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 #include <linux/ioport.h>
  25
  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         struct resource r;
  42         int base;
  43
  44         rtcs = find_compatible_devices("rtc", "pnpPNP,b00");
  45         if (rtcs == NULL)
  46                 rtcs = find_compatible_devices("rtc", "ds1385-rtc");
  47         if (rtcs == NULL || of_address_to_resource(rtcs, 0, &r))
  48                 return 0;
  49
  50         base = r.start;
  51         nvram_as1 = 0;
  52         nvram_as0 = base;
  53         nvram_data = base + 1;
  54
  55         return 0;
  56 }
  57
  58 int chrp_cmos_clock_read(int addr)
  59 {
  60         if (nvram_as1 != 0)
  61                 outb(addr>>8, nvram_as1);
  62         outb(addr, nvram_as0);
  63         return (inb(nvram_data));
  64 }
  65
  66 void chrp_cmos_clock_write(unsigned long val, int addr)
  67 {
  68         if (nvram_as1 != 0)
  69                 outb(addr>>8, nvram_as1);
  70         outb(addr, nvram_as0);
  71         outb(val, nvram_data);
  72         return;
  73 }
  74
  75 /*
  76  * Set the hardware clock. -- Cort
  77  */
  78 int chrp_set_rtc_time(struct rtc_time *tmarg)
  79 {
  80         unsigned char save_control, save_freq_select;
  81         struct rtc_time tm = *tmarg;
  82
  83         spin_lock(&rtc_lock);
  84
  85         save_control = chrp_cmos_clock_read(RTC_CONTROL); /* tell the clock it's being set */
  86
  87         chrp_cmos_clock_write((save_control|RTC_SET), RTC_CONTROL);
  88
  89         save_freq_select = chrp_cmos_clock_read(RTC_FREQ_SELECT); /* stop and reset prescaler */
  90
  91         chrp_cmos_clock_write((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
  92
  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 void chrp_get_rtc_time(struct rtc_time *tm)
 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                 BCD_TO_BIN(sec);
 155                 BCD_TO_BIN(min);
 156                 BCD_TO_BIN(hour);
 157                 BCD_TO_BIN(day);
 158                 BCD_TO_BIN(mon);
 159                 BCD_TO_BIN(year);
 160         }
 161         if (year < 70)
 162                 year += 100;
 163         tm->tm_sec = sec;
 164         tm->tm_min = min;
 165         tm->tm_hour = hour;
 166         tm->tm_mday = day;
 167         tm->tm_mon = mon;
 168         tm->tm_year = year;
 169 }
 170
 171
 172 void __init chrp_calibrate_decr(void)
 173 {
 174         struct device_node *cpu;
 175         unsigned int freq, *fp;
 176
 177         /*
 178          * The cpu node should have a timebase-frequency property
 179          * to tell us the rate at which the decrementer counts.
 180          */
 181         freq = 16666000;                /* hardcoded default */
 182         cpu = find_type_devices("cpu");
 183         if (cpu != 0) {
 184                 fp = (unsigned int *)
 185                         get_property(cpu, "timebase-frequency", NULL);
 186                 if (fp != 0)
 187                         freq = *fp;
 188         }
 189         ppc_tb_freq = freq;
 190 }