arch/ppc/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/segment.h>
  26 #include <asm/io.h>
  27 #include <asm/nvram.h>
  28 #include <asm/prom.h>
  29 #include <asm/sections.h>
  30 #include <asm/time.h>
  31
  32 extern spinlock_t rtc_lock;
  33
  34 static int nvram_as1 = NVRAM_AS1;
  35 static int nvram_as0 = NVRAM_AS0;
  36 static int nvram_data = NVRAM_DATA;
  37
  38 long __init chrp_time_init(void)
  39 {
  40         struct device_node *rtcs;
  41         int base;
  42
  43         rtcs = find_compatible_devices("rtc", "pnpPNP,b00");
  44         if (rtcs == NULL)
  45                 rtcs = find_compatible_devices("rtc", "ds1385-rtc");
  46         if (rtcs == NULL || rtcs->addrs == NULL)
  47                 return 0;
  48         base = rtcs->addrs[0].address;
  49         nvram_as1 = 0;
  50         nvram_as0 = base;
  51         nvram_data = base + 1;
  52
  53         return 0;
  54 }
  55
  56 int __chrp chrp_cmos_clock_read(int addr)
  57 {
  58         if (nvram_as1 != 0)
  59                 outb(addr>>8, nvram_as1);
  60         outb(addr, nvram_as0);
  61         return (inb(nvram_data));
  62 }
  63
  64 void __chrp chrp_cmos_clock_write(unsigned long val, int addr)
  65 {
  66         if (nvram_as1 != 0)
  67                 outb(addr>>8, nvram_as1);
  68         outb(addr, nvram_as0);
  69         outb(val, nvram_data);
  70         return;
  71 }
  72
  73 /*
  74  * Set the hardware clock. -- Cort
  75  */
  76 int __chrp chrp_set_rtc_time(unsigned long nowtime)
  77 {
  78         unsigned char save_control, save_freq_select;
  79         struct rtc_time tm;
  80
  81         spin_lock(&rtc_lock);
  82         to_tm(nowtime, &tm);
  83
  84         save_control = chrp_cmos_clock_read(RTC_CONTROL); /* tell the clock it's being set */
  85
  86         chrp_cmos_clock_write((save_control|RTC_SET), RTC_CONTROL);
  87
  88         save_freq_select = chrp_cmos_clock_read(RTC_FREQ_SELECT); /* stop and reset prescaler */
  89
  90         chrp_cmos_clock_write((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
  91
  92         tm.tm_year -= 1900;
  93         if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
  94                 BIN_TO_BCD(tm.tm_sec);
  95                 BIN_TO_BCD(tm.tm_min);
  96                 BIN_TO_BCD(tm.tm_hour);
  97                 BIN_TO_BCD(tm.tm_mon);
  98                 BIN_TO_BCD(tm.tm_mday);
  99                 BIN_TO_BCD(tm.tm_year);
 100         }
 101         chrp_cmos_clock_write(tm.tm_sec,RTC_SECONDS);
 102         chrp_cmos_clock_write(tm.tm_min,RTC_MINUTES);
 103         chrp_cmos_clock_write(tm.tm_hour,RTC_HOURS);
 104         chrp_cmos_clock_write(tm.tm_mon,RTC_MONTH);
 105         chrp_cmos_clock_write(tm.tm_mday,RTC_DAY_OF_MONTH);
 106         chrp_cmos_clock_write(tm.tm_year,RTC_YEAR);
 107
 108         /* The following flags have to be released exactly in this order,
 109          * otherwise the DS12887 (popular MC146818A clone with integrated
 110          * battery and quartz) will not reset the oscillator and will not
 111          * update precisely 500 ms later. You won't find this mentioned in
 112          * the Dallas Semiconductor data sheets, but who believes data
 113          * sheets anyway ...                           -- Markus Kuhn
 114          */
 115         chrp_cmos_clock_write(save_control, RTC_CONTROL);
 116         chrp_cmos_clock_write(save_freq_select, RTC_FREQ_SELECT);
 117
 118         spin_unlock(&rtc_lock);
 119         return 0;
 120 }
 121
 122 unsigned long __chrp chrp_get_rtc_time(void)
 123 {
 124         unsigned int year, mon, day, hour, min, sec;
 125         int uip, i;
 126
 127         /* The Linux interpretation of the CMOS clock register contents:
 128          * When the Update-In-Progress (UIP) flag goes from 1 to 0, the
 129          * RTC registers show the second which has precisely just started.
 130          * Let's hope other operating systems interpret the RTC the same way.
 131          */
 132
 133         /* Since the UIP flag is set for about 2.2 ms and the clock
 134          * is typically written with a precision of 1 jiffy, trying
 135          * to obtain a precision better than a few milliseconds is
 136          * an illusion. Only consistency is interesting, this also
 137          * allows to use the routine for /dev/rtc without a potential
 138          * 1 second kernel busy loop triggered by any reader of /dev/rtc.
 139          */
 140
 141         for ( i = 0; i<1000000; i++) {
 142                 uip = chrp_cmos_clock_read(RTC_FREQ_SELECT);
 143                 sec = chrp_cmos_clock_read(RTC_SECONDS);
 144                 min = chrp_cmos_clock_read(RTC_MINUTES);
 145                 hour = chrp_cmos_clock_read(RTC_HOURS);
 146                 day = chrp_cmos_clock_read(RTC_DAY_OF_MONTH);
 147                 mon = chrp_cmos_clock_read(RTC_MONTH);
 148                 year = chrp_cmos_clock_read(RTC_YEAR);
 149                 uip |= chrp_cmos_clock_read(RTC_FREQ_SELECT);
 150                 if ((uip & RTC_UIP)==0) break;
 151         }
 152
 153         if (!(chrp_cmos_clock_read(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
 154           {
 155             BCD_TO_BIN(sec);
 156             BCD_TO_BIN(min);
 157             BCD_TO_BIN(hour);
 158             BCD_TO_BIN(day);
 159             BCD_TO_BIN(mon);
 160             BCD_TO_BIN(year);
 161           }
 162         if ((year += 1900) < 1970)
 163                 year += 100;
 164         return mktime(year, mon, day, hour, min, sec);
 165 }
 166
 167
 168 void __init chrp_calibrate_decr(void)
 169 {
 170         struct device_node *cpu;
 171         unsigned int freq, *fp;
 172
 173         if (via_calibrate_decr())
 174                 return;
 175
 176         /*
 177          * The cpu node should have a timebase-frequency property
 178          * to tell us the rate at which the decrementer counts.
 179          */
 180         freq = 16666000;                /* hardcoded default */
 181         cpu = find_type_devices("cpu");
 182         if (cpu != 0) {
 183                 fp = (unsigned int *)
 184                         get_property(cpu, "timebase-frequency", NULL);
 185                 if (fp != 0)
 186                         freq = *fp;
 187         }
 188         printk("time_init: decrementer frequency = %u.%.6u MHz\n",
 189                freq/1000000, freq%1000000);
 190         tb_ticks_per_jiffy = freq / HZ;
 191         tb_to_us = mulhwu_scale_factor(freq, 1000000);
 192 }