arch/mips/ddb5xxx/common/rtc_ds1386.c

   1 /*
   2  * Copyright 2001 MontaVista Software Inc.
   3  * Author: jsun@mvista.com or jsun@junsun.net
   4  *
   5  * arch/mips/ddb5xxx/common/rtc_ds1386.c
   6  *     low-level RTC hookups for s for Dallas 1396 chip.
   7  *
   8  * This program is free software; you can redistribute  it and/or modify it
   9  * under  the terms of  the GNU General  Public License as published by the
  10  * Free Software Foundation;  either version 2 of the  License, or (at your
  11  * option) any later version.
  12  */
  13
  14
  15 /*
  16  * This file exports a function, rtc_ds1386_init(), which expects an
  17  * uncached base address as the argument.  It will set the two function
  18  * pointers expected by the MIPS generic timer code.
  19  */
  20
  21 #include <linux/types.h>
  22 #include <linux/time.h>
  23 #include <linux/bcd.h>
  24
  25 #include <asm/time.h>
  26 #include <asm/addrspace.h>
  27
  28 #include <asm/mc146818rtc.h>
  29 #include <asm/debug.h>
  30
  31 #define EPOCH           2000
  32
  33 #define READ_RTC(x)     *(volatile unsigned char*)(rtc_base+x)
  34 #define WRITE_RTC(x, y) *(volatile unsigned char*)(rtc_base+x) = y
  35
  36 static unsigned long rtc_base;
  37
  38 static unsigned long
  39 rtc_ds1386_get_time(void)
  40 {
  41         u8 byte;
  42         u8 temp;
  43         unsigned int year, month, day, hour, minute, second;
  44         unsigned long flags;
  45
  46         spin_lock_irqsave(&rtc_lock, flags);
  47         /* let us freeze external registers */
  48         byte = READ_RTC(0xB);
  49         byte &= 0x3f;
  50         WRITE_RTC(0xB, byte);
  51
  52         /* read time data */
  53         year = BCD2BIN(READ_RTC(0xA)) + EPOCH;
  54         month = BCD2BIN(READ_RTC(0x9) & 0x1f);
  55         day = BCD2BIN(READ_RTC(0x8));
  56         minute = BCD2BIN(READ_RTC(0x2));
  57         second = BCD2BIN(READ_RTC(0x1));
  58
  59         /* hour is special - deal with it later */
  60         temp = READ_RTC(0x4);
  61
  62         /* enable time transfer */
  63         byte |= 0x80;
  64         WRITE_RTC(0xB, byte);
  65         spin_unlock_irqrestore(&rtc_lock, flags);
  66
  67         /* calc hour */
  68         if (temp & 0x40) {
  69                 /* 12 hour format */
  70                 hour = BCD2BIN(temp & 0x1f);
  71                 if (temp & 0x20) hour += 12;            /* PM */
  72         } else {
  73                 /* 24 hour format */
  74                 hour = BCD2BIN(temp & 0x3f);
  75         }
  76
  77         return mktime(year, month, day, hour, minute, second);
  78 }
  79
  80 static int
  81 rtc_ds1386_set_time(unsigned long t)
  82 {
  83         struct rtc_time tm;
  84         u8 byte;
  85         u8 temp;
  86         u8 year, month, day, hour, minute, second;
  87         unsigned long flags;
  88
  89         spin_lock_irqsave(&rtc_lock, flags);
  90         /* let us freeze external registers */
  91         byte = READ_RTC(0xB);
  92         byte &= 0x3f;
  93         WRITE_RTC(0xB, byte);
  94
  95         /* convert */
  96         to_tm(t, &tm);
  97
  98
  99         /* check each field one by one */
 100         year = BIN2BCD(tm.tm_year - EPOCH);
 101         if (year != READ_RTC(0xA)) {
 102                 WRITE_RTC(0xA, year);
 103         }
 104
 105         temp = READ_RTC(0x9);
 106         month = BIN2BCD(tm.tm_mon+1);   /* tm_mon starts from 0 to 11 */
 107         if (month != (temp & 0x1f)) {
 108                 WRITE_RTC( 0x9,
 109                            (month & 0x1f) | (temp & ~0x1f) );
 110         }
 111
 112         day = BIN2BCD(tm.tm_mday);
 113         if (day != READ_RTC(0x8)) {
 114                 WRITE_RTC(0x8, day);
 115         }
 116
 117         temp = READ_RTC(0x4);
 118         if (temp & 0x40) {
 119                 /* 12 hour format */
 120                 hour = 0x40;
 121                 if (tm.tm_hour > 12) {
 122                         hour |= 0x20 | (BIN2BCD(hour-12) & 0x1f);
 123                 } else {
 124                         hour |= BIN2BCD(tm.tm_hour);
 125                 }
 126         } else {
 127                 /* 24 hour format */
 128                 hour = BIN2BCD(tm.tm_hour) & 0x3f;
 129         }
 130         if (hour != temp) WRITE_RTC(0x4, hour);
 131
 132         minute = BIN2BCD(tm.tm_min);
 133         if (minute != READ_RTC(0x2)) {
 134                 WRITE_RTC(0x2, minute);
 135         }
 136
 137         second = BIN2BCD(tm.tm_sec);
 138         if (second != READ_RTC(0x1)) {
 139                 WRITE_RTC(0x1, second);
 140         }
 141         spin_unlock_irqrestore(&rtc_lock, flags);
 142
 143         return 0;
 144 }
 145
 146 void
 147 rtc_ds1386_init(unsigned long base)
 148 {
 149         unsigned char byte;
 150
 151         /* remember the base */
 152         rtc_base = base;
 153         db_assert((rtc_base & 0xe0000000) == KSEG1);
 154
 155         /* turn on RTC if it is not on */
 156         byte = READ_RTC(0x9);
 157         if (byte & 0x80) {
 158                 byte &= 0x7f;
 159                 WRITE_RTC(0x9, byte);
 160         }
 161
 162         /* enable time transfer */
 163         byte = READ_RTC(0xB);
 164         byte |= 0x80;
 165         WRITE_RTC(0xB, byte);
 166
 167         /* set the function pointers */
 168         rtc_mips_get_time = rtc_ds1386_get_time;
 169         rtc_mips_set_time = rtc_ds1386_set_time;
 170 }