[PATCH 5.10 479/491] device property: Add fwnode_is_ancestor_of() and fwnode_get_next_parent_dev()

Greg Kroah-Hartman
2026-04-13T17:03:21Z

From: Saravana Kannan <saravanak@google.com>

[ Upstream commit b5d3e2fbcb10957521af14c4256cd0e5f68b9234 ]

Add fwnode_is_ancestor_of() helper function to check if a fwnode is an
ancestor of another fwnode.

Add fwnode_get_next_parent_dev() helper function that take as input a
fwnode and finds the closest ancestor fwnode that has a corresponding
struct device and returns that struct device.

Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20201121020232.908850-11-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 2692c614f8f0 ("device property: Allow secondary lookup in fwnode_get_next_child_node()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/base/property.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++
include/linux/property.h | 3 ++
2 files changed, 55 insertions(+)

--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -615,6 +615,31 @@ struct fwnode_handle *fwnode_get_next_pa
EXPORT_SYMBOL_GPL(fwnode_get_next_parent);

/**
+ * fwnode_get_next_parent_dev - Find device of closest ancestor fwnode
+ * @fwnode: firmware node
+ *
+ * Given a firmware node (@fwnode), this function finds its closest ancestor
+ * firmware node that has a corresponding struct device and returns that struct
+ * device.
+ *
+ * The caller of this function is expected to call put_device() on the returned
+ * device when they are done.
+ */
+struct device *fwnode_get_next_parent_dev(struct fwnode_handle *fwnode)
+{
+ struct device *dev = NULL;
+
+ fwnode_handle_get(fwnode);
+ do {
+ fwnode = fwnode_get_next_parent(fwnode);
+ if (fwnode)
+ dev = get_dev_from_fwnode(fwnode);
+ } while (fwnode && !dev);
+ fwnode_handle_put(fwnode);
+ return dev;
+}
+
+/**
* fwnode_count_parents - Return the number of parents a node has
* @fwnode: The node the parents of which are to be counted
*
@@ -661,6 +686,33 @@ struct fwnode_handle *fwnode_get_nth_par
EXPORT_SYMBOL_GPL(fwnode_get_nth_parent);

/**
+ * fwnode_is_ancestor_of - Test if @test_ancestor is ancestor of @test_child
+ * @test_ancestor: Firmware which is tested for being an ancestor
+ * @test_child: Firmware which is tested for being the child
+ *
+ * A node is considered an ancestor of itself too.
+ *
+ * Returns true if @test_ancestor is an ancestor of @test_child.
+ * Otherwise, returns false.
+ */
+bool fwnode_is_ancestor_of(struct fwnode_handle *test_ancestor,
+ struct fwnode_handle *test_child)
+{
+ if (!test_ancestor)
+ return false;
+
+ fwnode_handle_get(test_child);
+ while (test_child) {
+ if (test_child == test_ancestor) {
+ fwnode_handle_put(test_child);
+ return true;
+ }
+ test_child = fwnode_get_next_parent(test_child);
+ }
+ return false;
+}
+
+/**
* fwnode_get_next_child_node - Return the next child node handle for a node
* @fwnode: Firmware node to find the next child node for.
* @child: Handle to one of the node's child nodes or a %NULL handle.
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -85,9 +85,12 @@ const char *fwnode_get_name_prefix(const
struct fwnode_handle *fwnode_get_parent(const struct fwnode_handle *fwnode);
struct fwnode_handle *fwnode_get_next_parent(
struct fwnode_handle *fwnode);
+struct device *fwnode_get_next_parent_dev(struct fwnode_handle *fwnode);
unsigned int fwnode_count_parents(const struct fwnode_handle *fwn);
struct fwnode_handle *fwnode_get_nth_parent(struct fwnode_handle *fwn,
unsigned int depth);
+bool fwnode_is_ancestor_of(struct fwnode_handle *test_ancestor,
+ struct fwnode_handle *test_child);
struct fwnode_handle *fwnode_get_next_child_node(
const struct fwnode_handle *fwnode, struct fwnode_handle *child);
struct fwnode_handle *fwnode_get_next_available_child_node(