/* * linux/arch/i386/kernel/time.c * * Copyright (C) 1991, 1992, 1995 Linus Torvalds * * This file contains the PC-specific time handling details: * reading the RTC at bootup, etc.. * 1994-07-02 Alan Modra * fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime * 1995-03-26 Markus Kuhn * fixed 500 ms bug at call to set_rtc_mmss, fixed DS12887 * precision CMOS clock update * 1996-05-03 Ingo Molnar * fixed time warps in do_[slow|fast]_gettimeoffset() * 1997-09-10 Updated NTP code according to technical memorandum Jan '96 * "A Kernel Model for Precision Timekeeping" by Dave Mills * 1998-09-05 (Various) * More robust do_fast_gettimeoffset() algorithm implemented * (works with APM, Cyrix 6x86MX and Centaur C6), * monotonic gettimeofday() with fast_get_timeoffset(), * drift-proof precision TSC calibration on boot * (C. Scott Ananian , Andrew D. * Balsa , Philip Gladstone ; * ported from 2.0.35 Jumbo-9 by Michael Krause ). * 1998-12-16 Andrea Arcangeli * Fixed Jumbo-9 code in 2.1.131: do_gettimeofday was missing 1 jiffy * because was not accounting lost_ticks. * 1998-12-24 Copyright (C) 1998 Andrea Arcangeli * Fixed a xtime SMP race (we need the xtime_lock rw spinlock to * serialize accesses to xtime/lost_ticks). */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "mach_time.h" #include #include #include #include #include "io_ports.h" #include int pit_latch_buggy; /* extern */ #include "do_timer.h" u64 jiffies_64 = INITIAL_JIFFIES; EXPORT_SYMBOL(jiffies_64); unsigned int cpu_khz; /* Detected as we calibrate the TSC */ EXPORT_SYMBOL(cpu_khz); extern unsigned long wall_jiffies; DEFINE_SPINLOCK(rtc_lock); EXPORT_SYMBOL(rtc_lock); #include DEFINE_SPINLOCK(i8253_lock); EXPORT_SYMBOL(i8253_lock); struct timer_opts *cur_timer __read_mostly = &timer_none; /* * This is a special lock that is owned by the CPU and holds the index * register we are working with. It is required for NMI access to the * CMOS/RTC registers. See include/asm-i386/mc146818rtc.h for details. */ volatile unsigned long cmos_lock = 0; EXPORT_SYMBOL(cmos_lock); /* Routines for accessing the CMOS RAM/RTC. */ unsigned char rtc_cmos_read(unsigned char addr) { unsigned char val; lock_cmos_prefix(addr); outb_p(addr, RTC_PORT(0)); val = inb_p(RTC_PORT(1)); lock_cmos_suffix(addr); return val; } EXPORT_SYMBOL(rtc_cmos_read); void rtc_cmos_write(unsigned char val, unsigned char addr) { lock_cmos_prefix(addr); outb_p(addr, RTC_PORT(0)); outb_p(val, RTC_PORT(1)); lock_cmos_suffix(addr); } EXPORT_SYMBOL(rtc_cmos_write); /* * This version of gettimeofday has microsecond resolution * and better than microsecond precision on fast x86 machines with TSC. */ void do_gettimeofday(struct timeval *tv) { unsigned long seq; unsigned long usec, sec; unsigned long max_ntp_tick; do { unsigned long lost; seq = read_seqbegin(&xtime_lock); usec = cur_timer->get_offset(); lost = jiffies - wall_jiffies; /* * If time_adjust is negative then NTP is slowing the clock * so make sure not to go into next possible interval. * Better to lose some accuracy than have time go backwards.. */ if (unlikely(time_adjust < 0)) { max_ntp_tick = (USEC_PER_SEC / HZ) - tickadj; usec = min(usec, max_ntp_tick); if (lost) usec += lost * max_ntp_tick; } else if (unlikely(lost)) usec += lost * (USEC_PER_SEC / HZ); sec = xtime.tv_sec; usec += (xtime.tv_nsec / 1000); } while (read_seqretry(&xtime_lock, seq)); while (usec >= 1000000) { usec -= 1000000; sec++; } tv->tv_sec = sec; tv->tv_usec = usec; } EXPORT_SYMBOL(do_gettimeofday); int do_settimeofday(struct timespec *tv) { time_t wtm_sec, sec = tv->tv_sec; long wtm_nsec, nsec = tv->tv_nsec; if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) return -EINVAL; write_seqlock_irq(&xtime_lock); /* * This is revolting. We need to set "xtime" correctly. However, the * value in this location is the value at the most recent update of * wall time. Discover what correction gettimeofday() would have * made, and then undo it! */ nsec -= cur_timer->get_offset() * NSEC_PER_USEC; nsec -= (jiffies - wall_jiffies) * TICK_NSEC; wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec); wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec); set_normalized_timespec(&xtime, sec, nsec); set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec); ntp_clear(); write_sequnlock_irq(&xtime_lock); clock_was_set(); return 0; } EXPORT_SYMBOL(do_settimeofday); static int set_rtc_mmss(unsigned long nowtime) { int retval; WARN_ON(irqs_disabled()); /* gets recalled with irq locally disabled */ spin_lock_irq(&rtc_lock); if (efi_enabled) retval = efi_set_rtc_mmss(nowtime); else retval = mach_set_rtc_mmss(nowtime); spin_unlock_irq(&rtc_lock); return retval; } int timer_ack; /* monotonic_clock(): returns # of nanoseconds passed since time_init() * Note: This function is required to return accurate * time even in the absence of multiple timer ticks. */ unsigned long long monotonic_clock(void) { return cur_timer->monotonic_clock(); } EXPORT_SYMBOL(monotonic_clock); #if defined(CONFIG_SMP) && defined(CONFIG_FRAME_POINTER) unsigned long profile_pc(struct pt_regs *regs) { unsigned long pc = instruction_pointer(regs); if (in_lock_functions(pc)) return *(unsigned long *)(regs->ebp + 4); return pc; } EXPORT_SYMBOL(profile_pc); #endif /* * timer_interrupt() needs to keep up the real-time clock, * as well as call the "do_timer()" routine every clocktick */ static inline void do_timer_interrupt(int irq, struct pt_regs *regs) { #ifdef CONFIG_X86_IO_APIC if (timer_ack) { /* * Subtle, when I/O APICs are used we have to ack timer IRQ * manually to reset the IRR bit for do_slow_gettimeoffset(). * This will also deassert NMI lines for the watchdog if run * on an 82489DX-based system. */ spin_lock(&i8259A_lock); outb(0x0c, PIC_MASTER_OCW3); /* Ack the IRQ; AEOI will end it automatically. */ inb(PIC_MASTER_POLL); spin_unlock(&i8259A_lock); } #endif do_timer_interrupt_hook(regs); if (MCA_bus) { /* The PS/2 uses level-triggered interrupts. You can't turn them off, nor would you want to (any attempt to enable edge-triggered interrupts usually gets intercepted by a special hardware circuit). Hence we have to acknowledge the timer interrupt. Through some incredibly stupid design idea, the reset for IRQ 0 is done by setting the high bit of the PPI port B (0x61). Note that some PS/2s, notably the 55SX, work fine if this is removed. */ irq = inb_p( 0x61 ); /* read the current state */ outb_p( irq|0x80, 0x61 ); /* reset the IRQ */ } } /* * This is the same as the above, except we _also_ save the current * Time Stamp Counter value at the time of the timer interrupt, so that * we later on can estimate the time of day more exactly. */ irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) { /* * Here we are in the timer irq handler. We just have irqs locally * disabled but we don't know if the timer_bh is running on the other * CPU. We need to avoid to SMP race with it. NOTE: we don' t need * the irq version of write_lock because as just said we have irq * locally disabled. -arca */ write_seqlock(&xtime_lock); cur_timer->mark_offset(); do_timer_interrupt(irq, regs); write_sequnlock(&xtime_lock); return IRQ_HANDLED; } /* not static: needed by APM */ unsigned long get_cmos_time(void) { unsigned long retval; spin_lock(&rtc_lock); if (efi_enabled) retval = efi_get_time(); else retval = mach_get_cmos_time(); spin_unlock(&rtc_lock); return retval; } EXPORT_SYMBOL(get_cmos_time); static void sync_cmos_clock(unsigned long dummy); static struct timer_list sync_cmos_timer = TIMER_INITIALIZER(sync_cmos_clock, 0, 0); static void sync_cmos_clock(unsigned long dummy) { struct timeval now, next; int fail = 1; /* * If we have an externally synchronized Linux clock, then update * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be * called as close as possible to 500 ms before the new second starts. * This code is run on a timer. If the clock is set, that timer * may not expire at the correct time. Thus, we adjust... */ if (!ntp_synced()) /* * Not synced, exit, do not restart a timer (if one is * running, let it run out). */ return; do_gettimeofday(&now); if (now.tv_usec >= USEC_AFTER - ((unsigned) TICK_SIZE) / 2 && now.tv_usec <= USEC_BEFORE + ((unsigned) TICK_SIZE) / 2) fail = set_rtc_mmss(now.tv_sec); next.tv_usec = USEC_AFTER - now.tv_usec; if (next.tv_usec <= 0) next.tv_usec += USEC_PER_SEC; if (!fail) next.tv_sec = 659; else next.tv_sec = 0; if (next.tv_usec >= USEC_PER_SEC) { next.tv_sec++; next.tv_usec -= USEC_PER_SEC; } mod_timer(&sync_cmos_timer, jiffies + timeval_to_jiffies(&next)); } void notify_arch_cmos_timer(void) { mod_timer(&sync_cmos_timer, jiffies + 1); } static long clock_cmos_diff, sleep_start; static struct timer_opts *last_timer; static int timer_suspend(struct sys_device *dev, pm_message_t state) { /* * Estimate time zone so that set_time can update the clock */ clock_cmos_diff = -get_cmos_time(); clock_cmos_diff += get_seconds(); sleep_start = get_cmos_time(); last_timer = cur_timer; cur_timer = &timer_none; if (last_timer->suspend) last_timer->suspend(state); return 0; } static int timer_resume(struct sys_device *dev) { unsigned long flags; unsigned long sec; unsigned long sleep_length; #ifdef CONFIG_HPET_TIMER if (is_hpet_enabled()) hpet_reenable(); #endif setup_pit_timer(); sec = get_cmos_time() + clock_cmos_diff; sleep_length = (get_cmos_time() - sleep_start) * HZ; write_seqlock_irqsave(&xtime_lock, flags); xtime.tv_sec = sec; xtime.tv_nsec = 0; write_sequnlock_irqrestore(&xtime_lock, flags); jiffies += sleep_length; wall_jiffies += sleep_length; if (last_timer->resume) last_timer->resume(); cur_timer = last_timer; last_timer = NULL; touch_softlockup_watchdog(); return 0; } static struct sysdev_class timer_sysclass = { .resume = timer_resume, .suspend = timer_suspend, set_kset_name("timer"), }; /* XXX this driverfs 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); #ifdef CONFIG_HPET_TIMER extern void (*late_time_init)(void); /* Duplicate of time_init() below, with hpet_enable part added */ static void __init hpet_time_init(void) { xtime.tv_sec = get_cmos_time(); xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ); set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec); if ((hpet_enable() >= 0) && hpet_use_timer) { printk("Using HPET for base-timer\n"); } cur_timer = select_timer(); printk(KERN_INFO "Using %s for high-res timesource\n",cur_timer->name); time_init_hook(); } #endif void __init time_init(void) { #ifdef CONFIG_HPET_TIMER if (is_hpet_capable()) { /* * HPET initialization needs to do memory-mapped io. So, let * us do a late initialization after mem_init(). */ late_time_init = hpet_time_init; return; } #endif xtime.tv_sec = get_cmos_time(); xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ); set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec); cur_timer = select_timer(); printk(KERN_INFO "Using %s for high-res timesource\n",cur_timer->name); time_init_hook(); }