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