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 static phandle live_tree_max_phandle(void) 23 { 24 struct device_node *node; 25 phandle phandle; 26 unsigned long flags; 27 28 raw_spin_lock_irqsave(&devtree_lock, flags); 29 phandle = 0; 30 for_each_of_allnodes(node) { 31 if (node->phandle != OF_PHANDLE_ILLEGAL && 32 node->phandle > phandle) 33 phandle = node->phandle; 34 } 35 raw_spin_unlock_irqrestore(&devtree_lock, flags); 36 37 return phandle; 38 } 39 40 static void adjust_overlay_phandles(struct device_node *overlay, 41 int phandle_delta) 42 { 43 struct device_node *child; 44 struct property *prop; 45 phandle phandle; 46 47 /* adjust node's phandle in node */ 48 if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL) 49 overlay->phandle += phandle_delta; 50 51 /* copy adjusted phandle into *phandle properties */ 52 for_each_property_of_node(overlay, prop) { 53 54 if (of_prop_cmp(prop->name, "phandle") && 55 of_prop_cmp(prop->name, "linux,phandle")) 56 continue; 57 58 if (prop->length < 4) 59 continue; 60 61 phandle = be32_to_cpup(prop->value); 62 if (phandle == OF_PHANDLE_ILLEGAL) 63 continue; 64 65 *(__be32 *)prop->value = cpu_to_be32(overlay->phandle); 66 } 67 68 for_each_child_of_node(overlay, child) 69 adjust_overlay_phandles(child, phandle_delta); 70 } 71 72 static int update_usages_of_a_phandle_reference(struct device_node *overlay, 73 struct property *prop_fixup, phandle phandle) 74 { 75 struct device_node *refnode; 76 struct property *prop; 77 char *value, *cur, *end, *node_path, *prop_name, *s; 78 int offset, len; 79 int err = 0; 80 81 value = kmemdup(prop_fixup->value, prop_fixup->length, GFP_KERNEL); 82 if (!value) 83 return -ENOMEM; 84 85 /* prop_fixup contains a list of tuples of path:property_name:offset */ 86 end = value + prop_fixup->length; 87 for (cur = value; cur < end; cur += len + 1) { 88 len = strlen(cur); 89 90 node_path = cur; 91 s = strchr(cur, ':'); 92 if (!s) { 93 err = -EINVAL; 94 goto err_fail; 95 } 96 *s++ = '\0'; 97 98 prop_name = s; 99 s = strchr(s, ':'); 100 if (!s) { 101 err = -EINVAL; 102 goto err_fail; 103 } 104 *s++ = '\0'; 105 106 err = kstrtoint(s, 10, &offset); 107 if (err) 108 goto err_fail; 109 110 refnode = __of_find_node_by_full_path(of_node_get(overlay), node_path); 111 if (!refnode) 112 continue; 113 114 for_each_property_of_node(refnode, prop) { 115 if (!of_prop_cmp(prop->name, prop_name)) 116 break; 117 } 118 of_node_put(refnode); 119 120 if (!prop) { 121 err = -ENOENT; 122 goto err_fail; 123 } 124 125 if (offset < 0 || offset + sizeof(__be32) > prop->length) { 126 err = -EINVAL; 127 goto err_fail; 128 } 129 130 *(__be32 *)(prop->value + offset) = cpu_to_be32(phandle); 131 } 132 133 err_fail: 134 kfree(value); 135 return err; 136 } 137 138 /* compare nodes taking into account that 'name' strips out the @ part */ 139 static int node_name_cmp(const struct device_node *dn1, 140 const struct device_node *dn2) 141 { 142 const char *n1 = kbasename(dn1->full_name); 143 const char *n2 = kbasename(dn2->full_name); 144 145 return of_node_cmp(n1, n2); 146 } 147 148 /* 149 * Adjust the local phandle references by the given phandle delta. 150 * 151 * Subtree @local_fixups, which is overlay node __local_fixups__, 152 * mirrors the fragment node structure at the root of the overlay. 153 * 154 * For each property in the fragments that contains a phandle reference, 155 * @local_fixups has a property of the same name that contains a list 156 * of offsets of the phandle reference(s) within the respective property 157 * value(s). The values at these offsets will be fixed up. 158 */ 159 static int adjust_local_phandle_references(struct device_node *local_fixups, 160 struct device_node *overlay, int phandle_delta) 161 { 162 struct device_node *child, *overlay_child; 163 struct property *prop_fix, *prop; 164 int err, i, count; 165 unsigned int off; 166 167 if (!local_fixups) 168 return 0; 169 170 for_each_property_of_node(local_fixups, prop_fix) { 171 172 /* skip properties added automatically */ 173 if (!of_prop_cmp(prop_fix->name, "name") || 174 !of_prop_cmp(prop_fix->name, "phandle") || 175 !of_prop_cmp(prop_fix->name, "linux,phandle")) 176 continue; 177 178 if ((prop_fix->length % 4) != 0 || prop_fix->length == 0) 179 return -EINVAL; 180 count = prop_fix->length / sizeof(__be32); 181 182 for_each_property_of_node(overlay, prop) { 183 if (!of_prop_cmp(prop->name, prop_fix->name)) 184 break; 185 } 186 187 if (!prop) 188 return -EINVAL; 189 190 for (i = 0; i < count; i++) { 191 off = be32_to_cpu(((__be32 *)prop_fix->value)[i]); 192 if ((off + 4) > prop->length) 193 return -EINVAL; 194 195 be32_add_cpu(prop->value + off, phandle_delta); 196 } 197 } 198 199 /* 200 * These nested loops recurse down two subtrees in parallel, where the 201 * node names in the two subtrees match. 202 * 203 * The roots of the subtrees are the overlay's __local_fixups__ node 204 * and the overlay's root node. 205 */ 206 for_each_child_of_node(local_fixups, child) { 207 208 for_each_child_of_node(overlay, overlay_child) 209 if (!node_name_cmp(child, overlay_child)) { 210 of_node_put(overlay_child); 211 break; 212 } 213 214 if (!overlay_child) { 215 of_node_put(child); 216 return -EINVAL; 217 } 218 219 err = adjust_local_phandle_references(child, overlay_child, 220 phandle_delta); 221 if (err) { 222 of_node_put(child); 223 return err; 224 } 225 } 226 227 return 0; 228 } 229 230 /** 231 * of_resolve_phandles - Relocate and resolve overlay against live tree 232 * 233 * @overlay: Pointer to devicetree overlay to relocate and resolve 234 * 235 * Modify (relocate) values of local phandles in @overlay to a range that 236 * does not conflict with the live expanded devicetree. Update references 237 * to the local phandles in @overlay. Update (resolve) phandle references 238 * in @overlay that refer to the live expanded devicetree. 239 * 240 * Phandle values in the live tree are in the range of 241 * 1 .. live_tree_max_phandle(). The range of phandle values in the overlay 242 * also begin with at 1. Adjust the phandle values in the overlay to begin 243 * at live_tree_max_phandle() + 1. Update references to the phandles to 244 * the adjusted phandle values. 245 * 246 * The name of each property in the "__fixups__" node in the overlay matches 247 * the name of a symbol (a label) in the live tree. The values of each 248 * property in the "__fixups__" node is a list of the property values in the 249 * overlay that need to be updated to contain the phandle reference 250 * corresponding to that symbol in the live tree. Update the references in 251 * the overlay with the phandle values in the live tree. 252 * 253 * @overlay must be detached. 254 * 255 * Resolving and applying @overlay to the live expanded devicetree must be 256 * protected by a mechanism to ensure that multiple overlays are processed 257 * in a single threaded manner so that multiple overlays will not relocate 258 * phandles to overlapping ranges. The mechanism to enforce this is not 259 * yet implemented. 260 * 261 * Return: %0 on success or a negative error value on error. 262 */ 263 int of_resolve_phandles(struct device_node *overlay) 264 { 265 struct device_node *child, *local_fixups, *refnode; 266 struct device_node *tree_symbols, *overlay_fixups; 267 struct property *prop; 268 const char *refpath; 269 phandle phandle, phandle_delta; 270 int err; 271 272 tree_symbols = NULL; 273 274 if (!overlay) { 275 pr_err("null overlay\n"); 276 err = -EINVAL; 277 goto out; 278 } 279 280 if (!of_node_check_flag(overlay, OF_DETACHED)) { 281 pr_err("overlay not detached\n"); 282 err = -EINVAL; 283 goto out; 284 } 285 286 phandle_delta = live_tree_max_phandle() + 1; 287 adjust_overlay_phandles(overlay, phandle_delta); 288 289 for_each_child_of_node(overlay, local_fixups) 290 if (of_node_name_eq(local_fixups, "__local_fixups__")) 291 break; 292 293 err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta); 294 if (err) 295 goto out; 296 297 overlay_fixups = NULL; 298 299 for_each_child_of_node(overlay, child) { 300 if (of_node_name_eq(child, "__fixups__")) 301 overlay_fixups = child; 302 } 303 304 if (!overlay_fixups) { 305 err = 0; 306 goto out; 307 } 308 309 tree_symbols = of_find_node_by_path("/__symbols__"); 310 if (!tree_symbols) { 311 pr_err("no symbols in root of device tree.\n"); 312 err = -EINVAL; 313 goto out; 314 } 315 316 for_each_property_of_node(overlay_fixups, prop) { 317 318 /* skip properties added automatically */ 319 if (!of_prop_cmp(prop->name, "name")) 320 continue; 321 322 err = of_property_read_string(tree_symbols, 323 prop->name, &refpath); 324 if (err) 325 goto out; 326 327 refnode = of_find_node_by_path(refpath); 328 if (!refnode) { 329 err = -ENOENT; 330 goto out; 331 } 332 333 phandle = refnode->phandle; 334 of_node_put(refnode); 335 336 err = update_usages_of_a_phandle_reference(overlay, prop, phandle); 337 if (err) 338 break; 339 } 340 341 out: 342 if (err) 343 pr_err("overlay phandle fixup failed: %d\n", err); 344 of_node_put(tree_symbols); 345 346 return err; 347 } 348 EXPORT_SYMBOL_GPL(of_resolve_phandles); 349