linux-kernel - [PATCH v7 02/10] of: base: Add for_each_child_of_node_with

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Message-ID: <20240911072751.365361-3-wenst@chromium.org>
Date: Wed, 11 Sep 2024 15:27:40 +0800
From: Chen-Yu Tsai <wenst@...omium.org>
To: Rob Herring <robh@...nel.org>,
	Saravana Kannan <saravanak@...gle.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Wolfram Sang <wsa@...nel.org>,
	Benson Leung <bleung@...omium.org>,
	Tzung-Bi Shih <tzungbi@...nel.org>,
	Mark Brown <broonie@...nel.org>,
	Liam Girdwood <lgirdwood@...il.com>
Cc: Chen-Yu Tsai <wenst@...omium.org>,
	chrome-platform@...ts.linux.dev,
	devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Douglas Anderson <dianders@...omium.org>,
	Johan Hovold <johan@...nel.org>,
	Jiri Kosina <jikos@...nel.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	linux-i2c@...r.kernel.org
Subject: [PATCH v7 02/10] of: base: Add for_each_child_of_node_with_prefix()

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@...omium.org>
---
Changes since v6:
- Changed helper name to "for_each_child_of_node_with_prefix()"
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..48cfb39197d6 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(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))
-- 
2.46.0.598.g6f2099f65c-goog