diff options
author | Laurent Vivier <lvivier@redhat.com> | 2015-08-25 17:17:15 +0200 |
---|---|---|
committer | Laurent Vivier <lvivier@redhat.com> | 2015-09-25 14:54:22 +0200 |
commit | ccaf1749239aa33c5a5b755972232ffe1c0cf946 (patch) | |
tree | c52fc1d092f37976f1503a64d3613c1b48ac8a3e /hw | |
parent | 683dca6bd5057a87d9376475b0c7e30d56d8e532 (diff) |
openrisc: 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 openrisc timer frequency is 20 MHz, we can also do:
y = x * 50; /* 20 MHz period is 50 ns */
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Diffstat (limited to 'hw')
-rw-r--r-- | hw/openrisc/cputimer.c | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/hw/openrisc/cputimer.c b/hw/openrisc/cputimer.c index 9c54945107..560cb914c5 100644 --- a/hw/openrisc/cputimer.c +++ b/hw/openrisc/cputimer.c @@ -22,7 +22,7 @@ #include "hw/hw.h" #include "qemu/timer.h" -#define TIMER_FREQ (20 * 1000 * 1000) /* 20MHz */ +#define TIMER_PERIOD 50 /* 50 ns period for 20 MHz timer */ /* The time when TTCR changes */ static uint64_t last_clk; @@ -36,8 +36,7 @@ void cpu_openrisc_count_update(OpenRISCCPU *cpu) return; } now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); - cpu->env.ttcr += (uint32_t)muldiv64(now - last_clk, TIMER_FREQ, - get_ticks_per_sec()); + cpu->env.ttcr += (uint32_t)((now - last_clk) / TIMER_PERIOD); last_clk = now; } @@ -59,7 +58,7 @@ void cpu_openrisc_timer_update(OpenRISCCPU *cpu) } else { wait = (cpu->env.ttmr & TTMR_TP) - (cpu->env.ttcr & TTMR_TP); } - next = now + muldiv64(wait, get_ticks_per_sec(), TIMER_FREQ); + next = now + (uint64_t)wait * TIMER_PERIOD; timer_mod(cpu->env.timer, next); } |