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