From bd54c25035217800f3b1d39f6472d599cd602d5a Mon Sep 17 00:00:00 2001 From: hyokeun Date: Tue, 6 Sep 2016 14:09:22 +0900 Subject: Imported Upstream version 2.7.0 --- hw/core/ptimer.c | 83 +++++++++++++++++++++++++++++++++++--------------------- 1 file changed, 52 insertions(+), 31 deletions(-) (limited to 'hw/core/ptimer.c') diff --git a/hw/core/ptimer.c b/hw/core/ptimer.c index 153c83513..30829ee97 100644 --- a/hw/core/ptimer.c +++ b/hw/core/ptimer.c @@ -35,6 +35,9 @@ static void ptimer_trigger(ptimer_state *s) static void ptimer_reload(ptimer_state *s) { + uint32_t period_frac = s->period_frac; + uint64_t period = s->period; + if (s->delta == 0) { ptimer_trigger(s); s->delta = s->limit; @@ -45,10 +48,24 @@ static void ptimer_reload(ptimer_state *s) return; } + /* + * Artificially limit timeout rate to something + * achievable under QEMU. Otherwise, QEMU spends all + * its time generating timer interrupts, and there + * is no forward progress. + * About ten microseconds is the fastest that really works + * on the current generation of host machines. + */ + + if (s->enabled == 1 && (s->delta * period < 10000) && !use_icount) { + period = 10000 / s->delta; + period_frac = 0; + } + s->last_event = s->next_event; - s->next_event = s->last_event + s->delta * s->period; - if (s->period_frac) { - s->next_event += ((int64_t)s->period_frac * s->delta) >> 32; + s->next_event = s->last_event + s->delta * period; + if (period_frac) { + s->next_event += ((int64_t)period_frac * s->delta) >> 32; } timer_mod(s->timer, s->next_event); } @@ -67,14 +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 (expired) { /* Prevent timer underflowing if it should already have triggered. */ counter = 0; @@ -83,6 +102,13 @@ uint64_t ptimer_get_count(ptimer_state *s) uint64_t div; int clz1, clz2; int shift; + uint32_t period_frac = s->period_frac; + uint64_t period = s->period; + + if (!oneshot && (s->delta * period < 10000) && !use_icount) { + period = 10000 / s->delta; + period_frac = 0; + } /* We need to divide time by period, where time is stored in rem (64-bit integer) and period is stored in period/period_frac @@ -94,8 +120,8 @@ uint64_t ptimer_get_count(ptimer_state *s) backwards. */ - rem = s->next_event - now; - div = s->period; + rem = next - now; + div = period; clz1 = clz64(rem); clz2 = clz64(div); @@ -104,13 +130,13 @@ uint64_t ptimer_get_count(ptimer_state *s) rem <<= shift; div <<= shift; if (shift >= 32) { - div |= ((uint64_t)s->period_frac << (shift - 32)); + div |= ((uint64_t)period_frac << (shift - 32)); } else { if (shift != 0) - div |= (s->period_frac >> (32 - shift)); + div |= (period_frac >> (32 - shift)); /* Look at remaining bits of period_frac and round div up if necessary. */ - if ((uint32_t)(s->period_frac << shift)) + if ((uint32_t)(period_frac << shift)) div += 1; } counter = rem / div; @@ -132,16 +158,17 @@ void ptimer_set_count(ptimer_state *s, uint64_t count) void ptimer_run(ptimer_state *s, int oneshot) { - if (s->enabled) { - return; - } - if (s->period == 0) { + bool was_disabled = !s->enabled; + + if (was_disabled && s->period == 0) { fprintf(stderr, "Timer with period zero, disabling\n"); return; } s->enabled = oneshot ? 2 : 1; - s->next_event = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); - ptimer_reload(s); + if (was_disabled) { + s->next_event = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); + ptimer_reload(s); + } } /* Pause a timer. Note that this may cause it to "lose" time, even if it @@ -159,6 +186,7 @@ void ptimer_stop(ptimer_state *s) /* Set counter increment interval in nanoseconds. */ void ptimer_set_period(ptimer_state *s, int64_t period) { + s->delta = ptimer_get_count(s); s->period = period; s->period_frac = 0; if (s->enabled) { @@ -170,6 +198,7 @@ void ptimer_set_period(ptimer_state *s, int64_t period) /* Set counter frequency in Hz. */ void ptimer_set_freq(ptimer_state *s, uint32_t freq) { + s->delta = ptimer_get_count(s); s->period = 1000000000ll / freq; s->period_frac = (1000000000ll << 32) / freq; if (s->enabled) { @@ -182,19 +211,6 @@ void ptimer_set_freq(ptimer_state *s, uint32_t freq) count = limit. */ void ptimer_set_limit(ptimer_state *s, uint64_t limit, int reload) { - /* - * Artificially limit timeout rate to something - * achievable under QEMU. Otherwise, QEMU spends all - * its time generating timer interrupts, and there - * is no forward progress. - * About ten microseconds is the fastest that really works - * on the current generation of host machines. - */ - - if (!use_icount && limit * s->period < 10000 && s->period) { - limit = 10000 / s->period; - } - s->limit = limit; if (reload) s->delta = limit; @@ -204,6 +220,11 @@ void ptimer_set_limit(ptimer_state *s, uint64_t limit, int reload) } } +uint64_t ptimer_get_limit(ptimer_state *s) +{ + return s->limit; +} + const VMStateDescription vmstate_ptimer = { .name = "ptimer", .version_id = 1, -- cgit v1.2.3