On 5/13/2014 7:58 AM, Grant Likely wrote:
> 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 <david.daney@xxxxxxxxxx>
> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx>
> [grant.likely: Rework to not require allocating at runtime]
> Acked-by: Rob Herring <robh@xxxxxxxxxx>
> Signed-off-by: Grant Likely <grant.likely@xxxxxxxxxx>
> ---
> 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.
> + * 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;
>
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