1 // SPDX-License-Identifier: GPL-2.0+
4 * Larry Johnson, lrj@acm.org
6 * based on rtc/m41t11.c which is ...
9 * Andrew May, Viasat Inc, amay@viasat.com
13 * STMicroelectronics M41T60 serial access real-time clock
23 #if defined(CONFIG_SYS_I2C_RTC_ADDR) && defined(CONFIG_CMD_DATE)
26 * Convert between century and "century bits" (CB1 and CB0). These routines
27 * assume years are in the range 1900 - 2299.
30 static unsigned char year2cb(unsigned const year)
32 if (year < 1900 || year >= 2300)
33 printf("M41T60 RTC: year %d out of range\n", year);
35 return (year / 100) & 0x3;
38 static unsigned cb2year(unsigned const cb)
40 return 1900 + 100 * ((cb + 1) & 0x3);
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.
60 static void rtc_dump(char const *const label)
64 if (i2c_read(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
65 printf("I2C read failed in rtc_dump()\n");
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]);
73 #define rtc_dump(label)
76 static uchar *rtc_validate(void)
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.
84 static const uchar daysInMonth[0x13] = {
85 0x00, 0x31, 0x29, 0x31, 0x30, 0x31, 0x30, 0x31,
86 0x31, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
90 uchar min, date, month, years;
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");
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.
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");
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.
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] ||
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");
129 * Set to 00:00:00 1900-01-01 (Monday)
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 */
140 if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
141 printf("I2C write failed in rtc_validate()\n");
148 int rtc_get(struct rtc_time *tmp)
150 uchar const *const data = rtc_validate();
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;
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);
172 int rtc_set(struct rtc_time *tmp)
174 uchar *const data = rtc_validate();
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);
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");
201 uchar *const data = rtc_validate();
202 char const *const s = env_get("rtccal");
207 rtc_dump("begin reset");
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.
217 unsigned long const l = simple_strtoul(s, 0, 16);
220 if ((data[RTC_CTRL] & 0x3F) != l) {
221 printf("Setting RTC calibration to 0x%02lX\n",
223 data[RTC_CTRL] &= 0xC0;
224 data[RTC_CTRL] |= (uchar) l;
227 printf("environment parameter \"rtccal\" not valid: "
231 * Turn off frequency test.
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");
238 rtc_dump("end reset");
240 #endif /* CONFIG_RTC_M41T60 && CONFIG_SYS_I2C_RTC_ADDR && CONFIG_CMD_DATE */