bluetooth: host_extension: RTCx time diff may be negative

Radio notification callback host extension checks the offset between
system clock and second RTC instance. The implementation assumes given
order of RTCx startup. To remove the constraint use singed integer to
store time difference. Also an assert that enforces the time difference
to be larger or equal to zero.

Signed-off-by: Piotr Pryga <[email protected]>

Author: ppryga-nordic

subsys/bluetooth/host_extensions/radio_notification_conn_cb.c

@@ -12,7 +12,10 @@
 
 #if defined(CONFIG_SOC_COMPATIBLE_NRF52X) || defined(CONFIG_SOC_COMPATIBLE_NRF5340_CPUNET)
 #include <hal/nrf_rtc.h>
-static uint32_t sys_clock_start_to_bt_clk_start_us;
+/* Use signed integer to allow to get time difference no matter of order in which RTCx instances
+ * are started.
+ */
+static int32_t sys_clock_start_to_bt_clk_start_us;
 #endif
 
 static uint32_t configured_prepare_distance_us;
@@ -91,7 +94,7 @@ static bool on_vs_evt(struct net_buf_simple *buf)
 
 #if defined(CONFIG_SOC_COMPATIBLE_NRF52X) || defined(CONFIG_SOC_COMPATIBLE_NRF5340_CPUNET)
 	timer_trigger_us -= sys_clock_start_to_bt_clk_start_us;
-#endif
+#endif /* CONFIG_SOC_COMPATIBLE_NRF52X || CONFIG_SOC_COMPATIBLE_NRF5340_CPUNET */
 
 	/* Start/Restart a timer triggering every conn_interval_us from the last anchor point. */
 	k_timer_start(&timers[conn_index], K_TIMEOUT_ABS_US(timer_trigger_us),
@@ -168,12 +171,10 @@ static int set_sys_clock_start_to_bt_clk_start_us(void)
 		}
 	}
 
-	const uint64_t rtc_ticks_in_femto_units = 30517578125UL;
-
-	__ASSERT_NO_MSG(ticks_difference >= 0);
+	const int64_t rtc_ticks_in_femto_units = 30517578125L;
 
 	sys_clock_start_to_bt_clk_start_us =
-		((ticks_difference * rtc_ticks_in_femto_units) / 1000000000UL);
+		((ticks_difference * rtc_ticks_in_femto_units) / 1000000000L);
 	return 0;
 }