static void hpet_set_timer(HPETState *h, unsigned int tn)
{
uint64_t tn_cmp, cur_tick, diff;
unsigned int irq;
unsigned int oneshot;
ASSERT(tn < HPET_TIMER_NUM);
ASSERT(spin_is_locked(&h->lock));
if ( (tn == 0) && (h->hpet.config & HPET_CFG_LEGACY) )
{
/* HPET specification requires PIT shouldn't generate
* interrupts if LegacyReplacementRoute is set for timer0 */
PITState *pit = &vhpet_domain(h)->arch.hvm_domain.pl_time.vpit;
pit_stop_channel0_irq(pit);
}
if ( !timer_enabled(h, tn) )
return;
tn_cmp = hpet_get_comparator(h, tn);
cur_tick = hpet_read_maincounter(h);
if ( timer_is_32bit(h, tn) )
{
tn_cmp = (uint32_t)tn_cmp;
cur_tick = (uint32_t)cur_tick;
}
diff = tn_cmp - cur_tick;
/*
* Detect time values set in the past. This is hard to do for 32-bit
* comparators as the timer does not have to be set that far in the future
* for the counter difference to wrap a 32-bit signed integer. We fudge
* by looking for a 'small' time value in the past.
*/
if ( (int64_t)diff < 0 )
diff = (timer_is_32bit(h, tn) && (-diff > HPET_TINY_TIME_SPAN))
? (uint32_t)diff : 0;
if ( (tn <= 1) && (h->hpet.config & HPET_CFG_LEGACY) )
/* if LegacyReplacementRoute bit is set, HPET specification requires
timer0 be routed to IRQ0 in NON-APIC or IRQ2 in the I/O APIC,
timer1 be routed to IRQ8 in NON-APIC or IRQ8 in the I/O APIC. */
irq = (tn == 0) ? 0 : 8;
else
irq = timer_int_route(h, tn);
/*
* diff is the time from now when the timer should fire, for a periodic
* timer we also need the period which may be different because time may
* have elapsed between the time the comparator was written and the timer
* being enabled (now).
*/
oneshot = !timer_is_periodic(h, tn);
create_periodic_time(vhpet_vcpu(h), &h->pt[tn],
hpet_tick_to_ns(h, diff),
oneshot ? 0 : hpet_tick_to_ns(h, h->hpet.period[tn]),
irq, NULL, NULL);
}
static uint64_t hpet_get_comparator(HPETState *h, unsigned int tn)
{
uint64_t comparator;
uint64_t elapsed;
comparator = h->hpet.comparator64[tn];
if ( timer_is_periodic(h, tn) )
{
/* update comparator by number of periods elapsed since last update */
uint64_t period = h->hpet.period[tn];
if (period)
{
elapsed = hpet_read_maincounter(h) + period - 1 - comparator;
comparator += (elapsed / period) * period;
h->hpet.comparator64[tn] = comparator;
}
}
/* truncate if timer is in 32 bit mode */
if ( timer_is_32bit(h, tn) )
comparator = (uint32_t)comparator;
h->hpet.timers[tn].cmp = comparator;
return comparator;
}
