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