drivers: timer: extend nrf_rtc_timer

This commit introduces the following changes: * nrf_rtc_timer is extended with a capability to handle RTC overflow, allowing it to operate on absolute RTC ticks, rather than relative ticks. * overflow handling is ZLI-proof and relies on the sys clock handler being executed twice every RTC counter's overflow. * callbacks are given an absolute RTC tick value as a parameter instead of CC register's value. The absolute RTC tick value is the RTC counter value set during CC channel configuration extended to 64 bits. * in case the timer's target time is in the past or is the current tick, the timer fires as soon as possible, however still from the RTC's ISR context. * in case an active timer is set again with the same target time, it is not scheduled again - only its event data is updated. Otherwise, the timer is scheduled as usual. * a scheduled timer can be aborted. * system clock functions are now using 64 bit values internally. Signed-off-by: Andrzej Kuroś <andrzej.kuros@nordicsemi.no> Signed-off-by: Jedrzej Ciupis <jedrzej.ciupis@nordicsemi.no> Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no> Signed-off-by: Paweł Kwiek <pawel.kwiek@nordicsemi.no>
2021-09-30 15:07:40 +02:00 · 2021-09-30 15:07:40 +02:00 · 26e297572a
commit 26e297572a
parent 02cee09308
3 changed files with 474 additions and 131 deletions
--- a/drivers/timer/nrf_rtc_timer.c
+++ b/drivers/timer/nrf_rtc_timer.c
@ -13,8 +13,6 @@
 #include <drivers/timer/nrf_rtc_timer.h>
 #include <sys_clock.h>
 #include <hal/nrf_rtc.h>
-#include <spinlock.h>
-

 #define EXT_CHAN_COUNT CONFIG_NRF_RTC_TIMER_USER_CHAN_COUNT
 #define CHAN_COUNT (EXT_CHAN_COUNT + 1)
@ -26,7 +24,8 @@

 BUILD_ASSERT(CHAN_COUNT <= RTC_CH_COUNT, "Not enough compare channels");

-#define COUNTER_SPAN BIT(24)
+#define COUNTER_BIT_WIDTH 24U
+#define COUNTER_SPAN BIT(COUNTER_BIT_WIDTH)
 #define COUNTER_MAX (COUNTER_SPAN - 1U)
 #define COUNTER_HALF_SPAN (COUNTER_SPAN / 2U)
 #define CYC_PER_TICK (sys_clock_hw_cycles_per_sec()	\
@ -34,18 +33,25 @@ BUILD_ASSERT(CHAN_COUNT <= RTC_CH_COUNT, "Not enough compare channels");
 #define MAX_TICKS ((COUNTER_HALF_SPAN - CYC_PER_TICK) / CYC_PER_TICK)
 #define MAX_CYCLES (MAX_TICKS * CYC_PER_TICK)

-static struct k_spinlock lock;
+#define OVERFLOW_RISK_RANGE_END (COUNTER_SPAN / 16)
+#define ANCHOR_RANGE_START (COUNTER_SPAN / 8)
+#define ANCHOR_RANGE_END (7 * COUNTER_SPAN / 8)
+#define TARGET_TIME_INVALID (UINT64_MAX)

-static uint32_t last_count;
+static volatile uint32_t overflow_cnt;
+static volatile uint64_t anchor;
+static uint64_t last_count;

 struct z_nrf_rtc_timer_chan_data {
 	z_nrf_rtc_timer_compare_handler_t callback;
 	void *user_context;
+	volatile uint64_t target_time;
 };

 static struct z_nrf_rtc_timer_chan_data cc_data[CHAN_COUNT];
 static atomic_t int_mask;
 static atomic_t alloc_mask;
+static atomic_t force_isr_mask;

 static uint32_t counter_sub(uint32_t a, uint32_t b)
 {
@ -82,9 +88,33 @@ static uint32_t counter(void)
 	return nrf_rtc_counter_get(RTC);
 }

-uint32_t z_nrf_rtc_timer_read(void)
+static uint32_t absolute_time_to_cc(uint64_t absolute_time)
 {
-	return nrf_rtc_counter_get(RTC);
+	/* 24 least significant bits represent target CC value */
+	return absolute_time & COUNTER_MAX;
+}
+
+static uint32_t full_int_lock(void)
+{
+	uint32_t mcu_critical_state;
+
+	if (IS_ENABLED(CONFIG_ZERO_LATENCY_IRQS)) {
+		mcu_critical_state = __get_PRIMASK();
+		__disable_irq();
+	} else {
+		mcu_critical_state = irq_lock();
+	}
+
+	return mcu_critical_state;
+}
+
+static void full_int_unlock(uint32_t mcu_critical_state)
+{
+	if (IS_ENABLED(CONFIG_ZERO_LATENCY_IRQS)) {
+		__set_PRIMASK(mcu_critical_state);
+	} else {
+		irq_unlock(mcu_critical_state);
+	}
 }

 uint32_t z_nrf_rtc_timer_compare_evt_address_get(int32_t chan)
@ -93,25 +123,42 @@ uint32_t z_nrf_rtc_timer_compare_evt_address_get(int32_t chan)
 	return nrf_rtc_event_address_get(RTC, nrf_rtc_compare_event_get(chan));
 }

-bool z_nrf_rtc_timer_compare_int_lock(int32_t chan)
+static bool compare_int_lock(int32_t chan)
 {
-	__ASSERT_NO_MSG(chan && chan < CHAN_COUNT);
-
 	atomic_val_t prev = atomic_and(&int_mask, ~BIT(chan));

 	nrf_rtc_int_disable(RTC, RTC_CHANNEL_INT_MASK(chan));

+	__DMB();
+	__ISB();
+
 	return prev & BIT(chan);
 }

+
+bool z_nrf_rtc_timer_compare_int_lock(int32_t chan)
+{
+	__ASSERT_NO_MSG(chan && chan < CHAN_COUNT);
+
+	return compare_int_lock(chan);
+}
+
+static void compare_int_unlock(int32_t chan, bool key)
+{
+	if (key) {
+		atomic_or(&int_mask, BIT(chan));
+		nrf_rtc_int_enable(RTC, RTC_CHANNEL_INT_MASK(chan));
+		if (atomic_get(&force_isr_mask) & BIT(chan)) {
+			NVIC_SetPendingIRQ(RTC_IRQn);
+		}
+	}
+}
+
 void z_nrf_rtc_timer_compare_int_unlock(int32_t chan, bool key)
 {
 	__ASSERT_NO_MSG(chan && chan < CHAN_COUNT);

-	if (key) {
-		atomic_or(&int_mask, BIT(chan));
-		nrf_rtc_int_enable(RTC, RTC_CHANNEL_INT_MASK(chan));
-	}
+	compare_int_unlock(chan, key);
 }

 uint32_t z_nrf_rtc_timer_compare_read(int32_t chan)
@ -121,41 +168,48 @@ uint32_t z_nrf_rtc_timer_compare_read(int32_t chan)
 	return nrf_rtc_cc_get(RTC, chan);
 }

-int z_nrf_rtc_timer_get_ticks(k_timeout_t t)
+uint64_t z_nrf_rtc_timer_get_ticks(k_timeout_t t)
 {
-	uint32_t curr_count;
+	uint64_t curr_time;
 	int64_t curr_tick;
 	int64_t result;
 	int64_t abs_ticks;

 	do {
-		curr_count = counter();
+		curr_time = z_nrf_rtc_timer_read();
 		curr_tick = sys_clock_tick_get();
-	} while (curr_count != counter());
+	} while (curr_time != z_nrf_rtc_timer_read());

 	abs_ticks = Z_TICK_ABS(t.ticks);
 	if (abs_ticks < 0) {
 		/* relative timeout */
-		return (t.ticks > COUNTER_HALF_SPAN) ?
-			-EINVAL : ((curr_count + t.ticks) & COUNTER_MAX);
+		return (t.ticks > COUNTER_SPAN) ?
+			-EINVAL : (curr_time + t.ticks);
 	}

 	/* absolute timeout */
 	result = abs_ticks - curr_tick;

-	if ((result > COUNTER_HALF_SPAN) ||
-	    (result < -(int64_t)COUNTER_HALF_SPAN)) {
+	if (result > COUNTER_SPAN) {
 		return -EINVAL;
 	}

-	return (curr_count + result) & COUNTER_MAX;
+	return curr_time + result;
 }

-/* Function safely sets absolute alarm. It assumes that provided value is
- * less than COUNTER_HALF_SPAN from now. It detects late setting and also
- * handle +1 cycle case.
+/** @brief Function safely sets absolute alarm.
+ *
+ * It assumes that provided value is less than COUNTER_HALF_SPAN from now.
+ * It detects late setting and also handle +1 cycle case.
+ *
+ * @param[in] chan A channel for which a new CC value is to be set.
+ *
+ * @param[in] abs_val An absolute value of CC register to be set.
+ *
+ * @returns CC value that was actually set. It is equal to @p abs_val or
+ *  shifted ahead if @p abs_val was too near in the future (+1 case).
 */
-static void set_absolute_alarm(int32_t chan, uint32_t abs_val)
+static uint32_t set_absolute_alarm(int32_t chan, uint32_t abs_val)
 {
 	uint32_t now;
 	uint32_t now2;
@ -179,7 +233,6 @@ static void set_absolute_alarm(int32_t chan, uint32_t abs_val)
 			k_busy_wait(19);
 		}

-
 		/* If requested cc_val is in the past or next tick, set to 2
 		 * ticks from now. RTC may not generate event if CC is set for
 		 * 1 tick from now.
@ -202,39 +255,144 @@ static void set_absolute_alarm(int32_t chan, uint32_t abs_val)
 		 */
 	} while ((now2 != now) &&
 		 (counter_sub(cc_val, now2 + 2) > COUNTER_HALF_SPAN));
+
+	return cc_val;
 }

-static void compare_set(int32_t chan, uint32_t cc_value,
+static int compare_set_nolocks(int32_t chan, uint64_t target_time,
 			z_nrf_rtc_timer_compare_handler_t handler,
 			void *user_data)
 {
+	int ret = 0;
+	uint32_t cc_value = absolute_time_to_cc(target_time);
+	uint64_t curr_time = z_nrf_rtc_timer_read();
+
+	if (curr_time < target_time) {
+		if (target_time - curr_time > COUNTER_SPAN) {
+			/* Target time is too distant. */
+			return -EINVAL;
+		}
+
+		if (target_time != cc_data[chan].target_time) {
+			/* Target time is valid and is different than currently set.
+			 * Set CC value.
+			 */
+			uint32_t cc_set = set_absolute_alarm(chan, cc_value);
+
+			target_time += counter_sub(cc_set, cc_value);
+		}
+	} else {
+		/* Force ISR handling when exiting from critical section. */
+		atomic_or(&force_isr_mask, BIT(chan));
+	}
+
+	cc_data[chan].target_time = target_time;
 	cc_data[chan].callback = handler;
 	cc_data[chan].user_context = user_data;

-	set_absolute_alarm(chan, cc_value);
+	return ret;
 }

-void z_nrf_rtc_timer_compare_set(int32_t chan, uint32_t cc_value,
-			      z_nrf_rtc_timer_compare_handler_t handler,
-			      void *user_data)
+static int compare_set(int32_t chan, uint64_t target_time,
+			z_nrf_rtc_timer_compare_handler_t handler,
+			void *user_data)
+{
+	bool key;
+
+	key = compare_int_lock(chan);
+
+	int ret = compare_set_nolocks(chan, target_time, handler, user_data);
+
+	compare_int_unlock(chan, key);
+
+	return ret;
+}
+
+int z_nrf_rtc_timer_set(int32_t chan, uint64_t target_time,
+			 z_nrf_rtc_timer_compare_handler_t handler,
+			 void *user_data)
 {
 	__ASSERT_NO_MSG(chan && chan < CHAN_COUNT);

-	bool key = z_nrf_rtc_timer_compare_int_lock(chan);
+	return compare_set(chan, target_time, handler, user_data);
+}

-	compare_set(chan, cc_value, handler, user_data);
+void z_nrf_rtc_timer_abort(int32_t chan)
+{
+	__ASSERT_NO_MSG(chan && chan < CHAN_COUNT);

-	z_nrf_rtc_timer_compare_int_unlock(chan, key);
+	bool key = compare_int_lock(chan);
+
+	cc_data[chan].target_time = TARGET_TIME_INVALID;
+	event_clear(chan);
+	event_disable(chan);
+	(void)atomic_and(&force_isr_mask, ~BIT(chan));
+
+	compare_int_unlock(chan, key);
+}
+
+uint64_t z_nrf_rtc_timer_read(void)
+{
+	uint64_t val = ((uint64_t)overflow_cnt) << COUNTER_BIT_WIDTH;
+
+	__DMB();
+
+	uint32_t cntr = counter();
+
+	val += cntr;
+
+	if (cntr < OVERFLOW_RISK_RANGE_END) {
+		/* `overflow_cnt` can have incorrect value due to still unhandled overflow or
+		 * due to possibility that this code preempted overflow interrupt before final write
+		 * of `overflow_cnt`. Update of `anchor` occurs far in time from this moment, so
+		 * `anchor` is considered valid and stable. Because of this timing there is no risk
+		 * of incorrect `anchor` value caused by non-atomic read of 64-bit `anchor`.
+		 */
+		if (val < anchor) {
+			/* Unhandled overflow, detected, let's add correction */
+			val += COUNTER_SPAN;
+		}
+	} else {
+		/* `overflow_cnt` is considered valid and stable in this range, no need to
+		 * check validity using `anchor`
+		 */
+	}
+
+	return val;
+}
+
+static inline bool in_anchor_range(uint32_t cc_value)
+{
+	return (cc_value >= ANCHOR_RANGE_START) && (cc_value < ANCHOR_RANGE_END);
+}
+
+static inline bool anchor_update(uint32_t cc_value)
+{
+	/* Update anchor when far from overflow */
+	if (in_anchor_range(cc_value)) {
+		/* In this range `overflow_cnt` is considered valid and stable.
+		 * Write of 64-bit `anchor` is non atomic. However it happens
+		 * far in time from the moment the `anchor` is read in
+		 * `z_nrf_rtc_timer_read`.
+		 */
+		anchor = (((uint64_t)overflow_cnt) << COUNTER_BIT_WIDTH) + cc_value;
+		return true;
+	}
+
+	return false;
 }

 static void sys_clock_timeout_handler(int32_t chan,
-				      uint32_t cc_value,
+				      uint64_t expire_time,
 				      void *user_data)
 {
-	uint32_t dticks = counter_sub(cc_value, last_count) / CYC_PER_TICK;
+	uint32_t cc_value = absolute_time_to_cc(expire_time);
+	uint64_t dticks = (expire_time - last_count) / CYC_PER_TICK;

 	last_count += dticks * CYC_PER_TICK;

+	bool anchor_updated = anchor_update(cc_value);
+
 	if (!IS_ENABLED(CONFIG_TICKLESS_KERNEL)) {
 		/* protection is not needed because we are in the RTC interrupt
 		 * so it won't get preempted by the interrupt.
@ -244,7 +402,80 @@ static void sys_clock_timeout_handler(int32_t chan,
 	}

 	sys_clock_announce(IS_ENABLED(CONFIG_TICKLESS_KERNEL) ?
-						dticks : (dticks > 0));
+			   (int32_t)dticks : (dticks > 0));
+
+	if (cc_value == get_comparator(chan)) {
+		/* New value was not set. Set something that can update anchor.
+		 * If anchor was updated we can enable same CC value to trigger
+		 * interrupt after full cycle. Else set event in anchor update
+		 * range. Since anchor was not updated we know that it's very
+		 * far from mid point so setting is done without any protection.
+		 */
+		if (!anchor_updated) {
+			set_comparator(chan, COUNTER_HALF_SPAN);
+		}
+		event_enable(chan);
+	}
+}
+
+static bool channel_processing_check_and_clear(int32_t chan)
+{
+	bool result = false;
+
+	uint32_t mcu_critical_state = full_int_lock();
+
+	if (nrf_rtc_int_enable_check(RTC, RTC_CHANNEL_INT_MASK(chan))) {
+		/* The processing of channel can be caused by CC match
+		 * or be forced.
+		 */
+		result = atomic_and(&force_isr_mask, ~BIT(chan)) ||
+			 nrf_rtc_event_check(RTC, RTC_CHANNEL_EVENT_ADDR(chan));
+
+		if (result) {
+			event_clear(chan);
+		}
+	}
+
+	full_int_unlock(mcu_critical_state);
+
+	return result;
+}
+
+static void process_channel(int32_t chan)
+{
+	if (channel_processing_check_and_clear(chan)) {
+		void *user_context;
+		uint32_t mcu_critical_state;
+		uint64_t curr_time;
+		uint64_t expire_time;
+		z_nrf_rtc_timer_compare_handler_t handler = NULL;
+
+		curr_time = z_nrf_rtc_timer_read();
+
+		/* This critical section is used to provide atomic access to
+		 * cc_data structure and prevent higher priority contexts
+		 * (including ZLIs) from overwriting it.
+		 */
+		mcu_critical_state = full_int_lock();
+
+		/* If target_time is in the past or is equal to current time
+		 * value, execute the handler.
+		 */
+		expire_time = cc_data[chan].target_time;
+		if (curr_time >= expire_time) {
+			handler = cc_data[chan].callback;
+			user_context = cc_data[chan].user_context;
+			cc_data[chan].callback = NULL;
+			cc_data[chan].target_time = TARGET_TIME_INVALID;
+			event_disable(chan);
+		}
+
+		full_int_unlock(mcu_critical_state);
+
+		if (handler) {
+			handler(chan, expire_time, user_context);
+		}
+	}
 }

 /* Note: this function has public linkage, and MUST have this
@ -259,34 +490,14 @@ void rtc_nrf_isr(const void *arg)
 {
 	ARG_UNUSED(arg);

+	if (nrf_rtc_int_enable_check(RTC, NRF_RTC_INT_OVERFLOW_MASK) &&
+	    nrf_rtc_event_check(RTC, NRF_RTC_EVENT_OVERFLOW)) {
+		nrf_rtc_event_clear(RTC, NRF_RTC_EVENT_OVERFLOW);
+		overflow_cnt++;
+	}
+
 	for (int32_t chan = 0; chan < CHAN_COUNT; chan++) {
-		if (nrf_rtc_int_enable_check(RTC, RTC_CHANNEL_INT_MASK(chan)) &&
-		    nrf_rtc_event_check(RTC, RTC_CHANNEL_EVENT_ADDR(chan))) {
-			uint32_t cc_val;
-			uint32_t now;
-			z_nrf_rtc_timer_compare_handler_t handler;
-
-			event_clear(chan);
-			event_disable(chan);
-			cc_val = get_comparator(chan);
-			now = counter();
-
-			/* Higher priority interrupt may already changed cc_val
-			 * which now points to the future. In that case return
-			 * current counter value. It is less precise than
-			 * returning exact CC value but this one is already lost.
-			 */
-			if (counter_sub(now, cc_val) > COUNTER_HALF_SPAN) {
-				cc_val = now;
-			}
-
-			handler = cc_data[chan].callback;
-			cc_data[chan].callback = NULL;
-			if (handler) {
-				handler(chan, cc_val,
-					cc_data[chan].user_context);
-			}
-		}
+		process_channel(chan);
 	}
 }

@ -312,6 +523,7 @@ void z_nrf_rtc_timer_chan_free(int32_t chan)
 	atomic_or(&alloc_mask, BIT(chan));
 }

+
 void sys_clock_set_timeout(int32_t ticks, bool idle)
 {
 	ARG_UNUSED(idle);
@ -324,7 +536,7 @@ void sys_clock_set_timeout(int32_t ticks, bool idle)
 	ticks = (ticks == K_TICKS_FOREVER) ? MAX_TICKS : ticks;
 	ticks = CLAMP(ticks - 1, 0, (int32_t)MAX_TICKS);

-	uint32_t unannounced = counter_sub(counter(), last_count);
+	uint32_t unannounced = z_nrf_rtc_timer_read() - last_count;

 	/* If we haven't announced for more than half the 24-bit wrap
 	 * duration, then force an announce to avoid loss of a wrap
@ -349,8 +561,9 @@ void sys_clock_set_timeout(int32_t ticks, bool idle)
 		cyc = MAX_CYCLES;
 	}

-	cyc += last_count;
-	compare_set(0, cyc, sys_clock_timeout_handler, NULL);
+	uint64_t target_time = cyc + last_count;
+
+	compare_set(0, target_time, sys_clock_timeout_handler, NULL);
 }

 uint32_t sys_clock_elapsed(void)
@ -359,16 +572,12 @@ uint32_t sys_clock_elapsed(void)
 		return 0;
 	}

-	return counter_sub(counter(), last_count) / CYC_PER_TICK;
+	return (z_nrf_rtc_timer_read() - last_count) / CYC_PER_TICK;
 }

 uint32_t sys_clock_cycle_get_32(void)
 {
-	k_spinlock_key_t key = k_spin_lock(&lock);
-	uint32_t ret = counter_sub(counter(), last_count) + last_count;
-
-	k_spin_unlock(&lock, key);
-	return ret;
+	return (uint32_t)z_nrf_rtc_timer_read();
 }

 static int sys_clock_driver_init(const struct device *dev)
@ -384,9 +593,12 @@ static int sys_clock_driver_init(const struct device *dev)
 	/* TODO: replace with counter driver to access RTC */
 	nrf_rtc_prescaler_set(RTC, 0);
 	for (int32_t chan = 0; chan < CHAN_COUNT; chan++) {
+		cc_data[chan].target_time = TARGET_TIME_INVALID;
 		nrf_rtc_int_enable(RTC, RTC_CHANNEL_INT_MASK(chan));
 	}

+	nrf_rtc_int_enable(RTC, NRF_RTC_INT_OVERFLOW_MASK);
+
 	NVIC_ClearPendingIRQ(RTC_IRQn);

 	IRQ_CONNECT(RTC_IRQn, DT_IRQ(DT_NODELABEL(RTC_LABEL), priority),
@ -401,6 +613,12 @@ static int sys_clock_driver_init(const struct device *dev)
 		alloc_mask = BIT_MASK(EXT_CHAN_COUNT) << 1;
 	}

+	uint32_t initial_timeout = IS_ENABLED(CONFIG_TICKLESS_KERNEL) ?
+		(COUNTER_HALF_SPAN - 1) :
+		(counter() + CYC_PER_TICK);
+
+	compare_set(0, initial_timeout, sys_clock_timeout_handler, NULL);
+
 	if (!IS_ENABLED(CONFIG_TICKLESS_KERNEL)) {
 		compare_set(0, counter() + CYC_PER_TICK,
 			    sys_clock_timeout_handler, NULL);
--- a/include/drivers/timer/nrf_rtc_timer.h
+++ b/include/drivers/timer/nrf_rtc_timer.h
@ -11,8 +11,25 @@
 extern "C" {
 #endif

+/** @brief Maximum allowed time span that is considered to be in the future.
+ */
+#define NRF_RTC_TIMER_MAX_SCHEDULE_SPAN BIT(23)
+
+/** @brief RTC timer compare event handler.
+ *
+ * Called from RTC ISR context when processing a compare event.
+ *
+ * @param id Compare channel ID.
+ *
+ * @param expire_time An actual absolute expiration time set for a compare
+ *		      channel. It can differ from the requested target time
+ *		      and the difference can be used to determine whether the
+ *		      time set was delayed.
+ *
+ * @param user_data Pointer to a user context data.
+ */
 typedef void (*z_nrf_rtc_timer_compare_handler_t)(int32_t id,
-						uint32_t cc_value,
+						uint64_t expire_time,
 						void *user_data);

 /** @brief Allocate RTC compare channel.
@ -30,11 +47,11 @@ int32_t z_nrf_rtc_timer_chan_alloc(void);
 */
 void z_nrf_rtc_timer_chan_free(int32_t chan);

-/** @brief Read current RTC counter value.
+/** @brief Read current absolute time.
 *
- * @return Current RTC counter value.
+ * @return Current absolute time.
 */
-uint32_t z_nrf_rtc_timer_read(void);
+uint64_t z_nrf_rtc_timer_read(void);

 /** @brief Get COMPARE event register address.
 *
@ -76,38 +93,52 @@ uint32_t z_nrf_rtc_timer_compare_read(int32_t chan);

 /** @brief  Try to set compare channel to given value.
 *
- * Provided value is absolute and cannot be further in future than half span of
- * the RTC counter. Function continouosly retries to set compare register until
- * value that is written is far enough in the future and will generate an event.
- * Because of that, compare register value may be different than the one
- * requested. During this operation interrupt from that compare channel is
- * disabled. Other interrupts are not locked during this operation.
- *
- * There is no option to abort the request once it is set. However, it can be
- * overwritten.
+ * Provided value is absolute and cannot be further in the future than
+ * @c NRF_RTC_TIMER_MAX_SCHEDULE_SPAN. If given value is in the past then an RTC
+ * interrupt is triggered immediately. Otherwise function continuously retries
+ * to set compare register until value that is written is far enough in the
+ * future and will generate an event. Because of that, compare register value
+ * may be different than the one requested. During this operation interrupt
+ * from that compare channel is disabled. Other interrupts are not locked during
+ * this operation.
 *
 * @param chan Channel ID between 1 and CONFIG_NRF_RTC_TIMER_USER_CHAN_COUNT.
 *
- * @param cc_value Absolute value. Values which are further distanced from
- * current counter value than half RTC span are considered in the past.
+ * @param target_time Absolute target time in ticks.
 *
 * @param handler User function called in the context of the RTC interrupt.
 *
 * @param user_data Data passed to the handler.
+ *
+ * @retval 0 if the compare channel was set successfully.
+ * @retval -EINVAL if provided target time was further than
+ *         @c NRF_RTC_TIMER_MAX_SCHEDULE_SPAN ticks in the future.
 */
-void z_nrf_rtc_timer_compare_set(int32_t chan, uint32_t cc_value,
-			       z_nrf_rtc_timer_compare_handler_t handler,
-			       void *user_data);
+int z_nrf_rtc_timer_set(int32_t chan, uint64_t target_time,
+			 z_nrf_rtc_timer_compare_handler_t handler,
+			 void *user_data);
+
+/** @brief Abort a timer requested with @ref z_nrf_rtc_timer_set.
+ *
+ * If an abort operation is performed too late it is still possible for an event
+ * to fire. The user can detect a spurious event by comparing absolute time
+ * provided in callback and a result of @ref z_nrf_rtc_timer_read. During this
+ * operation interrupt from that compare channel is disabled. Other interrupts
+ * are not locked during this operation.
+ *
+ * @param chan Channel ID between 1 and CONFIG_NRF_RTC_TIMER_USER_CHAN_COUNT.
+ */
+void z_nrf_rtc_timer_abort(int32_t chan);

 /** @brief Convert system clock time to RTC ticks.
 *
- * @p t can be absolute or relative. @p t cannot be further from now than half
- * of the RTC range (e.g. 256 seconds if RTC is running at 32768 Hz).
+ * @p t can be absolute or relative. @p t cannot be further into the future
+ * from now than the RTC range (e.g. 512 seconds if RTC is running at 32768 Hz).
 *
 * @retval Positive value represents @p t in RTC tick value.
 * @retval -EINVAL if @p t is out of range.
 */
-int z_nrf_rtc_timer_get_ticks(k_timeout_t t);
+uint64_t z_nrf_rtc_timer_get_ticks(k_timeout_t t);

 #ifdef __cplusplus
 }
--- a/tests/drivers/timer/nrf_rtc_timer/src/main.c
+++ b/tests/drivers/timer/nrf_rtc_timer/src/main.c
@ -5,11 +5,12 @@
 */
 #include <ztest.h>
 #include <drivers/timer/nrf_rtc_timer.h>
+#include <hal/nrf_rtc.h>
 #include <hal/nrf_timer.h>
 #include <irq.h>

 struct test_data {
-	uint32_t cc_val;
+	uint64_t target_time;
 	uint32_t window;
 	uint32_t delay;
 	int err;
@ -53,18 +54,33 @@ static void stop_zli_timer0(void)
 	nrf_timer_task_trigger(NRF_TIMER0, NRF_TIMER_TASK_STOP);
 }

-static void timeout_handler(int32_t id, uint32_t cc_value, void *user_data)
+static void inject_overflow(void)
+{
+	/* Bump overflow counter by 100. */
+	uint32_t overflow_count = 100;
+
+	while (overflow_count--) {
+		nrf_rtc_task_trigger(NRF_RTC1, NRF_RTC_TASK_TRIGGER_OVERFLOW);
+		/* Wait for RTC counter to reach overflow from 0xFFFFF0 and
+		 * get handled.
+		 */
+		k_busy_wait(1000);
+	}
+}
+
+static void timeout_handler(int32_t id, uint64_t expire_time, void *user_data)
 {
 	struct test_data *data = user_data;
-	uint32_t now = z_nrf_rtc_timer_read();
-	uint32_t diff = (now - cc_value) & 0x00FFFFFF;
+	uint64_t now = z_nrf_rtc_timer_read();
+	uint64_t diff = (now - expire_time);

 	zassert_true(diff <= data->delay,
-		"Handler called in wrong time (%d), set cc: %d, got cc: %d",
-		now, data->cc_val, cc_value);
+		"Handler called in wrong time (%llu), set time: %llu, "
+		"got time: %llu",
+		now, data->target_time, expire_time);

-	if ((cc_value >= data->cc_val) &&
-	    (cc_value <= (data->cc_val + data->window))) {
+	if ((expire_time >= data->target_time) &&
+	    (expire_time <= (data->target_time + data->window))) {
 		data->err = 0;
 	}
 	timeout_handler_cnt++;
@ -72,15 +88,15 @@ static void timeout_handler(int32_t id, uint32_t cc_value, void *user_data)

 static void test_timeout(int32_t chan, k_timeout_t t, bool ext_window)
 {
-	int32_t cc_val = z_nrf_rtc_timer_get_ticks(t);
+	int64_t ticks = z_nrf_rtc_timer_get_ticks(t);
 	struct test_data test_data = {
-		.cc_val = cc_val,
+		.target_time = ticks,
 		.window = ext_window ? 100 : (Z_TICK_ABS(t.ticks) ? 0 : 32),
 		.delay = ext_window ? 100 : 2,
 		.err = -EINVAL
 	};

-	z_nrf_rtc_timer_compare_set(chan, cc_val, timeout_handler, &test_data);
+	z_nrf_rtc_timer_set(chan, (uint64_t)ticks, timeout_handler, &test_data);

 	/* wait additional arbitrary time. */
 	k_busy_wait(1000);
@ -130,10 +146,10 @@ static void test_z_nrf_rtc_timer_compare_evt_address_get(void)

 static void test_int_disable_enabled(void)
 {
-	uint32_t now = z_nrf_rtc_timer_read();
-	uint32_t t = 1000;
+	uint64_t now = z_nrf_rtc_timer_read();
+	uint64_t t = 1000;
 	struct test_data data = {
-		.cc_val = now + t,
+		.target_time = now + t,
 		.window = 1000,
 		.delay = 2000,
 		.err = -EINVAL
@ -144,7 +160,7 @@ static void test_int_disable_enabled(void)
 	chan = z_nrf_rtc_timer_chan_alloc();
 	zassert_true(chan >= 0, "Failed to allocate RTC channel.");

-	z_nrf_rtc_timer_compare_set(chan, data.cc_val, timeout_handler, &data);
+	z_nrf_rtc_timer_set(chan, data.target_time, timeout_handler, &data);

 	zassert_equal(data.err, -EINVAL, "Unexpected err: %d", data.err);
 	key = z_nrf_rtc_timer_compare_int_lock(chan);
@ -163,7 +179,7 @@ static void test_int_disable_enabled(void)
 static void test_get_ticks(void)
 {
 	k_timeout_t t = K_MSEC(1);
-	uint32_t exp_ticks = z_nrf_rtc_timer_read() + t.ticks;
+	uint64_t exp_ticks = z_nrf_rtc_timer_read() + t.ticks;
 	int ticks;

 	/* Relative 1ms from now timeout converted to RTC */
@ -186,20 +202,21 @@ static void test_get_ticks(void)
 		     "Unexpected result %d (expected: %d)", ticks, exp_ticks);

 	/* too far in the future */
-	t = Z_TIMEOUT_TICKS(sys_clock_tick_get() + 0x00800001);
+	t = Z_TIMEOUT_TICKS(sys_clock_tick_get() + 0x01000001);
 	ticks = z_nrf_rtc_timer_get_ticks(t);
 	zassert_equal(ticks, -EINVAL, "Unexpected ticks: %d", ticks);
 }


-static void sched_handler(int32_t id, uint32_t cc_val, void *user_data)
+static void sched_handler(int32_t id, uint64_t expire_time, void *user_data)
 {
 	int64_t now = sys_clock_tick_get();
 	int rtc_ticks_now =
 	     z_nrf_rtc_timer_get_ticks(Z_TIMEOUT_TICKS(Z_TICK_ABS(now)));
 	uint64_t *evt_uptime_us = user_data;

-	*evt_uptime_us = k_ticks_to_us_floor64(now - (rtc_ticks_now - cc_val));
+	*evt_uptime_us =
+	    k_ticks_to_us_floor64(now - (rtc_ticks_now - expire_time));
 }

 static void test_absolute_scheduling(void)
@ -208,7 +225,7 @@ static void test_absolute_scheduling(void)
 	int64_t now_us = k_ticks_to_us_floor64(sys_clock_tick_get());
 	uint64_t target_us = now_us + 5678;
 	uint64_t evt_uptime_us;
-	int rtc_ticks;
+	uint64_t rtc_ticks;
 	int32_t chan;

 	chan = z_nrf_rtc_timer_chan_alloc();
@ -216,10 +233,9 @@ static void test_absolute_scheduling(void)

 	/* schedule event in 5678us from now */
 	t = Z_TIMEOUT_TICKS(Z_TICK_ABS(K_USEC(target_us).ticks));
-	rtc_ticks = z_nrf_rtc_timer_get_ticks(t);
+	rtc_ticks = (uint64_t)z_nrf_rtc_timer_get_ticks(t);

-	z_nrf_rtc_timer_compare_set(chan, rtc_ticks,
-				  sched_handler, &evt_uptime_us);
+	z_nrf_rtc_timer_set(chan, rtc_ticks, sched_handler, &evt_uptime_us);

 	k_busy_wait(5678);

@ -230,10 +246,9 @@ static void test_absolute_scheduling(void)
 	/* schedule event now. */
 	now_us = k_ticks_to_us_floor64(sys_clock_tick_get());
 	t = Z_TIMEOUT_TICKS(Z_TICK_ABS(K_USEC(now_us).ticks));
-	rtc_ticks = z_nrf_rtc_timer_get_ticks(t);
+	rtc_ticks = (uint64_t)z_nrf_rtc_timer_get_ticks(t);

-	z_nrf_rtc_timer_compare_set(chan, rtc_ticks,
-				  sched_handler, &evt_uptime_us);
+	z_nrf_rtc_timer_set(chan, rtc_ticks, sched_handler, &evt_uptime_us);

 	k_busy_wait(200);

@ -289,7 +304,7 @@ static void test_stress(void)
 	z_nrf_rtc_timer_chan_free(chan);
 }

-static void test_reseting_cc(void)
+static void test_resetting_cc(void)
 {
 	uint32_t start = k_uptime_get_32();
 	uint32_t test_time = 1000;
@ -302,19 +317,18 @@ static void test_reseting_cc(void)
 	timeout_handler_cnt = 0;

 	do {
-		uint32_t now = z_nrf_rtc_timer_read();
+		uint64_t now = z_nrf_rtc_timer_read();
 		struct test_data test_data = {
-			.cc_val = now + 5,
+			.target_time = now + 5,
 			.window = 0,
 			.delay = 0,
 			.err = -EINVAL
 		};

-		/* Set compare but expect that it will never expire because
+		/* Set timer but expect that it will never expire because
 		 * it will be later on reset.
 		 */
-		z_nrf_rtc_timer_compare_set(chan, now + 2,
-					    timeout_handler, &test_data);
+		z_nrf_rtc_timer_set(chan, now + 2, timeout_handler, &test_data);

 		/* Arbitrary variable delay to reset CC before expiring first
 		 * request but very close.
@ -322,8 +336,7 @@ static void test_reseting_cc(void)
 		k_busy_wait(i);
 		i = (i + 1) % 20;

-		z_nrf_rtc_timer_compare_set(chan, now + 5,
-					    timeout_handler, &test_data);
+		z_nrf_rtc_timer_set(chan, now + 5, timeout_handler, &test_data);
 		k_busy_wait((5 + 1)*31);
 		cnt++;
 	} while ((k_uptime_get_32() - start) < test_time);
@ -334,6 +347,86 @@ static void test_reseting_cc(void)
 	z_nrf_rtc_timer_chan_free(chan);
 }

+static void overflow_sched_handler(int32_t id, uint64_t expire_time,
+				   void *user_data)
+{
+	uint64_t now = z_nrf_rtc_timer_read();
+	uint64_t *evt_uptime = user_data;
+
+	*evt_uptime = now - expire_time;
+}
+
+/* This test is to be executed as the last, due to interference in overflow
+ * counter, resulting in nRF RTC timer ticks and kernel ticks desynchronization.
+ */
+static void test_overflow(void)
+{
+	PRINT("RTC ticks before overflow injection: %u\r\n",
+	      (uint32_t)z_nrf_rtc_timer_read());
+
+	inject_overflow();
+
+	PRINT("RTC ticks after overflow injection: %u\r\n",
+	      (uint32_t)z_nrf_rtc_timer_read());
+
+	uint64_t now;
+	uint64_t target_time;
+	uint64_t evt_uptime;
+	int32_t chan;
+
+	chan = z_nrf_rtc_timer_chan_alloc();
+	zassert_true(chan >= 0, "Failed to allocate RTC channel.");
+
+	/* Schedule event in 5 ticks from now. */
+	evt_uptime = UINT64_MAX;
+	now = z_nrf_rtc_timer_read();
+	target_time = now + 5;
+	z_nrf_rtc_timer_set(chan, target_time, overflow_sched_handler,
+			    &evt_uptime);
+
+	k_busy_wait(k_ticks_to_us_floor64(5 + 1));
+
+	PRINT("RTC event scheduled at %llu ticks for %llu ticks,"
+	      "event occurred at %llu ticks (uptime)\n",
+	      now, target_time, evt_uptime);
+	zassert_not_equal(UINT64_MAX, evt_uptime,
+			  "Expired timer shall overwrite evt_uptime");
+
+	/* Schedule event now. */
+	evt_uptime = UINT64_MAX;
+	now = z_nrf_rtc_timer_read();
+	target_time = now;
+
+	z_nrf_rtc_timer_set(chan, target_time, overflow_sched_handler,
+			    &evt_uptime);
+
+	k_busy_wait(200);
+
+	zassert_not_equal(UINT64_MAX, evt_uptime,
+			  "Expired timer shall overwrite evt_uptime");
+	PRINT("RTC event scheduled at %llu ticks for %llu ticks,"
+	      "event occurred at %llu ticks (uptime)\n",
+	      now, target_time, evt_uptime);
+
+	/* Schedule event far in the past. */
+	evt_uptime = UINT64_MAX;
+	now = z_nrf_rtc_timer_read();
+	target_time = now - 2 * NRF_RTC_TIMER_MAX_SCHEDULE_SPAN;
+
+	z_nrf_rtc_timer_set(chan, target_time, overflow_sched_handler,
+			    &evt_uptime);
+
+	k_busy_wait(200);
+
+	zassert_not_equal(UINT64_MAX, evt_uptime,
+			  "Expired timer shall overwrite evt_uptime");
+	PRINT("RTC event scheduled at %llu ticks for %llu ticks,"
+	      "event occurred at %llu ticks (uptime)\n",
+	      now, target_time, evt_uptime);
+
+	z_nrf_rtc_timer_chan_free(chan);
+}
+
 void test_main(void)
 {
 	init_zli_timer0();
@ -346,7 +439,8 @@ void test_main(void)
 		ztest_unit_test(test_absolute_scheduling),
 		ztest_unit_test(test_alloc_free),
 		ztest_unit_test(test_stress),
-		ztest_unit_test(test_reseting_cc)
+		ztest_unit_test(test_resetting_cc),
+		ztest_unit_test(test_overflow)
 			 );
 	ztest_run_test_suite(test_nrf_rtc_timer);
 }