1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * (C) Copyright 2006 4 * Markus Klotzbuecher, mk@denx.de 5 */ 6 7 /* 8 * Date & Time support (no alarms) for Dallas Semiconductor (now Maxim) 9 * Extremly Accurate DS3231 Real Time Clock (RTC). 10 * 11 * copied from ds1337.c 12 */ 13 14 #include <common.h> 15 #include <command.h> 16 #include <rtc.h> 17 #include <i2c.h> 18 19 /* 20 * RTC register addresses 21 */ 22 #define RTC_SEC_REG_ADDR 0x0 23 #define RTC_MIN_REG_ADDR 0x1 24 #define RTC_HR_REG_ADDR 0x2 25 #define RTC_DAY_REG_ADDR 0x3 26 #define RTC_DATE_REG_ADDR 0x4 27 #define RTC_MON_REG_ADDR 0x5 28 #define RTC_YR_REG_ADDR 0x6 29 #define RTC_CTL_REG_ADDR 0x0e 30 #define RTC_STAT_REG_ADDR 0x0f 31 32 33 /* 34 * RTC control register bits 35 */ 36 #define RTC_CTL_BIT_A1IE 0x1 /* Alarm 1 interrupt enable */ 37 #define RTC_CTL_BIT_A2IE 0x2 /* Alarm 2 interrupt enable */ 38 #define RTC_CTL_BIT_INTCN 0x4 /* Interrupt control */ 39 #define RTC_CTL_BIT_RS1 0x8 /* Rate select 1 */ 40 #define RTC_CTL_BIT_RS2 0x10 /* Rate select 2 */ 41 #define RTC_CTL_BIT_DOSC 0x80 /* Disable Oscillator */ 42 43 /* 44 * RTC status register bits 45 */ 46 #define RTC_STAT_BIT_A1F 0x1 /* Alarm 1 flag */ 47 #define RTC_STAT_BIT_A2F 0x2 /* Alarm 2 flag */ 48 #define RTC_STAT_BIT_OSF 0x80 /* Oscillator stop flag */ 49 #define RTC_STAT_BIT_BB32KHZ 0x40 /* Battery backed 32KHz Output */ 50 #define RTC_STAT_BIT_EN32KHZ 0x8 /* Enable 32KHz Output */ 51 52 53 static uchar rtc_read (uchar reg); 54 static void rtc_write (uchar reg, uchar val); 55 56 57 /* 58 * Get the current time from the RTC 59 */ 60 int rtc_get (struct rtc_time *tmp) 61 { 62 int rel = 0; 63 uchar sec, min, hour, mday, wday, mon_cent, year, control, status; 64 65 control = rtc_read (RTC_CTL_REG_ADDR); 66 status = rtc_read (RTC_STAT_REG_ADDR); 67 sec = rtc_read (RTC_SEC_REG_ADDR); 68 min = rtc_read (RTC_MIN_REG_ADDR); 69 hour = rtc_read (RTC_HR_REG_ADDR); 70 wday = rtc_read (RTC_DAY_REG_ADDR); 71 mday = rtc_read (RTC_DATE_REG_ADDR); 72 mon_cent = rtc_read (RTC_MON_REG_ADDR); 73 year = rtc_read (RTC_YR_REG_ADDR); 74 75 debug("Get RTC year: %02x mon/cent: %02x mday: %02x wday: %02x " 76 "hr: %02x min: %02x sec: %02x control: %02x status: %02x\n", 77 year, mon_cent, mday, wday, hour, min, sec, control, status); 78 79 if (status & RTC_STAT_BIT_OSF) { 80 printf ("### Warning: RTC oscillator has stopped\n"); 81 /* clear the OSF flag */ 82 rtc_write (RTC_STAT_REG_ADDR, 83 rtc_read (RTC_STAT_REG_ADDR) & ~RTC_STAT_BIT_OSF); 84 rel = -1; 85 } 86 87 tmp->tm_sec = bcd2bin (sec & 0x7F); 88 tmp->tm_min = bcd2bin (min & 0x7F); 89 tmp->tm_hour = bcd2bin (hour & 0x3F); 90 tmp->tm_mday = bcd2bin (mday & 0x3F); 91 tmp->tm_mon = bcd2bin (mon_cent & 0x1F); 92 tmp->tm_year = bcd2bin (year) + ((mon_cent & 0x80) ? 2000 : 1900); 93 tmp->tm_wday = bcd2bin ((wday - 1) & 0x07); 94 tmp->tm_yday = 0; 95 tmp->tm_isdst= 0; 96 97 debug("Get DATE: %4d-%02d-%02d (wday=%d) TIME: %2d:%02d:%02d\n", 98 tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday, 99 tmp->tm_hour, tmp->tm_min, tmp->tm_sec); 100 101 return rel; 102 } 103 104 105 /* 106 * Set the RTC 107 */ 108 int rtc_set (struct rtc_time *tmp) 109 { 110 uchar century; 111 112 debug("Set DATE: %4d-%02d-%02d (wday=%d) TIME: %2d:%02d:%02d\n", 113 tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday, 114 tmp->tm_hour, tmp->tm_min, tmp->tm_sec); 115 116 rtc_write (RTC_YR_REG_ADDR, bin2bcd (tmp->tm_year % 100)); 117 118 century = (tmp->tm_year >= 2000) ? 0x80 : 0; 119 rtc_write (RTC_MON_REG_ADDR, bin2bcd (tmp->tm_mon) | century); 120 121 rtc_write (RTC_DAY_REG_ADDR, bin2bcd (tmp->tm_wday + 1)); 122 rtc_write (RTC_DATE_REG_ADDR, bin2bcd (tmp->tm_mday)); 123 rtc_write (RTC_HR_REG_ADDR, bin2bcd (tmp->tm_hour)); 124 rtc_write (RTC_MIN_REG_ADDR, bin2bcd (tmp->tm_min)); 125 rtc_write (RTC_SEC_REG_ADDR, bin2bcd (tmp->tm_sec)); 126 127 return 0; 128 } 129 130 131 /* 132 * Reset the RTC. We also enable the oscillator output on the 133 * SQW/INTB* pin and program it for 32,768 Hz output. Note that 134 * according to the datasheet, turning on the square wave output 135 * increases the current drain on the backup battery from about 136 * 600 nA to 2uA. 137 */ 138 void rtc_reset (void) 139 { 140 rtc_write (RTC_CTL_REG_ADDR, RTC_CTL_BIT_RS1 | RTC_CTL_BIT_RS2); 141 } 142 143 /* 144 * Enable 32KHz output 145 */ 146 void rtc_enable_32khz_output(void) 147 { 148 rtc_write(RTC_STAT_REG_ADDR, 149 RTC_STAT_BIT_BB32KHZ | RTC_STAT_BIT_EN32KHZ); 150 } 151 152 /* 153 * Helper functions 154 */ 155 156 static 157 uchar rtc_read (uchar reg) 158 { 159 return (i2c_reg_read (CONFIG_SYS_I2C_RTC_ADDR, reg)); 160 } 161 162 163 static void rtc_write (uchar reg, uchar val) 164 { 165 i2c_reg_write (CONFIG_SYS_I2C_RTC_ADDR, reg, val); 166 } 167