rust: Fix x86 build

Signed-off-by: Hector Martin <marcan@marcan.st>

Author: marcan

rust/helpers/of.c

@@ -8,10 +8,13 @@ const struct of_device_id *rust_helper_of_match_device(
 {
 			return of_match_device(matches, dev);
 }
+
+#ifdef CONFIG_OF
 bool rust_helper_of_node_is_root(const struct device_node *np)
 {
 	return of_node_is_root(np);
 }
+#endif
 
 struct device_node *rust_helper_of_parse_phandle(const struct device_node *np,
                const char *phandle_name,

rust/kernel/of.rs

@@ -119,7 +119,15 @@ impl Node {
 
     /// Returns `true` if the node is the root node.
     pub fn is_root(&self) -> bool {
-        unsafe { bindings::of_node_is_root(self.raw_node) }
+        #[cfg(not(CONFIG_OF))]
+        {
+            false
+        }
+        #[cfg(CONFIG_OF)]
+        // SAFETY: `raw_node` is valid per the type invariant
+        unsafe {
+            bindings::of_node_is_root(self.raw_node)
+        }
     }
 
     /// Returns the parent node, if any.
@@ -452,22 +460,54 @@ where
 
 /// Returns the root node of the OF device tree (if any).
 pub fn root() -> Option<Node> {
-    unsafe { Node::get_from_raw(bindings::of_root) }
+    #[cfg(not(CONFIG_OF))]
+    {
+        None
+    }
+    #[cfg(CONFIG_OF)]
+    // SAFETY: bindings::of_root is always valid or NULL
+    unsafe {
+        Node::get_from_raw(bindings::of_root)
+    }
 }
 
 /// Returns the /chosen node of the OF device tree (if any).
 pub fn chosen() -> Option<Node> {
-    unsafe { Node::get_from_raw(bindings::of_chosen) }
+    #[cfg(not(CONFIG_OF))]
+    {
+        None
+    }
+    #[cfg(CONFIG_OF)]
+    // SAFETY: bindings::of_chosen is always valid or NULL
+    unsafe {
+        Node::get_from_raw(bindings::of_chosen)
+    }
 }
 
 /// Returns the /aliases node of the OF device tree (if any).
 pub fn aliases() -> Option<Node> {
-    unsafe { Node::get_from_raw(bindings::of_aliases) }
+    #[cfg(not(CONFIG_OF))]
+    {
+        None
+    }
+    #[cfg(CONFIG_OF)]
+    // SAFETY: bindings::of_aliases is always valid or NULL
+    unsafe {
+        Node::get_from_raw(bindings::of_aliases)
+    }
 }
 
 /// Returns the system stdout node of the OF device tree (if any).
 pub fn stdout() -> Option<Node> {
-    unsafe { Node::get_from_raw(bindings::of_stdout) }
+    #[cfg(not(CONFIG_OF))]
+    {
+        None
+    }
+    #[cfg(CONFIG_OF)]
+    // SAFETY: bindings::of_stdout is always valid or NULL
+    unsafe {
+        Node::get_from_raw(bindings::of_stdout)
+    }
 }
 
 #[allow(unused_variables)]