mirror of
https://github.com/torvalds/linux
synced 2024-10-16 08:19:01 +00:00
940f6b48a1
In particular as-is it's not suited for multicore and mutiprocessors systems where there is on guarantee that the counter are synchronized or running from the same clock at all. This broke Sibyte and probably others since the "[MIPS] Handle R4000/R4400 mfc0 from count register." commit. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
169 lines
3.7 KiB
C
169 lines
3.7 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/module.h>
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#include <asm/cpu-features.h>
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#include <asm/div64.h>
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#include <asm/smtc_ipi.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 0;
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}
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EXPORT_SYMBOL(rtc_mips_set_time);
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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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int (*mips_timer_state)(void);
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int null_perf_irq(void)
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{
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return 0;
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}
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EXPORT_SYMBOL(null_perf_irq);
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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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void __init clocksource_set_clock(struct clocksource *cs, unsigned int clock)
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{
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u64 temp;
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u32 shift;
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/* Find a shift value */
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for (shift = 32; shift > 0; shift--) {
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temp = (u64) NSEC_PER_SEC << shift;
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do_div(temp, clock);
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if ((temp >> 32) == 0)
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break;
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}
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cs->shift = shift;
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cs->mult = (u32) temp;
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}
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void __cpuinit clockevent_set_clock(struct clock_event_device *cd,
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unsigned int clock)
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{
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u64 temp;
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u32 shift;
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/* Find a shift value */
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for (shift = 32; shift > 0; shift--) {
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temp = (u64) clock << shift;
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do_div(temp, NSEC_PER_SEC);
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if ((temp >> 32) == 0)
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break;
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}
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cd->shift = shift;
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cd->mult = (u32) temp;
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}
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void __init __weak plat_time_init(void)
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{
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}
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/*
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* This function exists in order to cause an error due to a duplicate
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* definition if platform code should have its own implementation. The hook
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* to use instead is plat_time_init. plat_time_init does not receive the
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* irqaction pointer argument anymore. This is because any function which
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* initializes an interrupt timer now takes care of its own request_irq rsp.
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* setup_irq calls and each clock_event_device should use its own
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* struct irqrequest.
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*/
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void __init plat_timer_setup(void)
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{
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BUG();
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}
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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 upto 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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* I don't have erratas for newer R4400 so be paranoid.
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*/
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return 1;
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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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if (mips_clockevent_init() || !cpu_has_mfc0_count_bug())
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init_mips_clocksource();
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}
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