xref: /openbmc/u-boot/drivers/rtc/max6900.c (revision 87a62bce)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * (C) Copyright 2004
4  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
5  */
6 
7 /*
8  * Date & Time support for MAXIM MAX6900 RTC
9  */
10 
11 /* #define	DEBUG	*/
12 
13 #include <common.h>
14 #include <command.h>
15 #include <rtc.h>
16 #include <i2c.h>
17 
18 #if defined(CONFIG_CMD_DATE)
19 
20 #ifndef	CONFIG_SYS_I2C_RTC_ADDR
21 #define	CONFIG_SYS_I2C_RTC_ADDR	0x50
22 #endif
23 
24 /* ------------------------------------------------------------------------- */
25 
26 static uchar rtc_read (uchar reg)
27 {
28 	return (i2c_reg_read (CONFIG_SYS_I2C_RTC_ADDR, reg));
29 }
30 
31 static void rtc_write (uchar reg, uchar val)
32 {
33 	i2c_reg_write (CONFIG_SYS_I2C_RTC_ADDR, reg, val);
34 	udelay(2500);
35 }
36 
37 /* ------------------------------------------------------------------------- */
38 
39 int rtc_get (struct rtc_time *tmp)
40 {
41 	uchar sec, min, hour, mday, wday, mon, cent, year;
42 	int retry = 1;
43 
44 	do {
45 		sec	= rtc_read (0x80);
46 		min	= rtc_read (0x82);
47 		hour	= rtc_read (0x84);
48 		mday	= rtc_read (0x86);
49 		mon	= rtc_read (0x88);
50 		wday	= rtc_read (0x8a);
51 		year	= rtc_read (0x8c);
52 		cent	= rtc_read (0x92);
53 		/*
54 		 * Check for seconds rollover
55 		 */
56 		if ((sec != 59) || (rtc_read(0x80) == sec)){
57 			retry = 0;
58 		}
59 	} while (retry);
60 
61 	debug ( "Get RTC year: %02x mon: %02x cent: %02x mday: %02x wday: %02x "
62 		"hr: %02x min: %02x sec: %02x\n",
63 		year, mon, cent, mday, wday,
64 		hour, min, sec );
65 
66 	tmp->tm_sec  = bcd2bin (sec  & 0x7F);
67 	tmp->tm_min  = bcd2bin (min  & 0x7F);
68 	tmp->tm_hour = bcd2bin (hour & 0x3F);
69 	tmp->tm_mday = bcd2bin (mday & 0x3F);
70 	tmp->tm_mon  = bcd2bin (mon & 0x1F);
71 	tmp->tm_year = bcd2bin (year) + bcd2bin(cent) * 100;
72 	tmp->tm_wday = bcd2bin (wday & 0x07);
73 	tmp->tm_yday = 0;
74 	tmp->tm_isdst= 0;
75 
76 	debug ( "Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
77 		tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
78 		tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
79 
80 	return 0;
81 }
82 
83 int rtc_set (struct rtc_time *tmp)
84 {
85 
86 	debug ( "Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
87 		tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
88 		tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
89 
90 	rtc_write (0x9E, 0x00);
91 	rtc_write (0x80, 0);	/* Clear seconds to ensure no rollover */
92 	rtc_write (0x92, bin2bcd(tmp->tm_year / 100));
93 	rtc_write (0x8c, bin2bcd(tmp->tm_year % 100));
94 	rtc_write (0x8a, bin2bcd(tmp->tm_wday));
95 	rtc_write (0x88, bin2bcd(tmp->tm_mon));
96 	rtc_write (0x86, bin2bcd(tmp->tm_mday));
97 	rtc_write (0x84, bin2bcd(tmp->tm_hour));
98 	rtc_write (0x82, bin2bcd(tmp->tm_min ));
99 	rtc_write (0x80, bin2bcd(tmp->tm_sec ));
100 
101 	return 0;
102 }
103 
104 void rtc_reset (void)
105 {
106 }
107 
108 #endif
109