xref: /openbmc/u-boot/drivers/rtc/ds3231.c (revision 607232e4)
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 
53 
54 static uchar rtc_read (uchar reg);
55 static void rtc_write (uchar reg, uchar val);
56 
57 
58 /*
59  * Get the current time from the RTC
60  */
61 int rtc_get (struct rtc_time *tmp)
62 {
63 	int rel = 0;
64 	uchar sec, min, hour, mday, wday, mon_cent, year, control, status;
65 
66 	control = rtc_read (RTC_CTL_REG_ADDR);
67 	status = rtc_read (RTC_STAT_REG_ADDR);
68 	sec = rtc_read (RTC_SEC_REG_ADDR);
69 	min = rtc_read (RTC_MIN_REG_ADDR);
70 	hour = rtc_read (RTC_HR_REG_ADDR);
71 	wday = rtc_read (RTC_DAY_REG_ADDR);
72 	mday = rtc_read (RTC_DATE_REG_ADDR);
73 	mon_cent = rtc_read (RTC_MON_REG_ADDR);
74 	year = rtc_read (RTC_YR_REG_ADDR);
75 
76 	debug("Get RTC year: %02x mon/cent: %02x mday: %02x wday: %02x "
77 		"hr: %02x min: %02x sec: %02x control: %02x status: %02x\n",
78 		year, mon_cent, mday, wday, hour, min, sec, control, status);
79 
80 	if (status & RTC_STAT_BIT_OSF) {
81 		printf ("### Warning: RTC oscillator has stopped\n");
82 		/* clear the OSF flag */
83 		rtc_write (RTC_STAT_REG_ADDR,
84 			   rtc_read (RTC_STAT_REG_ADDR) & ~RTC_STAT_BIT_OSF);
85 		rel = -1;
86 	}
87 
88 	tmp->tm_sec  = bcd2bin (sec & 0x7F);
89 	tmp->tm_min  = bcd2bin (min & 0x7F);
90 	tmp->tm_hour = bcd2bin (hour & 0x3F);
91 	tmp->tm_mday = bcd2bin (mday & 0x3F);
92 	tmp->tm_mon  = bcd2bin (mon_cent & 0x1F);
93 	tmp->tm_year = bcd2bin (year) + ((mon_cent & 0x80) ? 2000 : 1900);
94 	tmp->tm_wday = bcd2bin ((wday - 1) & 0x07);
95 	tmp->tm_yday = 0;
96 	tmp->tm_isdst= 0;
97 
98 	debug("Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
99 		tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
100 		tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
101 
102 	return rel;
103 }
104 
105 
106 /*
107  * Set the RTC
108  */
109 int rtc_set (struct rtc_time *tmp)
110 {
111 	uchar century;
112 
113 	debug("Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
114 		tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
115 		tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
116 
117 	rtc_write (RTC_YR_REG_ADDR, bin2bcd (tmp->tm_year % 100));
118 
119 	century = (tmp->tm_year >= 2000) ? 0x80 : 0;
120 	rtc_write (RTC_MON_REG_ADDR, bin2bcd (tmp->tm_mon) | century);
121 
122 	rtc_write (RTC_DAY_REG_ADDR, bin2bcd (tmp->tm_wday + 1));
123 	rtc_write (RTC_DATE_REG_ADDR, bin2bcd (tmp->tm_mday));
124 	rtc_write (RTC_HR_REG_ADDR, bin2bcd (tmp->tm_hour));
125 	rtc_write (RTC_MIN_REG_ADDR, bin2bcd (tmp->tm_min));
126 	rtc_write (RTC_SEC_REG_ADDR, bin2bcd (tmp->tm_sec));
127 
128 	return 0;
129 }
130 
131 
132 /*
133  * Reset the RTC.  We also enable the oscillator output on the
134  * SQW/INTB* pin and program it for 32,768 Hz output. Note that
135  * according to the datasheet, turning on the square wave output
136  * increases the current drain on the backup battery from about
137  * 600 nA to 2uA.
138  */
139 void rtc_reset (void)
140 {
141 	rtc_write (RTC_CTL_REG_ADDR, RTC_CTL_BIT_RS1 | RTC_CTL_BIT_RS2);
142 }
143 
144 
145 /*
146  * Helper functions
147  */
148 
149 static
150 uchar rtc_read (uchar reg)
151 {
152 	return (i2c_reg_read (CONFIG_SYS_I2C_RTC_ADDR, reg));
153 }
154 
155 
156 static void rtc_write (uchar reg, uchar val)
157 {
158 	i2c_reg_write (CONFIG_SYS_I2C_RTC_ADDR, reg, val);
159 }
160 
161 #endif
162