rtc: add support for 4543 RTC (manufactured by e.g. EPSON)

Signed-off-by: Detlev Zundel <dzu@denx.de>
Signed-off-by: Andreas Pfefferle <ap@denx.de>

drivers/rtc/Makefile

@@ -55,6 +55,7 @@ COBJS-$(CONFIG_RTC_MPC8xx) += mpc8xx.o
 COBJS-$(CONFIG_RTC_PCF8563) += pcf8563.o
 COBJS-$(CONFIG_RTC_PL031) += pl031.o
 COBJS-$(CONFIG_RTC_RS5C372A) += rs5c372.o
+COBJS-$(CONFIG_RTC_RTC4543) += rtc4543.o
 COBJS-$(CONFIG_RTC_RX8025) += rx8025.o
 COBJS-$(CONFIG_RTC_S3C24X0) += s3c24x0_rtc.o
 COBJS-$(CONFIG_RTC_X1205) += x1205.o

drivers/rtc/rtc4543.c

+/*
+ * (C) Copyright 2008, 2009
+ * Andreas Pfefferle, DENX Software Engineering, ap@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
+ */
+
+#include <asm/io.h>
+#include <common.h>
+#include <command.h>
+#include <config.h>
+#include <bcd.h>
+#include <rtc.h>
+#include <tws.h>
+
+#if defined(CONFIG_CMD_DATE)
+
+/*
+ * Note: The acrobatics below is due to the hideously ingenius idea of
+ * the chip designers.  As the chip does not allow register
+ * addressing, all values need to be read and written in one go.  Sure
+ * enough, the 'wday' field (0-6) is transferred using the economic
+ * number of 4 bits right in the middle of the packet.....
+ */
+
+int rtc_get(struct rtc_time *tm)
+{
+	int rel = 0;
+	uchar buffer[7];
+
+	memset(buffer, 0, 7);
+
+	/* Read 52 bits into our buffer */
+	tws_read(buffer, 52);
+
+	tm->tm_sec  = BCD2BIN( buffer[0] & 0x7F);
+	tm->tm_min  = BCD2BIN( buffer[1] & 0x7F);
+	tm->tm_hour = BCD2BIN( buffer[2] & 0x3F);
+	tm->tm_wday = BCD2BIN( buffer[3] & 0x07);
+	tm->tm_mday = BCD2BIN((buffer[3] & 0xF0) >> 4 | (buffer[4] & 0x0F) << 4);
+	tm->tm_mon  = BCD2BIN((buffer[4] & 0x30) >> 4 | (buffer[5] & 0x0F) << 4);
+	tm->tm_year = BCD2BIN((buffer[5] & 0xF0) >> 4 | (buffer[6] & 0x0F) << 4) + 2000;
+	tm->tm_yday = 0;
+	tm->tm_isdst = 0;
+
+	if (tm->tm_sec & 0x80) {
+		puts("### Warning: RTC Low Voltage - date/time not reliable\n");
+		rel = -1;
+	}
+
+	debug("Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
+		tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_wday,
+		tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+	return rel;
+}
+
+int rtc_set(struct rtc_time *tm)
+{
+	uchar buffer[7];
+	uchar tmp;
+
+	debug("Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
+		tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_wday,
+		tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+	memset(buffer, 0, 7);
+	buffer[0] = BIN2BCD(tm->tm_sec);
+	buffer[1] = BIN2BCD(tm->tm_min);
+	buffer[2] = BIN2BCD(tm->tm_hour);
+	buffer[3] = BIN2BCD(tm->tm_wday);
+	tmp = BIN2BCD(tm->tm_mday);
+	buffer[3] |= (tmp & 0x0F) << 4;
+	buffer[4] =  (tmp & 0xF0) >> 4;
+	tmp = BIN2BCD(tm->tm_mon);
+	buffer[4] |= (tmp & 0x0F) << 4;
+	buffer[5] =  (tmp & 0xF0) >> 4;
+	tmp = BIN2BCD(tm->tm_year  % 100);
+	buffer[5] |= (tmp & 0x0F) << 4;
+	buffer[6] =  (tmp & 0xF0) >> 4;
+
+	/* Write the resulting 52 bits to device */
+	tws_write(buffer, 52);
+
+	return 0;
+}
+
+void rtc_reset(void)
+{
+	struct rtc_time tmp;
+
+	tmp.tm_sec = 0;
+	tmp.tm_min = 0;
+	tmp.tm_hour = 0;
+	tmp.tm_wday = 4;
+	tmp.tm_mday = 1;
+	tmp.tm_mon = 1;
+	tmp.tm_year = 2000;
+	rtc_set(&tmp);
+}
+
+#endif

include/rtc.h

@@ -61,4 +61,8 @@ void to_tm (int, struct rtc_time *);
 unsigned long mktime (unsigned int, unsigned int, unsigned int,
 		      unsigned int, unsigned int, unsigned int);
 
+uchar rtc_read(uchar reg) __attribute__((weak));
+void  rtc_write(uchar reg, uchar val) __attribute__((weak));
+
+
 #endif	/* _RTC_H_ */