arch/arm/mach-footbridge/time.c

   1 /*
   2  *  linux/include/asm-arm/arch-ebsa285/time.h
   3  *
   4  *  Copyright (C) 1998 Russell King.
   5  *  Copyright (C) 1998 Phil Blundell
   6  *
   7  * CATS has a real-time clock, though the evaluation board doesn't.
   8  *
   9  * Changelog:
  10  *  21-Mar-1998 RMK     Created
  11  *  27-Aug-1998 PJB     CATS support
  12  *  28-Dec-1998 APH     Made leds optional
  13  *  20-Jan-1999 RMK     Started merge of EBSA285, CATS and NetWinder
  14  *  16-Mar-1999 RMK     More support for EBSA285-like machines with RTCs in
  15  */
  16
  17 #define RTC_PORT(x)             (rtc_base+(x))
  18 #define RTC_ALWAYS_BCD          0
  19
  20 #include <linux/timex.h>
  21 #include <linux/init.h>
  22 #include <linux/sched.h>
  23 #include <linux/mc146818rtc.h>
  24 #include <linux/bcd.h>
  25
  26 #include <asm/hardware.h>
  27 #include <asm/io.h>
  28
  29 #include <asm/mach/time.h>
  30 #include "common.h"
  31
  32 static int rtc_base;
  33
  34 static unsigned long __init get_isa_cmos_time(void)
  35 {
  36         unsigned int year, mon, day, hour, min, sec;
  37
  38         // check to see if the RTC makes sense.....
  39         if ((CMOS_READ(RTC_VALID) & RTC_VRT) == 0)
  40                 return mktime(1970, 1, 1, 0, 0, 0);
  41
  42         do {
  43                 sec  = CMOS_READ(RTC_SECONDS);
  44                 min  = CMOS_READ(RTC_MINUTES);
  45                 hour = CMOS_READ(RTC_HOURS);
  46                 day  = CMOS_READ(RTC_DAY_OF_MONTH);
  47                 mon  = CMOS_READ(RTC_MONTH);
  48                 year = CMOS_READ(RTC_YEAR);
  49         } while (sec != CMOS_READ(RTC_SECONDS));
  50
  51         if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
  52                 BCD_TO_BIN(sec);
  53                 BCD_TO_BIN(min);
  54                 BCD_TO_BIN(hour);
  55                 BCD_TO_BIN(day);
  56                 BCD_TO_BIN(mon);
  57                 BCD_TO_BIN(year);
  58         }
  59         if ((year += 1900) < 1970)
  60                 year += 100;
  61         return mktime(year, mon, day, hour, min, sec);
  62 }
  63
  64 static int set_isa_cmos_time(void)
  65 {
  66         int retval = 0;
  67         int real_seconds, real_minutes, cmos_minutes;
  68         unsigned char save_control, save_freq_select;
  69         unsigned long nowtime = xtime.tv_sec;
  70
  71         save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being set */
  72         CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
  73
  74         save_freq_select = CMOS_READ(RTC_FREQ_SELECT); /* stop and reset prescaler */
  75         CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
  76
  77         cmos_minutes = CMOS_READ(RTC_MINUTES);
  78         if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
  79                 BCD_TO_BIN(cmos_minutes);
  80
  81         /*
  82          * since we're only adjusting minutes and seconds,
  83          * don't interfere with hour overflow. This avoids
  84          * messing with unknown time zones but requires your
  85          * RTC not to be off by more than 15 minutes
  86          */
  87         real_seconds = nowtime % 60;
  88         real_minutes = nowtime / 60;
  89         if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
  90                 real_minutes += 30;             /* correct for half hour time zone */
  91         real_minutes %= 60;
  92
  93         if (abs(real_minutes - cmos_minutes) < 30) {
  94                 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
  95                         BIN_TO_BCD(real_seconds);
  96                         BIN_TO_BCD(real_minutes);
  97                 }
  98                 CMOS_WRITE(real_seconds,RTC_SECONDS);
  99                 CMOS_WRITE(real_minutes,RTC_MINUTES);
 100         } else
 101                 retval = -1;
 102
 103         /* The following flags have to be released exactly in this order,
 104          * otherwise the DS12887 (popular MC146818A clone with integrated
 105          * battery and quartz) will not reset the oscillator and will not
 106          * update precisely 500 ms later. You won't find this mentioned in
 107          * the Dallas Semiconductor data sheets, but who believes data
 108          * sheets anyway ...                           -- Markus Kuhn
 109          */
 110         CMOS_WRITE(save_control, RTC_CONTROL);
 111         CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
 112
 113         return retval;
 114 }
 115
 116 void __init isa_rtc_init(void)
 117 {
 118         if (machine_is_co285() ||
 119             machine_is_personal_server())
 120                 /*
 121                  * Add-in 21285s shouldn't access the RTC
 122                  */
 123                 rtc_base = 0;
 124         else
 125                 rtc_base = 0x70;
 126
 127         if (rtc_base) {
 128                 int reg_d, reg_b;
 129
 130                 /*
 131                  * Probe for the RTC.
 132                  */
 133                 reg_d = CMOS_READ(RTC_REG_D);
 134
 135                 /*
 136                  * make sure the divider is set
 137                  */
 138                 CMOS_WRITE(RTC_REF_CLCK_32KHZ, RTC_REG_A);
 139
 140                 /*
 141                  * Set control reg B
 142                  *   (24 hour mode, update enabled)
 143                  */
 144                 reg_b = CMOS_READ(RTC_REG_B) & 0x7f;
 145                 reg_b |= 2;
 146                 CMOS_WRITE(reg_b, RTC_REG_B);
 147
 148                 if ((CMOS_READ(RTC_REG_A) & 0x7f) == RTC_REF_CLCK_32KHZ &&
 149                     CMOS_READ(RTC_REG_B) == reg_b) {
 150                         struct timespec tv;
 151
 152                         /*
 153                          * We have a RTC.  Check the battery
 154                          */
 155                         if ((reg_d & 0x80) == 0)
 156                                 printk(KERN_WARNING "RTC: *** warning: CMOS battery bad\n");
 157
 158                         tv.tv_nsec = 0;
 159                         tv.tv_sec = get_isa_cmos_time();
 160                         do_settimeofday(&tv);
 161                         set_rtc = set_isa_cmos_time;
 162                 } else
 163                         rtc_base = 0;
 164         }
 165 }