Merge tag 'dd-lifetimes-7.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core into drm-rust-next

Higher-Ranked Lifetime Types for Rust device drivers

Replace drvdata() with registration data on the auxiliary bus. Private
data is now scoped to the registration object, removing the ordering
constraints and lifetime complications that came with drvdata().

Add Higher-Ranked Lifetime Types (HRT) so driver structs can borrow
device resources like pci::Bar and IoMem directly, tied to the device
binding scope. This removes the need for Devres indirection and
ARef<Device> in most driver code.

This is a stable tag for other trees to merge.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>

16 files changed, 690 insertions, 348 deletions

diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs
index bd6da02c7ab8..2f8c16473c2c 100644
--- a/rust/kernel/alloc/kbox.rs
+++ b/rust/kernel/alloc/kbox.rs
@@ -19,6 +19,7 @@ use crate::ffi::c_void;
 use crate::fmt;
 use crate::init::InPlaceInit;
 use crate::page::AsPageIter;
+use crate::prelude::*;
 use crate::types::ForeignOwnable;
 use pin_init::{InPlaceWrite, Init, PinInit, ZeroableOption};
 
@@ -256,6 +257,27 @@ where
         Ok(Box(ptr.cast(), PhantomData))
     }
 
+    /// Creates a new zero-initialized `Box<T, A>`.
+    ///
+    /// New memory is allocated with `A` and the [`__GFP_ZERO`] flag. The allocation may fail, in
+    /// which case an error is returned. For ZSTs no memory is allocated.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let b = KBox::<[u8; 128]>::zeroed(GFP_KERNEL)?;
+    /// assert_eq!(*b, [0; 128]);
+    /// # Ok::<(), Error>(())
+    /// ```
+    pub fn zeroed(flags: Flags) -> Result<Self, AllocError>
+    where
+        T: Zeroable,
+    {
+        // SAFETY: `__GFP_ZERO` guarantees the memory is zeroed; `T: Zeroable` guarantees that
+        // all-zeroes is a valid bit pattern for `T`.
+        Ok(unsafe { Self::new_uninit(flags | __GFP_ZERO)?.assume_init() })
+    }
+
     /// Constructs a new `Pin<Box<T, A>>`. If `T` does not implement [`Unpin`], then `x` will be
     /// pinned in memory and can't be moved.
     #[inline]
@@ -455,7 +477,7 @@ where
 
 // SAFETY: The pointer returned by `into_foreign` comes from a well aligned
 // pointer to `T` allocated by `A`.
-unsafe impl<T: 'static, A> ForeignOwnable for Box<T, A>
+unsafe impl<T, A> ForeignOwnable for Box<T, A>
 where
     A: Allocator,
 {
@@ -465,8 +487,14 @@ where
         core::mem::align_of::<T>()
     };
 
-    type Borrowed<'a> = &'a T;
-    type BorrowedMut<'a> = &'a mut T;
+    type Borrowed<'a>
+        = &'a T
+    where
+        Self: 'a;
+    type BorrowedMut<'a>
+        = &'a mut T
+    where
+        Self: 'a;
 
     fn into_foreign(self) -> *mut c_void {
         Box::into_raw(self).cast()
@@ -494,13 +522,19 @@ where
 
 // SAFETY: The pointer returned by `into_foreign` comes from a well aligned
 // pointer to `T` allocated by `A`.
-unsafe impl<T: 'static, A> ForeignOwnable for Pin<Box<T, A>>
+unsafe impl<T, A> ForeignOwnable for Pin<Box<T, A>>
 where
     A: Allocator,
 {
     const FOREIGN_ALIGN: usize = <Box<T, A> as ForeignOwnable>::FOREIGN_ALIGN;
-    type Borrowed<'a> = Pin<&'a T>;
-    type BorrowedMut<'a> = Pin<&'a mut T>;
+    type Borrowed<'a>
+        = Pin<&'a T>
+    where
+        Self: 'a;
+    type BorrowedMut<'a>
+        = Pin<&'a mut T>
+    where
+        Self: 'a;
 
     fn into_foreign(self) -> *mut c_void {
         // SAFETY: We are still treating the box as pinned.
diff --git a/rust/kernel/auxiliary.rs b/rust/kernel/auxiliary.rs
index 93c0db1f6655..c42928d5a239 100644
--- a/rust/kernel/auxiliary.rs
+++ b/rust/kernel/auxiliary.rs
@@ -12,19 +12,25 @@ use crate::{
         RawDeviceId,
         RawDeviceIdIndex, //
     },
-    devres::Devres,
+
     driver,
     error::{
         from_result,
         to_result, //
     },
     prelude::*,
-    types::Opaque,
+    types::{
+        ForLt,
+        ForeignOwnable,
+        Opaque, //
+    },
     ThisModule, //
 };
 use core::{
+    any::TypeId,
     marker::PhantomData,
     mem::offset_of,
+    pin::Pin,
     ptr::{
         addr_of_mut,
         NonNull, //
@@ -36,18 +42,18 @@ pub struct Adapter<T: Driver>(T);
 
 // SAFETY:
 // - `bindings::auxiliary_driver` is a C type declared as `repr(C)`.
-// - `T` is the type of the driver's device private data.
+// - `T::Data` is the type of the driver's device private data.
 // - `struct auxiliary_driver` embeds a `struct device_driver`.
 // - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
-unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
+unsafe impl<T: Driver> driver::DriverLayout for Adapter<T> {
     type DriverType = bindings::auxiliary_driver;
-    type DriverData = T;
+    type DriverData<'bound> = T::Data<'bound>;
     const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
 }
 
 // SAFETY: A call to `unregister` for a given instance of `DriverType` is guaranteed to be valid if
 // a preceding call to `register` has been successful.
-unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
+unsafe impl<T: Driver> driver::RegistrationOps for Adapter<T> {
     unsafe fn register(
         adrv: &Opaque<Self::DriverType>,
         name: &'static CStr,
@@ -73,7 +79,7 @@ unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
     }
 }
 
-impl<T: Driver + 'static> Adapter<T> {
+impl<T: Driver> Adapter<T> {
     extern "C" fn probe_callback(
         adev: *mut bindings::auxiliary_device,
         id: *const bindings::auxiliary_device_id,
@@ -82,7 +88,7 @@ impl<T: Driver + 'static> Adapter<T> {
         // `struct auxiliary_device`.
         //
         // INVARIANT: `adev` is valid for the duration of `probe_callback()`.
-        let adev = unsafe { &*adev.cast::<Device<device::CoreInternal>>() };
+        let adev = unsafe { &*adev.cast::<Device<device::CoreInternal<'_>>>() };
 
         // SAFETY: `DeviceId` is a `#[repr(transparent)`] wrapper of `struct auxiliary_device_id`
         // and does not add additional invariants, so it's safe to transmute.
@@ -102,12 +108,12 @@ impl<T: Driver + 'static> Adapter<T> {
         // `struct auxiliary_device`.
         //
         // INVARIANT: `adev` is valid for the duration of `remove_callback()`.
-        let adev = unsafe { &*adev.cast::<Device<device::CoreInternal>>() };
+        let adev = unsafe { &*adev.cast::<Device<device::CoreInternal<'_>>>() };
 
         // SAFETY: `remove_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
-        // and stored a `Pin<KBox<T>>`.
-        let data = unsafe { adev.as_ref().drvdata_borrow::<T>() };
+        // and stored a `Pin<KBox<T::Data<'_>>>`.
+        let data = unsafe { adev.as_ref().drvdata_borrow::<T::Data<'_>>() };
 
         T::unbind(adev, data);
     }
@@ -197,13 +203,19 @@ pub trait Driver {
     /// type IdInfo: 'static = ();
     type IdInfo: 'static;
 
+    /// The type of the driver's bus device private data.
+    type Data<'bound>: Send + 'bound;
+
     /// The table of device ids supported by the driver.
     const ID_TABLE: IdTable<Self::IdInfo>;
 
     /// Auxiliary driver probe.
     ///
     /// Called when an auxiliary device is matches a corresponding driver.
-    fn probe(dev: &Device<device::Core>, id_info: &Self::IdInfo) -> impl PinInit<Self, Error>;
+    fn probe<'bound>(
+        dev: &'bound Device<device::Core<'_>>,
+        id_info: &'bound Self::IdInfo,
+    ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound;
 
     /// Auxiliary driver unbind.
     ///
@@ -214,8 +226,8 @@ pub trait Driver {
     /// `&Device<Core>` or `&Device<Bound>` reference. For instance, drivers may try to perform I/O
     /// operations to gracefully tear down the device.
     ///
-    /// Otherwise, release operations for driver resources should be performed in `Self::drop`.
-    fn unbind(dev: &Device<device::Core>, this: Pin<&Self>) {
+    /// Otherwise, release operations for driver resources should be performed in `Drop`.
+    fn unbind<'bound>(dev: &'bound Device<device::Core<'_>>, this: Pin<&Self::Data<'bound>>) {
         let _ = (dev, this);
     }
 }
@@ -257,6 +269,49 @@ impl Device<device::Bound> {
         // SAFETY: A bound auxiliary device always has a bound parent device.
         unsafe { parent.as_bound() }
     }
+
+    /// Returns a pinned reference to the registration data set by the registering (parent) driver.
+    ///
+    /// `F` is the [`ForLt`](trait@ForLt) encoding of the data type. The returned
+    /// reference has its lifetime shortened from `'static` to `&self`'s borrow lifetime via
+    /// [`ForLt::cast_ref`].
+    ///
+    /// Returns [`EINVAL`] if `F` does not match the type used by the parent driver when calling
+    /// [`Registration::new()`].
+    ///
+    /// Returns [`ENOENT`] if no registration data has been set, e.g. when the device was
+    /// registered by a C driver.
+    pub fn registration_data<F: ForLt + 'static>(&self) -> Result<Pin<&F::Of<'_>>> {
+        // SAFETY: By the type invariant, `self.as_raw()` is a valid `struct auxiliary_device`.
+        let ptr = unsafe { (*self.as_raw()).registration_data_rust };
+        if ptr.is_null() {
+            dev_warn!(
+                self.as_ref(),
+                "No registration data set; parent is not a Rust driver.\n"
+            );
+            return Err(ENOENT);
+        }
+
+        // SAFETY: `ptr` is non-null and was set via `into_foreign()` in `Registration::new()`;
+        // `RegistrationData` is `#[repr(C)]` with `type_id` at offset 0, so reading a `TypeId`
+        // at the start of the allocation is valid regardless of `F`.
+        let type_id = unsafe { ptr.cast::<TypeId>().read() };
+        if type_id != TypeId::of::<F>() {
+            return Err(EINVAL);
+        }
+
+        // SAFETY: The `TypeId` check above confirms that the stored type matches
+        // `F::Of<'static>`; `ptr` remains valid until `Registration::drop()` calls
+        // `from_foreign()`.
+        let wrapper = unsafe { Pin::<KBox<RegistrationData<F::Of<'static>>>>::borrow(ptr) };
+
+        // SAFETY: `data` is a structurally pinned field of `RegistrationData`.
+        let pinned: Pin<&F::Of<'_>> = unsafe { wrapper.map_unchecked(|w| &w.data) };
+
+        // SAFETY: The data was pinned when stored; `cast_ref` only shortens
+        // the lifetime, so the pinning guarantee is preserved.
+        Ok(unsafe { Pin::new_unchecked(F::cast_ref(pinned.get_ref())) })
+    }
 }
 
 impl Device {
@@ -326,87 +381,173 @@ unsafe impl Send for Device {}
 // (i.e. `Device<Normal>) are thread safe.
 unsafe impl Sync for Device {}
 
+// SAFETY: Same as `Device<Normal>` -- the underlying `struct auxiliary_device` is the same;
+// `Bound` is a zero-sized type-state marker that does not affect thread safety.
+unsafe impl Sync for Device<device::Bound> {}
+
+/// Wrapper that stores a [`TypeId`] alongside the registration data for runtime type checking.
+#[repr(C)]
+#[pin_data]
+struct RegistrationData<T> {
+    type_id: TypeId,
+    #[pin]
+    data: T,
+}
+
 /// The registration of an auxiliary device.
 ///
 /// This type represents the registration of a [`struct auxiliary_device`]. When its parent device
 /// is unbound, the corresponding auxiliary device will be unregistered from the system.
 ///
+/// The type parameter `F` is a [`ForLt`](trait@ForLt) encoding of the registration
+/// data type. For non-lifetime-parameterized types, use [`ForLt!(T)`](macro@ForLt).
+/// The data can be accessed by the auxiliary driver through [`Device::registration_data()`].
+///
 /// # Invariants
 ///
-/// `self.0` always holds a valid pointer to an initialized and registered
-/// [`struct auxiliary_device`].
-pub struct Registration(NonNull<bindings::auxiliary_device>);
+/// `self.adev` always holds a valid pointer to an initialized and registered
+/// [`struct auxiliary_device`] whose `registration_data_rust` field points to a
+/// valid `Pin<KBox<RegistrationData<F::Of<'static>>>>`.
+pub struct Registration<'a, F: ForLt + 'static> {
+    adev: NonNull<bindings::auxiliary_device>,
+    _phantom: PhantomData<F::Of<'a>>,
+}
 
-impl Registration {
-    /// Create and register a new auxiliary device.
-    pub fn new<'a>(
+impl<'a, F: ForLt> Registration<'a, F>
+where
+    for<'b> F::Of<'b>: Send + Sync,
+{
+    /// Create and register a new auxiliary device with the given registration data.
+    ///
+    /// The `data` is owned by the registration and can be accessed through the auxiliary device
+    /// via [`Device::registration_data()`].
+    ///
+    /// # Safety
+    ///
+    /// The caller must not `mem::forget()` the returned [`Registration`] or otherwise prevent its
+    /// [`Drop`] implementation from running, since the registration data may contain borrowed
+    /// references that become invalid after `'a` ends.
+    ///
+    /// If the registration data is `'static`, use the safe [`Registration::new()`] instead.
+    pub unsafe fn new_with_lt<E>(
         parent: &'a device::Device<device::Bound>,
-        name: &'a CStr,
+        name: &CStr,
         id: u32,
-        modname: &'a CStr,
-    ) -> impl PinInit<Devres<Self>, Error> + 'a {
-        pin_init::pin_init_scope(move || {
-            let boxed = KBox::new(Opaque::<bindings::auxiliary_device>::zeroed(), GFP_KERNEL)?;
-            let adev = boxed.get();
-
-            // SAFETY: It's safe to set the fields of `struct auxiliary_device` on initialization.
-            unsafe {
-                (*adev).dev.parent = parent.as_raw();
-                (*adev).dev.release = Some(Device::release);
-                (*adev).name = name.as_char_ptr();
-                (*adev).id = id;
-            }
-
-            // SAFETY: `adev` is guaranteed to be a valid pointer to a `struct auxiliary_device`,
-            // which has not been initialized yet.
-            unsafe { bindings::auxiliary_device_init(adev) };
-
-            // Now that `adev` is initialized, leak the `Box`; the corresponding memory will be
-            // freed by `Device::release` when the last reference to the `struct auxiliary_device`
-            // is dropped.
-            let _ = KBox::into_raw(boxed);
-
-            // SAFETY:
-            // - `adev` is guaranteed to be a valid pointer to a `struct auxiliary_device`, which
-            //   has been initialized,
-            // - `modname.as_char_ptr()` is a NULL terminated string.
-            let ret = unsafe { bindings::__auxiliary_device_add(adev, modname.as_char_ptr()) };
-            if ret != 0 {
-                // SAFETY: `adev` is guaranteed to be a valid pointer to a
-                // `struct auxiliary_device`, which has been initialized.
-                unsafe { bindings::auxiliary_device_uninit(adev) };
-
-                return Err(Error::from_errno(ret));
-            }
-
-            // INVARIANT: The device will remain registered until `auxiliary_device_delete()` is
-            // called, which happens in `Self::drop()`.
-            Ok(Devres::new(
-                parent,
-                // SAFETY: `adev` is guaranteed to be non-null, since the `KBox` was allocated
-                // successfully.
-                Self(unsafe { NonNull::new_unchecked(adev) }),
-            ))
+        modname: &CStr,
+        data: impl PinInit<F::Of<'a>, E>,
+    ) -> Result<Self>
+    where
+        Error: From<E>,
+    {
+        let data = KBox::pin_init::<Error>(
+            try_pin_init!(RegistrationData {
+                type_id: TypeId::of::<F>(),
+                data <- data,
+            }),
+            GFP_KERNEL,
+        )?;
+
+        // SAFETY: `'a` is invariant (via `Registration`'s `PhantomData`). Lifetimes do not
+        // affect layout, so RegistrationData<F::Of<'a>> and RegistrationData<F::Of<'static>>
+        // have identical representation.
+        let data: Pin<KBox<RegistrationData<F::Of<'static>>>> =
+            unsafe { core::mem::transmute(data) };
+
+        let boxed: KBox<Opaque<bindings::auxiliary_device>> = KBox::zeroed(GFP_KERNEL)?;
+        let adev = boxed.get();
+
+        // SAFETY: It's safe to set the fields of `struct auxiliary_device` on initialization.
+        unsafe {
+            (*adev).dev.parent = parent.as_raw();
+            (*adev).dev.release = Some(Device::release);
+            (*adev).name = name.as_char_ptr();
+            (*adev).id = id;
+            (*adev).registration_data_rust = data.into_foreign();
+        }
+
+        // SAFETY: `adev` is guaranteed to be a valid pointer to a `struct auxiliary_device`,
+        // which has not been initialized yet.
+        unsafe { bindings::auxiliary_device_init(adev) };
+
+        // Now that `adev` is initialized, leak the `Box`; the corresponding memory will be
+        // freed by `Device::release` when the last reference to the `struct auxiliary_device`
+        // is dropped.
+        let _ = KBox::into_raw(boxed);
+
+        // SAFETY:
+        // - `adev` is guaranteed to be a valid pointer to a `struct auxiliary_device`, which
+        //   has been initialized,
+        // - `modname.as_char_ptr()` is a NULL terminated string.
+        let ret = unsafe { bindings::__auxiliary_device_add(adev, modname.as_char_ptr()) };
+        if ret != 0 {
+            // SAFETY: `registration_data` was set above via `into_foreign()`.
+            drop(unsafe {
+                Pin::<KBox<RegistrationData<F::Of<'static>>>>::from_foreign(
+                    (*adev).registration_data_rust,
+                )
+            });
+
+            // SAFETY: `adev` is guaranteed to be a valid pointer to a
+            // `struct auxiliary_device`, which has been initialized.
+            unsafe { bindings::auxiliary_device_uninit(adev) };
+
+            return Err(Error::from_errno(ret));
+        }
+
+        // INVARIANT: The device will remain registered until `auxiliary_device_delete()` is
+        // called, which happens in `Self::drop()`.
+        Ok(Self {
+            // SAFETY: `adev` is guaranteed to be non-null, since the `KBox` was allocated
+            // successfully.
+            adev: unsafe { NonNull::new_unchecked(adev) },
+            _phantom: PhantomData,
         })
     }
+
+    /// Create and register a new auxiliary device with `'static` registration data.
+    ///
+    /// Safe variant of [`Registration::new_with_lt()`] for registration data that does not contain
+    /// borrowed references.
+    pub fn new<E>(
+        parent: &'a device::Device<device::Bound>,
+        name: &CStr,
+        id: u32,
+        modname: &CStr,
+        data: impl PinInit<F::Of<'a>, E>,
+    ) -> Result<Self>
+    where
+        F::Of<'a>: 'static,
+        Error: From<E>,
+    {
+        // SAFETY: `F::Of<'a>: 'static` guarantees the data contains no borrowed references,
+        // so forgetting the `Registration` cannot cause use-after-free.
+        unsafe { Self::new_with_lt(parent, name, id, modname, data) }
+    }
 }
 
-impl Drop for Registration {
+impl<F: ForLt> Drop for Registration<'_, F> {
     fn drop(&mut self) {
-        // SAFETY: By the type invariant of `Self`, `self.0.as_ptr()` is a valid registered
+        // SAFETY: By the type invariant of `Self`, `self.adev.as_ptr()` is a valid registered
         // `struct auxiliary_device`.
-        unsafe { bindings::auxiliary_device_delete(self.0.as_ptr()) };
+        unsafe { bindings::auxiliary_device_delete(self.adev.as_ptr()) };
+
+        // SAFETY: `registration_data` was set in `new()` via `into_foreign()`.
+        drop(unsafe {
+            Pin::<KBox<RegistrationData<F::Of<'static>>>>::from_foreign(
+                (*self.adev.as_ptr()).registration_data_rust,
+            )
+        });
 
         // This drops the reference we acquired through `auxiliary_device_init()`.
         //
-        // SAFETY: By the type invariant of `Self`, `self.0.as_ptr()` is a valid registered
+        // SAFETY: By the type invariant of `Self`, `self.adev.as_ptr()` is a valid registered
         // `struct auxiliary_device`.
-        unsafe { bindings::auxiliary_device_uninit(self.0.as_ptr()) };
+        unsafe { bindings::auxiliary_device_uninit(self.adev.as_ptr()) };
     }
 }
 
 // SAFETY: A `Registration` of a `struct auxiliary_device` can be released from any thread.
-unsafe impl Send for Registration {}
+unsafe impl<F: ForLt> Send for Registration<'_, F> where for<'a> F::Of<'a>: Send {}
 
 // SAFETY: `Registration` does not expose any methods or fields that need synchronization.
-unsafe impl Sync for Registration {}
+unsafe impl<F: ForLt> Sync for Registration<'_, F> where for<'a> F::Of<'a>: Send {}
diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
index d8d26870bea2..d94c6cdbc45a 100644
--- a/rust/kernel/cpufreq.rs
+++ b/rust/kernel/cpufreq.rs
@@ -888,12 +888,13 @@ pub trait Driver {
 ///
 /// impl platform::Driver for SampleDriver {
 ///     type IdInfo = ();
+///     type Data<'bound> = Self;
 ///     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;
 ///
-///     fn probe(
-///         pdev: &platform::Device<Core>,
-///         _id_info: Option<&Self::IdInfo>,
-///     ) -> impl PinInit<Self, Error> {
+///     fn probe<'bound>(
+///         pdev: &'bound platform::Device<Core<'_>>,
+///         _id_info: Option<&'bound Self::IdInfo>,
+///     ) -> impl PinInit<Self, Error> + 'bound {
 ///         cpufreq::Registration::<SampleDriver>::new_foreign_owned(pdev.as_ref())?;
 ///         Ok(Self {})
 ///     }
diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs
index 6d5396a43ebe..645afc49a27d 100644
--- a/rust/kernel/device.rs
+++ b/rust/kernel/device.rs
@@ -15,16 +15,12 @@ use crate::{
     }, //
 };
 use core::{
-    any::TypeId,
     marker::PhantomData,
     ptr, //
 };
 
 pub mod property;
 
-// Assert that we can `read()` / `write()` a `TypeId` instance from / into `struct driver_type`.
-static_assert!(core::mem::size_of::<bindings::driver_type>() >= core::mem::size_of::<TypeId>());
-
 /// The core representation of a device in the kernel's driver model.
 ///
 /// This structure represents the Rust abstraction for a C `struct device`. A [`Device`] can either
@@ -205,30 +201,13 @@ impl Device {
     }
 }
 
-impl Device<CoreInternal> {
-    fn set_type_id<T: 'static>(&self) {
-        // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`.
-        let private = unsafe { (*self.as_raw()).p };
-
-        // SAFETY: For a bound device (implied by the `CoreInternal` device context), `private` is
-        // guaranteed to be a valid pointer to a `struct device_private`.
-        let driver_type = unsafe { &raw mut (*private).driver_type };
-
-        // SAFETY: `driver_type` is valid for (unaligned) writes of a `TypeId`.
-        unsafe {
-            driver_type
-                .cast::<TypeId>()
-                .write_unaligned(TypeId::of::<T>())
-        };
-    }
-
+impl<'a> Device<CoreInternal<'a>> {
     /// Store a pointer to the bound driver's private data.
-    pub fn set_drvdata<T: 'static>(&self, data: impl PinInit<T, Error>) -> Result {
+    pub fn set_drvdata<T>(&self, data: impl PinInit<T, Error>) -> Result {
         let data = KBox::pin_init(data, GFP_KERNEL)?;
 
         // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`.
         unsafe { bindings::dev_set_drvdata(self.as_raw(), data.into_foreign().cast()) };
-        self.set_type_id::<T>();
 
         Ok(())
     }
@@ -239,7 +218,7 @@ impl Device<CoreInternal> {
     ///
     /// - The type `T` must match the type of the `ForeignOwnable` previously stored by
     ///   [`Device::set_drvdata`].
-    pub(crate) unsafe fn drvdata_obtain<T: 'static>(&self) -> Option<Pin<KBox<T>>> {
+    pub(crate) unsafe fn drvdata_obtain<T>(&self) -> Option<Pin<KBox<T>>> {
         // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`.
         let ptr = unsafe { bindings::dev_get_drvdata(self.as_raw()) };
 
@@ -265,7 +244,7 @@ impl Device<CoreInternal> {
     ///   device is fully unbound.
     /// - The type `T` must match the type of the `ForeignOwnable` previously stored by
     ///   [`Device::set_drvdata`].
-    pub unsafe fn drvdata_borrow<T: 'static>(&self) -> Pin<&T> {
+    pub unsafe fn drvdata_borrow<T>(&self) -> Pin<&T> {
         // SAFETY: `drvdata_unchecked()` has the exact same safety requirements as the ones
         // required by this method.
         unsafe { self.drvdata_unchecked() }
@@ -281,7 +260,7 @@ impl Device<Bound> {
     ///   the device is fully unbound.
     /// - The type `T` must match the type of the `ForeignOwnable` previously stored by
     ///   [`Device::set_drvdata`].
-    unsafe fn drvdata_unchecked<T: 'static>(&self) -> Pin<&T> {
+    unsafe fn drvdata_unchecked<T>(&self) -> Pin<&T> {
         // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`.
         let ptr = unsafe { bindings::dev_get_drvdata(self.as_raw()) };
 
@@ -292,45 +271,6 @@ impl Device<Bound> {
         //   in `into_foreign()`.
         unsafe { Pin::<KBox<T>>::borrow(ptr.cast()) }
     }
-
-    fn match_type_id<T: 'static>(&self) -> Result {
-        // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`.
-        let private = unsafe { (*self.as_raw()).p };
-
-        // SAFETY: For a bound device, `private` is guaranteed to be a valid pointer to a
-        // `struct device_private`.
-        let driver_type = unsafe { &raw mut (*private).driver_type };
-
-        // SAFETY:
-        // - `driver_type` is valid for (unaligned) reads of a `TypeId`.
-        // - A bound device guarantees that `driver_type` contains a valid `TypeId` value.
-        let type_id = unsafe { driver_type.cast::<TypeId>().read_unaligned() };
-
-        if type_id != TypeId::of::<T>() {
-            return Err(EINVAL);
-        }
-
-        Ok(())
-    }
-
-    /// Access a driver's private data.
-    ///
-    /// Returns a pinned reference to the driver's private data or [`EINVAL`] if it doesn't match
-    /// the asserted type `T`.
-    pub fn drvdata<T: 'static>(&self) -> Result<Pin<&T>> {
-        // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`.
-        if unsafe { bindings::dev_get_drvdata(self.as_raw()) }.is_null() {
-            return Err(ENOENT);
-        }
-
-        self.match_type_id::<T>()?;
-
-        // SAFETY:
-        // - The above check of `dev_get_drvdata()` guarantees that we are called after
-        //   `set_drvdata()`.
-        // - We've just checked that the type of the driver's private data is in fact `T`.
-        Ok(unsafe { self.drvdata_unchecked() })
-    }
 }
 
 impl<Ctx: DeviceContext> Device<Ctx> {
@@ -527,6 +467,10 @@ unsafe impl Send for Device {}
 // synchronization in `struct device`.
 unsafe impl Sync for Device {}
 
+// SAFETY: Same as `Device<Normal>` -- the underlying `struct device` is the same; `Bound` is a
+// zero-sized type-state marker that does not affect thread safety.
+unsafe impl Sync for Device<Bound> {}
+
 /// Marker trait for the context or scope of a bus specific device.
 ///
 /// [`DeviceContext`] is a marker trait for types representing the context of a bus specific
@@ -567,7 +511,7 @@ pub struct Normal;
 /// callback it appears in. It is intended to be used for synchronization purposes. Bus device
 /// implementations can implement methods for [`Device<Core>`], such that they can only be called
 /// from bus callbacks.
-pub struct Core;
+pub struct Core<'a>(PhantomData<&'a ()>);
 
 /// Semantically the same as [`Core`], but reserved for internal usage of the corresponding bus
 /// abstraction.
@@ -578,7 +522,7 @@ pub struct Core;
 ///
 /// This context mainly exists to share generic [`Device`] infrastructure that should only be called
 /// from bus callbacks with bus abstractions, but without making them accessible for drivers.
-pub struct CoreInternal;
+pub struct CoreInternal<'a>(PhantomData<&'a ()>);
 
 /// The [`Bound`] context is the [`DeviceContext`] of a bus specific device when it is guaranteed to
 /// be bound to a driver.
@@ -602,14 +546,14 @@ mod private {
     pub trait Sealed {}
 
     impl Sealed for super::Bound {}
-    impl Sealed for super::Core {}
-    impl Sealed for super::CoreInternal {}
+    impl<'a> Sealed for super::Core<'a> {}
+    impl<'a> Sealed for super::CoreInternal<'a> {}
     impl Sealed for super::Normal {}
 }
 
 impl DeviceContext for Bound {}
-impl DeviceContext for Core {}
-impl DeviceContext for CoreInternal {}
+impl<'a> DeviceContext for Core<'a> {}
+impl<'a> DeviceContext for CoreInternal<'a> {}
 impl DeviceContext for Normal {}
 
 impl<Ctx: DeviceContext> AsRef<Device<Ctx>> for Device<Ctx> {
@@ -659,6 +603,22 @@ pub unsafe trait AsBusDevice<Ctx: DeviceContext>: AsRef<Device<Ctx>> {
 #[doc(hidden)]
 #[macro_export]
 macro_rules! __impl_device_context_deref {
+    (unsafe { $device:ident, <$lt:lifetime> $src:ty => $dst:ty }) => {
+        impl<$lt> ::core::ops::Deref for $device<$src> {
+            type Target = $device<$dst>;
+
+            fn deref(&self) -> &Self::Target {
+                let ptr: *const Self = self;
+
+                // CAST: `$device<$src>` and `$device<$dst>` transparently wrap the same type by the
+                // safety requirement of the macro.
+                let ptr = ptr.cast::<Self::Target>();
+
+                // SAFETY: `ptr` was derived from `&self`.
+                unsafe { &*ptr }
+            }
+        }
+    };
     (unsafe { $device:ident, $src:ty => $dst:ty }) => {
         impl ::core::ops::Deref for $device<$src> {
             type Target = $device<$dst>;
@@ -691,14 +651,14 @@ macro_rules! impl_device_context_deref {
         // `__impl_device_context_deref!`.
         ::kernel::__impl_device_context_deref!(unsafe {
             $device,
-            $crate::device::CoreInternal => $crate::device::Core
+            <'a> $crate::device::CoreInternal<'a> => $crate::device::Core<'a>
         });
 
         // SAFETY: This macro has the exact same safety requirement as
         // `__impl_device_context_deref!`.
         ::kernel::__impl_device_context_deref!(unsafe {
             $device,
-            $crate::device::Core => $crate::device::Bound
+            <'a> $crate::device::Core<'a> => $crate::device::Bound
         });
 
         // SAFETY: This macro has the exact same safety requirement as
@@ -713,6 +673,13 @@ macro_rules! impl_device_context_deref {
 #[doc(hidden)]
 #[macro_export]
 macro_rules! __impl_device_context_into_aref {
+    (<$lt:lifetime> $src:ty, $device:tt) => {
+        impl<$lt> ::core::convert::From<&$device<$src>> for $crate::sync::aref::ARef<$device> {
+            fn from(dev: &$device<$src>) -> Self {
+                (&**dev).into()
+            }
+        }
+    };
     ($src:ty, $device:tt) => {
         impl ::core::convert::From<&$device<$src>> for $crate::sync::aref::ARef<$device> {
             fn from(dev: &$device<$src>) -> Self {
@@ -727,8 +694,12 @@ macro_rules! __impl_device_context_into_aref {
 #[macro_export]
 macro_rules! impl_device_context_into_aref {
     ($device:tt) => {
-        ::kernel::__impl_device_context_into_aref!($crate::device::CoreInternal, $device);
-        ::kernel::__impl_device_context_into_aref!($crate::device::Core, $device);
+        ::kernel::__impl_device_context_into_aref!(
+            <'a> $crate::device::CoreInternal<'a>, $device
+        );
+        ::kernel::__impl_device_context_into_aref!(
+            <'a> $crate::device::Core<'a>, $device
+        );
         ::kernel::__impl_device_context_into_aref!($crate::device::Bound, $device);
     };
 }
diff --git a/rust/kernel/devres.rs b/rust/kernel/devres.rs
index 9e5f93aed20c..82cbd8b969fb 100644
--- a/rust/kernel/devres.rs
+++ b/rust/kernel/