mirror of https://gitee.com/openkylin/qemu.git
231 lines
6.0 KiB
C
231 lines
6.0 KiB
C
/*
|
|
* General purpose implementation of a simple periodic countdown timer.
|
|
*
|
|
* Copyright (c) 2007 CodeSourcery.
|
|
*
|
|
* This code is licensed under the GNU LGPL.
|
|
*/
|
|
#include "hw/hw.h"
|
|
#include "qemu/timer.h"
|
|
#include "hw/ptimer.h"
|
|
#include "qemu/host-utils.h"
|
|
|
|
struct ptimer_state
|
|
{
|
|
uint8_t enabled; /* 0 = disabled, 1 = periodic, 2 = oneshot. */
|
|
uint64_t limit;
|
|
uint64_t delta;
|
|
uint32_t period_frac;
|
|
int64_t period;
|
|
int64_t last_event;
|
|
int64_t next_event;
|
|
QEMUBH *bh;
|
|
QEMUTimer *timer;
|
|
};
|
|
|
|
/* Use a bottom-half routine to avoid reentrancy issues. */
|
|
static void ptimer_trigger(ptimer_state *s)
|
|
{
|
|
if (s->bh) {
|
|
qemu_bh_schedule(s->bh);
|
|
}
|
|
}
|
|
|
|
static void ptimer_reload(ptimer_state *s)
|
|
{
|
|
if (s->delta == 0) {
|
|
ptimer_trigger(s);
|
|
s->delta = s->limit;
|
|
}
|
|
if (s->delta == 0 || s->period == 0) {
|
|
fprintf(stderr, "Timer with period zero, disabling\n");
|
|
s->enabled = 0;
|
|
return;
|
|
}
|
|
|
|
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;
|
|
}
|
|
timer_mod(s->timer, s->next_event);
|
|
}
|
|
|
|
static void ptimer_tick(void *opaque)
|
|
{
|
|
ptimer_state *s = (ptimer_state *)opaque;
|
|
ptimer_trigger(s);
|
|
s->delta = 0;
|
|
if (s->enabled == 2) {
|
|
s->enabled = 0;
|
|
} else {
|
|
ptimer_reload(s);
|
|
}
|
|
}
|
|
|
|
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);
|
|
/* Figure out the current counter value. */
|
|
if (now - s->next_event > 0
|
|
|| s->period == 0) {
|
|
/* Prevent timer underflowing if it should already have
|
|
triggered. */
|
|
counter = 0;
|
|
} else {
|
|
uint64_t rem;
|
|
uint64_t div;
|
|
int clz1, clz2;
|
|
int shift;
|
|
|
|
/* We need to divide time by period, where time is stored in
|
|
rem (64-bit integer) and period is stored in period/period_frac
|
|
(64.32 fixed point).
|
|
|
|
Doing full precision division is hard, so scale values and
|
|
do a 64-bit division. The result should be rounded down,
|
|
so that the rounding error never causes the timer to go
|
|
backwards.
|
|
*/
|
|
|
|
rem = s->next_event - now;
|
|
div = s->period;
|
|
|
|
clz1 = clz64(rem);
|
|
clz2 = clz64(div);
|
|
shift = clz1 < clz2 ? clz1 : clz2;
|
|
|
|
rem <<= shift;
|
|
div <<= shift;
|
|
if (shift >= 32) {
|
|
div |= ((uint64_t)s->period_frac << (shift - 32));
|
|
} else {
|
|
if (shift != 0)
|
|
div |= (s->period_frac >> (32 - shift));
|
|
/* Look at remaining bits of period_frac and round div up if
|
|
necessary. */
|
|
if ((uint32_t)(s->period_frac << shift))
|
|
div += 1;
|
|
}
|
|
counter = rem / div;
|
|
}
|
|
} else {
|
|
counter = s->delta;
|
|
}
|
|
return counter;
|
|
}
|
|
|
|
void ptimer_set_count(ptimer_state *s, uint64_t count)
|
|
{
|
|
s->delta = count;
|
|
if (s->enabled) {
|
|
s->next_event = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
|
|
ptimer_reload(s);
|
|
}
|
|
}
|
|
|
|
void ptimer_run(ptimer_state *s, int oneshot)
|
|
{
|
|
if (s->enabled) {
|
|
return;
|
|
}
|
|
if (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);
|
|
}
|
|
|
|
/* Pause a timer. Note that this may cause it to "lose" time, even if it
|
|
is immediately restarted. */
|
|
void ptimer_stop(ptimer_state *s)
|
|
{
|
|
if (!s->enabled)
|
|
return;
|
|
|
|
s->delta = ptimer_get_count(s);
|
|
timer_del(s->timer);
|
|
s->enabled = 0;
|
|
}
|
|
|
|
/* Set counter increment interval in nanoseconds. */
|
|
void ptimer_set_period(ptimer_state *s, int64_t period)
|
|
{
|
|
s->period = period;
|
|
s->period_frac = 0;
|
|
if (s->enabled) {
|
|
s->next_event = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
|
|
ptimer_reload(s);
|
|
}
|
|
}
|
|
|
|
/* Set counter frequency in Hz. */
|
|
void ptimer_set_freq(ptimer_state *s, uint32_t freq)
|
|
{
|
|
s->period = 1000000000ll / freq;
|
|
s->period_frac = (1000000000ll << 32) / freq;
|
|
if (s->enabled) {
|
|
s->next_event = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
|
|
ptimer_reload(s);
|
|
}
|
|
}
|
|
|
|
/* Set the initial countdown value. If reload is nonzero then also set
|
|
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 (limit * s->period < 10000 && s->period) {
|
|
limit = 10000 / s->period;
|
|
}
|
|
|
|
s->limit = limit;
|
|
if (reload)
|
|
s->delta = limit;
|
|
if (s->enabled && reload) {
|
|
s->next_event = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
|
|
ptimer_reload(s);
|
|
}
|
|
}
|
|
|
|
const VMStateDescription vmstate_ptimer = {
|
|
.name = "ptimer",
|
|
.version_id = 1,
|
|
.minimum_version_id = 1,
|
|
.fields = (VMStateField[]) {
|
|
VMSTATE_UINT8(enabled, ptimer_state),
|
|
VMSTATE_UINT64(limit, ptimer_state),
|
|
VMSTATE_UINT64(delta, ptimer_state),
|
|
VMSTATE_UINT32(period_frac, ptimer_state),
|
|
VMSTATE_INT64(period, ptimer_state),
|
|
VMSTATE_INT64(last_event, ptimer_state),
|
|
VMSTATE_INT64(next_event, ptimer_state),
|
|
VMSTATE_TIMER(timer, ptimer_state),
|
|
VMSTATE_END_OF_LIST()
|
|
}
|
|
};
|
|
|
|
ptimer_state *ptimer_init(QEMUBH *bh)
|
|
{
|
|
ptimer_state *s;
|
|
|
|
s = (ptimer_state *)g_malloc0(sizeof(ptimer_state));
|
|
s->bh = bh;
|
|
s->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, ptimer_tick, s);
|
|
return s;
|
|
}
|