Value matching allows Linux to boot with CONFIG_NO_HZ_IDLE=y on the
palmetto-bmc machine. Two match registers are provided for each timer.
Signed-off-by: Andrew Jeffery <and...@aj.id.au>
---
The change pulls out ptimer in favour of the regular timer infrastructure. As a
consequence it implements the conversions between ticks and time which feels a
little tedious. Any comments there would be appreciated.
hw/timer/aspeed_timer.c | 135 ++++++++++++++++++++++++++++++----------
include/hw/timer/aspeed_timer.h | 6 +-
2 files changed, 105 insertions(+), 36 deletions(-)
diff --git a/hw/timer/aspeed_timer.c b/hw/timer/aspeed_timer.c
index 4b94808821b4..905de0f788b2 100644
--- a/hw/timer/aspeed_timer.c
+++ b/hw/timer/aspeed_timer.c
@@ -9,13 +9,12 @@
* the COPYING file in the top-level directory.
*/
+#include <math.h>
#include "qemu/osdep.h"
-#include "hw/ptimer.h"
#include "hw/sysbus.h"
#include "hw/timer/aspeed_timer.h"
#include "qemu-common.h"
#include "qemu/bitops.h"
-#include "qemu/main-loop.h"
#include "qemu/timer.h"
#include "qemu/log.h"
#include "trace.h"
@@ -77,21 +76,99 @@ static inline bool timer_can_pulse(AspeedTimer *t)
return t->id >= TIMER_FIRST_CAP_PULSE;
}
+static inline bool timer_external_clock(AspeedTimer *t)
+{
+ return timer_ctrl_status(t, op_external_clock);
+}
+
+static double clock_rates[] = { TIMER_CLOCK_APB_HZ, TIMER_CLOCK_EXT_HZ };
+
+static inline double calculate_rate(struct AspeedTimer *t)
+{
+ return clock_rates[timer_external_clock(t)];
+}
+
+static inline double calculate_period(struct AspeedTimer *t)
+{
+ return NANOSECONDS_PER_SECOND / calculate_rate(t);
+}
+
+static inline uint32_t calculate_ticks(struct AspeedTimer *t, uint64_t now_ns)
+{
+ uint64_t delta_ns = now_ns - MIN(now_ns, t->start);
+ uint32_t ticks = (uint32_t) floor(delta_ns / calculate_period(t));
+
+ return t->reload - MIN(t->reload, ticks);
+}
+
+static inline uint64_t calculate_time(struct AspeedTimer *t, uint32_t ticks)
+{
+ uint64_t delta_ns;
+
+ ticks = MIN(t->reload, ticks);
+ delta_ns = (uint64_t) floor((t->reload - ticks) * calculate_period(t));
+
+ return t->start + delta_ns;
+}
+
+static uint64_t calculate_next(struct AspeedTimer *t)
+{
+ uint64_t now;
+ uint64_t next;
+ int i;
+ /* We don't know the relationship between the values in the match
+ * registers, so sort using MAX/MIN/zero. We sort in that order as the
+ * timer counts down to zero. */
+ uint64_t seq[] = {
+ MAX(t->match[0], t->match[1]),
+ MIN(t->match[0], t->match[1]),
+ 0,
+ };
+
+ now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+ for (i = 0; i < ARRAY_SIZE(seq); i++) {
+ next = calculate_time(t, seq[i]);
+ if (now < next) {
+ return next;
+ }
+ }
+
+ {
+ uint64_t reload_ns;
+
+ reload_ns = (uint64_t) floor(t->reload * calculate_period(t));
+ t->start = now - ((now - t->start) % reload_ns);
+ }
+
+ return calculate_next(t);
+}
+
static void aspeed_timer_expire(void *opaque)
{
AspeedTimer *t = opaque;
+ bool interrupt = false;
+ uint32_t ticks;
- /* Only support interrupts on match values of zero for the moment - this is
- * sufficient to boot an aspeed_defconfig Linux kernel.
- *
- * TODO: matching on arbitrary values (see e.g. hw/timer/a9gtimer.c)
- */
- bool match = !(t->match[0] && t->match[1]);
- bool interrupt = timer_overflow_interrupt(t) || match;
- if (timer_enabled(t) && interrupt) {
+ if (!timer_enabled(t)) {
+ return;
+ }
+
+ ticks = calculate_ticks(t, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
+
+ if (!ticks) {
+ interrupt = timer_overflow_interrupt(t) || !t->match[0] ||
!t->match[1];
+ } else if (ticks <= MIN(t->match[0], t->match[1])) {
+ interrupt = true;
+ } else if (ticks <= MAX(t->match[0], t->match[1])) {
+ interrupt = true;
+ }
+
+ if (interrupt) {
t->level = !t->level;
qemu_set_irq(t->irq, t->level);
}
+
+ timer_mod(&t->timer, calculate_next(t));
}
static uint64_t aspeed_timer_get_value(AspeedTimer *t, int reg)
@@ -100,7 +177,7 @@ static uint64_t aspeed_timer_get_value(AspeedTimer *t, int
reg)
switch (reg) {
case TIMER_REG_STATUS:
- value = ptimer_get_count(t->timer);
+ value = calculate_ticks(t, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
break;
case TIMER_REG_RELOAD:
value = t->reload;
@@ -160,24 +237,21 @@ static void aspeed_timer_set_value(AspeedTimerCtrlState
*s, int timer, int reg,
switch (reg) {
case TIMER_REG_STATUS:
if (timer_enabled(t)) {
- ptimer_set_count(t->timer, value);
+ uint64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+ int64_t delta = (int64_t) value - (int64_t) calculate_ticks(t,
now);
+
+ t->start += delta * calculate_period(t);
+ timer_mod(&t->timer, calculate_next(t));
}
break;
case TIMER_REG_RELOAD:
t->reload = value;
- ptimer_set_limit(t->timer, value, 1);
break;
case TIMER_REG_MATCH_FIRST:
case TIMER_REG_MATCH_SECOND:
- if (value) {
- /* Non-zero match values are unsupported. As such an interrupt will
- * always be triggered when the timer reaches zero even if the
- * overflow interrupt control bit is clear.
- */
- qemu_log_mask(LOG_UNIMP, "%s: Match value unsupported by device: "
- "0x%" PRIx32 "\n", __func__, value);
- } else {
- t->match[reg - 2] = value;
+ t->match[reg - 2] = value;
+ if (timer_enabled(t)) {
+ timer_mod(&t->timer, calculate_next(t));
}
break;
default:
@@ -196,21 +270,16 @@ static void aspeed_timer_ctrl_enable(AspeedTimer *t, bool
enable)
{
trace_aspeed_timer_ctrl_enable(t->id, enable);
if (enable) {
- ptimer_run(t->timer, 0);
+ t->start = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+ timer_mod(&t->timer, calculate_next(t));
} else {
- ptimer_stop(t->timer);
- ptimer_set_limit(t->timer, t->reload, 1);
+ timer_del(&t->timer);
}
}
static void aspeed_timer_ctrl_external_clock(AspeedTimer *t, bool enable)
{
trace_aspeed_timer_ctrl_external_clock(t->id, enable);
- if (enable) {
- ptimer_set_freq(t->timer, TIMER_CLOCK_EXT_HZ);
- } else {
- ptimer_set_freq(t->timer, TIMER_CLOCK_APB_HZ);
- }
}
static void aspeed_timer_ctrl_overflow_interrupt(AspeedTimer *t, bool enable)
@@ -351,12 +420,10 @@ static const MemoryRegionOps aspeed_timer_ops = {
static void aspeed_init_one_timer(AspeedTimerCtrlState *s, uint8_t id)
{
- QEMUBH *bh;
AspeedTimer *t = &s->timers[id];
t->id = id;
- bh = qemu_bh_new(aspeed_timer_expire, t);
- t->timer = ptimer_init(bh);
+ timer_init_ns(&t->timer, QEMU_CLOCK_VIRTUAL, aspeed_timer_expire, t);
}
static void aspeed_timer_realize(DeviceState *dev, Error **errp)
@@ -404,7 +471,7 @@ static const VMStateDescription vmstate_aspeed_timer = {
.fields = (VMStateField[]) {
VMSTATE_UINT8(id, AspeedTimer),
VMSTATE_INT32(level, AspeedTimer),
- VMSTATE_PTIMER(timer, AspeedTimer),
+ VMSTATE_TIMER(timer, AspeedTimer),
VMSTATE_UINT32(reload, AspeedTimer),
VMSTATE_UINT32_ARRAY(match, AspeedTimer, 2),
VMSTATE_END_OF_LIST()
diff --git a/include/hw/timer/aspeed_timer.h b/include/hw/timer/aspeed_timer.h
index 44dc2f89d5c6..970fea83143c 100644
--- a/include/hw/timer/aspeed_timer.h
+++ b/include/hw/timer/aspeed_timer.h
@@ -22,7 +22,8 @@
#ifndef ASPEED_TIMER_H
#define ASPEED_TIMER_H
-#include "hw/ptimer.h"
+#include "qemu/typedefs.h"
+#include "qemu/timer.h"
#define ASPEED_TIMER(obj) \
OBJECT_CHECK(AspeedTimerCtrlState, (obj), TYPE_ASPEED_TIMER);
@@ -33,15 +34,16 @@ typedef struct AspeedTimer {
qemu_irq irq;
uint8_t id;
+ QEMUTimer timer;
/**
* Track the line level as the ASPEED timers implement edge triggered
* interrupts, signalling with both the rising and falling edge.
*/
int32_t level;
- ptimer_state *timer;
uint32_t reload;
uint32_t match[2];
+ uint64_t start;
} AspeedTimer;
typedef struct AspeedTimerCtrlState {
--
2.7.4
