summaryrefslogtreecommitdiff
path: root/drivers/rtc/m41t60.c
blob: 7846193e260d7cc0d4ffce62643f76173c46737e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
// SPDX-License-Identifier: GPL-2.0+
/*
 * (C) Copyright 2007
 * Larry Johnson, lrj@acm.org
 *
 * based on rtc/m41t11.c which is ...
 *
 * (C) Copyright 2002
 * Andrew May, Viasat Inc, amay@viasat.com
 */

/*
 * STMicroelectronics M41T60 serial access real-time clock
 */

/* #define DEBUG 1 */

#include <common.h>
#include <command.h>
#include <rtc.h>
#include <i2c.h>

#if defined(CONFIG_SYS_I2C_RTC_ADDR) && defined(CONFIG_CMD_DATE)

/*
 * Convert between century and "century bits" (CB1 and CB0).  These routines
 * assume years are in the range 1900 - 2299.
 */

static unsigned char year2cb(unsigned const year)
{
	if (year < 1900 || year >= 2300)
		printf("M41T60 RTC: year %d out of range\n", year);

	return (year / 100) & 0x3;
}

static unsigned cb2year(unsigned const cb)
{
	return 1900 + 100 * ((cb + 1) & 0x3);
}

/*
 * These are simple defines for the chip local to here so they aren't too
 * verbose.  DAY/DATE aren't nice but that is how they are on the data sheet.
 */
#define RTC_SEC		0x0
#define RTC_MIN		0x1
#define RTC_HOUR	0x2
#define RTC_DAY		0x3
#define RTC_DATE	0x4
#define RTC_MONTH	0x5
#define RTC_YEAR	0x6

#define RTC_REG_CNT	7

#define RTC_CTRL	0x7

#if defined(DEBUG)
static void rtc_dump(char const *const label)
{
	uchar data[8];

	if (i2c_read(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
		printf("I2C read failed in rtc_dump()\n");
		return;
	}
	printf("RTC dump %s: %02X-%02X-%02X-%02X-%02X-%02X-%02X-%02X\n",
	       label, data[0], data[1], data[2], data[3],
	       data[4], data[5], data[6], data[7]);
}
#else
#define rtc_dump(label)
#endif

static uchar *rtc_validate(void)
{
	/*
	 * This routine uses the OUT bit and the validity of the time values to
	 * determine whether there has been an initial power-up since the last
	 * time the routine was run.  It assumes that the OUT bit is not being
	 * used for any other purpose.
	 */
	static const uchar daysInMonth[0x13] = {
		0x00, 0x31, 0x29, 0x31, 0x30, 0x31, 0x30, 0x31,
		0x31, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x31, 0x30, 0x31
	};
	static uchar data[8];
	uchar min, date, month, years;

	rtc_dump("begin validate");
	if (i2c_read(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
		printf("I2C read failed in rtc_validate()\n");
		return 0;
	}
	/*
	 * If the OUT bit is "1", there has been a loss of power, so stop the
	 * oscillator so it can be "kick-started" as per data sheet.
	 */
	if (0x00 != (data[RTC_CTRL] & 0x80)) {
		printf("M41T60 RTC clock lost power.\n");
		data[RTC_SEC] = 0x80;
		if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, RTC_SEC, 1, data, 1)) {
			printf("I2C write failed in rtc_validate()\n");
			return 0;
		}
	}
	/*
	 * If the oscillator is stopped or the date is invalid, then reset the
	 * OUT bit to "0", reset the date registers, and start the oscillator.
	 */
	min = data[RTC_MIN] & 0x7F;
	date = data[RTC_DATE];
	month = data[RTC_MONTH] & 0x3F;
	years = data[RTC_YEAR];
	if (0x59 < data[RTC_SEC] || 0x09 < (data[RTC_SEC] & 0x0F) ||
	    0x59 < min || 0x09 < (min & 0x0F) ||
	    0x23 < data[RTC_HOUR] || 0x09 < (data[RTC_HOUR] & 0x0F) ||
	    0x07 < data[RTC_DAY] || 0x00 == data[RTC_DAY] ||
	    0x12 < month ||
	    0x99 < years || 0x09 < (years & 0x0F) ||
	    daysInMonth[month] < date || 0x09 < (date & 0x0F) || 0x00 == date ||
	    (0x29 == date && 0x02 == month &&
	     ((0x00 != (years & 0x03)) ||
	      (0x00 == years && 0x00 != (data[RTC_MONTH] & 0xC0))))) {
		printf("Resetting M41T60 RTC clock.\n");
		/*
		 * Set to 00:00:00 1900-01-01 (Monday)
		 */
		data[RTC_SEC] = 0x00;
		data[RTC_MIN] &= 0x80;	/* preserve OFIE bit */
		data[RTC_HOUR] = 0x00;
		data[RTC_DAY] = 0x02;
		data[RTC_DATE] = 0x01;
		data[RTC_MONTH] = 0xC1;
		data[RTC_YEAR] = 0x00;
		data[RTC_CTRL] &= 0x7F;	/* reset OUT bit */

		if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
			printf("I2C write failed in rtc_validate()\n");
			return 0;
		}
	}
	return data;
}

int rtc_get(struct rtc_time *tmp)
{
	uchar const *const data = rtc_validate();

	if (!data)
		return -1;

	tmp->tm_sec = bcd2bin(data[RTC_SEC] & 0x7F);
	tmp->tm_min = bcd2bin(data[RTC_MIN] & 0x7F);
	tmp->tm_hour = bcd2bin(data[RTC_HOUR] & 0x3F);
	tmp->tm_mday = bcd2bin(data[RTC_DATE] & 0x3F);
	tmp->tm_mon = bcd2bin(data[RTC_MONTH] & 0x1F);
	tmp->tm_year = cb2year(data[RTC_MONTH] >> 6) + bcd2bin(data[RTC_YEAR]);
	tmp->tm_wday = bcd2bin(data[RTC_DAY] & 0x07) - 1;
	tmp->tm_yday = 0;
	tmp->tm_isdst = 0;

	debug("Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
	      tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
	      tmp->tm_hour, tmp->tm_min, tmp->tm_sec);

	return 0;
}

int rtc_set(struct rtc_time *tmp)
{
	uchar *const data = rtc_validate();

	if (!data)
		return -1;

	debug("Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
	      tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
	      tmp->tm_hour, tmp->tm_min, tmp->tm_sec);

	data[RTC_SEC] = (data[RTC_SEC] & 0x80) | (bin2bcd(tmp->tm_sec) & 0x7F);
	data[RTC_MIN] = (data[RTC_MIN] & 0X80) | (bin2bcd(tmp->tm_min) & 0X7F);
	data[RTC_HOUR] = bin2bcd(tmp->tm_hour) & 0x3F;
	data[RTC_DATE] = bin2bcd(tmp->tm_mday) & 0x3F;
	data[RTC_MONTH] = bin2bcd(tmp->tm_mon) & 0x1F;
	data[RTC_YEAR] = bin2bcd(tmp->tm_year % 100);
	data[RTC_MONTH] |= year2cb(tmp->tm_year) << 6;
	data[RTC_DAY] = bin2bcd(tmp->tm_wday + 1) & 0x07;
	if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, RTC_REG_CNT)) {
		printf("I2C write failed in rtc_set()\n");
		return -1;
	}

	return 0;
}

void rtc_reset(void)
{
	uchar *const data = rtc_validate();
	char const *const s = env_get("rtccal");

	if (!data)
		return;

	rtc_dump("begin reset");
	/*
	 * If environmental variable "rtccal" is present, it must be a hex value
	 * between 0x00 and 0x3F, inclusive.  The five least-significan bits
	 * represent the calibration magnitude, and the sixth bit the sign bit.
	 * If these do not match the contents of the hardware register, that
	 * register is updated.  The value 0x00 imples no correction.  Consult
	 * the M41T60 documentation for further details.
	 */
	if (s) {
		unsigned long const l = simple_strtoul(s, 0, 16);

		if (l <= 0x3F) {
			if ((data[RTC_CTRL] & 0x3F) != l) {
				printf("Setting RTC calibration to 0x%02lX\n",
				       l);
				data[RTC_CTRL] &= 0xC0;
				data[RTC_CTRL] |= (uchar) l;
			}
		} else
			printf("environment parameter \"rtccal\" not valid: "
			       "ignoring\n");
	}
	/*
	 * Turn off frequency test.
	 */
	data[RTC_CTRL] &= 0xBF;
	if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, RTC_CTRL, 1, data + RTC_CTRL, 1)) {
		printf("I2C write failed in rtc_reset()\n");
		return;
	}
	rtc_dump("end reset");
}
#endif /* CONFIG_RTC_M41T60 && CONFIG_SYS_I2C_RTC_ADDR && CONFIG_CMD_DATE */