time: some const fns

embassy/src/time/duration.rs

@@ -8,7 +8,7 @@ pub struct Duration {
 }
 
 impl Duration {
-    pub fn into_ticks(&self) -> u32 {
+    pub const fn into_ticks(&self) -> u32 {
         self.ticks
     }
 

embassy/src/time/instant.rs

@@ -17,7 +17,11 @@ impl Instant {
         Instant { ticks: now() }
     }
 
-    pub fn into_ticks(&self) -> u64 {
+    pub const fn from_ticks(ticks: u64) -> Self {
+        Self { ticks }
+    }
+
+    pub const fn into_ticks(&self) -> u64 {
         self.ticks
     }