drivers/rtc/ds1337.c

   1 /*
   2  * (C) Copyright 2001, 2002
   3  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   4  * Keith Outwater, keith_outwater@mvis.com`
   5  *
   6  * See file CREDITS for list of people who contributed to this
   7  * project.
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License as
  11  * published by the Free Software Foundation; either version 2 of
  12  * the License, or (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  22  * MA 02111-1307 USA
  23  */
  24
  25 /*
  26  * Date & Time support (no alarms) for Dallas Semiconductor (now Maxim)
  27  * DS1337 Real Time Clock (RTC).
  28  */
  29
  30 #include <common.h>
  31 #include <command.h>
  32 #include <rtc.h>
  33 #include <i2c.h>
  34
  35 #if defined(CONFIG_RTC_DS1337) && defined(CONFIG_CMD_DATE)
  36
  37 /*---------------------------------------------------------------------*/
  38 #undef DEBUG_RTC
  39
  40 #ifdef DEBUG_RTC
  41 #define DEBUGR(fmt,args...) printf(fmt ,##args)
  42 #else
  43 #define DEBUGR(fmt,args...)
  44 #endif
  45 /*---------------------------------------------------------------------*/
  46
  47 /*
  48  * RTC register addresses
  49  */
  50 #define RTC_SEC_REG_ADDR        0x0
  51 #define RTC_MIN_REG_ADDR        0x1
  52 #define RTC_HR_REG_ADDR         0x2
  53 #define RTC_DAY_REG_ADDR        0x3
  54 #define RTC_DATE_REG_ADDR       0x4
  55 #define RTC_MON_REG_ADDR        0x5
  56 #define RTC_YR_REG_ADDR         0x6
  57 #define RTC_CTL_REG_ADDR        0x0e
  58 #define RTC_STAT_REG_ADDR       0x0f
  59
  60 /*
  61  * RTC control register bits
  62  */
  63 #define RTC_CTL_BIT_A1IE        0x1     /* Alarm 1 interrupt enable     */
  64 #define RTC_CTL_BIT_A2IE        0x2     /* Alarm 2 interrupt enable     */
  65 #define RTC_CTL_BIT_INTCN       0x4     /* Interrupt control            */
  66 #define RTC_CTL_BIT_RS1         0x8     /* Rate select 1                */
  67 #define RTC_CTL_BIT_RS2         0x10    /* Rate select 2                */
  68 #define RTC_CTL_BIT_DOSC        0x80    /* Disable Oscillator           */
  69
  70 /*
  71  * RTC status register bits
  72  */
  73 #define RTC_STAT_BIT_A1F        0x1     /* Alarm 1 flag                 */
  74 #define RTC_STAT_BIT_A2F        0x2     /* Alarm 2 flag                 */
  75 #define RTC_STAT_BIT_OSF        0x80    /* Oscillator stop flag         */
  76
  77
  78 static uchar rtc_read (uchar reg);
  79 static void rtc_write (uchar reg, uchar val);
  80 static uchar bin2bcd (unsigned int n);
  81 static unsigned bcd2bin (uchar c);
  82
  83
  84 /*
  85  * Get the current time from the RTC
  86  */
  87 int rtc_get (struct rtc_time *tmp)
  88 {
  89         int rel = 0;
  90         uchar sec, min, hour, mday, wday, mon_cent, year, control, status;
  91
  92         control = rtc_read (RTC_CTL_REG_ADDR);
  93         status = rtc_read (RTC_STAT_REG_ADDR);
  94         sec = rtc_read (RTC_SEC_REG_ADDR);
  95         min = rtc_read (RTC_MIN_REG_ADDR);
  96         hour = rtc_read (RTC_HR_REG_ADDR);
  97         wday = rtc_read (RTC_DAY_REG_ADDR);
  98         mday = rtc_read (RTC_DATE_REG_ADDR);
  99         mon_cent = rtc_read (RTC_MON_REG_ADDR);
 100         year = rtc_read (RTC_YR_REG_ADDR);
 101
 102         DEBUGR ("Get RTC year: %02x mon/cent: %02x mday: %02x wday: %02x "
 103                 "hr: %02x min: %02x sec: %02x control: %02x status: %02x\n",
 104                 year, mon_cent, mday, wday, hour, min, sec, control, status);
 105
 106         if (status & RTC_STAT_BIT_OSF) {
 107                 printf ("### Warning: RTC oscillator has stopped\n");
 108                 /* clear the OSF flag */
 109                 rtc_write (RTC_STAT_REG_ADDR,
 110                            rtc_read (RTC_STAT_REG_ADDR) & ~RTC_STAT_BIT_OSF);
 111                 rel = -1;
 112         }
 113
 114         tmp->tm_sec  = bcd2bin (sec & 0x7F);
 115         tmp->tm_min  = bcd2bin (min & 0x7F);
 116         tmp->tm_hour = bcd2bin (hour & 0x3F);
 117         tmp->tm_mday = bcd2bin (mday & 0x3F);
 118         tmp->tm_mon  = bcd2bin (mon_cent & 0x1F);
 119         tmp->tm_year = bcd2bin (year) + ((mon_cent & 0x80) ? 2000 : 1900);
 120         tmp->tm_wday = bcd2bin ((wday - 1) & 0x07);
 121         tmp->tm_yday = 0;
 122         tmp->tm_isdst= 0;
 123
 124         DEBUGR ("Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 125                 tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
 126                 tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
 127
 128         return rel;
 129 }
 130
 131
 132 /*
 133  * Set the RTC
 134  */
 135 void rtc_set (struct rtc_time *tmp)
 136 {
 137         uchar century;
 138
 139         DEBUGR ("Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 140                 tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
 141                 tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
 142
 143         rtc_write (RTC_YR_REG_ADDR, bin2bcd (tmp->tm_year % 100));
 144
 145         century = (tmp->tm_year >= 2000) ? 0x80 : 0;
 146         rtc_write (RTC_MON_REG_ADDR, bin2bcd (tmp->tm_mon) | century);
 147
 148         rtc_write (RTC_DAY_REG_ADDR, bin2bcd (tmp->tm_wday + 1));
 149         rtc_write (RTC_DATE_REG_ADDR, bin2bcd (tmp->tm_mday));
 150         rtc_write (RTC_HR_REG_ADDR, bin2bcd (tmp->tm_hour));
 151         rtc_write (RTC_MIN_REG_ADDR, bin2bcd (tmp->tm_min));
 152         rtc_write (RTC_SEC_REG_ADDR, bin2bcd (tmp->tm_sec));
 153 }
 154
 155
 156 /*
 157  * Reset the RTC.  We also enable the oscillator output on the
 158  * SQW/INTB* pin and program it for 32,768 Hz output. Note that
 159  * according to the datasheet, turning on the square wave output
 160  * increases the current drain on the backup battery from about
 161  * 600 nA to 2uA.
 162  */
 163 void rtc_reset (void)
 164 {
 165         rtc_write (RTC_CTL_REG_ADDR, RTC_CTL_BIT_RS1 | RTC_CTL_BIT_RS2);
 166 }
 167
 168
 169 /*
 170  * Helper functions
 171  */
 172
 173 static
 174 uchar rtc_read (uchar reg)
 175 {
 176         return (i2c_reg_read (CFG_I2C_RTC_ADDR, reg));
 177 }
 178
 179
 180 static void rtc_write (uchar reg, uchar val)
 181 {
 182         i2c_reg_write (CFG_I2C_RTC_ADDR, reg, val);
 183 }
 184
 185 static unsigned bcd2bin (uchar n)
 186 {
 187         return ((((n >> 4) & 0x0F) * 10) + (n & 0x0F));
 188 }
 189
 190 static unsigned char bin2bcd (unsigned int n)
 191 {
 192         return (((n / 10) << 4) | (n % 10));
 193 }
 194
 195 #endif