1 files changed, 429 insertions, 178 deletions

diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index c4ec5c158aa..f03d5ba96db 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -4,6 +4,7 @@
  *  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
@@ -17,10 +18,10 @@
 #include <linux/string.h>
 #include <linux/rtc.h>
 #include <linux/bcd.h>
+#include <linux/rtc/ds1307.h>
 
-
-
-/* We can't determine type by probing, but if we expect pre-Linux code
+/*
+ * 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.
@@ -34,8 +35,10 @@ enum ds_type {
 	ds_1388,
 	ds_3231,
 	m41t00,
+	mcp7941x,
 	rx_8025,
-	// rs5c372 too?  different address...
+	last_ds_type /* always last */
+	/* rs5c372 too?  different address... */
 };
 
 
@@ -43,6 +46,7 @@ enum ds_type {
 #define DS1307_REG_SECS		0x00	/* 00-59 */
 #	define DS1307_BIT_CH		0x80
 #	define DS1340_BIT_nEOSC		0x80
+#	define MCP7941X_BIT_ST		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 */
@@ -50,12 +54,14 @@ enum ds_type {
 #	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 MCP7941X_BIT_VBATEN	0x08
 #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)
+/*
+ * 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.
  */
@@ -86,7 +92,8 @@ enum ds_type {
 #	define DS1337_BIT_A2I		0x02
 #	define DS1337_BIT_A1I		0x01
 #define DS1339_REG_ALARM1_SECS	0x07
-#define DS1339_REG_TRICKLE	0x10
+
+#define DS13XX_TRICKLE_CHARGER_MAGIC	0xa0
 
 #define RX8025_REG_CTRL1	0x0e
 #	define RX8025_BIT_2412		0x20
@@ -99,6 +106,8 @@ enum ds_type {
 struct ds1307 {
 	u8			offset; /* register's offset */
 	u8			regs[11];
+	u16			nvram_offset;
+	struct bin_attribute	*nvram;
 	enum ds_type		type;
 	unsigned long		flags;
 #define HAS_NVRAM	0		/* bit 0 == sysfs file active */
@@ -106,39 +115,51 @@ struct ds1307 {
 	struct i2c_client	*client;
 	struct rtc_device	*rtc;
 	struct work_struct	work;
-	s32 (*read_block_data)(struct i2c_client *client, u8 command,
+	s32 (*read_block_data)(const struct i2c_client *client, u8 command,
 			       u8 length, u8 *values);
-	s32 (*write_block_data)(struct i2c_client *client, u8 command,
+	s32 (*write_block_data)(const struct i2c_client *client, u8 command,
 				u8 length, const u8 *values);
 };
 
 struct chip_desc {
-	unsigned		nvram56:1;
 	unsigned		alarm:1;
+	u16			nvram_offset;
+	u16			nvram_size;
+	u16			trickle_charger_reg;
 };
 
-static const struct chip_desc chips[] = {
-[ds_1307] = {
-	.nvram56	= 1,
-},
-[ds_1337] = {
-	.alarm		= 1,
-},
-[ds_1338] = {
-	.nvram56	= 1,
-},
-[ds_1339] = {
-	.alarm		= 1,
-},
-[ds_1340] = {
-},
-[ds_3231] = {
-	.alarm		= 1,
-},
-[m41t00] = {
-},
-[rx_8025] = {
-}, };
+static const struct chip_desc chips[last_ds_type] = {
+	[ds_1307] = {
+		.nvram_offset	= 8,
+		.nvram_size	= 56,
+	},
+	[ds_1337] = {
+		.alarm		= 1,
+	},
+	[ds_1338] = {
+		.nvram_offset	= 8,
+		.nvram_size	= 56,
+	},
+	[ds_1339] = {
+		.alarm		= 1,
+		.trickle_charger_reg = 0x10,
+	},
+	[ds_1340] = {
+		.trickle_charger_reg = 0x08,
+	},
+	[ds_1388] = {
+		.trickle_charger_reg = 0x0a,
+	},
+	[ds_3231] = {
+		.alarm		= 1,
+	},
+	[mcp7941x] = {
+		.alarm		= 1,
+		/* this is battery backed SRAM */
+		.nvram_offset	= 0x20,
+		.nvram_size	= 0x40,
+	},
+};
 
 static const struct i2c_device_id ds1307_id[] = {
 	{ "ds1307", ds_1307 },
@@ -149,6 +170,8 @@ static const struct i2c_device_id ds1307_id[] = {
 	{ "ds1340", ds_1340 },
 	{ "ds3231", ds_3231 },
 	{ "m41t00", m41t00 },
+	{ "mcp7941x", mcp7941x },
+	{ "pt7c4338", ds_1307 },
 	{ "rx8025", rx_8025 },
 	{ }
 };
@@ -158,8 +181,8 @@ MODULE_DEVICE_TABLE(i2c, ds1307_id);
 
 #define BLOCK_DATA_MAX_TRIES 10
 
-static s32 ds1307_read_block_data_once(struct i2c_client *client, u8 command,
-				  u8 length, u8 *values)
+static s32 ds1307_read_block_data_once(const struct i2c_client *client,
+				       u8 command, u8 length, u8 *values)
 {
 	s32 i, data;
 
@@ -172,10 +195,10 @@ static s32 ds1307_read_block_data_once(struct i2c_client *client, u8 command,
 	return i;
 }
 
-static s32 ds1307_read_block_data(struct i2c_client *client, u8 command,
+static s32 ds1307_read_block_data(const struct i2c_client *client, u8 command,
 				  u8 length, u8 *values)
 {
-	u8 oldvalues[I2C_SMBUS_BLOCK_MAX];
+	u8 oldvalues[255];
 	s32 ret;
 	int tries = 0;
 
@@ -198,10 +221,10 @@ static s32 ds1307_read_block_data(struct i2c_client *client, u8 command,
 	return length;
 }
 
-static s32 ds1307_write_block_data(struct i2c_client *client, u8 command,
+static s32 ds1307_write_block_data(const struct i2c_client *client, u8 command,
 				   u8 length, const u8 *values)
 {
-	u8 currvalues[I2C_SMBUS_BLOCK_MAX];
+	u8 currvalues[255];
 	int tries = 0;
 
 	dev_dbg(&client->dev, "ds1307_write_block_data (length=%d)\n", length);
@@ -229,6 +252,57 @@ static s32 ds1307_write_block_data(struct i2c_client *client, u8 command,
 
 /*----------------------------------------------------------------------*/
 
+/* These RTC devices are not designed to be connected to a SMbus adapter.
+   SMbus limits block operations length to 32 bytes, whereas it's not
+   limited on I2C buses. As a result, accesses may exceed 32 bytes;
+   in that case, split them into smaller blocks */
+
+static s32 ds1307_native_smbus_write_block_data(const struct i2c_client *client,
+				u8 command, u8 length, const u8 *values)
+{
+	u8 suboffset = 0;
+
+	if (length <= I2C_SMBUS_BLOCK_MAX)
+		return i2c_smbus_write_i2c_block_data(client,
+					command, length, values);
+
+	while (suboffset < length) {
+		s32 retval = i2c_smbus_write_i2c_block_data(client,
+				command + suboffset,
+				min(I2C_SMBUS_BLOCK_MAX, length - suboffset),
+				values + suboffset);
+		if (retval < 0)
+			return retval;
+
+		suboffset += I2C_SMBUS_BLOCK_MAX;
+	}
+	return length;
+}
+
+static s32 ds1307_native_smbus_read_block_data(const struct i2c_client *client,
+				u8 command, u8 length, u8 *values)
+{
+	u8 suboffset = 0;
+
+	if (length <= I2C_SMBUS_BLOCK_MAX)
+		return i2c_smbus_read_i2c_block_data(client,
+					command, length, values);
+
+	while (suboffset < length) {
+		s32 retval = i2c_smbus_read_i2c_block_data(client,
+				command + suboffset,
+				min(I2C_SMBUS_BLOCK_MAX, length - suboffset),
+				values + suboffset);
+		if (retval < 0)
+			return retval;
+
+		suboffset += I2C_SMBUS_BLOCK_MAX;
+	}
+	return length;
+}
+
+/*----------------------------------------------------------------------*/
+
 /*
  * The IRQ logic includes a "real" handler running in IRQ context just
  * long enough to schedule this workqueue entry.   We need a task context
@@ -301,12 +375,7 @@ static int ds1307_get_time(struct device *dev, struct rtc_time *t)
 		return -EIO;
 	}
 
-	dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
-			"read",
-			ds1307->regs[0], ds1307->regs[1],
-			ds1307->regs[2], ds1307->regs[3],
-			ds1307->regs[4], ds1307->regs[5],
-			ds1307->regs[6]);
+	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);
@@ -364,13 +433,20 @@ static int ds1307_set_time(struct device *dev, struct rtc_time *t)
 		buf[DS1307_REG_HOUR] |= DS1340_BIT_CENTURY_EN
 				| DS1340_BIT_CENTURY;
 		break;
+	case mcp7941x:
+		/*
+		 * these bits were cleared when preparing the date/time
+		 * values and need to be set again before writing the
+		 * buffer out to the device.
+		 */
+		buf[DS1307_REG_SECS] |= MCP7941X_BIT_ST;
+		buf[DS1307_REG_WDAY] |= MCP7941X_BIT_VBATEN;
+		break;
 	default:
 		break;
 	}
 
-	dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
-		"write", buf[0], buf[1], buf[2], buf[3],
-		buf[4], buf[5], buf[6]);
+	dev_dbg(dev, "%s: %7ph\n", "write", buf);
 
 	result = ds1307->write_block_data(ds1307->client,
 		ds1307->offset, 7, buf);
@@ -406,7 +482,8 @@ static int ds1337_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 			ds1307->regs[6], ds1307->regs[7],
 			ds1307->regs[8]);
 
-	/* report alarm time (ALARM1); assume 24 hour and day-of-month modes,
+	/*
+	 * report alarm time (ALARM1); assume 24 hour and day-of-month modes,
 	 * and that all four fields are checked matches
 	 */
 	t->time.tm_sec = bcd2bin(ds1307->regs[0] & 0x7f);
@@ -434,7 +511,7 @@ static int ds1337_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 
 static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 {
-	struct i2c_client       *client = to_i2c_client(dev);
+	struct i2c_client	*client = to_i2c_client(dev);
 	struct ds1307		*ds1307 = i2c_get_clientdata(client);
 	unsigned char		*buf = ds1307->regs;
 	u8			control, status;
@@ -495,68 +572,216 @@ static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 	return 0;
 }
 
-static int ds1307_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
+static int ds1307_alarm_irq_enable(struct device *dev, unsigned int enabled)
 {
 	struct i2c_client	*client = to_i2c_client(dev);
 	struct ds1307		*ds1307 = i2c_get_clientdata(client);
 	int			ret;
 
-	switch (cmd) {
-	case RTC_AIE_OFF:
-		if (!test_bit(HAS_ALARM, &ds1307->flags))
-			return -ENOTTY;
+	if (!test_bit(HAS_ALARM, &ds1307->flags))
+		return -ENOTTY;
 
-		ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
-		if (ret < 0)
-			return ret;
+	ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
+	if (ret < 0)
+		return ret;
 
+	if (enabled)
+		ret |= DS1337_BIT_A1IE;
+	else
 		ret &= ~DS1337_BIT_A1IE;
 
-		ret = i2c_smbus_write_byte_data(client,
-						DS1337_REG_CONTROL, ret);
-		if (ret < 0)
-			return ret;
+	ret = i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, ret);
+	if (ret < 0)
+		return ret;
 
-		break;
+	return 0;
+}
 
-	case RTC_AIE_ON:
-		if (!test_bit(HAS_ALARM, &ds1307->flags))
-			return -ENOTTY;
+static const struct rtc_class_ops ds13xx_rtc_ops = {
+	.read_time	= ds1307_get_time,
+	.set_time	= ds1307_set_time,
+	.read_alarm	= ds1337_read_alarm,
+	.set_alarm	= ds1337_set_alarm,
+	.alarm_irq_enable = ds1307_alarm_irq_enable,
+};
 
-		ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
-		if (ret < 0)
-			return ret;
+/*----------------------------------------------------------------------*/
 
-		ret |= DS1337_BIT_A1IE;
+/*
+ * Alarm support for mcp7941x devices.
+ */
 
-		ret = i2c_smbus_write_byte_data(client,
-						DS1337_REG_CONTROL, ret);
-		if (ret < 0)
-			return ret;
+#define MCP7941X_REG_CONTROL		0x07
+#	define MCP7941X_BIT_ALM0_EN	0x10
+#	define MCP7941X_BIT_ALM1_EN	0x20
+#define MCP7941X_REG_ALARM0_BASE	0x0a
+#define MCP7941X_REG_ALARM0_CTRL	0x0d
+#define MCP7941X_REG_ALARM1_BASE	0x11
+#define MCP7941X_REG_ALARM1_CTRL	0x14
+#	define MCP7941X_BIT_ALMX_IF	(1 << 3)
+#	define MCP7941X_BIT_ALMX_C0	(1 << 4)
+#	define MCP7941X_BIT_ALMX_C1	(1 << 5)
+#	define MCP7941X_BIT_ALMX_C2	(1 << 6)
+#	define MCP7941X_BIT_ALMX_POL	(1 << 7)
+#	define MCP7941X_MSK_ALMX_MATCH	(MCP7941X_BIT_ALMX_C0 | \
+					 MCP7941X_BIT_ALMX_C1 | \
+					 MCP7941X_BIT_ALMX_C2)
+
+static void mcp7941x_work(struct work_struct *work)
+{
+	struct ds1307 *ds1307 = container_of(work, struct ds1307, work);
+	struct i2c_client *client = ds1307->client;
+	int reg, ret;
 
-		break;
+	mutex_lock(&ds1307->rtc->ops_lock);
 
-	default:
-		return -ENOIOCTLCMD;
-	}
+	/* Check and clear alarm 0 interrupt flag. */
+	reg = i2c_smbus_read_byte_data(client, MCP7941X_REG_ALARM0_CTRL);
+	if (reg < 0)
+		goto out;
+	if (!(reg & MCP7941X_BIT_ALMX_IF))
+		goto out;
+	reg &= ~MCP7941X_BIT_ALMX_IF;
+	ret = i2c_smbus_write_byte_data(client, MCP7941X_REG_ALARM0_CTRL, reg);
+	if (ret < 0)
+		goto out;
+
+	/* Disable alarm 0. */
+	reg = i2c_smbus_read_byte_data(client, MCP7941X_REG_CONTROL);
+	if (reg < 0)
+		goto out;
+	reg &= ~MCP7941X_BIT_ALM0_EN;
+	ret = i2c_smbus_write_byte_data(client, MCP7941X_REG_CONTROL, reg);
+	if (ret < 0)
+		goto out;
+
+	rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
+
+out:
+	if (test_bit(HAS_ALARM, &ds1307->flags))
+		enable_irq(client->irq);
+	mutex_unlock(&ds1307->rtc->ops_lock);
+}
+
+static int mcp7941x_read_alarm(struct device *dev, struct rtc_wkalrm *t)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct ds1307 *ds1307 = i2c_get_clientdata(client);
+	u8 *regs = ds1307->regs;
+	int ret;
+
+	if (!test_bit(HAS_ALARM, &ds1307->flags))
+		return -EINVAL;
+
+	/* Read control and alarm 0 registers. */
+	ret = ds1307->read_block_data(client, MCP7941X_REG_CONTROL, 10, regs);
+	if (ret < 0)
+		return ret;
+
+	t->enabled = !!(regs[0] & MCP7941X_BIT_ALM0_EN);
+
+	/* Report alarm 0 time assuming 24-hour and day-of-month modes. */
+	t->time.tm_sec = bcd2bin(ds1307->regs[3] & 0x7f);
+	t->time.tm_min = bcd2bin(ds1307->regs[4] & 0x7f);
+	t->time.tm_hour = bcd2bin(ds1307->regs[5] & 0x3f);
+	t->time.tm_wday = bcd2bin(ds1307->regs[6] & 0x7) - 1;
+	t->time.tm_mday = bcd2bin(ds1307->regs[7] & 0x3f);
+	t->time.tm_mon = bcd2bin(ds1307->regs[8] & 0x1f) - 1;
+	t->time.tm_year = -1;
+	t->time.tm_yday = -1;
+	t->time.tm_isdst = -1;
+
+	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
+		"enabled=%d polarity=%d irq=%d match=%d\n", __func__,
+		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
+		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon, t->enabled,
+		!!(ds1307->regs[6] & MCP7941X_BIT_ALMX_POL),
+		!!(ds1307->regs[6] & MCP7941X_BIT_ALMX_IF),
+		(ds1307->regs[6] & MCP7941X_MSK_ALMX_MATCH) >> 4);
 
 	return 0;
 }
 
-static const struct rtc_class_ops ds13xx_rtc_ops = {
+static int mcp7941x_set_alarm(struct device *dev, struct rtc_wkalrm *t)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct ds1307 *ds1307 = i2c_get_clientdata(client);
+	unsigned char *regs = ds1307->regs;
+	int ret;
+
+	if (!test_bit(HAS_ALARM, &ds1307->flags))
+		return -EINVAL;
+
+	dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
+		"enabled=%d pending=%d\n", __func__,
+		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
+		t->time.tm_wday, t->time.tm_mday, t->time.tm_mon,
+		t->enabled, t->pending);
+
+	/* Read control and alarm 0 registers. */
+	ret = ds1307->read_block_data(client, MCP7941X_REG_CONTROL, 10, regs);
+	if (ret < 0)
+		return ret;
+
+	/* Set alarm 0, using 24-hour and day-of-month modes. */
+	regs[3] = bin2bcd(t->time.tm_sec);
+	regs[4] = bin2bcd(t->time.tm_min);
+	regs[5] = bin2bcd(t->time.tm_hour);
+	regs[6] = bin2bcd(t->time.tm_wday) + 1;
+	regs[7] = bin2bcd(t->time.tm_mday);
+	regs[8] = bin2bcd(t->time.tm_mon) + 1;
+
+	/* Clear the alarm 0 interrupt flag. */
+	regs[6] &= ~MCP7941X_BIT_ALMX_IF;
+	/* Set alarm match: second, minute, hour, day, date, month. */
+	regs[6] |= MCP7941X_MSK_ALMX_MATCH;
+
+	if (t->enabled)
+		regs[0] |= MCP7941X_BIT_ALM0_EN;
+	else
+		regs[0] &= ~MCP7941X_BIT_ALM0_EN;
+
+	ret = ds1307->write_block_data(client, MCP7941X_REG_CONTROL, 10, regs);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int mcp7941x_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct ds1307 *ds1307 = i2c_get_clientdata(client);
+	int reg;
+
+	if (!test_bit(HAS_ALARM, &ds1307->flags))
+		return -EINVAL;
+
+	reg = i2c_smbus_read_byte_data(client, MCP7941X_REG_CONTROL);
+	if (reg < 0)
+		return reg;
+
+	if (enabled)
+		reg |= MCP7941X_BIT_ALM0_EN;
+	else
+		reg &= ~MCP7941X_BIT_ALM0_EN;
+
+	return i2c_smbus_write_byte_data(client, MCP7941X_REG_CONTROL, reg);
+}
+
+static const struct rtc_class_ops mcp7941x_rtc_ops = {
 	.read_time	= ds1307_get_time,
 	.set_time	= ds1307_set_time,
-	.read_alarm	= ds1337_read_alarm,
-	.set_alarm	= ds1337_set_alarm,
-	.ioctl		= ds1307_ioctl,
+	.read_alarm	= mcp7941x_read_alarm,
+	.set_alarm	= mcp7941x_set_alarm,
+	.alarm_irq_enable = mcp7941x_alarm_irq_enable,
 };
 
 /*----------------------------------------------------------------------*/
 
-#define NVRAM_SIZE	56
-
 static ssize_t
-ds1307_nvram_read(struct kobject *kobj, struct bin_attribute *attr,
+ds1307_nvram_read(struct file *filp, struct kobject *kobj,
+		struct bin_attribute *attr,
 		char *buf, loff_t off, size_t count)
 {
 	struct i2c_client	*client;
@@ -566,21 +791,23 @@ ds1307_nvram_read(struct kobject *kobj, struct bin_attribute *attr,
 	client = kobj_to_i2c_client(kobj);
 	ds1307 = i2c_get_clientdata(client);
 
-	if (unlikely(off >= NVRAM_SIZE))
+	if (unlikely(off >= ds1307->nvram->size))
 		return 0;
-	if ((off + count) > NVRAM_SIZE)
-		count = NVRAM_SIZE - off;
+	if ((off + count) > ds1307->nvram->size)
+		count = ds1307->nvram->size - off;
 	if (unlikely(!count))
 		return count;
 
-	result = ds1307->read_block_data(client, 8 + off, count, buf);
+	result = ds1307->read_block_data(client, ds1307->nvram_offset + off,
+								count, buf);
 	if (result < 0)
 		dev_err(&client->dev, "%s error %d\n", "nvram read", result);
 	return result;
 }
 
 static ssize_t
-ds1307_nvram_write(struct kobject *kobj, struct bin_attribute *attr,
+ds1307_nvram_write(struct file *filp, struct kobject *kobj,
+		struct bin_attribute *attr,
 		char *buf, loff_t off, size_t count)
 {
 	struct i2c_client	*client;
@@ -590,14 +817,15 @@ ds1307_nvram_write(struct kobject *kobj, struct bin_attribute *attr,
 	client = kobj_to_i2c_client(kobj);
 	ds1307 = i2c_get_clientdata(client);
 
-	if (unlikely(off >= NVRAM_SIZE))
+	if (unlikely(off >= ds1307->nvram->size))
 		return -EFBIG;
-	if ((off + count) > NVRAM_SIZE)
-		count = NVRAM_SIZE - off;
+	if ((off + count) > ds1307->nvram->size)
+		count = ds1307->nvram->size - off;
 	if (unlikely(!count))
 		return count;
 
-	result = ds1307->write_block_data(client, 8 + off, count, buf);
+	result = ds1307->write_block_data(client, ds1307->nvram_offset + off,
+								count, buf);
 	if (result < 0) {
 		dev_err(&client->dev, "%s error %d\n", "nvram write", result);
 		return result;
@@ -605,54 +833,47 @@ ds1307_nvram_write(struct kobject *kobj, struct bin_attribute *attr,
 	return count;
 }
 
-static struct bin_attribute nvram = {
-	.attr = {
-		.name	= "nvram",
-		.mode	= S_IRUGO | S_IWUSR,
-	},
-
-	.read	= ds1307_nvram_read,
-	.write	= ds1307_nvram_write,
-	.size	= NVRAM_SIZE,
-};
-
 /*----------------------------------------------------------------------*/
 
-static struct i2c_driver ds1307_driver;
-
-static int __devinit ds1307_probe(struct i2c_client *client,
-				  const struct i2c_device_id *id)
+static int ds1307_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
 {
 	struct ds1307		*ds1307;
 	int			err = -ENODEV;
 	int			tmp;
 	const struct chip_desc	*chip = &chips[id->driver_data];
 	struct i2c_adapter	*adapter = to_i2c_adapter(client->dev.parent);
-	int			want_irq = false;
+	bool			want_irq = false;
 	unsigned char		*buf;
+	struct ds1307_platform_data *pdata = dev_get_platdata(&client->dev);
 	static const int	bbsqi_bitpos[] = {
 		[ds_1337] = 0,
 		[ds_1339] = DS1339_BIT_BBSQI,
 		[ds_3231] = DS3231_BIT_BBSQW,
 	};
+	const struct rtc_class_ops *rtc_ops = &ds13xx_rtc_ops;
 
 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)
 	    && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
 		return -EIO;
 
-	if (!(ds1307 = kzalloc(sizeof(struct ds1307), GFP_KERNEL)))
+	ds1307 = devm_kzalloc(&client->dev, sizeof(struct ds1307), GFP_KERNEL);
+	if (!ds1307)
 		return -ENOMEM;
 
 	i2c_set_clientdata(client, ds1307);
 
 	ds1307->client	= client;
 	ds1307->type	= id->driver_data;
-	ds1307->offset	= 0;
+
+	if (pdata && pdata->trickle_charger_setup && chip->trickle_charger_reg)
+		i2c_smbus_write_byte_data(client, chip->trickle_charger_reg,
+			DS13XX_TRICKLE_CHARGER_MAGIC | pdata->trickle_charger_setup);
 
 	buf = ds1307->regs;
 	if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK)) {
-		ds1307->read_block_data = i2c_smbus_read_i2c_block_data;
-		ds1307->write_block_data = i2c_smbus_write_i2c_block_data;
+		ds1307->read_block_data = ds1307_native_smbus_read_block_data;
+		ds1307->write_block_data = ds1307_native_smbus_write_block_data;
 	} else {
 		ds1307->read_block_data = ds1307_read_block_data;
 		ds1307->write_block_data = ds1307_write_block_data;
@@ -662,32 +883,32 @@ static int __devinit ds1307_probe(struct i2c_client *client,
 	case ds_1337:
 	case ds_1339:
 	case ds_3231:
-		/* has IRQ? */
-		if (ds1307->client->irq > 0 && chip->alarm) {
-			INIT_WORK(&ds1307->work, ds1307_work);
-			want_irq = true;
-		}
 		/* get registers that the "rtc" read below won't read... */
 		tmp = ds1307->read_block_data(ds1307->client,
 				DS1337_REG_CONTROL, 2, buf);
 		if (tmp != 2) {
-			pr_debug("read error %d\n", tmp);
+			dev_dbg(&client->dev, "read error %d\n", tmp);
 			err = -EIO;
-			goto exit_free;
+			goto exit;
 		}
 
 		/* oscillator off?  turn it on, so clock can tick. */
 		if (ds1307->regs[0] & DS1337_BIT_nEOSC)
 			ds1307->regs[0] &= ~DS1337_BIT_nEOSC;
 
-		/* Using IRQ?  Disable the square wave and both alarms.
+		/*
+		 * Using IRQ?  Disable the square wave and both alarms.
 		 * For some variants, be sure alarms can trigger when we're
 		 * running on Vbackup (BBSQI/BBSQW)
 		 */
-		if (want_irq) {
+		if (ds1307->client->irq > 0 && chip->alarm) {
+			INIT_WORK(&ds1307->work, ds1307_work);
+
 			ds1307->regs[0] |= DS1337_BIT_INTCN
 					| bbsqi_bitpos[ds1307->type];
 			ds1307->regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
+
+			want_irq = true;
 		}
 
 		i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
@@ -705,9 +926,9 @@ static int __devinit ds1307_probe(struct i2c_client *client,
 		tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
 				RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
 		if (tmp != 2) {
-			pr_debug("read error %d\n", tmp);
+			dev_dbg(&client->dev, "read error %d\n", tmp);
 			err = -EIO;
-			goto exit_free;
+			goto exit;
 		}
 
 		/* oscillator off?  turn it on, so clock can tick. */
@@ -749,9 +970,9 @@ static int __devinit ds1307_probe(struct i2c_client *client,
 			tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
 					RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
 			if (tmp != 2) {
-				pr_debug("read error %d\n", tmp);
+				dev_dbg(&client->dev, "read error %d\n", tmp);
 				err = -EIO;
-				goto exit_free;
+				goto exit;
 			}
 
 			/* correct hour */
@@ -769,20 +990,28 @@ static int __devinit ds1307_probe(struct i2c_client *client,
 	case ds_1388:
 		ds1307->offset = 1; /* Seconds starts at 1 */
 		break;
+	case mcp7941x:
+		rtc_ops = &mcp7941x_rtc_ops;
+		if (ds1307->client->irq > 0 && chip->alarm) {
+			INIT_WORK(&ds1307->work, mcp7941x_work);
+			want_irq = true;
+		}
+		break;
 	default:
 		break;
 	}
 
 read_rtc:
 	/* read RTC registers */
-	tmp = ds1307->read_block_data(ds1307->client, 0, 8, buf);
+	tmp = ds1307->read_block_data(ds1307->client, ds1307->offset, 8, buf);
 	if (tmp != 8) {
-		pr_debug("read error %d\n", tmp);
+		dev_dbg(&client->dev, "read error %d\n", tmp);
 		err = -EIO;
-		goto exit_free;
+		goto exit;
 	}
 
-	/* minimal sanity checking; some chips (like DS1340) don't
+	/*
+	 * 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.
 	 */
@@ -818,9 +1047,9 @@ read_rtc:
 
 		tmp = i2c_smbus_read_byte_data(client, DS1340_REG_FLAG);
 		if (tmp < 0) {
-			pr_debug("read error %d\n", tmp);
+			dev_dbg(&client->dev, "read error %d\n", tmp);
 			err = -EIO;
-			goto exit_free;
+			goto exit;
 		}
 
 		/* oscillator fault?  clear flag, and warn */
@@ -829,11 +1058,24 @@ read_rtc:
 			dev_warn(&client->dev, "SET TIME!\n");
 		}
 		break;
-	case rx_8025:
-	case ds_1337:
-	case ds_1339:
-	case ds_1388:
-	case ds_3231:
+	case mcp7941x:
+		/* make sure that the backup battery is enabled */
+		if (!(ds1307->regs[DS1307_REG_WDAY] & MCP7941X_BIT_VBATEN)) {
+			i2c_smbus_write_byte_data(client, DS1307_REG_WDAY,
+					ds1307->regs[DS1307_REG_WDAY]
+					| MCP7941X_BIT_VBATEN);
+		}
+
+		/* clock halted?  turn it on, so clock can tick. */
+		if (!(tmp & MCP7941X_BIT_ST)) {
+			i2c_smbus_write_byte_data(client, DS1307_REG_SECS,
+					MCP7941X_BIT_ST);
+			dev_warn(&client->dev, "SET TIME!\n");
+			goto read_rtc;
+		}
+
+		break;
+	default:
 		break;
 	}
 
@@ -841,7 +1083,8 @@ read_rtc:
 	switch (ds1307->type) {
 	case ds_1340:
 	case m41t00:
-		/* NOTE: ignores century bits; fix before deploying
+		/*
+		 * NOTE: ignores century bits; fix before deploying
 		 * systems that will run through year 2100.
 		 */
 		break;
@@ -851,7 +1094,8 @@ read_rtc:
 		if (!(tmp & DS1307_BIT_12HR))
 			break;
 
-		/* Be sure we're in 24 hour mode.  Multi-master systems
+		/*
+		 * Be sure we're in 24 hour mode.  Multi-master systems
 		 * take note...
 		 */
 		tmp = bcd2bin(tmp & 0x1f);
@@ -860,53 +1104,72 @@ read_rtc:
 		if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
 			tmp += 12;
 		i2c_smbus_write_byte_data(client,
-				DS1307_REG_HOUR,
+				ds1307->offset + DS1307_REG_HOUR,
 				bin2bcd(tmp));
 	}
 
-	ds1307->rtc = rtc_device_register(client->name, &client->dev,
-				&ds13xx_rtc_ops, THIS_MODULE);
+	device_set_wakeup_capable(&client->dev, want_irq);
+	ds1307->rtc = devm_rtc_device_register(&client->dev, client->name,
+				rtc_ops, THIS_MODULE);
 	if (IS_ERR(ds1307->rtc)) {
-		err = PTR_ERR(ds1307->rtc);
-		dev_err(&client->dev,
-			"unable to register the class device\n");
-		goto exit_free;
+		return PTR_ERR(ds1307->rtc);
 	}
 
 	if (want_irq) {
 		err = request_irq(client->irq, ds1307_irq, IRQF_SHARED,
 			  ds1307->rtc->name, client);
 		if (err) {
-			dev_err(&client->dev,
-				"unable to request IRQ!\n");
-			goto exit_irq;
-		}
+			client->irq = 0;
+			dev_err(&client->dev, "unable to request IRQ!\n");
+		} else {
 
-		device_set_wakeup_capable(&client->dev, 1);
-		set_bit(HAS_ALARM, &ds1307->flags);
-		dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
+			set_bit(HAS_ALARM, &ds1307->flags);
+			dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
+		}
 	}
 
-	if (chip->nvram56) {
-		err = sysfs_create_bin_file(&client->dev.kobj, &nvram);
-		if (err == 0) {
-			set_bit(HAS_NVRAM, &ds1307->flags);
-			dev_info(&client->dev, "56 bytes nvram\n");
+	if (chip->nvram_size) {
+
+		ds1307->nvram = devm_kzalloc(&client->dev,
+					sizeof(struct bin_attribute),
+					GFP_KERNEL);
+		if (!ds1307->nvram) {
+			dev_err(&client->dev, "cannot allocate memory for nvram sysfs\n");
+		} else {
+
+			ds1307->nvram->attr.name = "nvram";
+			ds1307->nvram->attr.mode = S_IRUGO | S_IWUSR;
+
+			sysfs_bin_attr_init(ds1307->nvram);
+
+			ds1307->nvram->read = ds1307_nvram_read;
+			ds1307->nvram->write = ds1307_nvram_write;
+			ds1307->nvram->size = chip->nvram_size;
+			ds1307->nvram_offset = chip->nvram_offset;
+
+			err = sysfs_create_bin_file(&client->dev.kobj,
+						    ds1307->nvram);
+			if (err) {
+				dev_err(&client->dev,
+					"unable to create sysfs file: %s\n",
+					ds1307->nvram->attr.name);
+			} else {
+				set_bit(HAS_NVRAM, &ds1307->flags);
+				dev_info(&client->dev, "%zu bytes nvram\n",
+					 ds1307->nvram->size);
+			}
 		}
 	}
 
 	return 0;
 
-exit_irq:
-	rtc_device_unregister(ds1307->rtc);
-exit_free:
-	kfree(ds1307);
+exit:
 	return err;
 }
 
-static int __devexit ds1307_remove(struct i2c_client *client)
+static int ds1307_remove(struct i2c_client *client)
 {
-	struct ds1307		*ds1307 = i2c_get_clientdata(client);
+	struct ds1307 *ds1307 = i2c_get_clientdata(client);
 
 	if (test_and_clear_bit(HAS_ALARM, &ds1307->flags)) {
 		free_irq(client->irq, client);
@@ -914,10 +1177,8 @@ static int __devexit ds1307_remove(struct i2c_client *client)
 	}
 
 	if (test_and_clear_bit(HAS_NVRAM, &ds1307->flags))
-		sysfs_remove_bin_file(&client->dev.kobj, &nvram);
+		sysfs_remove_bin_file(&client->dev.kobj, ds1307->nvram);
 
-	rtc_device_unregister(ds1307->rtc);
-	kfree(ds1307);
 	return 0;
 }
 
@@ -927,21 +1188,11 @@ static struct i2c_driver ds1307_driver = {
 		.owner	= THIS_MODULE,
 	},
 	.probe		= ds1307_probe,
-	.remove		= __devexit_p(ds1307_remove),
+	.remove		= ds1307_remove,
 	.id_table	= ds1307_id,
 };
 
-static int __init ds1307_init(void)
-{
-	return i2c_add_driver(&ds1307_driver);
-}
-module_init(ds1307_init);
-
-static void __exit ds1307_exit(void)
-{
-	i2c_del_driver(&ds1307_driver);
-}
-module_exit(ds1307_exit);
+module_i2c_driver(ds1307_driver);
 
 MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
 MODULE_LICENSE("GPL");