122 строки
2.8 KiB
C
122 строки
2.8 KiB
C
/*
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* Copyright 2001 MontaVista Software Inc.
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* Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
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* Copyright (c) 2003, 2004 Maciej W. Rozycki
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*
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* Common time service routines for MIPS machines.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*/
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#include <linux/bug.h>
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#include <linux/clockchips.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/param.h>
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#include <linux/time.h>
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#include <linux/timex.h>
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#include <linux/smp.h>
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#include <linux/spinlock.h>
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#include <linux/export.h>
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#include <asm/cpu-features.h>
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#include <asm/cpu-type.h>
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#include <asm/div64.h>
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#include <asm/time.h>
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/*
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* forward reference
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*/
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DEFINE_SPINLOCK(rtc_lock);
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EXPORT_SYMBOL(rtc_lock);
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int __weak rtc_mips_set_time(unsigned long sec)
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{
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return -ENODEV;
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}
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int __weak rtc_mips_set_mmss(unsigned long nowtime)
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{
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return rtc_mips_set_time(nowtime);
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}
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int update_persistent_clock(struct timespec now)
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{
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return rtc_mips_set_mmss(now.tv_sec);
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}
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static int null_perf_irq(void)
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{
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return 0;
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}
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int (*perf_irq)(void) = null_perf_irq;
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EXPORT_SYMBOL(perf_irq);
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/*
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* time_init() - it does the following things.
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*
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* 1) plat_time_init() -
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* a) (optional) set up RTC routines,
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* b) (optional) calibrate and set the mips_hpt_frequency
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* (only needed if you intended to use cpu counter as timer interrupt
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* source)
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* 2) calculate a couple of cached variables for later usage
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*/
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unsigned int mips_hpt_frequency;
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EXPORT_SYMBOL_GPL(mips_hpt_frequency);
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static __init int cpu_has_mfc0_count_bug(void)
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{
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switch (current_cpu_type()) {
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case CPU_R4000PC:
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case CPU_R4000SC:
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case CPU_R4000MC:
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/*
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* V3.0 is documented as suffering from the mfc0 from count bug.
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* Afaik this is the last version of the R4000. Later versions
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* were marketed as R4400.
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*/
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return 1;
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case CPU_R4400PC:
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case CPU_R4400SC:
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case CPU_R4400MC:
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/*
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* The published errata for the R4400 up to 3.0 say the CPU
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* has the mfc0 from count bug.
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*/
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if ((current_cpu_data.processor_id & 0xff) <= 0x30)
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return 1;
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/*
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* we assume newer revisions are ok
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*/
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return 0;
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}
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return 0;
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}
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void __init time_init(void)
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{
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plat_time_init();
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/*
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* The use of the R4k timer as a clock event takes precedence;
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* if reading the Count register might interfere with the timer
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* interrupt, then we don't use the timer as a clock source.
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* We may still use the timer as a clock source though if the
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* timer interrupt isn't reliable; the interference doesn't
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* matter then, because we don't use the interrupt.
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*/
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if (mips_clockevent_init() != 0 || !cpu_has_mfc0_count_bug())
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init_mips_clocksource();
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}
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