Merge tag 'rust-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux

Pull Rust updates from Miguel Ojeda:
 "Toolchain and infrastructure:

   - Enable a set of Clippy lints: 'ptr_as_ptr', 'ptr_cast_constness',
     'as_ptr_cast_mut', 'as_underscore', 'cast_lossless' and
     'ref_as_ptr'

     These are intended to avoid type casts with the 'as' operator,
     which are quite powerful, into restricted variants that are less
     powerful and thus should help to avoid mistakes

   - Remove the 'author' key now that most instances were moved to the
     plural one in the previous cycle

  'kernel' crate:

   - New 'bug' module: add 'warn_on!' macro which reuses the existing
     'BUG'/'WARN' infrastructure, i.e. it respects the usual sysctls and
     kernel parameters:

         warn_on!(value == 42);

     To avoid duplicating the assembly code, the same strategy is
     followed as for the static branch code in order to share the
     assembly between both C and Rust

     This required a few rearrangements on C arch headers -- the
     existing C macros should still generate the same outputs, thus no
     functional change expected there

   - 'workqueue' module: add delayed work items, including a
     'DelayedWork' struct, a 'impl_has_delayed_work!' macro and an
     'enqueue_delayed' method, e.g.:

         /// Enqueue the struct for execution on the system workqueue,
         /// where its value will be printed 42 jiffies later.
         fn print_later(value: Arc<MyStruct>) {
             let _ = workqueue::system().enqueue_delayed(value, 42);
         }

   - New 'bits' module: add support for 'bit' and 'genmask' functions,
     with runtime- and compile-time variants, e.g.:

         static_assert!(0b00010000 == bit_u8(4));
         static_assert!(0b00011110 == genmask_u8(1..=4));

         assert!(checked_bit_u32(u32::BITS).is_none());

   - 'uaccess' module: add 'UserSliceReader::strcpy_into_buf', which
     reads NUL-terminated strings from userspace into a '&CStr'

     Introduce 'UserPtr' newtype, similar in purpose to '__user' in C,
     to minimize mistakes handling userspace pointers, including mixing
     them up with integers and leaking them via the 'Debug' trait. Add
     it to the prelude, too

   - Start preparations for the replacement of our custom 'CStr' type
     with the analogous type in the 'core' standard library. This will
     take place across several cycles to make it easier. For this one,
     it includes a new 'fmt' module, using upstream method names and
     some other cleanups

     Replace 'fmt!' with a re-export, which helps Clippy lint properly,
     and clean up the found 'uninlined-format-args' instances

   - 'dma' module:

      - Clarify wording and be consistent in 'coherent' nomenclature

      - Convert the 'read!()' and 'write!()' macros to return a 'Result'

      - Add 'as_slice()', 'write()' methods in 'CoherentAllocation'

      - Expose 'count()' and 'size()' in 'CoherentAllocation' and add
        the corresponding type invariants

      - Implement 'CoherentAllocation::dma_handle_with_offset()'

   - 'time' module:

      - Make 'Instant' generic over clock source. This allows the
        compiler to assert that arithmetic expressions involving the
        'Instant' use 'Instants' based on the same clock source

      - Make 'HrTimer' generic over the timer mode. 'HrTimer' timers
        take a 'Duration' or an 'Instant' when setting the expiry time,
        depending on the timer mode. With this change, the compiler can
        check the type matches the timer mode

      - Add an abstraction for 'fsleep'. 'fsleep' is a flexible sleep
        function that will select an appropriate sleep method depending
        on the requested sleep time

      - Avoid 64-bit divisions on 32-bit hardware when calculating
        timestamps

      - Seal the 'HrTimerMode' trait. This prevents users of the
        'HrTimerMode' from implementing the trait on their own types

      - Pass the correct timer mode ID to 'hrtimer_start_range_ns()'

   - 'list' module: remove 'OFFSET' constants, allowing to remove
     pointer arithmetic; now 'impl_list_item!' invokes
     'impl_has_list_links!' or 'impl_has_list_links_self_ptr!'. Other
     simplifications too

   - 'types' module: remove 'ForeignOwnable::PointedTo' in favor of a
     constant, which avoids exposing the type of the opaque pointer, and
     require 'into_foreign' to return non-null

     Remove the 'Either<L, R>' type as well. It is unused, and we want
     to encourage the use of custom enums for concrete use cases

   - 'sync' module: implement 'Borrow' and 'BorrowMut' for 'Arc' types
     to allow them to be used in generic APIs

   - 'alloc' module: implement 'Borrow' and 'BorrowMut' for 'Box<T, A>';
     and 'Borrow', 'BorrowMut' and 'Default' for 'Vec<T, A>'

   - 'Opaque' type: add 'cast_from' method to perform a restricted cast
     that cannot change the inner type and use it in callers of
     'container_of!'. Rename 'raw_get' to 'cast_into' to match it

   - 'rbtree' module: add 'is_empty' method

   - 'sync' module: new 'aref' submodule to hold 'AlwaysRefCounted' and
     'ARef', which are moved from the too general 'types' module which
     we want to reduce or eventually remove. Also fix a safety comment
     in 'static_lock_class'

  'pin-init' crate:

   - Add 'impl<T, E> [Pin]Init<T, E> for Result<T, E>', so results are
     now (pin-)initializers

   - Add 'Zeroable::init_zeroed()' that delegates to 'init_zeroed()'

   - New 'zeroed()', a safe version of 'mem::zeroed()' and also provide
     it via 'Zeroable::zeroed()'

   - Implement 'Zeroable' for 'Option<&T>', 'Option<&mut T>' and for
     'Option<[unsafe] [extern "abi"] fn(...args...) -> ret>' for
     '"Rust"' and '"C"' ABIs and up to 20 arguments

   - Changed blanket impls of 'Init' and 'PinInit' from 'impl<T, E>
     [Pin]Init<T, E> for T' to 'impl<T> [Pin]Init<T> for T'

   - Renamed 'zeroed()' to 'init_zeroed()'

   - Upstream dev news: improve CI more to deny warnings, use
     '--all-targets'. Check the synchronization status of the two
     '-next' branches in upstream and the kernel

  MAINTAINERS:

   - Add Vlastimil Babka, Liam R. Howlett, Uladzislau Rezki and Lorenzo
     Stoakes as reviewers (thanks everyone)

  And a few other cleanups and improvements"

* tag 'rust-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux: (76 commits)
  rust: Add warn_on macro
  arm64/bug: Add ARCH_WARN_ASM macro for BUG/WARN asm code sharing with Rust
  riscv/bug: Add ARCH_WARN_ASM macro for BUG/WARN asm code sharing with Rust
  x86/bug: Add ARCH_WARN_ASM macro for BUG/WARN asm code sharing with Rust
  rust: kernel: move ARef and AlwaysRefCounted to sync::aref
  rust: sync: fix safety comment for `static_lock_class`
  rust: types: remove `Either<L, R>`
  rust: kernel: use `core::ffi::CStr` method names
  rust: str: add `CStr` methods matching `core::ffi::CStr`
  rust: str: remove unnecessary qualification
  rust: use `kernel::{fmt,prelude::fmt!}`
  rust: kernel: add `fmt` module
  rust: kernel: remove `fmt!`, fix clippy::uninlined-format-args
  scripts: rust: emit path candidates in panic message
  scripts: rust: replace length checks with match
  rust: list: remove nonexistent generic parameter in link
  rust: bits: add support for bits/genmask macros
  rust: list: remove OFFSET constants
  rust: list: add `impl_list_item!` examples
  rust: list: use fully qualified path
  ...

6 files changed, 279 insertions, 110 deletions

diff --git a/rust/kernel/time/delay.rs b/rust/kernel/time/delay.rs
new file mode 100644
index 000000000000..eb8838da62bc
--- /dev/null
+++ b/rust/kernel/time/delay.rs
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Delay and sleep primitives.
+//!
+//! This module contains the kernel APIs related to delay and sleep that
+//! have been ported or wrapped for usage by Rust code in the kernel.
+//!
+//! C header: [`include/linux/delay.h`](srctree/include/linux/delay.h).
+
+use super::Delta;
+use crate::prelude::*;
+
+/// Sleeps for a given duration at least.
+///
+/// Equivalent to the C side [`fsleep()`], flexible sleep function,
+/// which automatically chooses the best sleep method based on a duration.
+///
+/// `delta` must be within `[0, i32::MAX]` microseconds;
+/// otherwise, it is erroneous behavior. That is, it is considered a bug
+/// to call this function with an out-of-range value, in which case the function
+/// will sleep for at least the maximum value in the range and may warn
+/// in the future.
+///
+/// The behavior above differs from the C side [`fsleep()`] for which out-of-range
+/// values mean "infinite timeout" instead.
+///
+/// This function can only be used in a nonatomic context.
+///
+/// [`fsleep()`]: https://docs.kernel.org/timers/delay_sleep_functions.html#c.fsleep
+pub fn fsleep(delta: Delta) {
+    // The maximum value is set to `i32::MAX` microseconds to prevent integer
+    // overflow inside fsleep, which could lead to unintentional infinite sleep.
+    const MAX_DELTA: Delta = Delta::from_micros(i32::MAX as i64);
+
+    let delta = if (Delta::ZERO..=MAX_DELTA).contains(&delta) {
+        delta
+    } else {
+        // TODO: Add WARN_ONCE() when it's supported.
+        MAX_DELTA
+    };
+
+    // SAFETY: It is always safe to call `fsleep()` with any duration.
+    unsafe {
+        // Convert the duration to microseconds and round up to preserve
+        // the guarantee; `fsleep()` sleeps for at least the provided duration,
+        // but that it may sleep for longer under some circumstances.
+        bindings::fsleep(delta.as_micros_ceil() as c_ulong)
+    }
+}
diff --git a/rust/kernel/time/hrtimer.rs b/rust/kernel/time/hrtimer.rs
index 36e1290cd079..144e3b57cc78 100644
--- a/rust/kernel/time/hrtimer.rs
+++ b/rust/kernel/time/hrtimer.rs
@@ -67,27 +67,11 @@
 //! A `restart` operation on a timer in the **stopped** state is equivalent to a
 //! `start` operation.
 
-use super::ClockId;
+use super::{ClockSource, Delta, Instant};
 use crate::{prelude::*, types::Opaque};
 use core::marker::PhantomData;
 use pin_init::PinInit;
 
-/// A Rust wrapper around a `ktime_t`.
-// NOTE: Ktime is going to be removed when hrtimer is converted to Instant/Delta.
-#[repr(transparent)]
-#[derive(Copy, Clone, PartialEq, PartialOrd, Eq, Ord)]
-pub struct Ktime {
-    inner: bindings::ktime_t,
-}
-
-impl Ktime {
-    /// Returns the number of nanoseconds.
-    #[inline]
-    pub fn to_ns(self) -> i64 {
-        self.inner
-    }
-}
-
 /// A timer backed by a C `struct hrtimer`.
 ///
 /// # Invariants
@@ -98,7 +82,6 @@ impl Ktime {
 pub struct HrTimer<T> {
     #[pin]
     timer: Opaque<bindings::hrtimer>,
-    mode: HrTimerMode,
     _t: PhantomData<T>,
 }
 
@@ -112,9 +95,10 @@ unsafe impl<T> Sync for HrTimer<T> {}
 
 impl<T> HrTimer<T> {
     /// Return an initializer for a new timer instance.
-    pub fn new(mode: HrTimerMode, clock: ClockId) -> impl PinInit<Self>
+    pub fn new() -> impl PinInit<Self>
     where
         T: HrTimerCallback,
+        T: HasHrTimer<T>,
     {
         pin_init!(Self {
             // INVARIANT: We initialize `timer` with `hrtimer_setup` below.
@@ -126,12 +110,11 @@ impl<T> HrTimer<T> {
                     bindings::hrtimer_setup(
                         place,
                         Some(T::Pointer::run),
-                        clock.into_c(),
-                        mode.into_c(),
+                        <<T as HasHrTimer<T>>::TimerMode as HrTimerMode>::Clock::ID,
+                        <T as HasHrTimer<T>>::TimerMode::C_MODE,
                     );
                 }
             }),
-            mode: mode,
             _t: PhantomData,
         })
     }
@@ -148,7 +131,7 @@ impl<T> HrTimer<T> {
         // SAFETY: The field projection to `timer` does not go out of bounds,
         // because the caller of this function promises that `this` points to an
         // allocation of at least the size of `Self`.
-        unsafe { Opaque::raw_get(core::ptr::addr_of!((*this).timer)) }
+        unsafe { Opaque::cast_into(core::ptr::addr_of!((*this).timer)) }
     }
 
     /// Cancel an initialized and potentially running timer.
@@ -193,6 +176,11 @@ impl<T> HrTimer<T> {
 /// exist. A timer can be manipulated through any of the handles, and a handle
 /// may represent a cancelled timer.
 pub trait HrTimerPointer: Sync + Sized {
+    /// The operational mode associated with this timer.
+    ///
+    /// This defines how the expiration value is interpreted.
+    type TimerMode: HrTimerMode;
+
     /// A handle representing a started or restarted timer.
     ///
     /// If the timer is running or if the timer callback is executing when the
@@ -205,7 +193,7 @@ pub trait HrTimerPointer: Sync + Sized {
 
     /// Start the timer with expiry after `expires` time units. If the timer was
     /// already running, it is restarted with the new expiry time.
-    fn start(self, expires: Ktime) -> Self::TimerHandle;
+    fn start(self, expires: <Self::TimerMode as HrTimerMode>::Expires) -> Self::TimerHandle;
 }
 
 /// Unsafe version of [`HrTimerPointer`] for situations where leaking the
@@ -220,6 +208,11 @@ pub trait HrTimerPointer: Sync + Sized {
 /// [`UnsafeHrTimerPointer`] outlives any associated [`HrTimerPointer::TimerHandle`]
 /// instances.
 pub unsafe trait UnsafeHrTimerPointer: Sync + Sized {
+    /// The operational mode associated with this timer.
+    ///
+    /// This defines how the expiration value is interpreted.
+    type TimerMode: HrTimerMode;
+
     /// A handle representing a running timer.
     ///
     /// # Safety
@@ -236,7 +229,7 @@ pub unsafe trait UnsafeHrTimerPointer: Sync + Sized {
     ///
     /// Caller promises keep the timer structure alive until the timer is dead.
     /// Caller can ensure this by not leaking the returned [`Self::TimerHandle`].
-    unsafe fn start(self, expires: Ktime) -> Self::TimerHandle;
+    unsafe fn start(self, expires: <Self::TimerMode as HrTimerMode>::Expires) -> Self::TimerHandle;
 }
 
 /// A trait for stack allocated timers.
@@ -246,9 +239,14 @@ pub unsafe trait UnsafeHrTimerPointer: Sync + Sized {
 /// Implementers must ensure that `start_scoped` does not return until the
 /// timer is dead and the timer handler is not running.
 pub unsafe trait ScopedHrTimerPointer {
+    /// The operational mode associated with this timer.
+    ///
+    /// This defines how the expiration value is interpreted.
+    type TimerMode: HrTimerMode;
+
     /// Start the timer to run after `expires` time units and immediately
     /// after call `f`. When `f` returns, the timer is cancelled.
-    fn start_scoped<T, F>(self, expires: Ktime, f: F) -> T
+    fn start_scoped<T, F>(self, expires: <Self::TimerMode as HrTimerMode>::Expires, f: F) -> T
     where
         F: FnOnce() -> T;
 }
@@ -260,7 +258,13 @@ unsafe impl<T> ScopedHrTimerPointer for T
 where
     T: UnsafeHrTimerPointer,
 {
-    fn start_scoped<U, F>(self, expires: Ktime, f: F) -> U
+    type TimerMode = T::TimerMode;
+
+    fn start_scoped<U, F>(
+        self,
+        expires: <<T as UnsafeHrTimerPointer>::TimerMode as HrTimerMode>::Expires,
+        f: F,
+    ) -> U
     where
         F: FnOnce() -> U,
     {
@@ -335,6 +339,11 @@ pub unsafe trait HrTimerHandle {
 /// their documentation. All the methods of this trait must operate on the same
 /// field.
 pub unsafe trait HasHrTimer<T> {
+    /// The operational mode associated with this timer.
+    ///
+    /// This defines how the expiration value is interpreted.
+    type TimerMode: HrTimerMode;
+
     /// Return a pointer to the [`HrTimer`] within `Self`.
     ///
     /// This function is useful to get access to the value without creating
@@ -382,14 +391,14 @@ pub unsafe trait HasHrTimer<T> {
     /// - `this` must point to a valid `Self`.
     /// - Caller must ensure that the pointee of `this` lives until the timer
     ///   fires or is canceled.
-    unsafe fn start(this: *const Self, expires: Ktime) {
+    unsafe fn start(this: *const Self, expires: <Self::TimerMode as HrTimerMode>::Expires) {
         // SAFETY: By function safety requirement, `this` is a valid `Self`.
         unsafe {
             bindings::hrtimer_start_range_ns(
                 Self::c_timer_ptr(this).cast_mut(),
-                expires.to_ns(),
+                expires.as_nanos(),
                 0,
-                (*Self::raw_get_timer(this)).mode.into_c(),
+                <Self::TimerMode as HrTimerMode>::C_MODE,
             );
         }
     }
@@ -411,80 +420,171 @@ impl HrTimerRestart {
     }
 }
 
-/// Operational mode of [`HrTimer`].
-// NOTE: Some of these have the same encoding on the C side, so we keep
-// `repr(Rust)` and convert elsewhere.
-#[derive(Clone, Copy, PartialEq, Eq, Debug)]
-pub enum HrTimerMode {
-    /// Timer expires at the given expiration time.
-    Absolute,
-    /// Timer expires after the given expiration time interpreted as a duration from now.
-    Relative,
-    /// Timer does not move between CPU cores.
-    Pinned,
-    /// Timer handler is executed in soft irq context.
-    Soft,
-    /// Timer handler is executed in hard irq context.
-    Hard,
-    /// Timer expires at the given expiration time.
-    /// Timer does not move between CPU cores.
-    AbsolutePinned,
-    /// Timer expires after the given expiration time interpreted as a duration from now.
-    /// Timer does not move between CPU cores.
-    RelativePinned,
-    /// Timer expires at the given expiration time.
-    /// Timer handler is executed in soft irq context.
-    AbsoluteSoft,
-    /// Timer expires after the given expiration time interpreted as a duration from now.
-    /// Timer handler is executed in soft irq context.
-    RelativeSoft,
-    /// Timer expires at the given expiration time.
-    /// Timer does not move between CPU cores.
-    /// Timer handler is executed in soft irq context.
-    AbsolutePinnedSoft,
-    /// Timer expires after the given expiration time interpreted as a duration from now.
-    /// Timer does not move between CPU cores.
-    /// Timer handler is executed in soft irq context.
-    RelativePinnedSoft,
-    /// Timer expires at the given expiration time.
-    /// Timer handler is executed in hard irq context.
-    AbsoluteHard,
-    /// Timer expires after the given expiration time interpreted as a duration from now.
-    /// Timer handler is executed in hard irq context.
-    RelativeHard,
-    /// Timer expires at the given expiration time.
-    /// Timer does not move between CPU cores.
-    /// Timer handler is executed in hard irq context.
-    AbsolutePinnedHard,
-    /// Timer expires after the given expiration time interpreted as a duration from now.
-    /// Timer does not move between CPU cores.
-    /// Timer handler is executed in hard irq context.
-    RelativePinnedHard,
+/// Time representations that can be used as expiration values in [`HrTimer`].
+pub trait HrTimerExpires {
+    /// Converts the expiration time into a nanosecond representation.
+    ///
+    /// This value corresponds to a raw ktime_t value, suitable for passing to kernel
+    /// timer functions. The interpretation (absolute vs relative) depends on the
+    /// associated [HrTimerMode] in use.
+    fn as_nanos(&self) -> i64;
 }
 
-impl HrTimerMode {
-    fn into_c(self) -> bindings::hrtimer_mode {
-        use bindings::*;
-        match self {
-            HrTimerMode::Absolute => hrtimer_mode_HRTIMER_MODE_ABS,
-            HrTimerMode::Relative => hrtimer_mode_HRTIMER_MODE_REL,
-            HrTimerMode::Pinned => hrtimer_mode_HRTIMER_MODE_PINNED,
-            HrTimerMode::Soft => hrtimer_mode_HRTIMER_MODE_SOFT,
-            HrTimerMode::Hard => hrtimer_mode_HRTIMER_MODE_HARD,
-            HrTimerMode::AbsolutePinned => hrtimer_mode_HRTIMER_MODE_ABS_PINNED,
-            HrTimerMode::RelativePinned => hrtimer_mode_HRTIMER_MODE_REL_PINNED,
-            HrTimerMode::AbsoluteSoft => hrtimer_mode_HRTIMER_MODE_ABS_SOFT,
-            HrTimerMode::RelativeSoft => hrtimer_mode_HRTIMER_MODE_REL_SOFT,
-            HrTimerMode::AbsolutePinnedSoft => hrtimer_mode_HRTIMER_MODE_ABS_PINNED_SOFT,
-            HrTimerMode::RelativePinnedSoft => hrtimer_mode_HRTIMER_MODE_REL_PINNED_SOFT,
-            HrTimerMode::AbsoluteHard => hrtimer_mode_HRTIMER_MODE_ABS_HARD,
-            HrTimerMode::RelativeHard => hrtimer_mode_HRTIMER_MODE_REL_HARD,
-            HrTimerMode::AbsolutePinnedHard => hrtimer_mode_HRTIMER_MODE_ABS_PINNED_HARD,
-            HrTimerMode::RelativePinnedHard => hrtimer_mode_HRTIMER_MODE_REL_PINNED_HARD,
-        }
+impl<C: ClockSource> HrTimerExpires for Instant<C> {
+    #[inline]
+    fn as_nanos(&self) -> i64 {
+        Instant::<C>::as_nanos(self)
+    }
+}
+
+impl HrTimerExpires for Delta {
+    #[inline]
+    fn as_nanos(&self) -> i64 {
+        Delta::as_nanos(*self)
     }
 }
 
+mod private {
+    use crate::time::ClockSource;
+
+    pub trait Sealed {}
+
+    impl<C: ClockSource> Sealed for super::AbsoluteMode<C> {}
+    impl<C: ClockSource> Sealed for super::RelativeMode<C> {}
+    impl<C: ClockSource> Sealed for super::AbsolutePinnedMode<C> {}
+    impl<C: ClockSource> Sealed for super::RelativePinnedMode<C> {}
+    impl<C: ClockSource> Sealed for super::AbsoluteSoftMode<C> {}
+    impl<C: ClockSource> Sealed for super::RelativeSoftMode<C> {}
+    impl<C: ClockSource> Sealed for super::AbsolutePinnedSoftMode<C> {}
+    impl<C: ClockSource> Sealed for super::RelativePinnedSoftMode<C> {}
+    impl<C: ClockSource> Sealed for super::AbsoluteHardMode<C> {}
+    impl<C: ClockSource> Sealed for super::RelativeHardMode<C> {}
+    impl<C: ClockSource> Sealed for super::AbsolutePinnedHardMode<C> {}
+    impl<C: ClockSource> Sealed for super::RelativePinnedHardMode<C> {}
+}
+
+/// Operational mode of [`HrTimer`].
+pub trait HrTimerMode: private::Sealed {
+    /// The C representation of hrtimer mode.
+    const C_MODE: bindings::hrtimer_mode;
+
+    /// Type representing the clock source.
+    type Clock: ClockSource;
+
+    /// Type representing the expiration specification (absolute or relative time).
+    type Expires: HrTimerExpires;
+}
+
+/// Timer that expires at a fixed point in time.
+pub struct AbsoluteMode<C: ClockSource>(PhantomData<C>);
+
+impl<C: ClockSource> HrTimerMode for AbsoluteMode<C> {
+    const C_MODE: bindings::hrtimer_mode = bindings::hrtimer_mode_HRTIMER_MODE_ABS;
+
+    type Clock = C;
+    type Expires = Instant<C>;
+}
+
+/// Timer that expires after a delay from now.
+pub struct RelativeMode<C: ClockSource>(PhantomData<C>);
+
+impl<C: ClockSource> HrTimerMode for RelativeMode<C> {
+    const C_MODE: bindings::hrtimer_mode = bindings::hrtimer_mode_HRTIMER_MODE_REL;
+
+    type Clock = C;
+    type Expires = Delta;
+}
+
+/// Timer with absolute expiration time, pinned to its current CPU.
+pub struct AbsolutePinnedMode<C: ClockSource>(PhantomData<C>);
+impl<C: ClockSource> HrTimerMode for AbsolutePinnedMode<C> {
+    const C_MODE: bindings::hrtimer_mode = bindings::hrtimer_mode_HRTIMER_MODE_ABS_PINNED;
+
+    type Clock = C;
+    type Expires = Instant<C>;
+}
+
+/// Timer with relative expiration time, pinned to its current CPU.
+pub struct RelativePinnedMode<C: ClockSource>(PhantomData<C>);
+impl<C: ClockSource> HrTimerMode for RelativePinnedMode<C> {
+    const C_MODE: bindings::hrtimer_mode = bindings::hrtimer_mode_HRTIMER_MODE_REL_PINNED;
+
+    type Clock = C;
+    type Expires = Delta;
+}
+
+/// Timer with absolute expiration, handled in soft irq context.
+pub struct AbsoluteSoftMode<C: ClockSource>(PhantomData<C>);
+impl<C: ClockSource> HrTimerMode for AbsoluteSoftMode<C> {
+    const C_MODE: bindings::hrtimer_mode = bindings::hrtimer_mode_HRTIMER_MODE_ABS_SOFT;
+
+    type Clock = C;
+    type Expires = Instant<C>;
+}
+
+/// Timer with relative expiration, handled in soft irq context.
+pub struct RelativeSoftMode<C: ClockSource>(PhantomData<C>);
+impl<C: ClockSource> HrTimerMode for RelativeSoftMode<C> {
+    const C_MODE: bindings::hrtimer_mode = bindings::hrtimer_mode_HRTIMER_MODE_REL_SOFT;
+
+    type Clock = C;
+    type Expires = Delta;
+}
+
+/// Timer with absolute expiration, pinned to CPU and handled in soft irq context.
+pub struct AbsolutePinnedSoftMode<C: ClockSource>(PhantomData<C>);
+impl<C: ClockSource> HrTimerMode for AbsolutePinnedSoftMode<C> {
+    const C_MODE: bindings::hrtimer_mode = bindings::hrtimer_mode_HRTIMER_MODE_ABS_PINNED_SOFT;
+
+    type Clock = C;
+    type Expires = Instant<C>;
+}
+
+/// Timer with absolute expiration, pinned to CPU and handled in soft irq context.
+pub struct RelativePinnedSoftMode<C: ClockSource>(PhantomData<C>);
+impl<C: ClockSource> HrTimerMode for RelativePinnedSoftMode<C> {
+    const C_MODE: bindings::hrtimer_mode = bindings::hrtimer_mode_HRTIMER_MODE_REL_PINNED_SOFT;
+
+    type Clock = C;
+    type Expires = Delta;
+}
+
+/// Timer with absolute expiration, handled in hard irq context.
+pub struct AbsoluteHardMode<C: ClockSource>(PhantomData<C>);
+impl<C: ClockSource> HrTimerMode for AbsoluteHardMode<C> {
+    const C_MODE: bindings::hrtimer_mode = bindings::hrtimer_mode_HRTIMER_MODE_ABS_HARD;
+
+    type Clock = C;
+    type Expires = Instant<C>;
+}
+
+/// Timer with relative expiration, handled in hard irq context.
+pub struct RelativeHardMode<C: ClockSource>(PhantomData<C>);
+impl<C: ClockSource> HrTimerMode for RelativeHardMode<C> {
+    const C_MODE: bindings::hrtimer_mode = bindings::hrtimer_mode_HRTIMER_MODE_REL_HARD;
+
+    type Clock = C;
+    type Expires = Delta;
+}
+
+/// Timer with absolute expiration, pinned to CPU and handled in hard irq context.
+pub struct AbsolutePinnedHardMode<C: ClockSource>(PhantomData<C>);
+impl<C: ClockSource> HrTimerMode for AbsolutePinnedHardMode<C> {
+    const C_MODE: bindings::hrtimer_mode = bindings::hrtimer_mode_HRTIMER_MODE_ABS_PINNED_HARD;
+
+    type Clock = C;
+    type Expires = Instant<C>;
+}
+
+/// Timer with relative expiration, pinned to CPU and handled in hard irq context.
+pub struct RelativePinnedHardMode<C: ClockSource>(PhantomData<C>);
+impl<C: ClockSource> HrTimerMode for RelativePinnedHardMode<C> {
+    const C_MODE: bindings::hrtimer_mode = bindings::hrtimer_mode_HRTIMER_MODE_REL_PINNED_HARD;
+
+    type Clock = C;
+    type Expires = Delta;
+}
+
 /// Use to implement the [`HasHrTimer<T>`] trait.
 ///
 /// See [`module`] documentation for an example.
@@ -496,12 +596,16 @@ macro_rules! impl_has_hr_timer {
         impl$({$($generics:tt)*})?
             HasHrTimer<$timer_type:ty>
             for $self:ty
-        { self.$field:ident }
+        {
+            mode : $mode:ty,
+            field : self.$field:ident $(,)?
+        }
         $($rest:tt)*
     ) => {
         // SAFETY: This implementation of `raw_get_timer` only compiles if the
         // field has the right type.
         unsafe impl$(<$($generics)*>)? $crate::time::hrtimer::HasHrTimer<$timer_type> for $self {
+            type TimerMode = $mode;
 
             #[inline]
             unsafe fn raw_get_timer(
diff --git a/rust/kernel/time/hrtimer/arc.rs b/rust/kernel/time/hrtimer/arc.rs
index ccf1e66e5b2d..ed490a7a8950 100644
--- a/rust/kernel/time/hrtimer/arc.rs
+++ b/rust/kernel/time/hrtimer/arc.rs
@@ -4,8 +4,8 @@ use super::HasHrTimer;
 use super::HrTimer;
 use super::HrTimerCallback;
 use super::HrTimerHandle;
+use super::HrTimerMode;
 use super::HrTimerPointer;
-use super::Ktime;
 use super::RawHrTimerCallback;
 use crate::sync::Arc;
 use crate::sync::ArcBorrow;
@@ -54,9 +54,13 @@ where
     T: HasHrTimer<T>,
     T: for<'a> HrTimerCallback<Pointer<'a> = Self>,
 {
+    type TimerMode = <T as HasHrTimer<T>>::TimerMode;
     type TimerHandle = ArcHrTimerHandle<T>;
 
-    fn start(self, expires: Ktime) -> ArcHrTimerHandle<T> {
+    fn start(
+        self,
+        expires: <<T as HasHrTimer<T>>::TimerMode as HrTimerMode>::Expires,
+    ) -> ArcHrTimerHandle<T> {
         // SAFETY:
         //  - We keep `self` alive by wrapping it in a handle below.
         //  - Since we generate the pointer passed to `start` from a valid
diff --git a/rust/kernel/time/hrtimer/pin.rs b/rust/kernel/time/hrtimer/pin.rs
index 293ca9cf058c..aef16d9ee2f0 100644
--- a/rust/kernel/time/hrtimer/pin.rs
+++ b/rust/kernel/time/hrtimer/pin.rs
@@ -4,7 +4,7 @@ use super::HasHrTimer;
 use super::HrTimer;
 use super::HrTimerCallback;
 use super::HrTimerHandle;
-use super::Ktime;
+use super::HrTimerMode;
 use super::RawHrTimerCallback;
 use super::UnsafeHrTimerPointer;
 use core::pin::Pin;
@@ -54,9 +54,13 @@ where
     T: HasHrTimer<T>,
     T: HrTimerCallback<Pointer<'a> = Self>,
 {
+    type TimerMode = <T as HasHrTimer<T>>::TimerMode;
     type TimerHandle = PinHrTimerHandle<'a, T>;
 
-    unsafe fn start(self, expires: Ktime) -> Self::TimerHandle {
+    unsafe fn start(
+        self,
+        expires: <<T as HasHrTimer<T>>::TimerMode as HrTimerMode>::Expires,
+    ) -> Self::TimerHandle {
         // Cast to pointer
         let self_ptr: *const T = self.get_ref();
 
@@ -79,7 +83,7 @@ where
 
     unsafe extern "C" fn run(ptr: *mut bindings::hrtimer) -> bindings::hrtimer_restart {
         // `HrTimer` is `repr(C)`
-        let timer_ptr = ptr as *mut HrTimer<T>;
+        let timer_ptr = ptr.cast::<HrTimer<T>>();
 
         // SAFETY: By the safety requirement of this function, `timer_ptr`
         // points to a `HrTimer<T>` contained in an `T`.
diff --git a/rust/kernel/time/hrtimer/pin_mut.rs b/rust/kernel/time/hrtimer/pin_mut.rs
index 6033572d35ad..767d0a4e8a2c 100644
--- a/rust/kernel/time/hrtimer/pin_mut.rs
+++ b/rust/kernel/time/hrtimer/pin_mut.rs
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 
 use super::{
-    HasHrTimer, HrTimer, HrTimerCallback, HrTimerHandle, Ktime, RawHrTimerCallback,
+    HasHrTimer, HrTimer, HrTimerCallback, HrTimerHandle, HrTimerMode, RawHrTimerCallback,
     UnsafeHrTimerPointer,
 };
 use core::{marker::PhantomData, pin::Pin, ptr::NonNull};
@@ -52,9 +52,13 @@ where
     T: HasHrTimer<T>,
     T: HrTimerCallback<Pointer<'a> = Self>,
 {
+    type TimerMode = <T as HasHrTimer<T>>::TimerMode;
     type TimerHandle = PinMutHrTimerHandle<'a, T>;
 
-    unsafe fn start(mut self, expires: Ktime) -> Self::TimerHandle {
+    unsafe fn start(
+        mut self,
+        expires: <<T as HasHrTimer<T>>::TimerMode as HrTimerMode>::Expires,
+    ) -> Self::TimerHandle {
         // SAFETY:
         // - We promise not to move out of `self`. We only pass `self`
         //   back to the caller as a `Pin<&mut self>`.
@@ -83,7 +87,7 @@ where
 
     unsafe extern "C" fn run(ptr: *mut bindings::hrtimer) -> bindings::hrtimer_restart {
         // `HrTimer` is `repr(C)`
-        let timer_ptr = ptr as *mut HrTimer<T>;
+        let timer_ptr = ptr.cast::<HrTimer<T>>();
 
         // SAFETY: By the safety requirement of this function, `timer_ptr`
         // points to a `HrTimer<T>` contained in an `T`.
diff --git a/rust/kernel/time/hrtimer/tbox.rs b/rust/kernel/time/hrtimer/tbox.rs
index 29526a5da203..ec08303315f2 100644
--- a/rust/kernel/time/hrtimer/tbox.rs
+++ b/rust/kernel/time/hrtimer/tbox.rs
@@ -4,8 +4,8 @@ use super::HasHrTimer;
 use super::HrTimer;
 use super::HrTimerCallback;
 use super::HrTimerHandle;
+use super::HrTimerMode;
 use super::HrTimerPointer;
-use super::Ktime;
 use super::RawHrTimerCallback;
 use crate::prelude::*;
 use core::ptr::NonNull;
@@ -64,9 +64,13 @@ where
     T: for<'a> HrTimerCallback<Pointer<'a> = Pin<Box<T, A>>>,
     A: crate::alloc::Allocator,
 {
+    type TimerMode = <T as HasHrTimer<T>>::TimerMode;
     type TimerHandle = BoxHrTimerHandle<T, A>;
 
-    fn start(self, expires: Ktime) -> Self::TimerHandle {
+    fn start(
+        self,
+        expires: <<T as HasHrTimer<T>>::TimerMode as HrTimerMode>::Expires,
+    ) -> Self::TimerHandle {
         // SAFETY:
         //  - We will not move out of this box during timer callback (we pass an
         //    immutable reference to the callback).