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  * SPDX-License-Identifier:     GPL-2.0+
   8  */
   9
  10 /*
  11  * Date & Time support (no alarms) for Dallas Semiconductor (now Maxim)
  12  * DS1307 and DS1338 Real Time Clock (RTC).
  13  *
  14  * based on ds1337.c
  15  */
  16
  17 #include <common.h>
  18 #include <command.h>
  19 #include <rtc.h>
  20 #include <i2c.h>
  21
  22 #if defined(CONFIG_CMD_DATE)
  23
  24 /*---------------------------------------------------------------------*/
  25 #undef DEBUG_RTC
  26
  27 #ifdef DEBUG_RTC
  28 #define DEBUGR(fmt,args...) printf(fmt ,##args)
  29 #else
  30 #define DEBUGR(fmt,args...)
  31 #endif
  32 /*---------------------------------------------------------------------*/
  33
  34 #ifndef CONFIG_SYS_I2C_RTC_ADDR
  35 # define CONFIG_SYS_I2C_RTC_ADDR        0x68
  36 #endif
  37
  38 #if defined(CONFIG_RTC_DS1307) && (CONFIG_SYS_I2C_SPEED > 100000)
  39 # error The DS1307 is specified only up to 100kHz!
  40 #endif
  41
  42 /*
  43  * RTC register addresses
  44  */
  45 #define RTC_SEC_REG_ADDR        0x00
  46 #define RTC_MIN_REG_ADDR        0x01
  47 #define RTC_HR_REG_ADDR         0x02
  48 #define RTC_DAY_REG_ADDR        0x03
  49 #define RTC_DATE_REG_ADDR       0x04
  50 #define RTC_MON_REG_ADDR        0x05
  51 #define RTC_YR_REG_ADDR         0x06
  52 #define RTC_CTL_REG_ADDR        0x07
  53
  54 #define RTC_SEC_BIT_CH          0x80    /* Clock Halt (in Register 0)   */
  55
  56 #define RTC_CTL_BIT_RS0         0x01    /* Rate select 0                */
  57 #define RTC_CTL_BIT_RS1         0x02    /* Rate select 1                */
  58 #define RTC_CTL_BIT_SQWE        0x10    /* Square Wave Enable           */
  59 #define RTC_CTL_BIT_OUT         0x80    /* Output Control               */
  60
  61 static uchar rtc_read (uchar reg);
  62 static void rtc_write (uchar reg, uchar val);
  63
  64 /*
  65  * Get the current time from the RTC
  66  */
  67 int rtc_get (struct rtc_time *tmp)
  68 {
  69         int rel = 0;
  70         uchar sec, min, hour, mday, wday, mon, year;
  71
  72         sec = rtc_read (RTC_SEC_REG_ADDR);
  73         min = rtc_read (RTC_MIN_REG_ADDR);
  74         hour = rtc_read (RTC_HR_REG_ADDR);
  75         wday = rtc_read (RTC_DAY_REG_ADDR);
  76         mday = rtc_read (RTC_DATE_REG_ADDR);
  77         mon = rtc_read (RTC_MON_REG_ADDR);
  78         year = rtc_read (RTC_YR_REG_ADDR);
  79
  80         DEBUGR ("Get RTC year: %02x mon: %02x mday: %02x wday: %02x "
  81                 "hr: %02x min: %02x sec: %02x\n",
  82                 year, mon, mday, wday, hour, min, sec);
  83
  84         if (sec & RTC_SEC_BIT_CH) {
  85                 printf ("### Warning: RTC oscillator has stopped\n");
  86                 /* clear the CH flag */
  87                 rtc_write (RTC_SEC_REG_ADDR,
  88                            rtc_read (RTC_SEC_REG_ADDR) & ~RTC_SEC_BIT_CH);
  89                 rel = -1;
  90         }
  91
  92         tmp->tm_sec  = bcd2bin (sec & 0x7F);
  93         tmp->tm_min  = bcd2bin (min & 0x7F);
  94         tmp->tm_hour = bcd2bin (hour & 0x3F);
  95         tmp->tm_mday = bcd2bin (mday & 0x3F);
  96         tmp->tm_mon  = bcd2bin (mon & 0x1F);
  97         tmp->tm_year = bcd2bin (year) + ( bcd2bin (year) >= 70 ? 1900 : 2000);
  98         tmp->tm_wday = bcd2bin ((wday - 1) & 0x07);
  99         tmp->tm_yday = 0;
 100         tmp->tm_isdst= 0;
 101
 102         DEBUGR ("Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 103                 tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
 104                 tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
 105
 106         return rel;
 107 }
 108
 109
 110 /*
 111  * Set the RTC
 112  */
 113 int rtc_set (struct rtc_time *tmp)
 114 {
 115         DEBUGR ("Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 116                 tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
 117                 tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
 118
 119         if (tmp->tm_year < 1970 || tmp->tm_year > 2069)
 120                 printf("WARNING: year should be between 1970 and 2069!\n");
 121
 122         rtc_write (RTC_YR_REG_ADDR, bin2bcd (tmp->tm_year % 100));
 123         rtc_write (RTC_MON_REG_ADDR, bin2bcd (tmp->tm_mon));
 124         rtc_write (RTC_DAY_REG_ADDR, bin2bcd (tmp->tm_wday + 1));
 125         rtc_write (RTC_DATE_REG_ADDR, bin2bcd (tmp->tm_mday));
 126         rtc_write (RTC_HR_REG_ADDR, bin2bcd (tmp->tm_hour));
 127         rtc_write (RTC_MIN_REG_ADDR, bin2bcd (tmp->tm_min));
 128         rtc_write (RTC_SEC_REG_ADDR, bin2bcd (tmp->tm_sec));
 129
 130         return 0;
 131 }
 132
 133
 134 /*
 135  * Reset the RTC. We setting the date back to 1970-01-01.
 136  * We also enable the oscillator output on the SQW/OUT pin and program
 137  * it for 32,768 Hz output. Note that according to the datasheet, turning
 138  * on the square wave output increases the current drain on the backup
 139  * battery to something between 480nA and 800nA.
 140  */
 141 void rtc_reset (void)
 142 {
 143         struct rtc_time tmp;
 144
 145         rtc_write (RTC_SEC_REG_ADDR, 0x00);     /* clearing Clock Halt  */
 146         rtc_write (RTC_CTL_REG_ADDR, RTC_CTL_BIT_SQWE | RTC_CTL_BIT_RS1 | RTC_CTL_BIT_RS0);
 147
 148         tmp.tm_year = 1970;
 149         tmp.tm_mon = 1;
 150         tmp.tm_mday= 1;
 151         tmp.tm_hour = 0;
 152         tmp.tm_min = 0;
 153         tmp.tm_sec = 0;
 154
 155         rtc_set(&tmp);
 156
 157         printf ( "RTC:   %4d-%02d-%02d %2d:%02d:%02d UTC\n",
 158                 tmp.tm_year, tmp.tm_mon, tmp.tm_mday,
 159                 tmp.tm_hour, tmp.tm_min, tmp.tm_sec);
 160
 161         return;
 162 }
 163
 164
 165 /*
 166  * Helper functions
 167  */
 168
 169 static
 170 uchar rtc_read (uchar reg)
 171 {
 172         return (i2c_reg_read (CONFIG_SYS_I2C_RTC_ADDR, reg));
 173 }
 174
 175
 176 static void rtc_write (uchar reg, uchar val)
 177 {
 178         i2c_reg_write (CONFIG_SYS_I2C_RTC_ADDR, reg, val);
 179 }
 180 #endif