[PATCH v4 1/9] rust: module: move module types into `module.rs`

[Alvin Sun <alvin.sun@linux.dev>]

Move `Module`, `InPlaceModule`, `ModuleMetadata` and `ThisModule` from
`lib.rs` into a new `rust/kernel/module.rs`. Re-export them from `lib.rs`
to avoid tree-wide changes.

Switch six bus driver registrations from `module.0` to the public
`ThisModule::as_ptr()` accessor, since the field is no longer visible
outside the new `module` submodule.

No functional change.

Signed-off-by: Alvin Sun <alvin.sun@linux.dev>
---
 rust/kernel/auxiliary.rs |  2 +-
 rust/kernel/i2c.rs       |  2 +-
 rust/kernel/lib.rs       | 75 +++++-------------------------------------------
 rust/kernel/module.rs    | 71 +++++++++++++++++++++++++++++++++++++++++++++
 rust/kernel/net/phy.rs   |  6 +++-
 rust/kernel/pci.rs       |  2 +-
 rust/kernel/platform.rs  |  2 +-
 rust/kernel/usb.rs       |  2 +-
 8 files changed, 88 insertions(+), 74 deletions(-)

diff --git a/rust/kernel/auxiliary.rs b/rust/kernel/auxiliary.rs
index 93c0db1f66555..4a02f83240be3 100644
--- a/rust/kernel/auxiliary.rs
+++ b/rust/kernel/auxiliary.rs
@@ -63,7 +63,7 @@ unsafe fn register(
 
         // SAFETY: `adrv` is guaranteed to be a valid `DriverType`.
         to_result(unsafe {
-            bindings::__auxiliary_driver_register(adrv.get(), module.0, name.as_char_ptr())
+            bindings::__auxiliary_driver_register(adrv.get(), module.as_ptr(), name.as_char_ptr())
         })
     }
 
diff --git a/rust/kernel/i2c.rs b/rust/kernel/i2c.rs
index 7b908f0c5a58d..24eff08f47123 100644
--- a/rust/kernel/i2c.rs
+++ b/rust/kernel/i2c.rs
@@ -142,7 +142,7 @@ unsafe fn register(
         }
 
         // SAFETY: `idrv` is guaranteed to be a valid `DriverType`.
-        to_result(unsafe { bindings::i2c_register_driver(module.0, idrv.get()) })
+        to_result(unsafe { bindings::i2c_register_driver(module.as_ptr(), idrv.get()) })
     }
 
     unsafe fn unregister(idrv: &Opaque<Self::DriverType>) {
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index b72b2fbe046d6..040ae85056509 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -93,6 +93,7 @@
 pub mod maple_tree;
 pub mod miscdevice;
 pub mod mm;
+pub mod module;
 pub mod module_param;
 #[cfg(CONFIG_NET)]
 pub mod net;
@@ -139,79 +140,17 @@
 #[doc(hidden)]
 pub use bindings;
 pub use macros;
+pub use module::{
+    InPlaceModule,
+    Module,
+    ModuleMetadata,
+    ThisModule, //
+};
 pub use uapi;
 
 /// Prefix to appear before log messages printed from within the `kernel` crate.
 const __LOG_PREFIX: &[u8] = b"rust_kernel\0";
 
-/// The top level entrypoint to implementing a kernel module.
-///
-/// For any teardown or cleanup operations, your type may implement [`Drop`].
-pub trait Module: Sized + Sync + Send {
-    /// Called at module initialization time.
-    ///
-    /// Use this method to perform whatever setup or registration your module
-    /// should do.
-    ///
-    /// Equivalent to the `module_init` macro in the C API.
-    fn init(module: &'static ThisModule) -> error::Result<Self>;
-}
-
-/// A module that is pinned and initialised in-place.
-pub trait InPlaceModule: Sync + Send {
-    /// Creates an initialiser for the module.
-    ///
-    /// It is called when the module is loaded.
-    fn init(module: &'static ThisModule) -> impl pin_init::PinInit<Self, error::Error>;
-}
-
-impl<T: Module> InPlaceModule for T {
-    fn init(module: &'static ThisModule) -> impl pin_init::PinInit<Self, error::Error> {
-        let initer = move |slot: *mut Self| {
-            let m = <Self as Module>::init(module)?;
-
-            // SAFETY: `slot` is valid for write per the contract with `pin_init_from_closure`.
-            unsafe { slot.write(m) };
-            Ok(())
-        };
-
-        // SAFETY: On success, `initer` always fully initialises an instance of `Self`.
-        unsafe { pin_init::pin_init_from_closure(initer) }
-    }
-}
-
-/// Metadata attached to a [`Module`] or [`InPlaceModule`].
-pub trait ModuleMetadata {
-    /// The name of the module as specified in the `module!` macro.
-    const NAME: &'static crate::str::CStr;
-}
-
-/// Equivalent to `THIS_MODULE` in the C API.
-///
-/// C header: [`include/linux/init.h`](srctree/include/linux/init.h)
-pub struct ThisModule(*mut bindings::module);
-
-// SAFETY: `THIS_MODULE` may be used from all threads within a module.
-unsafe impl Sync for ThisModule {}
-
-impl ThisModule {
-    /// Creates a [`ThisModule`] given the `THIS_MODULE` pointer.
-    ///
-    /// # Safety
-    ///
-    /// The pointer must be equal to the right `THIS_MODULE`.
-    pub const unsafe fn from_ptr(ptr: *mut bindings::module) -> ThisModule {
-        ThisModule(ptr)
-    }
-
-    /// Access the raw pointer for this module.
-    ///
-    /// It is up to the user to use it correctly.
-    pub const fn as_ptr(&self) -> *mut bindings::module {
-        self.0
-    }
-}
-
 #[cfg(not(testlib))]
 #[panic_handler]
 fn panic(info: &core::panic::PanicInfo<'_>) -> ! {
diff --git a/rust/kernel/module.rs b/rust/kernel/module.rs
new file mode 100644
index 0000000000000..be242a82e86d2
--- /dev/null
+++ b/rust/kernel/module.rs
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Module-related types and helpers.
+
+/// The entrypoint to implementing a kernel module.
+///
+/// For any teardown or cleanup operations, your type may implement [`Drop`].
+pub trait Module: Sized + Sync + Send {
+    /// Called at module initialization time.
+    ///
+    /// Use this method to perform whatever setup or registration your module
+    /// should do.
+    ///
+    /// Equivalent to the `module_init` macro in the C API.
+    fn init(module: &'static ThisModule) -> crate::error::Result<Self>;
+}
+
+/// A module that is pinned and initialised in-place.
+pub trait InPlaceModule: Sync + Send {
+    /// Creates an initialiser for the module.
+    ///
+    /// It is called when the module is loaded.
+    fn init(module: &'static ThisModule) -> impl pin_init::PinInit<Self, crate::error::Error>;
+}
+
+impl<T: Module> InPlaceModule for T {
+    fn init(module: &'static ThisModule) -> impl pin_init::PinInit<Self, crate::error::Error> {
+        let initer = move |slot: *mut Self| {
+            let m = <Self as Module>::init(module)?;
+
+            // SAFETY: `slot` is valid for write per the contract with `pin_init_from_closure`.
+            unsafe { slot.write(m) };
+            Ok(())
+        };
+
+        // SAFETY: On success, `initer` always fully initialises an instance of `Self`.
+        unsafe { pin_init::pin_init_from_closure(initer) }
+    }
+}
+
+/// Metadata attached to a [`Module`] or [`InPlaceModule`].
+pub trait ModuleMetadata {
+    /// The name of the module as specified in the `module!` macro.
+    const NAME: &'static crate::str::CStr;
+}
+
+/// Equivalent to `THIS_MODULE` in the C API.
+///
+/// C header: [`include/linux/init.h`](srctree/include/linux/init.h)
+pub struct ThisModule(*mut crate::bindings::module);
+
+// SAFETY: `THIS_MODULE` may be used from all threads within a module.
+unsafe impl Sync for ThisModule {}
+
+impl ThisModule {
+    /// Creates a [`ThisModule`] given the `THIS_MODULE` pointer.
+    ///
+    /// # Safety
+    ///
+    /// The pointer must be equal to the right `THIS_MODULE`.
+    pub const unsafe fn from_ptr(ptr: *mut crate::bindings::module) -> ThisModule {
+        ThisModule(ptr)
+    }
+
+    /// Access the raw pointer for this module.
+    ///
+    /// It is up to the user to use it correctly.
+    pub const fn as_ptr(&self) -> *mut crate::bindings::module {
+        self.0
+    }
+}
diff --git a/rust/kernel/net/phy.rs b/rust/kernel/net/phy.rs
index 3ca99db5cccf2..8b7036b8fe480 100644
--- a/rust/kernel/net/phy.rs
+++ b/rust/kernel/net/phy.rs
@@ -659,7 +659,11 @@ pub fn register(
         // the `drivers` slice are initialized properly. `drivers` will not be moved.
         // So it's just an FFI call.
         to_result(unsafe {
-            bindings::phy_drivers_register(drivers[0].0.get(), drivers.len().try_into()?, module.0)
+            bindings::phy_drivers_register(
+                drivers[0].0.get(),
+                drivers.len().try_into()?,
+                module.as_ptr(),
+            )
         })?;
         // INVARIANT: The `drivers` slice is successfully registered to the kernel via `phy_drivers_register`.
         Ok(Registration { drivers })
diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index af74ddff6114d..916ed2cb6b70b 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -86,7 +86,7 @@ unsafe fn register(
 
         // SAFETY: `pdrv` is guaranteed to be a valid `DriverType`.
         to_result(unsafe {
-            bindings::__pci_register_driver(pdrv.get(), module.0, name.as_char_ptr())
+            bindings::__pci_register_driver(pdrv.get(), module.as_ptr(), name.as_char_ptr())
         })
     }
 
diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs
index 8917d4ee499fb..9fdbafd53bc21 100644
--- a/rust/kernel/platform.rs
+++ b/rust/kernel/platform.rs
@@ -82,7 +82,7 @@ unsafe fn register(
         }
 
         // SAFETY: `pdrv` is guaranteed to be a valid `DriverType`.
-        to_result(unsafe { bindings::__platform_driver_register(pdrv.get(), module.0) })
+        to_result(unsafe { bindings::__platform_driver_register(pdrv.get(), module.as_ptr()) })
     }
 
     unsafe fn unregister(pdrv: &Opaque<Self::DriverType>) {
diff --git a/rust/kernel/usb.rs b/rust/kernel/usb.rs
index 9c17a672cd275..213db32727c17 100644
--- a/rust/kernel/usb.rs
+++ b/rust/kernel/usb.rs
@@ -63,7 +63,7 @@ unsafe fn register(
 
         // SAFETY: `udrv` is guaranteed to be a valid `DriverType`.
         to_result(unsafe {
-            bindings::usb_register_driver(udrv.get(), module.0, name.as_char_ptr())
+            bindings::usb_register_driver(udrv.get(), module.as_ptr(), name.as_char_ptr())
         })
     }
 

-- 
2.43.0