1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/string.h>
3 #include <linux/err.h>
4 #include <linux/slab.h>
5 #include <linux/of.h>
6 
7 #include "of_helpers.h"
8 
9 /**
10  * pseries_of_derive_parent - basically like dirname(1)
11  * @path:  the full_name of a node to be added to the tree
12  *
13  * Returns the node which should be the parent of the node
14  * described by path.  E.g., for path = "/foo/bar", returns
15  * the node with full_name = "/foo".
16  */
17 struct device_node *pseries_of_derive_parent(const char *path)
18 {
19 	struct device_node *parent;
20 	char *parent_path = "/";
21 	const char *tail;
22 
23 	/* We do not want the trailing '/' character */
24 	tail = kbasename(path) - 1;
25 
26 	/* reject if path is "/" */
27 	if (!strcmp(path, "/"))
28 		return ERR_PTR(-EINVAL);
29 
30 	if (tail > path) {
31 		parent_path = kstrndup(path, tail - path, GFP_KERNEL);
32 		if (!parent_path)
33 			return ERR_PTR(-ENOMEM);
34 	}
35 	parent = of_find_node_by_path(parent_path);
36 	if (strcmp(parent_path, "/"))
37 		kfree(parent_path);
38 	return parent ? parent : ERR_PTR(-EINVAL);
39 }
40