This patch allows timer handlers to report that they want a timer to be
restarted after the timer handler has finished executing.

Also update the `hrtimer` documentation to showcase the new feature.

Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
---
 rust/kernel/time/hrtimer.rs     | 28 +++++++++++++++++++++++++++-
 rust/kernel/time/hrtimer/arc.rs |  4 +---
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/rust/kernel/time/hrtimer.rs b/rust/kernel/time/hrtimer.rs
index 3494c00481a4bd25735edf44b6bdcbec9810243e..3ed7f5ee92fc5f9f4cc108c373ac40480f5307d1 100644
--- a/rust/kernel/time/hrtimer.rs
+++ b/rust/kernel/time/hrtimer.rs
@@ -183,7 +183,7 @@ pub trait HrTimerCallback {
     type CallbackTargetParameter<'a>;
 
     /// Called by the timer logic when the timer fires.
-    fn run(this: Self::CallbackTargetParameter<'_>)
+    fn run(this: Self::CallbackTargetParameter<'_>) -> HrTimerRestart
     where
         Self: Sized;
 }
@@ -278,6 +278,32 @@ unsafe fn start(self_ptr: *const Self, expires: Ktime) {
     }
 }
 
+/// Restart policy for timers.
+pub enum HrTimerRestart {
+    /// Timer should not be restarted.
+    NoRestart,
+    /// Timer should be restarted.
+    Restart,
+}
+
+impl From<bindings::hrtimer_restart> for HrTimerRestart {
+    fn from(value: u32) -> Self {
+        match value {
+            bindings::hrtimer_restart_HRTIMER_NORESTART => Self::NoRestart,
+            _ => Self::Restart,
+        }
+    }
+}
+
+impl From<HrTimerRestart> for bindings::hrtimer_restart {
+    fn from(value: HrTimerRestart) -> Self {
+        match value {
+            HrTimerRestart::NoRestart => bindings::hrtimer_restart_HRTIMER_NORESTART,
+            HrTimerRestart::Restart => bindings::hrtimer_restart_HRTIMER_RESTART,
+        }
+    }
+}
+
 /// Use to implement the [`HasHrTimer<T>`] trait.
 ///
 /// See [`module`] documentation for an example.
diff --git a/rust/kernel/time/hrtimer/arc.rs b/rust/kernel/time/hrtimer/arc.rs
index d1c90631d00362bdc38be1ccc75429ae294ab544..109eded0e73be853313abbe1a3540a5b1b8706d7 100644
--- a/rust/kernel/time/hrtimer/arc.rs
+++ b/rust/kernel/time/hrtimer/arc.rs
@@ -82,8 +82,6 @@ impl<T> RawHrTimerCallback for Arc<T>
         // timer. This `T` is contained in an `Arc`.
         let receiver = unsafe { ArcBorrow::from_raw(data_ptr) };
 
-        T::run(receiver);
-
-        bindings::hrtimer_restart_HRTIMER_NORESTART
+        T::run(receiver).into()
     }
 }

-- 
2.47.0