Add driver for the ST M41T94 SPI RTC
This RTC is used in some Calao boards. The driver code is taken from
the linux rtc-m41t94 driver
Signed-off-by: Albin Tonnerre <albin.tonnerre@free-electrons.com>
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 822dc1a..ea7d899 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -44,6 +44,7 @@
COBJS-$(CONFIG_RTC_M41T11) += m41t11.o
COBJS-$(CONFIG_RTC_M41T60) += m41t60.o
COBJS-$(CONFIG_RTC_M41T62) += m41t62.o
+COBJS-$(CONFIG_RTC_M41T94) += m41t94.o
COBJS-$(CONFIG_RTC_M48T35A) += m48t35ax.o
COBJS-$(CONFIG_RTC_MAX6900) += max6900.o
COBJS-$(CONFIG_RTC_MC13783) += mc13783-rtc.o
diff --git a/drivers/rtc/m41t94.c b/drivers/rtc/m41t94.c
new file mode 100644
index 0000000..02b41d9
--- /dev/null
+++ b/drivers/rtc/m41t94.c
@@ -0,0 +1,124 @@
+/*
+ * Driver for ST M41T94 SPI RTC
+ *
+ * Taken from the Linux kernel drivier:
+ * Copyright (C) 2008 Kim B. Heino
+ *
+ * Adaptation for U-Boot:
+ * Copyright (C) 2009
+ * Albin Tonnerre, Free Electrons <albin.tonnerre@free-electrons.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <common.h>
+#include <rtc.h>
+#include <spi.h>
+
+static struct spi_slave *slave;
+
+#define M41T94_REG_SECONDS 0x01
+#define M41T94_REG_MINUTES 0x02
+#define M41T94_REG_HOURS 0x03
+#define M41T94_REG_WDAY 0x04
+#define M41T94_REG_DAY 0x05
+#define M41T94_REG_MONTH 0x06
+#define M41T94_REG_YEAR 0x07
+#define M41T94_REG_HT 0x0c
+
+#define M41T94_BIT_HALT 0x40
+#define M41T94_BIT_STOP 0x80
+#define M41T94_BIT_CB 0x40
+#define M41T94_BIT_CEB 0x80
+
+int rtc_set(struct rtc_time *tm)
+{
+ u8 buf[8]; /* write cmd + 7 registers */
+ int ret;
+
+ if (!slave) {
+ slave = spi_setup_slave(CONFIG_M41T94_SPI_BUS,
+ CONFIG_M41T94_SPI_CS, 1000000,
+ SPI_MODE_3);
+ if (!slave)
+ return -1;
+ }
+ spi_claim_bus(slave);
+
+ buf[0] = 0x80 | M41T94_REG_SECONDS; /* write time + date */
+ buf[M41T94_REG_SECONDS] = bin2bcd(tm->tm_sec);
+ buf[M41T94_REG_MINUTES] = bin2bcd(tm->tm_min);
+ buf[M41T94_REG_HOURS] = bin2bcd(tm->tm_hour);
+ buf[M41T94_REG_WDAY] = bin2bcd(tm->tm_wday + 1);
+ buf[M41T94_REG_DAY] = bin2bcd(tm->tm_mday);
+ buf[M41T94_REG_MONTH] = bin2bcd(tm->tm_mon + 1);
+
+ buf[M41T94_REG_HOURS] |= M41T94_BIT_CEB;
+ if (tm->tm_year >= 100)
+ buf[M41T94_REG_HOURS] |= M41T94_BIT_CB;
+ buf[M41T94_REG_YEAR] = bin2bcd(tm->tm_year % 100);
+
+ ret = spi_xfer(slave, 64, buf, NULL, SPI_XFER_BEGIN | SPI_XFER_END);
+ spi_release_bus(slave);
+ return ret;
+}
+
+int rtc_get(struct rtc_time *tm)
+{
+ u8 buf[2];
+ int ret, hour;
+
+ if (!slave) {
+ slave = spi_setup_slave(CONFIG_M41T94_SPI_BUS,
+ CONFIG_M41T94_SPI_CS, 1000000,
+ SPI_MODE_3);
+ if (!slave)
+ return -1;
+ }
+ spi_claim_bus(slave);
+
+ /* clear halt update bit */
+ ret = spi_w8r8(slave, M41T94_REG_HT);
+ if (ret < 0)
+ return ret;
+ if (ret & M41T94_BIT_HALT) {
+ buf[0] = 0x80 | M41T94_REG_HT;
+ buf[1] = ret & ~M41T94_BIT_HALT;
+ spi_xfer(slave, 16, buf, NULL, SPI_XFER_BEGIN | SPI_XFER_END);
+ }
+
+ /* clear stop bit */
+ ret = spi_w8r8(slave, M41T94_REG_SECONDS);
+ if (ret < 0)
+ return ret;
+ if (ret & M41T94_BIT_STOP) {
+ buf[0] = 0x80 | M41T94_REG_SECONDS;
+ buf[1] = ret & ~M41T94_BIT_STOP;
+ spi_xfer(slave, 16, buf, NULL, SPI_XFER_BEGIN | SPI_XFER_END);
+ }
+
+ tm->tm_sec = bcd2bin(spi_w8r8(slave, M41T94_REG_SECONDS));
+ tm->tm_min = bcd2bin(spi_w8r8(slave, M41T94_REG_MINUTES));
+ hour = spi_w8r8(slave, M41T94_REG_HOURS);
+ tm->tm_hour = bcd2bin(hour & 0x3f);
+ tm->tm_wday = bcd2bin(spi_w8r8(slave, M41T94_REG_WDAY)) - 1;
+ tm->tm_mday = bcd2bin(spi_w8r8(slave, M41T94_REG_DAY));
+ tm->tm_mon = bcd2bin(spi_w8r8(slave, M41T94_REG_MONTH)) - 1;
+ tm->tm_year = bcd2bin(spi_w8r8(slave, M41T94_REG_YEAR));
+ if ((hour & M41T94_BIT_CB) || !(hour & M41T94_BIT_CEB))
+ tm->tm_year += 100;
+
+ spi_release_bus(slave);
+ return 0;
+}
+
+void rtc_reset(void)
+{
+ /*
+ * Could not be tested as the reset pin is not wired on
+ * the sbc35-ag20 board
+ */
+ return 0;
+}