drivers/rtc/ds164x.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * (C) Copyright 2002
 * ARIO Data Networks, Inc. dchiu@ariodata.com
 *
 * modified for DS164x:
 * The LEOX team <team@leox.org>, http://www.leox.org
 *
 * Based on MontaVista DS1743 code and U-Boot mc146818 code
 */

/*
 * Date & Time support for the DS164x RTC
 */

/* #define	RTC_DEBUG */

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


static uchar    rtc_read(unsigned int addr );
static void     rtc_write(unsigned int addr, uchar val);

#define RTC_EPOCH                 2000	/* century */

/*
 * DS164x registers layout
 */
#define RTC_BASE		( CONFIG_SYS_NVRAM_BASE_ADDR + CONFIG_SYS_NVRAM_SIZE )

#define RTC_YEAR		( RTC_BASE + 0x07 )
#define RTC_MONTH		( RTC_BASE + 0x06 )
#define RTC_DAY_OF_MONTH	( RTC_BASE + 0x05 )
#define RTC_DAY_OF_WEEK		( RTC_BASE + 0x04 )
#define RTC_HOURS		( RTC_BASE + 0x03 )
#define RTC_MINUTES		( RTC_BASE + 0x02 )
#define RTC_SECONDS		( RTC_BASE + 0x01 )
#define RTC_CONTROL		( RTC_BASE + 0x00 )

#define RTC_CONTROLA		RTC_CONTROL	/* W=bit6, R=bit5 */
#define   RTC_CA_WRITE		  0x80
#define   RTC_CA_READ		  0x40
#define RTC_CONTROLB		RTC_SECONDS	/* OSC=bit7       */
#define   RTC_CB_OSC_DISABLE	  0x80
#define RTC_CONTROLC		RTC_DAY_OF_WEEK	/* FT=bit6        */
#define   RTC_CC_FREQ_TEST	  0x40

/* ------------------------------------------------------------------------- */

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

	uchar reg_a;

	reg_a = rtc_read( RTC_CONTROLA );
	/* lock clock registers for read */
	rtc_write( RTC_CONTROLA, ( reg_a | RTC_CA_READ ));

	sec     = rtc_read( RTC_SECONDS );
	min     = rtc_read( RTC_MINUTES );
	hour    = rtc_read( RTC_HOURS );
	mday    = rtc_read( RTC_DAY_OF_MONTH );
	wday    = rtc_read( RTC_DAY_OF_WEEK );
	mon     = rtc_read( RTC_MONTH );
	year    = rtc_read( RTC_YEAR );

	/* unlock clock registers after read */
	rtc_write( RTC_CONTROLA, ( reg_a & ~RTC_CA_READ ));

#ifdef RTC_DEBUG
	printf( "Get RTC year: %02x mon: %02x mday: %02x wday: %02x "
		"hr: %02x min: %02x sec: %02x\n",
		year, mon, mday, wday,
		hour, min, sec );
#endif
	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_wday = bcd2bin( wday & 0x07 );

	/* glue year in century (2000) */
	tmp->tm_year = bcd2bin( year ) + RTC_EPOCH;

	tmp->tm_yday = 0;
	tmp->tm_isdst= 0;
#ifdef RTC_DEBUG
	printf( "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 );
#endif

	return 0;
}

int rtc_set( struct rtc_time *tmp )
{
	uchar reg_a;

#ifdef RTC_DEBUG
	printf( "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);
#endif
	/* lock clock registers for write */
	reg_a = rtc_read( RTC_CONTROLA );
	rtc_write( RTC_CONTROLA, ( reg_a | RTC_CA_WRITE ));

	rtc_write( RTC_MONTH, bin2bcd( tmp->tm_mon ));

	rtc_write( RTC_DAY_OF_WEEK, bin2bcd( tmp->tm_wday ));
	rtc_write( RTC_DAY_OF_MONTH, bin2bcd( tmp->tm_mday ));
	rtc_write( RTC_HOURS, bin2bcd( tmp->tm_hour ));
	rtc_write( RTC_MINUTES, bin2bcd( tmp->tm_min ));
	rtc_write( RTC_SECONDS, bin2bcd( tmp->tm_sec ));

	/* break year in century */
	rtc_write( RTC_YEAR, bin2bcd( tmp->tm_year % 100 ));

	/* unlock clock registers after read */
	rtc_write( RTC_CONTROLA, ( reg_a  & ~RTC_CA_WRITE ));

	return 0;
}

void rtc_reset (void)
{
	uchar reg_a, reg_b;

	reg_a = rtc_read( RTC_CONTROLA );
	reg_b = rtc_read( RTC_CONTROLB );

	if ( reg_b & RTC_CB_OSC_DISABLE )
	{
		printf( "real-time-clock was stopped. Now starting...\n" );
		reg_a |= RTC_CA_WRITE;
		reg_b &= ~RTC_CB_OSC_DISABLE;

		rtc_write( RTC_CONTROLA, reg_a );
		rtc_write( RTC_CONTROLB, reg_b );
	}

	/* make sure read/write clock register bits are cleared */
	reg_a &= ~( RTC_CA_WRITE | RTC_CA_READ );
	rtc_write( RTC_CONTROLA, reg_a );
}

/* ------------------------------------------------------------------------- */

static uchar rtc_read( unsigned int addr )
{
	uchar val = *(volatile unsigned char*)(addr);

#ifdef RTC_DEBUG
	printf( "rtc_read: %x:%x\n", addr, val );
#endif
	return( val );
}

static void rtc_write( unsigned int addr, uchar val )
{
#ifdef RTC_DEBUG
	printf( "rtc_write: %x:%x\n", addr, val );
#endif
	*(volatile unsigned char*)(addr) = val;
}