/*
 * (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_CMD_DATE)

/*
 * 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);


/*
 * Get the current time from the RTC
 */
int rtc_get (struct rtc_time *tmp)
{
        int rel = 0;
        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);

        debug("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);
                rel = -1;
        }

        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;

        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 rel;
}


/*
 * Set the RTC
 */
int rtc_set (struct rtc_time *tmp)
{
        uchar century;

        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);

        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));

        return 0;
}


/*
 * 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 (CONFIG_SYS_I2C_RTC_ADDR, reg));
}


static void rtc_write (uchar reg, uchar val)
{
        i2c_reg_write (CONFIG_SYS_I2C_RTC_ADDR, reg, val);
}

#endif