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drivers: nrf_rtc_timer: Simplify sys_clock_set_timeout calculations

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Remove unnecessary decreasing of the number of ticks by 1 (it was then
increased by 1 when it was converted to the number of cycles) and add
a comment that clarifies the way that ticks < 1 are handled.

Signed-off-by: Andrzej Głąbek <andrzej.glabek@nordicsemi.no>
This commit is contained in:
Andrzej Głąbek 2023-01-02 09:35:58 +01:00 • committed by Carles Cufí
commit bf1d3db1d4
1 changed files with 15 additions and 10 deletions
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25
drivers/timer/nrf_rtc_timer.c
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@ -11,6 +11,7 @@
#include <zephyr/drivers/clock_control/nrf_clock_control.h>
#include <zephyr/drivers/timer/system_timer.h>
#include <zephyr/drivers/timer/nrf_rtc_timer.h>
#include <zephyr/sys/util.h>
#include <zephyr/sys_clock.h>
#include <hal/nrf_rtc.h>
#include <zephyr/irq.h>
@ -592,12 +593,17 @@ void sys_clock_set_timeout(int32_t ticks, bool idle)
return;
}
ticks = (ticks == K_TICKS_FOREVER) ? MAX_TICKS : ticks;
ticks = CLAMP(ticks - 1, 0, (int32_t)MAX_TICKS);
/* If timeout is set to max we assume that system is idle and timeout
* is set to forever.
*/
sys_busy = (ticks < (MAX_TICKS - 1));
if (ticks == K_TICKS_FOREVER) {
cyc = MAX_TICKS * CYC_PER_TICK;
sys_busy = false;
} else {
/* Value of ticks can be zero or negative, what means "announce
* the next tick" (the same as ticks equal to 1).
*/
cyc = CLAMP(ticks, 1, (int32_t)MAX_TICKS);
cyc *= CYC_PER_TICK;
sys_busy = true;
}
uint32_t unannounced = z_nrf_rtc_timer_read() - last_count;
@ -607,15 +613,14 @@ void sys_clock_set_timeout(int32_t ticks, bool idle)
* before the existing one triggers the interrupt.
*/
if (unannounced >= COUNTER_HALF_SPAN) {
ticks = 0;
cyc = 0;
}
/* Get the cycles from last_count to the tick boundary after
* the requested ticks have passed starting now.
*/
cyc = ticks * CYC_PER_TICK + 1 + unannounced;
cyc += (CYC_PER_TICK - 1);
cyc = (cyc / CYC_PER_TICK) * CYC_PER_TICK;
cyc += unannounced;
cyc = ceiling_fraction(cyc, CYC_PER_TICK) * CYC_PER_TICK;
/* Due to elapsed time the calculation above might produce a
* duration that laps the counter. Don't let it.