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