/**
*
* @brief Initialize and enable the system clock
*
* This routine is used to program the timer to deliver interrupts at the
* rate specified via the 'sys_clock_us_per_tick' global variable.
*
* @return 0
*/
int _sys_clock_driver_init(struct device *device)
{
ARG_UNUSED(device);
/* determine the timer counter value (in timer clock cycles/system tick)
*/
cycles_per_tick = sys_clock_hw_cycles_per_tick;
tickless_idle_init();
#ifndef CONFIG_MVIC
divide_configuration_register_set();
#endif
initial_count_register_set(cycles_per_tick - 1);
periodic_mode_set();
#ifdef CONFIG_DEVICE_POWER_MANAGEMENT
loapic_timer_device_power_state = DEVICE_PM_ACTIVE_STATE;
#endif
IRQ_CONNECT(TIMER_IRQ, TIMER_IRQ_PRIORITY, _timer_int_handler, 0, 0);
/* Everything has been configured. It is now safe to enable the
* interrupt
*/
irq_enable(TIMER_IRQ);
return 0;
}
/**
*
* @brief Initialize and enable the system clock
*
* This routine is used to program the timer to deliver interrupts at the
* rate specified via the 'sys_clock_us_per_tick' global variable.
*
* @return 0
*/
int _sys_clock_driver_init(struct device *device)
{
ARG_UNUSED(device);
/* determine the timer counter value (in timer clock cycles/system tick)
*/
cycles_per_tick = sys_clock_hw_cycles_per_tick;
tickless_idle_init();
divide_configuration_register_set();
initial_count_register_set(cycles_per_tick - 1);
periodic_mode_set();
IRQ_CONNECT(CONFIG_LOAPIC_TIMER_IRQ, CONFIG_LOAPIC_TIMER_IRQ_PRIORITY,
_timer_int_handler, 0, 0);
/* Everything has been configured. It is now safe to enable the
* interrupt
*/
irq_enable(CONFIG_LOAPIC_TIMER_IRQ);
return 0;
}
void _timer_int_handler(void *unused /* parameter is not used */
)
{
ARG_UNUSED(unused);
#ifdef CONFIG_TICKLESS_IDLE
if (timer_mode == TIMER_MODE_ONE_SHOT) {
if (!timer_known_to_have_expired) {
uint32_t cycles;
/*
* The timer fired unexpectedly. This is due to one of two cases:
* 1. Entering tickless idle straddled a tick.
* 2. Leaving tickless idle straddled the final tick.
* Due to the timer reprogramming in _timer_idle_exit(), case #2
* can be handled as a fall-through.
*
* NOTE: Although the cycle count is supposed to stop decrementing
* once it hits zero in one-shot mode, not all targets implement
* this properly (and continue to decrement). Thus, we have to
* perform a second comparison to check for wrap-around.
*/
cycles = current_count_register_get();
if ((cycles > 0) && (cycles < programmed_cycles)) {
/* Case 1 */
_sys_idle_elapsed_ticks = 0;
}
}
/* Return the timer to periodic mode */
initial_count_register_set(cycles_per_tick - 1);
periodic_mode_set();
timer_known_to_have_expired = false;
timer_mode = TIMER_MODE_PERIODIC;
}
_sys_clock_final_tick_announce();
/* track the accumulated cycle count */
accumulated_cycle_count += cycles_per_tick * _sys_idle_elapsed_ticks;
#else
/* track the accumulated cycle count */
accumulated_cycle_count += cycles_per_tick;
_sys_clock_tick_announce();
#endif /*CONFIG_TICKLESS_IDLE*/
}
/**
*
* @brief System clock tick handler
*
* This routine handles the system clock tick interrupt. A TICK_EVENT event
* is pushed onto the microkernel stack.
*
* @return N/A
*/
void _timer_int_handler(void *unused /* parameter is not used */
)
{
ARG_UNUSED(unused);
#ifdef CONFIG_TICKLESS_IDLE
if (timer_mode == TIMER_MODE_ONE_SHOT) {
if (!timer_known_to_have_expired) {
uint32_t cycles;
/*
* The timer fired unexpectedly. This is due to one of two cases:
* 1. Entering tickless idle straddled a tick.
* 2. Leaving tickless idle straddled the final tick.
* Due to the timer reprogramming in _timer_idle_exit(), case #2
* can be handled as a fall-through.
*
* NOTE: Although the cycle count is supposed to stop decrementing
* once it hits zero in one-shot mode, not all targets implement
* this properly (and continue to decrement). Thus, we have to
* perform a second comparison to check for wrap-around.
*/
cycles = current_count_register_get();
if ((cycles > 0) && (cycles < programmed_cycles)) {
/* Case 1 */
_sys_idle_elapsed_ticks = 0;
}
}
/* Return the timer to periodic mode */
initial_count_register_set(cycles_per_tick - 1);
periodic_mode_set();
timer_known_to_have_expired = false;
timer_mode = TIMER_MODE_PERIODIC;
}
/*
* Increment the tick because _timer_idle_exit() does not account
* for the tick due to the timer interrupt itself. Also, if not in
* one-shot mode, _sys_idle_elapsed_ticks will be 0.
*/
#ifdef CONFIG_MICROKERNEL
_sys_idle_elapsed_ticks++;
#else
_sys_idle_elapsed_ticks = 1;
#endif
/* track the accumulated cycle count */
accumulated_cycle_count += cycles_per_tick * _sys_idle_elapsed_ticks;
/*
* If we transistion from 0 elapsed ticks to 1 we need to announce the
* tick event to the microkernel. Other cases will have already been
* covered by _timer_idle_exit().
*/
if (_sys_idle_elapsed_ticks == 1) {
_sys_clock_tick_announce();
}
#else
/* track the accumulated cycle count */
accumulated_cycle_count += cycles_per_tick;
_sys_clock_tick_announce();
#endif /*CONFIG_TICKLESS_IDLE*/
#ifdef LOAPIC_TIMER_PERIODIC_WORKAROUND
/*
* On platforms where the LOAPIC timer periodic mode is broken,
* re-program the ICR register with the initial count value. This
* is only a temporary workaround.
*/
initial_count_register_set(cycles_per_tick - 1);
periodic_mode_set();
#endif /* LOAPIC_TIMER_PERIODIC_WORKAROUND */
}
