diff options
author | Laurent Vivier <lvivier@redhat.com> | 2015-08-25 16:16:21 +0200 |
---|---|---|
committer | Laurent Vivier <lvivier@redhat.com> | 2015-09-25 14:54:04 +0200 |
commit | 683dca6bd5057a87d9376475b0c7e30d56d8e532 (patch) | |
tree | e9a0ca88dcaf7bd08c4044b1ad0ff9c21478d57f /hw | |
parent | c6acbe861f1ed4203f4864baf756686064ba561f (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')
-rw-r--r-- | hw/mips/cputimer.c | 19 |
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) |