LXR linux/arch/arm/mach-footbridge/time.c

   1/*
   2 *  arch/arm/mach-footbridge/include/mach/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#include <linux/io.h>
  26
  27#include <mach/hardware.h>
  28
  29#include <asm/mach/time.h>
  30#include "common.h"
  31
  32static int rtc_base;
  33
  34static 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                sec = bcd2bin(sec);
  53                min = bcd2bin(min);
  54                hour = bcd2bin(hour);
  55                day = bcd2bin(day);
  56                mon = bcd2bin(mon);
  57                year = bcd2bin(year);
  58        }
  59        if ((year += 1900) < 1970)
  60                year += 100;
  61        return mktime(year, mon, day, hour, min, sec);
  62}
  63
  64static 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                cmos_minutes = bcd2bin(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                        real_seconds = bin2bcd(real_seconds);
  96                        real_minutes = bin2bcd(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
 116void __init isa_rtc_init(void)
 117{
 118        if (machine_is_personal_server())
 119                /*
 120                 * Add-in 21285s shouldn't access the RTC
 121                 */
 122                rtc_base = 0;
 123        else
 124                rtc_base = 0x70;
 125
 126        if (rtc_base) {
 127                int reg_d, reg_b;
 128
 129                /*
 130                 * Probe for the RTC.
 131                 */
 132                reg_d = CMOS_READ(RTC_REG_D);
 133
 134                /*
 135                 * make sure the divider is set
 136                 */
 137                CMOS_WRITE(RTC_REF_CLCK_32KHZ, RTC_REG_A);
 138
 139                /*
 140                 * Set control reg B
 141                 *   (24 hour mode, update enabled)
 142                 */
 143                reg_b = CMOS_READ(RTC_REG_B) & 0x7f;
 144                reg_b |= 2;
 145                CMOS_WRITE(reg_b, RTC_REG_B);
 146
 147                if ((CMOS_READ(RTC_REG_A) & 0x7f) == RTC_REF_CLCK_32KHZ &&
 148                    CMOS_READ(RTC_REG_B) == reg_b) {
 149                        struct timespec tv;
 150
 151                        /*
 152                         * We have a RTC.  Check the battery
 153                         */
 154                        if ((reg_d & 0x80) == 0)
 155                                printk(KERN_WARNING "RTC: *** warning: CMOS battery bad\n");
 156
 157                        tv.tv_nsec = 0;
 158                        tv.tv_sec = get_isa_cmos_time();
 159                        do_settimeofday(&tv);
 160                        set_rtc = set_isa_cmos_time;
 161                } else
 162                        rtc_base = 0;
 163        }
 164}
 165