arch/arm26/kernel/time.c

   1 /*
   2  *  linux/arch/arm26/kernel/time.c
   3  *
   4  *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
   5  *  Modifications for ARM (C) 1994-2001 Russell King
   6  *  Mods for ARM26 (C) 2003 Ian Molton
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  *  This file contains the ARM-specific time handling details:
  13  *  reading the RTC at bootup, etc...
  14  *
  15  *  1994-07-02  Alan Modra
  16  *              fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
  17  *  1998-12-20  Updated NTP code according to technical memorandum Jan '96
  18  *              "A Kernel Model for Precision Timekeeping" by Dave Mills
  19  */
  20
  21 #include <linux/config.h>
  22 #include <linux/module.h>
  23 #include <linux/kernel.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/time.h>
  26 #include <linux/init.h>
  27 #include <linux/smp.h>
  28 #include <linux/timex.h>
  29 #include <linux/errno.h>
  30 #include <linux/profile.h>
  31
  32 #include <asm/hardware.h>
  33 #include <asm/io.h>
  34 #include <asm/irq.h>
  35 #include <asm/leds.h>
  36
  37 u64 jiffies_64 = INITIAL_JIFFIES;
  38
  39 EXPORT_SYMBOL(jiffies_64);
  40
  41 extern unsigned long wall_jiffies;
  42
  43 /* this needs a better home */
  44 spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED;
  45
  46 /* change this if you have some constant time drift */
  47 #define USECS_PER_JIFFY (1000000/HZ)
  48
  49 static int dummy_set_rtc(void)
  50 {
  51         return 0;
  52 }
  53
  54 /*
  55  * hook for setting the RTC's idea of the current time.
  56  */
  57 int (*set_rtc)(void) = dummy_set_rtc;
  58
  59 static unsigned long dummy_gettimeoffset(void)
  60 {
  61         return 0;
  62 }
  63
  64 /*
  65  * hook for getting the time offset.  Note that it is
  66  * always called with interrupts disabled.
  67  */
  68 unsigned long (*gettimeoffset)(void) = dummy_gettimeoffset;
  69
  70 static unsigned long next_rtc_update;
  71
  72 /*
  73  * If we have an externally synchronized linux clock, then update
  74  * CMOS clock accordingly every ~11 minutes.  set_rtc() has to be
  75  * called as close as possible to 500 ms before the new second
  76  * starts.
  77  */
  78 static inline void do_set_rtc(void)
  79 {
  80         if (time_status & STA_UNSYNC || set_rtc == NULL)
  81                 return;
  82
  83 //FIXME - timespec.tv_sec is a time_t not unsigned long
  84         if (next_rtc_update &&
  85             time_before((unsigned long)xtime.tv_sec, next_rtc_update))
  86                 return;
  87
  88         if (xtime.tv_nsec < 500000000 - ((unsigned) tick_nsec >> 1) &&
  89             xtime.tv_nsec >= 500000000 + ((unsigned) tick_nsec >> 1))
  90                 return;
  91
  92         if (set_rtc())
  93                 /*
  94                  * rtc update failed.  Try again in 60s
  95                  */
  96                 next_rtc_update = xtime.tv_sec + 60;
  97         else
  98                 next_rtc_update = xtime.tv_sec + 660;
  99 }
 100
 101 #define do_leds()
 102
 103 void do_gettimeofday(struct timeval *tv)
 104 {
 105         unsigned long flags;
 106         unsigned long seq;
 107         unsigned long usec, sec, lost;
 108
 109         do {
 110                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 111                 usec = gettimeoffset();
 112
 113                 lost = jiffies - wall_jiffies;
 114                 if (lost)
 115                         usec += lost * USECS_PER_JIFFY;
 116
 117                 sec = xtime.tv_sec;
 118                 usec += xtime.tv_nsec / 1000;
 119         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 120
 121         /* usec may have gone up a lot: be safe */
 122         while (usec >= 1000000) {
 123                 usec -= 1000000;
 124                 sec++;
 125         }
 126
 127         tv->tv_sec = sec;
 128         tv->tv_usec = usec;
 129 }
 130
 131 EXPORT_SYMBOL(do_gettimeofday);
 132
 133 int do_settimeofday(struct timespec *tv)
 134 {
 135         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 136                 return -EINVAL;
 137
 138         write_seqlock_irq(&xtime_lock);
 139         /*
 140          * This is revolting. We need to set "xtime" correctly. However, the
 141          * value in this location is the value at the most recent update of
 142          * wall time.  Discover what correction gettimeofday() would have
 143          * done, and then undo it!
 144          */
 145         tv->tv_nsec -= 1000 * (gettimeoffset() +
 146                         (jiffies - wall_jiffies) * USECS_PER_JIFFY);
 147
 148         while (tv->tv_nsec < 0) {
 149                 tv->tv_nsec += NSEC_PER_SEC;
 150                 tv->tv_sec--;
 151         }
 152
 153         xtime.tv_sec = tv->tv_sec;
 154         xtime.tv_nsec = tv->tv_nsec;
 155         time_adjust = 0;                /* stop active adjtime() */
 156         time_status |= STA_UNSYNC;
 157         time_maxerror = NTP_PHASE_LIMIT;
 158         time_esterror = NTP_PHASE_LIMIT;
 159         write_sequnlock_irq(&xtime_lock);
 160         clock_was_set();
 161         return 0;
 162 }
 163
 164 EXPORT_SYMBOL(do_settimeofday);
 165
 166 static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 167 {
 168         do_timer(regs);
 169         do_set_rtc(); //FIME - EVERY timer IRQ?
 170         profile_tick(CPU_PROFILING, regs);
 171         return IRQ_HANDLED; //FIXME - is this right?
 172 }
 173
 174 static struct irqaction timer_irq = {
 175         .name   = "timer",
 176         .flags  = SA_INTERRUPT,
 177         .handler = timer_interrupt,
 178 };
 179
 180 extern void ioctime_init(void);
 181
 182 /*
 183  * Set up timer interrupt.
 184  */
 185 void __init time_init(void)
 186 {
 187         ioctime_init();
 188
 189         setup_irq(IRQ_TIMER, &timer_irq);
 190 }
 191