arch/ppc64/kernel/maple_time.c

   1 /*
   2  *  arch/ppc64/kernel/maple_time.c
   3  *
   4  *  (c) Copyright 2004 Benjamin Herrenschmidt (benh@kernel.crashing.org),
   5  *                     IBM Corp.
   6  *
   7  *  This program is free software; you can redistribute it and/or
   8  *  modify it under the terms of the GNU General Public License
   9  *  as published by the Free Software Foundation; either version
  10  *  2 of the License, or (at your option) any later version.
  11  *
  12  */
  13
  14 #undef DEBUG
  15
  16 #include <linux/config.h>
  17 #include <linux/errno.h>
  18 #include <linux/sched.h>
  19 #include <linux/kernel.h>
  20 #include <linux/param.h>
  21 #include <linux/string.h>
  22 #include <linux/mm.h>
  23 #include <linux/init.h>
  24 #include <linux/time.h>
  25 #include <linux/adb.h>
  26 #include <linux/pmu.h>
  27 #include <linux/interrupt.h>
  28 #include <linux/mc146818rtc.h>
  29 #include <linux/bcd.h>
  30
  31 #include <asm/sections.h>
  32 #include <asm/prom.h>
  33 #include <asm/system.h>
  34 #include <asm/io.h>
  35 #include <asm/pgtable.h>
  36 #include <asm/machdep.h>
  37 #include <asm/time.h>
  38
  39 #ifdef DEBUG
  40 #define DBG(x...) printk(x)
  41 #else
  42 #define DBG(x...)
  43 #endif
  44
  45 extern void GregorianDay(struct rtc_time * tm);
  46
  47 static int maple_rtc_addr;
  48
  49 static int maple_clock_read(int addr)
  50 {
  51         outb_p(addr, maple_rtc_addr);
  52         return inb_p(maple_rtc_addr+1);
  53 }
  54
  55 static void maple_clock_write(unsigned long val, int addr)
  56 {
  57         outb_p(addr, maple_rtc_addr);
  58         outb_p(val, maple_rtc_addr+1);
  59 }
  60
  61 void maple_get_rtc_time(struct rtc_time *tm)
  62 {
  63         int uip, i;
  64
  65         /* The Linux interpretation of the CMOS clock register contents:
  66          * When the Update-In-Progress (UIP) flag goes from 1 to 0, the
  67          * RTC registers show the second which has precisely just started.
  68          * Let's hope other operating systems interpret the RTC the same way.
  69          */
  70
  71         /* Since the UIP flag is set for about 2.2 ms and the clock
  72          * is typically written with a precision of 1 jiffy, trying
  73          * to obtain a precision better than a few milliseconds is
  74          * an illusion. Only consistency is interesting, this also
  75          * allows to use the routine for /dev/rtc without a potential
  76          * 1 second kernel busy loop triggered by any reader of /dev/rtc.
  77          */
  78
  79         for (i = 0; i<1000000; i++) {
  80                 uip = maple_clock_read(RTC_FREQ_SELECT);
  81                 tm->tm_sec = maple_clock_read(RTC_SECONDS);
  82                 tm->tm_min = maple_clock_read(RTC_MINUTES);
  83                 tm->tm_hour = maple_clock_read(RTC_HOURS);
  84                 tm->tm_mday = maple_clock_read(RTC_DAY_OF_MONTH);
  85                 tm->tm_mon = maple_clock_read(RTC_MONTH);
  86                 tm->tm_year = maple_clock_read(RTC_YEAR);
  87                 uip |= maple_clock_read(RTC_FREQ_SELECT);
  88                 if ((uip & RTC_UIP)==0)
  89                         break;
  90         }
  91
  92         if (!(maple_clock_read(RTC_CONTROL) & RTC_DM_BINARY)
  93             || RTC_ALWAYS_BCD) {
  94                 BCD_TO_BIN(tm->tm_sec);
  95                 BCD_TO_BIN(tm->tm_min);
  96                 BCD_TO_BIN(tm->tm_hour);
  97                 BCD_TO_BIN(tm->tm_mday);
  98                 BCD_TO_BIN(tm->tm_mon);
  99                 BCD_TO_BIN(tm->tm_year);
 100           }
 101         if ((tm->tm_year + 1900) < 1970)
 102                 tm->tm_year += 100;
 103
 104         GregorianDay(tm);
 105 }
 106
 107 int maple_set_rtc_time(struct rtc_time *tm)
 108 {
 109         unsigned char save_control, save_freq_select;
 110         int sec, min, hour, mon, mday, year;
 111
 112         spin_lock(&rtc_lock);
 113
 114         save_control = maple_clock_read(RTC_CONTROL); /* tell the clock it's being set */
 115
 116         maple_clock_write((save_control|RTC_SET), RTC_CONTROL);
 117
 118         save_freq_select = maple_clock_read(RTC_FREQ_SELECT); /* stop and reset prescaler */
 119
 120         maple_clock_write((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
 121
 122         sec = tm->tm_sec;
 123         min = tm->tm_min;
 124         hour = tm->tm_hour;
 125         mon = tm->tm_mon;
 126         mday = tm->tm_mday;
 127         year = tm->tm_year;
 128
 129         if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
 130                 BIN_TO_BCD(sec);
 131                 BIN_TO_BCD(min);
 132                 BIN_TO_BCD(hour);
 133                 BIN_TO_BCD(mon);
 134                 BIN_TO_BCD(mday);
 135                 BIN_TO_BCD(year);
 136         }
 137         maple_clock_write(sec, RTC_SECONDS);
 138         maple_clock_write(min, RTC_MINUTES);
 139         maple_clock_write(hour, RTC_HOURS);
 140         maple_clock_write(mon, RTC_MONTH);
 141         maple_clock_write(mday, RTC_DAY_OF_MONTH);
 142         maple_clock_write(year, RTC_YEAR);
 143
 144         /* The following flags have to be released exactly in this order,
 145          * otherwise the DS12887 (popular MC146818A clone with integrated
 146          * battery and quartz) will not reset the oscillator and will not
 147          * update precisely 500 ms later. You won't find this mentioned in
 148          * the Dallas Semiconductor data sheets, but who believes data
 149          * sheets anyway ...                           -- Markus Kuhn
 150          */
 151         maple_clock_write(save_control, RTC_CONTROL);
 152         maple_clock_write(save_freq_select, RTC_FREQ_SELECT);
 153
 154         spin_unlock(&rtc_lock);
 155
 156         return 0;
 157 }
 158
 159 void __init maple_get_boot_time(struct rtc_time *tm)
 160 {
 161         struct device_node *rtcs;
 162
 163         rtcs = find_compatible_devices("rtc", "pnpPNP,b00");
 164         if (rtcs && rtcs->addrs) {
 165                 maple_rtc_addr = rtcs->addrs[0].address;
 166                 printk(KERN_INFO "Maple: Found RTC at 0x%x\n", maple_rtc_addr);
 167         } else {
 168                 maple_rtc_addr = RTC_PORT(0); /* legacy address */
 169                 printk(KERN_INFO "Maple: No device node for RTC, assuming "
 170                        "legacy address (0x%x)\n", maple_rtc_addr);
 171         }
 172
 173         maple_get_rtc_time(tm);
 174 }
 175