drivers/rtc/isl1208.c

/*
 * (C) Copyright 2008
 * Tor Krill, Excito Elektronik i Skåne , tor@excito.com
 *
 * Modelled after the ds1337 driver
 *
 * 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 Intersil
 * ISL1208 Real Time Clock (RTC).
 */

#include <common.h>
#include <command.h>
#include <rtc.h>
#include <i2c.h>

/*---------------------------------------------------------------------*/
#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_DATE_REG_ADDR	0x3
#define RTC_MON_REG_ADDR	0x4
#define RTC_YR_REG_ADDR		0x5
#define RTC_DAY_REG_ADDR	0x6
#define RTC_STAT_REG_ADDR	0x7
/*
 * RTC control register bits
 */

/*
 * RTC status register bits
 */
#define RTC_STAT_BIT_ARST	0x80	/* AUTO RESET ENABLE BIT */
#define RTC_STAT_BIT_XTOSCB	0x40	/* CRYSTAL OSCILLATOR ENABLE BIT */
#define RTC_STAT_BIT_WRTC	0x10	/* WRITE RTC ENABLE BIT */
#define RTC_STAT_BIT_ALM	0x04	/* ALARM BIT */
#define RTC_STAT_BIT_BAT	0x02	/* BATTERY BIT */
#define RTC_STAT_BIT_RTCF	0x01	/* REAL TIME CLOCK FAIL BIT */

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
 */

int rtc_get (struct rtc_time *tmp)
{
	int rel = 0;
	uchar sec, min, hour, mday, wday, mon, year, status;

	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 = rtc_read (RTC_MON_REG_ADDR);
	year = rtc_read (RTC_YR_REG_ADDR);

	DEBUGR ("Get RTC year: %02x mon: %02x mday: %02x wday: %02x "
		"hr: %02x min: %02x sec: %02x status: %02x\n",
		year, mon, mday, wday, hour, min, sec, status);

	if (status & RTC_STAT_BIT_RTCF) {
		printf ("### Warning: RTC oscillator has stopped\n");
		rtc_write(RTC_STAT_REG_ADDR,
			rtc_read(RTC_STAT_REG_ADDR) &~ (RTC_STAT_BIT_BAT|RTC_STAT_BIT_RTCF));
		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 & 0x1F);
	tmp->tm_year = bcd2bin (year)+2000;
	tmp->tm_wday = bcd2bin (wday & 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);

	return rel;
}

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

	/* enable write */
	rtc_write(RTC_STAT_REG_ADDR,
		rtc_read(RTC_STAT_REG_ADDR) | RTC_STAT_BIT_WRTC);

	rtc_write (RTC_YR_REG_ADDR, bin2bcd (tmp->tm_year % 100));
	rtc_write (RTC_MON_REG_ADDR, bin2bcd (tmp->tm_mon));
	rtc_write (RTC_DAY_REG_ADDR, bin2bcd (tmp->tm_wday));
	rtc_write (RTC_DATE_REG_ADDR, bin2bcd (tmp->tm_mday));
	rtc_write (RTC_HR_REG_ADDR, bin2bcd (tmp->tm_hour) | 0x80 ); /* 24h clock */
	rtc_write (RTC_MIN_REG_ADDR, bin2bcd (tmp->tm_min));
	rtc_write (RTC_SEC_REG_ADDR, bin2bcd (tmp->tm_sec));

	/* disable write */
	rtc_write(RTC_STAT_REG_ADDR,
		rtc_read(RTC_STAT_REG_ADDR) & ~RTC_STAT_BIT_WRTC);

	return 0;
}

void rtc_reset (void)
{
}

/*
 * 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));
}