diff options
| -rw-r--r-- | hw/ppc/ppc.c | 31 |
1 files changed, 19 insertions, 12 deletions
diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c index 423a3a117a..13eb45f4b7 100644 --- a/hw/ppc/ppc.c +++ b/hw/ppc/ppc.c @@ -482,14 +482,26 @@ void ppce500_set_mpic_proxy(bool enabled) /*****************************************************************************/ /* PowerPC time base and decrementer emulation */ +/* + * Conversion between QEMU_CLOCK_VIRTUAL ns and timebase (TB) ticks: + * TB ticks are arrived at by multiplying tb_freq then dividing by + * ns per second, and rounding down. TB ticks drive all clocks and + * timers in the target machine. + * + * Converting TB intervals to ns for the purpose of setting a + * QEMU_CLOCK_VIRTUAL timer should go the other way, but rounding + * up. Rounding down could cause the timer to fire before the TB + * value has been reached. + */ static uint64_t ns_to_tb(uint32_t freq, int64_t clock) { return muldiv64(clock, freq, NANOSECONDS_PER_SECOND); } -static int64_t tb_to_ns(uint32_t freq, uint64_t tb) +/* virtual clock in TB ticks, not adjusted by TB offset */ +static int64_t tb_to_ns_round_up(uint32_t freq, uint64_t tb) { - return muldiv64(tb, NANOSECONDS_PER_SECOND, freq); + return muldiv64_round_up(tb, NANOSECONDS_PER_SECOND, freq); } uint64_t cpu_ppc_get_tb(ppc_tb_t *tb_env, uint64_t vmclk, int64_t tb_offset) @@ -847,7 +859,7 @@ static void __cpu_ppc_store_decr(PowerPCCPU *cpu, uint64_t *nextp, /* Calculate the next timer event */ now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); - next = now + tb_to_ns(tb_env->decr_freq, value); + next = now + tb_to_ns_round_up(tb_env->decr_freq, value); *nextp = next; /* Adjust timer */ @@ -1139,9 +1151,7 @@ static void cpu_4xx_fit_cb (void *opaque) /* Cannot occur, but makes gcc happy */ return; } - next = now + tb_to_ns(tb_env->tb_freq, next); - if (next == now) - next++; + next = now + tb_to_ns_round_up(tb_env->tb_freq, next); timer_mod(ppc40x_timer->fit_timer, next); env->spr[SPR_40x_TSR] |= 1 << 26; if ((env->spr[SPR_40x_TCR] >> 23) & 0x1) { @@ -1167,11 +1177,10 @@ static void start_stop_pit (CPUPPCState *env, ppc_tb_t *tb_env, int is_excp) } else { trace_ppc4xx_pit_start(ppc40x_timer->pit_reload); now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); - next = now + tb_to_ns(tb_env->decr_freq, ppc40x_timer->pit_reload); + next = now + tb_to_ns_round_up(tb_env->decr_freq, + ppc40x_timer->pit_reload); if (is_excp) next += tb_env->decr_next - now; - if (next == now) - next++; timer_mod(tb_env->decr_timer, next); tb_env->decr_next = next; } @@ -1226,9 +1235,7 @@ static void cpu_4xx_wdt_cb (void *opaque) /* Cannot occur, but makes gcc happy */ return; } - next = now + tb_to_ns(tb_env->decr_freq, next); - if (next == now) - next++; + next = now + tb_to_ns_round_up(tb_env->decr_freq, next); trace_ppc4xx_wdt(env->spr[SPR_40x_TCR], env->spr[SPR_40x_TSR]); switch ((env->spr[SPR_40x_TSR] >> 30) & 0x3) { case 0x0: |