rust: kernel: of: Fix !CONFIG_OF build

of_reserved_mem_region_to_resource_byname() has no empty implementation
for !OF.

Signed-off-by: Janne Grunau <[email protected]>

Author: jannau

rust/kernel/of.rs

@@ -214,20 +214,28 @@ impl Node {
         }
     }
 
+    #[allow(unused_variables)]
     /// Get a reserved memory region as a resource
     pub fn reserved_mem_region_to_resource_byname(&self, name: &CStr) -> Result<Resource> {
-        let res = Resource::zeroed();
-        // SAFETY: This function is safe to call as long as the arguments are valid pointers.
-        let ret = unsafe {
-            bindings::of_reserved_mem_region_to_resource_byname(
-                self.raw_node,
-                name.as_char_ptr(),
-                res.as_raw(),
-            )
-        };
-        to_result(ret)?;
-
-        Ok(res)
+        #[cfg(not(CONFIG_OF))]
+        {
+            Err(ENOENT)
+        }
+        #[cfg(CONFIG_OF)]
+        {
+            let res = Resource::zeroed();
+            // SAFETY: This function is safe to call as long as the arguments are valid pointers.
+            let ret = unsafe {
+                bindings::of_reserved_mem_region_to_resource_byname(
+                    self.raw_node,
+                    name.as_char_ptr(),
+                    res.as_raw(),
+                )
+            };
+            to_result(ret)?;
+
+            Ok(res)
+        }
     }
 
     #[allow(unused_variables)]