property: Add functions to iterate named child

There are a few use-cases where child nodes with a specific name need to
be parsed. Code like:

fwnode_for_each_child_node()
	if (fwnode_name_eq())
		...

can be found from a various drivers/subsystems. Adding a macro for this
can simplify things a bit.

In a few cases the data from the found nodes is later added to an array,
which is allocated based on the number of found nodes. One example of
such use is the IIO subsystem's ADC channel nodes, where the relevant
nodes are named as channel[@N].

Add helpers for iterating and counting device's sub-nodes with certain
name instead of open-coding this in every user.

Suggested-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Marcelo Schmitt <marcelo.schmitt1@gmail.com>
Link: https://patch.msgid.link/2767173b7b18e974c0bac244688214bd3863ff06.1742560649.git.mazziesaccount@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/include/linux/property.h b/include/linux/property.h
index e214ecd241eb..3e83babac0b0 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -167,6 +167,10 @@ struct fwnode_handle *fwnode_get_next_available_child_node(
 	for (child = fwnode_get_next_child_node(fwnode, NULL); child;	\
 	     child = fwnode_get_next_child_node(fwnode, child))
 
+#define fwnode_for_each_named_child_node(fwnode, child, name)		\
+	fwnode_for_each_child_node(fwnode, child)			\
+		if (!fwnode_name_eq(child, name)) { } else
+
 #define fwnode_for_each_available_child_node(fwnode, child)		       \
 	for (child = fwnode_get_next_available_child_node(fwnode, NULL); child;\
 	     child = fwnode_get_next_available_child_node(fwnode, child))
@@ -178,11 +182,19 @@ struct fwnode_handle *device_get_next_child_node(const struct device *dev,
 	for (child = device_get_next_child_node(dev, NULL); child;	\
 	     child = device_get_next_child_node(dev, child))
 
+#define device_for_each_named_child_node(dev, child, name)		\
+	device_for_each_child_node(dev, child)				\
+		if (!fwnode_name_eq(child, name)) { } else
+
 #define device_for_each_child_node_scoped(dev, child)			\
 	for (struct fwnode_handle *child __free(fwnode_handle) =	\
 		device_get_next_child_node(dev, NULL);			\
 	     child; child = device_get_next_child_node(dev, child))
 
+#define device_for_each_named_child_node_scoped(dev, child, name)	\
+	device_for_each_child_node_scoped(dev, child)			\
+		if (!fwnode_name_eq(child, name)) { } else
+
 struct fwnode_handle *fwnode_get_named_child_node(const struct fwnode_handle *fwnode,
 						  const char *childname);
 struct fwnode_handle *device_get_named_child_node(const struct device *dev,
@@ -210,6 +222,14 @@ int fwnode_irq_get_byname(const struct fwnode_handle *fwnode, const char *name);
 
 unsigned int device_get_child_node_count(const struct device *dev);
 
+unsigned int fwnode_get_named_child_node_count(const struct fwnode_handle *fwnode,
+					       const char *name);
+static inline unsigned int device_get_named_child_node_count(const struct device *dev,
+							     const char *name)
+{
+	return fwnode_get_named_child_node_count(dev_fwnode(dev), name);
+}
+
 static inline int device_property_read_u8(const struct device *dev,
 					  const char *propname, u8 *val)
 {