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  */
  34 DEFINE_SPINLOCK(rtc_lock);
  35 EXPORT_SYMBOL(rtc_lock);
  36
  37 int __weak rtc_mips_set_time(unsigned long sec)
  38 {
  39         return 0;
  40 }
  41
  42 int __weak rtc_mips_set_mmss(unsigned long nowtime)
  43 {
  44         return rtc_mips_set_time(nowtime);
  45 }
  46
  47 int update_persistent_clock(struct timespec now)
  48 {
  49         return rtc_mips_set_mmss(now.tv_sec);
  50 }
  51
  52 int null_perf_irq(void)
  53 {
  54         return 0;
  55 }
  56
  57 EXPORT_SYMBOL(null_perf_irq);
  58
  59 int (*perf_irq)(void) = null_perf_irq;
  60
  61 EXPORT_SYMBOL(perf_irq);
  62
  63 /*
  64  * time_init() - it does the following things.
  65  *
  66  * 1) plat_time_init() -
  67  *      a) (optional) set up RTC routines,
  68  *      b) (optional) calibrate and set the mips_hpt_frequency
  69  *          (only needed if you intended to use cpu counter as timer interrupt
  70  *           source)
  71  * 2) calculate a couple of cached variables for later usage
  72  */
  73
  74 unsigned int mips_hpt_frequency;
  75
  76 void __init clocksource_set_clock(struct clocksource *cs, unsigned int clock)
  77 {
  78         u64 temp;
  79         u32 shift;
  80
  81         /* Find a shift value */
  82         for (shift = 32; shift > 0; shift--) {
  83                 temp = (u64) NSEC_PER_SEC << shift;
  84                 do_div(temp, clock);
  85                 if ((temp >> 32) == 0)
  86                         break;
  87         }
  88         cs->shift = shift;
  89         cs->mult = (u32) temp;
  90 }
  91
  92 void __cpuinit clockevent_set_clock(struct clock_event_device *cd,
  93         unsigned int clock)
  94 {
  95         u64 temp;
  96         u32 shift;
  97
  98         /* Find a shift value */
  99         for (shift = 32; shift > 0; shift--) {
 100                 temp = (u64) clock << shift;
 101                 do_div(temp, NSEC_PER_SEC);
 102                 if ((temp >> 32) == 0)
 103                         break;
 104         }
 105         cd->shift = shift;
 106         cd->mult = (u32) temp;
 107 }
 108
 109 /*
 110  * This function exists in order to cause an error due to a duplicate
 111  * definition if platform code should have its own implementation.  The hook
 112  * to use instead is plat_time_init.  plat_time_init does not receive the
 113  * irqaction pointer argument anymore.  This is because any function which
 114  * initializes an interrupt timer now takes care of its own request_irq rsp.
 115  * setup_irq calls and each clock_event_device should use its own
 116  * struct irqrequest.
 117  */
 118 void __init plat_timer_setup(void)
 119 {
 120         BUG();
 121 }
 122
 123 static __init int cpu_has_mfc0_count_bug(void)
 124 {
 125         switch (current_cpu_type()) {
 126         case CPU_R4000PC:
 127         case CPU_R4000SC:
 128         case CPU_R4000MC:
 129                 /*
 130                  * V3.0 is documented as suffering from the mfc0 from count bug.
 131                  * Afaik this is the last version of the R4000.  Later versions
 132                  * were marketed as R4400.
 133                  */
 134                 return 1;
 135
 136         case CPU_R4400PC:
 137         case CPU_R4400SC:
 138         case CPU_R4400MC:
 139                 /*
 140                  * The published errata for the R4400 upto 3.0 say the CPU
 141                  * has the mfc0 from count bug.
 142                  */
 143                 if ((current_cpu_data.processor_id & 0xff) <= 0x30)
 144                         return 1;
 145
 146                 /*
 147                  * we assume newer revisions are ok
 148                  */
 149                 return 0;
 150         }
 151
 152         return 0;
 153 }
 154
 155 void __init time_init(void)
 156 {
 157         plat_time_init();
 158
 159         if (!mips_clockevent_init() || !cpu_has_mfc0_count_bug())
 160                 init_mips_clocksource();
 161 }