From 5a50307b48f834d0048fde20aa6c0e24cd9f33be Mon Sep 17 00:00:00 2001 From: Dmitry Osipenko Date: Mon, 6 Jun 2016 16:59:30 +0100 Subject: hw/ptimer: Perform counter wrap around if timer already expired ptimer_get_count() might be called while QEMU timer already been expired. In that case ptimer would return counter = 0, which might be undesirable in case of polled timer. Do counter wrap around for periodic timer to keep it distributed. In order to achieve more accurate emulation behaviour of certain hardware, don't perform wrap around when in icount mode and return counter = 0 in that case (that doesn't affect polled counter distribution). Signed-off-by: Dmitry Osipenko Reviewed-by: Peter Crosthwaite Message-id: 4ce381c7d24d85d165ff251d2875d16a4b6a5c04.1464367869.git.digetx@gmail.com Signed-off-by: Peter Maydell --- hw/core/ptimer.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/hw/core/ptimer.c b/hw/core/ptimer.c index 16d7dd5..7e6fc2d 100644 --- a/hw/core/ptimer.c +++ b/hw/core/ptimer.c @@ -84,14 +84,16 @@ static void ptimer_tick(void *opaque) uint64_t ptimer_get_count(ptimer_state *s) { - int64_t now; uint64_t counter; if (s->enabled) { - now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); + int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); + int64_t next = s->next_event; + bool expired = (now - next >= 0); + bool oneshot = (s->enabled == 2); + /* Figure out the current counter value. */ - if (now - s->next_event > 0 - || s->period == 0) { + if (s->period == 0 || (expired && (oneshot || use_icount))) { /* Prevent timer underflowing if it should already have triggered. */ counter = 0; @@ -103,7 +105,7 @@ uint64_t ptimer_get_count(ptimer_state *s) uint32_t period_frac = s->period_frac; uint64_t period = s->period; - if ((s->enabled == 1) && !use_icount && (s->delta * period < 10000)) { + if (!oneshot && (s->delta * period < 10000) && !use_icount) { period = 10000 / s->delta; period_frac = 0; } @@ -118,7 +120,7 @@ uint64_t ptimer_get_count(ptimer_state *s) backwards. */ - rem = s->next_event - now; + rem = expired ? now - next : next - now; div = period; clz1 = clz64(rem); @@ -138,6 +140,11 @@ uint64_t ptimer_get_count(ptimer_state *s) div += 1; } counter = rem / div; + + if (expired && counter != 0) { + /* Wrap around periodic counter. */ + counter = s->limit - (counter - 1) % s->limit; + } } } else { counter = s->delta; -- cgit v1.1