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 EXPORT_SYMBOL(rtc_mips_set_time);
  42
  43 int __weak rtc_mips_set_mmss(unsigned long nowtime)
  44 {
  45         return rtc_mips_set_time(nowtime);
  46 }
  47
  48 int update_persistent_clock(struct timespec now)
  49 {
  50         return rtc_mips_set_mmss(now.tv_sec);
  51 }
  52
  53 int null_perf_irq(void)
  54 {
  55         return 0;
  56 }
  57
  58 EXPORT_SYMBOL(null_perf_irq);
  59
  60 int (*perf_irq)(void) = null_perf_irq;
  61
  62 EXPORT_SYMBOL(perf_irq);
  63
  64 /*
  65  * time_init() - it does the following things.
  66  *
  67  * 1) plat_time_init() -
  68  *      a) (optional) set up RTC routines,
  69  *      b) (optional) calibrate and set the mips_hpt_frequency
  70  *          (only needed if you intended to use cpu counter as timer interrupt
  71  *           source)
  72  * 2) calculate a couple of cached variables for later usage
  73  */
  74
  75 unsigned int mips_hpt_frequency;
  76
  77 void __init clocksource_set_clock(struct clocksource *cs, unsigned int clock)
  78 {
  79         u64 temp;
  80         u32 shift;
  81
  82         /* Find a shift value */
  83         for (shift = 32; shift > 0; shift--) {
  84                 temp = (u64) NSEC_PER_SEC << shift;
  85                 do_div(temp, clock);
  86                 if ((temp >> 32) == 0)
  87                         break;
  88         }
  89         cs->shift = shift;
  90         cs->mult = (u32) temp;
  91 }
  92
  93 void __cpuinit clockevent_set_clock(struct clock_event_device *cd,
  94         unsigned int clock)
  95 {
  96         u64 temp;
  97         u32 shift;
  98
  99         /* Find a shift value */
 100         for (shift = 32; shift > 0; shift--) {
 101                 temp = (u64) clock << shift;
 102                 do_div(temp, NSEC_PER_SEC);
 103                 if ((temp >> 32) == 0)
 104                         break;
 105         }
 106         cd->shift = shift;
 107         cd->mult = (u32) temp;
 108 }
 109
 110 /*
 111  * This function exists in order to cause an error due to a duplicate
 112  * definition if platform code should have its own implementation.  The hook
 113  * to use instead is plat_time_init.  plat_time_init does not receive the
 114  * irqaction pointer argument anymore.  This is because any function which
 115  * initializes an interrupt timer now takes care of its own request_irq rsp.
 116  * setup_irq calls and each clock_event_device should use its own
 117  * struct irqrequest.
 118  */
 119 void __init plat_timer_setup(void)
 120 {
 121         BUG();
 122 }
 123
 124 static __init int cpu_has_mfc0_count_bug(void)
 125 {
 126         switch (current_cpu_type()) {
 127         case CPU_R4000PC:
 128         case CPU_R4000SC:
 129         case CPU_R4000MC:
 130                 /*
 131                  * V3.0 is documented as suffering from the mfc0 from count bug.
 132                  * Afaik this is the last version of the R4000.  Later versions
 133                  * were marketed as R4400.
 134                  */
 135                 return 1;
 136
 137         case CPU_R4400PC:
 138         case CPU_R4400SC:
 139         case CPU_R4400MC:
 140                 /*
 141                  * The published errata for the R4400 upto 3.0 say the CPU
 142                  * has the mfc0 from count bug.
 143                  */
 144                 if ((current_cpu_data.processor_id & 0xff) <= 0x30)
 145                         return 1;
 146
 147                 /*
 148                  * we assume newer revisions are ok
 149                  */
 150                 return 0;
 151         }
 152
 153         return 0;
 154 }
 155
 156 void __init time_init(void)
 157 {
 158         plat_time_init();
 159
 160         if (!mips_clockevent_init() || !cpu_has_mfc0_count_bug())
 161                 init_mips_clocksource();
 162 }