); 333 334 err = update_usages_of_a_phandle_reference(overlay, prop, phandle); 335 if (err) 336 break; 337 } 338 339 out: 340 if (err) 341 pr_err("overlay phandle fixup failed: %d\n", err); 342 of_node_put(tree_symbols); 343 344 return err; 345 } 346 EXPORT_SYMBOL_GPL(of_resolve_phandles); 347