Re: [PATCH 2/3] of: Make of_find_node_by_path() handle /aliases
From: Frank Rowand <hidden>
Date: 2014-05-16 02:51:24
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lkml
On 5/13/2014 7:58 AM, Grant Likely wrote:
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Make of_find_node_by_path() handle aliases as prefixes. To make this work the name search is refactored to search by path component instead of by full string. This should be a more efficient search, and it makes it possible to start a search at a subnode of a tree. Signed-off-by: David Daney <redacted> Signed-off-by: Pantelis Antoniou <redacted> [grant.likely: Rework to not require allocating at runtime] Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Grant Likely <redacted> --- drivers/of/base.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 56 insertions(+), 4 deletions(-)diff --git a/drivers/of/base.c b/drivers/of/base.c index 6e240698353b..60089b9a3014 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c@@ -771,9 +771,38 @@ struct device_node *of_get_child_by_name(const struct device_node *node, } EXPORT_SYMBOL(of_get_child_by_name); +static struct device_node *__of_find_node_by_path(struct device_node *parent, + const char *path) +{ + struct device_node *child; + int len = strchrnul(path, '/') - path; + + if (!len) + return parent;
(!len) is true if the the final character of the path passed into of_find_node_by_path() was "/". Strictly speaking, ->full_name will never end with "/", so the return value should be NULL, indicating that the match fails.
+
+ for_each_child_of_node(parent, child) {
+ const char *name = strrchr(child->full_name, '/');
+ if (WARN(!name, "malformed device_node %s\n", child->full_name))
+ continue;
+ name++;Why go to the effort of finding the final component of child->full_name instead of just using child->name?
+ if (strncmp(path, name, len) == 0 && (strlen(name) == len)) + return child; + } + return NULL; +} + /** * of_find_node_by_path - Find a node matching a full OF path * @path: The full path to match + * @path: Either the full path to match, or if the path does not
Delete the old @path description.
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+ * start with '/', the name of a property of the /aliases + * node (an alias). In the case of an alias, the node + * matching the alias' value will be returned. + * + * Valid paths: + * /foo/bar Full path + * foo Valid alias + * foo/bar Valid alias + relative path * * Returns a node pointer with refcount incremented, use * of_node_put() on it when done.@@ -781,13 +810,36 @@ EXPORT_SYMBOL(of_get_child_by_name); struct device_node *of_find_node_by_path(const char *path) { struct device_node *np = of_allnodes; + struct property *pp; unsigned long flags; + /* The path could begin with an alias */ + if (*path != '/') { + char *p = strchrnul(path, '/'); + int len = p - path; + + /* of_aliases must not be NULL */ + if (!of_aliases) + return NULL; + + np = NULL; + for_each_property_of_node(of_aliases, pp) { + if (strlen(pp->name) == len && !strncmp(pp->name, path, len)) { + np = of_find_node_by_path(pp->value); + break; + } + } + if (!np) + return NULL; + path = p; + } + + /* Step down the tree matching path components */ raw_spin_lock_irqsave(&devtree_lock, flags); - for (; np; np = np->allnext) { - if (np->full_name && (of_node_cmp(np->full_name, path) == 0) - && of_node_get(np)) - break; + while (np && *path == '/') { + path++; /* Increment past '/' delimiter */ + np = __of_find_node_by_path(np, path); + path = strchrnul(path, '/'); } raw_spin_unlock_irqrestore(&devtree_lock, flags); return np;