drivers/rtc/rtc-ds1374.c - kernel/msm-4.9 - Gitiles

 /*
  * RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over I2C
  *
  * Based on code by Randy Vinson <rvinson@mvista.com>,
  * which was based on the m41t00.c by Mark Greer <mgreer@mvista.com>.
  *
  * Copyright (C) 2006-2007 Freescale Semiconductor
  *
  * 2005 (c) MontaVista Software, Inc. This file is licensed under
  * the terms of the GNU General Public License version 2. This program
  * is licensed "as is" without any warranty of any kind, whether express
  * or implied.
  */
 /*
  * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
  * recommened in .../Documentation/i2c/writing-clients section
  * "Sending and receiving", using SMBus level communication is preferred.
  */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/interrupt.h>
 #include <linux/i2c.h>
 #include <linux/rtc.h>
 #include <linux/bcd.h>
 #include <linux/workqueue.h>
 #include <linux/slab.h>
 #include <linux/pm.h>

 #define DS1374_REG_TOD0		0x00 /* Time of Day */
 #define DS1374_REG_TOD1		0x01
 #define DS1374_REG_TOD2		0x02
 #define DS1374_REG_TOD3		0x03
 #define DS1374_REG_WDALM0	0x04 /* Watchdog/Alarm */
 #define DS1374_REG_WDALM1	0x05
 #define DS1374_REG_WDALM2	0x06
 #define DS1374_REG_CR		0x07 /* Control */
 #define DS1374_REG_CR_AIE	0x01 /* Alarm Int. Enable */
 #define DS1374_REG_CR_WDALM	0x20 /* 1=Watchdog, 0=Alarm */
 #define DS1374_REG_CR_WACE	0x40 /* WD/Alarm counter enable */
 #define DS1374_REG_SR		0x08 /* Status */
 #define DS1374_REG_SR_OSF	0x80 /* Oscillator Stop Flag */
 #define DS1374_REG_SR_AF	0x01 /* Alarm Flag */
 #define DS1374_REG_TCR		0x09 /* Trickle Charge */

 static const struct i2c_device_id ds1374_id[] = {
 	{ "ds1374", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, ds1374_id);

 struct ds1374 {
 	struct i2c_client *client;
 	struct rtc_device *rtc;
 	struct work_struct work;

 	/* The mutex protects alarm operations, and prevents a race
 	 * between the enable_irq() in the workqueue and the free_irq()
 	 * in the remove function.
 	 */
 	struct mutex mutex;
 	int exiting;
 };

 static struct i2c_driver ds1374_driver;

 static int ds1374_read_rtc(struct i2c_client *client, u32 *time,
                            int reg, int nbytes)
 {
 	u8 buf[4];
 	int ret;
 	int i;

 	if (nbytes > 4) {
 		WARN_ON(1);
 		return -EINVAL;
 	}

 	ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf);

 	if (ret < 0)
 		return ret;
 	if (ret < nbytes)
 		return -EIO;

 	for (i = nbytes - 1, *time = 0; i >= 0; i--)
 		*time = (*time << 8) | buf[i];

 	return 0;
 }

 static int ds1374_write_rtc(struct i2c_client *client, u32 time,
                             int reg, int nbytes)
 {
 	u8 buf[4];
 	int i;

 	if (nbytes > 4) {
 		WARN_ON(1);
 		return -EINVAL;
 	}

 	for (i = 0; i < nbytes; i++) {
 		buf[i] = time & 0xff;
 		time >>= 8;
 	}

 	return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf);
 }

 static int ds1374_check_rtc_status(struct i2c_client *client)
 {
 	int ret = 0;
 	int control, stat;

 	stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 	if (stat < 0)
 		return stat;

 	if (stat & DS1374_REG_SR_OSF)
 		dev_warn(&client->dev,
 		         "oscillator discontinuity flagged, "
 		         "time unreliable\n");

 	stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF);

 	ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
 	if (ret < 0)
 		return ret;

 	/* If the alarm is pending, clear it before requesting
 	 * the interrupt, so an interrupt event isn't reported
 	 * before everything is initialized.
 	 */

 	control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 	if (control < 0)
 		return control;

 	control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
 	return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
 }

 static int ds1374_read_time(struct device *dev, struct rtc_time *time)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	u32 itime;
 	int ret;

 	ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4);
 	if (!ret)
 		rtc_time_to_tm(itime, time);

 	return ret;
 }

 static int ds1374_set_time(struct device *dev, struct rtc_time *time)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	unsigned long itime;

 	rtc_tm_to_time(time, &itime);
 	return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);
 }

 /* The ds1374 has a decrementer for an alarm, rather than a comparator.
  * If the time of day is changed, then the alarm will need to be
  * reset.
  */
 static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct ds1374 *ds1374 = i2c_get_clientdata(client);
 	u32 now, cur_alarm;
 	int cr, sr;
 	int ret = 0;

 	if (client->irq <= 0)
 		return -EINVAL;

 	mutex_lock(&ds1374->mutex);

 	cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 	if (ret < 0)
 		goto out;

 	sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 	if (ret < 0)
 		goto out;

 	ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4);
 	if (ret)
 		goto out;

 	ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3);
 	if (ret)
 		goto out;

 	rtc_time_to_tm(now + cur_alarm, &alarm->time);
 	alarm->enabled = !!(cr & DS1374_REG_CR_WACE);
 	alarm->pending = !!(sr & DS1374_REG_SR_AF);

 out:
 	mutex_unlock(&ds1374->mutex);
 	return ret;
 }

 static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct ds1374 *ds1374 = i2c_get_clientdata(client);
 	struct rtc_time now;
 	unsigned long new_alarm, itime;
 	int cr;
 	int ret = 0;

 	if (client->irq <= 0)
 		return -EINVAL;

 	ret = ds1374_read_time(dev, &now);
 	if (ret < 0)
 		return ret;

 	rtc_tm_to_time(&alarm->time, &new_alarm);
 	rtc_tm_to_time(&now, &itime);

 	/* This can happen due to races, in addition to dates that are
 	 * truly in the past.  To avoid requiring the caller to check for
 	 * races, dates in the past are assumed to be in the recent past
 	 * (i.e. not something that we'd rather the caller know about via
 	 * an error), and the alarm is set to go off as soon as possible.
 	 */
 	if (time_before_eq(new_alarm, itime))
 		new_alarm = 1;
 	else
 		new_alarm -= itime;

 	mutex_lock(&ds1374->mutex);

 	ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 	if (ret < 0)
 		goto out;

 	/* Disable any existing alarm before setting the new one
 	 * (or lack thereof). */
 	cr &= ~DS1374_REG_CR_WACE;

 	ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
 	if (ret < 0)
 		goto out;

 	ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3);
 	if (ret)
 		goto out;

 	if (alarm->enabled) {
 		cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
 		cr &= ~DS1374_REG_CR_WDALM;

 		ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
 	}

 out:
 	mutex_unlock(&ds1374->mutex);
 	return ret;
 }

 static irqreturn_t ds1374_irq(int irq, void *dev_id)
 {
 	struct i2c_client *client = dev_id;
 	struct ds1374 *ds1374 = i2c_get_clientdata(client);

 	disable_irq_nosync(irq);
 	schedule_work(&ds1374->work);
 	return IRQ_HANDLED;
 }

 static void ds1374_work(struct work_struct *work)
 {
 	struct ds1374 *ds1374 = container_of(work, struct ds1374, work);
 	struct i2c_client *client = ds1374->client;
 	int stat, control;

 	mutex_lock(&ds1374->mutex);

 	stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
 	if (stat < 0)
 		goto unlock;

 	if (stat & DS1374_REG_SR_AF) {
 		stat &= ~DS1374_REG_SR_AF;
 		i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);

 		control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 		if (control < 0)
 			goto out;

 		control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
 		i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);

 		rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF);
 	}

 out:
 	if (!ds1374->exiting)
 		enable_irq(client->irq);
 unlock:
 	mutex_unlock(&ds1374->mutex);
 }

 static int ds1374_alarm_irq_enable(struct device *dev, unsigned int enabled)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct ds1374 *ds1374 = i2c_get_clientdata(client);
 	int ret;

 	mutex_lock(&ds1374->mutex);

 	ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
 	if (ret < 0)
 		goto out;

 	if (enabled) {
 		ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
 		ret &= ~DS1374_REG_CR_WDALM;
 	} else {
 		ret &= ~DS1374_REG_CR_WACE;
 	}
 	ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);

 out:
 	mutex_unlock(&ds1374->mutex);
 	return ret;
 }

 static const struct rtc_class_ops ds1374_rtc_ops = {
 	.read_time = ds1374_read_time,
 	.set_time = ds1374_set_time,
 	.read_alarm = ds1374_read_alarm,
 	.set_alarm = ds1374_set_alarm,
 	.alarm_irq_enable = ds1374_alarm_irq_enable,
 };

 static int ds1374_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
 	struct ds1374 *ds1374;
 	int ret;

 	ds1374 = kzalloc(sizeof(struct ds1374), GFP_KERNEL);
 	if (!ds1374)
 		return -ENOMEM;

 	ds1374->client = client;
 	i2c_set_clientdata(client, ds1374);

 	INIT_WORK(&ds1374->work, ds1374_work);
 	mutex_init(&ds1374->mutex);

 	ret = ds1374_check_rtc_status(client);
 	if (ret)
 		goto out_free;

 	if (client->irq > 0) {
 		ret = request_irq(client->irq, ds1374_irq, 0,
 		                  "ds1374", client);
 		if (ret) {
 			dev_err(&client->dev, "unable to request IRQ\n");
 			goto out_free;
 		}

 		device_set_wakeup_capable(&client->dev, 1);
 	}

 	ds1374->rtc = rtc_device_register(client->name, &client->dev,
 	                                  &ds1374_rtc_ops, THIS_MODULE);
 	if (IS_ERR(ds1374->rtc)) {
 		ret = PTR_ERR(ds1374->rtc);
 		dev_err(&client->dev, "unable to register the class device\n");
 		goto out_irq;
 	}

 	return 0;

 out_irq:
 	if (client->irq > 0)
 		free_irq(client->irq, client);

 out_free:
 	kfree(ds1374);
 	return ret;
 }

 static int __devexit ds1374_remove(struct i2c_client *client)
 {
 	struct ds1374 *ds1374 = i2c_get_clientdata(client);

 	if (client->irq > 0) {
 		mutex_lock(&ds1374->mutex);
 		ds1374->exiting = 1;
 		mutex_unlock(&ds1374->mutex);

 		free_irq(client->irq, client);
 		cancel_work_sync(&ds1374->work);
 	}

 	rtc_device_unregister(ds1374->rtc);
 	kfree(ds1374);
 	return 0;
 }

 #ifdef CONFIG_PM
 static int ds1374_suspend(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);

 	if (client->irq >= 0 && device_may_wakeup(&client->dev))
 		enable_irq_wake(client->irq);
 	return 0;
 }

 static int ds1374_resume(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);

 	if (client->irq >= 0 && device_may_wakeup(&client->dev))
 		disable_irq_wake(client->irq);
 	return 0;
 }

 static SIMPLE_DEV_PM_OPS(ds1374_pm, ds1374_suspend, ds1374_resume);

 #define DS1374_PM (&ds1374_pm)
 #else
 #define DS1374_PM NULL
 #endif

 static struct i2c_driver ds1374_driver = {
 	.driver = {
 		.name = "rtc-ds1374",
 		.owner = THIS_MODULE,
 		.pm = DS1374_PM,
 	},
 	.probe = ds1374_probe,
 	.remove = __devexit_p(ds1374_remove),
 	.id_table = ds1374_id,
 };

 module_i2c_driver(ds1374_driver);

 MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>");
 MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");
 MODULE_LICENSE("GPL");
	/*
	* RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over I2C
	*
	* Based on code by Randy Vinson <rvinson@mvista.com>,
	* which was based on the m41t00.c by Mark Greer <mgreer@mvista.com>.
	*
	* Copyright (C) 2006-2007 Freescale Semiconductor
	*
	* 2005 (c) MontaVista Software, Inc. This file is licensed under
	* the terms of the GNU General Public License version 2. This program
	* is licensed "as is" without any warranty of any kind, whether express
	* or implied.
	*/
	/*
	* It would be more efficient to use i2c msgs/i2c_transfer directly but, as
	* recommened in .../Documentation/i2c/writing-clients section
	* "Sending and receiving", using SMBus level communication is preferred.
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/interrupt.h>
	#include <linux/i2c.h>
	#include <linux/rtc.h>
	#include <linux/bcd.h>
	#include <linux/workqueue.h>
	#include <linux/slab.h>
	#include <linux/pm.h>

	#define DS1374_REG_TOD0 0x00 /* Time of Day */
	#define DS1374_REG_TOD1 0x01
	#define DS1374_REG_TOD2 0x02
	#define DS1374_REG_TOD3 0x03
	#define DS1374_REG_WDALM0 0x04 /* Watchdog/Alarm */
	#define DS1374_REG_WDALM1 0x05
	#define DS1374_REG_WDALM2 0x06
	#define DS1374_REG_CR 0x07 /* Control */
	#define DS1374_REG_CR_AIE 0x01 /* Alarm Int. Enable */
	#define DS1374_REG_CR_WDALM 0x20 /* 1=Watchdog, 0=Alarm */
	#define DS1374_REG_CR_WACE 0x40 /* WD/Alarm counter enable */
	#define DS1374_REG_SR 0x08 /* Status */
	#define DS1374_REG_SR_OSF 0x80 /* Oscillator Stop Flag */
	#define DS1374_REG_SR_AF 0x01 /* Alarm Flag */
	#define DS1374_REG_TCR 0x09 /* Trickle Charge */

	static const struct i2c_device_id ds1374_id[] = {
	{ "ds1374", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, ds1374_id);

	struct ds1374 {
	struct i2c_client *client;
	struct rtc_device *rtc;
	struct work_struct work;

	/* The mutex protects alarm operations, and prevents a race
	* between the enable_irq() in the workqueue and the free_irq()
	* in the remove function.
	*/
	struct mutex mutex;
	int exiting;
	};

	static struct i2c_driver ds1374_driver;

	static int ds1374_read_rtc(struct i2c_client client, u32 time,
	int reg, int nbytes)
	{
	u8 buf[4];
	int ret;
	int i;

	if (nbytes > 4) {
	WARN_ON(1);
	return -EINVAL;
	}

	ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf);

	if (ret < 0)
	return ret;
	if (ret < nbytes)
	return -EIO;

	for (i = nbytes - 1, *time = 0; i >= 0; i--)
	time = (time << 8) \| buf[i];

	return 0;
	}

	static int ds1374_write_rtc(struct i2c_client *client, u32 time,
	int reg, int nbytes)
	{
	u8 buf[4];
	int i;

	if (nbytes > 4) {
	WARN_ON(1);
	return -EINVAL;
	}

	for (i = 0; i < nbytes; i++) {
	buf[i] = time & 0xff;
	time >>= 8;
	}

	return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf);
	}

	static int ds1374_check_rtc_status(struct i2c_client *client)
	{
	int ret = 0;
	int control, stat;

	stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
	if (stat < 0)
	return stat;

	if (stat & DS1374_REG_SR_OSF)
	dev_warn(&client->dev,
	"oscillator discontinuity flagged, "
	"time unreliable\n");

	stat &= ~(DS1374_REG_SR_OSF \| DS1374_REG_SR_AF);

	ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
	if (ret < 0)
	return ret;

	/* If the alarm is pending, clear it before requesting
	* the interrupt, so an interrupt event isn't reported
	* before everything is initialized.
	*/

	control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
	if (control < 0)
	return control;

	control &= ~(DS1374_REG_CR_WACE \| DS1374_REG_CR_AIE);
	return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
	}

	static int ds1374_read_time(struct device dev, struct rtc_time time)
	{
	struct i2c_client *client = to_i2c_client(dev);
	u32 itime;
	int ret;

	ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4);
	if (!ret)
	rtc_time_to_tm(itime, time);

	return ret;
	}

	static int ds1374_set_time(struct device dev, struct rtc_time time)
	{
	struct i2c_client *client = to_i2c_client(dev);
	unsigned long itime;

	rtc_tm_to_time(time, &itime);
	return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);
	}

	/* The ds1374 has a decrementer for an alarm, rather than a comparator.
	* If the time of day is changed, then the alarm will need to be
	* reset.
	*/
	static int ds1374_read_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct ds1374 *ds1374 = i2c_get_clientdata(client);
	u32 now, cur_alarm;
	int cr, sr;
	int ret = 0;

	if (client->irq <= 0)
	return -EINVAL;

	mutex_lock(&ds1374->mutex);

	cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
	if (ret < 0)
	goto out;

	sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
	if (ret < 0)
	goto out;

	ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4);
	if (ret)
	goto out;

	ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3);
	if (ret)
	goto out;

	rtc_time_to_tm(now + cur_alarm, &alarm->time);
	alarm->enabled = !!(cr & DS1374_REG_CR_WACE);
	alarm->pending = !!(sr & DS1374_REG_SR_AF);

	out:
	mutex_unlock(&ds1374->mutex);
	return ret;
	}

	static int ds1374_set_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct ds1374 *ds1374 = i2c_get_clientdata(client);
	struct rtc_time now;
	unsigned long new_alarm, itime;
	int cr;
	int ret = 0;

	if (client->irq <= 0)
	return -EINVAL;

	ret = ds1374_read_time(dev, &now);
	if (ret < 0)
	return ret;

	rtc_tm_to_time(&alarm->time, &new_alarm);
	rtc_tm_to_time(&now, &itime);

	/* This can happen due to races, in addition to dates that are
	* truly in the past. To avoid requiring the caller to check for
	* races, dates in the past are assumed to be in the recent past
	* (i.e. not something that we'd rather the caller know about via
	* an error), and the alarm is set to go off as soon as possible.
	*/
	if (time_before_eq(new_alarm, itime))
	new_alarm = 1;
	else
	new_alarm -= itime;

	mutex_lock(&ds1374->mutex);

	ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
	if (ret < 0)
	goto out;

	/* Disable any existing alarm before setting the new one
	* (or lack thereof). */
	cr &= ~DS1374_REG_CR_WACE;

	ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
	if (ret < 0)
	goto out;

	ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3);
	if (ret)
	goto out;

	if (alarm->enabled) {
	cr \|= DS1374_REG_CR_WACE \| DS1374_REG_CR_AIE;
	cr &= ~DS1374_REG_CR_WDALM;

	ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
	}

	out:
	mutex_unlock(&ds1374->mutex);
	return ret;
	}

	static irqreturn_t ds1374_irq(int irq, void *dev_id)
	{
	struct i2c_client *client = dev_id;
	struct ds1374 *ds1374 = i2c_get_clientdata(client);

	disable_irq_nosync(irq);
	schedule_work(&ds1374->work);
	return IRQ_HANDLED;
	}

	static void ds1374_work(struct work_struct *work)
	{
	struct ds1374 *ds1374 = container_of(work, struct ds1374, work);
	struct i2c_client *client = ds1374->client;
	int stat, control;

	mutex_lock(&ds1374->mutex);

	stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
	if (stat < 0)
	goto unlock;

	if (stat & DS1374_REG_SR_AF) {
	stat &= ~DS1374_REG_SR_AF;
	i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);

	control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
	if (control < 0)
	goto out;

	control &= ~(DS1374_REG_CR_WACE \| DS1374_REG_CR_AIE);
	i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);

	rtc_update_irq(ds1374->rtc, 1, RTC_AF \| RTC_IRQF);
	}

	out:
	if (!ds1374->exiting)
	enable_irq(client->irq);
	unlock:
	mutex_unlock(&ds1374->mutex);
	}

	static int ds1374_alarm_irq_enable(struct device *dev, unsigned int enabled)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct ds1374 *ds1374 = i2c_get_clientdata(client);
	int ret;

	mutex_lock(&ds1374->mutex);

	ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
	if (ret < 0)
	goto out;

	if (enabled) {
	ret \|= DS1374_REG_CR_WACE \| DS1374_REG_CR_AIE;
	ret &= ~DS1374_REG_CR_WDALM;
	} else {
	ret &= ~DS1374_REG_CR_WACE;
	}
	ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);

	out:
	mutex_unlock(&ds1374->mutex);
	return ret;
	}

	static const struct rtc_class_ops ds1374_rtc_ops = {
	.read_time = ds1374_read_time,
	.set_time = ds1374_set_time,
	.read_alarm = ds1374_read_alarm,
	.set_alarm = ds1374_set_alarm,
	.alarm_irq_enable = ds1374_alarm_irq_enable,
	};

	static int ds1374_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct ds1374 *ds1374;
	int ret;

	ds1374 = kzalloc(sizeof(struct ds1374), GFP_KERNEL);
	if (!ds1374)
	return -ENOMEM;

	ds1374->client = client;
	i2c_set_clientdata(client, ds1374);

	INIT_WORK(&ds1374->work, ds1374_work);
	mutex_init(&ds1374->mutex);

	ret = ds1374_check_rtc_status(client);
	if (ret)
	goto out_free;

	if (client->irq > 0) {
	ret = request_irq(client->irq, ds1374_irq, 0,
	"ds1374", client);
	if (ret) {
	dev_err(&client->dev, "unable to request IRQ\n");
	goto out_free;
	}

	device_set_wakeup_capable(&client->dev, 1);
	}

	ds1374->rtc = rtc_device_register(client->name, &client->dev,
	&ds1374_rtc_ops, THIS_MODULE);
	if (IS_ERR(ds1374->rtc)) {
	ret = PTR_ERR(ds1374->rtc);
	dev_err(&client->dev, "unable to register the class device\n");
	goto out_irq;
	}

	return 0;

	out_irq:
	if (client->irq > 0)
	free_irq(client->irq, client);

	out_free:
	kfree(ds1374);
	return ret;
	}

	static int __devexit ds1374_remove(struct i2c_client *client)
	{
	struct ds1374 *ds1374 = i2c_get_clientdata(client);

	if (client->irq > 0) {
	mutex_lock(&ds1374->mutex);
	ds1374->exiting = 1;
	mutex_unlock(&ds1374->mutex);

	free_irq(client->irq, client);
	cancel_work_sync(&ds1374->work);
	}

	rtc_device_unregister(ds1374->rtc);
	kfree(ds1374);
	return 0;
	}

	#ifdef CONFIG_PM
	static int ds1374_suspend(struct device *dev)
	{
	struct i2c_client *client = to_i2c_client(dev);

	if (client->irq >= 0 && device_may_wakeup(&client->dev))
	enable_irq_wake(client->irq);
	return 0;
	}

	static int ds1374_resume(struct device *dev)
	{
	struct i2c_client *client = to_i2c_client(dev);

	if (client->irq >= 0 && device_may_wakeup(&client->dev))
	disable_irq_wake(client->irq);
	return 0;
	}

	static SIMPLE_DEV_PM_OPS(ds1374_pm, ds1374_suspend, ds1374_resume);

	#define DS1374_PM (&ds1374_pm)
	#else
	#define DS1374_PM NULL
	#endif

	static struct i2c_driver ds1374_driver = {
	.driver = {
	.name = "rtc-ds1374",
	.owner = THIS_MODULE,
	.pm = DS1374_PM,
	},
	.probe = ds1374_probe,
	.remove = __devexit_p(ds1374_remove),
	.id_table = ds1374_id,
	};

	module_i2c_driver(ds1374_driver);

	MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>");
	MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");
	MODULE_LICENSE("GPL");