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 172