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/errno.h>
  13 #include <linux/init.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/kernel.h>
  16 #include <linux/mc146818rtc.h>
  17 #include <linux/mm.h>
  18 #include <linux/module.h>
  19 #include <linux/param.h>
  20 #include <linux/sched.h>
  21 #include <linux/string.h>
  22 #include <linux/time.h>
  23 #include <linux/types.h>
  24
  25 #include <asm/bootinfo.h>
  26 #include <asm/cpu.h>
  27 #include <asm/div64.h>
  28 #include <asm/io.h>
  29 #include <asm/irq.h>
  30 #include <asm/mipsregs.h>
  31 #include <asm/sections.h>
  32 #include <asm/time.h>
  33
  34 #include <asm/dec/interrupts.h>
  35 #include <asm/dec/ioasic.h>
  36 #include <asm/dec/ioasic_addrs.h>
  37 #include <asm/dec/machtype.h>
  38
  39 static unsigned long dec_rtc_get_time(void)
  40 {
  41         unsigned int year, mon, day, hour, min, sec, real_year;
  42         unsigned long flags;
  43
  44         spin_lock_irqsave(&rtc_lock, flags);
  45
  46         do {
  47                 sec = CMOS_READ(RTC_SECONDS);
  48                 min = CMOS_READ(RTC_MINUTES);
  49                 hour = CMOS_READ(RTC_HOURS);
  50                 day = CMOS_READ(RTC_DAY_OF_MONTH);
  51                 mon = CMOS_READ(RTC_MONTH);
  52                 year = CMOS_READ(RTC_YEAR);
  53                 /*
  54                  * The PROM will reset the year to either '72 or '73.
  55                  * Therefore we store the real year separately, in one
  56                  * of unused BBU RAM locations.
  57                  */
  58                 real_year = CMOS_READ(RTC_DEC_YEAR);
  59         } while (sec != CMOS_READ(RTC_SECONDS));
  60
  61         spin_unlock_irqrestore(&rtc_lock, flags);
  62
  63         if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
  64                 sec = BCD2BIN(sec);
  65                 min = BCD2BIN(min);
  66                 hour = BCD2BIN(hour);
  67                 day = BCD2BIN(day);
  68                 mon = BCD2BIN(mon);
  69                 year = BCD2BIN(year);
  70         }
  71
  72         year += real_year - 72 + 2000;
  73
  74         return mktime(year, mon, day, hour, min, sec);
  75 }
  76
  77 /*
  78  * In order to set the CMOS clock precisely, dec_rtc_set_mmss has to
  79  * be called 500 ms after the second nowtime has started, because when
  80  * nowtime is written into the registers of the CMOS clock, it will
  81  * jump to the next second precisely 500 ms later.  Check the Dallas
  82  * DS1287 data sheet for details.
  83  */
  84 static int dec_rtc_set_mmss(unsigned long nowtime)
  85 {
  86         int retval = 0;
  87         int real_seconds, real_minutes, cmos_minutes;
  88         unsigned char save_control, save_freq_select;
  89
  90         /* irq are locally disabled here */
  91         spin_lock(&rtc_lock);
  92         /* tell the clock it's being set */
  93         save_control = CMOS_READ(RTC_CONTROL);
  94         CMOS_WRITE((save_control | RTC_SET), RTC_CONTROL);
  95
  96         /* stop and reset prescaler */
  97         save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
  98         CMOS_WRITE((save_freq_select | RTC_DIV_RESET2), RTC_FREQ_SELECT);
  99
 100         cmos_minutes = CMOS_READ(RTC_MINUTES);
 101         if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
 102                 cmos_minutes = BCD2BIN(cmos_minutes);
 103
 104         /*
 105          * since we're only adjusting minutes and seconds,
 106          * don't interfere with hour overflow. This avoids
 107          * messing with unknown time zones but requires your
 108          * RTC not to be off by more than 15 minutes
 109          */
 110         real_seconds = nowtime % 60;
 111         real_minutes = nowtime / 60;
 112         if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1)
 113                 real_minutes += 30;     /* correct for half hour time zone */
 114         real_minutes %= 60;
 115
 116         if (abs(real_minutes - cmos_minutes) < 30) {
 117                 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
 118                         real_seconds = BIN2BCD(real_seconds);
 119                         real_minutes = BIN2BCD(real_minutes);
 120                 }
 121                 CMOS_WRITE(real_seconds, RTC_SECONDS);
 122                 CMOS_WRITE(real_minutes, RTC_MINUTES);
 123         } else {
 124                 printk(KERN_WARNING
 125                        "set_rtc_mmss: can't update from %d to %d\n",
 126                        cmos_minutes, real_minutes);
 127                 retval = -1;
 128         }
 129
 130         /* The following flags have to be released exactly in this order,
 131          * otherwise the DS1287 will not reset the oscillator and will not
 132          * update precisely 500 ms later.  You won't find this mentioned
 133          * in the Dallas Semiconductor data sheets, but who believes data
 134          * sheets anyway ...                           -- Markus Kuhn
 135          */
 136         CMOS_WRITE(save_control, RTC_CONTROL);
 137         CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
 138         spin_unlock(&rtc_lock);
 139
 140         return retval;
 141 }
 142
 143
 144 static int dec_timer_state(void)
 145 {
 146         return (CMOS_READ(RTC_REG_C) & RTC_PF) != 0;
 147 }
 148
 149 static void dec_timer_ack(void)
 150 {
 151         CMOS_READ(RTC_REG_C);                   /* Ack the RTC interrupt.  */
 152 }
 153
 154 static cycle_t dec_ioasic_hpt_read(void)
 155 {
 156         /*
 157          * The free-running counter is 32-bit which is good for about
 158          * 2 minutes, 50 seconds at possible count rates of up to 25MHz.
 159          */
 160         return ioasic_read(IO_REG_FCTR);
 161 }
 162
 163
 164 void __init dec_time_init(void)
 165 {
 166         rtc_mips_get_time = dec_rtc_get_time;
 167         rtc_mips_set_mmss = dec_rtc_set_mmss;
 168
 169         mips_timer_state = dec_timer_state;
 170         mips_timer_ack = dec_timer_ack;
 171
 172         if (!cpu_has_counter && IOASIC)
 173                 /* For pre-R4k systems we use the I/O ASIC's counter.  */
 174                 clocksource_mips.read = dec_ioasic_hpt_read;
 175
 176         /* Set up the rate of periodic DS1287 interrupts.  */
 177         CMOS_WRITE(RTC_REF_CLCK_32KHZ | (16 - __ffs(HZ)), RTC_REG_A);
 178 }
 179
 180 void __init plat_timer_setup(struct irqaction *irq)
 181 {
 182         setup_irq(dec_interrupt[DEC_IRQ_RTC], irq);
 183
 184         /* Enable periodic DS1287 interrupts.  */
 185         CMOS_WRITE(CMOS_READ(RTC_REG_B) | RTC_PIE, RTC_REG_B);
 186 }