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