Eliminate warnings in the auto-generated device tree

Move the module declaration for the device tree up into `lib.rs` to
allow insertion of allow directives to eliminate documentation warnings
on the generated devicetree.

Signed-off-by: David Brown <[email protected]>

Author: d3zd3z

zephyr-build/src/devicetree/output.rs

@@ -18,15 +18,15 @@ impl DeviceTree {
     pub fn to_tokens(&self) -> TokenStream {
         let augments = get_augments();
 
-        // Root is a little special, as we don't represent the name of the node as it's actual name,
-        // but as just 'devicetree'.
-        self.node_walk(self.root.as_ref(), "devicetree", &augments)
+        // Root is a little special.  Since we don't want a module for this (it will be provided
+        // above where it is included, so it can get documentation and attributes), we use None for
+        // the name.
+        self.node_walk(self.root.as_ref(), None, &augments)
     }
 
-    fn node_walk(&self, node: &Node, name: &str, augments: &[Box<dyn Augment>]) -> TokenStream {
-        let name_id = dt_to_lower_id(name);
+    fn node_walk(&self, node: &Node, name: Option<&str>, augments: &[Box<dyn Augment>]) -> TokenStream {
         let children = node.children.iter().map(|child| {
-            self.node_walk(child.as_ref(), &child.name, augments)
+            self.node_walk(child.as_ref(), Some(&child.name), augments)
         });
         // Simplistic first pass, turn the properties into constents of the formatted text of the
         // property.
@@ -52,12 +52,21 @@ impl DeviceTree {
         // If this is compatible with an augment, use the augment to add any additional properties.
         let augs = augments.iter().map(|aug| aug.augment(node, self));
 
-        quote! {
-            pub mod #name_id {
-                pub const ORD: usize = #ord;
+        if let Some(name) = name {
+            let name_id = dt_to_lower_id(name);
+            quote! {
+                pub mod #name_id {
+                    pub const ORD: usize = #ord;
+                    #(#props)*
+                    #(#children)*
+                    // #parent
+                    #(#augs)*
+                }
+            }
+        } else {
+            quote! {
                 #(#props)*
                 #(#children)*
-                // #parent
                 #(#augs)*
             }
         }

zephyr/src/lib.rs

@@ -41,8 +41,21 @@ pub mod kconfig {
     include!(concat!(env!("OUT_DIR"), "/kconfig.rs"));
 }
 
-// And the generated devicetree.
-include!(concat!(env!("OUT_DIR"), "/devicetree.rs"));
+pub mod devicetree {
+    //! Zephyr device tree
+    //!
+    //! This is an auto-generated module that represents the device tree for a given build.  The
+    //! hierarchy here should match the device tree, with an additional top-level module "labels"
+    //! that contains submodules for all of the labels.
+    //!
+    //! **Note**: Unless you are viewing docs generated for a specific build, the values below are
+    //! unlikely to directly correspond to those in a given build.
+
+    // Don't enforce doc comments on the generated device tree.
+    #![allow(missing_docs)]
+
+    include!(concat!(env!("OUT_DIR"), "/devicetree.rs"));
+}
 
 // Ensure that Rust is enabled.
 #[cfg(not(CONFIG_RUST))]