Add support for the DS3231 RTC

2 files changed, 194 insertions, 1 deletions

diff --git a/rtc/Makefile b/rtc/Makefile
index cf2b24ef0dd..cdc8ac934f9 100644
--- a/rtc/Makefile
+++ b/rtc/Makefile
@@ -29,7 +29,7 @@ LIB	= $(obj)librtc.a
 
 COBJS	= date.o   \
 	  bf533_rtc.o ds12887.o ds1302.o ds1306.o ds1307.o \
-	  ds1337.o ds1374.o ds1556.o ds164x.o ds174x.o \
+	  ds1337.o ds1374.o ds1556.o ds164x.o ds174x.o ds3231.o \
 	  m41t11.o max6900.o m48t35ax.o mc146818.o mk48t59.o \
 	  mpc5xxx.o mpc8xx.o pcf8563.o s3c24x0_rtc.o rs5c372.o
 
diff --git a/rtc/ds3231.c b/rtc/ds3231.c
new file mode 100644
index 00000000000..50aeeb5615d
--- /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) */