[PATCH v6 02/12] of: base: Add for_each_child_of_node_with_prefix_scoped()

Chen-Yu Tsai
2024-09-04T09:00:32Z

There are cases where drivers would go through child device nodes and
operate on only the ones whose node name starts with a given prefix.

Provide a helper for these users. This will mainly be used in a
subsequent patch that implements a hardware component prober for I2C
busses.

Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
---
Changes since v5:
- New patch
---
drivers/of/base.c | 35 +++++++++++++++++++++++++++++++++++
include/linux/of.h | 9 +++++++++
2 files changed, 44 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 20603d3c9931..d3c123b3261a 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -628,6 +628,41 @@ struct device_node *of_get_next_child(const struct device_node *node,
}
EXPORT_SYMBOL(of_get_next_child);

+/**
+ * of_get_next_child_with_prefix - Find the next child node with prefix
+ * @node: parent node
+ * @prev: previous child of the parent node, or NULL to get first
+ *
+ * This function is like of_get_next_child(), except that it automatically
+ * skips any nodes whose name doesn't have the given prefix.
+ *
+ * Return: A node pointer with refcount incremented, use
+ * of_node_put() on it when done.
+ */
+struct device_node *of_get_next_child_with_prefix(const struct device_node *node,
+ struct device_node *prev,
+ const char *prefix)
+{
+ struct device_node *next;
+ unsigned long flags;
+
+ if (!node)
+ return NULL;
+
+ raw_spin_lock_irqsave(&devtree_lock, flags);
+ next = prev ? prev->sibling : node->child;
+ for (; next; next = next->sibling) {
+ if (!of_node_name_prefix(next, prefix))
+ continue;
+ if (of_node_get(next))
+ break;
+ }
+ of_node_put(prev);
+ raw_spin_unlock_irqrestore(&devtree_lock, flags);
+ return next;
+}
+EXPORT_SYMBOL(of_get_next_child_with_prefix);
+
static struct device_node *of_get_next_status_child(const struct device_node *node,
struct device_node *prev,
bool (*checker)(const struct device_node *))
diff --git a/include/linux/of.h b/include/linux/of.h
index 046283be1cd3..acc0d5b98417 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -289,6 +289,9 @@ 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 device_node *of_get_next_child_with_prefix(const struct device_node *node,
+ struct device_node *prev,
+ const char *prefix);
extern struct device_node *of_get_next_available_child(
const struct device_node *node, struct device_node *prev);
extern struct device_node *of_get_next_reserved_child(
@@ -1468,6 +1471,12 @@ static inline int of_property_read_s32(const struct device_node *np,
child != NULL; \
child = of_get_next_child(parent, child))

+#define for_each_child_of_node_with_prefix_scoped(parent, child, prefix) \
+ for (struct device_node *child __free(device_node) = \
+ of_get_next_child_with_prefix(parent, NULL, prefix); \
+ child != NULL; \
+ child = of_get_next_child_with_prefix(parent, child, prefix))
+
#define for_each_available_child_of_node(parent, child) \
for (child = of_get_next_available_child(parent, NULL); child != NULL; \
child = of_get_next_available_child(parent, child))
--
2.46.0.469.g59c65b2a67-goog