From fc68d9c3a3973f818ca5df66cf0f61d823c312b6 Mon Sep 17 00:00:00 2001
From: Kaspar Schleiser <kaspar@schleiser.de>
Date: Mon, 4 May 2020 15:47:37 +0200
Subject: [PATCH] sys/ztimer: properly initialize intermediate extension
 callback

---
 sys/include/ztimer.h          | 17 +++++++++++++++++
 sys/ztimer/convert_frac.c     |  1 +
 sys/ztimer/convert_muldiv64.c |  1 +
 sys/ztimer/periph_rtt.c       |  1 +
 sys/ztimer/periph_timer.c     |  1 +
 5 files changed, 21 insertions(+)

diff --git a/sys/include/ztimer.h b/sys/include/ztimer.h
index 37dd23a3a6..66dcab6b47 100644
--- a/sys/include/ztimer.h
+++ b/sys/include/ztimer.h
@@ -485,6 +485,23 @@ void ztimer_update_head_offset(ztimer_clock_t *clock);
  */
 void ztimer_init(void);
 
+/**
+ * @brief   Initialize possible ztimer extension intermediate timer
+ *
+ * This will basically just set a timer to (clock->max_value >> 1), *if*
+ * max_value is not UINT32_MAX.
+ *
+ * This is called automatically by all ztimer backends and extension modules.
+ *
+ * @internal
+ */
+static inline void ztimer_init_extend(ztimer_clock_t *clock)
+{
+    if (clock->max_value < UINT32_MAX) {
+        clock->ops->set(clock, clock->max_value >> 1);
+    }
+}
+
 /* default ztimer virtual devices */
 /**
  * @brief   Default ztimer microsecond clock
diff --git a/sys/ztimer/convert_frac.c b/sys/ztimer/convert_frac.c
index f468997dd6..71eb74164b 100644
--- a/sys/ztimer/convert_frac.c
+++ b/sys/ztimer/convert_frac.c
@@ -91,6 +91,7 @@ void ztimer_convert_frac_init(ztimer_convert_frac_t *self, ztimer_clock_t *lower
     ztimer_convert_frac_compute_scale(self, freq_self, freq_lower);
     if (freq_self < freq_lower) {
         self->super.super.max_value = frac_scale(&self->scale_set, UINT32_MAX);
+        ztimer_init_extend(&self->super.super);
     }
     else {
         DEBUG("ztimer_convert_frac_init: rounding up val:%" PRIu32"\n",
diff --git a/sys/ztimer/convert_muldiv64.c b/sys/ztimer/convert_muldiv64.c
index 8732448076..d124d581e8 100644
--- a/sys/ztimer/convert_muldiv64.c
+++ b/sys/ztimer/convert_muldiv64.c
@@ -120,4 +120,5 @@ void ztimer_convert_muldiv64_init(
     ztimer_convert_muldiv64->super.super.ops = &_ztimer_convert_muldiv64_ops;
     ztimer_convert_muldiv64->div = div;
     ztimer_convert_muldiv64->mul = mul;
+    ztimer_init_extend(&ztimer_convert_muldiv64->super.super);
 }
diff --git a/sys/ztimer/periph_rtt.c b/sys/ztimer/periph_rtt.c
index 64b5c63398..42edfebc2c 100644
--- a/sys/ztimer/periph_rtt.c
+++ b/sys/ztimer/periph_rtt.c
@@ -88,4 +88,5 @@ void ztimer_periph_rtt_init(ztimer_periph_rtt_t *clock)
     clock->max_value = RTT_MAX_VALUE;
     rtt_init();
     rtt_poweron();
+    ztimer_init_extend(clock);
 }
diff --git a/sys/ztimer/periph_timer.c b/sys/ztimer/periph_timer.c
index be789a12eb..ce13d06902 100644
--- a/sys/ztimer/periph_timer.c
+++ b/sys/ztimer/periph_timer.c
@@ -79,4 +79,5 @@ void ztimer_periph_timer_init(ztimer_periph_timer_t *clock, tim_t dev, unsigned
     clock->super.ops = &_ztimer_periph_timer_ops;
     clock->super.max_value = max_val;
     timer_init(dev, freq, _ztimer_periph_timer_callback, clock);
+    ztimer_init_extend(&clock->super);
 }