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[Qemu-devel] [PULL 17/28] hw/ptimer: Perform counter wrap around if time
From: |
Peter Maydell |
Subject: |
[Qemu-devel] [PULL 17/28] hw/ptimer: Perform counter wrap around if timer already expired |
Date: |
Mon, 6 Jun 2016 15:47:34 +0100 |
From: Dmitry Osipenko <address@hidden>
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 <address@hidden>
Reviewed-by: Peter Crosthwaite <address@hidden>
Message-id: address@hidden
Signed-off-by: Peter Maydell <address@hidden>
---
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;
--
1.9.1
[Qemu-devel] [PULL 19/28] hw/ptimer: Support "on the fly" timer mode switch, Peter Maydell, 2016/06/06
[Qemu-devel] [PULL 11/28] hw/arm/virt: Reject gic-version=host for non-KVM, Peter Maydell, 2016/06/06
[Qemu-devel] [PULL 06/28] target-arm: kvm64: set guest PMUv3 feature bit if supported, Peter Maydell, 2016/06/06
[Qemu-devel] [PULL 09/28] hw/intc/gic: RAZ/WI non-sec access to sec interrupts, Peter Maydell, 2016/06/06
[Qemu-devel] [PULL 26/28] char: get rid of qemu_char_get_next_serial, Peter Maydell, 2016/06/06