[PATCH 1/3] core/device: Add function to return child node using name and length

[Athira Rajeev <atrajeev@linux.vnet.ibm.com>]

Add a function dt_find_by_name_len() that returns the child node if
it matches the first "n" characters of a given name, otherwise NULL.
This is helpful for cases with node name like: "name@addr". In
scenarios where nodes are added with "name@addr" format and if the
value of "addr" is not known, that node can't be matched with node
name or addr. Hence matching with substring as node name will return
the expected result. Patch adds dt_find_by_name_len() function
and testcase for the same in core/test/run-device.c

Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
---
 core/device.c          | 20 ++++++++++++++++++++
 core/test/run-device.c | 11 +++++++++++
 include/device.h       |  4 ++++
 3 files changed, 35 insertions(+)

diff --git a/core/device.c b/core/device.c
index 2de37c74..72c54e85 100644
--- a/core/device.c
+++ b/core/device.c
@@ -395,6 +395,26 @@ struct dt_node *dt_find_by_name(struct dt_node *root, const char *name)
 }
 
 
+struct dt_node *dt_find_by_name_len(struct dt_node *root,
+					const char *name, int len)
+{
+	struct dt_node *child, *match;
+
+	if (len <= 0)
+		return NULL;
+
+	list_for_each(&root->children, child, list) {
+		if (!strncmp(child->name, name, len))
+			return child;
+
+		match = dt_find_by_name_len(child, name, len);
+		if (match)
+			return match;
+	}
+
+	return NULL;
+}
+
 struct dt_node *dt_new_check(struct dt_node *parent, const char *name)
 {
 	struct dt_node *node = dt_find_by_name(parent, name);
diff --git a/core/test/run-device.c b/core/test/run-device.c
index 4a12382b..8c552103 100644
--- a/core/test/run-device.c
+++ b/core/test/run-device.c
@@ -466,6 +466,17 @@ int main(void)
 	new_prop_ph = dt_prop_get_u32(ut2, "something");
 	assert(!(new_prop_ph == ev1_ph));
 	dt_free(subtree);
+
+	/* Test dt_find_by_name_len */
+	root = dt_new_root("");
+	addr1 = dt_new_addr(root, "node", 0x1);
+	addr2 = dt_new_addr(root, "node0_1", 0x2);
+	assert(dt_find_by_name(root, "node@1") == addr1);
+	assert(dt_find_by_name(root, "node0_1@2") == addr2);
+	assert(dt_find_by_name_len(root, "node@", 5) == addr1);
+	assert(dt_find_by_name_len(root, "node0_1@", 8) == addr2);
+	dt_free(root);
+
 	return 0;
 }
 
diff --git a/include/device.h b/include/device.h
index 93fb90ff..f5e0fb79 100644
--- a/include/device.h
+++ b/include/device.h
@@ -184,6 +184,10 @@ struct dt_node *dt_find_by_path(struct dt_node *root, const char *path);
 /* Find a child node by name */
 struct dt_node *dt_find_by_name(struct dt_node *root, const char *name);
 
+/* Find a child node by name and len */
+struct dt_node *dt_find_by_name_len(struct dt_node *root,
+                                        const char *name, int len);
+
 /* Find a node by phandle */
 struct dt_node *dt_find_by_phandle(struct dt_node *root, u32 phandle);
 
-- 
2.27.0