aspeed_timer: Add clock value matching support

Allows Linux to boot with CONFIG_NO_HZ_IDLE=y. Both match registers are
supported for all timers.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>

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 "trace.h"
 
@@ -76,21 +75,120 @@ 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 inline double calculate_period(struct AspeedTimer *t)
+{
+ double rate;
+
+ rate = timer_external_clock(t) ? TIMER_CLOCK_EXT_HZ : TIMER_CLOCK_APB_HZ;
+
+ return 1000000000.0 / rate;
+}
+
+static uint64_t calculate_value(struct AspeedTimer *t, uint64_t now_ns)
+{
+ double ticks;
+
+ ticks = floor((now_ns - t->start) / calculate_period(t));
+ return t->reload - MIN(t->reload, (uint64_t) ticks);
+}
+
+static uint64_t calculate_now_to(struct AspeedTimer *t, uint64_t target)
+{
+ uint64_t now;
+ double ticks;
+
+ now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+ ticks = (t->reload - target) - ((now - t->start) / calculate_period(t));
+ return (uint64_t) ceil(ticks);
+}
+
+static uint64_t ticks_to_ns(struct AspeedTimer *t, uint32_t ticks)
+{
+ double delta_ns;
+
+ ticks = MIN(t->reload, ticks);
+ delta_ns = floor((t->reload - ticks) * calculate_period(t));
+
+ return t->start + (uint64_t) delta_ns;
+}
+
+static uint64_t calculate_next(struct AspeedTimer *t)
+{
+ uint64_t now;
+ uint64_t next;
+ int i;
+ 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 = ticks_to_ns(t, seq[i]);
+ if (now < next) {
+ return next;
+ }
+ }
+ return 0;
+}
+
+static bool is_match(struct AspeedTimer *t, int idx, uint64_t now_ns)
+{
+ return calculate_value(t, now_ns) <= t->match[idx] && !t->match_irq[idx];
+}
+
+static void update_timer(struct AspeedTimer *t)
+{
+ uint64_t next;
+
+ next = calculate_next(t);
+ while (!next) {
+ t->start = ticks_to_ns(t, 0);
+ next = calculate_next(t);
+ }
+
+ timer_mod(&t->timer, next);
+}
+
 static void aspeed_timer_expire(void *opaque)
 {
  AspeedTimer *t = opaque;
+ bool matched;
+ bool interrupt = false;
+ uint64_t now;
 
- /* 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;
+ }
+
+ now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+
+ matched = is_match(t, 0, now);
+ t->match_irq[0] |= matched;
+ interrupt |= matched;
+
+ matched = is_match(t, 1, now);
+ t->match_irq[1] |= matched;
+ interrupt |= matched;
+
+ if (!calculate_value(t, now)) {
+ interrupt |= timer_overflow_interrupt(t);
+ t->match_irq[0] = false;
+ t->match_irq[1] = false;
+ }
+
+ if (interrupt) {
  t->level = !t->level;
  qemu_set_irq(t->irq, t->level);
  }
+
+ update_timer(t);
 }
 
 static uint64_t aspeed_timer_get_value(AspeedTimer *t, int reg)
@@ -99,7 +197,7 @@ 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_value(t, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
  break;
  case TIMER_REG_RELOAD:
  value = t->reload;
@@ -159,24 +257,20 @@ 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);
+ t->start = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+ timer_mod(&t->timer, calculate_now_to(t, value));
  }
  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)) {
+ uint64_t next = calculate_next(t);
+ timer_mod(&t->timer,
+ next ? next : qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
  }
  break;
  default:
@@ -195,21 +289,25 @@ 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);
+ uint64_t next;
+
+ t->start = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+ t->match_irq[0] = false;
+ t->match_irq[1] = false;
+ next = calculate_next(t);
+ if (!next) {
+ next = t->start;
+ }
+
+ timer_mod(&t->timer, next);
  } 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)
@@ -350,12 +448,10 @@ 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)
@@ -403,7 +499,7 @@ 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()

include/hw/timer/aspeed_timer.h

@@ -22,7 +22,7 @@
 #ifndef ASPEED_TIMER_H
 #define ASPEED_TIMER_H
 
-#include "hw/ptimer.h"
+#include "qemu/typedefs.h"
 
 #define ASPEED_TIMER(obj) \
  OBJECT_CHECK(AspeedTimerCtrlState, (obj), TYPE_ASPEED_TIMER);
@@ -31,17 +31,18 @@
 
 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];
+ bool match_irq[2];
+ uint64_t start;
 } AspeedTimer;
 
 typedef struct AspeedTimerCtrlState {