rust: hrtimer: add HrTimerMode

Allow selection of timer mode by passing a `HrTimerMode` variant to
`HrTimer::new`.

Acked-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20250309-hrtimer-v3-v6-12-rc2-v12-11-73586e2bd5f1@kernel.org
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>

Author: Andreas Hindborg

rust/kernel/time/hrtimer.rs

@@ -80,6 +80,7 @@ use core::marker::PhantomData;
 pub struct HrTimer<T> {
     #[pin]
     timer: Opaque<bindings::hrtimer>,
+    mode: HrTimerMode,
     _t: PhantomData<T>,
 }
 
@@ -93,7 +94,7 @@ unsafe impl<T> Sync for HrTimer<T> {}
 
 impl<T> HrTimer<T> {
     /// Return an initializer for a new timer instance.
-    pub fn new() -> impl PinInit<Self>
+    pub fn new(mode: HrTimerMode) -> impl PinInit<Self>
     where
         T: HrTimerCallback,
     {
@@ -108,10 +109,11 @@ impl<T> HrTimer<T> {
                         place,
                         Some(T::Pointer::run),
                         bindings::CLOCK_MONOTONIC as i32,
-                        bindings::hrtimer_mode_HRTIMER_MODE_REL,
+                        mode.into_c(),
                     );
                 }
             }),
+            mode: mode,
             _t: PhantomData,
         })
     }
@@ -369,7 +371,7 @@ pub unsafe trait HasHrTimer<T> {
                 Self::c_timer_ptr(this).cast_mut(),
                 expires.to_ns(),
                 0,
-                bindings::hrtimer_mode_HRTIMER_MODE_REL,
+                (*Self::raw_get_timer(this)).mode.into_c(),
             );
         }
     }
@@ -393,6 +395,80 @@ 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,
+}
+
+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,
+        }
+    }
+}
+
 /// Use to implement the [`HasHrTimer<T>`] trait.
 ///
 /// See [`module`] documentation for an example.