device_tree: Add support for aliases
This patch adds support to lookup nodes via the "/aliases" mechanism in device trees. This may be required for overlay support (don't quite remember tbh) and is also just a generally useful feature. It was adapted from depthcharge's http://crosreview.com/1249703 and http://crosreview.com/1542702. Change-Id: I1289ab2f02c4877a2d0111040384827e2b48a34a Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://review.coreboot.org/c/coreboot/+/32866 Reviewed-by: Hung-Te Lin <hungte@chromium.org> Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
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@ -146,6 +146,9 @@ struct device_tree_node *dt_find_node_by_phandle(struct device_tree_node *root,
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// represented as a string of '/' separated node names.
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struct device_tree_node *dt_find_node_by_path(struct device_tree *tree,
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const char *path, u32 *addrcp, u32 *sizecp, int create);
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// Look up a node through an alias.
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struct device_tree_node *dt_find_node_by_alias(struct device_tree *tree,
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const char *alias);
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// Look up a node relative to a parent node, through its compatible string.
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struct device_tree_node *dt_find_compat(struct device_tree_node *parent, const char *compatible);
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// Look up the next child of a parent node, through its compatible string. It
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@ -564,27 +564,65 @@ struct device_tree_node *dt_find_node(struct device_tree_node *parent,
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* @param create 1: Create node(s) if not found. 0: Return NULL instead.
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* @return The found/created node, or NULL.
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*
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* It is the caller responsibility to provide the correct path string, namely
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* starting with a '/', not ending in a '/' and not having "//" anywhere in it.
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*/
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* It is the caller responsibility to provide a path string that doesn't end
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* with a '/' and doesn't contain any "//". If the path does not start with a
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* '/', the first segment is interpreted as an alias. */
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struct device_tree_node *dt_find_node_by_path(struct device_tree *tree,
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const char *path, u32 *addrcp,
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u32 *sizecp, int create)
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{
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char *dup_path = strdup(&path[1]); /* remove leading '/' */
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char *sub_path;
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char *duped_str;
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struct device_tree_node *parent;
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char *next_slash;
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/* Hopefully enough depth for any node. */
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const char *path_array[15];
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int i;
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char *next_slash;
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struct device_tree_node *node = NULL;
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if (!dup_path)
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return NULL;
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if (path[0] == '/') { // regular path
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if (path[1] == '\0') { // special case: "/" is root node
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dt_read_cell_props(tree->root, addrcp, sizecp);
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return tree->root;
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}
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next_slash = dup_path;
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path_array[0] = dup_path;
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sub_path = duped_str = strdup(&path[1]);
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if (!sub_path)
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return NULL;
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parent = tree->root;
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} else { // alias
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char *alias;
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alias = duped_str = strdup(path);
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if (!alias)
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return NULL;
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sub_path = strchr(alias, '/');
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if (sub_path)
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*sub_path = '\0';
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parent = dt_find_node_by_alias(tree, alias);
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if (!parent) {
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printk(BIOS_DEBUG,
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"Could not find node '%s', alias '%s' does not exist\n",
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path, alias);
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free(duped_str);
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return NULL;
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}
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if (!sub_path) {
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// it's just the alias, no sub-path
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free(duped_str);
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return parent;
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}
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sub_path++;
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}
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next_slash = sub_path;
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path_array[0] = sub_path;
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for (i = 1; i < (ARRAY_SIZE(path_array) - 1); i++) {
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next_slash = strchr(next_slash, '/');
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if (!next_slash)
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break;
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@ -595,14 +633,38 @@ struct device_tree_node *dt_find_node_by_path(struct device_tree *tree,
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if (!next_slash) {
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path_array[i] = NULL;
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node = dt_find_node(tree->root, path_array,
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node = dt_find_node(parent, path_array,
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addrcp, sizecp, create);
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}
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free(dup_path);
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free(duped_str);
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return node;
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}
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/*
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* Find a node from an alias
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*
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* @param tree The device tree.
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* @param alias The alias name.
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* @return The found node, or NULL.
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*/
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struct device_tree_node *dt_find_node_by_alias(struct device_tree *tree,
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const char *alias)
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{
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struct device_tree_node *node;
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const char *alias_path;
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node = dt_find_node_by_path(tree, "/aliases", NULL, NULL, 0);
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if (!node)
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return NULL;
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alias_path = dt_find_string_prop(node, alias);
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if (!alias_path)
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return NULL;
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return dt_find_node_by_path(tree, alias_path, NULL, NULL, 0);
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}
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struct device_tree_node *dt_find_node_by_phandle(struct device_tree_node *root,
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uint32_t phandle)
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{
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