diff options
| -rw-r--r-- | arch/x86/kernel/apic_32.c | 86 | ||||
| -rw-r--r-- | arch/x86/kernel/apic_64.c | 215 |
2 files changed, 301 insertions, 0 deletions
diff --git a/arch/x86/kernel/apic_32.c b/arch/x86/kernel/apic_32.c index 60a901b..05498c3 100644 --- a/arch/x86/kernel/apic_32.c +++ b/arch/x86/kernel/apic_32.c @@ -424,6 +424,90 @@ static void __cpuinit setup_APIC_timer(void) clockevents_register_device(levt); } +#ifdef CONFIG_X86_64 +/* + * In this function we calibrate APIC bus clocks to the external + * timer. Unfortunately we cannot use jiffies and the timer irq + * to calibrate, since some later bootup code depends on getting + * the first irq? Ugh. + * + * We want to do the calibration only once since we + * want to have local timer irqs syncron. CPUs connected + * by the same APIC bus have the very same bus frequency. + * And we want to have irqs off anyways, no accidental + * APIC irq that way. + */ + +#define TICK_COUNT 100000000 + +static int __init calibrate_APIC_clock(void) +{ + unsigned apic, apic_start; + unsigned long tsc, tsc_start; + int result; + + local_irq_disable(); + + /* + * Put whatever arbitrary (but long enough) timeout + * value into the APIC clock, we just want to get the + * counter running for calibration. + * + * No interrupt enable ! + */ + __setup_APIC_LVTT(250000000, 0, 0); + + apic_start = apic_read(APIC_TMCCT); +#ifdef CONFIG_X86_PM_TIMER + if (apic_calibrate_pmtmr && pmtmr_ioport) { + pmtimer_wait(5000); /* 5ms wait */ + apic = apic_read(APIC_TMCCT); + result = (apic_start - apic) * 1000L / 5; + } else +#endif + { + rdtscll(tsc_start); + + do { + apic = apic_read(APIC_TMCCT); + rdtscll(tsc); + } while ((tsc - tsc_start) < TICK_COUNT && + (apic_start - apic) < TICK_COUNT); + + result = (apic_start - apic) * 1000L * tsc_khz / + (tsc - tsc_start); + } + + local_irq_enable(); + + printk(KERN_DEBUG "APIC timer calibration result %d\n", result); + + printk(KERN_INFO "Detected %d.%03d MHz APIC timer.\n", + result / 1000 / 1000, result / 1000 % 1000); + + /* Calculate the scaled math multiplication factor */ + lapic_clockevent.mult = div_sc(result, NSEC_PER_SEC, + lapic_clockevent.shift); + lapic_clockevent.max_delta_ns = + clockevent_delta2ns(0x7FFFFF, &lapic_clockevent); + lapic_clockevent.min_delta_ns = + clockevent_delta2ns(0xF, &lapic_clockevent); + + calibration_result = (result * APIC_DIVISOR) / HZ; + + /* + * Do a sanity check on the APIC calibration result + */ + if (calibration_result < (1000000 / HZ)) { + printk(KERN_WARNING + "APIC frequency too slow, disabling apic timer\n"); + return -1; + } + + return 0; +} + +#else /* * In this functions we calibrate APIC bus clocks to the external timer. * @@ -635,6 +719,8 @@ static int __init calibrate_APIC_clock(void) return 0; } +#endif + /* * Setup the boot APIC * diff --git a/arch/x86/kernel/apic_64.c b/arch/x86/kernel/apic_64.c index c728885..6e99af5 100644 --- a/arch/x86/kernel/apic_64.c +++ b/arch/x86/kernel/apic_64.c @@ -478,6 +478,7 @@ static void __cpuinit setup_APIC_timer(void) clockevents_register_device(levt); } +#ifdef CONFIG_X86_64 /* * In this function we calibrate APIC bus clocks to the external * timer. Unfortunately we cannot use jiffies and the timer irq @@ -560,6 +561,220 @@ static int __init calibrate_APIC_clock(void) return 0; } +#else +/* + * In this functions we calibrate APIC bus clocks to the external timer. + * + * We want to do the calibration only once since we want to have local timer + * irqs syncron. CPUs connected by the same APIC bus have the very same bus + * frequency. + * + * This was previously done by reading the PIT/HPET and waiting for a wrap + * around to find out, that a tick has elapsed. I have a box, where the PIT + * readout is broken, so it never gets out of the wait loop again. This was + * also reported by others. + * + * Monitoring the jiffies value is inaccurate and the clockevents + * infrastructure allows us to do a simple substitution of the interrupt + * handler. + * + * The calibration routine also uses the pm_timer when possible, as the PIT + * happens to run way too slow (factor 2.3 on my VAIO CoreDuo, which goes + * back to normal later in the boot process). + */ + +#define LAPIC_CAL_LOOPS (HZ/10) + +static __initdata int lapic_cal_loops = -1; +static __initdata long lapic_cal_t1, lapic_cal_t2; +static __initdata unsigned long long lapic_cal_tsc1, lapic_cal_tsc2; +static __initdata unsigned long lapic_cal_pm1, lapic_cal_pm2; +static __initdata unsigned long lapic_cal_j1, lapic_cal_j2; + +/* + * Temporary interrupt handler. + */ +static void __init lapic_cal_handler(struct clock_event_device *dev) +{ + unsigned long long tsc = 0; + long tapic = apic_read(APIC_TMCCT); + unsigned long pm = acpi_pm_read_early(); + + if (cpu_has_tsc) + rdtscll(tsc); + + switch (lapic_cal_loops++) { + case 0: + lapic_cal_t1 = tapic; + lapic_cal_tsc1 = tsc; + lapic_cal_pm1 = pm; + lapic_cal_j1 = jiffies; + break; + + case LAPIC_CAL_LOOPS: + lapic_cal_t2 = tapic; + lapic_cal_tsc2 = tsc; + if (pm < lapic_cal_pm1) + pm += ACPI_PM_OVRRUN; + lapic_cal_pm2 = pm; + lapic_cal_j2 = jiffies; + break; + } +} + +static int __init calibrate_APIC_clock(void) +{ + struct clock_event_device *levt = &__get_cpu_var(lapic_events); + const long pm_100ms = PMTMR_TICKS_PER_SEC/10; + const long pm_thresh = pm_100ms/100; + void (*real_handler)(struct clock_event_device *dev); + unsigned long deltaj; + long delta, deltapm; + int pm_referenced = 0; + + local_irq_disable(); + + /* Replace the global interrupt handler */ + real_handler = global_clock_event->event_handler; + global_clock_event->event_handler = lapic_cal_handler; + + /* + * Setup the APIC counter to 1e9. There is no way the lapic + * can underflow in the 100ms detection time frame + */ + __setup_APIC_LVTT(1000000000, 0, 0); + + /* Let the interrupts run */ + local_irq_enable(); + + while (lapic_cal_loops <= LAPIC_CAL_LOOPS) + cpu_relax(); + + local_irq_disable(); + + /* Restore the real event handler */ + global_clock_event->event_handler = real_handler; + + /* Build delta t1-t2 as apic timer counts down */ + delta = lapic_cal_t1 - lapic_cal_t2; + apic_printk(APIC_VERBOSE, "... lapic delta = %ld\n", delta); + + /* Check, if the PM timer is available */ + deltapm = lapic_cal_pm2 - lapic_cal_pm1; + apic_printk(APIC_VERBOSE, "... PM timer delta = %ld\n", deltapm); + + if (deltapm) { + unsigned long mult; + u64 res; + + mult = clocksource_hz2mult(PMTMR_TICKS_PER_SEC, 22); + + if (deltapm > (pm_100ms - pm_thresh) && + deltapm < (pm_100ms + pm_thresh)) { + apic_printk(APIC_VERBOSE, "... PM timer result ok\n"); + } else { + res = (((u64) deltapm) * mult) >> 22; + do_div(res, 1000000); + printk(KERN_WARNING "APIC calibration not consistent " + "with PM Timer: %ldms instead of 100ms\n", + (long)res); + /* Correct the lapic counter value */ + res = (((u64) delta) * pm_100ms); + do_div(res, deltapm); + printk(KERN_INFO "APIC delta adjusted to PM-Timer: " + "%lu (%ld)\n", (unsigned long) res, delta); + delta = (long) res; + } + pm_referenced = 1; + } + + /* Calculate the scaled math multiplication factor */ + lapic_clockevent.mult = div_sc(delta, TICK_NSEC * LAPIC_CAL_LOOPS, + lapic_clockevent.shift); + lapic_clockevent.max_delta_ns = + clockevent_delta2ns(0x7FFFFF, &lapic_clockevent); + lapic_clockevent.min_delta_ns = + clockevent_delta2ns(0xF, &lapic_clockevent); + + calibration_result = (delta * APIC_DIVISOR) / LAPIC_CAL_LOOPS; + + apic_printk(APIC_VERBOSE, "..... delta %ld\n", delta); + apic_printk(APIC_VERBOSE, "..... mult: %ld\n", lapic_clockevent.mult); + apic_printk(APIC_VERBOSE, "..... calibration result: %u\n", + calibration_result); + + if (cpu_has_tsc) { + delta = (long)(lapic_cal_tsc2 - lapic_cal_tsc1); + apic_printk(APIC_VERBOSE, "..... CPU clock speed is " + "%ld.%04ld MHz.\n", + (delta / LAPIC_CAL_LOOPS) / (1000000 / HZ), + (delta / LAPIC_CAL_LOOPS) % (1000000 / HZ)); + } + + apic_printk(APIC_VERBOSE, "..... host bus clock speed is " + "%u.%04u MHz.\n", + calibration_result / (1000000 / HZ), + calibration_result % (1000000 / HZ)); + + /* + * Do a sanity check on the APIC calibration result + */ + if (calibration_result < (1000000 / HZ)) { + local_irq_enable(); + printk(KERN_WARNING + "APIC frequency too slow, disabling apic timer\n"); + return -1; + } + + levt->features &= ~CLOCK_EVT_FEAT_DUMMY; + + /* We trust the pm timer based calibration */ + if (!pm_referenced) { + apic_printk(APIC_VERBOSE, "... verify APIC timer\n"); + + /* + * Setup the apic timer manually + */ + levt->event_handler = lapic_cal_handler; + lapic_timer_setup(CLOCK_EVT_MODE_PERIODIC, levt); + lapic_cal_loops = -1; + + /* Let the interrupts run */ + local_irq_enable(); + + while (lapic_cal_loops <= LAPIC_CAL_LOOPS) + cpu_relax(); + + local_irq_disable(); + + /* Stop the lapic timer */ + lapic_timer_setup(CLOCK_EVT_MODE_SHUTDOWN, levt); + + local_irq_enable(); + + /* Jiffies delta */ + deltaj = lapic_cal_j2 - lapic_cal_j1; + apic_printk(APIC_VERBOSE, "... jiffies delta = %lu\n", deltaj); + + /* Check, if the jiffies result is consistent */ + if (deltaj >= LAPIC_CAL_LOOPS-2 && deltaj <= LAPIC_CAL_LOOPS+2) + apic_printk(APIC_VERBOSE, "... jiffies result ok\n"); + else + levt->features |= CLOCK_EVT_FEAT_DUMMY; + } else + local_irq_enable(); + + if (levt->features & CLOCK_EVT_FEAT_DUMMY) { + printk(KERN_WARNING + "APIC timer disabled due to verification failure.\n"); + return -1; + } + + return 0; +} + +#endif + /* * Setup the boot APIC * |