Split bindings crate out of the main kernel crate

rust/Makefile

@@ -14,9 +14,10 @@ CFLAGS_REMOVE_helpers.o = -Wmissing-prototypes -Wmissing-declarations
 always-$(CONFIG_RUST) += libmacros.so
 no-clean-files += libmacros.so
 
-always-$(CONFIG_RUST) += bindings_generated.rs bindings_helpers_generated.rs
-obj-$(CONFIG_RUST) += alloc.o kernel.o
-always-$(CONFIG_RUST) += exports_alloc_generated.h exports_kernel_generated.h
+always-$(CONFIG_RUST) += bindings/bindings_generated.rs bindings/bindings_helpers_generated.rs
+obj-$(CONFIG_RUST) += alloc.o bindings.o kernel.o
+always-$(CONFIG_RUST) += exports_alloc_generated.h exports_bindings_generated.h \
+    exports_kernel_generated.h
 
 ifdef CONFIG_RUST_BUILD_ASSERT_DENY
 always-$(CONFIG_RUST) += build_error.o
@@ -110,10 +111,11 @@ rustdoc-alloc: $(src)/alloc/lib.rs rustdoc-core rustdoc-compiler_builtins FORCE
 	$(call if_changed,rustdoc)
 
 rustdoc-kernel: private rustc_target_flags = --extern alloc \
-    --extern build_error --extern macros=$(objtree)/$(obj)/libmacros.so
+    --extern build_error --extern macros=$(objtree)/$(obj)/libmacros.so \
+    --extern bindings
 rustdoc-kernel: $(src)/kernel/lib.rs rustdoc-core rustdoc-macros \
     rustdoc-compiler_builtins rustdoc-alloc $(obj)/libmacros.so \
-    $(obj)/bindings_generated.rs $(obj)/bindings_helpers_generated.rs FORCE
+    $(obj)/bindings.o FORCE
 	$(call if_changed,rustdoc)
 
 quiet_cmd_rustc_test_library = RUSTC TL $<
@@ -135,6 +137,9 @@ rusttestlib-macros: private rustc_test_library_proc = yes
 rusttestlib-macros: $(src)/macros/lib.rs rusttest-prepare FORCE
 	$(call if_changed,rustc_test_library)
 
+rusttestlib-bindings: $(src)/bindings/lib.rs rusttest-prepare FORCE
+	$(call if_changed,rustc_test_library)
+
 quiet_cmd_rustdoc_test = RUSTDOC T $<
       cmd_rustdoc_test = \
 	OBJTREE=$(abspath $(objtree)) \
@@ -154,6 +159,7 @@ quiet_cmd_rustdoc_test_kernel = RUSTDOC TK $<
 		@$(objtree)/include/generated/rustc_cfg \
 		-L$(objtree)/$(obj) --extern alloc --extern kernel \
 		--extern build_error --extern macros \
+		--extern bindings \
 		--no-run --crate-name kernel -Zunstable-options \
 		--test-builder $(srctree)/scripts/rustdoc_test_builder.py \
 		$< $(rustdoc_test_kernel_quiet); \
@@ -234,10 +240,9 @@ rusttest-macros: $(src)/macros/lib.rs rusttest-prepare FORCE
 	$(call if_changed,rustdoc_test)
 
 rusttest-kernel: private rustc_target_flags = --extern alloc \
-    --extern build_error --extern macros
-rusttest-kernel: private rustc_test_run_flags = --skip bindgen_test_layout_
+    --extern build_error --extern macros --extern bindings
 rusttest-kernel: $(src)/kernel/lib.rs rusttest-prepare \
-    rusttestlib-build_error rusttestlib-macros FORCE
+    rusttestlib-build_error rusttestlib-macros rusttestlib-bindings FORCE
 	$(call if_changed,rustc_test)
 	$(call if_changed,rustc_test_library)
 
@@ -302,24 +307,24 @@ quiet_cmd_bindgen = BINDGEN $@
 		--size_t-is-usize -o $@ -- $(bindgen_c_flags_final) -DMODULE \
 		$(bindgen_target_cflags) $(bindgen_target_extra)
 
-$(obj)/bindings_generated.rs: private bindgen_target_flags = \
+$(obj)/bindings/bindings_generated.rs: private bindgen_target_flags = \
     $(shell grep -v '^\#\|^$$' $(srctree)/$(src)/bindgen_parameters)
-$(obj)/bindings_generated.rs: $(src)/kernel/bindings_helper.h \
+$(obj)/bindings/bindings_generated.rs: $(src)/bindings/bindings_helper.h \
     $(src)/bindgen_parameters FORCE
 	$(call if_changed_dep,bindgen)
 
 # See `CFLAGS_REMOVE_helpers.o` above. In addition, Clang on C does not warn
 # with `-Wmissing-declarations` (unlike GCC), so it is not strictly needed here
 # given it is `libclang`; but for consistency, future Clang changes and/or
 # a potential future GCC backend for `bindgen`, we disable it too.
-$(obj)/bindings_helpers_generated.rs: private bindgen_target_flags = \
+$(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_flags = \
     --blacklist-type '.*' --whitelist-var '' \
     --whitelist-function 'rust_helper_.*'
-$(obj)/bindings_helpers_generated.rs: private bindgen_target_cflags = \
+$(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_cflags = \
     -I$(objtree)/$(obj) -Wno-missing-prototypes -Wno-missing-declarations
-$(obj)/bindings_helpers_generated.rs: private bindgen_target_extra = ; \
+$(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_extra = ; \
     sed -Ei 's/pub fn rust_helper_([a-zA-Z0-9_]*)/#[link_name="rust_helper_\1"]\n    pub fn \1/g' $@
-$(obj)/bindings_helpers_generated.rs: $(src)/helpers.c FORCE
+$(obj)/bindings/bindings_helpers_generated.rs: $(src)/helpers.c FORCE
 	$(call if_changed_dep,bindgen)
 
 quiet_cmd_exports = EXPORTS $@
@@ -335,6 +340,9 @@ $(obj)/exports_core_generated.h: $(obj)/core.o FORCE
 $(obj)/exports_alloc_generated.h: $(obj)/alloc.o FORCE
 	$(call if_changed,exports)
 
+$(obj)/exports_bindings_generated.h: $(obj)/bindings.o FORCE
+	$(call if_changed,exports)
+
 $(obj)/exports_kernel_generated.h: $(obj)/kernel.o FORCE
 	$(call if_changed,exports)
 
@@ -388,11 +396,16 @@ $(obj)/alloc.o: $(src)/alloc/lib.rs $(obj)/compiler_builtins.o FORCE
 $(obj)/build_error.o: $(src)/build_error.rs $(obj)/compiler_builtins.o FORCE
 	$(call if_changed_dep,rustc_library)
 
+$(obj)/bindings.o: $(src)/bindings/lib.rs \
+    $(obj)/compiler_builtins.o \
+    $(obj)/bindings/bindings_generated.rs \
+    $(obj)/bindings/bindings_helpers_generated.rs FORCE
+	$(call if_changed_dep,rustc_library)
+
 $(obj)/kernel.o: private rustc_target_flags = --extern alloc \
-    --extern build_error --extern macros
+    --extern build_error --extern macros --extern bindings
 $(obj)/kernel.o: $(src)/kernel/lib.rs $(obj)/alloc.o $(obj)/build_error.o \
-    $(obj)/libmacros.so $(obj)/bindings_generated.rs \
-    $(obj)/bindings_helpers_generated.rs FORCE
+    $(obj)/libmacros.so $(obj)/bindings.o FORCE
 	$(call if_changed_dep,rustc_library)
 
 endif # CONFIG_RUST

rust/kernel/bindings.rs → rust/bindings/lib.rs

@@ -3,13 +3,20 @@
 //! Bindings.
 //!
 //! Imports the generated bindings by `bindgen`.
+//!
+//! This crate may not be directly used. If you need a kernel C API that is
+//! not ported or wrapped in the `kernel` crate, then do so first instead of
+//! using this crate.
 
+#![no_std]
+#![feature(core_ffi_c)]
 // See https://github.com/rust-lang/rust-bindgen/issues/1651.
 #![cfg_attr(test, allow(deref_nullptr))]
 #![cfg_attr(test, allow(unaligned_references))]
 #![cfg_attr(test, allow(unsafe_op_in_unsafe_fn))]
 #![allow(
     clippy::all,
+    missing_docs,
     non_camel_case_types,
     non_upper_case_globals,
     non_snake_case,
@@ -22,7 +29,10 @@ mod bindings_raw {
     // Use glob import here to expose all helpers.
     // Symbols defined within the module will take precedence to the glob import.
     pub use super::bindings_helper::*;
-    include!(concat!(env!("OBJTREE"), "/rust/bindings_generated.rs"));
+    include!(concat!(
+        env!("OBJTREE"),
+        "/rust/bindings/bindings_generated.rs"
+    ));
 }
 
 // When both a directly exposed symbol and a helper exists for the same function,
@@ -34,7 +44,7 @@ mod bindings_helper {
     use super::bindings_raw::*;
     include!(concat!(
         env!("OBJTREE"),
-        "/rust/bindings_helpers_generated.rs"
+        "/rust/bindings/bindings_helpers_generated.rs"
     ));
 }
 

rust/exports.c

@@ -17,4 +17,5 @@
 
 #include "exports_core_generated.h"
 #include "exports_alloc_generated.h"
+#include "exports_bindings_generated.h"
 #include "exports_kernel_generated.h"

rust/kernel/lib.rs

@@ -39,7 +39,7 @@ compile_error!("Missing kernel configuration for conditional compilation");
 mod allocator;
 
 #[doc(hidden)]
-pub mod bindings;
+pub use bindings;
 
 #[cfg(CONFIG_ARM_AMBA)]
 pub mod amba;

scripts/generate_rust_analyzer.py

@@ -73,13 +73,20 @@ def append_crate(display_name, root_module, deps, cfg=[], is_workspace_member=Tr
         ["core", "compiler_builtins"],
     )
 
+    append_crate(
+        "bindings",
+        srctree / "rust"/ "bindings" / "lib.rs",
+        ["core"],
+        cfg=cfg,
+    )
+    crates[-1]["env"]["OBJTREE"] = str(objtree.resolve(True))
+
     append_crate(
         "kernel",
         srctree / "rust" / "kernel" / "lib.rs",
-        ["core", "alloc", "macros", "build_error"],
+        ["core", "alloc", "macros", "build_error", "bindings"],
         cfg=cfg,
     )
-    crates[-1]["env"]["OBJTREE"] = str(objtree.resolve(True))
     crates[-1]["source"] = {
         "include_dirs": [
             str(srctree / "rust" / "kernel"),