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/*
* 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/export.h>
#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <asm/cpu-features.h>
#include <asm/cpu-type.h>
#include <asm/div64.h>
#include <asm/time.h>
#ifdef CONFIG_CPU_FREQ
static DEFINE_PER_CPU(unsigned long, pcp_lpj_ref);
static DEFINE_PER_CPU(unsigned long, pcp_lpj_ref_freq);
static unsigned long glb_lpj_ref;
static unsigned long glb_lpj_ref_freq;
static int cpufreq_callback(struct notifier_block *nb,
unsigned long val, void *data)
{
int cpu;
struct cpufreq_freqs *freq = data;
/*
* Skip lpj numbers adjustment if the CPU-freq transition is safe for
* the loops delay. (Is this possible?)
*/
if (freq->flags & CPUFREQ_CONST_LOOPS)
return NOTIFY_OK;
/* Save the initial values of the lpjes for future scaling. */
if (!glb_lpj_ref) {
glb_lpj_ref = boot_cpu_data.udelay_val;
glb_lpj_ref_freq = freq->old;
for_each_online_cpu(cpu) {
per_cpu(pcp_lpj_ref, cpu) =
cpu_data[cpu].udelay_val;
per_cpu(pcp_lpj_ref_freq, cpu) = freq->old;
}
}
cpu = freq->cpu;
/*
* Adjust global lpj variable and per-CPU udelay_val number in
* accordance with the new CPU frequency.
*/
if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) ||
(val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
loops_per_jiffy = cpufreq_scale(glb_lpj_ref,
glb_lpj_ref_freq,
freq->new);
cpu_data[cpu].udelay_val = cpufreq_scale(per_cpu(pcp_lpj_ref, cpu),
per_cpu(pcp_lpj_ref_freq, cpu), freq->new);
}
return NOTIFY_OK;
}
static struct notifier_block cpufreq_notifier = {
.notifier_call = cpufreq_callback,
};
static int __init register_cpufreq_notifier(void)
{
return cpufreq_register_notifier(&cpufreq_notifier,
CPUFREQ_TRANSITION_NOTIFIER);
}
core_initcall(register_cpufreq_notifier);
#endif /* CONFIG_CPU_FREQ */
/*
* forward reference
*/
DEFINE_SPINLOCK(rtc_lock);
EXPORT_SYMBOL(rtc_lock);
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;
EXPORT_SYMBOL_GPL(mips_hpt_frequency);
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. This seems the last version
* produced.
*/
return 1;
}
return 0;
}
void __init time_init(void)
{
plat_time_init();
/*
* The use of the R4k timer as a clock event takes precedence;
* if reading the Count register might interfere with the timer
* interrupt, then we don't use the timer as a clock source.
* We may still use the timer as a clock source though if the
* timer interrupt isn't reliable; the interference doesn't
* matter then, because we don't use the interrupt.
*/
if (mips_clockevent_init() != 0 || !cpu_has_mfc0_count_bug())
init_mips_clocksource();
}
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