xref: /openbmc/u-boot/drivers/rtc/ds3231.c (revision 25793f76)
1  /*
2   * (C) Copyright 2006
3   * Markus Klotzbuecher, mk@denx.de
4   *
5   * See file CREDITS for list of people who contributed to this
6   * project.
7   *
8   * This program is free software; you can redistribute it and/or
9   * modify it under the terms of the GNU General Public License as
10   * published by the Free Software Foundation; either version 2 of
11   * the License, or (at your option) any later version.
12   *
13   * This program is distributed in the hope that it will be useful,
14   * but WITHOUT ANY WARRANTY; without even the implied warranty of
15   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16   * GNU General Public License for more details.
17   *
18   * You should have received a copy of the GNU General Public License
19   * along with this program; if not, write to the Free Software
20   * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
21   * MA 02111-1307 USA
22   */
23  
24  /*
25   * Date & Time support (no alarms) for Dallas Semiconductor (now Maxim)
26   * Extremly Accurate DS3231 Real Time Clock (RTC).
27   *
28   * copied from ds1337.c
29   */
30  
31  #include <common.h>
32  #include <command.h>
33  #include <rtc.h>
34  #include <i2c.h>
35  
36  #if defined(CONFIG_CMD_DATE)
37  
38  /*---------------------------------------------------------------------*/
39  #undef DEBUG_RTC
40  
41  #ifdef DEBUG_RTC
42  #define DEBUGR(fmt,args...) printf(fmt ,##args)
43  #else
44  #define DEBUGR(fmt,args...)
45  #endif
46  /*---------------------------------------------------------------------*/
47  
48  /*
49   * RTC register addresses
50   */
51  #define RTC_SEC_REG_ADDR	0x0
52  #define RTC_MIN_REG_ADDR	0x1
53  #define RTC_HR_REG_ADDR		0x2
54  #define RTC_DAY_REG_ADDR	0x3
55  #define RTC_DATE_REG_ADDR	0x4
56  #define RTC_MON_REG_ADDR	0x5
57  #define RTC_YR_REG_ADDR		0x6
58  #define RTC_CTL_REG_ADDR	0x0e
59  #define RTC_STAT_REG_ADDR	0x0f
60  
61  
62  /*
63   * RTC control register bits
64   */
65  #define RTC_CTL_BIT_A1IE	0x1	/* Alarm 1 interrupt enable     */
66  #define RTC_CTL_BIT_A2IE	0x2	/* Alarm 2 interrupt enable     */
67  #define RTC_CTL_BIT_INTCN	0x4	/* Interrupt control            */
68  #define RTC_CTL_BIT_RS1		0x8	/* Rate select 1                */
69  #define RTC_CTL_BIT_RS2		0x10	/* Rate select 2                */
70  #define RTC_CTL_BIT_DOSC	0x80	/* Disable Oscillator           */
71  
72  /*
73   * RTC status register bits
74   */
75  #define RTC_STAT_BIT_A1F	0x1	/* Alarm 1 flag                 */
76  #define RTC_STAT_BIT_A2F	0x2	/* Alarm 2 flag                 */
77  #define RTC_STAT_BIT_OSF	0x80	/* Oscillator stop flag         */
78  
79  
80  static uchar rtc_read (uchar reg);
81  static void rtc_write (uchar reg, uchar val);
82  
83  
84  /*
85   * Get the current time from the RTC
86   */
87  int rtc_get (struct rtc_time *tmp)
88  {
89  	int rel = 0;
90  	uchar sec, min, hour, mday, wday, mon_cent, year, control, status;
91  
92  	control = rtc_read (RTC_CTL_REG_ADDR);
93  	status = rtc_read (RTC_STAT_REG_ADDR);
94  	sec = rtc_read (RTC_SEC_REG_ADDR);
95  	min = rtc_read (RTC_MIN_REG_ADDR);
96  	hour = rtc_read (RTC_HR_REG_ADDR);
97  	wday = rtc_read (RTC_DAY_REG_ADDR);
98  	mday = rtc_read (RTC_DATE_REG_ADDR);
99  	mon_cent = rtc_read (RTC_MON_REG_ADDR);
100  	year = rtc_read (RTC_YR_REG_ADDR);
101  
102  	DEBUGR ("Get RTC year: %02x mon/cent: %02x mday: %02x wday: %02x "
103  		"hr: %02x min: %02x sec: %02x control: %02x status: %02x\n",
104  		year, mon_cent, mday, wday, hour, min, sec, control, status);
105  
106  	if (status & RTC_STAT_BIT_OSF) {
107  		printf ("### Warning: RTC oscillator has stopped\n");
108  		/* clear the OSF flag */
109  		rtc_write (RTC_STAT_REG_ADDR,
110  			   rtc_read (RTC_STAT_REG_ADDR) & ~RTC_STAT_BIT_OSF);
111  		rel = -1;
112  	}
113  
114  	tmp->tm_sec  = bcd2bin (sec & 0x7F);
115  	tmp->tm_min  = bcd2bin (min & 0x7F);
116  	tmp->tm_hour = bcd2bin (hour & 0x3F);
117  	tmp->tm_mday = bcd2bin (mday & 0x3F);
118  	tmp->tm_mon  = bcd2bin (mon_cent & 0x1F);
119  	tmp->tm_year = bcd2bin (year) + ((mon_cent & 0x80) ? 2000 : 1900);
120  	tmp->tm_wday = bcd2bin ((wday - 1) & 0x07);
121  	tmp->tm_yday = 0;
122  	tmp->tm_isdst= 0;
123  
124  	DEBUGR ("Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
125  		tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
126  		tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
127  
128  	return rel;
129  }
130  
131  
132  /*
133   * Set the RTC
134   */
135  int rtc_set (struct rtc_time *tmp)
136  {
137  	uchar century;
138  
139  	DEBUGR ("Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
140  		tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
141  		tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
142  
143  	rtc_write (RTC_YR_REG_ADDR, bin2bcd (tmp->tm_year % 100));
144  
145  	century = (tmp->tm_year >= 2000) ? 0x80 : 0;
146  	rtc_write (RTC_MON_REG_ADDR, bin2bcd (tmp->tm_mon) | century);
147  
148  	rtc_write (RTC_DAY_REG_ADDR, bin2bcd (tmp->tm_wday + 1));
149  	rtc_write (RTC_DATE_REG_ADDR, bin2bcd (tmp->tm_mday));
150  	rtc_write (RTC_HR_REG_ADDR, bin2bcd (tmp->tm_hour));
151  	rtc_write (RTC_MIN_REG_ADDR, bin2bcd (tmp->tm_min));
152  	rtc_write (RTC_SEC_REG_ADDR, bin2bcd (tmp->tm_sec));
153  
154  	return 0;
155  }
156  
157  
158  /*
159   * Reset the RTC.  We also enable the oscillator output on the
160   * SQW/INTB* pin and program it for 32,768 Hz output. Note that
161   * according to the datasheet, turning on the square wave output
162   * increases the current drain on the backup battery from about
163   * 600 nA to 2uA.
164   */
165  void rtc_reset (void)
166  {
167  	rtc_write (RTC_CTL_REG_ADDR, RTC_CTL_BIT_RS1 | RTC_CTL_BIT_RS2);
168  }
169  
170  
171  /*
172   * Helper functions
173   */
174  
175  static
176  uchar rtc_read (uchar reg)
177  {
178  	return (i2c_reg_read (CONFIG_SYS_I2C_RTC_ADDR, reg));
179  }
180  
181  
182  static void rtc_write (uchar reg, uchar val)
183  {
184  	i2c_reg_write (CONFIG_SYS_I2C_RTC_ADDR, reg, val);
185  }
186  
187  #endif
188