On 24/08/2021 11:09, Finn Thain wrote:
Signed-off-by: Finn Thain <fth...@linux-m68k.org>
---
hw/misc/mos6522.c | 19 ++++++++++++-------
include/hw/misc/mos6522.h | 3 +++
2 files changed, 15 insertions(+), 7 deletions(-)
diff --git a/hw/misc/mos6522.c b/hw/misc/mos6522.c
index ffff8991f4..5b1657ac0d 100644
--- a/hw/misc/mos6522.c
+++ b/hw/misc/mos6522.c
@@ -79,6 +79,7 @@ static void set_counter(MOS6522State *s, MOS6522Timer *ti,
unsigned int val)
trace_mos6522_set_counter(1 + ti->index, val);
ti->load_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
ti->counter_value = val;
+ ti->oneshot_fired = false;
if (ti->index == 0) {
mos6522_timer1_update(s, ti, ti->load_time);
} else {
@@ -133,7 +134,8 @@ static void mos6522_timer1_update(MOS6522State *s,
MOS6522Timer *ti,
return;
}
ti->next_irq_time = get_next_irq_time(s, ti, current_time);
- if ((s->ier & T1_INT) == 0 || (s->acr & T1MODE) != T1MODE_CONT) {
+ if ((s->ier & T1_INT) == 0 ||
+ ((s->acr & T1MODE) == T1MODE_ONESHOT && ti->oneshot_fired)) {
timer_del(ti->timer);
} else {
timer_mod(ti->timer, ti->next_irq_time);
@@ -147,7 +149,7 @@ static void mos6522_timer2_update(MOS6522State *s,
MOS6522Timer *ti,
return;
}
ti->next_irq_time = get_next_irq_time(s, ti, current_time);
- if ((s->ier & T2_INT) == 0) {
+ if ((s->ier & T2_INT) == 0 || (s->acr & T2MODE) || ti->oneshot_fired) {
timer_del(ti->timer);
} else {
timer_mod(ti->timer, ti->next_irq_time);
@@ -159,6 +161,7 @@ static void mos6522_timer1_expired(void *opaque)
MOS6522State *s = opaque;
MOS6522Timer *ti = &s->timers[0];
+ ti->oneshot_fired = true;
mos6522_timer1_update(s, ti, ti->next_irq_time);
s->ifr |= T1_INT;
mos6522_update_irq(s);
@@ -169,6 +172,7 @@ static void mos6522_timer2_expired(void *opaque)
MOS6522State *s = opaque;
MOS6522Timer *ti = &s->timers[1];
+ ti->oneshot_fired = true;
mos6522_timer2_update(s, ti, ti->next_irq_time);
s->ifr |= T2_INT;
mos6522_update_irq(s);
I was trying to understand why you need ti->oneshot_fired here since the
mos6522_timer*_update() functions should simply not re-arm the timer if not in
continuous mode...
@@ -198,10 +202,12 @@ uint64_t mos6522_read(void *opaque, hwaddr addr, unsigned
size)
int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
if (now >= s->timers[0].next_irq_time) {
+ s->timers[0].oneshot_fired = true;
mos6522_timer1_update(s, &s->timers[0], now);
s->ifr |= T1_INT;
}
if (now >= s->timers[1].next_irq_time) {
+ s->timers[1].oneshot_fired = true;
mos6522_timer2_update(s, &s->timers[1], now);
s->ifr |= T2_INT;
}
...however this block above raises the timer interrupt outside of the timer callback.
This block isn't part of your original patch but was introduced as part of
cd8843ff25d ("mos6522: fix T1 and T2 timers") but I'm wondering if it is wrong.
If you remove both of the above if (now ... ) {} blocks then does one-shot mode work
by just adding the (s->acr & T2MODE) check in mos6522_timer2_update()? I'm guessing
that Linux/m68k does use one or both of the timers in one-shot mode?
@@ -279,6 +285,7 @@ void mos6522_write(void *opaque, hwaddr addr, uint64_t val,
unsigned size)
{
MOS6522State *s = opaque;
MOS6522DeviceClass *mdc = MOS6522_GET_CLASS(s);
+ int64_t now;
trace_mos6522_write(addr, val);
@@ -318,9 +325,6 @@ void mos6522_write(void *opaque, hwaddr addr, uint64_t val, unsigned size)
s->timers[1].latch = (s->timers[1].latch & 0xff00) | val;
break;
case VIA_REG_T2CH:
- /* To ensure T2 generates an interrupt on zero crossing with the
- common timer code, write the value directly from the latch to
- the counter */
s->timers[1].latch = (s->timers[1].latch & 0xff) | (val << 8);
s->ifr &= ~T2_INT;
set_counter(s, &s->timers[1], s->timers[1].latch);
@@ -330,8 +334,9 @@ void mos6522_write(void *opaque, hwaddr addr, uint64_t val,
unsigned size)
break;
case VIA_REG_ACR:
s->acr = val;
- mos6522_timer1_update(s, &s->timers[0],
- qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
+ now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+ mos6522_timer1_update(s, &s->timers[0], now);
+ mos6522_timer2_update(s, &s->timers[1], now);
break;
case VIA_REG_PCR:
s->pcr = val;
diff --git a/include/hw/misc/mos6522.h b/include/hw/misc/mos6522.h
index fc95d22b0f..94b1dc324c 100644
--- a/include/hw/misc/mos6522.h
+++ b/include/hw/misc/mos6522.h
@@ -50,8 +50,10 @@
#define T1_INT 0x40 /* Timer 1 interrupt */
/* Bits in ACR */
+#define T2MODE 0x20 /* Timer 2 mode */
#define T1MODE 0xc0 /* Timer 1 mode */
#define T1MODE_CONT 0x40 /* continuous interrupts */
+#define T1MODE_ONESHOT 0x00 /* timed interrupt */
/* VIA registers */
#define VIA_REG_B 0x00
@@ -83,6 +85,7 @@ typedef struct MOS6522Timer {
int64_t next_irq_time;
uint64_t frequency;
QEMUTimer *timer;
+ bool oneshot_fired;
} MOS6522Timer;
/**
ATB,
Mark.
