arch/mips/dec/time.c

   1 /*
   2  *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
   3  *  Copyright (C) 2000, 2003  Maciej W. Rozycki
   4  *
   5  * This file contains the time handling details for PC-style clocks as
   6  * found in some MIPS systems.
   7  *
   8  */
   9 #include <linux/bcd.h>
  10 #include <linux/init.h>
  11 #include <linux/mc146818rtc.h>
  12 #include <linux/param.h>
  13
  14 #include <asm/cpu-features.h>
  15 #include <asm/ds1287.h>
  16 #include <asm/time.h>
  17 #include <asm/dec/interrupts.h>
  18 #include <asm/dec/ioasic.h>
  19 #include <asm/dec/machtype.h>
  20
  21 unsigned long read_persistent_clock(void)
  22 {
  23         unsigned int year, mon, day, hour, min, sec, real_year;
  24         unsigned long flags;
  25
  26         spin_lock_irqsave(&rtc_lock, flags);
  27
  28         do {
  29                 sec = CMOS_READ(RTC_SECONDS);
  30                 min = CMOS_READ(RTC_MINUTES);
  31                 hour = CMOS_READ(RTC_HOURS);
  32                 day = CMOS_READ(RTC_DAY_OF_MONTH);
  33                 mon = CMOS_READ(RTC_MONTH);
  34                 year = CMOS_READ(RTC_YEAR);
  35                 /*
  36                  * The PROM will reset the year to either '72 or '73.
  37                  * Therefore we store the real year separately, in one
  38                  * of unused BBU RAM locations.
  39                  */
  40                 real_year = CMOS_READ(RTC_DEC_YEAR);
  41         } while (sec != CMOS_READ(RTC_SECONDS));
  42
  43         spin_unlock_irqrestore(&rtc_lock, flags);
  44
  45         if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
  46                 sec = bcd2bin(sec);
  47                 min = bcd2bin(min);
  48                 hour = bcd2bin(hour);
  49                 day = bcd2bin(day);
  50                 mon = bcd2bin(mon);
  51                 year = bcd2bin(year);
  52         }
  53
  54         year += real_year - 72 + 2000;
  55
  56         return mktime(year, mon, day, hour, min, sec);
  57 }
  58
  59 /*
  60  * In order to set the CMOS clock precisely, rtc_mips_set_mmss has to
  61  * be called 500 ms after the second nowtime has started, because when
  62  * nowtime is written into the registers of the CMOS clock, it will
  63  * jump to the next second precisely 500 ms later.  Check the Dallas
  64  * DS1287 data sheet for details.
  65  */
  66 int rtc_mips_set_mmss(unsigned long nowtime)
  67 {
  68         int retval = 0;
  69         int real_seconds, real_minutes, cmos_minutes;
  70         unsigned char save_control, save_freq_select;
  71
  72         /* irq are locally disabled here */
  73         spin_lock(&rtc_lock);
  74         /* tell the clock it's being set */
  75         save_control = CMOS_READ(RTC_CONTROL);
  76         CMOS_WRITE((save_control | RTC_SET), RTC_CONTROL);
  77
  78         /* stop and reset prescaler */
  79         save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
  80         CMOS_WRITE((save_freq_select | RTC_DIV_RESET2), RTC_FREQ_SELECT);
  81
  82         cmos_minutes = CMOS_READ(RTC_MINUTES);
  83         if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
  84                 cmos_minutes = bcd2bin(cmos_minutes);
  85
  86         /*
  87          * since we're only adjusting minutes and seconds,
  88          * don't interfere with hour overflow. This avoids
  89          * messing with unknown time zones but requires your
  90          * RTC not to be off by more than 15 minutes
  91          */
  92         real_seconds = nowtime % 60;
  93         real_minutes = nowtime / 60;
  94         if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1)
  95                 real_minutes += 30;     /* correct for half hour time zone */
  96         real_minutes %= 60;
  97
  98         if (abs(real_minutes - cmos_minutes) < 30) {
  99                 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
 100                         real_seconds = bin2bcd(real_seconds);
 101                         real_minutes = bin2bcd(real_minutes);
 102                 }
 103                 CMOS_WRITE(real_seconds, RTC_SECONDS);
 104                 CMOS_WRITE(real_minutes, RTC_MINUTES);
 105         } else {
 106                 printk(KERN_WARNING
 107                        "set_rtc_mmss: can't update from %d to %d\n",
 108                        cmos_minutes, real_minutes);
 109                 retval = -1;
 110         }
 111
 112         /* The following flags have to be released exactly in this order,
 113          * otherwise the DS1287 will not reset the oscillator and will not
 114          * update precisely 500 ms later.  You won't find this mentioned
 115          * in the Dallas Semiconductor data sheets, but who believes data
 116          * sheets anyway ...                           -- Markus Kuhn
 117          */
 118         CMOS_WRITE(save_control, RTC_CONTROL);
 119         CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
 120         spin_unlock(&rtc_lock);
 121
 122         return retval;
 123 }
 124
 125 void __init plat_time_init(void)
 126 {
 127         u32 start, end;
 128         int i = HZ / 10;
 129
 130         /* Set up the rate of periodic DS1287 interrupts. */
 131         ds1287_set_base_clock(HZ);
 132
 133         if (cpu_has_counter) {
 134                 while (!ds1287_timer_state())
 135                         ;
 136
 137                 start = read_c0_count();
 138
 139                 while (i--)
 140                         while (!ds1287_timer_state())
 141                                 ;
 142
 143                 end = read_c0_count();
 144
 145                 mips_hpt_frequency = (end - start) * 10;
 146                 printk(KERN_INFO "MIPS counter frequency %dHz\n",
 147                         mips_hpt_frequency);
 148         } else if (IOASIC)
 149                 /* For pre-R4k systems we use the I/O ASIC's counter.  */
 150                 dec_ioasic_clocksource_init();
 151
 152         ds1287_clockevent_init(dec_interrupt[DEC_IRQ_RTC]);
 153 }