supervisor: tick: add supervisor_fake_tick

supervisor/shared/tick.c

@@ -88,4 +88,7 @@ void supervisor_run_background_tasks_if_tick() {
     run_background_tasks();
 }
 
+void supervisor_fake_tick() {
+    uint32_t now32 = ticks_ms;
+    background_ticks_ms32 = (now32 - 1);
 }

supervisor/shared/tick.h

@@ -36,6 +36,13 @@
  * interrupt context.
  */
 extern void supervisor_tick(void);
+/** @brief Cause background tasks to be called soon
+ *
+ * Normally, background tasks are only run once per tick.  For other cases where
+ * an event noticed from an interrupt context needs to be completed by a background
+ * task activity, the interrupt can call supervisor_fake_tick.
+ */
+extern void supervisor_fake_tick(void);
 /** @brief Get the lower 32 bits of the time in milliseconds
  *
  * This can be more efficient than supervisor_ticks_ms64, for sites where a wraparound