/* * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_ACPI #include /* for PM timer frequency */ #include #endif #include #include #include #include #include #include #include #include #include #include #include #include #include DEFINE_SPINLOCK(rtc_lock); EXPORT_SYMBOL(rtc_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 int set_rtc_mmss(unsigned long nowtime) { int retval = 0; 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); retval = -1; } 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); return retval; } int update_persistent_clock(struct timespec now) { return set_rtc_mmss(now.tv_sec); } void main_timer_handler(void) { /* * 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(); 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 irqreturn_t timer_event_interrupt(int irq, void *dev_id) { global_clock_event->event_handler(global_clock_event); return IRQ_HANDLED; } unsigned long read_persistent_clock(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); } static struct irqaction irq0 = { .handler = timer_event_interrupt, .flags = IRQF_DISABLED | IRQF_IRQPOLL | IRQF_NOBALANCING, .mask = CPU_MASK_NONE, .name = "timer" }; void __init time_init(void) { if (!hpet_enable()) setup_pit_timer(); setup_irq(0, &irq0); tsc_calibrate(); 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(); }