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time.c

/*
 * Copyright 2001 MontaVista Software Inc.
 * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
 * Copyright (c) 2003, 2004  Maciej W. Rozycki
 *
 * Common time service routines for MIPS machines.
 *
 * This program is free software; you can redistribute  it and/or modify it
 * under  the terms of  the GNU General  Public License as published by the
 * Free Software Foundation;  either version 2 of the  License, or (at your
 * option) any later version.
 */
#include <linux/bug.h>
#include <linux/clockchips.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/param.h>
#include <linux/time.h>
#include <linux/timex.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <linux/module.h>

#include <asm/cpu-features.h>
#include <asm/div64.h>
#include <asm/smtc_ipi.h>
#include <asm/time.h>

/*
 * forward reference
 */
DEFINE_SPINLOCK(rtc_lock);
EXPORT_SYMBOL(rtc_lock);

int __weak rtc_mips_set_time(unsigned long sec)
{
      return 0;
}
EXPORT_SYMBOL(rtc_mips_set_time);

int __weak rtc_mips_set_mmss(unsigned long nowtime)
{
      return rtc_mips_set_time(nowtime);
}

int update_persistent_clock(struct timespec now)
{
      return rtc_mips_set_mmss(now.tv_sec);
}

int (*mips_timer_state)(void);

int null_perf_irq(void)
{
      return 0;
}

EXPORT_SYMBOL(null_perf_irq);

int (*perf_irq)(void) = null_perf_irq;

EXPORT_SYMBOL(perf_irq);

/*
 * time_init() - it does the following things.
 *
 * 1) plat_time_init() -
 *    a) (optional) set up RTC routines,
 *      b) (optional) calibrate and set the mips_hpt_frequency
 *        (only needed if you intended to use cpu counter as timer interrupt
 *         source)
 * 2) calculate a couple of cached variables for later usage
 */

unsigned int mips_hpt_frequency;

void __init clocksource_set_clock(struct clocksource *cs, unsigned int clock)
{
      u64 temp;
      u32 shift;

      /* Find a shift value */
      for (shift = 32; shift > 0; shift--) {
            temp = (u64) NSEC_PER_SEC << shift;
            do_div(temp, clock);
            if ((temp >> 32) == 0)
                  break;
      }
      cs->shift = shift;
      cs->mult = (u32) temp;
}

void __cpuinit clockevent_set_clock(struct clock_event_device *cd,
      unsigned int clock)
{
      u64 temp;
      u32 shift;

      /* Find a shift value */
      for (shift = 32; shift > 0; shift--) {
            temp = (u64) clock << shift;
            do_div(temp, NSEC_PER_SEC);
            if ((temp >> 32) == 0)
                  break;
      }
      cd->shift = shift;
      cd->mult = (u32) temp;
}

/*
 * This function exists in order to cause an error due to a duplicate
 * definition if platform code should have its own implementation.  The hook
 * to use instead is plat_time_init.  plat_time_init does not receive the
 * irqaction pointer argument anymore.  This is because any function which
 * initializes an interrupt timer now takes care of its own request_irq rsp.
 * setup_irq calls and each clock_event_device should use its own
 * struct irqrequest.
 */
void __init plat_timer_setup(void)
{
      BUG();
}

static __init int cpu_has_mfc0_count_bug(void)
{
      switch (current_cpu_type()) {
      case CPU_R4000PC:
      case CPU_R4000SC:
      case CPU_R4000MC:
            /*
             * V3.0 is documented as suffering from the mfc0 from count bug.
             * Afaik this is the last version of the R4000.  Later versions
             * were marketed as R4400.
             */
            return 1;

      case CPU_R4400PC:
      case CPU_R4400SC:
      case CPU_R4400MC:
            /*
             * The published errata for the R4400 upto 3.0 say the CPU
             * has the mfc0 from count bug.
             */
            if ((current_cpu_data.processor_id & 0xff) <= 0x30)
                  return 1;

            /*
             * we assume newer revisions are ok
             */
            return 0;
      }

      return 0;
}

void __init time_init(void)
{
      plat_time_init();

      if (mips_clockevent_init() || !cpu_has_mfc0_count_bug())
            init_mips_clocksource();
}

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