rtc: import ds1307 driver from linux-3.15

Current ds1307 rtc driver supports only ds1307 and ds1338 chips;
it has no nvram support at the moment.

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

3 files changed, 373 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 540150373d..c2b3764a3d 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -13,3 +13,25 @@ menuconfig RTC_CLASS
 	  Generic RTC class support. If you say yes here, you will
 	  be allowed to plug one or more RTCs to your system. You will
 	  probably want to enable one or more of the interfaces below.
+
+if RTC_CLASS
+
+comment "I2C RTC drivers"
+	depends on I2C
+
+if I2C
+
+config RTC_DRV_DS1307
+	tristate "Dallas/Maxim DS1307/38"
+	help
+	  If you say yes here you get support for various compatible RTC
+	  chips (often with battery backup) connected with I2C. This driver
+	  should handle DS1307, DS1338 and probably other chips.
+
+	  The first seven registers on these chips hold an RTC, and other
+	  registers may add features such as NVRAM, a trickle charger for
+	  the RTC/NVRAM backup power, and alarms.
+
+endif # I2C
+
+endif # RTC_CLASS
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 7d1b5bc8c8..2c5a50e864 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -4,3 +4,7 @@
 
 obj-$(CONFIG_RTC_LIB)           += rtc-lib.o
 obj-$(CONFIG_RTC_CLASS)         += class.o
+
+# Keep the list ordered.
+
+obj-$(CONFIG_RTC_DRV_DS1307)    += rtc-ds1307.o
diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
new file mode 100644
index 0000000000..725f15ab57
--- /dev/null
+++ b/drivers/rtc/rtc-ds1307.c
@@ -0,0 +1,347 @@
+/*
+ * rtc-ds1307.c - RTC driver for some mostly-compatible I2C chips.
+ *
+ *  This code was ported from linux-3.15 kernel by Antony Pavlov.
+ *
+ *  Copyright (C) 2005 James Chapman (ds1337 core)
+ *  Copyright (C) 2006 David Brownell
+ *  Copyright (C) 2009 Matthias Fuchs (rx8025 support)
+ *  Copyright (C) 2012 Bertrand Achard (nvram access fixes)
+ *
+ * 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 <init.h>
+#include <driver.h>
+#include <xfuncs.h>
+#include <errno.h>
+#include <i2c/i2c.h>
+#include <rtc.h>
+#include <linux/rtc.h>
+#include <linux/bcd.h>
+
+/*
+ * We can't determine type by probing, but if we expect pre-Linux code
+ * to have set the chip up as a clock (turning on the oscillator and
+ * setting the date and time), Linux can ignore the non-clock features.
+ * That's a natural job for a factory or repair bench.
+ */
+enum ds_type {
+	ds_1307,
+	ds_1338,
+	last_ds_type /* always last */
+};
+
+/* RTC registers don't differ much, except for the century flag */
+#define DS1307_REG_SECS		0x00	/* 00-59 */
+#	define DS1307_BIT_CH		0x80
+#	define DS1340_BIT_nEOSC		0x80
+#define DS1307_REG_MIN		0x01	/* 00-59 */
+#define DS1307_REG_HOUR		0x02	/* 00-23, or 1-12{am,pm} */
+#	define DS1307_BIT_12HR		0x40	/* in REG_HOUR */
+#	define DS1307_BIT_PM		0x20	/* in REG_HOUR */
+#	define DS1340_BIT_CENTURY_EN	0x80	/* in REG_HOUR */
+#	define DS1340_BIT_CENTURY	0x40	/* in REG_HOUR */
+#define DS1307_REG_WDAY		0x03	/* 01-07 */
+#define DS1307_REG_MDAY		0x04	/* 01-31 */
+#define DS1307_REG_MONTH	0x05	/* 01-12 */
+#	define DS1337_BIT_CENTURY	0x80	/* in REG_MONTH */
+#define DS1307_REG_YEAR		0x06	/* 00-99 */
+
+/*
+ * Other registers (control, status, alarms, trickle charge, NVRAM, etc)
+ * start at 7, and they differ a LOT. Only control and status matter for
+ * basic RTC date and time functionality; be careful using them.
+ */
+#define DS1307_REG_CONTROL	0x07		/* or ds1338 */
+#	define DS1307_BIT_OUT		0x80
+#	define DS1338_BIT_OSF		0x20
+#	define DS1307_BIT_SQWE		0x10
+#	define DS1307_BIT_RS1		0x02
+#	define DS1307_BIT_RS0		0x01
+
+struct ds1307 {
+	struct rtc_device	rtc;
+	u8			offset; /* register's offset */
+	u8			regs[11];
+	enum ds_type		type;
+	unsigned long		flags;
+	struct i2c_client	*client;
+	s32 (*read_block_data)(const struct i2c_client *client, u8 command,
+			       u8 length, u8 *values);
+	s32 (*write_block_data)(const struct i2c_client *client, u8 command,
+				u8 length, const u8 *values);
+};
+
+static struct platform_device_id ds1307_id[] = {
+	{ "ds1307", ds_1307 },
+	{ "ds1338", ds_1338 },
+	{ "pt7c4338", ds_1307 },
+	{ }
+};
+
+/*----------------------------------------------------------------------*/
+
+#define BLOCK_DATA_MAX_TRIES 10
+
+static s32 ds1307_read_block_data_once(const struct i2c_client *client,
+				       u8 command, u8 length, u8 *values)
+{
+	s32 i, data;
+
+	for (i = 0; i < length; i++) {
+		data = i2c_smbus_read_byte_data(client, command + i);
+		if (data < 0)
+			return data;
+		values[i] = data;
+	}
+	return i;
+}
+
+static s32 ds1307_read_block_data(const struct i2c_client *client, u8 command,
+				  u8 length, u8 *values)
+{
+	u8 oldvalues[255];
+	s32 ret;
+	int tries = 0;
+
+	dev_dbg(&client->dev, "ds1307_read_block_data (length=%d)\n", length);
+	ret = ds1307_read_block_data_once(client, command, length, values);
+	if (ret < 0)
+		return ret;
+	do {
+		if (++tries > BLOCK_DATA_MAX_TRIES) {
+			dev_err(&client->dev,
+				"ds1307_read_block_data failed\n");
+			return -EIO;
+		}
+		memcpy(oldvalues, values, length);
+		ret = ds1307_read_block_data_once(client, command, length,
+						  values);
+		if (ret < 0)
+			return ret;
+	} while (memcmp(oldvalues, values, length));
+	return length;
+}
+
+static s32 ds1307_write_block_data(const struct i2c_client *client, u8 command,
+				   u8 length, const u8 *values)
+{
+	u8 currvalues[255];
+	int tries = 0;
+
+	dev_dbg(&client->dev, "ds1307_write_block_data (length=%d)\n", length);
+	do {
+		s32 i, ret;
+
+		if (++tries > BLOCK_DATA_MAX_TRIES) {
+			dev_err(&client->dev,
+				"ds1307_write_block_data failed\n");
+			return -EIO;
+		}
+		for (i = 0; i < length; i++) {
+			ret = i2c_smbus_write_byte_data(client, command + i,
+							values[i]);
+			if (ret < 0)
+				return ret;
+		}
+		ret = ds1307_read_block_data_once(client, command, length,
+						  currvalues);
+		if (ret < 0)
+			return ret;
+	} while (memcmp(currvalues, values, length));
+	return length;
+}
+
+static inline struct ds1307 *to_ds1307_priv(struct rtc_device *rtcdev)
+{
+	return container_of(rtcdev, struct ds1307, rtc);
+}
+
+static int ds1307_get_time(struct rtc_device *rtcdev, struct rtc_time *t)
+{
+	struct device_d *dev = rtcdev->dev;
+	struct ds1307 *ds1307 = to_ds1307_priv(rtcdev);
+	int		tmp;
+
+	/* read the RTC date and time registers all at once */
+	tmp = ds1307->read_block_data(ds1307->client,
+		ds1307->offset, 7, ds1307->regs);
+	if (tmp != 7) {
+		dev_err(dev, "%s error %d\n", "read", tmp);
+		return -EIO;
+	}
+
+	dev_dbg(dev, "%s: %7ph\n", "read", ds1307->regs);
+
+	t->tm_sec = bcd2bin(ds1307->regs[DS1307_REG_SECS] & 0x7f);
+	t->tm_min = bcd2bin(ds1307->regs[DS1307_REG_MIN] & 0x7f);
+	tmp = ds1307->regs[DS1307_REG_HOUR] & 0x3f;
+	t->tm_hour = bcd2bin(tmp);
+	t->tm_wday = bcd2bin(ds1307->regs[DS1307_REG_WDAY] & 0x07) - 1;
+	t->tm_mday = bcd2bin(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
+	tmp = ds1307->regs[DS1307_REG_MONTH] & 0x1f;
+	t->tm_mon = bcd2bin(tmp) - 1;
+
+	/* assume 20YY not 19YY, and ignore DS1337_BIT_CENTURY */
+	t->tm_year = bcd2bin(ds1307->regs[DS1307_REG_YEAR]) + 100;
+
+	dev_dbg(dev, "%s secs=%d, mins=%d, "
+		"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
+		"read", t->tm_sec, t->tm_min,
+		t->tm_hour, t->tm_mday,
+		t->tm_mon, t->tm_year, t->tm_wday);
+
+	/* initial clock setting can be undefined */
+	return rtc_valid_tm(t);
+}
+
+static int ds1307_set_time(struct rtc_device *rtcdev, struct rtc_time *t)
+{
+	struct device_d *dev = rtcdev->dev;
+	struct ds1307 *ds1307 = to_ds1307_priv(rtcdev);
+	int		result;
+	int		tmp;
+	u8		*buf = ds1307->regs;
+
+	dev_dbg(dev, "%s secs=%d, mins=%d, "
+		"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
+		"write", t->tm_sec, t->tm_min,
+		t->tm_hour, t->tm_mday,
+		t->tm_mon, t->tm_year, t->tm_wday);
+
+	buf[DS1307_REG_SECS] = bin2bcd(t->tm_sec);
+	buf[DS1307_REG_MIN] = bin2bcd(t->tm_min);
+	buf[DS1307_REG_HOUR] = bin2bcd(t->tm_hour);
+	buf[DS1307_REG_WDAY] = bin2bcd(t->tm_wday + 1);
+	buf[DS1307_REG_MDAY] = bin2bcd(t->tm_mday);
+	buf[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
+
+	/* assume 20YY not 19YY */
+	tmp = t->tm_year - 100;
+	buf[DS1307_REG_YEAR] = bin2bcd(tmp);
+
+	dev_dbg(dev, "%s: %7ph\n", "write", buf);
+
+	result = ds1307->write_block_data(ds1307->client,
+		ds1307->offset, 7, buf);
+	if (result < 0) {
+		dev_err(dev, "%s error %d\n", "write", result);
+		return result;
+	}
+	return 0;
+}
+
+static const struct rtc_class_ops ds13xx_rtc_ops = {
+	.read_time	= ds1307_get_time,
+	.set_time	= ds1307_set_time,
+};
+
+static int ds1307_probe(struct device_d *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct ds1307		*ds1307;
+	int			err = -ENODEV;
+	int			tmp;
+	unsigned char		*buf;
+	unsigned long driver_data;
+
+	ds1307 = xzalloc(sizeof(struct ds1307));
+
+	err = dev_get_drvdata(dev, &driver_data);
+	if (err)
+		goto exit;
+
+	ds1307->client = client;
+	ds1307->type = driver_data;
+
+	buf = ds1307->regs;
+
+	ds1307->read_block_data = ds1307_read_block_data;
+	ds1307->write_block_data = ds1307_write_block_data;
+
+read_rtc:
+	/* read RTC registers */
+	tmp = ds1307->read_block_data(client, ds1307->offset, 8, buf);
+	if (tmp != 8) {
+		dev_dbg(&client->dev, "read error %d\n", tmp);
+		err = -EIO;
+		goto exit;
+	}
+
+	/*
+	 * minimal sanity checking; some chips (like DS1340) don't
+	 * specify the extra bits as must-be-zero, but there are
+	 * still a few values that are clearly out-of-range.
+	 */
+	tmp = ds1307->regs[DS1307_REG_SECS];
+	switch (ds1307->type) {
+	case ds_1307:
+		/* clock halted?  turn it on, so clock can tick. */
+		if (tmp & DS1307_BIT_CH) {
+			i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
+			dev_warn(&client->dev, "SET TIME!\n");
+			goto read_rtc;
+		}
+		break;
+	case ds_1338:
+		/* clock halted?  turn it on, so clock can tick. */
+		if (tmp & DS1307_BIT_CH)
+			i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
+
+		/* oscillator fault?  clear flag, and warn */
+		if (ds1307->regs[DS1307_REG_CONTROL] & DS1338_BIT_OSF) {
+			i2c_smbus_write_byte_data(client, DS1307_REG_CONTROL,
+					ds1307->regs[DS1307_REG_CONTROL]
+					& ~DS1338_BIT_OSF);
+			dev_warn(&client->dev, "SET TIME!\n");
+			goto read_rtc;
+		}
+		break;
+	default:
+		break;
+	}
+
+	tmp = ds1307->regs[DS1307_REG_HOUR];
+	switch (ds1307->type) {
+	default:
+		if (!(tmp & DS1307_BIT_12HR))
+			break;
+
+		/*
+		 * Be sure we're in 24 hour mode.  Multi-master systems
+		 * take note...
+		 */
+		tmp = bcd2bin(tmp & 0x1f);
+		if (tmp == 12)
+			tmp = 0;
+		if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
+			tmp += 12;
+		i2c_smbus_write_byte_data(client,
+				ds1307->offset + DS1307_REG_HOUR,
+				bin2bcd(tmp));
+	}
+
+	ds1307->rtc.ops = &ds13xx_rtc_ops;
+	ds1307->rtc.dev = dev;
+
+	err = rtc_register(&ds1307->rtc);
+
+exit:
+	return err;
+}
+
+static struct driver_d ds1307_driver = {
+	.name	= "rtc-ds1307",
+	.probe		= ds1307_probe,
+	.id_table	= ds1307_id,
+};
+
+static int __init ds1307_init(void)
+{
+	return i2c_driver_register(&ds1307_driver);
+}
+device_initcall(ds1307_init);