i386/linux/linux-2.3.21/arch/ppc/kernel/chrp_time.c

   1 /*
   2  *  linux/arch/i386/kernel/time.c
   3  *
   4  *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
   5  *
   6  * Adapted for PowerPC (PreP) by Gary Thomas
   7  * Modified by Cort Dougan (cort@cs.nmt.edu)
   8  *  copied and modified from intel version
   9  *
  10  */
  11 #include <linux/errno.h>
  12 #include <linux/sched.h>
  13 #include <linux/kernel.h>
  14 #include <linux/param.h>
  15 #include <linux/string.h>
  16 #include <linux/mm.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/timex.h>
  19 #include <linux/kernel_stat.h>
  20 #include <linux/mc146818rtc.h>
  21 #include <linux/init.h>
  22
  23 #include <asm/segment.h>
  24 #include <asm/io.h>
  25 #include <asm/processor.h>
  26 #include <asm/nvram.h>
  27 #include <asm/prom.h>
  28 #include "time.h"
  29
  30 static int nvram_as1 = NVRAM_AS1;
  31 static int nvram_as0 = NVRAM_AS0;
  32 static int nvram_data = NVRAM_DATA;
  33
  34 void __init chrp_time_init(void)
  35 {
  36         struct device_node *rtcs;
  37         int base;
  38
  39         rtcs = find_compatible_devices("rtc", "pnpPNP,b00");
  40         if (rtcs == NULL || rtcs->addrs == NULL)
  41                 return;
  42         base = rtcs->addrs[0].address;
  43         nvram_as1 = 0;
  44         nvram_as0 = base;
  45         nvram_data = base + 1;
  46 }
  47
  48 int chrp_cmos_clock_read(int addr)
  49 {
  50         if (nvram_as1 != 0)
  51                 outb(addr>>8, nvram_as1);
  52         outb(addr, nvram_as0);
  53         return (inb(nvram_data));
  54 }
  55
  56 void chrp_cmos_clock_write(unsigned long val, int addr)
  57 {
  58         if (nvram_as1 != 0)
  59                 outb(addr>>8, nvram_as1);
  60         outb(addr, nvram_as0);
  61         outb(val, nvram_data);
  62         return;
  63 }
  64
  65 /*
  66  * Set the hardware clock. -- Cort
  67  */
  68 int chrp_set_rtc_time(unsigned long nowtime)
  69 {
  70         unsigned char save_control, save_freq_select;
  71         struct rtc_time tm;
  72
  73         to_tm(nowtime, &tm);
  74
  75         save_control = chrp_cmos_clock_read(RTC_CONTROL); /* tell the clock it's being set */
  76
  77         chrp_cmos_clock_write((save_control|RTC_SET), RTC_CONTROL);
  78
  79         save_freq_select = chrp_cmos_clock_read(RTC_FREQ_SELECT); /* stop and reset prescaler */
  80
  81         chrp_cmos_clock_write((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
  82
  83         tm.tm_year -= 1900;
  84         if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
  85                 BIN_TO_BCD(tm.tm_sec);
  86                 BIN_TO_BCD(tm.tm_min);
  87                 BIN_TO_BCD(tm.tm_hour);
  88                 BIN_TO_BCD(tm.tm_mon);
  89                 BIN_TO_BCD(tm.tm_mday);
  90                 BIN_TO_BCD(tm.tm_year);
  91         }
  92         chrp_cmos_clock_write(tm.tm_sec,RTC_SECONDS);
  93         chrp_cmos_clock_write(tm.tm_min,RTC_MINUTES);
  94         chrp_cmos_clock_write(tm.tm_hour,RTC_HOURS);
  95         chrp_cmos_clock_write(tm.tm_mon,RTC_MONTH);
  96         chrp_cmos_clock_write(tm.tm_mday,RTC_DAY_OF_MONTH);
  97         chrp_cmos_clock_write(tm.tm_year,RTC_YEAR);
  98
  99         /* The following flags have to be released exactly in this order,
 100          * otherwise the DS12887 (popular MC146818A clone with integrated
 101          * battery and quartz) will not reset the oscillator and will not
 102          * update precisely 500 ms later. You won't find this mentioned in
 103          * the Dallas Semiconductor data sheets, but who believes data
 104          * sheets anyway ...                           -- Markus Kuhn
 105          */
 106         chrp_cmos_clock_write(save_control, RTC_CONTROL);
 107         chrp_cmos_clock_write(save_freq_select, RTC_FREQ_SELECT);
 108
 109         if ( (time_state == TIME_ERROR) || (time_state == TIME_BAD) )
 110                 time_state = TIME_OK;
 111         return 0;
 112 }
 113
 114 unsigned long chrp_get_rtc_time(void)
 115 {
 116         unsigned int year, mon, day, hour, min, sec;
 117         int i;
 118
 119         /* The Linux interpretation of the CMOS clock register contents:
 120          * When the Update-In-Progress (UIP) flag goes from 1 to 0, the
 121          * RTC registers show the second which has precisely just started.
 122          * Let's hope other operating systems interpret the RTC the same way.
 123          */
 124         /* read RTC exactly on falling edge of update flag */
 125         for (i = 0 ; i < 1000000 ; i++) /* may take up to 1 second... */
 126                 if (chrp_cmos_clock_read(RTC_FREQ_SELECT) & RTC_UIP)
 127                         break;
 128         for (i = 0 ; i < 1000000 ; i++) /* must try at least 2.228 ms */
 129                 if (!(chrp_cmos_clock_read(RTC_FREQ_SELECT) & RTC_UIP))
 130                         break;
 131         do { /* Isn't this overkill ? UIP above should guarantee consistency */
 132                 sec = chrp_cmos_clock_read(RTC_SECONDS);
 133                 min = chrp_cmos_clock_read(RTC_MINUTES);
 134                 hour = chrp_cmos_clock_read(RTC_HOURS);
 135                 day = chrp_cmos_clock_read(RTC_DAY_OF_MONTH);
 136                 mon = chrp_cmos_clock_read(RTC_MONTH);
 137                 year = chrp_cmos_clock_read(RTC_YEAR);
 138         } while (sec != chrp_cmos_clock_read(RTC_SECONDS));
 139         if (!(chrp_cmos_clock_read(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
 140           {
 141             BCD_TO_BIN(sec);
 142             BCD_TO_BIN(min);
 143             BCD_TO_BIN(hour);
 144             BCD_TO_BIN(day);
 145             BCD_TO_BIN(mon);
 146             BCD_TO_BIN(year);
 147           }
 148         if ((year += 1900) < 1970)
 149                 year += 100;
 150         return mktime(year, mon, day, hour, min, sec);
 151 }
 152
 153
 154 void __init chrp_calibrate_decr(void)
 155 {
 156         struct device_node *cpu;
 157         int *fp, divisor;
 158         unsigned long freq;
 159
 160         if (via_calibrate_decr())
 161                 return;
 162
 163         /*
 164          * The cpu node should have a timebase-frequency property
 165          * to tell us the rate at which the decrementer counts.
 166          */
 167         freq = 16666000;                /* hardcoded default */
 168         cpu = find_type_devices("cpu");
 169         if (cpu != 0) {
 170                 fp = (int *) get_property(cpu, "timebase-frequency", NULL);
 171                 if (fp != 0)
 172                         freq = *fp;
 173         }
 174         freq *= 60;     /* try to make freq/1e6 an integer */
 175         divisor = 60;
 176         printk("time_init: decrementer frequency = %lu/%d\n", freq, divisor);
 177         decrementer_count = freq / HZ / divisor;
 178         count_period_num = divisor;
 179         count_period_den = freq / 1000000;
 180 }