arch/arm/kernel/time.c

   1 /*
   2  *  linux/arch/arm/kernel/time.c
   3  *
   4  *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
   5  *  Modifications for ARM (C) 1994, 1995, 1996,1997 Russell King
   6  *
   7  * This file contains the ARM-specific time handling details:
   8  * reading the RTC at bootup, etc...
   9  *
  10  * 1994-07-02  Alan Modra
  11  *             fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
  12  * 1998-12-20  Updated NTP code according to technical memorandum Jan '96
  13  *             "A Kernel Model for Precision Timekeeping" by Dave Mills
  14  */
  15 #include <linux/errno.h>
  16 #include <linux/sched.h>
  17 #include <linux/kernel.h>
  18 #include <linux/param.h>
  19 #include <linux/string.h>
  20 #include <linux/mm.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/time.h>
  23 #include <linux/delay.h>
  24 #include <linux/init.h>
  25 #include <linux/smp.h>
  26 #include <linux/init.h>
  27 #include <linux/delay.h>
  28
  29 #include <asm/uaccess.h>
  30 #include <asm/io.h>
  31 #include <asm/irq.h>
  32
  33 #include <linux/timex.h>
  34 #include <asm/hardware.h>
  35
  36 extern int setup_arm_irq(int, struct irqaction *);
  37 extern volatile unsigned long lost_ticks;
  38
  39 /* change this if you have some constant time drift */
  40 #define USECS_PER_JIFFY (1000000/HZ)
  41
  42 #ifndef BCD_TO_BIN
  43 #define BCD_TO_BIN(val) ((val)=((val)&15) + ((val)>>4)*10)
  44 #endif
  45
  46 #ifndef BIN_TO_BCD
  47 #define BIN_TO_BCD(val) ((val)=(((val)/10)<<4) + (val)%10)
  48 #endif
  49
  50 /* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
  51  * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
  52  * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
  53  *
  54  * [For the Julian calendar (which was used in Russia before 1917,
  55  * Britain & colonies before 1752, anywhere else before 1582,
  56  * and is still in use by some communities) leave out the
  57  * -year/100+year/400 terms, and add 10.]
  58  *
  59  * This algorithm was first published by Gauss (I think).
  60  *
  61  * WARNING: this function will overflow on 2106-02-07 06:28:16 on
  62  * machines were long is 32-bit! (However, as time_t is signed, we
  63  * will already get problems at other places on 2038-01-19 03:14:08)
  64  */
  65 unsigned long mktime(unsigned int year, unsigned int mon,
  66         unsigned int day, unsigned int hour,
  67         unsigned int min, unsigned int sec)
  68 {
  69         if (0 >= (int) (mon -= 2)) {    /* 1..12 -> 11,12,1..10 */
  70                 mon += 12;      /* Puts Feb last since it has leap day */
  71                 year -= 1;
  72         }
  73         return (((
  74                     (unsigned long)(year/4 - year/100 + year/400 + 367*mon/12 + day) +
  75                       year*365 - 719499
  76                     )*24 + hour /* now have hours */
  77                    )*60 + min /* now have minutes */
  78                   )*60 + sec; /* finally seconds */
  79 }
  80
  81 #include <asm/arch/time.h>
  82
  83 static unsigned long do_gettimeoffset(void)
  84 {
  85         return gettimeoffset ();
  86 }
  87
  88 void do_gettimeofday(struct timeval *tv)
  89 {
  90         unsigned long flags;
  91
  92         save_flags_cli (flags);
  93         *tv = xtime;
  94         tv->tv_usec += do_gettimeoffset();
  95
  96         /*
  97          * xtime is atomically updated in timer_bh. lost_ticks is
  98          * nonzero if the tiemr bottom half hasnt executed yet.
  99          */
 100         if (lost_ticks)
 101                 tv->tv_usec += USECS_PER_JIFFY;
 102
 103         restore_flags(flags);
 104
 105         if (tv->tv_usec >= 1000000) {
 106                 tv->tv_usec -= 1000000;
 107                 tv->tv_sec++;
 108         }
 109 }
 110
 111 void do_settimeofday(struct timeval *tv)
 112 {
 113         cli ();
 114         /* This is revolting. We need to set the xtime.tv_usec
 115          * correctly. However, the value in this location is
 116          * is value at the last tick.
 117          * Discover what correction gettimeofday
 118          * would have done, and then undo it!
 119          */
 120         tv->tv_usec -= do_gettimeoffset();
 121
 122         if (tv->tv_usec < 0) {
 123                 tv->tv_usec += 1000000;
 124                 tv->tv_sec--;
 125         }
 126
 127         xtime = *tv;
 128         time_adjust = 0;                /* stop active adjtime() */
 129         time_status |= STA_UNSYNC;
 130         time_state = TIME_ERROR;        /* p. 24, (a) */
 131         time_maxerror = NTP_PHASE_LIMIT;
 132         time_esterror = NTP_PHASE_LIMIT;
 133         sti ();
 134 }
 135
 136 /*
 137  * timer_interrupt() needs to keep up the real-time clock,
 138  * as well as call the "do_timer()" routine every clocktick.
 139  */
 140 static void timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 141 {
 142         if (reset_timer ())
 143                 do_timer(regs);
 144
 145         update_rtc ();
 146 }
 147
 148 static struct irqaction irqtimer = { timer_interrupt, 0, 0, "timer", NULL, NULL};
 149
 150 __initfunc(void time_init(void))
 151 {
 152         xtime.tv_sec = setup_timer();
 153         xtime.tv_usec = 0;
 154
 155         setup_arm_irq(IRQ_TIMER, &irqtimer);
 156 }