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 <[EMAIL PROTECTED]>
---
drivers/of/base.c | 25 +++++++++++++++++++++++++
include/linux/of.h | 1 +
2 files changed, 26 insertions(+), 0 deletions(-)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 9377f3b..e0db2b5 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -138,6 +138,31 @@ 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
* @prev: previous child of the parent node, or NULL to get first
diff --git a/include/linux/of.h b/include/linux/of.h
index 5c39b92..3557d1e 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -44,6 +44,7 @@ extern struct device_node *of_find_compatible_node(struct
device_node *from,
extern struct device_node *of_find_node_by_path(const char *path);
extern struct device_node *of_find_node_by_phandle(phandle handle);
extern struct device_node *of_get_parent(const struct device_node *node);
+extern struct device_node *of_get_next_parent(struct device_node *node);
extern struct device_node *of_get_next_child(const struct device_node *node,
struct device_node *prev);
extern struct property *of_find_property(const struct device_node *np,
--
1.5.2.rc1.1884.g59b20
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