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 void read_persistent_clock(struct timespec *ts)
  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         ts->tv_sec = mktime(year, mon, day, hour, min, sec);
  57         ts->tv_nsec = 0;
  58 }
  59
  60 /*
  61  * In order to set the CMOS clock precisely, rtc_mips_set_mmss has to
  62  * be called 500 ms after the second nowtime has started, because when
  63  * nowtime is written into the registers of the CMOS clock, it will
  64  * jump to the next second precisely 500 ms later.  Check the Dallas
  65  * DS1287 data sheet for details.
  66  */
  67 int rtc_mips_set_mmss(unsigned long nowtime)
  68 {
  69         int retval = 0;
  70         int real_seconds, real_minutes, cmos_minutes;
  71         unsigned char save_control, save_freq_select;
  72
  73         /* irq are locally disabled here */
  74         spin_lock(&rtc_lock);
  75         /* tell the clock it's being set */
  76         save_control = CMOS_READ(RTC_CONTROL);
  77         CMOS_WRITE((save_control | RTC_SET), RTC_CONTROL);
  78
  79         /* stop and reset prescaler */
  80         save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
  81         CMOS_WRITE((save_freq_select | RTC_DIV_RESET2), RTC_FREQ_SELECT);
  82
  83         cmos_minutes = CMOS_READ(RTC_MINUTES);
  84         if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
  85                 cmos_minutes = bcd2bin(cmos_minutes);
  86
  87         /*
  88          * since we're only adjusting minutes and seconds,
  89          * don't interfere with hour overflow. This avoids
  90          * messing with unknown time zones but requires your
  91          * RTC not to be off by more than 15 minutes
  92          */
  93         real_seconds = nowtime % 60;
  94         real_minutes = nowtime / 60;
  95         if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1)
  96                 real_minutes += 30;     /* correct for half hour time zone */
  97         real_minutes %= 60;
  98
  99         if (abs(real_minutes - cmos_minutes) < 30) {
 100                 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
 101                         real_seconds = bin2bcd(real_seconds);
 102                         real_minutes = bin2bcd(real_minutes);
 103                 }
 104                 CMOS_WRITE(real_seconds, RTC_SECONDS);
 105                 CMOS_WRITE(real_minutes, RTC_MINUTES);
 106         } else {
 107                 printk_once(KERN_NOTICE
 108                        "set_rtc_mmss: can't update from %d to %d\n",
 109                        cmos_minutes, real_minutes);
 110                 retval = -1;
 111         }
 112
 113         /* The following flags have to be released exactly in this order,
 114          * otherwise the DS1287 will not reset the oscillator and will not
 115          * update precisely 500 ms later.  You won't find this mentioned
 116          * in the Dallas Semiconductor data sheets, but who believes data
 117          * sheets anyway ...                           -- Markus Kuhn
 118          */
 119         CMOS_WRITE(save_control, RTC_CONTROL);
 120         CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
 121         spin_unlock(&rtc_lock);
 122
 123         return retval;
 124 }
 125
 126 void __init plat_time_init(void)
 127 {
 128         int ioasic_clock = 0;
 129         u32 start, end;
 130         int i = HZ / 8;
 131
 132         /* Set up the rate of periodic DS1287 interrupts. */
 133         ds1287_set_base_clock(HZ);
 134
 135         /* On some I/O ASIC systems we have the I/O ASIC's counter.  */
 136         if (IOASIC)
 137                 ioasic_clock = dec_ioasic_clocksource_init() == 0;
 138         if (cpu_has_counter) {
 139                 ds1287_timer_state();
 140                 while (!ds1287_timer_state())
 141                         ;
 142
 143                 start = read_c0_count();
 144
 145                 while (i--)
 146                         while (!ds1287_timer_state())
 147                                 ;
 148
 149                 end = read_c0_count();
 150
 151                 mips_hpt_frequency = (end - start) * 8;
 152                 printk(KERN_INFO "MIPS counter frequency %dHz\n",
 153                         mips_hpt_frequency);
 154
 155                 /*
 156                  * All R4k DECstations suffer from the CP0 Count erratum,
 157                  * so we can't use the timer as a clock source, and a clock
 158                  * event both at a time.  An accurate wall clock is more
 159                  * important than a high-precision interval timer so only
 160                  * use the timer as a clock source, and not a clock event
 161                  * if there's no I/O ASIC counter available to serve as a
 162                  * clock source.
 163                  */
 164                 if (!ioasic_clock) {
 165                         init_r4k_clocksource();
 166                         mips_hpt_frequency = 0;
 167                 }
 168         }
 169
 170         ds1287_clockevent_init(dec_interrupt[DEC_IRQ_RTC]);
 171 }