drivers/rtc/ds1307.c

   1 /*
   2  * (C) Copyright 2001, 2002, 2003
   3  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   4  * Keith Outwater, keith_outwater@mvis.com`
   5  * Steven Scholz, steven.scholz@imc-berlin.de
   6  *
   7  * See file CREDITS for list of people who contributed to this
   8  * project.
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License as
  12  * published by the Free Software Foundation; either version 2 of
  13  * the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  23  * MA 02111-1307 USA
  24  */
  25
  26 /*
  27  * Date & Time support (no alarms) for Dallas Semiconductor (now Maxim)
  28  * DS1307 and DS1338 Real Time Clock (RTC).
  29  *
  30  * based on ds1337.c
  31  */
  32
  33 #include <common.h>
  34 #include <command.h>
  35 #include <rtc.h>
  36 #include <i2c.h>
  37
  38 #if defined(CONFIG_CMD_DATE)
  39
  40 /*---------------------------------------------------------------------*/
  41 #undef DEBUG_RTC
  42
  43 #ifdef DEBUG_RTC
  44 #define DEBUGR(fmt,args...) printf(fmt ,##args)
  45 #else
  46 #define DEBUGR(fmt,args...)
  47 #endif
  48 /*---------------------------------------------------------------------*/
  49
  50 #ifndef CONFIG_SYS_I2C_RTC_ADDR
  51 # define CONFIG_SYS_I2C_RTC_ADDR        0x68
  52 #endif
  53
  54 #if defined(CONFIG_RTC_DS1307) && (CONFIG_SYS_I2C_SPEED > 100000)
  55 # error The DS1307 is specified only up to 100kHz!
  56 #endif
  57
  58 /*
  59  * RTC register addresses
  60  */
  61 #define RTC_SEC_REG_ADDR        0x00
  62 #define RTC_MIN_REG_ADDR        0x01
  63 #define RTC_HR_REG_ADDR         0x02
  64 #define RTC_DAY_REG_ADDR        0x03
  65 #define RTC_DATE_REG_ADDR       0x04
  66 #define RTC_MON_REG_ADDR        0x05
  67 #define RTC_YR_REG_ADDR         0x06
  68 #define RTC_CTL_REG_ADDR        0x07
  69
  70 #define RTC_SEC_BIT_CH          0x80    /* Clock Halt (in Register 0)   */
  71
  72 #define RTC_CTL_BIT_RS0         0x01    /* Rate select 0                */
  73 #define RTC_CTL_BIT_RS1         0x02    /* Rate select 1                */
  74 #define RTC_CTL_BIT_SQWE        0x10    /* Square Wave Enable           */
  75 #define RTC_CTL_BIT_OUT         0x80    /* Output Control               */
  76
  77 static uchar rtc_read (uchar reg);
  78 static void rtc_write (uchar reg, uchar val);
  79 static uchar bin2bcd (unsigned int n);
  80 static unsigned bcd2bin (uchar c);
  81
  82 /*
  83  * Get the current time from the RTC
  84  */
  85 int rtc_get (struct rtc_time *tmp)
  86 {
  87         int rel = 0;
  88         uchar sec, min, hour, mday, wday, mon, year;
  89
  90         sec = rtc_read (RTC_SEC_REG_ADDR);
  91         min = rtc_read (RTC_MIN_REG_ADDR);
  92         hour = rtc_read (RTC_HR_REG_ADDR);
  93         wday = rtc_read (RTC_DAY_REG_ADDR);
  94         mday = rtc_read (RTC_DATE_REG_ADDR);
  95         mon = rtc_read (RTC_MON_REG_ADDR);
  96         year = rtc_read (RTC_YR_REG_ADDR);
  97
  98         DEBUGR ("Get RTC year: %02x mon: %02x mday: %02x wday: %02x "
  99                 "hr: %02x min: %02x sec: %02x\n",
 100                 year, mon, mday, wday, hour, min, sec);
 101
 102         if (sec & RTC_SEC_BIT_CH) {
 103                 printf ("### Warning: RTC oscillator has stopped\n");
 104                 /* clear the CH flag */
 105                 rtc_write (RTC_SEC_REG_ADDR,
 106                            rtc_read (RTC_SEC_REG_ADDR) & ~RTC_SEC_BIT_CH);
 107                 rel = -1;
 108         }
 109
 110         tmp->tm_sec  = bcd2bin (sec & 0x7F);
 111         tmp->tm_min  = bcd2bin (min & 0x7F);
 112         tmp->tm_hour = bcd2bin (hour & 0x3F);
 113         tmp->tm_mday = bcd2bin (mday & 0x3F);
 114         tmp->tm_mon  = bcd2bin (mon & 0x1F);
 115         tmp->tm_year = bcd2bin (year) + ( bcd2bin (year) >= 70 ? 1900 : 2000);
 116         tmp->tm_wday = bcd2bin ((wday - 1) & 0x07);
 117         tmp->tm_yday = 0;
 118         tmp->tm_isdst= 0;
 119
 120         DEBUGR ("Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 121                 tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
 122                 tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
 123
 124         return rel;
 125 }
 126
 127
 128 /*
 129  * Set the RTC
 130  */
 131 int rtc_set (struct rtc_time *tmp)
 132 {
 133         DEBUGR ("Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 134                 tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
 135                 tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
 136
 137         if (tmp->tm_year < 1970 || tmp->tm_year > 2069)
 138                 printf("WARNING: year should be between 1970 and 2069!\n");
 139
 140         rtc_write (RTC_YR_REG_ADDR, bin2bcd (tmp->tm_year % 100));
 141         rtc_write (RTC_MON_REG_ADDR, bin2bcd (tmp->tm_mon));
 142         rtc_write (RTC_DAY_REG_ADDR, bin2bcd (tmp->tm_wday + 1));
 143         rtc_write (RTC_DATE_REG_ADDR, bin2bcd (tmp->tm_mday));
 144         rtc_write (RTC_HR_REG_ADDR, bin2bcd (tmp->tm_hour));
 145         rtc_write (RTC_MIN_REG_ADDR, bin2bcd (tmp->tm_min));
 146         rtc_write (RTC_SEC_REG_ADDR, bin2bcd (tmp->tm_sec));
 147
 148         return 0;
 149 }
 150
 151
 152 /*
 153  * Reset the RTC. We setting the date back to 1970-01-01.
 154  * We also enable the oscillator output on the SQW/OUT pin and program
 155  * it for 32,768 Hz output. Note that according to the datasheet, turning
 156  * on the square wave output increases the current drain on the backup
 157  * battery to something between 480nA and 800nA.
 158  */
 159 void rtc_reset (void)
 160 {
 161         struct rtc_time tmp;
 162
 163         rtc_write (RTC_SEC_REG_ADDR, 0x00);     /* clearing Clock Halt  */
 164         rtc_write (RTC_CTL_REG_ADDR, RTC_CTL_BIT_SQWE | RTC_CTL_BIT_RS1 | RTC_CTL_BIT_RS0);
 165
 166         tmp.tm_year = 1970;
 167         tmp.tm_mon = 1;
 168         tmp.tm_mday= 1;
 169         tmp.tm_hour = 0;
 170         tmp.tm_min = 0;
 171         tmp.tm_sec = 0;
 172
 173         rtc_set(&tmp);
 174
 175         printf ( "RTC:   %4d-%02d-%02d %2d:%02d:%02d UTC\n",
 176                 tmp.tm_year, tmp.tm_mon, tmp.tm_mday,
 177                 tmp.tm_hour, tmp.tm_min, tmp.tm_sec);
 178
 179         return;
 180 }
 181
 182
 183 /*
 184  * Helper functions
 185  */
 186
 187 static
 188 uchar rtc_read (uchar reg)
 189 {
 190         return (i2c_reg_read (CONFIG_SYS_I2C_RTC_ADDR, reg));
 191 }
 192
 193
 194 static void rtc_write (uchar reg, uchar val)
 195 {
 196         i2c_reg_write (CONFIG_SYS_I2C_RTC_ADDR, reg, val);
 197 }
 198
 199 static unsigned bcd2bin (uchar n)
 200 {
 201         return ((((n >> 4) & 0x0F) * 10) + (n & 0x0F));
 202 }
 203
 204 static unsigned char bin2bcd (unsigned int n)
 205 {
 206         return (((n / 10) << 4) | (n % 10));
 207 }
 208
 209 #endif