arch/cris/kernel/time.c

   1 /* $Id: time.c,v 1.14 2004/06/01 05:38:11 starvik Exp $
   2  *
   3  *  linux/arch/cris/kernel/time.c
   4  *
   5  *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
   6  *  Copyright (C) 1999, 2000, 2001 Axis Communications AB
   7  *
   8  * 1994-07-02    Alan Modra
   9  *      fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
  10  * 1995-03-26    Markus Kuhn
  11  *      fixed 500 ms bug at call to set_rtc_mmss, fixed DS12887
  12  *      precision CMOS clock update
  13  * 1996-05-03    Ingo Molnar
  14  *      fixed time warps in do_[slow|fast]_gettimeoffset()
  15  * 1997-09-10   Updated NTP code according to technical memorandum Jan '96
  16  *              "A Kernel Model for Precision Timekeeping" by Dave Mills
  17  *
  18  * Linux/CRIS specific code:
  19  *
  20  * Authors:    Bjorn Wesen
  21  *             Johan Adolfsson
  22  *
  23  */
  24
  25 #include <asm/rtc.h>
  26 #include <linux/errno.h>
  27 #include <linux/module.h>
  28 #include <linux/param.h>
  29 #include <linux/jiffies.h>
  30 #include <linux/bcd.h>
  31 #include <linux/timex.h>
  32 #include <linux/init.h>
  33
  34 u64 jiffies_64 = INITIAL_JIFFIES;
  35
  36 EXPORT_SYMBOL(jiffies_64);
  37
  38 int have_rtc;  /* used to remember if we have an RTC or not */;
  39
  40 #define TICK_SIZE tick
  41
  42 extern unsigned long wall_jiffies;
  43 extern unsigned long loops_per_jiffy; /* init/main.c */
  44 unsigned long loops_per_usec;
  45
  46 extern unsigned long do_slow_gettimeoffset(void);
  47 static unsigned long (*do_gettimeoffset)(void) = do_slow_gettimeoffset;
  48
  49 /*
  50  * This version of gettimeofday has near microsecond resolution.
  51  *
  52  * Note: Division is quite slow on CRIS and do_gettimeofday is called
  53  *       rather often. Maybe we should do some kind of approximation here
  54  *       (a naive approximation would be to divide by 1024).
  55  */
  56 void do_gettimeofday(struct timeval *tv)
  57 {
  58         unsigned long flags;
  59         signed long usec, sec;
  60         local_irq_save(flags);
  61         local_irq_disable();
  62         usec = do_gettimeoffset();
  63         {
  64                 unsigned long lost = jiffies - wall_jiffies;
  65                 if (lost)
  66                         usec += lost * (1000000 / HZ);
  67         }
  68
  69         /*
  70          * If time_adjust is negative then NTP is slowing the clock
  71          * so make sure not to go into next possible interval.
  72          * Better to lose some accuracy than have time go backwards..
  73          */
  74         if (unlikely(time_adjust < 0) && usec > tickadj)
  75                 usec = tickadj;
  76
  77         sec = xtime.tv_sec;
  78         usec += xtime.tv_nsec / 1000;
  79         local_irq_restore(flags);
  80
  81         while (usec >= 1000000) {
  82                 usec -= 1000000;
  83                 sec++;
  84         }
  85
  86         tv->tv_sec = sec;
  87         tv->tv_usec = usec;
  88 }
  89
  90 EXPORT_SYMBOL(do_gettimeofday);
  91
  92 int do_settimeofday(struct timespec *tv)
  93 {
  94         time_t wtm_sec, sec = tv->tv_sec;
  95         long wtm_nsec, nsec = tv->tv_nsec;
  96
  97         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
  98                 return -EINVAL;
  99
 100         write_seqlock_irq(&xtime_lock);
 101         /*
 102          * This is revolting. We need to set "xtime" correctly. However, the
 103          * value in this location is the value at the most recent update of
 104          * wall time.  Discover what correction gettimeofday() would have
 105          * made, and then undo it!
 106          */
 107         nsec -= do_gettimeoffset() * NSEC_PER_USEC;
 108         nsec -= (jiffies - wall_jiffies) * TICK_NSEC;
 109
 110         wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 111         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 112
 113         set_normalized_timespec(&xtime, sec, nsec);
 114         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 115
 116         time_adjust = 0;                /* stop active adjtime() */
 117         time_status |= STA_UNSYNC;
 118         time_maxerror = NTP_PHASE_LIMIT;
 119         time_esterror = NTP_PHASE_LIMIT;
 120         write_sequnlock_irq(&xtime_lock);
 121         clock_was_set();
 122         return 0;
 123 }
 124
 125 EXPORT_SYMBOL(do_settimeofday);
 126
 127
 128 /*
 129  * BUG: This routine does not handle hour overflow properly; it just
 130  *      sets the minutes. Usually you'll only notice that after reboot!
 131  */
 132
 133 int set_rtc_mmss(unsigned long nowtime)
 134 {
 135         int retval = 0;
 136         int real_seconds, real_minutes, cmos_minutes;
 137
 138         printk(KERN_DEBUG "set_rtc_mmss(%lu)\n", nowtime);
 139
 140         if(!have_rtc)
 141                 return 0;
 142
 143         cmos_minutes = CMOS_READ(RTC_MINUTES);
 144         BCD_TO_BIN(cmos_minutes);
 145
 146         /*
 147          * since we're only adjusting minutes and seconds,
 148          * don't interfere with hour overflow. This avoids
 149          * messing with unknown time zones but requires your
 150          * RTC not to be off by more than 15 minutes
 151          */
 152         real_seconds = nowtime % 60;
 153         real_minutes = nowtime / 60;
 154         if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
 155                 real_minutes += 30;             /* correct for half hour time zone */
 156         real_minutes %= 60;
 157
 158         if (abs(real_minutes - cmos_minutes) < 30) {
 159                 BIN_TO_BCD(real_seconds);
 160                 BIN_TO_BCD(real_minutes);
 161                 CMOS_WRITE(real_seconds,RTC_SECONDS);
 162                 CMOS_WRITE(real_minutes,RTC_MINUTES);
 163         } else {
 164                 printk(KERN_WARNING
 165                        "set_rtc_mmss: can't update from %d to %d\n",
 166                        cmos_minutes, real_minutes);
 167                 retval = -1;
 168         }
 169
 170         return retval;
 171 }
 172
 173 /* grab the time from the RTC chip */
 174
 175 unsigned long
 176 get_cmos_time(void)
 177 {
 178         unsigned int year, mon, day, hour, min, sec;
 179
 180         sec = CMOS_READ(RTC_SECONDS);
 181         min = CMOS_READ(RTC_MINUTES);
 182         hour = CMOS_READ(RTC_HOURS);
 183         day = CMOS_READ(RTC_DAY_OF_MONTH);
 184         mon = CMOS_READ(RTC_MONTH);
 185         year = CMOS_READ(RTC_YEAR);
 186
 187         printk(KERN_DEBUG
 188                "rtc: sec 0x%x min 0x%x hour 0x%x day 0x%x mon 0x%x year 0x%x\n",
 189                sec, min, hour, day, mon, year);
 190
 191         BCD_TO_BIN(sec);
 192         BCD_TO_BIN(min);
 193         BCD_TO_BIN(hour);
 194         BCD_TO_BIN(day);
 195         BCD_TO_BIN(mon);
 196         BCD_TO_BIN(year);
 197
 198         if ((year += 1900) < 1970)
 199                 year += 100;
 200
 201         return mktime(year, mon, day, hour, min, sec);
 202 }
 203
 204 /* update xtime from the CMOS settings. used when /dev/rtc gets a SET_TIME.
 205  * TODO: this doesn't reset the fancy NTP phase stuff as do_settimeofday does.
 206  */
 207
 208 void
 209 update_xtime_from_cmos(void)
 210 {
 211         if(have_rtc) {
 212                 xtime.tv_sec = get_cmos_time();
 213                 xtime.tv_nsec = 0;
 214         }
 215 }
 216
 217 /*
 218  * Scheduler clock - returns current time in nanosec units.
 219  */
 220 unsigned long long sched_clock(void)
 221 {
 222         return (unsigned long long)jiffies * (1000000000 / HZ);
 223 }
 224
 225 static int
 226 __init init_udelay(void)
 227 {
 228         loops_per_usec = (loops_per_jiffy * HZ) / 1000000;
 229         return 0;
 230 }
 231
 232 __initcall(init_udelay);