arch/powerpc/platforms/chrp/time.c

   1 /*
   2  *  arch/ppc/platforms/chrp_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 arch/i386/kernel/time.c
   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/time.h>
  19 #include <linux/timex.h>
  20 #include <linux/kernel_stat.h>
  21 #include <linux/mc146818rtc.h>
  22 #include <linux/init.h>
  23 #include <linux/bcd.h>
  24
  25 #include <asm/io.h>
  26 #include <asm/nvram.h>
  27 #include <asm/prom.h>
  28 #include <asm/sections.h>
  29 #include <asm/time.h>
  30
  31 extern spinlock_t rtc_lock;
  32
  33 static int nvram_as1 = NVRAM_AS1;
  34 static int nvram_as0 = NVRAM_AS0;
  35 static int nvram_data = NVRAM_DATA;
  36
  37 long __init chrp_time_init(void)
  38 {
  39         struct device_node *rtcs;
  40         int base;
  41
  42         rtcs = find_compatible_devices("rtc", "pnpPNP,b00");
  43         if (rtcs == NULL)
  44                 rtcs = find_compatible_devices("rtc", "ds1385-rtc");
  45         if (rtcs == NULL || rtcs->addrs == NULL)
  46                 return 0;
  47         base = rtcs->addrs[0].address;
  48         nvram_as1 = 0;
  49         nvram_as0 = base;
  50         nvram_data = base + 1;
  51
  52         return 0;
  53 }
  54
  55 int chrp_cmos_clock_read(int addr)
  56 {
  57         if (nvram_as1 != 0)
  58                 outb(addr>>8, nvram_as1);
  59         outb(addr, nvram_as0);
  60         return (inb(nvram_data));
  61 }
  62
  63 void chrp_cmos_clock_write(unsigned long val, int addr)
  64 {
  65         if (nvram_as1 != 0)
  66                 outb(addr>>8, nvram_as1);
  67         outb(addr, nvram_as0);
  68         outb(val, nvram_data);
  69         return;
  70 }
  71
  72 /*
  73  * Set the hardware clock. -- Cort
  74  */
  75 int chrp_set_rtc_time(struct rtc_time *tmarg)
  76 {
  77         unsigned char save_control, save_freq_select;
  78         struct rtc_time tm = *tmarg;
  79
  80         spin_lock(&rtc_lock);
  81
  82         save_control = chrp_cmos_clock_read(RTC_CONTROL); /* tell the clock it's being set */
  83
  84         chrp_cmos_clock_write((save_control|RTC_SET), RTC_CONTROL);
  85
  86         save_freq_select = chrp_cmos_clock_read(RTC_FREQ_SELECT); /* stop and reset prescaler */
  87
  88         chrp_cmos_clock_write((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
  89
  90         if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
  91                 BIN_TO_BCD(tm.tm_sec);
  92                 BIN_TO_BCD(tm.tm_min);
  93                 BIN_TO_BCD(tm.tm_hour);
  94                 BIN_TO_BCD(tm.tm_mon);
  95                 BIN_TO_BCD(tm.tm_mday);
  96                 BIN_TO_BCD(tm.tm_year);
  97         }
  98         chrp_cmos_clock_write(tm.tm_sec,RTC_SECONDS);
  99         chrp_cmos_clock_write(tm.tm_min,RTC_MINUTES);
 100         chrp_cmos_clock_write(tm.tm_hour,RTC_HOURS);
 101         chrp_cmos_clock_write(tm.tm_mon,RTC_MONTH);
 102         chrp_cmos_clock_write(tm.tm_mday,RTC_DAY_OF_MONTH);
 103         chrp_cmos_clock_write(tm.tm_year,RTC_YEAR);
 104
 105         /* The following flags have to be released exactly in this order,
 106          * otherwise the DS12887 (popular MC146818A clone with integrated
 107          * battery and quartz) will not reset the oscillator and will not
 108          * update precisely 500 ms later. You won't find this mentioned in
 109          * the Dallas Semiconductor data sheets, but who believes data
 110          * sheets anyway ...                           -- Markus Kuhn
 111          */
 112         chrp_cmos_clock_write(save_control, RTC_CONTROL);
 113         chrp_cmos_clock_write(save_freq_select, RTC_FREQ_SELECT);
 114
 115         spin_unlock(&rtc_lock);
 116         return 0;
 117 }
 118
 119 void chrp_get_rtc_time(struct rtc_time *tm)
 120 {
 121         unsigned int year, mon, day, hour, min, sec;
 122         int uip, i;
 123
 124         /* The Linux interpretation of the CMOS clock register contents:
 125          * When the Update-In-Progress (UIP) flag goes from 1 to 0, the
 126          * RTC registers show the second which has precisely just started.
 127          * Let's hope other operating systems interpret the RTC the same way.
 128          */
 129
 130         /* Since the UIP flag is set for about 2.2 ms and the clock
 131          * is typically written with a precision of 1 jiffy, trying
 132          * to obtain a precision better than a few milliseconds is
 133          * an illusion. Only consistency is interesting, this also
 134          * allows to use the routine for /dev/rtc without a potential
 135          * 1 second kernel busy loop triggered by any reader of /dev/rtc.
 136          */
 137
 138         for ( i = 0; i<1000000; i++) {
 139                 uip = chrp_cmos_clock_read(RTC_FREQ_SELECT);
 140                 sec = chrp_cmos_clock_read(RTC_SECONDS);
 141                 min = chrp_cmos_clock_read(RTC_MINUTES);
 142                 hour = chrp_cmos_clock_read(RTC_HOURS);
 143                 day = chrp_cmos_clock_read(RTC_DAY_OF_MONTH);
 144                 mon = chrp_cmos_clock_read(RTC_MONTH);
 145                 year = chrp_cmos_clock_read(RTC_YEAR);
 146                 uip |= chrp_cmos_clock_read(RTC_FREQ_SELECT);
 147                 if ((uip & RTC_UIP)==0) break;
 148         }
 149
 150         if (!(chrp_cmos_clock_read(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
 151                 BCD_TO_BIN(sec);
 152                 BCD_TO_BIN(min);
 153                 BCD_TO_BIN(hour);
 154                 BCD_TO_BIN(day);
 155                 BCD_TO_BIN(mon);
 156                 BCD_TO_BIN(year);
 157         }
 158         if (year < 70)
 159                 year += 100;
 160         tm->tm_sec = sec;
 161         tm->tm_min = min;
 162         tm->tm_hour = hour;
 163         tm->tm_mday = day;
 164         tm->tm_mon = mon;
 165         tm->tm_year = year;
 166 }
 167
 168
 169 void __init chrp_calibrate_decr(void)
 170 {
 171         struct device_node *cpu;
 172         unsigned int freq, *fp;
 173
 174         /*
 175          * The cpu node should have a timebase-frequency property
 176          * to tell us the rate at which the decrementer counts.
 177          */
 178         freq = 16666000;                /* hardcoded default */
 179         cpu = find_type_devices("cpu");
 180         if (cpu != 0) {
 181                 fp = (unsigned int *)
 182                         get_property(cpu, "timebase-frequency", NULL);
 183                 if (fp != 0)
 184                         freq = *fp;
 185         }
 186         ppc_tb_freq = freq;
 187 }