void
os_tick_idle(os_time_t ticks)
{
uint32_t ocmp;
OS_ASSERT_CRITICAL();
if (ticks > 0) {
/*
* Enter tickless regime during long idle durations.
*/
if (ticks > g_hal_os_tick.max_idle_ticks) {
ticks = g_hal_os_tick.max_idle_ticks;
}
ocmp = g_hal_os_tick.lastocmp + (ticks*g_hal_os_tick.ticks_per_ostick);
nrf52_os_tick_set_ocmp(ocmp);
}
__DSB();
__WFI();
if (ticks > 0) {
/*
* Update OS time before anything else when coming out of
* the tickless regime.
*/
nrf52_timer_handler();
}
}
static inline void
nrf52_os_tick_set_ocmp(uint32_t ocmp)
{
int delta;
uint32_t counter;
OS_ASSERT_CRITICAL();
while (1) {
ocmp &= 0xffffff;
OS_TICK_TIMER->CC[OS_TICK_CMPREG] = ocmp;
counter = nrf52_os_tick_counter();
/*
* From nRF52 Product specification
*
* - If Counter is 'N' writing (N) or (N + 1) to CC register
* may not trigger a compare event.
*
* - If Counter is 'N' writing (N + 2) to CC register is guaranteed
* to trigger a compare event at 'N + 2'.
*/
delta = sub24(ocmp, counter);
if (delta > 2) {
break;
}
ocmp += g_hal_os_tick.ticks_per_ostick;
}
}
void
os_tick_idle(os_time_t ticks)
{
OS_ASSERT_CRITICAL();
__DSB();
__WFI();
}
static void
apollo2_os_tick_set_timer(int os_ticks)
{
uint32_t sys_ticks;
uint32_t cfg;
OS_ASSERT_CRITICAL();
sys_ticks = os_ticks * apollo2_os_tick_dur;
/* Freeze time, set timer expiry, then unfreeze time. */
cfg = am_hal_stimer_config(AM_HAL_STIMER_CFG_FREEZE);
am_hal_stimer_compare_delta_set(0, sys_ticks);
am_hal_stimer_config(cfg);
}
static inline uint32_t
nrf52_os_tick_counter(void)
{
/*
* Make sure we are not interrupted between invoking the capture task
* and reading the value.
*/
OS_ASSERT_CRITICAL();
#if defined(BSP_HAS_32768_XTAL)
return OS_TICK_TIMER->COUNTER;
#else
/*
* Capture the current timer value and return it.
*/
OS_TICK_TIMER->TASKS_CAPTURE[OS_TICK_COUNTER] = 1;
return (OS_TICK_TIMER->CC[OS_TICK_COUNTER]);
#endif
}
void
os_tick_idle(os_time_t ticks)
{
OS_ASSERT_CRITICAL();
/* Since the STIMER only uses relative scheduling, all ticks values are
* valid. There is no need to check for wrap around.
*/
/* Only set the timer for nonzero tick values. For values of 0, just let
* the timer expire on the next tick, as scheduled earlier.
*/
if (ticks > 0) {
apollo2_os_tick_set_timer(ticks);
}
__DSB();
__WFI();
if (ticks > 0) {
apollo2_os_tick_handler();
}
}
