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