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drivers: timer: nrf_rtc_timer: Optimize z_nrf_rtc_timer_get_ticks

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Converting absolute system ticks to RTC ticks is simple. It needs to be
multiplied by CYC_PER_TICK (which by default is 1). Complex algorithm
was used when driver was not tracking current 64 bit tick and function
was returning uint32_t.

Signed-off-by: Krzysztof Chruściński <krzysztof.chruscinski@nordicsemi.no>
This commit is contained in:
Krzysztof Chruściński 2025-01-15 11:00:02 +01:00 • committed by Dan Kalowsky
commit 6717a37421
2 changed files with 9 additions and 15 deletions
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21
drivers/timer/nrf_rtc_timer.c
View file

@ -197,30 +197,25 @@ uint32_t z_nrf_rtc_timer_compare_read(int32_t chan)
uint64_t z_nrf_rtc_timer_get_ticks(k_timeout_t t)
{
uint64_t curr_time;
int64_t curr_tick;
int64_t result;
int64_t abs_ticks;
do {
curr_time = z_nrf_rtc_timer_read();
curr_tick = sys_clock_tick_get();
} while (curr_time != z_nrf_rtc_timer_read());
abs_ticks = Z_TICK_ABS(t.ticks);
if (Z_IS_TIMEOUT_RELATIVE(t)) {
return (t.ticks > COUNTER_SPAN) ?
-EINVAL : (curr_time + t.ticks);
-EINVAL : (z_nrf_rtc_timer_read() + t.ticks * CYC_PER_TICK);
}
/* absolute timeout */
result = abs_ticks - curr_tick;
if (result > COUNTER_SPAN) {
/* abs_ticks is int64_t so it has 63 bits. If CYC_PER_TICK is <=2 then
* any abs_ticks will fit in 64 bits after multiplying by CYC_PER_TICK
* but if CYC_PER_TICK is higher then it is possible that abs_ticks cannot
* be converted to RTC ticks and check for overflow is needed.
*/
if ((CYC_PER_TICK > 2) && (abs_ticks > (UINT64_MAX / CYC_PER_TICK))) {
return -EINVAL;
}
return curr_time + result;
return abs_ticks * CYC_PER_TICK;
}
/** @brief Function safely sets an alarm.

3
include/zephyr/drivers/timer/nrf_rtc_timer.h
View file

@ -177,8 +177,7 @@ 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 into the future
* from now than the RTC range (e.g. 512 seconds if RTC is running at 32768 Hz).
* @p t can be absolute or relative.
*
* @retval Positive value represents @p t in RTC tick value.
* @retval -EINVAL if @p t is out of range.