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Diffstat (limited to 'rtc/ds3231.c')
| -rw-r--r-- | rtc/ds3231.c | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/rtc/ds3231.c b/rtc/ds3231.c new file mode 100644 index 0000000..50aeeb5 --- /dev/null +++ b/rtc/ds3231.c @@ -0,0 +1,193 @@ +/* + * (C) Copyright 2006 + * Markus Klotzbuecher, mk@denx.de + * + * See file CREDITS for list of people who contributed to this + * project. + * + * 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 + */ + +/* + * Date & Time support (no alarms) for Dallas Semiconductor (now Maxim) + * Extremly Accurate DS3231 Real Time Clock (RTC). + * + * copied from ds1337.c + */ + +#include <common.h> +#include <command.h> +#include <rtc.h> +#include <i2c.h> + +#if defined(CONFIG_RTC_DS3231) && (CONFIG_COMMANDS & CFG_CMD_DATE) + +/*---------------------------------------------------------------------*/ +#undef DEBUG_RTC + +#ifdef DEBUG_RTC +#define DEBUGR(fmt,args...) printf(fmt ,##args) +#else +#define DEBUGR(fmt,args...) +#endif +/*---------------------------------------------------------------------*/ + +/* + * RTC register addresses + */ +#define RTC_SEC_REG_ADDR 0x0 +#define RTC_MIN_REG_ADDR 0x1 +#define RTC_HR_REG_ADDR 0x2 +#define RTC_DAY_REG_ADDR 0x3 +#define RTC_DATE_REG_ADDR 0x4 +#define RTC_MON_REG_ADDR 0x5 +#define RTC_YR_REG_ADDR 0x6 +#define RTC_CTL_REG_ADDR 0x0e +#define RTC_STAT_REG_ADDR 0x0f + + +/* + * RTC control register bits + */ +#define RTC_CTL_BIT_A1IE 0x1 /* Alarm 1 interrupt enable */ +#define RTC_CTL_BIT_A2IE 0x2 /* Alarm 2 interrupt enable */ +#define RTC_CTL_BIT_INTCN 0x4 /* Interrupt control */ +#define RTC_CTL_BIT_RS1 0x8 /* Rate select 1 */ +#define RTC_CTL_BIT_RS2 0x10 /* Rate select 2 */ +#define RTC_CTL_BIT_DOSC 0x80 /* Disable Oscillator */ + +/* + * RTC status register bits + */ +#define RTC_STAT_BIT_A1F 0x1 /* Alarm 1 flag */ +#define RTC_STAT_BIT_A2F 0x2 /* Alarm 2 flag */ +#define RTC_STAT_BIT_OSF 0x80 /* Oscillator stop flag */ + + +static uchar rtc_read (uchar reg); +static void rtc_write (uchar reg, uchar val); +static uchar bin2bcd (unsigned int n); +static unsigned bcd2bin (uchar c); + + +/* + * Get the current time from the RTC + */ +void rtc_get (struct rtc_time *tmp) +{ + uchar sec, min, hour, mday, wday, mon_cent, year, control, status; + + control = rtc_read (RTC_CTL_REG_ADDR); + status = rtc_read (RTC_STAT_REG_ADDR); + sec = rtc_read (RTC_SEC_REG_ADDR); + min = rtc_read (RTC_MIN_REG_ADDR); + hour = rtc_read (RTC_HR_REG_ADDR); + wday = rtc_read (RTC_DAY_REG_ADDR); + mday = rtc_read (RTC_DATE_REG_ADDR); + mon_cent = rtc_read (RTC_MON_REG_ADDR); + year = rtc_read (RTC_YR_REG_ADDR); + + DEBUGR ("Get RTC year: %02x mon/cent: %02x mday: %02x wday: %02x " + "hr: %02x min: %02x sec: %02x control: %02x status: %02x\n", + year, mon_cent, mday, wday, hour, min, sec, control, status); + + if (status & RTC_STAT_BIT_OSF) { + printf ("### Warning: RTC oscillator has stopped\n"); + /* clear the OSF flag */ + rtc_write (RTC_STAT_REG_ADDR, + rtc_read (RTC_STAT_REG_ADDR) & ~RTC_STAT_BIT_OSF); + } + + tmp->tm_sec = bcd2bin (sec & 0x7F); + tmp->tm_min = bcd2bin (min & 0x7F); + tmp->tm_hour = bcd2bin (hour & 0x3F); + tmp->tm_mday = bcd2bin (mday & 0x3F); + tmp->tm_mon = bcd2bin (mon_cent & 0x1F); + tmp->tm_year = bcd2bin (year) + ((mon_cent & 0x80) ? 2000 : 1900); + tmp->tm_wday = bcd2bin ((wday - 1) & 0x07); + tmp->tm_yday = 0; + tmp->tm_isdst= 0; + + DEBUGR ("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); +} + + +/* + * Set the RTC + */ +void rtc_set (struct rtc_time *tmp) +{ + uchar century; + + DEBUGR ("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); + + rtc_write (RTC_YR_REG_ADDR, bin2bcd (tmp->tm_year % 100)); + + century = (tmp->tm_year >= 2000) ? 0x80 : 0; + rtc_write (RTC_MON_REG_ADDR, bin2bcd (tmp->tm_mon) | century); + + rtc_write (RTC_DAY_REG_ADDR, bin2bcd (tmp->tm_wday + 1)); + rtc_write (RTC_DATE_REG_ADDR, bin2bcd (tmp->tm_mday)); + rtc_write (RTC_HR_REG_ADDR, bin2bcd (tmp->tm_hour)); + rtc_write (RTC_MIN_REG_ADDR, bin2bcd (tmp->tm_min)); + rtc_write (RTC_SEC_REG_ADDR, bin2bcd (tmp->tm_sec)); +} + + +/* + * Reset the RTC. We also enable the oscillator output on the + * SQW/INTB* pin and program it for 32,768 Hz output. Note that + * according to the datasheet, turning on the square wave output + * increases the current drain on the backup battery from about + * 600 nA to 2uA. + */ +void rtc_reset (void) +{ + rtc_write (RTC_CTL_REG_ADDR, RTC_CTL_BIT_RS1 | RTC_CTL_BIT_RS2); +} + + +/* + * Helper functions + */ + +static +uchar rtc_read (uchar reg) +{ + return (i2c_reg_read (CFG_I2C_RTC_ADDR, reg)); +} + + +static void rtc_write (uchar reg, uchar val) +{ + i2c_reg_write (CFG_I2C_RTC_ADDR, reg, val); +} + +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)); +} + +#endif /* (CONFIG_RTC_DS3231) && (CONFIG_COMMANDS & CFG_CMD_DATE) */ |