arch/mips/dec/time.c

   1 /*
   2  *  linux/arch/mips/dec/time.c
   3  *
   4  *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
   5  *  Copyright (C) 2000, 2003  Maciej W. Rozycki
   6  *
   7  * This file contains the time handling details for PC-style clocks as
   8  * found in some MIPS systems.
   9  *
  10  */
  11 #include <linux/bcd.h>
  12 #include <linux/init.h>
  13 #include <linux/mc146818rtc.h>
  14 #include <linux/param.h>
  15
  16 #include <asm/cpu-features.h>
  17 #include <asm/ds1287.h>
  18 #include <asm/time.h>
  19 #include <asm/dec/interrupts.h>
  20 #include <asm/dec/ioasic.h>
  21 #include <asm/dec/machtype.h>
  22
  23 unsigned long read_persistent_clock(void)
  24 {
  25         unsigned int year, mon, day, hour, min, sec, real_year;
  26         unsigned long flags;
  27
  28         spin_lock_irqsave(&rtc_lock, flags);
  29
  30         do {
  31                 sec = CMOS_READ(RTC_SECONDS);
  32                 min = CMOS_READ(RTC_MINUTES);
  33                 hour = CMOS_READ(RTC_HOURS);
  34                 day = CMOS_READ(RTC_DAY_OF_MONTH);
  35                 mon = CMOS_READ(RTC_MONTH);
  36                 year = CMOS_READ(RTC_YEAR);
  37                 /*
  38                  * The PROM will reset the year to either '72 or '73.
  39                  * Therefore we store the real year separately, in one
  40                  * of unused BBU RAM locations.
  41                  */
  42                 real_year = CMOS_READ(RTC_DEC_YEAR);
  43         } while (sec != CMOS_READ(RTC_SECONDS));
  44
  45         spin_unlock_irqrestore(&rtc_lock, flags);
  46
  47         if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
  48                 sec = bcd2bin(sec);
  49                 min = bcd2bin(min);
  50                 hour = bcd2bin(hour);
  51                 day = bcd2bin(day);
  52                 mon = bcd2bin(mon);
  53                 year = bcd2bin(year);
  54         }
  55
  56         year += real_year - 72 + 2000;
  57
  58         return mktime(year, mon, day, hour, min, sec);
  59 }
  60
  61 /*
  62  * In order to set the CMOS clock precisely, rtc_mips_set_mmss has to
  63  * be called 500 ms after the second nowtime has started, because when
  64  * nowtime is written into the registers of the CMOS clock, it will
  65  * jump to the next second precisely 500 ms later.  Check the Dallas
  66  * DS1287 data sheet for details.
  67  */
  68 int rtc_mips_set_mmss(unsigned long nowtime)
  69 {
  70         int retval = 0;
  71         int real_seconds, real_minutes, cmos_minutes;
  72         unsigned char save_control, save_freq_select;
  73
  74         /* irq are locally disabled here */
  75         spin_lock(&rtc_lock);
  76         /* tell the clock it's being set */
  77         save_control = CMOS_READ(RTC_CONTROL);
  78         CMOS_WRITE((save_control | RTC_SET), RTC_CONTROL);
  79
  80         /* stop and reset prescaler */
  81         save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
  82         CMOS_WRITE((save_freq_select | RTC_DIV_RESET2), RTC_FREQ_SELECT);
  83
  84         cmos_minutes = CMOS_READ(RTC_MINUTES);
  85         if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
  86                 cmos_minutes = bcd2bin(cmos_minutes);
  87
  88         /*
  89          * since we're only adjusting minutes and seconds,
  90          * don't interfere with hour overflow. This avoids
  91          * messing with unknown time zones but requires your
  92          * RTC not to be off by more than 15 minutes
  93          */
  94         real_seconds = nowtime % 60;
  95         real_minutes = nowtime / 60;
  96         if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1)
  97                 real_minutes += 30;     /* correct for half hour time zone */
  98         real_minutes %= 60;
  99
 100         if (abs(real_minutes - cmos_minutes) < 30) {
 101                 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
 102                         real_seconds = bin2bcd(real_seconds);
 103                         real_minutes = bin2bcd(real_minutes);
 104                 }
 105                 CMOS_WRITE(real_seconds, RTC_SECONDS);
 106                 CMOS_WRITE(real_minutes, RTC_MINUTES);
 107         } else {
 108                 printk(KERN_WARNING
 109                        "set_rtc_mmss: can't update from %d to %d\n",
 110                        cmos_minutes, real_minutes);
 111                 retval = -1;
 112         }
 113
 114         /* The following flags have to be released exactly in this order,
 115          * otherwise the DS1287 will not reset the oscillator and will not
 116          * update precisely 500 ms later.  You won't find this mentioned
 117          * in the Dallas Semiconductor data sheets, but who believes data
 118          * sheets anyway ...                           -- Markus Kuhn
 119          */
 120         CMOS_WRITE(save_control, RTC_CONTROL);
 121         CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
 122         spin_unlock(&rtc_lock);
 123
 124         return retval;
 125 }
 126
 127 void __init plat_time_init(void)
 128 {
 129         u32 start, end;
 130         int i = HZ / 10;
 131
 132         /* Set up the rate of periodic DS1287 interrupts. */
 133         ds1287_set_base_clock(HZ);
 134
 135         if (cpu_has_counter) {
 136                 while (!ds1287_timer_state())
 137                         ;
 138
 139                 start = read_c0_count();
 140
 141                 while (i--)
 142                         while (!ds1287_timer_state())
 143                                 ;
 144
 145                 end = read_c0_count();
 146
 147                 mips_hpt_frequency = (end - start) * 10;
 148                 printk(KERN_INFO "MIPS counter frequency %dHz\n",
 149                         mips_hpt_frequency);
 150         } else if (IOASIC)
 151                 /* For pre-R4k systems we use the I/O ASIC's counter.  */
 152                 dec_ioasic_clocksource_init();
 153
 154         ds1287_clockevent_init(dec_interrupt[DEC_IRQ_RTC]);
 155 }