140 lines
4.2 KiB
C
140 lines
4.2 KiB
C
/*
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* Copyright (C) 1991, 1992, 1995 Linus Torvalds
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*
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* This file contains the PC-specific time handling details:
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* reading the RTC at bootup, etc..
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* 1994-07-02 Alan Modra
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* fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
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* 1995-03-26 Markus Kuhn
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* fixed 500 ms bug at call to set_rtc_mmss, fixed DS12887
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* precision CMOS clock update
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* 1996-05-03 Ingo Molnar
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* fixed time warps in do_[slow|fast]_gettimeoffset()
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* 1997-09-10 Updated NTP code according to technical memorandum Jan '96
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* "A Kernel Model for Precision Timekeeping" by Dave Mills
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* 1998-09-05 (Various)
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* More robust do_fast_gettimeoffset() algorithm implemented
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* (works with APM, Cyrix 6x86MX and Centaur C6),
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* monotonic gettimeofday() with fast_get_timeoffset(),
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* drift-proof precision TSC calibration on boot
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* (C. Scott Ananian <cananian@alumni.princeton.edu>, Andrew D.
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* Balsa <andrebalsa@altern.org>, Philip Gladstone <philip@raptor.com>;
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* ported from 2.0.35 Jumbo-9 by Michael Krause <m.krause@tu-harburg.de>).
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* 1998-12-16 Andrea Arcangeli
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* Fixed Jumbo-9 code in 2.1.131: do_gettimeofday was missing 1 jiffy
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* because was not accounting lost_ticks.
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* 1998-12-24 Copyright (C) 1998 Andrea Arcangeli
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* Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
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* serialize accesses to xtime/lost_ticks).
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*/
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/time.h>
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#include <linux/mca.h>
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#include <asm/arch_hooks.h>
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#include <asm/hpet.h>
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#include <asm/time.h>
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#include "do_timer.h"
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unsigned int cpu_khz; /* Detected as we calibrate the TSC */
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EXPORT_SYMBOL(cpu_khz);
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int timer_ack;
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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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#ifdef CONFIG_SMP
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if (!v8086_mode(regs) && SEGMENT_IS_KERNEL_CODE(regs->cs) &&
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in_lock_functions(pc)) {
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#ifdef CONFIG_FRAME_POINTER
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return *(unsigned long *)(regs->bp + 4);
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#else
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unsigned long *sp = (unsigned long *)®s->sp;
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/* Return address is either directly at stack pointer
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or above a saved flags. Eflags has bits 22-31 zero,
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kernel addresses don't. */
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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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#endif
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}
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#endif
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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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* This is the same as the above, except we _also_ save the current
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* Time Stamp Counter value at the time of the timer interrupt, so that
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* we later on can estimate the time of day more exactly.
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*/
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irqreturn_t timer_interrupt(int irq, void *dev_id)
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{
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/* Keep nmi watchdog up to date */
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per_cpu(irq_stat, smp_processor_id()).irq0_irqs++;
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#ifdef CONFIG_X86_IO_APIC
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if (timer_ack) {
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/*
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* Subtle, when I/O APICs are used we have to ack timer IRQ
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* manually to reset the IRR bit for do_slow_gettimeoffset().
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* This will also deassert NMI lines for the watchdog if run
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* on an 82489DX-based system.
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*/
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spin_lock(&i8259A_lock);
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outb(0x0c, PIC_MASTER_OCW3);
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/* Ack the IRQ; AEOI will end it automatically. */
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inb(PIC_MASTER_POLL);
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spin_unlock(&i8259A_lock);
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}
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#endif
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do_timer_interrupt_hook();
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if (MCA_bus) {
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/* The PS/2 uses level-triggered interrupts. You can't
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turn them off, nor would you want to (any attempt to
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enable edge-triggered interrupts usually gets intercepted by a
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special hardware circuit). Hence we have to acknowledge
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the timer interrupt. Through some incredibly stupid
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design idea, the reset for IRQ 0 is done by setting the
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high bit of the PPI port B (0x61). Note that some PS/2s,
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notably the 55SX, work fine if this is removed. */
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u8 irq_v = inb_p( 0x61 ); /* read the current state */
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outb_p( irq_v|0x80, 0x61 ); /* reset the IRQ */
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}
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return IRQ_HANDLED;
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}
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extern void (*late_time_init)(void);
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/* Duplicate of time_init() below, with hpet_enable part added */
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void __init hpet_time_init(void)
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{
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if (!hpet_enable())
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setup_pit_timer();
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time_init_hook();
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}
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/*
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* This is called directly from init code; we must delay timer setup in the
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* HPET case as we can't make the decision to turn on HPET this early in the
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* boot process.
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*
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* The chosen time_init function will usually be hpet_time_init, above, but
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* in the case of virtual hardware, an alternative function may be substituted.
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*/
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void __init time_init(void)
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{
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tsc_init();
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late_time_init = choose_time_init();
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}
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