powerpc/pseries: extract of_helpers module

Extract a new module to share the code between other modules.

There is no functional change.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 38 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/pseries/of_helpers.c b/arch/powerpc/platforms/pseries/of_helpers.c
new file mode 100644
index 000000000000..1cbd89614484
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/of_helpers.c
@@ -0,0 +1,38 @@
+#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 = NULL;
+	char *parent_path = "/";
+	size_t parent_path_len = strrchr(path, '/') - path + 1;
+
+	/* reject if path is "/" */
+	if (!strcmp(path, "/"))
+		return ERR_PTR(-EINVAL);
+
+	if (strrchr(path, '/') != path) {
+		parent_path = kmalloc(parent_path_len, GFP_KERNEL);
+		if (!parent_path)
+			return ERR_PTR(-ENOMEM);
+		strlcpy(parent_path, path, parent_path_len);
+	}
+	parent = of_find_node_by_path(parent_path);
+	if (!parent)
+		return ERR_PTR(-EINVAL);
+	if (strcmp(parent_path, "/"))
+		kfree(parent_path);
+	return parent;
+}