rust: of: Add OF node abstraction

This abstraction enables Rust drivers to walk Device Tree nodes and
query their properties.

Signed-off-by: Asahi Lina <lina@asahilina.net>

Author: hoshinolina

rust/bindings/bindings_helper.h

@@ -25,6 +25,8 @@
 #include <linux/ktime.h>
 #include <linux/lockdep.h>
 #include <linux/mdio.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
 #include <linux/of_device.h>
 #include <linux/pci.h>
 #include <linux/phy.h>

rust/helpers/of.c

@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+const struct of_device_id *rust_helper_of_match_device(
+		const struct of_device_id *matches, const struct device *dev)
+{
+			return of_match_device(matches, dev);
+}
+bool rust_helper_of_node_is_root(const struct device_node *np)
+{
+	return of_node_is_root(np);
+}
+
+struct device_node *rust_helper_of_parse_phandle(const struct device_node *np,
+               const char *phandle_name,
+               int index)
+{
+	return of_parse_phandle(np, phandle_name, index);
+}