Commit 423f0742 authored by pbrook's avatar pbrook
Browse files

Add periodic timer implementation.


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@2846 c046a42c-6fe2-441c-8c8c-71466251a162
parent 0ff596d0
......@@ -22,114 +22,24 @@
#define TIMER_CTRL_ENABLE (1 << 7)
typedef struct {
int64_t next_time;
int64_t expires;
int64_t loaded;
QEMUTimer *timer;
ptimer_state *timer;
uint32_t control;
uint32_t count;
uint32_t limit;
int raw_freq;
int freq;
int int_level;
qemu_irq irq;
} arm_timer_state;
/* Calculate the new expiry time of the given timer. */
static void arm_timer_reload(arm_timer_state *s)
{
int64_t delay;
s->loaded = s->expires;
delay = muldiv64(s->count, ticks_per_sec, s->freq);
if (delay == 0)
delay = 1;
s->expires += delay;
}
/* Check all active timers, and schedule the next timer interrupt. */
static void arm_timer_update(arm_timer_state *s, int64_t now)
static void arm_timer_update(arm_timer_state *s)
{
int64_t next;
/* Ignore disabled timers. */
if ((s->control & TIMER_CTRL_ENABLE) == 0)
return;
/* Ignore expired one-shot timers. */
if (s->count == 0 && (s->control & TIMER_CTRL_ONESHOT))
return;
if (s->expires - now <= 0) {
/* Timer has expired. */
s->int_level = 1;
if (s->control & TIMER_CTRL_ONESHOT) {
/* One-shot. */
s->count = 0;
} else {
if ((s->control & TIMER_CTRL_PERIODIC) == 0) {
/* Free running. */
if (s->control & TIMER_CTRL_32BIT)
s->count = 0xffffffff;
else
s->count = 0xffff;
} else {
/* Periodic. */
s->count = s->limit;
}
}
}
while (s->expires - now <= 0) {
arm_timer_reload(s);
}
/* Update interrupts. */
if (s->int_level && (s->control & TIMER_CTRL_IE)) {
qemu_irq_raise(s->irq);
} else {
qemu_irq_lower(s->irq);
}
next = now;
if (next - s->expires < 0)
next = s->expires;
/* Schedule the next timer interrupt. */
if (next == now) {
qemu_del_timer(s->timer);
s->next_time = 0;
} else if (next != s->next_time) {
qemu_mod_timer(s->timer, next);
s->next_time = next;
}
}
/* Return the current value of the timer. */
static uint32_t arm_timer_getcount(arm_timer_state *s, int64_t now)
{
int64_t left;
int64_t period;
if (s->count == 0)
return 0;
if ((s->control & TIMER_CTRL_ENABLE) == 0)
return s->count;
left = s->expires - now;
period = s->expires - s->loaded;
/* If the timer should have expired then return 0. This can happen
when the host timer signal doesnt occur immediately. It's better to
have a timer appear to sit at zero for a while than have it wrap
around before the guest interrupt is raised. */
/* ??? Could we trigger the interrupt here? */
if (left < 0)
return 0;
/* We need to calculate count * elapsed / period without overfowing.
Scale both elapsed and period so they fit in a 32-bit int. */
while (period != (int32_t)period) {
period >>= 1;
left >>= 1;
}
return ((uint64_t)s->count * (uint64_t)(int32_t)left)
/ (int32_t)period;
}
uint32_t arm_timer_read(void *opaque, target_phys_addr_t offset)
......@@ -141,7 +51,7 @@ uint32_t arm_timer_read(void *opaque, target_phys_addr_t offset)
case 6: /* TimerBGLoad */
return s->limit;
case 1: /* TimerValue */
return arm_timer_getcount(s, qemu_get_clock(vm_clock));
return ptimer_get_count(s->timer);
case 2: /* TimerControl */
return s->control;
case 4: /* TimerRIS */
......@@ -151,24 +61,40 @@ uint32_t arm_timer_read(void *opaque, target_phys_addr_t offset)
return 0;
return s->int_level;
default:
cpu_abort (cpu_single_env, "arm_timer_read: Bad offset %x\n", offset);
cpu_abort (cpu_single_env, "arm_timer_read: Bad offset %x\n",
(int)offset);
return 0;
}
}
/* Reset the timer limit after settings have changed. */
static void arm_timer_recalibrate(arm_timer_state *s, int reload)
{
uint32_t limit;
if ((s->control & TIMER_CTRL_PERIODIC) == 0) {
/* Free running. */
if (s->control & TIMER_CTRL_32BIT)
limit = 0xffffffff;
else
limit = 0xffff;
} else {
/* Periodic. */
limit = s->limit;
}
ptimer_set_limit(s->timer, limit, reload);
}
static void arm_timer_write(void *opaque, target_phys_addr_t offset,
uint32_t value)
{
arm_timer_state *s = (arm_timer_state *)opaque;
int64_t now;
int freq;
now = qemu_get_clock(vm_clock);
switch (offset >> 2) {
case 0: /* TimerLoad */
s->limit = value;
s->count = value;
s->expires = now;
arm_timer_reload(s);
arm_timer_recalibrate(s, 1);
break;
case 1: /* TimerValue */
/* ??? Linux seems to want to write to this readonly register.
......@@ -179,19 +105,20 @@ static void arm_timer_write(void *opaque, target_phys_addr_t offset,
/* Pause the timer if it is running. This may cause some
inaccuracy dure to rounding, but avoids a whole lot of other
messyness. */
s->count = arm_timer_getcount(s, now);
ptimer_stop(s->timer);
}
s->control = value;
s->freq = s->raw_freq;
freq = s->freq;
/* ??? Need to recalculate expiry time after changing divisor. */
switch ((value >> 2) & 3) {
case 1: s->freq >>= 4; break;
case 2: s->freq >>= 8; break;
case 1: freq >>= 4; break;
case 2: freq >>= 8; break;
}
arm_timer_recalibrate(s, 0);
ptimer_set_freq(s->timer, freq);
if (s->control & TIMER_CTRL_ENABLE) {
/* Restart the timer if still enabled. */
s->expires = now;
arm_timer_reload(s);
ptimer_run(s->timer, (s->control & TIMER_CTRL_ONESHOT) != 0);
}
break;
case 3: /* TimerIntClr */
......@@ -199,32 +126,34 @@ static void arm_timer_write(void *opaque, target_phys_addr_t offset,
break;
case 6: /* TimerBGLoad */
s->limit = value;
arm_timer_recalibrate(s, 0);
break;
default:
cpu_abort (cpu_single_env, "arm_timer_write: Bad offset %x\n", offset);
cpu_abort (cpu_single_env, "arm_timer_write: Bad offset %x\n",
(int)offset);
}
arm_timer_update(s, now);
arm_timer_update(s);
}
static void arm_timer_tick(void *opaque)
{
int64_t now;
now = qemu_get_clock(vm_clock);
arm_timer_update((arm_timer_state *)opaque, now);
arm_timer_state *s = (arm_timer_state *)opaque;
s->int_level = 1;
arm_timer_update(s);
}
static void *arm_timer_init(uint32_t freq, qemu_irq irq)
{
arm_timer_state *s;
QEMUBH *bh;
s = (arm_timer_state *)qemu_mallocz(sizeof(arm_timer_state));
s->irq = irq;
s->raw_freq = s->freq = 1000000;
s->freq = freq;
s->control = TIMER_CTRL_IE;
s->count = 0xffffffff;
s->timer = qemu_new_timer(vm_clock, arm_timer_tick, s);
bh = qemu_bh_new(arm_timer_tick, s);
s->timer = ptimer_init(bh);
/* ??? Save/restore. */
return s;
}
......
/*
* General purpose implementation of a simple periodic countdown timer.
*
* Copyright (c) 2007 CodeSourcery.
*
* This code is licenced under the GNU LGPL.
*/
#include "vl.h"
struct ptimer_state
{
int enabled; /* 0 = disabled, 1 = periodic, 2 = oneshot. */
uint32_t limit;
uint32_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;
}
qemu_mod_timer(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);
}
}
uint32_t ptimer_get_count(ptimer_state *s)
{
int64_t now;
uint32_t counter;
if (s->enabled) {
now = qemu_get_clock(vm_clock);
/* 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 {
int64_t rem;
int64_t div;
rem = s->next_event - now;
div = s->period;
counter = rem / div;
}
} else {
counter = s->delta;
}
return counter;
}
void ptimer_set_count(ptimer_state *s, uint32_t count)
{
s->delta = count;
if (s->enabled) {
s->next_event = qemu_get_clock(vm_clock);
ptimer_reload(s);
}
}
void ptimer_run(ptimer_state *s, int oneshot)
{
if (s->period == 0) {
fprintf(stderr, "Timer with period zero, disabling\n");
return;
}
s->enabled = oneshot ? 2 : 1;
s->next_event = qemu_get_clock(vm_clock);
ptimer_reload(s);
}
/* Pause a timer. Note that this may cause it to "loose" time, even if it
is immediately restarted. */
void ptimer_stop(ptimer_state *s)
{
if (!s->enabled)
return;
s->delta = ptimer_get_count(s);
qemu_del_timer(s->timer);
s->enabled = 0;
}
/* Set counter increment interval in nanoseconds. */
void ptimer_set_period(ptimer_state *s, int64_t period)
{
if (s->enabled) {
fprintf(stderr, "FIXME: ptimer_set_period with running timer");
}
s->period = period;
s->period_frac = 0;
}
/* Set counter frequency in Hz. */
void ptimer_set_freq(ptimer_state *s, uint32_t freq)
{
if (s->enabled) {
fprintf(stderr, "FIXME: ptimer_set_freq with running timer");
}
s->period = 1000000000ll / freq;
s->period_frac = (1000000000ll << 32) / freq;
}
/* Set the initial countdown value. If reload is nonzero then also set
count = limit. */
void ptimer_set_limit(ptimer_state *s, uint32_t limit, int reload)
{
if (s->enabled) {
fprintf(stderr, "FIXME: ptimer_set_limit with running timer");
}
s->limit = limit;
if (reload)
s->delta = limit;
}
ptimer_state *ptimer_init(QEMUBH *bh)
{
ptimer_state *s;
s = (ptimer_state *)qemu_mallocz(sizeof(ptimer_state));
s->bh = bh;
s->timer = qemu_new_timer(vm_clock, ptimer_tick, s);
return s;
}
......@@ -6322,7 +6322,6 @@ void main_loop_wait(int timeout)
}
#endif
qemu_aio_poll();
qemu_bh_poll();
if (vm_running) {
qemu_run_timers(&active_timers[QEMU_TIMER_VIRTUAL],
......@@ -6330,10 +6329,15 @@ void main_loop_wait(int timeout)
/* run dma transfers, if any */
DMA_run();
}
/* real time timers */
qemu_run_timers(&active_timers[QEMU_TIMER_REALTIME],
qemu_get_clock(rt_clock));
/* Check bottom-halves last in case any of the earlier events triggered
them. */
qemu_bh_poll();
}
static CPUState *cur_cpu;
......
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