arch/ppc/kernel/prep_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/init.h>
  21
  22 #include <asm/init.h>
  23 #include <asm/segment.h>
  24 #include <asm/io.h>
  25 #include <asm/processor.h>
  26 #include <asm/machdep.h>
  27 #include <asm/prep_nvram.h>
  28 #include <asm/mk48t59.h>
  29
  30 #include "time.h"
  31
  32 /*
  33  * The motorola uses the m48t18 rtc (includes DS1643) whose registers
  34  * are at a higher end of nvram (1ff8-1fff) than the ibm mc146818
  35  * rtc (ds1386) which has regs at addr 0-d).  The intel gets
  36  * past this because the bios emulates the mc146818.
  37  *
  38  * Why in the world did they have to use different clocks?
  39  *
  40  * Right now things are hacked to check which machine we're on then
  41  * use the appropriate macro.  This is very very ugly and I should
  42  * probably have a function that checks which machine we're on then
  43  * does things correctly transparently or a function pointer which
  44  * is setup at boot time to use the correct addresses.
  45  * -- Cort
  46  */
  47
  48 /*
  49  * Set the hardware clock. -- Cort
  50  */
  51 __prep
  52 int mc146818_set_rtc_time(unsigned long nowtime)
  53 {
  54         unsigned char save_control, save_freq_select;
  55         struct rtc_time tm;
  56
  57         to_tm(nowtime, &tm);
  58
  59         /* tell the clock it's being set */
  60         save_control = CMOS_READ(RTC_CONTROL);
  61
  62         CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
  63
  64         /* stop and reset prescaler */
  65         save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
  66
  67         CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
  68
  69         tm.tm_year = (tm.tm_year - 1900) % 100;
  70         if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
  71                 BIN_TO_BCD(tm.tm_sec);
  72                 BIN_TO_BCD(tm.tm_min);
  73                 BIN_TO_BCD(tm.tm_hour);
  74                 BIN_TO_BCD(tm.tm_mon);
  75                 BIN_TO_BCD(tm.tm_mday);
  76                 BIN_TO_BCD(tm.tm_year);
  77         }
  78         CMOS_WRITE(tm.tm_sec,  RTC_SECONDS);
  79         CMOS_WRITE(tm.tm_min,  RTC_MINUTES);
  80         CMOS_WRITE(tm.tm_hour, RTC_HOURS);
  81         CMOS_WRITE(tm.tm_mon,  RTC_MONTH);
  82         CMOS_WRITE(tm.tm_mday, RTC_DAY_OF_MONTH);
  83         CMOS_WRITE(tm.tm_year, RTC_YEAR);
  84
  85         /* The following flags have to be released exactly in this order,
  86          * otherwise the DS12887 (popular MC146818A clone with integrated
  87          * battery and quartz) will not reset the oscillator and will not
  88          * update precisely 500 ms later. You won't find this mentioned in
  89          * the Dallas Semiconductor data sheets, but who believes data
  90          * sheets anyway ...                           -- Markus Kuhn
  91          */
  92         CMOS_WRITE(save_control,     RTC_CONTROL);
  93         CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
  94
  95         return 0;
  96 }
  97
  98 __prep
  99 unsigned long mc146818_get_rtc_time(void)
 100 {
 101         unsigned int year, mon, day, hour, min, sec;
 102         int i;
 103
 104         /* The Linux interpretation of the CMOS clock register contents:
 105          * When the Update-In-Progress (UIP) flag goes from 1 to 0, the
 106          * RTC registers show the second which has precisely just started.
 107          * Let's hope other operating systems interpret the RTC the same way.
 108          */
 109         /* read RTC exactly on falling edge of update flag */
 110         for (i = 0 ; i < 1000000 ; i++) /* may take up to 1 second... */
 111                 if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP)
 112                         break;
 113         for (i = 0 ; i < 1000000 ; i++) /* must try at least 2.228 ms */
 114                 if (!(CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
 115                         break;
 116         do { /* Isn't this overkill ? UIP above should guarantee consistency */
 117                 sec = CMOS_READ(RTC_SECONDS);
 118                 min = CMOS_READ(RTC_MINUTES);
 119                 hour = CMOS_READ(RTC_HOURS);
 120                 day = CMOS_READ(RTC_DAY_OF_MONTH);
 121                 mon = CMOS_READ(RTC_MONTH);
 122                 year = CMOS_READ(RTC_YEAR);
 123         } while (sec != CMOS_READ(RTC_SECONDS));
 124         if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)
 125             || RTC_ALWAYS_BCD)
 126         {
 127                 BCD_TO_BIN(sec);
 128                 BCD_TO_BIN(min);
 129                 BCD_TO_BIN(hour);
 130                 BCD_TO_BIN(day);
 131                 BCD_TO_BIN(mon);
 132                 BCD_TO_BIN(year);
 133         }
 134         if ((year += 1900) < 1970)
 135                 year += 100;
 136         return mktime(year, mon, day, hour, min, sec);
 137 }
 138
 139 __prep
 140 int mk48t59_set_rtc_time(unsigned long nowtime)
 141 {
 142         unsigned char save_control;
 143         struct rtc_time tm;
 144
 145
 146         to_tm(nowtime, &tm);
 147
 148         /* tell the clock it's being written */
 149         save_control = ppc_md.nvram_read_val(MK48T59_RTC_CONTROLA);
 150
 151         ppc_md.nvram_write_val(MK48T59_RTC_CONTROLA,
 152                              (save_control | MK48T59_RTC_CA_WRITE));
 153
 154         tm.tm_year = (tm.tm_year - 1900) % 100;
 155         BIN_TO_BCD(tm.tm_sec);
 156         BIN_TO_BCD(tm.tm_min);
 157         BIN_TO_BCD(tm.tm_hour);
 158         BIN_TO_BCD(tm.tm_mon);
 159         BIN_TO_BCD(tm.tm_mday);
 160         BIN_TO_BCD(tm.tm_year);
 161
 162         ppc_md.nvram_write_val(MK48T59_RTC_SECONDS,      tm.tm_sec);
 163         ppc_md.nvram_write_val(MK48T59_RTC_MINUTES,      tm.tm_min);
 164         ppc_md.nvram_write_val(MK48T59_RTC_HOURS,        tm.tm_hour);
 165         ppc_md.nvram_write_val(MK48T59_RTC_MONTH,        tm.tm_mon);
 166         ppc_md.nvram_write_val(MK48T59_RTC_DAY_OF_MONTH, tm.tm_mday);
 167         ppc_md.nvram_write_val(MK48T59_RTC_YEAR,         tm.tm_year);
 168
 169         /* Turn off the write bit. */
 170         ppc_md.nvram_write_val(MK48T59_RTC_CONTROLA, save_control);
 171
 172         return 0;
 173 }
 174
 175 __prep
 176 unsigned long mk48t59_get_rtc_time(void)
 177 {
 178         unsigned char save_control;
 179         unsigned int year, mon, day, hour, min, sec;
 180         int i;
 181
 182         /* Make sure the time is not stopped. */
 183         save_control = ppc_md.nvram_read_val(MK48T59_RTC_CONTROLB);
 184
 185         ppc_md.nvram_write_val(MK48T59_RTC_CONTROLA,
 186                              (save_control & (~MK48T59_RTC_CB_STOP)));
 187
 188         /* Now make sure the read bit is off so the value will change. */
 189         save_control = ppc_md.nvram_read_val(MK48T59_RTC_CONTROLA);
 190         save_control &= ~MK48T59_RTC_CA_READ;
 191         ppc_md.nvram_write_val(MK48T59_RTC_CONTROLA, save_control);
 192
 193         /* Read the seconds value to see when it changes. */
 194         sec = ppc_md.nvram_read_val(MK48T59_RTC_SECONDS);
 195
 196         /* Wait until the seconds value changes, then read the value. */
 197         for (i = 0 ; i < 1000000 ; i++) { /* may take up to 1 second... */
 198            if (ppc_md.nvram_read_val(MK48T59_RTC_SECONDS) != sec) {
 199               break;
 200            }
 201         }
 202
 203         /* Set the register to read the value. */
 204         ppc_md.nvram_write_val(MK48T59_RTC_CONTROLA,
 205                              (save_control | MK48T59_RTC_CA_READ));
 206
 207         sec = ppc_md.nvram_read_val(MK48T59_RTC_SECONDS);
 208         min = ppc_md.nvram_read_val(MK48T59_RTC_MINUTES);
 209         hour = ppc_md.nvram_read_val(MK48T59_RTC_HOURS);
 210         day = ppc_md.nvram_read_val(MK48T59_RTC_DAY_OF_MONTH);
 211         mon = ppc_md.nvram_read_val(MK48T59_RTC_MONTH);
 212         year = ppc_md.nvram_read_val(MK48T59_RTC_YEAR);
 213
 214         /* Let the time values change again. */
 215         ppc_md.nvram_write_val(MK48T59_RTC_CONTROLA, save_control);
 216
 217         BCD_TO_BIN(sec);
 218         BCD_TO_BIN(min);
 219         BCD_TO_BIN(hour);
 220         BCD_TO_BIN(day);
 221         BCD_TO_BIN(mon);
 222         BCD_TO_BIN(year);
 223
 224         year = year + 1900;
 225         if (year < 1970) {
 226                 year += 100;
 227         }
 228
 229         return mktime(year, mon, day, hour, min, sec);
 230 }