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 const 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 const struct property *prop_fixup, phandle phandle) 75 { 76 struct device_node *refnode; 77 const 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(const struct device_node *local_fixups, 151 const struct device_node *overlay, int phandle_delta) 152 { 153 struct device_node *overlay_child; 154 const 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 (is_pseudo_property(prop_fix->name)) 165 continue; 166 167 if ((prop_fix->length % 4) != 0 || prop_fix->length == 0) 168 return -EINVAL; 169 count = prop_fix->length / sizeof(__be32); 170 171 for_each_property_of_node(overlay, prop) { 172 if (!of_prop_cmp(prop->name, prop_fix->name)) 173 break; 174 } 175 176 if (!prop) 177 return -EINVAL; 178 179 for (i = 0; i < count; i++) { 180 off = be32_to_cpu(((__be32 *)prop_fix->value)[i]); 181 if ((off + 4) > prop->length) 182 return -EINVAL; 183 184 be32_add_cpu(prop->value + off, phandle_delta); 185 } 186 } 187 188 /* 189 * These nested loops recurse down two subtrees in parallel, where the 190 * node names in the two subtrees match. 191 * 192 * The roots of the subtrees are the overlay's __local_fixups__ node 193 * and the overlay's root node. 194 */ 195 for_each_child_of_node_scoped(local_fixups, child) { 196 197 for_each_child_of_node(overlay, overlay_child) 198 if (!node_name_cmp(child, overlay_child)) { 199 of_node_put(overlay_child); 200 break; 201 } 202 203 if (!overlay_child) 204 return -EINVAL; 205 206 err = adjust_local_phandle_references(child, overlay_child, 207 phandle_delta); 208 if (err) 209 return err; 210 } 211 212 return 0; 213 } 214 215 /** 216 * of_resolve_phandles - Relocate and resolve overlay against live tree 217 * 218 * @overlay: Pointer to devicetree overlay to relocate and resolve 219 * 220 * Modify (relocate) values of local phandles in @overlay to a range that 221 * does not conflict with the live expanded devicetree. Update references 222 * to the local phandles in @overlay. Update (resolve) phandle references 223 * in @overlay that refer to the live expanded devicetree. 224 * 225 * Phandle values in the live tree are in the range of 226 * 1 .. live_tree_max_phandle(). The range of phandle values in the overlay 227 * also begin with at 1. Adjust the phandle values in the overlay to begin 228 * at live_tree_max_phandle() + 1. Update references to the phandles to 229 * the adjusted phandle values. 230 * 231 * The name of each property in the "__fixups__" node in the overlay matches 232 * the name of a symbol (a label) in the live tree. The values of each 233 * property in the "__fixups__" node is a list of the property values in the 234 * overlay that need to be updated to contain the phandle reference 235 * corresponding to that symbol in the live tree. Update the references in 236 * the overlay with the phandle values in the live tree. 237 * 238 * @overlay must be detached. 239 * 240 * Resolving and applying @overlay to the live expanded devicetree must be 241 * protected by a mechanism to ensure that multiple overlays are processed 242 * in a single threaded manner so that multiple overlays will not relocate 243 * phandles to overlapping ranges. The mechanism to enforce this is not 244 * yet implemented. 245 * 246 * Return: %0 on success or a negative error value on error. 247 */ 248 int of_resolve_phandles(struct device_node *overlay) 249 { 250 struct device_node *child, *refnode; 251 struct device_node *overlay_fixups; 252 struct device_node __free(device_node) *local_fixups = NULL; 253 struct property *prop; 254 const char *refpath; 255 phandle phandle, phandle_delta; 256 int err; 257 258 if (!overlay) { 259 pr_err("null overlay\n"); 260 return -EINVAL; 261 } 262 263 if (!of_node_check_flag(overlay, OF_DETACHED)) { 264 pr_err("overlay not detached\n"); 265 return -EINVAL; 266 } 267 268 phandle_delta = live_tree_max_phandle() + 1; 269 adjust_overlay_phandles(overlay, phandle_delta); 270 271 for_each_child_of_node(overlay, local_fixups) 272 if (of_node_name_eq(local_fixups, "__local_fixups__")) 273 break; 274 275 err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta); 276 if (err) 277 return err; 278 279 overlay_fixups = NULL; 280 281 for_each_child_of_node(overlay, child) { 282 if (of_node_name_eq(child, "__fixups__")) 283 overlay_fixups = child; 284 } 285 286 if (!overlay_fixups) 287 return 0; 288 289 struct device_node __free(device_node) *tree_symbols = of_find_node_by_path("/__symbols__"); 290 if (!tree_symbols) { 291 pr_err("no symbols in root of device tree.\n"); 292 return -EINVAL; 293 } 294 295 for_each_property_of_node(overlay_fixups, prop) { 296 297 /* skip properties added automatically */ 298 if (!of_prop_cmp(prop->name, "name")) 299 continue; 300 301 err = of_property_read_string(tree_symbols, 302 prop->name, &refpath); 303 if (err) { 304 pr_err("node label '%s' not found in live devicetree symbols table\n", 305 prop->name); 306 return err; 307 } 308 309 refnode = of_find_node_by_path(refpath); 310 if (!refnode) 311 return -ENOENT; 312 313 phandle = refnode->phandle; 314 of_node_put(refnode); 315 316 err = update_usages_of_a_phandle_reference(overlay, prop, phandle); 317 if (err) 318 break; 319 } 320 321 if (err) 322 pr_err("overlay phandle fixup failed: %d\n", err); 323 return err; 324 } 325 EXPORT_SYMBOL_GPL(of_resolve_phandles); 326