[PATCH v6 5/7] rust: hrtimer: Add forward_now() to HrTimer and HrTimerCallbackContext

[Lyude Paul <lyude@redhat.com>]

Using the HrTimer::raw_time_cb() function, we can now add an equivalent to
hrtimer_forward_now() to both HrTimer and HrTimerCallbackContext.

Signed-off-by: Lyude Paul <lyude@redhat.com>

---
V2:
* Change from Ktime to Delta
* Make sure that forward_now() takes a mutable reference to the timer
  struct
* Reword this to point out that we're adding forward_now() to both callback
  context and mutable timer reference
* Rename interval to duration

V4:
* Fix rust documentation for HrTimerCallbackContext (forgot to update both
  forward_now() declarations)
* Use Pin<&mut Self> for context-less forward.

V6:
* Drop raw_cb_time(), use Instant::now() instead
* Split out expires() from this patch, at some point it seems I mistakenly
  combined it with this patch

Signed-off-by: Lyude Paul <lyude@redhat.com>
---
 rust/kernel/time/hrtimer.rs | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/rust/kernel/time/hrtimer.rs b/rust/kernel/time/hrtimer.rs
index a8fb176e599e8..fa5a3ae81723b 100644
--- a/rust/kernel/time/hrtimer.rs
+++ b/rust/kernel/time/hrtimer.rs
@@ -212,6 +212,17 @@ pub fn forward(self: Pin<&mut Self>, now: HrTimerInstant<T>, interval: Delta) ->
         //   exclusive access to it - fulfilling the requirements of the C API.
         unsafe { Self::raw_forward(self.get_unchecked_mut(), now, interval) }
     }
+
+    /// Conditionally forward the timer.
+    ///
+    /// This is a variant of [`forward()`](Self::forward) that uses an interval after the current
+    /// time of the base clock for the [`HrTimer`].
+    pub fn forward_now(self: Pin<&mut Self>, interval: Delta) -> u64
+    where
+        T: HasHrTimer<T>,
+    {
+        self.forward(HrTimerInstant::<T>::now(), interval)
+    }
 }
 
 /// Implemented by pointer types that point to structs that contain a [`HrTimer`].
@@ -687,6 +698,14 @@ pub fn forward(&mut self, now: HrTimerInstant<T>, interval: Delta) -> u64 {
         // - By our type invariants, `self.0` always points to a valid `HrTimer<T>`
         unsafe { HrTimer::<T>::raw_forward(self.0.as_ptr(), now, interval) }
     }
+
+    /// Conditionally forward the timer.
+    ///
+    /// This is a variant of [`HrTimerCallbackContext::forward()`] that uses an interval after the
+    /// current time of the base clock for the [`HrTimer`].
+    pub fn forward_now(&mut self, duration: Delta) -> u64 {
+        self.forward(HrTimerInstant::<T>::now(), duration)
+    }
 }
 
 /// Use to implement the [`HasHrTimer<T>`] trait.
-- 
2.50.0