/*
* The guts of the apic timer interrupt
*/
static void local_apic_timer_interrupt(void)
{
int cpu = smp_processor_id();
struct clock_event_device *evt = &per_cpu(lapic_events, cpu);
/*
* Normally we should not be here till LAPIC has been initialized but
* in some cases like kdump, its possible that there is a pending LAPIC
* timer interrupt from previous kernel's context and is delivered in
* new kernel the moment interrupts are enabled.
*
* Interrupts are enabled early and LAPIC is setup much later, hence
* its possible that when we get here evt->event_handler is NULL.
* Check for event_handler being NULL and discard the interrupt as
* spurious.
*/
if (!evt->event_handler) {
printk(KERN_WARNING
"Spurious LAPIC timer interrupt on cpu %d\n", cpu);
/* Switch it off */
lapic_timer_setup(CLOCK_EVT_MODE_SHUTDOWN, evt);
return;
}
/*
* the NMI deadlock-detector uses this.
*/
add_pda(apic_timer_irqs, 1);
evt->event_handler(evt);
}
static void local_apic_timer_interrupt(void)
{
int cpu = smp_processor_id();
struct clock_event_device *evt = &per_cpu(lapic_events, cpu);
if (!evt->event_handler) {
pr_warning("Spurious LAPIC timer interrupt on cpu %d\n", cpu);
lapic_timer_setup(CLOCK_EVT_MODE_SHUTDOWN, evt);
return;
}
inc_irq_stat(apic_timer_irqs);
evt->event_handler(evt);
}
static int __init calibrate_APIC_clock(void)
{
struct clock_event_device *levt = &__get_cpu_var(lapic_events);
void (*real_handler)(struct clock_event_device *dev);
unsigned long deltaj;
long delta, deltatsc;
int pm_referenced = 0;
local_irq_disable();
real_handler = global_clock_event->event_handler;
global_clock_event->event_handler = lapic_cal_handler;
__setup_APIC_LVTT(0xffffffff, 0, 0);
local_irq_enable();
while (lapic_cal_loops <= LAPIC_CAL_LOOPS)
cpu_relax();
local_irq_disable();
global_clock_event->event_handler = real_handler;
delta = lapic_cal_t1 - lapic_cal_t2;
apic_printk(APIC_VERBOSE, "... lapic delta = %ld\n", delta);
deltatsc = (long)(lapic_cal_tsc2 - lapic_cal_tsc1);
pm_referenced = !calibrate_by_pmtimer(lapic_cal_pm2 - lapic_cal_pm1,
&delta, &deltatsc);
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) {
apic_printk(APIC_VERBOSE, "..... CPU clock speed is "
"%ld.%04ld MHz.\n",
(deltatsc / LAPIC_CAL_LOOPS) / (1000000 / HZ),
(deltatsc / 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));
if (calibration_result < (1000000 / HZ)) {
local_irq_enable();
pr_warning("APIC frequency too slow, disabling apic timer\n");
return -1;
}
levt->features &= ~CLOCK_EVT_FEAT_DUMMY;
if (!pm_referenced) {
apic_printk(APIC_VERBOSE, "... verify APIC timer\n");
levt->event_handler = lapic_cal_handler;
lapic_timer_setup(CLOCK_EVT_MODE_PERIODIC, levt);
lapic_cal_loops = -1;
local_irq_enable();
while (lapic_cal_loops <= LAPIC_CAL_LOOPS)
cpu_relax();
lapic_timer_setup(CLOCK_EVT_MODE_SHUTDOWN, levt);
deltaj = lapic_cal_j2 - lapic_cal_j1;
apic_printk(APIC_VERBOSE, "... jiffies delta = %lu\n", deltaj);
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) {
pr_warning("APIC timer disabled due to verification failure\n");
return -1;
}
return 0;
}
/*
* Setup the boot APIC
*
* Calibrate and verify the result.
*/
void __init setup_boot_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;
apic_printk(APIC_VERBOSE, "Using local APIC timer interrupts.\n"
"calibrating APIC timer ...\n");
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, 32);
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));
local_apic_timer_verify_ok = 1;
/* 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
local_apic_timer_verify_ok = 0;
}
if (!local_apic_timer_verify_ok) {
printk(KERN_WARNING
"APIC timer disabled due to verification failure.\n");
/* No broadcast on UP ! */
if (num_possible_cpus() == 1)
return;
} else {
/*
* If nmi_watchdog is set to IO_APIC, we need the
* PIT/HPET going. Otherwise register lapic as a dummy
* device.
*/
if (nmi_watchdog != NMI_IO_APIC)
lapic_clockevent.features &= ~CLOCK_EVT_FEAT_DUMMY;
}
/* Setup the lapic or request the broadcast */
setup_APIC_timer();
}
