of_helpers.c
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#include <linux/string.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/of.h>
#include "of_helpers.h"
/**
* pseries_of_derive_parent - basically like dirname(1)
* @path: the full_name of a node to be added to the tree
*
* Returns the node which should be the parent of the node
* described by path. E.g., for path = "/foo/bar", returns
* the node with full_name = "/foo".
*/
struct device_node *pseries_of_derive_parent(const char *path)
{
struct device_node *parent;
char *parent_path = "/";
const char *tail;
/* We do not want the trailing '/' character */
tail = kbasename(path) - 1;
/* reject if path is "/" */
if (!strcmp(path, "/"))
return ERR_PTR(-EINVAL);
if (tail > path) {
parent_path = kstrndup(path, tail - path, GFP_KERNEL);
if (!parent_path)
return ERR_PTR(-ENOMEM);
}
parent = of_find_node_by_path(parent_path);
if (strcmp(parent_path, "/"))
kfree(parent_path);
return parent ? parent : ERR_PTR(-EINVAL);
}