aboutsummaryrefslogtreecommitdiff
path: root/hw/mips/cputimer.c
diff options
context:
space:
mode:
authorLaurent Vivier <lvivier@redhat.com>2015-08-25 16:16:21 +0200
committerLaurent Vivier <lvivier@redhat.com>2015-09-25 14:54:04 +0200
commit683dca6bd5057a87d9376475b0c7e30d56d8e532 (patch)
treee9a0ca88dcaf7bd08c4044b1ad0ff9c21478d57f /hw/mips/cputimer.c
parentc6acbe861f1ed4203f4864baf756686064ba561f (diff)
mips: remove muldiv64()
Originally, timers were ticks based, and it made sense to add ticks to current time to know when to trigger an alarm. But since commit: 7447545 change all other clock references to use nanosecond resolution accessors All timers use nanoseconds and we need to convert ticks to nanoseconds, by doing something like: y = muldiv64(x, get_ticks_per_sec(), TIMER_FREQ) where x is the number of device ticks and y the number of system ticks. y is used as nanoseconds in timer functions, it works because 1 tick is 1 nanosecond. (get_ticks_per_sec() is 10^9) But as MIPS timer frequency is 100 MHz, we can also do: y = x * 10; /* 100 MHz period is 10 ns */ Signed-off-by: Laurent Vivier <lvivier@redhat.com> Reviewed-by: Leon Alrae <leon.alrae@imgtec.com>
Diffstat (limited to 'hw/mips/cputimer.c')
-rw-r--r--hw/mips/cputimer.c19
1 files changed, 8 insertions, 11 deletions
diff --git a/hw/mips/cputimer.c b/hw/mips/cputimer.c
index ba9264b415..f046588ada 100644
--- a/hw/mips/cputimer.c
+++ b/hw/mips/cputimer.c
@@ -25,7 +25,7 @@
#include "qemu/timer.h"
#include "sysemu/kvm.h"
-#define TIMER_FREQ 100 * 1000 * 1000
+#define TIMER_PERIOD 10 /* 10 ns period for 100 Mhz frequency */
/* XXX: do not use a global */
uint32_t cpu_mips_get_random (CPUMIPSState *env)
@@ -57,9 +57,8 @@ static void cpu_mips_timer_update(CPUMIPSState *env)
uint32_t wait;
now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
- wait = env->CP0_Compare - env->CP0_Count -
- (uint32_t)muldiv64(now, TIMER_FREQ, get_ticks_per_sec());
- next = now + muldiv64(wait, get_ticks_per_sec(), TIMER_FREQ);
+ wait = env->CP0_Compare - env->CP0_Count - (uint32_t)(now / TIMER_PERIOD);
+ next = now + (uint64_t)wait * TIMER_PERIOD;
timer_mod(env->timer, next);
}
@@ -87,8 +86,7 @@ uint32_t cpu_mips_get_count (CPUMIPSState *env)
cpu_mips_timer_expire(env);
}
- return env->CP0_Count +
- (uint32_t)muldiv64(now, TIMER_FREQ, get_ticks_per_sec());
+ return env->CP0_Count + (uint32_t)(now / TIMER_PERIOD);
}
}
@@ -103,9 +101,8 @@ void cpu_mips_store_count (CPUMIPSState *env, uint32_t count)
env->CP0_Count = count;
else {
/* Store new count register */
- env->CP0_Count =
- count - (uint32_t)muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL),
- TIMER_FREQ, get_ticks_per_sec());
+ env->CP0_Count = count -
+ (uint32_t)(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) / TIMER_PERIOD);
/* Update timer timer */
cpu_mips_timer_update(env);
}
@@ -129,8 +126,8 @@ void cpu_mips_start_count(CPUMIPSState *env)
void cpu_mips_stop_count(CPUMIPSState *env)
{
/* Store the current value */
- env->CP0_Count += (uint32_t)muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL),
- TIMER_FREQ, get_ticks_per_sec());
+ env->CP0_Count += (uint32_t)(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) /
+ TIMER_PERIOD);
}
static void mips_timer_cb (void *opaque)