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         int i;
  38
  39         // check to see if the RTC makes sense.....
  40         if ((CMOS_READ(RTC_VALID) & RTC_VRT) == 0)
  41                 return mktime(1970, 1, 1, 0, 0, 0);
  42
  43         /* The Linux interpretation of the CMOS clock register contents:
  44          * When the Update-In-Progress (UIP) flag goes from 1 to 0, the
  45          * RTC registers show the second which has precisely just started.
  46          * Let's hope other operating systems interpret the RTC the same way.
  47          */
  48         /* read RTC exactly on falling edge of update flag */
  49         for (i = 0 ; i < 1000000 ; i++) /* may take up to 1 second... */
  50                 if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP)
  51                         break;
  52
  53         for (i = 0 ; i < 1000000 ; i++) /* must try at least 2.228 ms */
  54                 if (!(CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
  55                         break;
  56
  57         do { /* Isn't this overkill ? UIP above should guarantee consistency */
  58                 sec  = CMOS_READ(RTC_SECONDS);
  59                 min  = CMOS_READ(RTC_MINUTES);
  60                 hour = CMOS_READ(RTC_HOURS);
  61                 day  = CMOS_READ(RTC_DAY_OF_MONTH);
  62                 mon  = CMOS_READ(RTC_MONTH);
  63                 year = CMOS_READ(RTC_YEAR);
  64         } while (sec != CMOS_READ(RTC_SECONDS));
  65
  66         if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
  67                 BCD_TO_BIN(sec);
  68                 BCD_TO_BIN(min);
  69                 BCD_TO_BIN(hour);
  70                 BCD_TO_BIN(day);
  71                 BCD_TO_BIN(mon);
  72                 BCD_TO_BIN(year);
  73         }
  74         if ((year += 1900) < 1970)
  75                 year += 100;
  76         return mktime(year, mon, day, hour, min, sec);
  77 }
  78
  79 static int set_isa_cmos_time(void)
  80 {
  81         int retval = 0;
  82         int real_seconds, real_minutes, cmos_minutes;
  83         unsigned char save_control, save_freq_select;
  84         unsigned long nowtime = xtime.tv_sec;
  85
  86         save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being set */
  87         CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
  88
  89         save_freq_select = CMOS_READ(RTC_FREQ_SELECT); /* stop and reset prescaler */
  90         CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
  91
  92         cmos_minutes = CMOS_READ(RTC_MINUTES);
  93         if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
  94                 BCD_TO_BIN(cmos_minutes);
  95
  96         /*
  97          * since we're only adjusting minutes and seconds,
  98          * don't interfere with hour overflow. This avoids
  99          * messing with unknown time zones but requires your
 100          * RTC not to be off by more than 15 minutes
 101          */
 102         real_seconds = nowtime % 60;
 103         real_minutes = nowtime / 60;
 104         if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
 105                 real_minutes += 30;             /* correct for half hour time zone */
 106         real_minutes %= 60;
 107
 108         if (abs(real_minutes - cmos_minutes) < 30) {
 109                 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
 110                         BIN_TO_BCD(real_seconds);
 111                         BIN_TO_BCD(real_minutes);
 112                 }
 113                 CMOS_WRITE(real_seconds,RTC_SECONDS);
 114                 CMOS_WRITE(real_minutes,RTC_MINUTES);
 115         } else
 116                 retval = -1;
 117
 118         /* The following flags have to be released exactly in this order,
 119          * otherwise the DS12887 (popular MC146818A clone with integrated
 120          * battery and quartz) will not reset the oscillator and will not
 121          * update precisely 500 ms later. You won't find this mentioned in
 122          * the Dallas Semiconductor data sheets, but who believes data
 123          * sheets anyway ...                           -- Markus Kuhn
 124          */
 125         CMOS_WRITE(save_control, RTC_CONTROL);
 126         CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
 127
 128         return retval;
 129 }
 130
 131 void __init isa_rtc_init(void)
 132 {
 133         if (machine_is_co285() ||
 134             machine_is_personal_server())
 135                 /*
 136                  * Add-in 21285s shouldn't access the RTC
 137                  */
 138                 rtc_base = 0;
 139         else
 140                 rtc_base = 0x70;
 141
 142         if (rtc_base) {
 143                 int reg_d, reg_b;
 144
 145                 /*
 146                  * Probe for the RTC.
 147                  */
 148                 reg_d = CMOS_READ(RTC_REG_D);
 149
 150                 /*
 151                  * make sure the divider is set
 152                  */
 153                 CMOS_WRITE(RTC_REF_CLCK_32KHZ, RTC_REG_A);
 154
 155                 /*
 156                  * Set control reg B
 157                  *   (24 hour mode, update enabled)
 158                  */
 159                 reg_b = CMOS_READ(RTC_REG_B) & 0x7f;
 160                 reg_b |= 2;
 161                 CMOS_WRITE(reg_b, RTC_REG_B);
 162
 163                 if ((CMOS_READ(RTC_REG_A) & 0x7f) == RTC_REF_CLCK_32KHZ &&
 164                     CMOS_READ(RTC_REG_B) == reg_b) {
 165                         struct timespec tv;
 166
 167                         /*
 168                          * We have a RTC.  Check the battery
 169                          */
 170                         if ((reg_d & 0x80) == 0)
 171                                 printk(KERN_WARNING "RTC: *** warning: CMOS battery bad\n");
 172
 173                         tv.tv_nsec = 0;
 174                         tv.tv_sec = get_isa_cmos_time();
 175                         do_settimeofday(&tv);
 176                         set_rtc = set_isa_cmos_time;
 177                 } else
 178                         rtc_base = 0;
 179         }
 180 }