Commit 683dca6b authored by Laurent Vivier's avatar Laurent Vivier
Browse files

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:

74475455 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: default avatarLaurent Vivier <lvivier@redhat.com>
Reviewed-by: default avatarLeon Alrae <leon.alrae@imgtec.com>
parent c6acbe86

hw/mips/cputimer.c

+8 −11
Original line number Diff line number Diff line
@@ -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)