diff options
Diffstat (limited to 'drivers/rtc/m41t60.c')
| -rw-r--r-- | drivers/rtc/m41t60.c | 261 |
1 files changed, 261 insertions, 0 deletions
diff --git a/drivers/rtc/m41t60.c b/drivers/rtc/m41t60.c new file mode 100644 index 0000000..7c80143 --- /dev/null +++ b/drivers/rtc/m41t60.c @@ -0,0 +1,261 @@ +/* + * (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 + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of + * the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, + * MA 02111-1307 USA + */ + +/* + * 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_RTC_M41T60) && defined(CFG_I2C_RTC_ADDR) && \ + defined(CONFIG_CMD_DATE) + +static unsigned bcd2bin(uchar n) +{ + return ((((n >> 4) & 0x0F) * 10) + (n & 0x0F)); +} + +static unsigned char bin2bcd(unsigned int n) +{ + return (((n / 10) << 4) | (n % 10)); +} + +/* + * 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(CFG_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(CFG_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(CFG_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(CFG_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) { + printf("I2C write failed in rtc_validate()\n"); + return 0; + } + } + return data; +} + +void rtc_get(struct rtc_time *tmp) +{ + uchar const *const data = rtc_validate(); + + if (!data) + return; + + 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); +} + +void rtc_set(struct rtc_time *tmp) +{ + uchar *const data = rtc_validate(); + + if (!data) + return; + + 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(CFG_I2C_RTC_ADDR, 0, 1, data, RTC_REG_CNT)) { + printf("I2C write failed in rtc_set()\n"); + return; + } +} + +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%02X\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(CFG_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 && CFG_I2C_RTC_ADDR && CONFIG_CMD_DATE */ |