drivers/i2c/chips/ds1337.c - kernel/msm-4.9 - Gitiles

 /*
  *  linux/drivers/i2c/chips/ds1337.c
  *
  *  Copyright (C) 2005 James Chapman <jchapman@katalix.com>
  *
  *	based on linux/drivers/acorn/char/pcf8583.c
  *  Copyright (C) 2000 Russell King
  *
  * 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.
  *
  * Driver for Dallas Semiconductor DS1337 and DS1339 real time clock chip
  */

 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/i2c.h>
 #include <linux/string.h>
 #include <linux/rtc.h>		/* get the user-level API */
 #include <linux/bcd.h>
 #include <linux/list.h>

 /* Device registers */
 #define DS1337_REG_HOUR		2
 #define DS1337_REG_DAY		3
 #define DS1337_REG_DATE		4
 #define DS1337_REG_MONTH	5
 #define DS1337_REG_CONTROL	14
 #define DS1337_REG_STATUS	15

 /* FIXME - how do we export these interface constants? */
 #define DS1337_GET_DATE		0
 #define DS1337_SET_DATE		1

 /*
  * Functions declaration
  */
 static unsigned short normal_i2c[] = { 0x68, I2C_CLIENT_END };

 I2C_CLIENT_INSMOD_1(ds1337);

 static int ds1337_attach_adapter(struct i2c_adapter *adapter);
 static int ds1337_detect(struct i2c_adapter *adapter, int address, int kind);
 static void ds1337_init_client(struct i2c_client *client);
 static int ds1337_detach_client(struct i2c_client *client);
 static int ds1337_command(struct i2c_client *client, unsigned int cmd,
 			  void *arg);

 /*
  * Driver data (common to all clients)
  */
 static struct i2c_driver ds1337_driver = {
 	.driver = {
 		.name	= "ds1337",
 	},
 	.attach_adapter	= ds1337_attach_adapter,
 	.detach_client	= ds1337_detach_client,
 	.command	= ds1337_command,
 };

 /*
  * Client data (each client gets its own)
  */
 struct ds1337_data {
 	struct i2c_client client;
 	struct list_head list;
 };

 /*
  * Internal variables
  */
 static LIST_HEAD(ds1337_clients);

 static inline int ds1337_read(struct i2c_client *client, u8 reg, u8 *value)
 {
 	s32 tmp = i2c_smbus_read_byte_data(client, reg);

 	if (tmp < 0)
 		return -EIO;

 	*value = tmp;

 	return 0;
 }

 /*
  * Chip access functions
  */
 static int ds1337_get_datetime(struct i2c_client *client, struct rtc_time *dt)
 {
 	int result;
 	u8 buf[7];
 	u8 val;
 	struct i2c_msg msg[2];
 	u8 offs = 0;

 	if (!dt) {
 		dev_dbg(&client->dev, "%s: EINVAL: dt=NULL\n", __FUNCTION__);
 		return -EINVAL;
 	}

 	msg[0].addr = client->addr;
 	msg[0].flags = 0;
 	msg[0].len = 1;
 	msg[0].buf = &offs;

 	msg[1].addr = client->addr;
 	msg[1].flags = I2C_M_RD;
 	msg[1].len = sizeof(buf);
 	msg[1].buf = &buf[0];

 	result = i2c_transfer(client->adapter, msg, 2);

 	dev_dbg(&client->dev, "%s: [%d] %02x %02x %02x %02x %02x %02x %02x\n",
 		__FUNCTION__, result, buf[0], buf[1], buf[2], buf[3],
 		buf[4], buf[5], buf[6]);

 	if (result == 2) {
 		dt->tm_sec = BCD2BIN(buf[0]);
 		dt->tm_min = BCD2BIN(buf[1]);
 		val = buf[2] & 0x3f;
 		dt->tm_hour = BCD2BIN(val);
 		dt->tm_wday = BCD2BIN(buf[3]) - 1;
 		dt->tm_mday = BCD2BIN(buf[4]);
 		val = buf[5] & 0x7f;
 		dt->tm_mon = BCD2BIN(val) - 1;
 		dt->tm_year = BCD2BIN(buf[6]);
 		if (buf[5] & 0x80)
 			dt->tm_year += 100;

 		dev_dbg(&client->dev, "%s: secs=%d, mins=%d, "
 			"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
 			__FUNCTION__, dt->tm_sec, dt->tm_min,
 			dt->tm_hour, dt->tm_mday,
 			dt->tm_mon, dt->tm_year, dt->tm_wday);

 		return 0;
 	}

 	dev_err(&client->dev, "error reading data! %d\n", result);
 	return -EIO;
 }

 static int ds1337_set_datetime(struct i2c_client *client, struct rtc_time *dt)
 {
 	int result;
 	u8 buf[8];
 	u8 val;
 	struct i2c_msg msg[1];

 	if (!dt) {
 		dev_dbg(&client->dev, "%s: EINVAL: dt=NULL\n", __FUNCTION__);
 		return -EINVAL;
 	}

 	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 		"mday=%d, mon=%d, year=%d, wday=%d\n", __FUNCTION__,
 		dt->tm_sec, dt->tm_min, dt->tm_hour,
 		dt->tm_mday, dt->tm_mon, dt->tm_year, dt->tm_wday);

 	buf[0] = 0;		/* reg offset */
 	buf[1] = BIN2BCD(dt->tm_sec);
 	buf[2] = BIN2BCD(dt->tm_min);
 	buf[3] = BIN2BCD(dt->tm_hour);
 	buf[4] = BIN2BCD(dt->tm_wday + 1);
 	buf[5] = BIN2BCD(dt->tm_mday);
 	buf[6] = BIN2BCD(dt->tm_mon + 1);
 	val = dt->tm_year;
 	if (val >= 100) {
 		val -= 100;
 		buf[6] |= (1 << 7);
 	}
 	buf[7] = BIN2BCD(val);

 	msg[0].addr = client->addr;
 	msg[0].flags = 0;
 	msg[0].len = sizeof(buf);
 	msg[0].buf = &buf[0];

 	result = i2c_transfer(client->adapter, msg, 1);
 	if (result == 1)
 		return 0;

 	dev_err(&client->dev, "error writing data! %d\n", result);
 	return -EIO;
 }

 static int ds1337_command(struct i2c_client *client, unsigned int cmd,
 			  void *arg)
 {
 	dev_dbg(&client->dev, "%s: cmd=%d\n", __FUNCTION__, cmd);

 	switch (cmd) {
 	case DS1337_GET_DATE:
 		return ds1337_get_datetime(client, arg);

 	case DS1337_SET_DATE:
 		return ds1337_set_datetime(client, arg);

 	default:
 		return -EINVAL;
 	}
 }

 /*
  * Public API for access to specific device. Useful for low-level
  * RTC access from kernel code.
  */
 int ds1337_do_command(int bus, int cmd, void *arg)
 {
 	struct list_head *walk;
 	struct list_head *tmp;
 	struct ds1337_data *data;

 	list_for_each_safe(walk, tmp, &ds1337_clients) {
 		data = list_entry(walk, struct ds1337_data, list);
 		if (data->client.adapter->nr == bus)
 			return ds1337_command(&data->client, cmd, arg);
 	}

 	return -ENODEV;
 }

 static int ds1337_attach_adapter(struct i2c_adapter *adapter)
 {
 	return i2c_probe(adapter, &addr_data, ds1337_detect);
 }

 /*
  * The following function does more than just detection. If detection
  * succeeds, it also registers the new chip.
  */
 static int ds1337_detect(struct i2c_adapter *adapter, int address, int kind)
 {
 	struct i2c_client *new_client;
 	struct ds1337_data *data;
 	int err = 0;
 	const char *name = "";

 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
 				     I2C_FUNC_I2C))
 		goto exit;

 	if (!(data = kzalloc(sizeof(struct ds1337_data), GFP_KERNEL))) {
 		err = -ENOMEM;
 		goto exit;
 	}
 	INIT_LIST_HEAD(&data->list);

 	/* The common I2C client data is placed right before the
 	 * DS1337-specific data.
 	 */
 	new_client = &data->client;
 	i2c_set_clientdata(new_client, data);
 	new_client->addr = address;
 	new_client->adapter = adapter;
 	new_client->driver = &ds1337_driver;
 	new_client->flags = 0;

 	/*
 	 * Now we do the remaining detection. A negative kind means that
 	 * the driver was loaded with no force parameter (default), so we
 	 * must both detect and identify the chip. A zero kind means that
 	 * the driver was loaded with the force parameter, the detection
 	 * step shall be skipped. A positive kind means that the driver
 	 * was loaded with the force parameter and a given kind of chip is
 	 * requested, so both the detection and the identification steps
 	 * are skipped.
 	 *
 	 * For detection, we read registers that are most likely to cause
 	 * detection failure, i.e. those that have more bits with fixed
 	 * or reserved values.
 	 */

 	/* Default to an DS1337 if forced */
 	if (kind == 0)
 		kind = ds1337;

 	if (kind < 0) {		/* detection and identification */
 		u8 data;

 		/* Check that status register bits 6-2 are zero */
 		if ((ds1337_read(new_client, DS1337_REG_STATUS, &data) < 0) ||
 		    (data & 0x7c))
 			goto exit_free;

 		/* Check for a valid day register value */
 		if ((ds1337_read(new_client, DS1337_REG_DAY, &data) < 0) ||
 		    (data == 0) || (data & 0xf8))
 			goto exit_free;

 		/* Check for a valid date register value */
 		if ((ds1337_read(new_client, DS1337_REG_DATE, &data) < 0) ||
 		    (data == 0) || (data & 0xc0) || ((data & 0x0f) > 9) ||
 		    (data >= 0x32))
 			goto exit_free;

 		/* Check for a valid month register value */
 		if ((ds1337_read(new_client, DS1337_REG_MONTH, &data) < 0) ||
 		    (data == 0) || (data & 0x60) || ((data & 0x0f) > 9) ||
 		    ((data >= 0x13) && (data <= 0x19)))
 			goto exit_free;

 		/* Check that control register bits 6-5 are zero */
 		if ((ds1337_read(new_client, DS1337_REG_CONTROL, &data) < 0) ||
 		    (data & 0x60))
 			goto exit_free;

 		kind = ds1337;
 	}

 	if (kind == ds1337)
 		name = "ds1337";

 	/* We can fill in the remaining client fields */
 	strlcpy(new_client->name, name, I2C_NAME_SIZE);

 	/* Tell the I2C layer a new client has arrived */
 	if ((err = i2c_attach_client(new_client)))
 		goto exit_free;

 	/* Initialize the DS1337 chip */
 	ds1337_init_client(new_client);

 	/* Add client to local list */
 	list_add(&data->list, &ds1337_clients);

 	return 0;

 exit_free:
 	kfree(data);
 exit:
 	return err;
 }

 static void ds1337_init_client(struct i2c_client *client)
 {
 	u8 status, control;

 	/* On some boards, the RTC isn't configured by boot firmware.
 	 * Handle that case by starting/configuring the RTC now.
 	 */
 	status = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
 	control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);

 	if ((status & 0x80) || (control & 0x80)) {
 		/* RTC not running */
 		u8 buf[16];
 		struct i2c_msg msg[1];

 		dev_dbg(&client->dev, "%s: RTC not running!\n", __FUNCTION__);

 		/* Initialize all, including STATUS and CONTROL to zero */
 		memset(buf, 0, sizeof(buf));
 		msg[0].addr = client->addr;
 		msg[0].flags = 0;
 		msg[0].len = sizeof(buf);
 		msg[0].buf = &buf[0];

 		i2c_transfer(client->adapter, msg, 1);
 	} else {
 		/* Running: ensure that device is set in 24-hour mode */
 		s32 val;

 		val = i2c_smbus_read_byte_data(client, DS1337_REG_HOUR);
 		if ((val >= 0) && (val & (1 << 6)))
 			i2c_smbus_write_byte_data(client, DS1337_REG_HOUR,
 						  val & 0x3f);
 	}
 }

 static int ds1337_detach_client(struct i2c_client *client)
 {
 	int err;
 	struct ds1337_data *data = i2c_get_clientdata(client);

 	if ((err = i2c_detach_client(client)))
 		return err;

 	list_del(&data->list);
 	kfree(data);
 	return 0;
 }

 static int __init ds1337_init(void)
 {
 	return i2c_add_driver(&ds1337_driver);
 }

 static void __exit ds1337_exit(void)
 {
 	i2c_del_driver(&ds1337_driver);
 }

 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
 MODULE_DESCRIPTION("DS1337 RTC driver");
 MODULE_LICENSE("GPL");

 EXPORT_SYMBOL_GPL(ds1337_do_command);

 module_init(ds1337_init);
 module_exit(ds1337_exit);
	/*
	* linux/drivers/i2c/chips/ds1337.c
	*
	* Copyright (C) 2005 James Chapman <jchapman@katalix.com>
	*
	* based on linux/drivers/acorn/char/pcf8583.c
	* Copyright (C) 2000 Russell King
	*
	* 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.
	*
	* Driver for Dallas Semiconductor DS1337 and DS1339 real time clock chip
	*/

	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/slab.h>
	#include <linux/i2c.h>
	#include <linux/string.h>
	#include <linux/rtc.h> /* get the user-level API */
	#include <linux/bcd.h>
	#include <linux/list.h>

	/* Device registers */
	#define DS1337_REG_HOUR 2
	#define DS1337_REG_DAY 3
	#define DS1337_REG_DATE 4
	#define DS1337_REG_MONTH 5
	#define DS1337_REG_CONTROL 14
	#define DS1337_REG_STATUS 15

	/* FIXME - how do we export these interface constants? */
	#define DS1337_GET_DATE 0
	#define DS1337_SET_DATE 1

	/*
	* Functions declaration
	*/
	static unsigned short normal_i2c[] = { 0x68, I2C_CLIENT_END };

	I2C_CLIENT_INSMOD_1(ds1337);

	static int ds1337_attach_adapter(struct i2c_adapter *adapter);
	static int ds1337_detect(struct i2c_adapter *adapter, int address, int kind);
	static void ds1337_init_client(struct i2c_client *client);
	static int ds1337_detach_client(struct i2c_client *client);
	static int ds1337_command(struct i2c_client *client, unsigned int cmd,
	void *arg);

	/*
	* Driver data (common to all clients)
	*/
	static struct i2c_driver ds1337_driver = {
	.driver = {
	.name = "ds1337",
	},
	.attach_adapter = ds1337_attach_adapter,
	.detach_client = ds1337_detach_client,
	.command = ds1337_command,
	};

	/*
	* Client data (each client gets its own)
	*/
	struct ds1337_data {
	struct i2c_client client;
	struct list_head list;
	};

	/*
	* Internal variables
	*/
	static LIST_HEAD(ds1337_clients);

	static inline int ds1337_read(struct i2c_client client, u8 reg, u8 value)
	{
	s32 tmp = i2c_smbus_read_byte_data(client, reg);

	if (tmp < 0)
	return -EIO;

	*value = tmp;

	return 0;
	}

	/*
	* Chip access functions
	*/
	static int ds1337_get_datetime(struct i2c_client client, struct rtc_time dt)
	{
	int result;
	u8 buf[7];
	u8 val;
	struct i2c_msg msg[2];
	u8 offs = 0;

	if (!dt) {
	dev_dbg(&client->dev, "%s: EINVAL: dt=NULL\n", __FUNCTION__);
	return -EINVAL;
	}

	msg[0].addr = client->addr;
	msg[0].flags = 0;
	msg[0].len = 1;
	msg[0].buf = &offs;

	msg[1].addr = client->addr;
	msg[1].flags = I2C_M_RD;
	msg[1].len = sizeof(buf);
	msg[1].buf = &buf[0];

	result = i2c_transfer(client->adapter, msg, 2);

	dev_dbg(&client->dev, "%s: [%d] %02x %02x %02x %02x %02x %02x %02x\n",
	__FUNCTION__, result, buf[0], buf[1], buf[2], buf[3],
	buf[4], buf[5], buf[6]);

	if (result == 2) {
	dt->tm_sec = BCD2BIN(buf[0]);
	dt->tm_min = BCD2BIN(buf[1]);
	val = buf[2] & 0x3f;
	dt->tm_hour = BCD2BIN(val);
	dt->tm_wday = BCD2BIN(buf[3]) - 1;
	dt->tm_mday = BCD2BIN(buf[4]);
	val = buf[5] & 0x7f;
	dt->tm_mon = BCD2BIN(val) - 1;
	dt->tm_year = BCD2BIN(buf[6]);
	if (buf[5] & 0x80)
	dt->tm_year += 100;

	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, "
	"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
	__FUNCTION__, dt->tm_sec, dt->tm_min,
	dt->tm_hour, dt->tm_mday,
	dt->tm_mon, dt->tm_year, dt->tm_wday);

	return 0;
	}

	dev_err(&client->dev, "error reading data! %d\n", result);
	return -EIO;
	}

	static int ds1337_set_datetime(struct i2c_client client, struct rtc_time dt)
	{
	int result;
	u8 buf[8];
	u8 val;
	struct i2c_msg msg[1];

	if (!dt) {
	dev_dbg(&client->dev, "%s: EINVAL: dt=NULL\n", __FUNCTION__);
	return -EINVAL;
	}

	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
	"mday=%d, mon=%d, year=%d, wday=%d\n", __FUNCTION__,
	dt->tm_sec, dt->tm_min, dt->tm_hour,
	dt->tm_mday, dt->tm_mon, dt->tm_year, dt->tm_wday);

	buf[0] = 0; /* reg offset */
	buf[1] = BIN2BCD(dt->tm_sec);
	buf[2] = BIN2BCD(dt->tm_min);
	buf[3] = BIN2BCD(dt->tm_hour);
	buf[4] = BIN2BCD(dt->tm_wday + 1);
	buf[5] = BIN2BCD(dt->tm_mday);
	buf[6] = BIN2BCD(dt->tm_mon + 1);
	val = dt->tm_year;
	if (val >= 100) {
	val -= 100;
	buf[6] \|= (1 << 7);
	}
	buf[7] = BIN2BCD(val);

	msg[0].addr = client->addr;
	msg[0].flags = 0;
	msg[0].len = sizeof(buf);
	msg[0].buf = &buf[0];

	result = i2c_transfer(client->adapter, msg, 1);
	if (result == 1)
	return 0;

	dev_err(&client->dev, "error writing data! %d\n", result);
	return -EIO;
	}

	static int ds1337_command(struct i2c_client *client, unsigned int cmd,
	void *arg)
	{
	dev_dbg(&client->dev, "%s: cmd=%d\n", __FUNCTION__, cmd);

	switch (cmd) {
	case DS1337_GET_DATE:
	return ds1337_get_datetime(client, arg);

	case DS1337_SET_DATE:
	return ds1337_set_datetime(client, arg);

	default:
	return -EINVAL;
	}
	}

	/*
	* Public API for access to specific device. Useful for low-level
	* RTC access from kernel code.
	*/
	int ds1337_do_command(int bus, int cmd, void *arg)
	{
	struct list_head *walk;
	struct list_head *tmp;
	struct ds1337_data *data;

	list_for_each_safe(walk, tmp, &ds1337_clients) {
	data = list_entry(walk, struct ds1337_data, list);
	if (data->client.adapter->nr == bus)
	return ds1337_command(&data->client, cmd, arg);
	}

	return -ENODEV;
	}

	static int ds1337_attach_adapter(struct i2c_adapter *adapter)
	{
	return i2c_probe(adapter, &addr_data, ds1337_detect);
	}

	/*
	* The following function does more than just detection. If detection
	* succeeds, it also registers the new chip.
	*/
	static int ds1337_detect(struct i2c_adapter *adapter, int address, int kind)
	{
	struct i2c_client *new_client;
	struct ds1337_data *data;
	int err = 0;
	const char *name = "";

	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA \|
	I2C_FUNC_I2C))
	goto exit;

	if (!(data = kzalloc(sizeof(struct ds1337_data), GFP_KERNEL))) {
	err = -ENOMEM;
	goto exit;
	}
	INIT_LIST_HEAD(&data->list);

	/* The common I2C client data is placed right before the
	* DS1337-specific data.
	*/
	new_client = &data->client;
	i2c_set_clientdata(new_client, data);
	new_client->addr = address;
	new_client->adapter = adapter;
	new_client->driver = &ds1337_driver;
	new_client->flags = 0;

	/*
	* Now we do the remaining detection. A negative kind means that
	* the driver was loaded with no force parameter (default), so we
	* must both detect and identify the chip. A zero kind means that
	* the driver was loaded with the force parameter, the detection
	* step shall be skipped. A positive kind means that the driver
	* was loaded with the force parameter and a given kind of chip is
	* requested, so both the detection and the identification steps
	* are skipped.
	*
	* For detection, we read registers that are most likely to cause
	* detection failure, i.e. those that have more bits with fixed
	* or reserved values.
	*/

	/* Default to an DS1337 if forced */
	if (kind == 0)
	kind = ds1337;

	if (kind < 0) { /* detection and identification */
	u8 data;

	/* Check that status register bits 6-2 are zero */
	if ((ds1337_read(new_client, DS1337_REG_STATUS, &data) < 0) \|\|
	(data & 0x7c))
	goto exit_free;

	/* Check for a valid day register value */
	if ((ds1337_read(new_client, DS1337_REG_DAY, &data) < 0) \|\|
	(data == 0) \|\| (data & 0xf8))
	goto exit_free;

	/* Check for a valid date register value */
	if ((ds1337_read(new_client, DS1337_REG_DATE, &data) < 0) \|\|
	(data == 0) \|\| (data & 0xc0) \|\| ((data & 0x0f) > 9) \|\|
	(data >= 0x32))
	goto exit_free;

	/* Check for a valid month register value */
	if ((ds1337_read(new_client, DS1337_REG_MONTH, &data) < 0) \|\|
	(data == 0) \|\| (data & 0x60) \|\| ((data & 0x0f) > 9) \|\|
	((data >= 0x13) && (data <= 0x19)))
	goto exit_free;

	/* Check that control register bits 6-5 are zero */
	if ((ds1337_read(new_client, DS1337_REG_CONTROL, &data) < 0) \|\|
	(data & 0x60))
	goto exit_free;

	kind = ds1337;
	}

	if (kind == ds1337)
	name = "ds1337";

	/* We can fill in the remaining client fields */
	strlcpy(new_client->name, name, I2C_NAME_SIZE);

	/* Tell the I2C layer a new client has arrived */
	if ((err = i2c_attach_client(new_client)))
	goto exit_free;

	/* Initialize the DS1337 chip */
	ds1337_init_client(new_client);

	/* Add client to local list */
	list_add(&data->list, &ds1337_clients);

	return 0;

	exit_free:
	kfree(data);
	exit:
	return err;
	}

	static void ds1337_init_client(struct i2c_client *client)
	{
	u8 status, control;

	/* On some boards, the RTC isn't configured by boot firmware.
	* Handle that case by starting/configuring the RTC now.
	*/
	status = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
	control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);

	if ((status & 0x80) \|\| (control & 0x80)) {
	/* RTC not running */
	u8 buf[16];
	struct i2c_msg msg[1];

	dev_dbg(&client->dev, "%s: RTC not running!\n", __FUNCTION__);

	/* Initialize all, including STATUS and CONTROL to zero */
	memset(buf, 0, sizeof(buf));
	msg[0].addr = client->addr;
	msg[0].flags = 0;
	msg[0].len = sizeof(buf);
	msg[0].buf = &buf[0];

	i2c_transfer(client->adapter, msg, 1);
	} else {
	/* Running: ensure that device is set in 24-hour mode */
	s32 val;

	val = i2c_smbus_read_byte_data(client, DS1337_REG_HOUR);
	if ((val >= 0) && (val & (1 << 6)))
	i2c_smbus_write_byte_data(client, DS1337_REG_HOUR,
	val & 0x3f);
	}
	}

	static int ds1337_detach_client(struct i2c_client *client)
	{
	int err;
	struct ds1337_data *data = i2c_get_clientdata(client);

	if ((err = i2c_detach_client(client)))
	return err;

	list_del(&data->list);
	kfree(data);
	return 0;
	}

	static int __init ds1337_init(void)
	{
	return i2c_add_driver(&ds1337_driver);
	}

	static void __exit ds1337_exit(void)
	{
	i2c_del_driver(&ds1337_driver);
	}

	MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
	MODULE_DESCRIPTION("DS1337 RTC driver");
	MODULE_LICENSE("GPL");

	EXPORT_SYMBOL_GPL(ds1337_do_command);

	module_init(ds1337_init);
	module_exit(ds1337_exit);