time.c

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/*
 * Copyright 2001 MontaVista Software Inc.
 * Author: Jun Sun, [email protected] or [email protected]
 * 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/export.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;
}

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);
}

static int null_perf_irq(void)
{
    return 0;
}

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;

/*
 * 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 up to 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();
}