arch/ppc/platforms/chrp_time.c

   1 /*
   2  *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
   3  *
   4  * Adapted for PowerPC (PReP) by Gary Thomas
   5  * Modified by Cort Dougan (cort@cs.nmt.edu).
   6  * Copied and modified from arch/i386/kernel/time.c
   7  *
   8  */
   9 #include <linux/errno.h>
  10 #include <linux/sched.h>
  11 #include <linux/kernel.h>
  12 #include <linux/param.h>
  13 #include <linux/string.h>
  14 #include <linux/mm.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/time.h>
  17 #include <linux/timex.h>
  18 #include <linux/kernel_stat.h>
  19 #include <linux/mc146818rtc.h>
  20 #include <linux/init.h>
  21 #include <linux/bcd.h>
  22
  23 #include <asm/io.h>
  24 #include <asm/nvram.h>
  25 #include <asm/prom.h>
  26 #include <asm/sections.h>
  27 #include <asm/time.h>
  28
  29 extern spinlock_t rtc_lock;
  30
  31 static int nvram_as1 = NVRAM_AS1;
  32 static int nvram_as0 = NVRAM_AS0;
  33 static int nvram_data = NVRAM_DATA;
  34
  35 long __init chrp_time_init(void)
  36 {
  37         struct device_node *rtcs;
  38         int base;
  39
  40         rtcs = find_compatible_devices("rtc", "pnpPNP,b00");
  41         if (rtcs == NULL)
  42                 rtcs = find_compatible_devices("rtc", "ds1385-rtc");
  43         if (rtcs == NULL || rtcs->addrs == NULL)
  44                 return 0;
  45         base = rtcs->addrs[0].address;
  46         nvram_as1 = 0;
  47         nvram_as0 = base;
  48         nvram_data = base + 1;
  49
  50         return 0;
  51 }
  52
  53 int chrp_cmos_clock_read(int addr)
  54 {
  55         if (nvram_as1 != 0)
  56                 outb(addr>>8, nvram_as1);
  57         outb(addr, nvram_as0);
  58         return (inb(nvram_data));
  59 }
  60
  61 void chrp_cmos_clock_write(unsigned long val, int addr)
  62 {
  63         if (nvram_as1 != 0)
  64                 outb(addr>>8, nvram_as1);
  65         outb(addr, nvram_as0);
  66         outb(val, nvram_data);
  67         return;
  68 }
  69
  70 /*
  71  * Set the hardware clock. -- Cort
  72  */
  73 int chrp_set_rtc_time(unsigned long nowtime)
  74 {
  75         unsigned char save_control, save_freq_select;
  76         struct rtc_time tm;
  77
  78         spin_lock(&rtc_lock);
  79         to_tm(nowtime, &tm);
  80
  81         save_control = chrp_cmos_clock_read(RTC_CONTROL); /* tell the clock it's being set */
  82
  83         chrp_cmos_clock_write((save_control|RTC_SET), RTC_CONTROL);
  84
  85         save_freq_select = chrp_cmos_clock_read(RTC_FREQ_SELECT); /* stop and reset prescaler */
  86
  87         chrp_cmos_clock_write((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
  88
  89         tm.tm_year -= 1900;
  90         if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
  91                 BIN_TO_BCD(tm.tm_sec);
  92                 BIN_TO_BCD(tm.tm_min);
  93                 BIN_TO_BCD(tm.tm_hour);
  94                 BIN_TO_BCD(tm.tm_mon);
  95                 BIN_TO_BCD(tm.tm_mday);
  96                 BIN_TO_BCD(tm.tm_year);
  97         }
  98         chrp_cmos_clock_write(tm.tm_sec,RTC_SECONDS);
  99         chrp_cmos_clock_write(tm.tm_min,RTC_MINUTES);
 100         chrp_cmos_clock_write(tm.tm_hour,RTC_HOURS);
 101         chrp_cmos_clock_write(tm.tm_mon,RTC_MONTH);
 102         chrp_cmos_clock_write(tm.tm_mday,RTC_DAY_OF_MONTH);
 103         chrp_cmos_clock_write(tm.tm_year,RTC_YEAR);
 104
 105         /* The following flags have to be released exactly in this order,
 106          * otherwise the DS12887 (popular MC146818A clone with integrated
 107          * battery and quartz) will not reset the oscillator and will not
 108          * update precisely 500 ms later. You won't find this mentioned in
 109          * the Dallas Semiconductor data sheets, but who believes data
 110          * sheets anyway ...                           -- Markus Kuhn
 111          */
 112         chrp_cmos_clock_write(save_control, RTC_CONTROL);
 113         chrp_cmos_clock_write(save_freq_select, RTC_FREQ_SELECT);
 114
 115         spin_unlock(&rtc_lock);
 116         return 0;
 117 }
 118
 119 unsigned long chrp_get_rtc_time(void)
 120 {
 121         unsigned int year, mon, day, hour, min, sec;
 122
 123         do {
 124                 sec = chrp_cmos_clock_read(RTC_SECONDS);
 125                 min = chrp_cmos_clock_read(RTC_MINUTES);
 126                 hour = chrp_cmos_clock_read(RTC_HOURS);
 127                 day = chrp_cmos_clock_read(RTC_DAY_OF_MONTH);
 128                 mon = chrp_cmos_clock_read(RTC_MONTH);
 129                 year = chrp_cmos_clock_read(RTC_YEAR);
 130         } while (sec != chrp_cmos_clock_read(RTC_SECONDS));
 131
 132         if (!(chrp_cmos_clock_read(RTC_CONTROL) & RTC_DM_BINARY)
 133             || RTC_ALWAYS_BCD) {
 134                 BCD_TO_BIN(sec);
 135                 BCD_TO_BIN(min);
 136                 BCD_TO_BIN(hour);
 137                 BCD_TO_BIN(day);
 138                 BCD_TO_BIN(mon);
 139                 BCD_TO_BIN(year);
 140         }
 141
 142         year += 1900;
 143         if (year < 1970)
 144                 year += 100;
 145         return mktime(year, mon, day, hour, min, sec);
 146 }
 147
 148 /*
 149  * Calibrate the decrementer frequency with the VIA timer 1.
 150  */
 151 #define VIA_TIMER_FREQ_6        4700000 /* time 1 frequency * 6 */
 152
 153 /* VIA registers */
 154 #define RS              0x200           /* skip between registers */
 155 #define T1CL            (4*RS)          /* Timer 1 ctr/latch (low 8 bits) */
 156 #define T1CH            (5*RS)          /* Timer 1 counter (high 8 bits) */
 157 #define T1LL            (6*RS)          /* Timer 1 latch (low 8 bits) */
 158 #define T1LH            (7*RS)          /* Timer 1 latch (high 8 bits) */
 159 #define ACR             (11*RS)         /* Auxiliary control register */
 160 #define IFR             (13*RS)         /* Interrupt flag register */
 161
 162 /* Bits in ACR */
 163 #define T1MODE          0xc0            /* Timer 1 mode */
 164 #define T1MODE_CONT     0x40            /*  continuous interrupts */
 165
 166 /* Bits in IFR and IER */
 167 #define T1_INT          0x40            /* Timer 1 interrupt */
 168
 169 static int __init chrp_via_calibrate_decr(void)
 170 {
 171         struct device_node *vias;
 172         volatile unsigned char __iomem *via;
 173         int count = VIA_TIMER_FREQ_6 / 100;
 174         unsigned int dstart, dend;
 175
 176         vias = find_devices("via-cuda");
 177         if (vias == 0)
 178                 vias = find_devices("via");
 179         if (vias == 0 || vias->n_addrs == 0)
 180                 return 0;
 181         via = ioremap(vias->addrs[0].address, vias->addrs[0].size);
 182
 183         /* set timer 1 for continuous interrupts */
 184         out_8(&via[ACR], (via[ACR] & ~T1MODE) | T1MODE_CONT);
 185         /* set the counter to a small value */
 186         out_8(&via[T1CH], 2);
 187         /* set the latch to `count' */
 188         out_8(&via[T1LL], count);
 189         out_8(&via[T1LH], count >> 8);
 190         /* wait until it hits 0 */
 191         while ((in_8(&via[IFR]) & T1_INT) == 0)
 192                 ;
 193         dstart = get_dec();
 194         /* clear the interrupt & wait until it hits 0 again */
 195         in_8(&via[T1CL]);
 196         while ((in_8(&via[IFR]) & T1_INT) == 0)
 197                 ;
 198         dend = get_dec();
 199
 200         tb_ticks_per_jiffy = (dstart - dend) / ((6 * HZ)/100);
 201         tb_to_us = mulhwu_scale_factor(dstart - dend, 60000);
 202
 203         printk(KERN_INFO "via_calibrate_decr: ticks per jiffy = %u (%u ticks)\n",
 204                tb_ticks_per_jiffy, dstart - dend);
 205
 206         iounmap(via);
 207
 208         return 1;
 209 }
 210
 211 void __init chrp_calibrate_decr(void)
 212 {
 213         struct device_node *cpu;
 214         unsigned int freq, *fp;
 215
 216         if (chrp_via_calibrate_decr())
 217                 return;
 218
 219         /*
 220          * The cpu node should have a timebase-frequency property
 221          * to tell us the rate at which the decrementer counts.
 222          */
 223         freq = 16666000;                /* hardcoded default */
 224         cpu = find_type_devices("cpu");
 225         if (cpu != 0) {
 226                 fp = (unsigned int *)
 227                         get_property(cpu, "timebase-frequency", NULL);
 228                 if (fp != 0)
 229                         freq = *fp;
 230         }
 231         printk("time_init: decrementer frequency = %u.%.6u MHz\n",
 232                freq/1000000, freq%1000000);
 233         tb_ticks_per_jiffy = freq / HZ;
 234         tb_to_us = mulhwu_scale_factor(freq, 1000000);
 235 }