xref: /openbmc/u-boot/drivers/rtc/m41t60.c (revision fc82e768)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * (C) Copyright 2007
4  * Larry Johnson, lrj@acm.org
5  *
6  * based on rtc/m41t11.c which is ...
7  *
8  * (C) Copyright 2002
9  * Andrew May, Viasat Inc, amay@viasat.com
10  */
11 
12 /*
13  * STMicroelectronics M41T60 serial access real-time clock
14  */
15 
16 /* #define DEBUG 1 */
17 
18 #include <common.h>
19 #include <command.h>
20 #include <rtc.h>
21 #include <i2c.h>
22 
23 /*
24  * Convert between century and "century bits" (CB1 and CB0).  These routines
25  * assume years are in the range 1900 - 2299.
26  */
27 
year2cb(unsigned const year)28 static unsigned char year2cb(unsigned const year)
29 {
30 	if (year < 1900 || year >= 2300)
31 		printf("M41T60 RTC: year %d out of range\n", year);
32 
33 	return (year / 100) & 0x3;
34 }
35 
cb2year(unsigned const cb)36 static unsigned cb2year(unsigned const cb)
37 {
38 	return 1900 + 100 * ((cb + 1) & 0x3);
39 }
40 
41 /*
42  * These are simple defines for the chip local to here so they aren't too
43  * verbose.  DAY/DATE aren't nice but that is how they are on the data sheet.
44  */
45 #define RTC_SEC		0x0
46 #define RTC_MIN		0x1
47 #define RTC_HOUR	0x2
48 #define RTC_DAY		0x3
49 #define RTC_DATE	0x4
50 #define RTC_MONTH	0x5
51 #define RTC_YEAR	0x6
52 
53 #define RTC_REG_CNT	7
54 
55 #define RTC_CTRL	0x7
56 
57 #if defined(DEBUG)
rtc_dump(char const * const label)58 static void rtc_dump(char const *const label)
59 {
60 	uchar data[8];
61 
62 	if (i2c_read(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
63 		printf("I2C read failed in rtc_dump()\n");
64 		return;
65 	}
66 	printf("RTC dump %s: %02X-%02X-%02X-%02X-%02X-%02X-%02X-%02X\n",
67 	       label, data[0], data[1], data[2], data[3],
68 	       data[4], data[5], data[6], data[7]);
69 }
70 #else
71 #define rtc_dump(label)
72 #endif
73 
rtc_validate(void)74 static uchar *rtc_validate(void)
75 {
76 	/*
77 	 * This routine uses the OUT bit and the validity of the time values to
78 	 * determine whether there has been an initial power-up since the last
79 	 * time the routine was run.  It assumes that the OUT bit is not being
80 	 * used for any other purpose.
81 	 */
82 	static const uchar daysInMonth[0x13] = {
83 		0x00, 0x31, 0x29, 0x31, 0x30, 0x31, 0x30, 0x31,
84 		0x31, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
85 		0x31, 0x30, 0x31
86 	};
87 	static uchar data[8];
88 	uchar min, date, month, years;
89 
90 	rtc_dump("begin validate");
91 	if (i2c_read(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
92 		printf("I2C read failed in rtc_validate()\n");
93 		return 0;
94 	}
95 	/*
96 	 * If the OUT bit is "1", there has been a loss of power, so stop the
97 	 * oscillator so it can be "kick-started" as per data sheet.
98 	 */
99 	if (0x00 != (data[RTC_CTRL] & 0x80)) {
100 		printf("M41T60 RTC clock lost power.\n");
101 		data[RTC_SEC] = 0x80;
102 		if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, RTC_SEC, 1, data, 1)) {
103 			printf("I2C write failed in rtc_validate()\n");
104 			return 0;
105 		}
106 	}
107 	/*
108 	 * If the oscillator is stopped or the date is invalid, then reset the
109 	 * OUT bit to "0", reset the date registers, and start the oscillator.
110 	 */
111 	min = data[RTC_MIN] & 0x7F;
112 	date = data[RTC_DATE];
113 	month = data[RTC_MONTH] & 0x3F;
114 	years = data[RTC_YEAR];
115 	if (0x59 < data[RTC_SEC] || 0x09 < (data[RTC_SEC] & 0x0F) ||
116 	    0x59 < min || 0x09 < (min & 0x0F) ||
117 	    0x23 < data[RTC_HOUR] || 0x09 < (data[RTC_HOUR] & 0x0F) ||
118 	    0x07 < data[RTC_DAY] || 0x00 == data[RTC_DAY] ||
119 	    0x12 < month ||
120 	    0x99 < years || 0x09 < (years & 0x0F) ||
121 	    daysInMonth[month] < date || 0x09 < (date & 0x0F) || 0x00 == date ||
122 	    (0x29 == date && 0x02 == month &&
123 	     ((0x00 != (years & 0x03)) ||
124 	      (0x00 == years && 0x00 != (data[RTC_MONTH] & 0xC0))))) {
125 		printf("Resetting M41T60 RTC clock.\n");
126 		/*
127 		 * Set to 00:00:00 1900-01-01 (Monday)
128 		 */
129 		data[RTC_SEC] = 0x00;
130 		data[RTC_MIN] &= 0x80;	/* preserve OFIE bit */
131 		data[RTC_HOUR] = 0x00;
132 		data[RTC_DAY] = 0x02;
133 		data[RTC_DATE] = 0x01;
134 		data[RTC_MONTH] = 0xC1;
135 		data[RTC_YEAR] = 0x00;
136 		data[RTC_CTRL] &= 0x7F;	/* reset OUT bit */
137 
138 		if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
139 			printf("I2C write failed in rtc_validate()\n");
140 			return 0;
141 		}
142 	}
143 	return data;
144 }
145 
rtc_get(struct rtc_time * tmp)146 int rtc_get(struct rtc_time *tmp)
147 {
148 	uchar const *const data = rtc_validate();
149 
150 	if (!data)
151 		return -1;
152 
153 	tmp->tm_sec = bcd2bin(data[RTC_SEC] & 0x7F);
154 	tmp->tm_min = bcd2bin(data[RTC_MIN] & 0x7F);
155 	tmp->tm_hour = bcd2bin(data[RTC_HOUR] & 0x3F);
156 	tmp->tm_mday = bcd2bin(data[RTC_DATE] & 0x3F);
157 	tmp->tm_mon = bcd2bin(data[RTC_MONTH] & 0x1F);
158 	tmp->tm_year = cb2year(data[RTC_MONTH] >> 6) + bcd2bin(data[RTC_YEAR]);
159 	tmp->tm_wday = bcd2bin(data[RTC_DAY] & 0x07) - 1;
160 	tmp->tm_yday = 0;
161 	tmp->tm_isdst = 0;
162 
163 	debug("Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
164 	      tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
165 	      tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
166 
167 	return 0;
168 }
169 
rtc_set(struct rtc_time * tmp)170 int rtc_set(struct rtc_time *tmp)
171 {
172 	uchar *const data = rtc_validate();
173 
174 	if (!data)
175 		return -1;
176 
177 	debug("Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
178 	      tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
179 	      tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
180 
181 	data[RTC_SEC] = (data[RTC_SEC] & 0x80) | (bin2bcd(tmp->tm_sec) & 0x7F);
182 	data[RTC_MIN] = (data[RTC_MIN] & 0X80) | (bin2bcd(tmp->tm_min) & 0X7F);
183 	data[RTC_HOUR] = bin2bcd(tmp->tm_hour) & 0x3F;
184 	data[RTC_DATE] = bin2bcd(tmp->tm_mday) & 0x3F;
185 	data[RTC_MONTH] = bin2bcd(tmp->tm_mon) & 0x1F;
186 	data[RTC_YEAR] = bin2bcd(tmp->tm_year % 100);
187 	data[RTC_MONTH] |= year2cb(tmp->tm_year) << 6;
188 	data[RTC_DAY] = bin2bcd(tmp->tm_wday + 1) & 0x07;
189 	if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, RTC_REG_CNT)) {
190 		printf("I2C write failed in rtc_set()\n");
191 		return -1;
192 	}
193 
194 	return 0;
195 }
196 
rtc_reset(void)197 void rtc_reset(void)
198 {
199 	uchar *const data = rtc_validate();
200 	char const *const s = env_get("rtccal");
201 
202 	if (!data)
203 		return;
204 
205 	rtc_dump("begin reset");
206 	/*
207 	 * If environmental variable "rtccal" is present, it must be a hex value
208 	 * between 0x00 and 0x3F, inclusive.  The five least-significan bits
209 	 * represent the calibration magnitude, and the sixth bit the sign bit.
210 	 * If these do not match the contents of the hardware register, that
211 	 * register is updated.  The value 0x00 imples no correction.  Consult
212 	 * the M41T60 documentation for further details.
213 	 */
214 	if (s) {
215 		unsigned long const l = simple_strtoul(s, 0, 16);
216 
217 		if (l <= 0x3F) {
218 			if ((data[RTC_CTRL] & 0x3F) != l) {
219 				printf("Setting RTC calibration to 0x%02lX\n",
220 				       l);
221 				data[RTC_CTRL] &= 0xC0;
222 				data[RTC_CTRL] |= (uchar) l;
223 			}
224 		} else
225 			printf("environment parameter \"rtccal\" not valid: "
226 			       "ignoring\n");
227 	}
228 	/*
229 	 * Turn off frequency test.
230 	 */
231 	data[RTC_CTRL] &= 0xBF;
232 	if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, RTC_CTRL, 1, data + RTC_CTRL, 1)) {
233 		printf("I2C write failed in rtc_reset()\n");
234 		return;
235 	}
236 	rtc_dump("end reset");
237 }
238