arch/risc-v/src/common/riscv_mtimer.c: Add risc-v tick timer operations

Add the mtimer _tick operations for use when tickless mode is not used.
This corrects the tick-based timing calculations, removing tick timer drift
and rounding errors causing early wdog expirations.

Signed-off-by: Jukka Laitinen <[email protected]>

arch/risc-v/src/common/riscv_mtimer.c

@@ -68,16 +68,30 @@ static int riscv_mtimer_cancel(struct oneshot_lowerhalf_s *lower,
 static int riscv_mtimer_current(struct oneshot_lowerhalf_s *lower,
                                 struct timespec *ts);
 
+static int riscv_mtimer_tick_max_delay(struct oneshot_lowerhalf_s *lower,
+                                       clock_t *ticks);
+static int riscv_mtimer_tick_start(struct oneshot_lowerhalf_s *lower,
+                                   oneshot_callback_t callback, void *arg,
+                                   clock_t ticks);
+static int riscv_mtimer_tick_cancel(struct oneshot_lowerhalf_s *lower,
+                                    clock_t *ticks);
+static int riscv_mtimer_tick_current(struct oneshot_lowerhalf_s *lower,
+                                     clock_t *ticks);
+
 /****************************************************************************
  * Private Data
  ****************************************************************************/
 
 static const struct oneshot_operations_s g_riscv_mtimer_ops =
 {
-  .max_delay = riscv_mtimer_max_delay,
-  .start     = riscv_mtimer_start,
-  .cancel    = riscv_mtimer_cancel,
-  .current   = riscv_mtimer_current,
+  .max_delay      = riscv_mtimer_max_delay,
+  .start          = riscv_mtimer_start,
+  .cancel         = riscv_mtimer_cancel,
+  .current        = riscv_mtimer_current,
+  .tick_start     = riscv_mtimer_tick_start,
+  .tick_current   = riscv_mtimer_tick_current,
+  .tick_max_delay = riscv_mtimer_tick_max_delay,
+  .tick_cancel    = riscv_mtimer_tick_cancel,
 };
 
 /****************************************************************************
@@ -189,6 +203,32 @@ static int riscv_mtimer_max_delay(struct oneshot_lowerhalf_s *lower,
   return 0;
 }
 
+/****************************************************************************
+ * Name: riscv_mtimer_tick_max_delay
+ *
+ * Description:
+ *   Determine the maximum delay of the one-shot timer
+ *
+ * Input Parameters:
+ *   lower   An instance of the lower-half oneshot state structure.  This
+ *           structure must have been previously initialized via a call to
+ *           oneshot_initialize();
+ *   ticks   The location in which to return the maximum delay.
+ *
+ * Returned Value:
+ *   Zero (OK) is returned on success; a negated errno value is returned
+ *   on failure.
+ *
+ ****************************************************************************/
+
+static int riscv_mtimer_tick_max_delay(struct oneshot_lowerhalf_s *lower,
+                                       clock_t *ticks)
+{
+  *ticks = (clock_t)UINT64_MAX;
+
+  return 0;
+}
+
 /****************************************************************************
  * Name: riscv_mtimer_start
  *
@@ -235,6 +275,53 @@ static int riscv_mtimer_start(struct oneshot_lowerhalf_s *lower,
   return 0;
 }
 
+/****************************************************************************
+ * Name: riscv_mtimer_tick_start
+ *
+ * Description:
+ *   Start the oneshot timer
+ *
+ * Input Parameters:
+ *   lower   An instance of the lower-half oneshot state structure.  This
+ *           structure must have been previously initialized via a call to
+ *           oneshot_initialize();
+ *   handler The function to call when when the oneshot timer expires.
+ *   arg     An opaque argument that will accompany the callback.
+ *   ticks   Provides the duration of the one shot timer.
+ *
+ * Returned Value:
+ *   Zero (OK) is returned on success; a negated errno value is returned
+ *   on failure.
+ *
+ ****************************************************************************/
+
+static int riscv_mtimer_tick_start(struct oneshot_lowerhalf_s *lower,
+                              oneshot_callback_t callback, void *arg,
+                              clock_t ticks)
+{
+  struct riscv_mtimer_lowerhalf_s *priv =
+    (struct riscv_mtimer_lowerhalf_s *)lower;
+  irqstate_t flags;
+  uint64_t mtime;
+  clock_t current;
+  uint64_t alarm;
+
+  flags = up_irq_save();
+
+  mtime = riscv_mtimer_get_mtime(priv);
+  current = mtime * TICK_PER_SEC / priv->freq;
+  alarm = (current + ticks) * priv->freq / TICK_PER_SEC;
+
+  priv->alarm    = alarm;
+  priv->callback = callback;
+  priv->arg      = arg;
+
+  riscv_mtimer_set_mtimecmp(priv, priv->alarm);
+
+  up_irq_restore(flags);
+  return 0;
+}
+
 /****************************************************************************
  * Name: riscv_mtimer_cancel
  *
@@ -290,6 +377,59 @@ static int riscv_mtimer_cancel(struct oneshot_lowerhalf_s *lower,
   return 0;
 }
 
+/****************************************************************************
+ * Name: riscv_mtimer_tick_cancel
+ *
+ * Description:
+ *   Cancel the oneshot timer and return the time remaining on the timer.
+ *
+ *   NOTE: This function may execute at a high rate with no timer running (as
+ *   when pre-emption is enabled and disabled).
+ *
+ * Input Parameters:
+ *   lower   Caller allocated instance of the oneshot state structure.  This
+ *           structure must have been previously initialized via a call to
+ *           oneshot_initialize();
+ *   ticks   The location in which to return the time remaining on the
+ *           oneshot timer.  A time of zero is returned if the timer is
+ *           not running.
+ *
+ * Returned Value:
+ *   Zero (OK) is returned on success.  A call to up_timer_cancel() when
+ *   the timer is not active should also return success; a negated errno
+ *   value is returned on any failure.
+ *
+ ****************************************************************************/
+
+static int riscv_mtimer_tick_cancel(struct oneshot_lowerhalf_s *lower,
+                                    clock_t *ticks)
+{
+  struct riscv_mtimer_lowerhalf_s *priv =
+    (struct riscv_mtimer_lowerhalf_s *)lower;
+  uint64_t mtime;
+  uint64_t alarm;
+  irqstate_t flags;
+
+  flags = up_irq_save();
+
+  alarm = priv->alarm;
+
+  mtime = riscv_mtimer_get_mtime(priv);
+
+  riscv_mtimer_set_mtimecmp(priv, mtime + UINT64_MAX);
+
+  *ticks = alarm * TICK_PER_SEC / priv->freq -
+    mtime * TICK_PER_SEC / priv->freq;
+
+  priv->alarm    = 0;
+  priv->callback = NULL;
+  priv->arg      = NULL;
+
+  up_irq_restore(flags);
+
+  return 0;
+}
+
 /****************************************************************************
  * Name: riscv_mtimer_current
  *
@@ -336,6 +476,37 @@ static int riscv_mtimer_interrupt(int irq, void *context, void *arg)
   return 0;
 }
 
+/****************************************************************************
+ * Name: riscv_mtimer_tick_current
+ *
+ * Description:
+ *  Get the current time.
+ *
+ * Input Parameters:
+ *   lower   Caller allocated instance of the oneshot state structure.  This
+ *           structure must have been previously initialized via a call to
+ *           oneshot_initialize();
+ *   ticks   The location in which to return the current time. A time of zero
+ *           is returned for the initialization moment.
+ *
+ * Returned Value:
+ *   Zero (OK) is returned on success, a negated errno value is returned on
+ *   any failure.
+ *
+ ****************************************************************************/
+
+static int riscv_mtimer_tick_current(struct oneshot_lowerhalf_s *lower,
+                                     clock_t *ticks)
+{
+  struct riscv_mtimer_lowerhalf_s *priv =
+    (struct riscv_mtimer_lowerhalf_s *)lower;
+  uint64_t mtime = riscv_mtimer_get_mtime(priv);
+
+  *ticks = mtime * TICK_PER_SEC / priv->freq;
+
+  return OK;
+}
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/