rtc: add support for s35392a

Add support for S35392A RTC. The driver supports both U-Boot driver
models.

Signed-off-by: Nandor Han <nandor.han@ge.com>
Signed-off-by: Martyn Welch <martyn.welch@collabora.co.uk>
Cc: Heiko Schocher <hs@denx.de>

3 files changed, 372 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index d06130c7a2..2964bb2211 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -30,4 +30,10 @@ config RTC_DS1307
 	  Support for Dallas Semiconductor (now Maxim) DS1307 and DS1338/9 and
 	  compatible Real Time Clock devices.
 
+config RTC_S35392A
+	bool "Enable S35392A driver"
+	select BITREVERSE
+	help
+	  Enable s35392a driver which provides rtc get and set function.
+
 endmenu
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 003e31aeba..7a8f97a05f 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -49,5 +49,6 @@ obj-$(CONFIG_RTC_RS5C372A) += rs5c372.o
 obj-$(CONFIG_RTC_RV3029) += rv3029.o
 obj-$(CONFIG_RTC_RX8025) += rx8025.o
 obj-$(CONFIG_RTC_S3C24X0) += s3c24x0_rtc.o
+obj-$(CONFIG_RTC_S35392A) += s35392a.o
 obj-$(CONFIG_SANDBOX) += sandbox_rtc.o
 obj-$(CONFIG_RTC_X1205) += x1205.o
diff --git a/drivers/rtc/s35392a.c b/drivers/rtc/s35392a.c
new file mode 100644
index 0000000000..9adcefc98d
--- /dev/null
+++ b/drivers/rtc/s35392a.c
@@ -0,0 +1,365 @@
+/*
+ * SII Semiconductor Corporation S35392A RTC driver.
+ *
+ * Copyright (c) 2017, General Electric Company
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ */
+
+#include <command.h>
+#include <common.h>
+#include <dm.h>
+#include <i2c.h>
+#include <linux/bitrev.h>
+#include <rtc.h>
+
+#define S35390A_CMD_STATUS1		0x30
+#define S35390A_CMD_STATUS2		0x31
+#define S35390A_CMD_TIME1		0x32
+#define S35390A_CMD_TIME2		0x33
+#define S35390A_CMD_INT2_REG1	0x35
+
+#define S35390A_BYTE_YEAR	0
+#define S35390A_BYTE_MONTH	1
+#define S35390A_BYTE_DAY	2
+#define S35390A_BYTE_WDAY	3
+#define S35390A_BYTE_HOURS	4
+#define S35390A_BYTE_MINS	5
+#define S35390A_BYTE_SECS	6
+
+/* flags for STATUS1 */
+#define S35390A_FLAG_POC	0x01
+#define S35390A_FLAG_BLD	0x02
+#define S35390A_FLAG_INT2	0x04
+#define S35390A_FLAG_24H	0x40
+#define S35390A_FLAG_RESET	0x80
+
+/*
+ * If either BLD or POC is set, then the chip has lost power long enough for
+ * the time value to become invalid.
+ */
+#define S35390A_LOW_VOLTAGE (S35390A_FLAG_POC | S35390A_FLAG_BLD)
+
+/*---------------------------------------------------------------------*/
+#undef DEBUG_RTC
+
+#ifdef DEBUG_RTC
+#define DEBUGR(fmt, args...) printf(fmt, ##args)
+#else
+#define DEBUGR(fmt, args...)
+#endif
+/*---------------------------------------------------------------------*/
+
+#ifdef CONFIG_DM_RTC
+#define DEV_TYPE struct udevice
+#else
+/* Local udevice */
+struct ludevice {
+	u8 chip;
+};
+
+#define DEV_TYPE struct ludevice
+struct ludevice dev;
+
+#endif
+
+#define msleep(a) udelay(a * 1000)
+
+int lowvoltage;
+
+static int s35392a_rtc_reset(DEV_TYPE *dev);
+
+static int s35392a_rtc_read(DEV_TYPE *dev, u8 reg, u8 *buf, int len)
+{
+	int ret;
+
+#ifdef CONFIG_DM_RTC
+	/* TODO: we need to tweak the chip address to reg */
+	ret = dm_i2c_read(dev, 0, buf, len);
+#else
+	(void)dev;
+	ret = i2c_read(reg, 0, -1, buf, len);
+#endif
+
+	return ret;
+}
+
+static int s35392a_rtc_write(DEV_TYPE *dev, u8 reg, u8 *buf, int len)
+{
+	int ret;
+
+#ifdef CONFIG_DM_RTC
+	/* TODO: we need to tweak the chip address to reg */
+	ret = dm_i2c_write(dev, 0, buf, 1);
+#else
+	(void)dev;
+	ret = i2c_write(reg, 0, 0, buf, len);
+#endif
+
+	return ret;
+}
+
+static int s35392a_rtc_read8(DEV_TYPE *dev, unsigned int reg)
+{
+	u8 val;
+	int ret;
+
+	ret = s35392a_rtc_read(dev, reg, &val, sizeof(val));
+	return ret < 0 ? ret : val;
+}
+
+static int s35392a_rtc_write8(DEV_TYPE *dev, unsigned int reg, int val)
+{
+	int ret;
+	u8 lval = val;
+
+	ret = s35392a_rtc_write(dev, reg, &lval, sizeof(lval));
+	return ret < 0 ? ret : 0;
+}
+
+static int validate_time(const struct rtc_time *tm)
+{
+	if ((tm->tm_year < 2000) || (tm->tm_year > 2099))
+		return -EINVAL;
+
+	if ((tm->tm_mon < 1) || (tm->tm_mon > 12))
+		return -EINVAL;
+
+	if ((tm->tm_mday < 1) || (tm->tm_mday > 31))
+		return -EINVAL;
+
+	if ((tm->tm_wday < 0) || (tm->tm_wday > 6))
+		return -EINVAL;
+
+	if ((tm->tm_hour < 0) || (tm->tm_hour > 23))
+		return -EINVAL;
+
+	if ((tm->tm_min < 0) || (tm->tm_min > 59))
+		return -EINVAL;
+
+	if ((tm->tm_sec < 0) || (tm->tm_sec > 59))
+		return -EINVAL;
+
+	return 0;
+}
+
+void s35392a_rtc_init(DEV_TYPE *dev)
+{
+	int status;
+
+	status = s35392a_rtc_read8(dev, S35390A_CMD_STATUS1);
+	if (status < 0)
+		goto error;
+
+	DEBUGR("init: S35390A_CMD_STATUS1: 0x%x\n", status);
+
+	lowvoltage = status & S35390A_LOW_VOLTAGE ? 1 : 0;
+
+	if (status & S35390A_FLAG_POC)
+		/*
+		 * Do not communicate for 0.5 seconds since the power-on
+		 * detection circuit is in operation.
+		 */
+		msleep(500);
+
+	else if (!lowvoltage)
+		/*
+		 * If both POC and BLD are unset everything is fine.
+		 */
+		return;
+
+	if (lowvoltage)
+		printf("RTC low voltage detected\n");
+
+	if (!s35392a_rtc_reset(dev))
+		return;
+
+error:
+	printf("Error RTC init.\n");
+}
+
+/* Get the current time from the RTC */
+static int s35392a_rtc_get(DEV_TYPE *dev, struct rtc_time *tm)
+{
+	u8 date[7];
+	int ret, i;
+
+	if (lowvoltage) {
+		DEBUGR("RTC low voltage detected\n");
+		return -EINVAL;
+	}
+
+	ret = s35392a_rtc_read(dev, S35390A_CMD_TIME1, date, sizeof(date));
+	if (ret < 0) {
+		DEBUGR("Error reading date from RTC\n");
+		return -EIO;
+	}
+
+	/* This chip returns the bits of each byte in reverse order */
+	for (i = 0; i < 7; ++i)
+		date[i] = bitrev8(date[i]);
+
+	tm->tm_sec  = bcd2bin(date[S35390A_BYTE_SECS]);
+	tm->tm_min  = bcd2bin(date[S35390A_BYTE_MINS]);
+	tm->tm_hour = bcd2bin(date[S35390A_BYTE_HOURS] & ~S35390A_FLAG_24H);
+	tm->tm_wday = bcd2bin(date[S35390A_BYTE_WDAY]);
+	tm->tm_mday = bcd2bin(date[S35390A_BYTE_DAY]);
+	tm->tm_mon  = bcd2bin(date[S35390A_BYTE_MONTH]);
+	tm->tm_year = bcd2bin(date[S35390A_BYTE_YEAR]) + 2000;
+
+	DEBUGR("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 0;
+}
+
+/* Set the RTC */
+static int s35392a_rtc_set(DEV_TYPE *dev, const struct rtc_time *tm)
+{
+	int i, ret;
+	int status;
+	u8 date[7];
+
+	DEBUGR("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);
+
+	ret = validate_time(tm);
+	if (ret < 0)
+		return -EINVAL;
+
+	/* We support only 24h mode */
+	ret = s35392a_rtc_read8(dev, S35390A_CMD_STATUS1);
+	if (ret < 0)
+		return -EIO;
+	status = ret;
+
+	ret = s35392a_rtc_write8(dev, S35390A_CMD_STATUS1,
+				 status | S35390A_FLAG_24H);
+	if (ret < 0)
+		return -EIO;
+
+	date[S35390A_BYTE_YEAR]  = bin2bcd(tm->tm_year - 2000);
+	date[S35390A_BYTE_MONTH] = bin2bcd(tm->tm_mon);
+	date[S35390A_BYTE_DAY]   = bin2bcd(tm->tm_mday);
+	date[S35390A_BYTE_WDAY]  = bin2bcd(tm->tm_wday);
+	date[S35390A_BYTE_HOURS] = bin2bcd(tm->tm_hour);
+	date[S35390A_BYTE_MINS]  = bin2bcd(tm->tm_min);
+	date[S35390A_BYTE_SECS]  = bin2bcd(tm->tm_sec);
+
+	/* This chip expects the bits of each byte to be in reverse order */
+	for (i = 0; i < 7; ++i)
+		date[i] = bitrev8(date[i]);
+
+	ret = s35392a_rtc_write(dev, S35390A_CMD_TIME1, date, sizeof(date));
+	if (ret < 0) {
+		DEBUGR("Error writing date to RTC\n");
+		return -EIO;
+	}
+
+	/* Now we have time. Reset the low voltage status */
+	lowvoltage = 0;
+
+	return 0;
+}
+
+/* Reset the RTC. */
+static int s35392a_rtc_reset(DEV_TYPE *dev)
+{
+	int buf;
+	int ret;
+	unsigned int initcount = 0;
+
+	buf = S35390A_FLAG_RESET;
+
+initialize:
+	ret = s35392a_rtc_write8(dev, S35390A_CMD_STATUS1, buf);
+	if (ret < 0)
+		return -EIO;
+
+	ret = s35392a_rtc_read8(dev, S35390A_CMD_STATUS1);
+	if (ret < 0)
+		return -EIO;
+	buf = ret;
+
+	if (!lowvoltage)
+		lowvoltage = buf & S35390A_LOW_VOLTAGE ? 1 : 0;
+
+	if (buf & S35390A_LOW_VOLTAGE) {
+		/* Try up to five times to reset the chip */
+		if (initcount < 5) {
+			++initcount;
+			goto initialize;
+		} else {
+			return -EIO;
+		}
+	}
+
+	return 0;
+}
+
+#ifndef CONFIG_DM_RTC
+
+int rtc_get(struct rtc_time *tm)
+{
+	return s35392a_rtc_get(&dev, tm);
+}
+
+int rtc_set(struct rtc_time *tm)
+{
+	return s35392a_rtc_set(&dev, tm);
+}
+
+void rtc_reset(void)
+{
+	s35392a_rtc_reset(&dev);
+}
+
+void rtc_init(void)
+{
+	s35392a_rtc_init(&dev);
+}
+
+#else
+
+static int s35392a_probe(struct udevice *dev)
+{
+	s35392a_rtc_init(dev);
+	return 0;
+}
+
+static const struct rtc_ops s35392a_rtc_ops = {
+	.get = s35392a_rtc_get,
+	.set = s35392a_rtc_set,
+	.read8 = s35392a_rtc_read8,
+	.write8 = s35392a_rtc_write8,
+	.reset = s35392a_rtc_reset,
+};
+
+static const struct udevice_id s35392a_rtc_ids[] = {
+	{ .compatible = "sii,s35392a-rtc" },
+	{ }
+};
+
+U_BOOT_DRIVER(s35392a_rtc) = {
+	.name	  = "s35392a_rtc",
+	.id	      = UCLASS_RTC,
+	.probe    = s35392a_probe,
+	.of_match = s35392a_rtc_ids,
+	.ops	  = &s35392a_rtc_ops,
+};
+
+#endif