--- /dev/null
+/*
+ * (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
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+/*
+ * 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 = getenv("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 */
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