/* Taken from depthcharge: src/base/device_tree.c */ /* SPDX-License-Identifier: GPL-2.0-or-later */ #include #include #include #include #include #include #include #include #include #include #define FDT_PATH_MAX_DEPTH 10 // should be a good enough upper bound #define FDT_PATH_MAX_LEN 128 // should be a good enough upper bound /* * Functions for picking apart flattened trees. */ static int fdt_skip_nops(const void *blob, uint32_t offset) { uint32_t *ptr = (uint32_t *)(((uint8_t *)blob) + offset); int index = 0; while (be32toh(ptr[index]) == FDT_TOKEN_NOP) index++; return index * sizeof(uint32_t); } int fdt_next_property(const void *blob, uint32_t offset, struct fdt_property *prop) { struct fdt_header *header = (struct fdt_header *)blob; uint32_t *ptr = (uint32_t *)(((uint8_t *)blob) + offset); // skip NOP tokens offset += fdt_skip_nops(blob, offset); int index = 0; if (be32toh(ptr[index++]) != FDT_TOKEN_PROPERTY) return 0; uint32_t size = be32toh(ptr[index++]); uint32_t name_offset = be32toh(ptr[index++]); name_offset += be32toh(header->strings_offset); if (prop) { prop->name = (char *)((uint8_t *)blob + name_offset); prop->data = &ptr[index]; prop->size = size; } index += DIV_ROUND_UP(size, sizeof(uint32_t)); return index * sizeof(uint32_t); } /* * fdt_next_node_name reads a node name * * @params blob address of FDT * @params offset offset to the node to read the name from * @params name parameter to hold the name that has been read or NULL * * @returns Either 0 on error or offset to the properties that come after the node name */ int fdt_next_node_name(const void *blob, uint32_t offset, const char **name) { // skip NOP tokens offset += fdt_skip_nops(blob, offset); char *ptr = ((char *)blob) + offset; if (be32dec(ptr) != FDT_TOKEN_BEGIN_NODE) return 0; ptr += 4; if (name) *name = ptr; return ALIGN_UP(strlen(ptr) + 1, 4) + 4; } /* * A utility function to skip past nodes in flattened trees. */ int fdt_skip_node(const void *blob, uint32_t start_offset) { uint32_t offset = start_offset; const char *name; int size = fdt_next_node_name(blob, offset, &name); if (!size) return 0; offset += size; while ((size = fdt_next_property(blob, offset, NULL))) offset += size; while ((size = fdt_skip_node(blob, offset))) offset += size; // skip NOP tokens offset += fdt_skip_nops(blob, offset); return offset - start_offset + sizeof(uint32_t); } /* * fdt_read_prop reads a property inside a node * * @params blob address of FDT * @params node_offset offset to the node to read the property from * @params prop_name name of the property to read * @params fdt_prop property is saved inside this parameter * * @returns Either 0 if no property has been found or an offset that points to the location * of the property */ u32 fdt_read_prop(const void *blob, u32 node_offset, const char *prop_name, struct fdt_property *fdt_prop) { u32 offset = node_offset; offset += fdt_next_node_name(blob, offset, NULL); // skip node name size_t size; while ((size = fdt_next_property(blob, offset, fdt_prop))) { if (strcmp(fdt_prop->name, prop_name) == 0) return offset; offset += size; } return 0; // property not found } /* * fdt_read_reg_prop reads the reg property inside a node * * @params blob address of FDT * @params node_offset offset to the node to read the reg property from * @params addr_cells number of cells used for one address * @params size_cells number of cells used for one size * @params regions all regions that are read inside the reg property are saved inside * this array * @params regions_count maximum number of entries that can be saved inside the regions array. * * Returns: Either 0 on error or returns the number of regions put into the regions array. */ u32 fdt_read_reg_prop(const void *blob, u32 node_offset, u32 addr_cells, u32 size_cells, struct device_tree_region regions[], size_t regions_count) { struct fdt_property prop; u32 offset = fdt_read_prop(blob, node_offset, "reg", &prop); if (!offset) { printk(BIOS_DEBUG, "no reg property found in node_offset: %x\n", node_offset); return 0; } // we found the reg property, now need to parse all regions in 'reg' size_t count = prop.size / (4 * addr_cells + 4 * size_cells); if (count > regions_count) { printk(BIOS_ERR, "reg property at node_offset: %x has more entries (%zd) than regions array can hold (%zd)\n", node_offset, count, regions_count); count = regions_count; } if (addr_cells > 2 || size_cells > 2) { printk(BIOS_ERR, "addr_cells (%d) or size_cells (%d) bigger than 2\n", addr_cells, size_cells); return 0; } uint32_t *ptr = prop.data; for (int i = 0; i < count; i++) { if (addr_cells == 1) regions[i].addr = be32dec(ptr); else if (addr_cells == 2) regions[i].addr = be64dec(ptr); ptr += addr_cells; if (size_cells == 1) regions[i].size = be32dec(ptr); else if (size_cells == 2) regions[i].size = be64dec(ptr); ptr += size_cells; } return count; // return the number of regions found in the reg property } static u32 fdt_read_cell_props(const void *blob, u32 node_offset, u32 *addrcp, u32 *sizecp) { struct fdt_property prop; u32 offset = node_offset; size_t size; while ((size = fdt_next_property(blob, offset, &prop))) { if (addrcp && !strcmp(prop.name, "#address-cells")) *addrcp = be32dec(prop.data); if (sizecp && !strcmp(prop.name, "#size-cells")) *sizecp = be32dec(prop.data); offset += size; } return offset; } /* * fdt_find_node searches for a node relative to another node * * @params blob address of FDT * * @params parent_node_offset offset to node from which to traverse the tree * * @params path null terminated array of node names specifying a * relative path (e.g: { "cpus", "cpu0", NULL }) * * @params addrcp/sizecp If any address-cells and size-cells properties are found that are * part of the parent node of the node we are looking, addrcp and sizecp * are set to these respectively. * * @returns: Either 0 if no node has been found or the offset to the node found */ static u32 fdt_find_node(const void *blob, u32 parent_node_offset, char **path, u32 *addrcp, u32 *sizecp) { if (*path == NULL) return parent_node_offset; // node found size_t size = fdt_next_node_name(blob, parent_node_offset, NULL); // skip node name /* * get address-cells and size-cells properties while skipping the others. * According to spec address-cells and size-cells are not inherited, but we * intentionally follow the Linux implementation here and treat them as inheritable. */ u32 node_offset = fdt_read_cell_props(blob, parent_node_offset + size, addrcp, sizecp); const char *node_name; // walk all children nodes while ((size = fdt_next_node_name(blob, node_offset, &node_name))) { if (!strcmp(*path, node_name)) { // traverse one level deeper into the path return fdt_find_node(blob, node_offset, path + 1, addrcp, sizecp); } // node is not the correct one. skip current node node_offset += fdt_skip_node(blob, node_offset); } // we have searched everything and could not find a fitting node return 0; } /* * fdt_find_node_by_path finds a node behind a given node path * * @params blob address of FDT * @params path absolute path to the node that should be searched for * * @params addrcp/sizecp Pointer that will be updated with any #address-cells and #size-cells * value found in the node of the node specified by node_offset. Either * may be NULL to ignore. If no #address-cells and #size-cells is found * default values of #address-cells=2 and #size-cells=1 are returned. * * @returns Either 0 on error or the offset to the node found behind the path */ u32 fdt_find_node_by_path(const void *blob, const char *path, u32 *addrcp, u32 *sizecp) { // sanity check if (path[0] != '/') { printk(BIOS_ERR, "devicetree path must start with a /\n"); return 0; } if (!blob) { printk(BIOS_ERR, "devicetree blob is NULL\n"); return 0; } if (addrcp) *addrcp = 2; if (sizecp) *sizecp = 1; struct fdt_header *fdt_hdr = (struct fdt_header *)blob; /* * split path into separate nodes * e.g: "/cpus/cpu0" -> { "cpus", "cpu0" } */ char *path_array[FDT_PATH_MAX_DEPTH]; size_t path_size = strlen(path); assert(path_size < FDT_PATH_MAX_LEN); char path_copy[FDT_PATH_MAX_LEN]; memcpy(path_copy, path, path_size + 1); char *cur = path_copy; int i; for (i = 0; i < FDT_PATH_MAX_DEPTH; i++) { path_array[i] = strtok_r(NULL, "/", &cur); if (!path_array[i]) break; } assert(i < FDT_PATH_MAX_DEPTH); return fdt_find_node(blob, be32toh(fdt_hdr->structure_offset), path_array, addrcp, sizecp); } /* * fdt_find_subnodes_by_prefix finds a node with a given prefix relative to a parent node * * @params blob The FDT to search. * * @params node_offset offset to the node of which the children should be searched * * @params prefix A string to search for a node with a given prefix. This can for example * be 'cpu' to look for all nodes matching this prefix. Only children of * node_offset are searched. Therefore in order to search all nodes matching * the 'cpu' prefix, node_offset should probably point to the 'cpus' node. * An empty prefix ("") searches for all children nodes of node_offset. * * @params addrcp/sizecp Pointer that will be updated with any #address-cells and #size-cells * value found in the node of the node specified by node_offset. Either * may be NULL to ignore. If no #address-cells and #size-cells is found * addrcp and sizecp are left untouched. * * @params results Array of offsets pointing to each node matching the given prefix. * @params results_len Number of entries allocated for the 'results' array * * @returns offset to last node found behind path or 0 if no node has been found */ size_t fdt_find_subnodes_by_prefix(const void *blob, u32 node_offset, const char *prefix, u32 *addrcp, u32 *sizecp, u32 *results, size_t results_len) { // sanity checks if (!blob || !results || !prefix) { printk(BIOS_ERR, "%s: input parameter cannot be null/\n", __func__); return 0; } u32 offset = node_offset; // we don't care about the name of the current node u32 size = fdt_next_node_name(blob, offset, NULL); if (!size) { printk(BIOS_ERR, "%s: node_offset: %x does not point to a node\n", __func__, node_offset); return 0; } offset += size; /* * update addrcp and sizecp if the node contains an address-cells and size-cells * property. Otherwise use addrcp and sizecp provided by caller. */ offset = fdt_read_cell_props(blob, offset, addrcp, sizecp); size_t count_results = 0; int prefix_len = strlen(prefix); const char *node_name; // walk all children nodes of offset while ((size = fdt_next_node_name(blob, offset, &node_name))) { if (count_results >= results_len) { printk(BIOS_WARNING, "%s: results_len (%zd) smaller than count_results (%zd)\n", __func__, results_len, count_results); break; } if (!strncmp(prefix, node_name, prefix_len)) { // we found a node that matches the prefix results[count_results++] = offset; } // node does not match the prefix. skip current node offset += fdt_skip_node(blob, offset); } // return last occurrence return count_results; } static const char *fdt_read_alias_prop(const void *blob, const char *alias_name) { u32 node_offset = fdt_find_node_by_path(blob, "/aliases", NULL, NULL); if (!node_offset) { printk(BIOS_DEBUG, "no /aliases node found\n"); return NULL; } struct fdt_property alias_prop; if (!fdt_read_prop(blob, node_offset, alias_name, &alias_prop)) { printk(BIOS_DEBUG, "property %s in /aliases node not found\n", alias_name); return NULL; } return (const char *)alias_prop.data; } /* * Find a node in the tree from a string device tree path. * * @params blob Address to the FDT * @params alias_name node name alias that should be searched for. * @params addrcp/sizecp Pointer that will be updated with any #address-cells and #size-cells * value found in the node of the node specified by node_offset. Either * may be NULL to ignore. If no #address-cells and #size-cells is found * default values of #address-cells=2 and #size-cells=1 are returned. * * @returns offset to last node found behind path or 0 if no node has been found */ u32 fdt_find_node_by_alias(const void *blob, const char *alias_name, u32 *addrcp, u32 *sizecp) { const char *node_name = fdt_read_alias_prop(blob, alias_name); if (!node_name) { printk(BIOS_DEBUG, "alias %s not found\n", alias_name); return 0; } u32 node_offset = fdt_find_node_by_path(blob, node_name, addrcp, sizecp); if (!node_offset) { // This should not happen (invalid devicetree) printk(BIOS_WARNING, "Could not find node '%s', which alias was referring to '%s'\n", node_name, alias_name); return 0; } return node_offset; } /* * Functions for printing flattened trees. */ static void print_indent(int depth) { printk(BIOS_DEBUG, "%*s", depth * 8, ""); } static void print_property(const struct fdt_property *prop, int depth) { int is_string = prop->size > 0 && ((char *)prop->data)[prop->size - 1] == '\0'; if (is_string) { for (int i = 0; i < prop->size - 1; i++) { if (!isprint(((char *)prop->data)[i])) { is_string = 0; break; } } } print_indent(depth); if (is_string) { printk(BIOS_DEBUG, "%s = \"%s\";\n", prop->name, (const char *)prop->data); } else { printk(BIOS_DEBUG, "%s = < ", prop->name); for (int i = 0; i < MIN(128, prop->size); i += 4) { uint32_t val = 0; for (int j = 0; j < MIN(4, prop->size - i); j++) val |= ((uint8_t *)prop->data)[i + j] << (24 - j * 8); printk(BIOS_DEBUG, "%#.2x ", val); } if (prop->size > 128) printk(BIOS_DEBUG, "..."); printk(BIOS_DEBUG, ">;\n"); } } static int print_flat_node(const void *blob, uint32_t start_offset, int depth) { int offset = start_offset; const char *name; int size; size = fdt_next_node_name(blob, offset, &name); if (!size) return 0; offset += size; print_indent(depth); printk(BIOS_DEBUG, "%s {\n", name); struct fdt_property prop; while ((size = fdt_next_property(blob, offset, &prop))) { print_property(&prop, depth + 1); offset += size; } printk(BIOS_DEBUG, "\n"); /* empty line between props and nodes */ while ((size = print_flat_node(blob, offset, depth + 1))) offset += size; print_indent(depth); printk(BIOS_DEBUG, "}\n"); return offset - start_offset + sizeof(uint32_t); } void fdt_print_node(const void *blob, uint32_t offset) { print_flat_node(blob, offset, 0); } /* * Functions to turn a flattened tree into an unflattened one. */ static int dt_prop_is_phandle(struct device_tree_property *prop) { return !(strcmp("phandle", prop->prop.name) && strcmp("linux,phandle", prop->prop.name)); } static int fdt_unflatten_node(const void *blob, uint32_t start_offset, struct device_tree *tree, struct device_tree_node **new_node) { struct list_node *last; int offset = start_offset; const char *name; int size; size = fdt_next_node_name(blob, offset, &name); if (!size) return 0; offset += size; struct device_tree_node *node = xzalloc(sizeof(*node)); *new_node = node; node->name = name; struct fdt_property fprop; last = &node->properties; while ((size = fdt_next_property(blob, offset, &fprop))) { struct device_tree_property *prop = xzalloc(sizeof(*prop)); prop->prop = fprop; if (dt_prop_is_phandle(prop)) { node->phandle = be32dec(prop->prop.data); if (node->phandle > tree->max_phandle) tree->max_phandle = node->phandle; } list_insert_after(&prop->list_node, last); last = &prop->list_node; offset += size; } struct device_tree_node *child; last = &node->children; while ((size = fdt_unflatten_node(blob, offset, tree, &child))) { list_insert_after(&child->list_node, last); last = &child->list_node; offset += size; } return offset - start_offset + sizeof(uint32_t); } static int fdt_unflatten_map_entry(const void *blob, uint32_t offset, struct device_tree_reserve_map_entry **new) { const uint64_t *ptr = (const uint64_t *)(((uint8_t *)blob) + offset); const uint64_t start = be64toh(ptr[0]); const uint64_t size = be64toh(ptr[1]); if (!size) return 0; struct device_tree_reserve_map_entry *entry = xzalloc(sizeof(*entry)); *new = entry; entry->start = start; entry->size = size; return sizeof(uint64_t) * 2; } bool fdt_is_valid(const void *blob) { const struct fdt_header *header = (const struct fdt_header *)blob; uint32_t magic = be32toh(header->magic); uint32_t version = be32toh(header->version); uint32_t last_comp_version = be32toh(header->last_comp_version); if (magic != FDT_HEADER_MAGIC) { printk(BIOS_ERR, "Invalid device tree magic %#.8x!\n", magic); return false; } if (last_comp_version > FDT_SUPPORTED_VERSION) { printk(BIOS_ERR, "Unsupported device tree version %u(>=%u)\n", version, last_comp_version); return false; } if (version > FDT_SUPPORTED_VERSION) printk(BIOS_NOTICE, "FDT version %u too new, should add support!\n", version); return true; } struct device_tree *fdt_unflatten(const void *blob) { struct device_tree *tree = xzalloc(sizeof(*tree)); const struct fdt_header *header = (const struct fdt_header *)blob; tree->header = header; if (fdt_is_valid(blob)) return NULL; uint32_t struct_offset = be32toh(header->structure_offset); uint32_t strings_offset = be32toh(header->strings_offset); uint32_t reserve_offset = be32toh(header->reserve_map_offset); uint32_t min_offset = 0; min_offset = MIN(struct_offset, strings_offset); min_offset = MIN(min_offset, reserve_offset); /* Assume everything up to the first non-header component is part of the header and needs to be preserved. This will protect us against new elements being added in the future. */ tree->header_size = min_offset; struct device_tree_reserve_map_entry *entry; uint32_t offset = reserve_offset; int size; struct list_node *last = &tree->reserve_map; while ((size = fdt_unflatten_map_entry(blob, offset, &entry))) { list_insert_after(&entry->list_node, last); last = &entry->list_node; offset += size; } fdt_unflatten_node(blob, struct_offset, tree, &tree->root); return tree; } /* * Functions to find the size of the device tree if it was flattened. */ static void dt_flat_prop_size(struct device_tree_property *prop, uint32_t *struct_size, uint32_t *strings_size) { /* Starting token. */ *struct_size += sizeof(uint32_t); /* Size. */ *struct_size += sizeof(uint32_t); /* Name offset. */ *struct_size += sizeof(uint32_t); /* Property value. */ *struct_size += ALIGN_UP(prop->prop.size, sizeof(uint32_t)); /* Property name. */ *strings_size += strlen(prop->prop.name) + 1; } static void dt_flat_node_size(struct device_tree_node *node, uint32_t *struct_size, uint32_t *strings_size) { /* Starting token. */ *struct_size += sizeof(uint32_t); /* Node name. */ *struct_size += ALIGN_UP(strlen(node->name) + 1, sizeof(uint32_t)); struct device_tree_property *prop; list_for_each(prop, node->properties, list_node) dt_flat_prop_size(prop, struct_size, strings_size); struct device_tree_node *child; list_for_each(child, node->children, list_node) dt_flat_node_size(child, struct_size, strings_size); /* End token. */ *struct_size += sizeof(uint32_t); } uint32_t dt_flat_size(const struct device_tree *tree) { uint32_t size = tree->header_size; struct device_tree_reserve_map_entry *entry; list_for_each(entry, tree->reserve_map, list_node) size += sizeof(uint64_t) * 2; size += sizeof(uint64_t) * 2; uint32_t struct_size = 0; uint32_t strings_size = 0; dt_flat_node_size(tree->root, &struct_size, &strings_size); size += struct_size; /* End token. */ size += sizeof(uint32_t); size += strings_size; return size; } /* * Functions to flatten a device tree. */ static void dt_flatten_map_entry(struct device_tree_reserve_map_entry *entry, void **map_start) { ((uint64_t *)*map_start)[0] = htobe64(entry->start); ((uint64_t *)*map_start)[1] = htobe64(entry->size); *map_start = ((uint8_t *)*map_start) + sizeof(uint64_t) * 2; } static void dt_flatten_prop(struct device_tree_property *prop, void **struct_start, void *strings_base, void **strings_start) { uint8_t *dstruct = (uint8_t *)*struct_start; uint8_t *dstrings = (uint8_t *)*strings_start; be32enc(dstruct, FDT_TOKEN_PROPERTY); dstruct += sizeof(uint32_t); be32enc(dstruct, prop->prop.size); dstruct += sizeof(uint32_t); uint32_t name_offset = (uintptr_t)dstrings - (uintptr_t)strings_base; be32enc(dstruct, name_offset); dstruct += sizeof(uint32_t); strcpy((char *)dstrings, prop->prop.name); dstrings += strlen(prop->prop.name) + 1; memcpy(dstruct, prop->prop.data, prop->prop.size); dstruct += ALIGN_UP(prop->prop.size, sizeof(uint32_t)); *struct_start = dstruct; *strings_start = dstrings; } static void dt_flatten_node(const struct device_tree_node *node, void **struct_start, void *strings_base, void **strings_start) { uint8_t *dstruct = (uint8_t *)*struct_start; uint8_t *dstrings = (uint8_t *)*strings_start; be32enc(dstruct, FDT_TOKEN_BEGIN_NODE); dstruct += sizeof(uint32_t); strcpy((char *)dstruct, node->name); dstruct += ALIGN_UP(strlen(node->name) + 1, sizeof(uint32_t)); struct device_tree_property *prop; list_for_each(prop, node->properties, list_node) dt_flatten_prop(prop, (void **)&dstruct, strings_base, (void **)&dstrings); struct device_tree_node *child; list_for_each(child, node->children, list_node) dt_flatten_node(child, (void **)&dstruct, strings_base, (void **)&dstrings); be32enc(dstruct, FDT_TOKEN_END_NODE); dstruct += sizeof(uint32_t); *struct_start = dstruct; *strings_start = dstrings; } void dt_flatten(const struct device_tree *tree, void *start_dest) { uint8_t *dest = (uint8_t *)start_dest; memcpy(dest, tree->header, tree->header_size); struct fdt_header *header = (struct fdt_header *)dest; dest += tree->header_size; struct device_tree_reserve_map_entry *entry; list_for_each(entry, tree->reserve_map, list_node) dt_flatten_map_entry(entry, (void **)&dest); ((uint64_t *)dest)[0] = ((uint64_t *)dest)[1] = 0; dest += sizeof(uint64_t) * 2; uint32_t struct_size = 0; uint32_t strings_size = 0; dt_flat_node_size(tree->root, &struct_size, &strings_size); uint8_t *struct_start = dest; header->structure_offset = htobe32(dest - (uint8_t *)start_dest); header->structure_size = htobe32(struct_size); dest += struct_size; *((uint32_t *)dest) = htobe32(FDT_TOKEN_END); dest += sizeof(uint32_t); uint8_t *strings_start = dest; header->strings_offset = htobe32(dest - (uint8_t *)start_dest); header->strings_size = htobe32(strings_size); dest += strings_size; dt_flatten_node(tree->root, (void **)&struct_start, strings_start, (void **)&strings_start); header->totalsize = htobe32(dest - (uint8_t *)start_dest); } /* * Functions for printing a non-flattened device tree. */ static void print_node(const struct device_tree_node *node, int depth) { print_indent(depth); if (depth == 0) /* root node has no name, print a starting slash */ printk(BIOS_DEBUG, "/"); printk(BIOS_DEBUG, "%s {\n", node->name); struct device_tree_property *prop; list_for_each(prop, node->properties, list_node) print_property(&prop->prop, depth + 1); printk(BIOS_DEBUG, "\n"); /* empty line between props and nodes */ struct device_tree_node *child; list_for_each(child, node->children, list_node) print_node(child, depth + 1); print_indent(depth); printk(BIOS_DEBUG, "};\n"); } void dt_print_node(const struct device_tree_node *node) { print_node(node, 0); } /* * Functions for reading and manipulating an unflattened device tree. */ /* * Read #address-cells and #size-cells properties from a node. * * @param node The device tree node to read from. * @param addrcp Pointer to store #address-cells in, skipped if NULL. * @param sizecp Pointer to store #size-cells in, skipped if NULL. */ void dt_read_cell_props(const struct device_tree_node *node, u32 *addrcp, u32 *sizecp) { struct device_tree_property *prop; list_for_each(prop, node->properties, list_node) { if (addrcp && !strcmp("#address-cells", prop->prop.name)) *addrcp = be32dec(prop->prop.data); if (sizecp && !strcmp("#size-cells", prop->prop.name)) *sizecp = be32dec(prop->prop.data); } } /* * Find a node from a device tree path, relative to a parent node. * * @param parent The node from which to start the relative path lookup. * @param path An array of path component strings that will be looked * up in order to find the node. Must be terminated with * a NULL pointer. Example: {'firmware', 'coreboot', NULL} * @param addrcp Pointer that will be updated with any #address-cells * value found in the path. May be NULL to ignore. * @param sizecp Pointer that will be updated with any #size-cells * value found in the path. May be NULL to ignore. * @param create 1: Create node(s) if not found. 0: Return NULL instead. * @return The found/created node, or NULL. */ struct device_tree_node *dt_find_node(struct device_tree_node *parent, const char **path, u32 *addrcp, u32 *sizecp, int create) { struct device_tree_node *node, *found = NULL; /* Update #address-cells and #size-cells for this level. */ dt_read_cell_props(parent, addrcp, sizecp); if (!*path) return parent; /* Find the next node in the path, if it exists. */ list_for_each(node, parent->children, list_node) { if (!strcmp(node->name, *path)) { found = node; break; } } /* Otherwise create it or return NULL. */ if (!found) { if (!create) return NULL; found = calloc(1, sizeof(*found)); if (!found) return NULL; found->name = strdup(*path); if (!found->name) return NULL; list_insert_after(&found->list_node, &parent->children); } return dt_find_node(found, path + 1, addrcp, sizecp, create); } /* * Find a node in the tree from a string device tree path. * * @param tree The device tree to search. * @param path A string representing a path in the device tree, with * nodes separated by '/'. Example: "/firmware/coreboot" * @param addrcp Pointer that will be updated with any #address-cells * value found in the path. May be NULL to ignore. * @param sizecp Pointer that will be updated with any #size-cells * value found in the path. May be NULL to ignore. * @param create 1: Create node(s) if not found. 0: Return NULL instead. * @return The found/created node, or NULL. * * It is the caller responsibility to provide a path string that doesn't end * with a '/' and doesn't contain any "//". If the path does not start with a * '/', the first segment is interpreted as an alias. */ struct device_tree_node *dt_find_node_by_path(struct device_tree *tree, const char *path, u32 *addrcp, u32 *sizecp, int create) { char *sub_path; char *duped_str; struct device_tree_node *parent; char *next_slash; /* Hopefully enough depth for any node. */ const char *path_array[15]; int i; struct device_tree_node *node = NULL; if (path[0] == '/') { /* regular path */ if (path[1] == '\0') { /* special case: "/" is root node */ dt_read_cell_props(tree->root, addrcp, sizecp); return tree->root; } sub_path = duped_str = strdup(&path[1]); if (!sub_path) return NULL; parent = tree->root; } else { /* alias */ char *alias; alias = duped_str = strdup(path); if (!alias) return NULL; sub_path = strchr(alias, '/'); if (sub_path) *sub_path = '\0'; parent = dt_find_node_by_alias(tree, alias); if (!parent) { printk(BIOS_DEBUG, "Could not find node '%s', alias '%s' does not exist\n", path, alias); free(duped_str); return NULL; } if (!sub_path) { /* it's just the alias, no sub-path */ free(duped_str); return parent; } sub_path++; } next_slash = sub_path; path_array[0] = sub_path; for (i = 1; i < (ARRAY_SIZE(path_array) - 1); i++) { next_slash = strchr(next_slash, '/'); if (!next_slash) break; *next_slash++ = '\0'; path_array[i] = next_slash; } if (!next_slash) { path_array[i] = NULL; node = dt_find_node(parent, path_array, addrcp, sizecp, create); } free(duped_str); return node; } /* * Find a node from an alias * * @param tree The device tree. * @param alias The alias name. * @return The found node, or NULL. */ struct device_tree_node *dt_find_node_by_alias(struct device_tree *tree, const char *alias) { struct device_tree_node *node; const char *alias_path; node = dt_find_node_by_path(tree, "/aliases", NULL, NULL, 0); if (!node) return NULL; alias_path = dt_find_string_prop(node, alias); if (!alias_path) return NULL; return dt_find_node_by_path(tree, alias_path, NULL, NULL, 0); } struct device_tree_node *dt_find_node_by_phandle(struct device_tree_node *root, uint32_t phandle) { if (!root) return NULL; if (root->phandle == phandle) return root; struct device_tree_node *node; struct device_tree_node *result; list_for_each(node, root->children, list_node) { result = dt_find_node_by_phandle(node, phandle); if (result) return result; } return NULL; } /* * Check if given node is compatible. * * @param node The node which is to be checked for compatible property. * @param compat The compatible string to match. * @return 1 = compatible, 0 = not compatible. */ static int dt_check_compat_match(struct device_tree_node *node, const char *compat) { struct device_tree_property *prop; list_for_each(prop, node->properties, list_node) { if (!strcmp("compatible", prop->prop.name)) { size_t bytes = prop->prop.size; const char *str = prop->prop.data; while (bytes > 0) { if (!strncmp(compat, str, bytes)) return 1; size_t len = strnlen(str, bytes) + 1; if (bytes <= len) break; str += len; bytes -= len; } break; } } return 0; } /* * Find a node from a compatible string, in the subtree of a parent node. * * @param parent The parent node under which to look. * @param compat The compatible string to find. * @return The found node, or NULL. */ struct device_tree_node *dt_find_compat(struct device_tree_node *parent, const char *compat) { /* Check if the parent node itself is compatible. */ if (dt_check_compat_match(parent, compat)) return parent; struct device_tree_node *child; list_for_each(child, parent->children, list_node) { struct device_tree_node *found = dt_find_compat(child, compat); if (found) return found; } return NULL; } /* * Find the next compatible child of a given parent. All children up to the * child passed in by caller are ignored. If child is NULL, it considers all the * children to find the first child which is compatible. * * @param parent The parent node under which to look. * @param child The child node to start search from (exclusive). If NULL * consider all children. * @param compat The compatible string to find. * @return The found node, or NULL. */ struct device_tree_node * dt_find_next_compat_child(struct device_tree_node *parent, struct device_tree_node *child, const char *compat) { struct device_tree_node *next; int ignore = 0; if (child) ignore = 1; list_for_each(next, parent->children, list_node) { if (ignore) { if (child == next) ignore = 0; continue; } if (dt_check_compat_match(next, compat)) return next; } return NULL; } /* * Find a node with matching property value, in the subtree of a parent node. * * @param parent The parent node under which to look. * @param name The property name to look for. * @param data The property value to look for. * @param size The property size. */ struct device_tree_node *dt_find_prop_value(struct device_tree_node *parent, const char *name, void *data, size_t size) { struct device_tree_property *prop; /* Check if parent itself has the required property value. */ list_for_each(prop, parent->properties, list_node) { if (!strcmp(name, prop->prop.name)) { size_t bytes = prop->prop.size; const void *prop_data = prop->prop.data; if (size != bytes) break; if (!memcmp(data, prop_data, size)) return parent; break; } } struct device_tree_node *child; list_for_each(child, parent->children, list_node) { struct device_tree_node *found = dt_find_prop_value(child, name, data, size); if (found) return found; } return NULL; } /* * Write an arbitrary sized big-endian integer into a pointer. * * @param dest Pointer to the DT property data buffer to write. * @param src The integer to write (in CPU endianness). * @param length the length of the destination integer in bytes. */ void dt_write_int(u8 *dest, u64 src, size_t length) { while (length--) { dest[length] = (u8)src; src >>= 8; } } /* * Delete a property by name in a given node if it exists. * * @param node The device tree node to operate on. * @param name The name of the property to delete. */ void dt_delete_prop(struct device_tree_node *node, const char *name) { struct device_tree_property *prop; list_for_each(prop, node->properties, list_node) { if (!strcmp(prop->prop.name, name)) { list_remove(&prop->list_node); return; } } } /* * Add an arbitrary property to a node, or update it if it already exists. * * @param node The device tree node to add to. * @param name The name of the new property. * @param data The raw data blob to be stored in the property. * @param size The size of data in bytes. */ void dt_add_bin_prop(struct device_tree_node *node, const char *name, void *data, size_t size) { struct device_tree_property *prop; list_for_each(prop, node->properties, list_node) { if (!strcmp(prop->prop.name, name)) { prop->prop.data = data; prop->prop.size = size; return; } } prop = xzalloc(sizeof(*prop)); list_insert_after(&prop->list_node, &node->properties); prop->prop.name = name; prop->prop.data = data; prop->prop.size = size; } /* * Find given string property in a node and return its content. * * @param node The device tree node to search. * @param name The name of the property. * @return The found string, or NULL. */ const char *dt_find_string_prop(const struct device_tree_node *node, const char *name) { const void *content; size_t size; dt_find_bin_prop(node, name, &content, &size); return content; } /* * Find given property in a node. * * @param node The device tree node to search. * @param name The name of the property. * @param data Pointer to return raw data blob in the property. * @param size Pointer to return the size of data in bytes. */ void dt_find_bin_prop(const struct device_tree_node *node, const char *name, const void **data, size_t *size) { struct device_tree_property *prop; *data = NULL; *size = 0; list_for_each(prop, node->properties, list_node) { if (!strcmp(prop->prop.name, name)) { *data = prop->prop.data; *size = prop->prop.size; return; } } } /* * Add a string property to a node, or update it if it already exists. * * @param node The device tree node to add to. * @param name The name of the new property. * @param str The zero-terminated string to be stored in the property. */ void dt_add_string_prop(struct device_tree_node *node, const char *name, const char *str) { dt_add_bin_prop(node, name, (char *)str, strlen(str) + 1); } /* * Add a 32-bit integer property to a node, or update it if it already exists. * * @param node The device tree node to add to. * @param name The name of the new property. * @param val The integer to be stored in the property. */ void dt_add_u32_prop(struct device_tree_node *node, const char *name, u32 val) { u32 *val_ptr = xmalloc(sizeof(val)); *val_ptr = htobe32(val); dt_add_bin_prop(node, name, val_ptr, sizeof(*val_ptr)); } /* * Add a 64-bit integer property to a node, or update it if it already exists. * * @param node The device tree node to add to. * @param name The name of the new property. * @param val The integer to be stored in the property. */ void dt_add_u64_prop(struct device_tree_node *node, const char *name, u64 val) { u64 *val_ptr = xmalloc(sizeof(val)); *val_ptr = htobe64(val); dt_add_bin_prop(node, name, val_ptr, sizeof(*val_ptr)); } /* * Add a 'reg' address list property to a node, or update it if it exists. * * @param node The device tree node to add to. * @param regions Array of address values to be stored in the property. * @param sizes Array of corresponding size values to 'addrs'. * @param count Number of values in 'addrs' and 'sizes' (must be equal). * @param addr_cells Value of #address-cells property valid for this node. * @param size_cells Value of #size-cells property valid for this node. */ void dt_add_reg_prop(struct device_tree_node *node, u64 *addrs, u64 *sizes, int count, u32 addr_cells, u32 size_cells) { int i; size_t length = (addr_cells + size_cells) * sizeof(u32) * count; u8 *data = xmalloc(length); u8 *cur = data; for (i = 0; i < count; i++) { dt_write_int(cur, addrs[i], addr_cells * sizeof(u32)); cur += addr_cells * sizeof(u32); dt_write_int(cur, sizes[i], size_cells * sizeof(u32)); cur += size_cells * sizeof(u32); } dt_add_bin_prop(node, "reg", data, length); } /* * Fixups to apply to a kernel's device tree before booting it. */ struct list_node device_tree_fixups; int dt_apply_fixups(struct device_tree *tree) { struct device_tree_fixup *fixup; list_for_each(fixup, device_tree_fixups, list_node) { assert(fixup->fixup); if (fixup->fixup(fixup, tree)) return 1; } return 0; } int dt_set_bin_prop_by_path(struct device_tree *tree, const char *path, void *data, size_t data_size, int create) { char *path_copy, *prop_name; struct device_tree_node *dt_node; path_copy = strdup(path); if (!path_copy) { printk(BIOS_ERR, "Failed to allocate a copy of path %s\n", path); return 1; } prop_name = strrchr(path_copy, '/'); if (!prop_name) { free(path_copy); printk(BIOS_ERR, "Path %s does not include '/'\n", path); return 1; } *prop_name++ = '\0'; /* Separate path from the property name. */ dt_node = dt_find_node_by_path(tree, path_copy, NULL, NULL, create); if (!dt_node) { printk(BIOS_ERR, "Failed to %s %s in the device tree\n", create ? "create" : "find", path_copy); free(path_copy); return 1; } dt_add_bin_prop(dt_node, prop_name, data, data_size); free(path_copy); return 0; } /* * Prepare the /reserved-memory/ node. * * Technically, this can be called more than one time, to init and/or retrieve * the node. But dt_add_u32_prop() may leak a bit of memory if you do. * * @tree: Device tree to add/retrieve from. * @return: The /reserved-memory/ node (or NULL, if error). */ struct device_tree_node *dt_init_reserved_memory_node(struct device_tree *tree) { struct device_tree_node *reserved; u32 addr = 0, size = 0; reserved = dt_find_node_by_path(tree, "/reserved-memory", &addr, &size, 1); if (!reserved) return NULL; /* Binding doc says this should have the same #{address,size}-cells as the root. */ dt_add_u32_prop(reserved, "#address-cells", addr); dt_add_u32_prop(reserved, "#size-cells", size); /* Binding doc says this should be empty (1:1 mapping from root). */ dt_add_bin_prop(reserved, "ranges", NULL, 0); return reserved; } /* * Increment a single phandle in prop at a given offset by a given adjustment. * * @param prop Property whose phandle should be adjusted. * @param adjustment Value that should be added to the existing phandle. * @param offset Byte offset of the phandle in the property data. * * @return New phandle value, or 0 on error. */ static uint32_t dt_adjust_phandle(struct device_tree_property *prop, uint32_t adjustment, uint32_t offset) { if (offset + 4 > prop->prop.size) return 0; uint32_t phandle = be32dec(prop->prop.data + offset); if (phandle == 0 || phandle == FDT_PHANDLE_ILLEGAL || phandle == 0xffffffff) return 0; phandle += adjustment; if (phandle >= FDT_PHANDLE_ILLEGAL) return 0; be32enc(prop->prop.data + offset, phandle); return phandle; } /* * Adjust all phandles in subtree by adding a new base offset. * * @param node Root node of the subtree to work on. * @param base New phandle base to be added to all phandles. * * @return New highest phandle in the subtree, or 0 on error. */ static uint32_t dt_adjust_all_phandles(struct device_tree_node *node, uint32_t base) { uint32_t new_max = MAX(base, 1); /* make sure we don't return 0 */ struct device_tree_property *prop; struct device_tree_node *child; if (!node) return new_max; list_for_each(prop, node->properties, list_node) if (dt_prop_is_phandle(prop)) { node->phandle = dt_adjust_phandle(prop, base, 0); if (!node->phandle) return 0; new_max = MAX(new_max, node->phandle); } /* no break -- can have more than one phandle prop */ list_for_each(child, node->children, list_node) new_max = MAX(new_max, dt_adjust_all_phandles(child, base)); return new_max; } /* * Apply a /__local_fixup__ subtree to the corresponding overlay subtree. * * @param node Root node of the overlay subtree to fix up. * @param node Root node of the /__local_fixup__ subtree. * @param base Adjustment that was added to phandles in the overlay. * * @return 0 on success, -1 on error. */ static int dt_fixup_locals(struct device_tree_node *node, struct device_tree_node *fixup, uint32_t base) { struct device_tree_property *prop; struct device_tree_property *fixup_prop; struct device_tree_node *child; struct device_tree_node *fixup_child; int i; /* * For local fixups the /__local_fixup__ subtree contains the same node * hierarchy as the main tree we're fixing up. Each property contains * the fixup offsets for the respective property in the main tree. For * each property in the fixup node, find the corresponding property in * the base node and apply fixups to all offsets it specifies. */ list_for_each(fixup_prop, fixup->properties, list_node) { struct device_tree_property *base_prop = NULL; list_for_each(prop, node->properties, list_node) if (!strcmp(prop->prop.name, fixup_prop->prop.name)) { base_prop = prop; break; } /* We should always find a corresponding base prop for a fixup, and fixup props contain a list of 32-bit fixup offsets. */ if (!base_prop || fixup_prop->prop.size % sizeof(uint32_t)) return -1; for (i = 0; i < fixup_prop->prop.size; i += sizeof(uint32_t)) if (!dt_adjust_phandle(base_prop, base, be32dec( fixup_prop->prop.data + i))) return -1; } /* Now recursively descend both the base tree and the /__local_fixups__ subtree in sync to apply all fixups. */ list_for_each(fixup_child, fixup->children, list_node) { struct device_tree_node *base_child = NULL; list_for_each(child, node->children, list_node) if (!strcmp(child->name, fixup_child->name)) { base_child = child; break; } /* All fixup nodes should have a corresponding base node. */ if (!base_child) return -1; if (dt_fixup_locals(base_child, fixup_child, base) < 0) return -1; } return 0; } /* * Update all /__symbols__ properties in an overlay that start with * "/fragment@X/__overlay__" with corresponding path prefix in the base tree. * * @param symbols /__symbols__ done to update. * @param fragment /fragment@X node that references to should be updated. * @param base_path Path of base tree node that the fragment overlaid. */ static void dt_fix_symbols(struct device_tree_node *symbols, struct device_tree_node *fragment, const char *base_path) { struct device_tree_property *prop; char buf[512]; /* Should be enough for maximum DT path length? */ char node_path[64]; /* easily enough for /fragment@XXXX/__overlay__ */ if (!symbols) /* If the overlay has no /__symbols__ node, we're done! */ return; int len = snprintf(node_path, sizeof(node_path), "/%s/__overlay__", fragment->name); list_for_each(prop, symbols->properties, list_node) if (!strncmp(prop->prop.data, node_path, len)) { prop->prop.size = snprintf(buf, sizeof(buf), "%s%s", base_path, (char *)prop->prop.data + len) + 1; free(prop->prop.data); prop->prop.data = strdup(buf); } } /* * Fix up overlay according to a property in /__fixup__. If the fixed property * is a /fragment@X:target, also update /__symbols__ references to fragment. * * @params overlay Overlay to fix up. * @params fixup /__fixup__ property. * @params phandle phandle value to insert where the fixup points to. * @params base_path Path to the base DT node that the fixup points to. * @params overlay_symbols /__symbols__ node of the overlay. * * @return 0 on success, -1 on error. */ static int dt_fixup_external(struct device_tree *overlay, struct device_tree_property *fixup, uint32_t phandle, const char *base_path, struct device_tree_node *overlay_symbols) { struct device_tree_property *prop; /* External fixup properties are encoded as "::". */ char *entry = fixup->prop.data; while ((void *)entry < fixup->prop.data + fixup->prop.size) { /* okay to destroy fixup property value, won't need it again */ char *node_path = entry; entry = strchr(node_path, ':'); if (!entry) return -1; *entry++ = '\0'; char *prop_name = entry; entry = strchr(prop_name, ':'); if (!entry) return -1; *entry++ = '\0'; struct device_tree_node *ovl_node = dt_find_node_by_path( overlay, node_path, NULL, NULL, 0); if (!ovl_node || !isdigit(*entry)) return -1; struct device_tree_property *ovl_prop = NULL; list_for_each(prop, ovl_node->properties, list_node) if (!strcmp(prop->prop.name, prop_name)) { ovl_prop = prop; break; } /* Move entry to first char after number, must be a '\0'. */ uint32_t offset = skip_atoi(&entry); if (!ovl_prop || offset + 4 > ovl_prop->prop.size || entry[0]) return -1; entry++; /* jump over '\0' to potential next fixup */ be32enc(ovl_prop->prop.data + offset, phandle); /* If this is a /fragment@X:target property, update references to this fragment in the overlay __symbols__ now. */ if (offset == 0 && !strcmp(prop_name, "target") && !strchr(node_path + 1, '/')) /* only toplevel nodes */ dt_fix_symbols(overlay_symbols, ovl_node, base_path); } return 0; } /* * Apply all /__fixup__ properties in the overlay. This will destroy the * property data in /__fixup__ and it should not be accessed again. * * @params tree Base device tree that the overlay updates. * @params symbols /__symbols__ node of the base device tree. * @params overlay Overlay to fix up. * @params fixups /__fixup__ node in the overlay. * @params overlay_symbols /__symbols__ node of the overlay. * * @return 0 on success, -1 on error. */ static int dt_fixup_all_externals(struct device_tree *tree, struct device_tree_node *symbols, struct device_tree *overlay, struct device_tree_node *fixups, struct device_tree_node *overlay_symbols) { struct device_tree_property *fix; /* If we have any external fixups, base tree must have /__symbols__. */ if (!symbols) return -1; /* * Unlike /__local_fixups__, /__fixups__ is not a whole subtree that * mirrors the node hierarchy. It's just a directory of fixup properties * that each directly contain all information necessary to apply them. */ list_for_each(fix, fixups->properties, list_node) { /* The name of a fixup property is the label of the node we want a property to phandle-reference. Look up in /__symbols__. */ const char *path = dt_find_string_prop(symbols, fix->prop.name); if (!path) return -1; /* Find node the label pointed to figure out its phandle. */ struct device_tree_node *node = dt_find_node_by_path(tree, path, NULL, NULL, 0); if (!node) return -1; /* Write into the overlay property(s) pointing to that node. */ if (dt_fixup_external(overlay, fix, node->phandle, path, overlay_symbols) < 0) return -1; } return 0; } /* * Copy all nodes and properties from one DT subtree into another. This is a * shallow copy so both trees will point to the same property data afterwards. * * @params dst Destination subtree to copy into. * @params src Source subtree to copy from. * @params upd 1 to overwrite same-name properties, 0 to discard them. */ static void dt_copy_subtree(struct device_tree_node *dst, struct device_tree_node *src, int upd) { struct device_tree_property *prop; struct device_tree_property *src_prop; list_for_each(src_prop, src->properties, list_node) { if (dt_prop_is_phandle(src_prop) || !strcmp(src_prop->prop.name, "name")) { printk(BIOS_DEBUG, "WARNING: ignoring illegal overlay prop '%s'\n", src_prop->prop.name); continue; } struct device_tree_property *dst_prop = NULL; list_for_each(prop, dst->properties, list_node) if (!strcmp(prop->prop.name, src_prop->prop.name)) { dst_prop = prop; break; } if (dst_prop) { if (!upd) { printk(BIOS_DEBUG, "WARNING: ignoring prop update '%s'\n", src_prop->prop.name); continue; } } else { dst_prop = xzalloc(sizeof(*dst_prop)); list_insert_after(&dst_prop->list_node, &dst->properties); } dst_prop->prop = src_prop->prop; } struct device_tree_node *node; struct device_tree_node *src_node; list_for_each(src_node, src->children, list_node) { struct device_tree_node *dst_node = NULL; list_for_each(node, dst->children, list_node) if (!strcmp(node->name, src_node->name)) { dst_node = node; break; } if (!dst_node) { dst_node = xzalloc(sizeof(*dst_node)); *dst_node = *src_node; list_insert_after(&dst_node->list_node, &dst->children); } else { dt_copy_subtree(dst_node, src_node, upd); } } } /* * Apply an overlay /fragment@X node to a base device tree. * * @param tree Base device tree. * @param fragment /fragment@X node. * @params overlay_symbols /__symbols__ node of the overlay. * * @return 0 on success, -1 on error. */ static int dt_import_fragment(struct device_tree *tree, struct device_tree_node *fragment, struct device_tree_node *overlay_symbols) { /* The actual overlaid nodes/props are in an __overlay__ child node. */ static const char *overlay_path[] = { "__overlay__", NULL }; struct device_tree_node *overlay = dt_find_node(fragment, overlay_path, NULL, NULL, 0); /* If it doesn't have an __overlay__ child, it's not a fragment. */ if (!overlay) return 0; /* Target node of the fragment can be given by path or by phandle. */ struct device_tree_property *prop; struct device_tree_property *phandle = NULL; struct device_tree_property *path = NULL; list_for_each(prop, fragment->properties, list_node) { if (!strcmp(prop->prop.name, "target")) { phandle = prop; break; /* phandle target has priority, stop looking */ } if (!strcmp(prop->prop.name, "target-path")) path = prop; } struct device_tree_node *target = NULL; if (phandle) { if (phandle->prop.size != sizeof(uint32_t)) return -1; target = dt_find_node_by_phandle(tree->root, be32dec(phandle->prop.data)); /* Symbols already updated as part of dt_fixup_external(). */ } else if (path) { target = dt_find_node_by_path(tree, path->prop.data, NULL, NULL, 0); dt_fix_symbols(overlay_symbols, fragment, path->prop.data); } if (!target) return -1; dt_copy_subtree(target, overlay, 1); return 0; } /* * Apply a device tree overlay to a base device tree. This will * destroy/incorporate the overlay data, so it should not be freed or reused. * See dtc.git/Documentation/dt-object-internal.txt for overlay format details. * * @param tree Unflattened base device tree to add the overlay into. * @param overlay Unflattened overlay device tree to apply to the base. * * @return 0 on success, -1 on error. */ int dt_apply_overlay(struct device_tree *tree, struct device_tree *overlay) { /* * First, we need to make sure phandles inside the overlay don't clash * with those in the base tree. We just define the highest phandle value * in the base tree as the "phandle offset" for this overlay and * increment all phandles in it by that value. */ uint32_t phandle_base = tree->max_phandle; uint32_t new_max = dt_adjust_all_phandles(overlay->root, phandle_base); if (!new_max) { printk(BIOS_ERR, "invalid phandles in overlay\n"); return -1; } tree->max_phandle = new_max; /* Now that we changed phandles in the overlay, we need to update any nodes referring to them. Those are listed in /__local_fixups__. */ struct device_tree_node *local_fixups = dt_find_node_by_path(overlay, "/__local_fixups__", NULL, NULL, 0); if (local_fixups && dt_fixup_locals(overlay->root, local_fixups, phandle_base) < 0) { printk(BIOS_ERR, "invalid local fixups in overlay\n"); return -1; } /* * Besides local phandle references (from nodes within the overlay to * other nodes within the overlay), the overlay may also contain phandle * references to the base tree. These are stored with invalid values and * must be updated now. /__symbols__ contains a list of all labels in * the base tree, and /__fixups__ describes all nodes in the overlay * that contain external phandle references. * We also take this opportunity to update all /fragment@X/__overlay__/ * prefixes in the overlay's /__symbols__ node to the correct path that * the fragment will be placed in later, since this is the only step * where we have all necessary information for that easily available. */ struct device_tree_node *symbols = dt_find_node_by_path(tree, "/__symbols__", NULL, NULL, 0); struct device_tree_node *fixups = dt_find_node_by_path(overlay, "/__fixups__", NULL, NULL, 0); struct device_tree_node *overlay_symbols = dt_find_node_by_path(overlay, "/__symbols__", NULL, NULL, 0); if (fixups && dt_fixup_all_externals(tree, symbols, overlay, fixups, overlay_symbols) < 0) { printk(BIOS_ERR, "cannot match external fixups from overlay\n"); return -1; } /* After all this fixing up, we can finally merge overlay into the tree (one fragment at a time, because for some reason it's split up). */ struct device_tree_node *fragment; list_for_each(fragment, overlay->root->children, list_node) if (dt_import_fragment(tree, fragment, overlay_symbols) < 0) { printk(BIOS_ERR, "bad DT fragment '%s'\n", fragment->name); return -1; } /* * We need to also update /__symbols__ to include labels from this * overlay, in case we want to load further overlays with external * phandle references to it. If the base tree already has a /__symbols__ * we merge them together, otherwise we just insert the overlay's * /__symbols__ node into the base tree root. */ if (overlay_symbols) { if (symbols) dt_copy_subtree(symbols, overlay_symbols, 0); else list_insert_after(&overlay_symbols->list_node, &tree->root->children); } return 0; }