From f4eb010706b6c96c136c7aaa9079159743f33fa8 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Fri, 26 Oct 2007 16:54:31 +1000 Subject: [POWERPC] Add of_get_next_parent() Iterating through a device node's parents is simple enough, but dealing with the refcounts properly is a little ugly, and replicating that logic is asking for someone to get it wrong or forget it all together, eg: while (dn != NULL) { /* loop body */ tmp = of_get_parent(dn); of_node_put(dn); dn = tmp; } So add of_get_next_parent(), inspired by of_get_next_child(). The contract is that it returns the parent and drops the reference on the current node, this makes the loop look like: while (dn != NULL) { /* loop body */ dn = of_get_next_parent(dn); } Signed-off-by: Michael Ellerman Acked-by: David S. Miller Signed-off-by: Paul Mackerras --- drivers/of/base.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) (limited to 'drivers') diff --git a/drivers/of/base.c b/drivers/of/base.c index b306fef1ac4..80c9deca5f3 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -137,6 +137,31 @@ struct device_node *of_get_parent(const struct device_node *node) } EXPORT_SYMBOL(of_get_parent); +/** + * of_get_next_parent - Iterate to a node's parent + * @node: Node to get parent of + * + * This is like of_get_parent() except that it drops the + * refcount on the passed node, making it suitable for iterating + * through a node's parents. + * + * Returns a node pointer with refcount incremented, use + * of_node_put() on it when done. + */ +struct device_node *of_get_next_parent(struct device_node *node) +{ + struct device_node *parent; + + if (!node) + return NULL; + + read_lock(&devtree_lock); + parent = of_node_get(node->parent); + of_node_put(node); + read_unlock(&devtree_lock); + return parent; +} + /** * of_get_next_child - Iterate a node childs * @node: parent node -- cgit v1.2.3-70-g09d2