[PATCH] of: base: Add of_get_available_child_by_name()

[Biju Das]

There are lot of drivers using of_get_child_by_name() followed
by of_device_is_available() to check the child node availabilty
by name for a given parent. Provide a helper for these users to
simplify the code.

Suggested-by: Geert Uytterhoeven <geert+renesas at glider.be>
Signed-off-by: Biju Das <biju.das.jz at bp.renesas.com>
---
grep showed the below files will be the user for this new API.
I will be updating these drivers once this patch is in mainline.

drivers/net/dsa/rzn1_a5psw.c
drivers/net/can/rcar/rcar_canfd.c

drivers/net/ethernet/mediatek/mtk_star_emac.c
drivers/net/dsa/mt7530.c
drivers/net/dsa/sja1105/sja1105_mdio.c
drivers/net/dsa/qca/qca8k-8xxx.c
drivers/net/wireless/mediatek/mt76/mac80211.c
drivers/net/ethernet/ibm/emac/core.c
drivers/net/ethernet/ti/am65-cpsw-nuss.c
drivers/net/ethernet/actions/owl-emac.c
drivers/net/ethernet/mediatek/mtk_eth_soc.c
drivers/media/platform/samsung/exynos4-is/media-dev.h
drivers/gpu/drm/tegra/rgb.c
drivers/gpu/drm/msm/adreno/adreno_gpu.c
drivers/clk/davinci/pll.c
---
 drivers/of/base.c  | 28 ++++++++++++++++++++++++++++
 include/linux/of.h |  9 +++++++++
 2 files changed, 37 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index af6c68bbb427..3f5119fbfdb4 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -824,6 +824,34 @@ struct device_node *of_get_child_by_name(const struct device_node *node,
 }
 EXPORT_SYMBOL(of_get_child_by_name);
 
+/**
+ * of_get_available_child_by_name - Find the child node availabilty by name for a given parent
+ * @node:	parent node
+ * @name:	child name to look for.
+ *
+ * This function looks for child node for given matching name and check the
+ * device availability for use.
+ *
+ * Return: A node pointer if found, with refcount incremented, use
+ * of_node_put() on it when done.
+ * Returns NULL if node is not found.
+ */
+struct device_node *of_get_available_child_by_name(const struct device_node *node,
+						   const char *name)
+{
+	struct device_node *child;
+
+	for_each_child_of_node(node, child)
+		if (of_node_name_eq(child, name))
+			break;
+
+	if (child && !of_device_is_available(child))
+		of_node_put(child);
+
+	return child;
+}
+EXPORT_SYMBOL(of_get_available_child_by_name);
+
 struct device_node *__of_find_node_by_path(const struct device_node *parent,
 						const char *path)
 {
diff --git a/include/linux/of.h b/include/linux/of.h
index eaf0e2a2b75c..9d6b8a61607f 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -301,6 +301,8 @@ extern struct device_node *of_get_compatible_child(const struct device_node *par
 					const char *compatible);
 extern struct device_node *of_get_child_by_name(const struct device_node *node,
 					const char *name);
+extern struct device_node *of_get_available_child_by_name(const struct device_node *node,
+							  const char *name);
 
 /* cache lookup */
 extern struct device_node *of_find_next_cache_node(const struct device_node *);
@@ -578,6 +580,13 @@ static inline struct device_node *of_get_child_by_name(
 	return NULL;
 }
 
+static inline struct device_node *of_get_available_child_by_name(
+					const struct device_node *node,
+					const char *name)
+{
+	return NULL;
+}
+
 static inline int of_device_is_compatible(const struct device_node *device,
 					  const char *name)
 {
-- 
2.43.0