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 setup_default_decr(void);
  46 extern void GregorianDay(struct rtc_time * tm);
  47
  48 extern unsigned long ppc_tb_freq;
  49 extern unsigned long ppc_proc_freq;
  50 static int maple_rtc_addr;
  51
  52 static int maple_clock_read(int addr)
  53 {
  54         outb_p(addr, maple_rtc_addr);
  55         return inb_p(maple_rtc_addr+1);
  56 }
  57
  58 static void maple_clock_write(unsigned long val, int addr)
  59 {
  60         outb_p(addr, maple_rtc_addr);
  61         outb_p(val, maple_rtc_addr+1);
  62 }
  63
  64 void maple_get_rtc_time(struct rtc_time *tm)
  65 {
  66         int uip, i;
  67
  68         /* The Linux interpretation of the CMOS clock register contents:
  69          * When the Update-In-Progress (UIP) flag goes from 1 to 0, the
  70          * RTC registers show the second which has precisely just started.
  71          * Let's hope other operating systems interpret the RTC the same way.
  72          */
  73
  74         /* Since the UIP flag is set for about 2.2 ms and the clock
  75          * is typically written with a precision of 1 jiffy, trying
  76          * to obtain a precision better than a few milliseconds is
  77          * an illusion. Only consistency is interesting, this also
  78          * allows to use the routine for /dev/rtc without a potential
  79          * 1 second kernel busy loop triggered by any reader of /dev/rtc.
  80          */
  81
  82         for (i = 0; i<1000000; i++) {
  83                 uip = maple_clock_read(RTC_FREQ_SELECT);
  84                 tm->tm_sec = maple_clock_read(RTC_SECONDS);
  85                 tm->tm_min = maple_clock_read(RTC_MINUTES);
  86                 tm->tm_hour = maple_clock_read(RTC_HOURS);
  87                 tm->tm_mday = maple_clock_read(RTC_DAY_OF_MONTH);
  88                 tm->tm_mon = maple_clock_read(RTC_MONTH);
  89                 tm->tm_year = maple_clock_read(RTC_YEAR);
  90                 uip |= maple_clock_read(RTC_FREQ_SELECT);
  91                 if ((uip & RTC_UIP)==0)
  92                         break;
  93         }
  94
  95         if (!(maple_clock_read(RTC_CONTROL) & RTC_DM_BINARY)
  96             || RTC_ALWAYS_BCD) {
  97                 BCD_TO_BIN(tm->tm_sec);
  98                 BCD_TO_BIN(tm->tm_min);
  99                 BCD_TO_BIN(tm->tm_hour);
 100                 BCD_TO_BIN(tm->tm_mday);
 101                 BCD_TO_BIN(tm->tm_mon);
 102                 BCD_TO_BIN(tm->tm_year);
 103           }
 104         if ((tm->tm_year + 1900) < 1970)
 105                 tm->tm_year += 100;
 106
 107         GregorianDay(tm);
 108 }
 109
 110 int maple_set_rtc_time(struct rtc_time *tm)
 111 {
 112         unsigned char save_control, save_freq_select;
 113         int sec, min, hour, mon, mday, year;
 114
 115         spin_lock(&rtc_lock);
 116
 117         save_control = maple_clock_read(RTC_CONTROL); /* tell the clock it's being set */
 118
 119         maple_clock_write((save_control|RTC_SET), RTC_CONTROL);
 120
 121         save_freq_select = maple_clock_read(RTC_FREQ_SELECT); /* stop and reset prescaler */
 122
 123         maple_clock_write((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
 124
 125         sec = tm->tm_sec;
 126         min = tm->tm_min;
 127         hour = tm->tm_hour;
 128         mon = tm->tm_mon;
 129         mday = tm->tm_mday;
 130         year = tm->tm_year;
 131
 132         if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
 133                 BIN_TO_BCD(sec);
 134                 BIN_TO_BCD(min);
 135                 BIN_TO_BCD(hour);
 136                 BIN_TO_BCD(mon);
 137                 BIN_TO_BCD(mday);
 138                 BIN_TO_BCD(year);
 139         }
 140         maple_clock_write(sec, RTC_SECONDS);
 141         maple_clock_write(min, RTC_MINUTES);
 142         maple_clock_write(hour, RTC_HOURS);
 143         maple_clock_write(mon, RTC_MONTH);
 144         maple_clock_write(mday, RTC_DAY_OF_MONTH);
 145         maple_clock_write(year, RTC_YEAR);
 146
 147         /* The following flags have to be released exactly in this order,
 148          * otherwise the DS12887 (popular MC146818A clone with integrated
 149          * battery and quartz) will not reset the oscillator and will not
 150          * update precisely 500 ms later. You won't find this mentioned in
 151          * the Dallas Semiconductor data sheets, but who believes data
 152          * sheets anyway ...                           -- Markus Kuhn
 153          */
 154         maple_clock_write(save_control, RTC_CONTROL);
 155         maple_clock_write(save_freq_select, RTC_FREQ_SELECT);
 156
 157         spin_unlock(&rtc_lock);
 158
 159         return 0;
 160 }
 161
 162 void __init maple_get_boot_time(struct rtc_time *tm)
 163 {
 164         struct device_node *rtcs;
 165
 166         rtcs = find_compatible_devices("rtc", "pnpPNP,b00");
 167         if (rtcs && rtcs->addrs) {
 168                 maple_rtc_addr = rtcs->addrs[0].address;
 169                 printk(KERN_INFO "Maple: Found RTC at 0x%x\n", maple_rtc_addr);
 170         } else {
 171                 maple_rtc_addr = RTC_PORT(0); /* legacy address */
 172                 printk(KERN_INFO "Maple: No device node for RTC, assuming "
 173                        "legacy address (0x%x)\n", maple_rtc_addr);
 174         }
 175
 176         maple_get_rtc_time(tm);
 177 }
 178
 179 /* XXX FIXME: Some sane defaults: 125 MHz timebase, 1GHz processor */
 180 #define DEFAULT_TB_FREQ         125000000UL
 181 #define DEFAULT_PROC_FREQ       (DEFAULT_TB_FREQ * 8)
 182
 183 void __init maple_calibrate_decr(void)
 184 {
 185         struct device_node *cpu;
 186         struct div_result divres;
 187         unsigned int *fp = NULL;
 188
 189         /*
 190          * The cpu node should have a timebase-frequency property
 191          * to tell us the rate at which the decrementer counts.
 192          */
 193         cpu = of_find_node_by_type(NULL, "cpu");
 194
 195         ppc_tb_freq = DEFAULT_TB_FREQ;
 196         if (cpu != 0)
 197                 fp = (unsigned int *)get_property(cpu, "timebase-frequency", NULL);
 198         if (fp != NULL)
 199                 ppc_tb_freq = *fp;
 200         else
 201                 printk(KERN_ERR "WARNING: Estimating decrementer frequency (not found)\n");
 202         fp = NULL;
 203         ppc_proc_freq = DEFAULT_PROC_FREQ;
 204         if (cpu != 0)
 205                 fp = (unsigned int *)get_property(cpu, "clock-frequency", NULL);
 206         if (fp != NULL)
 207                 ppc_proc_freq = *fp;
 208         else
 209                 printk(KERN_ERR "WARNING: Estimating processor frequency (not found)\n");
 210
 211         of_node_put(cpu);
 212
 213         printk(KERN_INFO "time_init: decrementer frequency = %lu.%.6lu MHz\n",
 214                ppc_tb_freq/1000000, ppc_tb_freq%1000000);
 215         printk(KERN_INFO "time_init: processor frequency   = %lu.%.6lu MHz\n",
 216                ppc_proc_freq/1000000, ppc_proc_freq%1000000);
 217
 218         tb_ticks_per_jiffy = ppc_tb_freq / HZ;
 219         tb_ticks_per_sec = tb_ticks_per_jiffy * HZ;
 220         tb_ticks_per_usec = ppc_tb_freq / 1000000;
 221         tb_to_us = mulhwu_scale_factor(ppc_tb_freq, 1000000);
 222         div128_by_32(1024*1024, 0, tb_ticks_per_sec, &divres);
 223         tb_to_xs = divres.result_low;
 224
 225         setup_default_decr();
 226 }