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 *(__be32 *)(prop->value + offset) = cpu_to_be32(phandle); 126 } 127 128 err_fail: 129 kfree(value); 130 return err; 131 } 132 133 /* compare nodes taking into account that 'name' strips out the @ part */ 134 static int node_name_cmp(const struct device_node *dn1, 135 const struct device_node *dn2) 136 { 137 const char *n1 = kbasename(dn1->full_name); 138 const char *n2 = kbasename(dn2->full_name); 139 140 return of_node_cmp(n1, n2); 141 } 142 143 /* 144 * Adjust the local phandle references by the given phandle delta. 145 * 146 * Subtree @local_fixups, which is overlay node __local_fixups__, 147 * mirrors the fragment node structure at the root of the overlay. 148 * 149 * For each property in the fragments that contains a phandle reference, 150 * @local_fixups has a property of the same name that contains a list 151 * of offsets of the phandle reference(s) within the respective property 152 * value(s). The values at these offsets will be fixed up. 153 */ 154 static int adjust_local_phandle_references(struct device_node *local_fixups, 155 struct device_node *overlay, int phandle_delta) 156 { 157 struct device_node *child, *overlay_child; 158 struct property *prop_fix, *prop; 159 int err, i, count; 160 unsigned int off; 161 162 if (!local_fixups) 163 return 0; 164 165 for_each_property_of_node(local_fixups, prop_fix) { 166 167 /* skip properties added automatically */ 168 if (!of_prop_cmp(prop_fix->name, "name") || 169 !of_prop_cmp(prop_fix->name, "phandle") || 170 !of_prop_cmp(prop_fix->name, "linux,phandle")) 171 continue; 172 173 if ((prop_fix->length % 4) != 0 || prop_fix->length == 0) 174 return -EINVAL; 175 count = prop_fix->length / sizeof(__be32); 176 177 for_each_property_of_node(overlay, prop) { 178 if (!of_prop_cmp(prop->name, prop_fix->name)) 179 break; 180 } 181 182 if (!prop) 183 return -EINVAL; 184 185 for (i = 0; i < count; i++) { 186 off = be32_to_cpu(((__be32 *)prop_fix->value)[i]); 187 if ((off + 4) > prop->length) 188 return -EINVAL; 189 190 be32_add_cpu(prop->value + off, phandle_delta); 191 } 192 } 193 194 /* 195 * These nested loops recurse down two subtrees in parallel, where the 196 * node names in the two subtrees match. 197 * 198 * The roots of the subtrees are the overlay's __local_fixups__ node 199 * and the overlay's root node. 200 */ 201 for_each_child_of_node(local_fixups, child) { 202 203 for_each_child_of_node(overlay, overlay_child) 204 if (!node_name_cmp(child, overlay_child)) 205 break; 206 207 if (!overlay_child) 208 return -EINVAL; 209 210 err = adjust_local_phandle_references(child, overlay_child, 211 phandle_delta); 212 if (err) 213 return err; 214 } 215 216 return 0; 217 } 218 219 /** 220 * of_resolve_phandles - Relocate and resolve overlay against live tree 221 * 222 * @overlay: Pointer to devicetree overlay to relocate and resolve 223 * 224 * Modify (relocate) values of local phandles in @overlay to a range that 225 * does not conflict with the live expanded devicetree. Update references 226 * to the local phandles in @overlay. Update (resolve) phandle references 227 * in @overlay that refer to the live expanded devicetree. 228 * 229 * Phandle values in the live tree are in the range of 230 * 1 .. live_tree_max_phandle(). The range of phandle values in the overlay 231 * also begin with at 1. Adjust the phandle values in the overlay to begin 232 * at live_tree_max_phandle() + 1. Update references to the phandles to 233 * the adjusted phandle values. 234 * 235 * The name of each property in the "__fixups__" node in the overlay matches 236 * the name of a symbol (a label) in the live tree. The values of each 237 * property in the "__fixups__" node is a list of the property values in the 238 * overlay that need to be updated to contain the phandle reference 239 * corresponding to that symbol in the live tree. Update the references in 240 * the overlay with the phandle values in the live tree. 241 * 242 * @overlay must be detached. 243 * 244 * Resolving and applying @overlay to the live expanded devicetree must be 245 * protected by a mechanism to ensure that multiple overlays are processed 246 * in a single threaded manner so that multiple overlays will not relocate 247 * phandles to overlapping ranges. The mechanism to enforce this is not 248 * yet implemented. 249 * 250 * Return: %0 on success or a negative error value on error. 251 */ 252 int of_resolve_phandles(struct device_node *overlay) 253 { 254 struct device_node *child, *local_fixups, *refnode; 255 struct device_node *tree_symbols, *overlay_fixups; 256 struct property *prop; 257 const char *refpath; 258 phandle phandle, phandle_delta; 259 int err; 260 261 tree_symbols = NULL; 262 263 if (!overlay) { 264 pr_err("null overlay\n"); 265 err = -EINVAL; 266 goto out; 267 } 268 269 if (!of_node_check_flag(overlay, OF_DETACHED)) { 270 pr_err("overlay not detached\n"); 271 err = -EINVAL; 272 goto out; 273 } 274 275 phandle_delta = live_tree_max_phandle() + 1; 276 adjust_overlay_phandles(overlay, phandle_delta); 277 278 for_each_child_of_node(overlay, local_fixups) 279 if (!of_node_cmp(local_fixups->name, "__local_fixups__")) 280 break; 281 282 err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta); 283 if (err) 284 goto out; 285 286 overlay_fixups = NULL; 287 288 for_each_child_of_node(overlay, child) { 289 if (!of_node_cmp(child->name, "__fixups__")) 290 overlay_fixups = child; 291 } 292 293 if (!overlay_fixups) { 294 err = 0; 295 goto out; 296 } 297 298 tree_symbols = of_find_node_by_path("/__symbols__"); 299 if (!tree_symbols) { 300 pr_err("no symbols in root of device tree.\n"); 301 err = -EINVAL; 302 goto out; 303 } 304 305 for_each_property_of_node(overlay_fixups, prop) { 306 307 /* skip properties added automatically */ 308 if (!of_prop_cmp(prop->name, "name")) 309 continue; 310 311 err = of_property_read_string(tree_symbols, 312 prop->name, &refpath); 313 if (err) 314 goto out; 315 316 refnode = of_find_node_by_path(refpath); 317 if (!refnode) { 318 err = -ENOENT; 319 goto out; 320 } 321 322 phandle = refnode->phandle; 323 of_node_put(refnode); 324 325 err = update_usages_of_a_phandle_reference(overlay, prop, phandle); 326 if (err) 327 break; 328 } 329 330 out: 331 if (err) 332 pr_err("overlay phandle fixup failed: %d\n", err); 333 of_node_put(tree_symbols); 334 335 return err; 336 } 337 EXPORT_SYMBOL_GPL(of_resolve_phandles); 338