xref: /openbmc/u-boot/drivers/rtc/ds174x.c (revision aefb8f4c)
1 /*
2  * (C) Copyright 2001
3  * ARIO Data Networks, Inc. dchiu@ariodata.com
4  *
5  * Based on MontaVista DS1743 code and U-Boot mc146818 code
6  *
7  * SPDX-License-Identifier:	GPL-2.0+
8  */
9 
10 /*
11  * Date & Time support for the DS174x RTC
12  */
13 
14 /*#define	DEBUG*/
15 
16 #include <common.h>
17 #include <command.h>
18 #include <rtc.h>
19 
20 #if defined(CONFIG_CMD_DATE)
21 
22 static uchar rtc_read( unsigned int addr );
23 static void  rtc_write( unsigned int addr, uchar val);
24 
25 #define RTC_BASE		( CONFIG_SYS_NVRAM_SIZE + CONFIG_SYS_NVRAM_BASE_ADDR )
26 
27 #define RTC_YEAR		( RTC_BASE + 7 )
28 #define RTC_MONTH		( RTC_BASE + 6 )
29 #define RTC_DAY_OF_MONTH	( RTC_BASE + 5 )
30 #define RTC_DAY_OF_WEEK		( RTC_BASE + 4 )
31 #define RTC_HOURS		( RTC_BASE + 3 )
32 #define RTC_MINUTES		( RTC_BASE + 2 )
33 #define RTC_SECONDS		( RTC_BASE + 1 )
34 #define RTC_CENTURY		( RTC_BASE + 0 )
35 
36 #define RTC_CONTROLA		RTC_CENTURY
37 #define RTC_CONTROLB		RTC_SECONDS
38 #define RTC_CONTROLC		RTC_DAY_OF_WEEK
39 
40 #define RTC_CA_WRITE		0x80
41 #define RTC_CA_READ		0x40
42 
43 #define RTC_CB_OSC_DISABLE	0x80
44 
45 #define RTC_CC_BATTERY_FLAG	0x80
46 #define RTC_CC_FREQ_TEST	0x40
47 
48 /* ------------------------------------------------------------------------- */
49 
50 int rtc_get( struct rtc_time *tmp )
51 {
52 	uchar sec, min, hour;
53 	uchar mday, wday, mon, year;
54 
55 	int century;
56 
57 	uchar reg_a;
58 
59 	reg_a = rtc_read( RTC_CONTROLA );
60 	/* lock clock registers for read */
61 	rtc_write( RTC_CONTROLA, ( reg_a | RTC_CA_READ ));
62 
63 	sec     = rtc_read( RTC_SECONDS );
64 	min     = rtc_read( RTC_MINUTES );
65 	hour    = rtc_read( RTC_HOURS );
66 	mday    = rtc_read( RTC_DAY_OF_MONTH );
67 	wday    = rtc_read( RTC_DAY_OF_WEEK );
68 	mon     = rtc_read( RTC_MONTH );
69 	year    = rtc_read( RTC_YEAR );
70 	century = rtc_read( RTC_CENTURY );
71 
72 	/* unlock clock registers after read */
73 	rtc_write( RTC_CONTROLA, ( reg_a & ~RTC_CA_READ ));
74 
75 #ifdef RTC_DEBUG
76 	printf( "Get RTC year: %02x mon/cent: %02x mday: %02x wday: %02x "
77 		"hr: %02x min: %02x sec: %02x\n",
78 		year, mon_cent, mday, wday,
79 		hour, min, sec );
80 #endif
81 	tmp->tm_sec  = bcd2bin( sec  & 0x7F );
82 	tmp->tm_min  = bcd2bin( min  & 0x7F );
83 	tmp->tm_hour = bcd2bin( hour & 0x3F );
84 	tmp->tm_mday = bcd2bin( mday & 0x3F );
85 	tmp->tm_mon  = bcd2bin( mon & 0x1F );
86 	tmp->tm_wday = bcd2bin( wday & 0x07 );
87 
88 	/* glue year from century and year in century */
89 	tmp->tm_year = bcd2bin( year ) +
90 		( bcd2bin( century & 0x3F ) * 100 );
91 
92 	tmp->tm_yday = 0;
93 	tmp->tm_isdst= 0;
94 #ifdef RTC_DEBUG
95 	printf( "Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
96 		tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
97 		tmp->tm_hour, tmp->tm_min, tmp->tm_sec );
98 #endif
99 	return 0;
100 }
101 
102 int rtc_set( struct rtc_time *tmp )
103 {
104 	uchar reg_a;
105 #ifdef RTC_DEBUG
106 	printf( "Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
107 		tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
108 		tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
109 #endif
110 	/* lock clock registers for write */
111 	reg_a = rtc_read( RTC_CONTROLA );
112 	rtc_write( RTC_CONTROLA, ( reg_a | RTC_CA_WRITE ));
113 
114 	rtc_write( RTC_MONTH, bin2bcd( tmp->tm_mon ));
115 
116 	rtc_write( RTC_DAY_OF_WEEK, bin2bcd( tmp->tm_wday ));
117 	rtc_write( RTC_DAY_OF_MONTH, bin2bcd( tmp->tm_mday ));
118 	rtc_write( RTC_HOURS, bin2bcd( tmp->tm_hour ));
119 	rtc_write( RTC_MINUTES, bin2bcd( tmp->tm_min ));
120 	rtc_write( RTC_SECONDS, bin2bcd( tmp->tm_sec ));
121 
122 	/* break year up into century and year in century */
123 	rtc_write( RTC_YEAR, bin2bcd( tmp->tm_year % 100 ));
124 	rtc_write( RTC_CENTURY, bin2bcd( tmp->tm_year / 100 ));
125 
126 	/* unlock clock registers after read */
127 	rtc_write( RTC_CONTROLA, ( reg_a  & ~RTC_CA_WRITE ));
128 
129 	return 0;
130 }
131 
132 void rtc_reset (void)
133 {
134 	uchar reg_a, reg_b, reg_c;
135 
136 	reg_a = rtc_read( RTC_CONTROLA );
137 	reg_b = rtc_read( RTC_CONTROLB );
138 
139 	if ( reg_b & RTC_CB_OSC_DISABLE )
140 	{
141 		printf( "real-time-clock was stopped. Now starting...\n" );
142 		reg_a |= RTC_CA_WRITE;
143 		reg_b &= ~RTC_CB_OSC_DISABLE;
144 
145 		rtc_write( RTC_CONTROLA, reg_a );
146 		rtc_write( RTC_CONTROLB, reg_b );
147 	}
148 
149 	/* make sure read/write clock register bits are cleared */
150 	reg_a &= ~( RTC_CA_WRITE | RTC_CA_READ );
151 	rtc_write( RTC_CONTROLA, reg_a );
152 
153 	reg_c = rtc_read( RTC_CONTROLC );
154 	if (( reg_c & RTC_CC_BATTERY_FLAG ) == 0 )
155 		printf( "RTC battery low. Clock setting may not be reliable.\n" );
156 }
157 
158 /* ------------------------------------------------------------------------- */
159 
160 static uchar rtc_read( unsigned int addr )
161 {
162 	uchar val = in8( addr );
163 #ifdef RTC_DEBUG
164 	printf( "rtc_read: %x:%x\n", addr, val );
165 #endif
166 	return( val );
167 }
168 
169 static void rtc_write( unsigned int addr, uchar val )
170 {
171 #ifdef RTC_DEBUG
172 	printf( "rtc_write: %x:%x\n", addr, val );
173 #endif
174 	out8( addr, val );
175 }
176 
177 #endif
178