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 *  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 <cananian@alumni.princeton.edu>, Andrew D.
 *    Balsa <andrebalsa@altern.org>, Philip Gladstone <philip@raptor.com>;
 *    ported from 2.0.35 Jumbo-9 by Michael Krause <m.krause@tu-harburg.de>).
 * 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 <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/module.h>
#include <linux/sysdev.h>
#include <linux/bcd.h>
#include <linux/efi.h>
#include <linux/mca.h>

#include <asm/io.h>
#include <asm/smp.h>
#include <asm/irq.h>
#include <asm/msr.h>
#include <asm/delay.h>
#include <asm/mpspec.h>
#include <asm/uaccess.h>
#include <asm/processor.h>
#include <asm/timer.h>
#include <asm/time.h>

#include "mach_time.h"

#include <linux/timex.h>

#include <asm/hpet.h>

#include <asm/arch_hooks.h>

#include "io_ports.h"

#include <asm/i8259.h>

#include "do_timer.h"

unsigned int cpu_khz;   /* Detected as we calibrate the TSC */


 * 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;

/* Routines for accessing the CMOS RAM/RTC. */
unsigned char rtc_cmos_read(unsigned char addr)
      unsigned char val;
      outb_p(addr, RTC_PORT(0));
      val = inb_p(RTC_PORT(1));
      return val;

void rtc_cmos_write(unsigned char val, unsigned char addr)
      outb_p(addr, RTC_PORT(0));
      outb_p(val, RTC_PORT(1));

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);

      if (!v8086_mode(regs) && SEGMENT_IS_KERNEL_CODE(regs->xcs) &&
          in_lock_functions(pc)) {
            return *(unsigned long *)(regs->ebp + 4);
            unsigned long *sp = (unsigned long *)&regs->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];
      return 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)
      /* Keep nmi watchdog up to date */
      per_cpu(irq_stat, smp_processor_id()).irq0_irqs++;

      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.
            outb(0x0c, PIC_MASTER_OCW3);
            /* Ack the IRQ; AEOI will end it automatically. */


      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;

int update_persistent_clock(struct timespec now)
      return set_rtc_mmss(now.tv_sec);

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())

 * 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)
      late_time_init = choose_time_init();

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