[U-Boot-Users] [PATCH] Add support for M41T60 serial access real-time clock
Lawrence R. Johnson
lrj at arlinx.com
Mon Jun 18 17:49:05 CEST 2007
Hi everyone,
Here is a patch to add support to U-Boot for the STMicroelectronics M41T60 serial RTC. I used the driver for the M41T11 as a template.
The code was tested using an AMCC Sequoia board (PPC440EPx processor) with the M41T60 connected to the board's I2C0 header.
In the intended application, the RTC will be powered by a large capacitor, rather than a battery. The driver therefore checks to see whether the RTC has lost power. The chip's OUT bit is normally reset from its power-up state. If the OUT bit is read as set, or if the date and time are not valid, then the RTC is assumed to have lost power, and its date and time are reset to 1900-01-01 00:00:00.
Signed-off-by: Larry Johnson <lrj at acm.org>
diff -Naur a/rtc/m41t60.c b/rtc/m41t60.c
--- a/rtc/m41t60.c 1969-12-31 19:00:00.000000000 -0500
+++ b/rtc/m41t60.c 2007-06-18 11:02:11.000000000 -0400
@@ -0,0 +1,234 @@
+/*
+ * (C) Copyright 2007
+ * Larry Johnson, lrj at acm.org
+ *
+ * based on rtc/m41t11.c which is ...
+ *
+ * (C) Copyright 2002
+ * Andrew May, Viasat Inc, amay at viasat.com
+ *
+ * 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
+ */
+
+/*
+ * STMicroelectronics M41T60 serial access real-time clock
+ */
+
+/* #define DEBUG 1 */
+
+#include <common.h>
+#include <command.h>
+#include <rtc.h>
+#include <i2c.h>
+
+#if defined(CONFIG_RTC_M41T60) && defined(CFG_I2C_RTC_ADDR) && \
+ (CONFIG_COMMANDS & CFG_CMD_DATE)
+
+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));
+}
+
+/*
+ Convert between century and "century bits" (CB1 and CB0). These
+ routines assume years are in the range 1900 - 2299.
+*/
+
+static unsigned char year2cb(unsigned const year)
+{
+ if (year < 1900 || year >= 2300) {
+ printf("M41T60 RTC: year %d out of range\n", year);
+ }
+ return (year / 100) & 0x3;
+}
+
+static unsigned cb2year(unsigned const cb)
+{
+ return 1900 + 100 * ((cb + 1) & 0x3);
+}
+
+/*
+ * These are simple defines for the chip local to here so they aren't too
+ * verbose. DAY/DATE aren't nice but that is how they are on the data sheet.
+ */
+#define RTC_SEC 0x0
+#define RTC_MIN 0x1
+#define RTC_HOUR 0x2
+#define RTC_DAY 0x3
+#define RTC_DATE 0x4
+#define RTC_MONTH 0x5
+#define RTC_YEARS 0x6
+
+#define RTC_REG_CNT 7
+
+#define RTC_CTRL 0x7
+
+#if defined(DEBUG)
+static void rtc_dump(char const *const label)
+{
+ uchar data[8];
+
+ if (i2c_read(CFG_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
+ printf("I2C read failed in rtc_dump()\n");
+ return;
+ }
+ printf("RTC dump %s: %02X-%02X-%02X-%02X-%02X-%02X-%02X-%02X\n",
+ label, data[0], data[1], data[2], data[3],
+ data[4], data[5], data[6], data[7]);
+}
+#else /* !defined(DEBUG) */
+#define rtc_dump(label)
+#endif /* defined(DEBUG) */
+
+static uchar *rtc_validate(void)
+{
+ static const uchar daysInMonth[0x13] = {
+ 0x00, 0x31, 0x29, 0x31, 0x30, 0x31, 0x30, 0x31,
+ 0x31, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ 0x31, 0x30, 0x31
+ };
+ static uchar data[8];
+ uchar min, date, month, years;
+
+ rtc_dump("begin validate");
+ if (i2c_read(CFG_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
+ printf("I2C read failed in rtc_validate()\n");
+ return 0;
+ }
+ /*
+ * If the OUT bit is "1", there has been a loss of power, then stop the
+ * oscillator is it will be "kick-started".
+ */
+ if (0x00 != (data[RTC_CTRL] & 0x80)) {
+ printf("M41T60 RTC clock lost power.\n");
+ data[RTC_SEC] = 0x80;
+ if (i2c_write(CFG_I2C_RTC_ADDR, RTC_SEC, 1, data, 1)) {
+ printf("I2C write failed in rtc_validate()\n");
+ return 0;
+ }
+ }
+ /*
+ * If the ocsillator is stopped or the date is invalid, then set the OUT
+ * bit to "1", reset the date registers, and start the oscillator.
+ */
+ min = data[RTC_MIN] & 0x7F;
+ date = data[RTC_DATE];
+ month = data[RTC_MONTH] & 0x3F;
+ years = data[RTC_YEARS];
+ if (0x59 < data[RTC_SEC] || 0x09 < (data[RTC_SEC] & 0x0F) ||
+ 0x59 < min || 0x09 < (min & 0x0F) ||
+ 0x23 < data[RTC_HOUR] || 0x09 < (data[RTC_HOUR] & 0x0F) ||
+ 0x07 < data[RTC_DAY] || 0x00 == data[RTC_DAY] ||
+ 0x12 < month ||
+ 0x99 < years || 0x09 < (years & 0x0F) ||
+ daysInMonth[month] < date || 0x09 < (date & 0x0F) || 0x00 == date ||
+ (0x29 == date && 0x02 == month &&
+ ((0x00 != (years & 0x03)) ||
+ (0x00 == years && 0x00 != (data[RTC_MONTH] & 0xC0))))) {
+ printf("Resetting M41T60 RTC clock.\n");
+ /*
+ * Set to 00:00:00 1900-01-01 (Monday)
+ */
+ data[RTC_SEC] = 0x00;
+ data[RTC_MIN] = 0x00;
+ data[RTC_HOUR] = 0x00;
+ data[RTC_DAY] = 0x02;
+ data[RTC_DATE] = 0x01;
+ data[RTC_MONTH] = 0xC1;
+ data[RTC_YEARS] = 0x00;
+ data[RTC_CTRL] &= 0x7F;
+ }
+ if (i2c_write(CFG_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
+ printf("I2C write failed in rtc_validate()\n");
+ return 0;
+ }
+ return data;
+}
+
+void rtc_get(struct rtc_time *tmp)
+{
+ uchar const *const data = rtc_validate();
+
+ if (!data) {
+ return;
+ }
+ tmp->tm_sec = bcd2bin(data[RTC_SEC] & 0x7F);
+ tmp->tm_min = bcd2bin(data[RTC_MIN] & 0x7F);
+ tmp->tm_hour = bcd2bin(data[RTC_HOUR] & 0x3F);
+ tmp->tm_mday = bcd2bin(data[RTC_DATE] & 0x3F);
+ tmp->tm_mon = bcd2bin(data[RTC_MONTH] & 0x1F);
+ tmp->tm_year = cb2year(data[RTC_MONTH] >> 6) + bcd2bin(data[RTC_YEARS]);
+ tmp->tm_wday = bcd2bin(data[RTC_DAY] & 0x07) - 1;
+ 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);
+}
+
+void rtc_set(struct rtc_time *tmp)
+{
+ uchar *const data = rtc_validate();
+
+ if (!data) {
+ return;
+ }
+ data[RTC_SEC] &= 0x80;
+ data[RTC_MIN] &= 0X80;
+
+ 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);
+
+ data[RTC_SEC] |= bin2bcd(tmp->tm_sec) & 0x7F;
+ data[RTC_MIN] |= bin2bcd(tmp->tm_min) & 0X7F;
+ data[RTC_HOUR] = bin2bcd(tmp->tm_hour) & 0x3F;
+ data[RTC_DATE] = bin2bcd(tmp->tm_mday) & 0x3F;
+ data[RTC_MONTH] = bin2bcd(tmp->tm_mon) & 0x1F;
+ data[RTC_YEARS] = bin2bcd(tmp->tm_year % 100);
+ data[RTC_MONTH] |= year2cb(tmp->tm_year) << 6;
+ data[RTC_DAY] = bin2bcd(tmp->tm_wday + 1) & 0x07;
+ if (i2c_write(CFG_I2C_RTC_ADDR, 0, 1, data, RTC_REG_CNT)) {
+ printf("I2C write failed in rtc_set()\n");
+ return;
+ }
+}
+
+void rtc_reset(void)
+{
+ uchar *const data = rtc_validate();
+
+ if (!data) {
+ return;
+ }
+ rtc_dump("begin reset");
+ /*
+ * Turn off frequency test.
+ */
+ data[RTC_CTRL] &= 0xBF;
+ if (i2c_write(CFG_I2C_RTC_ADDR, RTC_CTRL, 1, data + RTC_CTRL, 1)) {
+ printf("I2C write failed in rtc_reset()\n");
+ return;
+ }
+ rtc_dump("end reset");
+}
+#endif /* CONFIG_RTC_M41T60 && CFG_I2C_RTC_ADDR && CFG_CMD_DATE */
diff -Naur a/rtc/Makefile b/rtc/Makefile
--- a/rtc/Makefile 2007-06-12 08:23:00.000000000 -0400
+++ b/rtc/Makefile 2007-06-16 11:46:11.000000000 -0400
@@ -31,7 +31,8 @@
bf5xx_rtc.o ds12887.o ds1302.o ds1306.o ds1307.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
+ mpc5xxx.o mpc8xx.o pcf8563.o s3c24x0_rtc.o rs5c372.o \
+ m41t60.o
SRCS := $(COBJS:.o=.c)
OBJS := $(addprefix $(obj),$(COBJS))
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