/* * 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 #include "mach_time.h" #include #include #include #include "io_ports.h" #include #include "do_timer.h" unsigned int cpu_khz; /* Detected as we calibrate the TSC */ EXPORT_SYMBOL(cpu_khz); DEFINE_SPINLOCK(rtc_lock); EXPORT_SYMBOL(rtc_lock); /* * 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); static int set_rtc_mmss(unsigned long nowtime) { int retval; unsigned long flags; /* gets recalled with irq locally disabled */ /* XXX - does irqsave resolve this? -johnstul */ spin_lock_irqsave(&rtc_lock, flags); retval = set_wallclock(nowtime); spin_unlock_irqrestore(&rtc_lock, flags); return retval; } int timer_ack; unsigned long profile_pc(struct pt_regs *regs) { unsigned long pc = instruction_pointer(regs); #ifdef CONFIG_SMP if (!v8086_mode(regs) && SEGMENT_IS_KERNEL_CODE(regs->xcs) && in_lock_functions(pc)) { #ifdef CONFIG_FRAME_POINTER return *(unsigned long *)(regs->ebp + 4); #else unsigned long *sp = (unsigned long *)®s->esp; /* Return address is either directly at stack pointer or above a saved eflags. Eflags has bits 22-31 zero, kernel addresses don't. */ if (sp[0] >> 22) return sp[0]; if (sp[1] >> 22) return sp[1]; #endif } #endif return pc; } EXPORT_SYMBOL(profile_pc); /* * 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) { #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(); 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. */ u8 irq_v = inb_p( 0x61 ); /* read the current state */ outb_p( irq_v|0x80, 0x61 ); /* reset the IRQ */ } return IRQ_HANDLED; } /* not static: needed by APM */ unsigned long read_persistent_clock(void) { unsigned long retval; unsigned long flags; spin_lock_irqsave(&rtc_lock, flags); retval = get_wallclock(); spin_unlock_irqrestore(&rtc_lock, flags); return retval; } static void sync_cmos_clock(unsigned long dummy); static DEFINE_TIMER(sync_cmos_timer, sync_cmos_clock, 0, 0); int no_sync_cmos_clock; 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) { if (!no_sync_cmos_clock) mod_timer(&sync_cmos_timer, jiffies + 1); } extern void (*late_time_init)(void); /* Duplicate of time_init() below, with hpet_enable part added */ void __init hpet_time_init(void) { if (!hpet_enable()) setup_pit_timer(); time_init_hook(); } /* * This is called directly from init code; we must delay timer setup in the * HPET case as we can't make the decision to turn on HPET this early in the * boot process. * * The chosen time_init function will usually be hpet_time_init, above, but * in the case of virtual hardware, an alternative function may be substituted. */ void __init time_init(void) { tsc_init(); late_time_init = choose_time_init(); }