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 <env.h>
21 #include <log.h>
22 #include <rtc.h>
23 #include <i2c.h>
24
25 /*
26 * Convert between century and "century bits" (CB1 and CB0). These routines
27 * assume years are in the range 1900 - 2299.
28 */
29
year2cb(unsigned const year)30 static unsigned char year2cb(unsigned const year)
31 {
32 if (year < 1900 || year >= 2300)
33 printf("M41T60 RTC: year %d out of range\n", year);
34
35 return (year / 100) & 0x3;
36 }
37
cb2year(unsigned const cb)38 static unsigned cb2year(unsigned const cb)
39 {
40 return 1900 + 100 * ((cb + 1) & 0x3);
41 }
42
43 /*
44 * These are simple defines for the chip local to here so they aren't too
45 * verbose. DAY/DATE aren't nice but that is how they are on the data sheet.
46 */
47 #define RTC_SEC 0x0
48 #define RTC_MIN 0x1
49 #define RTC_HOUR 0x2
50 #define RTC_DAY 0x3
51 #define RTC_DATE 0x4
52 #define RTC_MONTH 0x5
53 #define RTC_YEAR 0x6
54
55 #define RTC_REG_CNT 7
56
57 #define RTC_CTRL 0x7
58
59 #if defined(DEBUG)
rtc_dump(char const * const label)60 static void rtc_dump(char const *const label)
61 {
62 uchar data[8];
63
64 if (i2c_read(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
65 printf("I2C read failed in rtc_dump()\n");
66 return;
67 }
68 printf("RTC dump %s: %02X-%02X-%02X-%02X-%02X-%02X-%02X-%02X\n",
69 label, data[0], data[1], data[2], data[3],
70 data[4], data[5], data[6], data[7]);
71 }
72 #else
73 #define rtc_dump(label)
74 #endif
75
rtc_validate(void)76 static uchar *rtc_validate(void)
77 {
78 /*
79 * This routine uses the OUT bit and the validity of the time values to
80 * determine whether there has been an initial power-up since the last
81 * time the routine was run. It assumes that the OUT bit is not being
82 * used for any other purpose.
83 */
84 static const uchar daysInMonth[0x13] = {
85 0x00, 0x31, 0x29, 0x31, 0x30, 0x31, 0x30, 0x31,
86 0x31, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
87 0x31, 0x30, 0x31
88 };
89 static uchar data[8];
90 uchar min, date, month, years;
91
92 rtc_dump("begin validate");
93 if (i2c_read(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
94 printf("I2C read failed in rtc_validate()\n");
95 return 0;
96 }
97 /*
98 * If the OUT bit is "1", there has been a loss of power, so stop the
99 * oscillator so it can be "kick-started" as per data sheet.
100 */
101 if (0x00 != (data[RTC_CTRL] & 0x80)) {
102 printf("M41T60 RTC clock lost power.\n");
103 data[RTC_SEC] = 0x80;
104 if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, RTC_SEC, 1, data, 1)) {
105 printf("I2C write failed in rtc_validate()\n");
106 return 0;
107 }
108 }
109 /*
110 * If the oscillator is stopped or the date is invalid, then reset the
111 * OUT bit to "0", reset the date registers, and start the oscillator.
112 */
113 min = data[RTC_MIN] & 0x7F;
114 date = data[RTC_DATE];
115 month = data[RTC_MONTH] & 0x3F;
116 years = data[RTC_YEAR];
117 if (0x59 < data[RTC_SEC] || 0x09 < (data[RTC_SEC] & 0x0F) ||
118 0x59 < min || 0x09 < (min & 0x0F) ||
119 0x23 < data[RTC_HOUR] || 0x09 < (data[RTC_HOUR] & 0x0F) ||
120 0x07 < data[RTC_DAY] || 0x00 == data[RTC_DAY] ||
121 0x12 < month ||
122 0x99 < years || 0x09 < (years & 0x0F) ||
123 daysInMonth[month] < date || 0x09 < (date & 0x0F) || 0x00 == date ||
124 (0x29 == date && 0x02 == month &&
125 ((0x00 != (years & 0x03)) ||
126 (0x00 == years && 0x00 != (data[RTC_MONTH] & 0xC0))))) {
127 printf("Resetting M41T60 RTC clock.\n");
128 /*
129 * Set to 00:00:00 1900-01-01 (Monday)
130 */
131 data[RTC_SEC] = 0x00;
132 data[RTC_MIN] &= 0x80; /* preserve OFIE bit */
133 data[RTC_HOUR] = 0x00;
134 data[RTC_DAY] = 0x02;
135 data[RTC_DATE] = 0x01;
136 data[RTC_MONTH] = 0xC1;
137 data[RTC_YEAR] = 0x00;
138 data[RTC_CTRL] &= 0x7F; /* reset OUT bit */
139
140 if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
141 printf("I2C write failed in rtc_validate()\n");
142 return 0;
143 }
144 }
145 return data;
146 }
147
rtc_get(struct rtc_time * tmp)148 int rtc_get(struct rtc_time *tmp)
149 {
150 uchar const *const data = rtc_validate();
151
152 if (!data)
153 return -1;
154
155 tmp->tm_sec = bcd2bin(data[RTC_SEC] & 0x7F);
156 tmp->tm_min = bcd2bin(data[RTC_MIN] & 0x7F);
157 tmp->tm_hour = bcd2bin(data[RTC_HOUR] & 0x3F);
158 tmp->tm_mday = bcd2bin(data[RTC_DATE] & 0x3F);
159 tmp->tm_mon = bcd2bin(data[RTC_MONTH] & 0x1F);
160 tmp->tm_year = cb2year(data[RTC_MONTH] >> 6) + bcd2bin(data[RTC_YEAR]);
161 tmp->tm_wday = bcd2bin(data[RTC_DAY] & 0x07) - 1;
162 tmp->tm_yday = 0;
163 tmp->tm_isdst = 0;
164
165 debug("Get DATE: %4d-%02d-%02d (wday=%d) TIME: %2d:%02d:%02d\n",
166 tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
167 tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
168
169 return 0;
170 }
171
rtc_set(struct rtc_time * tmp)172 int rtc_set(struct rtc_time *tmp)
173 {
174 uchar *const data = rtc_validate();
175
176 if (!data)
177 return -1;
178
179 debug("Set DATE: %4d-%02d-%02d (wday=%d) TIME: %2d:%02d:%02d\n",
180 tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
181 tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
182
183 data[RTC_SEC] = (data[RTC_SEC] & 0x80) | (bin2bcd(tmp->tm_sec) & 0x7F);
184 data[RTC_MIN] = (data[RTC_MIN] & 0X80) | (bin2bcd(tmp->tm_min) & 0X7F);
185 data[RTC_HOUR] = bin2bcd(tmp->tm_hour) & 0x3F;
186 data[RTC_DATE] = bin2bcd(tmp->tm_mday) & 0x3F;
187 data[RTC_MONTH] = bin2bcd(tmp->tm_mon) & 0x1F;
188 data[RTC_YEAR] = bin2bcd(tmp->tm_year % 100);
189 data[RTC_MONTH] |= year2cb(tmp->tm_year) << 6;
190 data[RTC_DAY] = bin2bcd(tmp->tm_wday + 1) & 0x07;
191 if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, RTC_REG_CNT)) {
192 printf("I2C write failed in rtc_set()\n");
193 return -1;
194 }
195
196 return 0;
197 }
198
rtc_reset(void)199 void rtc_reset(void)
200 {
201 uchar *const data = rtc_validate();
202 char const *const s = env_get("rtccal");
203
204 if (!data)
205 return;
206
207 rtc_dump("begin reset");
208 /*
209 * If environmental variable "rtccal" is present, it must be a hex value
210 * between 0x00 and 0x3F, inclusive. The five least-significan bits
211 * represent the calibration magnitude, and the sixth bit the sign bit.
212 * If these do not match the contents of the hardware register, that
213 * register is updated. The value 0x00 imples no correction. Consult
214 * the M41T60 documentation for further details.
215 */
216 if (s) {
217 unsigned long const l = simple_strtoul(s, 0, 16);
218
219 if (l <= 0x3F) {
220 if ((data[RTC_CTRL] & 0x3F) != l) {
221 printf("Setting RTC calibration to 0x%02lX\n",
222 l);
223 data[RTC_CTRL] &= 0xC0;
224 data[RTC_CTRL] |= (uchar) l;
225 }
226 } else
227 printf("environment parameter \"rtccal\" not valid: "
228 "ignoring\n");
229 }
230 /*
231 * Turn off frequency test.
232 */
233 data[RTC_CTRL] &= 0xBF;
234 if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, RTC_CTRL, 1, data + RTC_CTRL, 1)) {
235 printf("I2C write failed in rtc_reset()\n");
236 return;
237 }
238 rtc_dump("end reset");
239 }
240