[PATCH v3 05/13] rust: hrtimer: allow timer restart from timer handler

[Andreas Hindborg <a.hindborg@kernel.org>]

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/hrtimer.rs     | 28 +++++++++++++++++++++++++++-
 rust/kernel/hrtimer/arc.rs |  4 +---
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/rust/kernel/hrtimer.rs b/rust/kernel/hrtimer.rs
index 6427b0450c694105190c8cddea0c768ab195aca2..eeed2afd501b64b94d57cc658616659e28785078 100644
--- a/rust/kernel/hrtimer.rs
+++ b/rust/kernel/hrtimer.rs
@@ -176,7 +176,7 @@ pub trait TimerCallback {
     type CallbackTargetParameter<'a>;
 
     /// Called by the timer logic when the timer fires.
-    fn run(this: Self::CallbackTargetParameter<'_>)
+    fn run(this: Self::CallbackTargetParameter<'_>) -> TimerRestart
     where
         Self: Sized;
 }
@@ -270,6 +270,32 @@ unsafe fn start(self_ptr: *const Self, expires: Ktime) {
     }
 }
 
+/// Restart policy for timers.
+pub enum TimerRestart {
+    /// Timer should not be restarted.
+    NoRestart,
+    /// Timer should be restarted.
+    Restart,
+}
+
+impl From<u32> for TimerRestart {
+    fn from(value: bindings::hrtimer_restart) -> Self {
+        match value {
+            0 => Self::NoRestart,
+            _ => Self::Restart,
+        }
+    }
+}
+
+impl From<TimerRestart> for bindings::hrtimer_restart {
+    fn from(value: TimerRestart) -> Self {
+        match value {
+            TimerRestart::NoRestart => bindings::hrtimer_restart_HRTIMER_NORESTART,
+            TimerRestart::Restart => bindings::hrtimer_restart_HRTIMER_RESTART,
+        }
+    }
+}
+
 /// Use to implement the [`HasTimer<T>`] trait.
 ///
 /// See [`module`] documentation for an example.
diff --git a/rust/kernel/hrtimer/arc.rs b/rust/kernel/hrtimer/arc.rs
index 881de053ecad866a26e46a0123ec2bf38511c2bc..c6283bd0dbb10dbc733c3f4092f107db2f3c5c5f 100644
--- a/rust/kernel/hrtimer/arc.rs
+++ b/rust/kernel/hrtimer/arc.rs
@@ -82,8 +82,6 @@ impl<U> RawTimerCallback for Arc<U>
         // timer. This `U` is contained in an `Arc`.
         let receiver = unsafe { ArcBorrow::from_raw(data_ptr) };
 
-        U::run(receiver);
-
-        bindings::hrtimer_restart_HRTIMER_NORESTART
+        U::run(receiver).into()
     }
 }

-- 
2.46.0