LXR linux/arch/mips/kernel/time.c

   1/*
   2 * Copyright 2001 MontaVista Software Inc.
   3 * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
   4 * Copyright (c) 2003, 2004  Maciej W. Rozycki
   5 *
   6 * Common time service routines for MIPS machines.
   7 *
   8 * This program is free software; you can redistribute  it and/or modify it
   9 * under  the terms of  the GNU General  Public License as published by the
  10 * Free Software Foundation;  either version 2 of the  License, or (at your
  11 * option) any later version.
  12 */
  13#include <linux/bug.h>
  14#include <linux/clockchips.h>
  15#include <linux/types.h>
  16#include <linux/kernel.h>
  17#include <linux/init.h>
  18#include <linux/sched.h>
  19#include <linux/param.h>
  20#include <linux/time.h>
  21#include <linux/timex.h>
  22#include <linux/smp.h>
  23#include <linux/spinlock.h>
  24#include <linux/module.h>
  25
  26#include <asm/cpu-features.h>
  27#include <asm/div64.h>
  28#include <asm/smtc_ipi.h>
  29#include <asm/time.h>
  30
  31/*
  32 * forward reference
  33 */
  34DEFINE_SPINLOCK(rtc_lock);
  35EXPORT_SYMBOL(rtc_lock);
  36
  37int __weak rtc_mips_set_time(unsigned long sec)
  38{
  39        return 0;
  40}
  41
  42int __weak rtc_mips_set_mmss(unsigned long nowtime)
  43{
  44        return rtc_mips_set_time(nowtime);
  45}
  46
  47int update_persistent_clock(struct timespec now)
  48{
  49        return rtc_mips_set_mmss(now.tv_sec);
  50}
  51
  52static int null_perf_irq(void)
  53{
  54        return 0;
  55}
  56
  57int (*perf_irq)(void) = null_perf_irq;
  58
  59EXPORT_SYMBOL(perf_irq);
  60
  61/*
  62 * time_init() - it does the following things.
  63 *
  64 * 1) plat_time_init() -
  65 *      a) (optional) set up RTC routines,
  66 *      b) (optional) calibrate and set the mips_hpt_frequency
  67 *          (only needed if you intended to use cpu counter as timer interrupt
  68 *           source)
  69 * 2) calculate a couple of cached variables for later usage
  70 */
  71
  72unsigned int mips_hpt_frequency;
  73
  74void __init clocksource_set_clock(struct clocksource *cs, unsigned int clock)
  75{
  76        u64 temp;
  77        u32 shift;
  78
  79        /* Find a shift value */
  80        for (shift = 32; shift > 0; shift--) {
  81                temp = (u64) NSEC_PER_SEC << shift;
  82                do_div(temp, clock);
  83                if ((temp >> 32) == 0)
  84                        break;
  85        }
  86        cs->shift = shift;
  87        cs->mult = (u32) temp;
  88}
  89
  90void __cpuinit clockevent_set_clock(struct clock_event_device *cd,
  91        unsigned int clock)
  92{
  93        u64 temp;
  94        u32 shift;
  95
  96        /* Find a shift value */
  97        for (shift = 32; shift > 0; shift--) {
  98                temp = (u64) clock << shift;
  99                do_div(temp, NSEC_PER_SEC);
 100                if ((temp >> 32) == 0)
 101                        break;
 102        }
 103        cd->shift = shift;
 104        cd->mult = (u32) temp;
 105}
 106
 107/*
 108 * This function exists in order to cause an error due to a duplicate
 109 * definition if platform code should have its own implementation.  The hook
 110 * to use instead is plat_time_init.  plat_time_init does not receive the
 111 * irqaction pointer argument anymore.  This is because any function which
 112 * initializes an interrupt timer now takes care of its own request_irq rsp.
 113 * setup_irq calls and each clock_event_device should use its own
 114 * struct irqrequest.
 115 */
 116void __init plat_timer_setup(void)
 117{
 118        BUG();
 119}
 120
 121static __init int cpu_has_mfc0_count_bug(void)
 122{
 123        switch (current_cpu_type()) {
 124        case CPU_R4000PC:
 125        case CPU_R4000SC:
 126        case CPU_R4000MC:
 127                /*
 128                 * V3.0 is documented as suffering from the mfc0 from count bug.
 129                 * Afaik this is the last version of the R4000.  Later versions
 130                 * were marketed as R4400.
 131                 */
 132                return 1;
 133
 134        case CPU_R4400PC:
 135        case CPU_R4400SC:
 136        case CPU_R4400MC:
 137                /*
 138                 * The published errata for the R4400 upto 3.0 say the CPU
 139                 * has the mfc0 from count bug.
 140                 */
 141                if ((current_cpu_data.processor_id & 0xff) <= 0x30)
 142                        return 1;
 143
 144                /*
 145                 * we assume newer revisions are ok
 146                 */
 147                return 0;
 148        }
 149
 150        return 0;
 151}
 152
 153void __init time_init(void)
 154{
 155        plat_time_init();
 156
 157        if (!mips_clockevent_init() || !cpu_has_mfc0_count_bug())
 158                init_mips_clocksource();
 159}
 160