drivers/rtc/ds3231.c

   1 /*
   2  * (C) Copyright 2006
   3  * Markus Klotzbuecher, mk@denx.de
   4  *
   5  * SPDX-License-Identifier:     GPL-2.0+
   6  */
   7
   8 /*
   9  * Date & Time support (no alarms) for Dallas Semiconductor (now Maxim)
  10  * Extremly Accurate DS3231 Real Time Clock (RTC).
  11  *
  12  * copied from ds1337.c
  13  */
  14
  15 #include <common.h>
  16 #include <command.h>
  17 #include <rtc.h>
  18 #include <i2c.h>
  19
  20 #if defined(CONFIG_CMD_DATE)
  21
  22 /*
  23  * RTC register addresses
  24  */
  25 #define RTC_SEC_REG_ADDR        0x0
  26 #define RTC_MIN_REG_ADDR        0x1
  27 #define RTC_HR_REG_ADDR         0x2
  28 #define RTC_DAY_REG_ADDR        0x3
  29 #define RTC_DATE_REG_ADDR       0x4
  30 #define RTC_MON_REG_ADDR        0x5
  31 #define RTC_YR_REG_ADDR         0x6
  32 #define RTC_CTL_REG_ADDR        0x0e
  33 #define RTC_STAT_REG_ADDR       0x0f
  34
  35
  36 /*
  37  * RTC control register bits
  38  */
  39 #define RTC_CTL_BIT_A1IE        0x1     /* Alarm 1 interrupt enable     */
  40 #define RTC_CTL_BIT_A2IE        0x2     /* Alarm 2 interrupt enable     */
  41 #define RTC_CTL_BIT_INTCN       0x4     /* Interrupt control            */
  42 #define RTC_CTL_BIT_RS1         0x8     /* Rate select 1                */
  43 #define RTC_CTL_BIT_RS2         0x10    /* Rate select 2                */
  44 #define RTC_CTL_BIT_DOSC        0x80    /* Disable Oscillator           */
  45
  46 /*
  47  * RTC status register bits
  48  */
  49 #define RTC_STAT_BIT_A1F        0x1     /* Alarm 1 flag                 */
  50 #define RTC_STAT_BIT_A2F        0x2     /* Alarm 2 flag                 */
  51 #define RTC_STAT_BIT_OSF        0x80    /* Oscillator stop flag         */
  52 #define RTC_STAT_BIT_BB32KHZ    0x40    /* Battery backed 32KHz Output  */
  53 #define RTC_STAT_BIT_EN32KHZ    0x8     /* Enable 32KHz Output  */
  54
  55
  56 static uchar rtc_read (uchar reg);
  57 static void rtc_write (uchar reg, uchar val);
  58
  59
  60 /*
  61  * Get the current time from the RTC
  62  */
  63 int rtc_get (struct rtc_time *tmp)
  64 {
  65         int rel = 0;
  66         uchar sec, min, hour, mday, wday, mon_cent, year, control, status;
  67
  68         control = rtc_read (RTC_CTL_REG_ADDR);
  69         status = rtc_read (RTC_STAT_REG_ADDR);
  70         sec = rtc_read (RTC_SEC_REG_ADDR);
  71         min = rtc_read (RTC_MIN_REG_ADDR);
  72         hour = rtc_read (RTC_HR_REG_ADDR);
  73         wday = rtc_read (RTC_DAY_REG_ADDR);
  74         mday = rtc_read (RTC_DATE_REG_ADDR);
  75         mon_cent = rtc_read (RTC_MON_REG_ADDR);
  76         year = rtc_read (RTC_YR_REG_ADDR);
  77
  78         debug("Get RTC year: %02x mon/cent: %02x mday: %02x wday: %02x "
  79                 "hr: %02x min: %02x sec: %02x control: %02x status: %02x\n",
  80                 year, mon_cent, mday, wday, hour, min, sec, control, status);
  81
  82         if (status & RTC_STAT_BIT_OSF) {
  83                 printf ("### Warning: RTC oscillator has stopped\n");
  84                 /* clear the OSF flag */
  85                 rtc_write (RTC_STAT_REG_ADDR,
  86                            rtc_read (RTC_STAT_REG_ADDR) & ~RTC_STAT_BIT_OSF);
  87                 rel = -1;
  88         }
  89
  90         tmp->tm_sec  = bcd2bin (sec & 0x7F);
  91         tmp->tm_min  = bcd2bin (min & 0x7F);
  92         tmp->tm_hour = bcd2bin (hour & 0x3F);
  93         tmp->tm_mday = bcd2bin (mday & 0x3F);
  94         tmp->tm_mon  = bcd2bin (mon_cent & 0x1F);
  95         tmp->tm_year = bcd2bin (year) + ((mon_cent & 0x80) ? 2000 : 1900);
  96         tmp->tm_wday = bcd2bin ((wday - 1) & 0x07);
  97         tmp->tm_yday = 0;
  98         tmp->tm_isdst= 0;
  99
 100         debug("Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 101                 tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
 102                 tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
 103
 104         return rel;
 105 }
 106
 107
 108 /*
 109  * Set the RTC
 110  */
 111 int rtc_set (struct rtc_time *tmp)
 112 {
 113         uchar century;
 114
 115         debug("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         rtc_write (RTC_YR_REG_ADDR, bin2bcd (tmp->tm_year % 100));
 120
 121         century = (tmp->tm_year >= 2000) ? 0x80 : 0;
 122         rtc_write (RTC_MON_REG_ADDR, bin2bcd (tmp->tm_mon) | century);
 123
 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 also enable the oscillator output on the
 136  * SQW/INTB* pin and program it for 32,768 Hz output. Note that
 137  * according to the datasheet, turning on the square wave output
 138  * increases the current drain on the backup battery from about
 139  * 600 nA to 2uA.
 140  */
 141 void rtc_reset (void)
 142 {
 143         rtc_write (RTC_CTL_REG_ADDR, RTC_CTL_BIT_RS1 | RTC_CTL_BIT_RS2);
 144 }
 145
 146 /*
 147  * Enable 32KHz output
 148  */
 149 void rtc_enable_32khz_output(void)
 150 {
 151         rtc_write(RTC_STAT_REG_ADDR,
 152                   RTC_STAT_BIT_BB32KHZ | RTC_STAT_BIT_EN32KHZ);
 153 }
 154
 155 /*
 156  * Helper functions
 157  */
 158
 159 static
 160 uchar rtc_read (uchar reg)
 161 {
 162         return (i2c_reg_read (CONFIG_SYS_I2C_RTC_ADDR, reg));
 163 }
 164
 165
 166 static void rtc_write (uchar reg, uchar val)
 167 {
 168         i2c_reg_write (CONFIG_SYS_I2C_RTC_ADDR, reg, val);
 169 }
 170
 171 #endif