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linux-stable-rt/arch/x86_64/kernel/time.c

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/*
* linux/arch/x86-64/kernel/time.c
*
* "High Precision Event Timer" based timekeeping.
*
* Copyright (c) 1991,1992,1995 Linus Torvalds
* Copyright (c) 1994 Alan Modra
* Copyright (c) 1995 Markus Kuhn
* Copyright (c) 1996 Ingo Molnar
* Copyright (c) 1998 Andrea Arcangeli
* Copyright (c) 2002,2006 Vojtech Pavlik
* Copyright (c) 2003 Andi Kleen
* RTC support code taken from arch/i386/kernel/timers/time_hpet.c
*/
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/mc146818rtc.h>
#include <linux/time.h>
#include <linux/ioport.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/sysdev.h>
#include <linux/bcd.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
#include <linux/kallsyms.h>
#include <linux/acpi.h>
#ifdef CONFIG_ACPI
#include <acpi/achware.h> /* for PM timer frequency */
#include <acpi/acpi_bus.h>
#endif
#include <asm/8253pit.h>
#include <asm/pgtable.h>
#include <asm/vsyscall.h>
#include <asm/timex.h>
#include <asm/proto.h>
#include <asm/hpet.h>
#include <asm/sections.h>
#include <linux/hpet.h>
#include <asm/apic.h>
#include <asm/hpet.h>
#include <asm/mpspec.h>
#include <asm/nmi.h>
static char *timename = NULL;
DEFINE_SPINLOCK(rtc_lock);
EXPORT_SYMBOL(rtc_lock);
DEFINE_SPINLOCK(i8253_lock);
volatile unsigned long __jiffies __section_jiffies = INITIAL_JIFFIES;
unsigned long profile_pc(struct pt_regs *regs)
{
unsigned long pc = instruction_pointer(regs);
/* Assume the lock function has either no stack frame or a copy
of eflags from PUSHF
Eflags always has bits 22 and up cleared unlike kernel addresses. */
if (!user_mode(regs) && in_lock_functions(pc)) {
unsigned long *sp = (unsigned long *)regs->rsp;
if (sp[0] >> 22)
return sp[0];
if (sp[1] >> 22)
return sp[1];
}
return pc;
}
EXPORT_SYMBOL(profile_pc);
/*
* In order to set the CMOS clock precisely, set_rtc_mmss has to be called 500
* ms after the second nowtime has started, because when nowtime is written
* into the registers of the CMOS clock, it will jump to the next second
* precisely 500 ms later. Check the Motorola MC146818A or Dallas DS12887 data
* sheet for details.
*/
static void set_rtc_mmss(unsigned long nowtime)
{
int real_seconds, real_minutes, cmos_minutes;
unsigned char control, freq_select;
/*
* IRQs are disabled when we're called from the timer interrupt,
* no need for spin_lock_irqsave()
*/
spin_lock(&rtc_lock);
/*
* Tell the clock it's being set and stop it.
*/
control = CMOS_READ(RTC_CONTROL);
CMOS_WRITE(control | RTC_SET, RTC_CONTROL);
freq_select = CMOS_READ(RTC_FREQ_SELECT);
CMOS_WRITE(freq_select | RTC_DIV_RESET2, RTC_FREQ_SELECT);
cmos_minutes = CMOS_READ(RTC_MINUTES);
BCD_TO_BIN(cmos_minutes);
/*
* since we're only adjusting minutes and seconds, don't interfere with hour
* overflow. This avoids messing with unknown time zones but requires your RTC
* not to be off by more than 15 minutes. Since we're calling it only when
* our clock is externally synchronized using NTP, this shouldn't be a problem.
*/
real_seconds = nowtime % 60;
real_minutes = nowtime / 60;
if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1)
real_minutes += 30; /* correct for half hour time zone */
real_minutes %= 60;
if (abs(real_minutes - cmos_minutes) >= 30) {
printk(KERN_WARNING "time.c: can't update CMOS clock "
"from %d to %d\n", cmos_minutes, real_minutes);
} else {
BIN_TO_BCD(real_seconds);
BIN_TO_BCD(real_minutes);
CMOS_WRITE(real_seconds, RTC_SECONDS);
CMOS_WRITE(real_minutes, RTC_MINUTES);
}
/*
* The following flags have to be released exactly in this order, otherwise the
* DS12887 (popular MC146818A clone with integrated battery and quartz) will
* not reset the oscillator and will not update precisely 500 ms later. You
* won't find this mentioned in the Dallas Semiconductor data sheets, but who
* believes data sheets anyway ... -- Markus Kuhn
*/
CMOS_WRITE(control, RTC_CONTROL);
CMOS_WRITE(freq_select, RTC_FREQ_SELECT);
spin_unlock(&rtc_lock);
}
void main_timer_handler(void)
{
static unsigned long rtc_update = 0;
/*
* Here we are in the timer irq handler. We have irqs locally disabled (so we
* don't need spin_lock_irqsave()) but we don't know if the timer_bh is running
* on the other CPU, so we need a lock. We also need to lock the vsyscall
* variables, because both do_timer() and us change them -arca+vojtech
*/
write_seqlock(&xtime_lock);
/*
* Do the timer stuff.
*/
do_timer(1);
#ifndef CONFIG_SMP
update_process_times(user_mode(get_irq_regs()));
#endif
/*
* In the SMP case we use the local APIC timer interrupt to do the profiling,
* except when we simulate SMP mode on a uniprocessor system, in that case we
* have to call the local interrupt handler.
*/
if (!using_apic_timer)
smp_local_timer_interrupt();
/*
* If we have an externally synchronized Linux clock, then update CMOS clock
* accordingly every ~11 minutes. set_rtc_mmss() will be called in the jiffy
* closest to exactly 500 ms before the next second. If the update fails, we
* don't care, as it'll be updated on the next turn, and the problem (time way
* off) isn't likely to go away much sooner anyway.
*/
if (ntp_synced() && xtime.tv_sec > rtc_update &&
abs(xtime.tv_nsec - 500000000) <= tick_nsec / 2) {
set_rtc_mmss(xtime.tv_sec);
rtc_update = xtime.tv_sec + 660;
}
write_sequnlock(&xtime_lock);
}
static irqreturn_t timer_interrupt(int irq, void *dev_id)
{
if (apic_runs_main_timer > 1)
return IRQ_HANDLED;
main_timer_handler();
if (using_apic_timer)
smp_send_timer_broadcast_ipi();
return IRQ_HANDLED;
}
static unsigned long get_cmos_time(void)
{
unsigned int year, mon, day, hour, min, sec;
unsigned long flags;
unsigned century = 0;
spin_lock_irqsave(&rtc_lock, flags);
do {
sec = CMOS_READ(RTC_SECONDS);
min = CMOS_READ(RTC_MINUTES);
hour = CMOS_READ(RTC_HOURS);
day = CMOS_READ(RTC_DAY_OF_MONTH);
mon = CMOS_READ(RTC_MONTH);
year = CMOS_READ(RTC_YEAR);
#ifdef CONFIG_ACPI
if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
acpi_gbl_FADT.century)
century = CMOS_READ(acpi_gbl_FADT.century);
#endif
} while (sec != CMOS_READ(RTC_SECONDS));
spin_unlock_irqrestore(&rtc_lock, flags);
/*
* We know that x86-64 always uses BCD format, no need to check the
* config register.
*/
BCD_TO_BIN(sec);
BCD_TO_BIN(min);
BCD_TO_BIN(hour);
BCD_TO_BIN(day);
BCD_TO_BIN(mon);
BCD_TO_BIN(year);
if (century) {
BCD_TO_BIN(century);
year += century * 100;
printk(KERN_INFO "Extended CMOS year: %d\n", century * 100);
} else {
/*
* x86-64 systems only exists since 2002.
* This will work up to Dec 31, 2100
*/
year += 2000;
}
return mktime(year, mon, day, hour, min, sec);
}
/* calibrate_cpu is used on systems with fixed rate TSCs to determine
* processor frequency */
#define TICK_COUNT 100000000
static unsigned int __init tsc_calibrate_cpu_khz(void)
{
int tsc_start, tsc_now;
int i, no_ctr_free;
unsigned long evntsel3 = 0, pmc3 = 0, pmc_now = 0;
unsigned long flags;
for (i = 0; i < 4; i++)
if (avail_to_resrv_perfctr_nmi_bit(i))
break;
no_ctr_free = (i == 4);
if (no_ctr_free) {
i = 3;
rdmsrl(MSR_K7_EVNTSEL3, evntsel3);
wrmsrl(MSR_K7_EVNTSEL3, 0);
rdmsrl(MSR_K7_PERFCTR3, pmc3);
} else {
reserve_perfctr_nmi(MSR_K7_PERFCTR0 + i);
reserve_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
}
local_irq_save(flags);
/* start meauring cycles, incrementing from 0 */
wrmsrl(MSR_K7_PERFCTR0 + i, 0);
wrmsrl(MSR_K7_EVNTSEL0 + i, 1 << 22 | 3 << 16 | 0x76);
rdtscl(tsc_start);
do {
rdmsrl(MSR_K7_PERFCTR0 + i, pmc_now);
tsc_now = get_cycles_sync();
} while ((tsc_now - tsc_start) < TICK_COUNT);
local_irq_restore(flags);
if (no_ctr_free) {
wrmsrl(MSR_K7_EVNTSEL3, 0);
wrmsrl(MSR_K7_PERFCTR3, pmc3);
wrmsrl(MSR_K7_EVNTSEL3, evntsel3);
} else {
release_perfctr_nmi(MSR_K7_PERFCTR0 + i);
release_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
}
return pmc_now * tsc_khz / (tsc_now - tsc_start);
}
/*
* pit_calibrate_tsc() uses the speaker output (channel 2) of
* the PIT. This is better than using the timer interrupt output,
* because we can read the value of the speaker with just one inb(),
* where we need three i/o operations for the interrupt channel.
* We count how many ticks the TSC does in 50 ms.
*/
static unsigned int __init pit_calibrate_tsc(void)
{
unsigned long start, end;
unsigned long flags;
spin_lock_irqsave(&i8253_lock, flags);
outb((inb(0x61) & ~0x02) | 0x01, 0x61);
outb(0xb0, 0x43);
outb((PIT_TICK_RATE / (1000 / 50)) & 0xff, 0x42);
outb((PIT_TICK_RATE / (1000 / 50)) >> 8, 0x42);
start = get_cycles_sync();
while ((inb(0x61) & 0x20) == 0);
end = get_cycles_sync();
spin_unlock_irqrestore(&i8253_lock, flags);
return (end - start) / 50;
}
#define PIT_MODE 0x43
#define PIT_CH0 0x40
static void __pit_init(int val, u8 mode)
{
unsigned long flags;
spin_lock_irqsave(&i8253_lock, flags);
outb_p(mode, PIT_MODE);
outb_p(val & 0xff, PIT_CH0); /* LSB */
outb_p(val >> 8, PIT_CH0); /* MSB */
spin_unlock_irqrestore(&i8253_lock, flags);
}
void __init pit_init(void)
{
__pit_init(LATCH, 0x34); /* binary, mode 2, LSB/MSB, ch 0 */
}
void pit_stop_interrupt(void)
{
__pit_init(0, 0x30); /* mode 0 */
}
void stop_timer_interrupt(void)
{
char *name;
if (hpet_address) {
name = "HPET";
hpet_timer_stop_set_go(0);
} else {
name = "PIT";
pit_stop_interrupt();
}
printk(KERN_INFO "timer: %s interrupt stopped.\n", name);
}
static struct irqaction irq0 = {
.handler = timer_interrupt,
.flags = IRQF_DISABLED | IRQF_IRQPOLL,
.mask = CPU_MASK_NONE,
.name = "timer"
};
void __init time_init(void)
{
if (nohpet)
hpet_address = 0;
xtime.tv_sec = get_cmos_time();
xtime.tv_nsec = 0;
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
if (hpet_arch_init())
hpet_address = 0;
if (hpet_use_timer) {
/* set tick_nsec to use the proper rate for HPET */
tick_nsec = TICK_NSEC_HPET;
tsc_khz = hpet_calibrate_tsc();
timename = "HPET";
} else {
pit_init();
tsc_khz = pit_calibrate_tsc();
timename = "PIT";
}
cpu_khz = tsc_khz;
if (cpu_has(&boot_cpu_data, X86_FEATURE_CONSTANT_TSC) &&
boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
boot_cpu_data.x86 == 16)
cpu_khz = tsc_calibrate_cpu_khz();
if (unsynchronized_tsc())
mark_tsc_unstable("TSCs unsynchronized");
if (cpu_has(&boot_cpu_data, X86_FEATURE_RDTSCP))
vgetcpu_mode = VGETCPU_RDTSCP;
else
vgetcpu_mode = VGETCPU_LSL;
set_cyc2ns_scale(tsc_khz);
printk(KERN_INFO "time.c: Detected %d.%03d MHz processor.\n",
cpu_khz / 1000, cpu_khz % 1000);
init_tsc_clocksource();
setup_irq(0, &irq0);
}
static long clock_cmos_diff;
static unsigned long sleep_start;
/*
* sysfs support for the timer.
*/
static int timer_suspend(struct sys_device *dev, pm_message_t state)
{
/*
* Estimate time zone so that set_time can update the clock
*/
long cmos_time = get_cmos_time();
clock_cmos_diff = -cmos_time;
clock_cmos_diff += get_seconds();
sleep_start = cmos_time;
return 0;
}
static int timer_resume(struct sys_device *dev)
{
unsigned long flags;
unsigned long sec;
unsigned long ctime = get_cmos_time();
long sleep_length = (ctime - sleep_start) * HZ;
if (sleep_length < 0) {
printk(KERN_WARNING "Time skew detected in timer resume!\n");
/* The time after the resume must not be earlier than the time
* before the suspend or some nasty things will happen
*/
sleep_length = 0;
ctime = sleep_start;
}
if (hpet_address)
hpet_reenable();
else
i8254_timer_resume();
sec = ctime + clock_cmos_diff;
write_seqlock_irqsave(&xtime_lock,flags);
xtime.tv_sec = sec;
xtime.tv_nsec = 0;
jiffies += sleep_length;
write_sequnlock_irqrestore(&xtime_lock,flags);
touch_softlockup_watchdog();
return 0;
}
static struct sysdev_class timer_sysclass = {
.resume = timer_resume,
.suspend = timer_suspend,
set_kset_name("timer"),
};
/* XXX this sysfs stuff should probably go elsewhere later -john */
static struct sys_device device_timer = {
.id = 0,
.cls = &timer_sysclass,
};
static int time_init_device(void)
{
int error = sysdev_class_register(&timer_sysclass);
if (!error)
error = sysdev_register(&device_timer);
return error;
}
device_initcall(time_init_device);
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