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
  45         /* let us freeze external registers */
  46         byte = READ_RTC(0xB);
  47         byte &= 0x3f;
  48         WRITE_RTC(0xB, byte);
  49
  50         /* read time data */
  51         year = BCD2BIN(READ_RTC(0xA)) + EPOCH;
  52         month = BCD2BIN(READ_RTC(0x9) & 0x1f);
  53         day = BCD2BIN(READ_RTC(0x8));
  54         minute = BCD2BIN(READ_RTC(0x2));
  55         second = BCD2BIN(READ_RTC(0x1));
  56
  57         /* hour is special - deal with it later */
  58         temp = READ_RTC(0x4);
  59
  60         /* enable time transfer */
  61         byte |= 0x80;
  62         WRITE_RTC(0xB, byte);
  63
  64         /* calc hour */
  65         if (temp & 0x40) {
  66                 /* 12 hour format */
  67                 hour = BCD2BIN(temp & 0x1f);
  68                 if (temp & 0x20) hour += 12;            /* PM */
  69         } else {
  70                 /* 24 hour format */
  71                 hour = BCD2BIN(temp & 0x3f);
  72         }
  73
  74         return mktime(year, month, day, hour, minute, second);
  75 }
  76
  77 static int
  78 rtc_ds1386_set_time(unsigned long t)
  79 {
  80         struct rtc_time tm;
  81         u8 byte;
  82         u8 temp;
  83         u8 year, month, day, hour, minute, second;
  84
  85         /* let us freeze external registers */
  86         byte = READ_RTC(0xB);
  87         byte &= 0x3f;
  88         WRITE_RTC(0xB, byte);
  89
  90         /* convert */
  91         to_tm(t, &tm);
  92
  93
  94         /* check each field one by one */
  95         year = BIN2BCD(tm.tm_year - EPOCH);
  96         if (year != READ_RTC(0xA)) {
  97                 WRITE_RTC(0xA, year);
  98         }
  99
 100         temp = READ_RTC(0x9);
 101         month = BIN2BCD(tm.tm_mon+1);   /* tm_mon starts from 0 to 11 */
 102         if (month != (temp & 0x1f)) {
 103                 WRITE_RTC( 0x9,
 104                            (month & 0x1f) | (temp & ~0x1f) );
 105         }
 106
 107         day = BIN2BCD(tm.tm_mday);
 108         if (day != READ_RTC(0x8)) {
 109                 WRITE_RTC(0x8, day);
 110         }
 111
 112         temp = READ_RTC(0x4);
 113         if (temp & 0x40) {
 114                 /* 12 hour format */
 115                 hour = 0x40;
 116                 if (tm.tm_hour > 12) {
 117                         hour |= 0x20 | (BIN2BCD(hour-12) & 0x1f);
 118                 } else {
 119                         hour |= BIN2BCD(tm.tm_hour);
 120                 }
 121         } else {
 122                 /* 24 hour format */
 123                 hour = BIN2BCD(tm.tm_hour) & 0x3f;
 124         }
 125         if (hour != temp) WRITE_RTC(0x4, hour);
 126
 127         minute = BIN2BCD(tm.tm_min);
 128         if (minute != READ_RTC(0x2)) {
 129                 WRITE_RTC(0x2, minute);
 130         }
 131
 132         second = BIN2BCD(tm.tm_sec);
 133         if (second != READ_RTC(0x1)) {
 134                 WRITE_RTC(0x1, second);
 135         }
 136
 137         return 0;
 138 }
 139
 140 void
 141 rtc_ds1386_init(unsigned long base)
 142 {
 143         unsigned char byte;
 144
 145         /* remember the base */
 146         rtc_base = base;
 147         db_assert((rtc_base & 0xe0000000) == KSEG1);
 148
 149         /* turn on RTC if it is not on */
 150         byte = READ_RTC(0x9);
 151         if (byte & 0x80) {
 152                 byte &= 0x7f;
 153                 WRITE_RTC(0x9, byte);
 154         }
 155
 156         /* enable time transfer */
 157         byte = READ_RTC(0xB);
 158         byte |= 0x80;
 159         WRITE_RTC(0xB, byte);
 160
 161         /* set the function pointers */
 162         rtc_get_time = rtc_ds1386_get_time;
 163         rtc_set_time = rtc_ds1386_set_time;
 164 }