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/time.h>
  19 #include <linux/timex.h>
  20 #include <linux/kernel_stat.h>
  21 #include <linux/init.h>
  22
  23 #include <asm/init.h>
  24 #include <asm/segment.h>
  25 #include <asm/io.h>
  26 #include <asm/processor.h>
  27 #include <asm/machdep.h>
  28 #include <asm/prep_nvram.h>
  29 #include <asm/mk48t59.h>
  30
  31 #include <asm/time.h>
  32
  33 /*
  34  * The motorola uses the m48t18 rtc (includes DS1643) whose registers
  35  * are at a higher end of nvram (1ff8-1fff) than the ibm mc146818
  36  * rtc (ds1386) which has regs at addr 0-d).  The intel gets
  37  * past this because the bios emulates the mc146818.
  38  *
  39  * Why in the world did they have to use different clocks?
  40  *
  41  * Right now things are hacked to check which machine we're on then
  42  * use the appropriate macro.  This is very very ugly and I should
  43  * probably have a function that checks which machine we're on then
  44  * does things correctly transparently or a function pointer which
  45  * is setup at boot time to use the correct addresses.
  46  * -- Cort
  47  */
  48
  49 /*
  50  * Set the hardware clock. -- Cort
  51  */
  52 __prep
  53 int mc146818_set_rtc_time(unsigned long nowtime)
  54 {
  55         unsigned char save_control, save_freq_select;
  56         struct rtc_time tm;
  57
  58         to_tm(nowtime, &tm);
  59
  60         /* tell the clock it's being set */
  61         save_control = CMOS_READ(RTC_CONTROL);
  62
  63         CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
  64
  65         /* stop and reset prescaler */
  66         save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
  67
  68         CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
  69
  70         tm.tm_year = (tm.tm_year - 1900) % 100;
  71         if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
  72                 BIN_TO_BCD(tm.tm_sec);
  73                 BIN_TO_BCD(tm.tm_min);
  74                 BIN_TO_BCD(tm.tm_hour);
  75                 BIN_TO_BCD(tm.tm_mon);
  76                 BIN_TO_BCD(tm.tm_mday);
  77                 BIN_TO_BCD(tm.tm_year);
  78         }
  79         CMOS_WRITE(tm.tm_sec,  RTC_SECONDS);
  80         CMOS_WRITE(tm.tm_min,  RTC_MINUTES);
  81         CMOS_WRITE(tm.tm_hour, RTC_HOURS);
  82         CMOS_WRITE(tm.tm_mon,  RTC_MONTH);
  83         CMOS_WRITE(tm.tm_mday, RTC_DAY_OF_MONTH);
  84         CMOS_WRITE(tm.tm_year, RTC_YEAR);
  85
  86         /* The following flags have to be released exactly in this order,
  87          * otherwise the DS12887 (popular MC146818A clone with integrated
  88          * battery and quartz) will not reset the oscillator and will not
  89          * update precisely 500 ms later. You won't find this mentioned in
  90          * the Dallas Semiconductor data sheets, but who believes data
  91          * sheets anyway ...                           -- Markus Kuhn
  92          */
  93         CMOS_WRITE(save_control,     RTC_CONTROL);
  94         CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
  95
  96         return 0;
  97 }
  98
  99 __prep
 100 unsigned long mc146818_get_rtc_time(void)
 101 {
 102         unsigned int year, mon, day, hour, min, sec;
 103         int uip, i;
 104
 105         /* The Linux interpretation of the CMOS clock register contents:
 106          * When the Update-In-Progress (UIP) flag goes from 1 to 0, the
 107          * RTC registers show the second which has precisely just started.
 108          * Let's hope other operating systems interpret the RTC the same way.
 109          */
 110
 111         /* Since the UIP flag is set for about 2.2 ms and the clock
 112          * is typically written with a precision of 1 jiffy, trying
 113          * to obtain a precision better than a few milliseconds is
 114          * an illusion. Only consistency is interesting, this also
 115          * allows to use the routine for /dev/rtc without a potential
 116          * 1 second kernel busy loop triggered by any reader of /dev/rtc.
 117          */
 118
 119         for ( i = 0; i<1000000; i++) {
 120                 uip = CMOS_READ(RTC_FREQ_SELECT);
 121                 sec = CMOS_READ(RTC_SECONDS);
 122                 min = CMOS_READ(RTC_MINUTES);
 123                 hour = CMOS_READ(RTC_HOURS);
 124                 day = CMOS_READ(RTC_DAY_OF_MONTH);
 125                 mon = CMOS_READ(RTC_MONTH);
 126                 year = CMOS_READ(RTC_YEAR);
 127                 uip |= CMOS_READ(RTC_FREQ_SELECT);
 128                 if ((uip & RTC_UIP)==0) break;
 129         }
 130
 131         if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)
 132             || RTC_ALWAYS_BCD)
 133         {
 134                 BCD_TO_BIN(sec);
 135                 BCD_TO_BIN(min);
 136                 BCD_TO_BIN(hour);
 137                 BCD_TO_BIN(day);
 138                 BCD_TO_BIN(mon);
 139                 BCD_TO_BIN(year);
 140         }
 141         if ((year += 1900) < 1970)
 142                 year += 100;
 143         return mktime(year, mon, day, hour, min, sec);
 144 }
 145
 146 __prep
 147 int mk48t59_set_rtc_time(unsigned long nowtime)
 148 {
 149         unsigned char save_control;
 150         struct rtc_time tm;
 151
 152
 153         to_tm(nowtime, &tm);
 154
 155         /* tell the clock it's being written */
 156         save_control = ppc_md.nvram_read_val(MK48T59_RTC_CONTROLA);
 157
 158         ppc_md.nvram_write_val(MK48T59_RTC_CONTROLA,
 159                              (save_control | MK48T59_RTC_CA_WRITE));
 160
 161         tm.tm_year = (tm.tm_year - 1900) % 100;
 162         BIN_TO_BCD(tm.tm_sec);
 163         BIN_TO_BCD(tm.tm_min);
 164         BIN_TO_BCD(tm.tm_hour);
 165         BIN_TO_BCD(tm.tm_mon);
 166         BIN_TO_BCD(tm.tm_mday);
 167         BIN_TO_BCD(tm.tm_year);
 168
 169         ppc_md.nvram_write_val(MK48T59_RTC_SECONDS,      tm.tm_sec);
 170         ppc_md.nvram_write_val(MK48T59_RTC_MINUTES,      tm.tm_min);
 171         ppc_md.nvram_write_val(MK48T59_RTC_HOURS,        tm.tm_hour);
 172         ppc_md.nvram_write_val(MK48T59_RTC_MONTH,        tm.tm_mon);
 173         ppc_md.nvram_write_val(MK48T59_RTC_DAY_OF_MONTH, tm.tm_mday);
 174         ppc_md.nvram_write_val(MK48T59_RTC_YEAR,         tm.tm_year);
 175
 176         /* Turn off the write bit. */
 177         ppc_md.nvram_write_val(MK48T59_RTC_CONTROLA, save_control);
 178
 179         return 0;
 180 }
 181
 182 __prep
 183 unsigned long mk48t59_get_rtc_time(void)
 184 {
 185         unsigned char save_control;
 186         unsigned int year, mon, day, hour, min, sec;
 187
 188         /* Simple: freeze the clock, read it and allow updates again */
 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         /* Set the register to read the value. */
 194         ppc_md.nvram_write_val(MK48T59_RTC_CONTROLA,
 195                              (save_control | MK48T59_RTC_CA_READ));
 196
 197         sec = ppc_md.nvram_read_val(MK48T59_RTC_SECONDS);
 198         min = ppc_md.nvram_read_val(MK48T59_RTC_MINUTES);
 199         hour = ppc_md.nvram_read_val(MK48T59_RTC_HOURS);
 200         day = ppc_md.nvram_read_val(MK48T59_RTC_DAY_OF_MONTH);
 201         mon = ppc_md.nvram_read_val(MK48T59_RTC_MONTH);
 202         year = ppc_md.nvram_read_val(MK48T59_RTC_YEAR);
 203
 204         /* Let the time values change again. */
 205         ppc_md.nvram_write_val(MK48T59_RTC_CONTROLA, save_control);
 206
 207         BCD_TO_BIN(sec);
 208         BCD_TO_BIN(min);
 209         BCD_TO_BIN(hour);
 210         BCD_TO_BIN(day);
 211         BCD_TO_BIN(mon);
 212         BCD_TO_BIN(year);
 213
 214         year = year + 1900;
 215         if (year < 1970) {
 216                 year += 100;
 217         }
 218
 219         return mktime(year, mon, day, hour, min, sec);
 220 }