drivers/rtc/rtc-ds3232.c - kernel/msm-4.9 - Gitiles

 /*
  * RTC client/driver for the Maxim/Dallas DS3232 Real-Time Clock over I2C
  *
  * Copyright (C) 2009-2010 Freescale Semiconductor.
  * Author: Jack Lan <jack.lan@freescale.com>
  *
  * This program is free software; you can redistribute  it and/or modify it
  * under  the terms of  the GNU General  Public License as published by the
  * Free Software Foundation;  either version 2 of the  License, or (at your
  * option) any later version.
  */
 /*
  * 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>

 #define DS3232_REG_SECONDS	0x00
 #define DS3232_REG_MINUTES	0x01
 #define DS3232_REG_HOURS	0x02
 #define DS3232_REG_AMPM		0x02
 #define DS3232_REG_DAY		0x03
 #define DS3232_REG_DATE		0x04
 #define DS3232_REG_MONTH	0x05
 #define DS3232_REG_CENTURY	0x05
 #define DS3232_REG_YEAR		0x06
 #define DS3232_REG_ALARM1         0x07	/* Alarm 1 BASE */
 #define DS3232_REG_ALARM2         0x0B	/* Alarm 2 BASE */
 #define DS3232_REG_CR		0x0E	/* Control register */
 #	define DS3232_REG_CR_nEOSC        0x80
 #       define DS3232_REG_CR_INTCN        0x04
 #       define DS3232_REG_CR_A2IE        0x02
 #       define DS3232_REG_CR_A1IE        0x01

 #define DS3232_REG_SR	0x0F	/* control/status register */
 #	define DS3232_REG_SR_OSF   0x80
 #       define DS3232_REG_SR_BSY   0x04
 #       define DS3232_REG_SR_A2F   0x02
 #       define DS3232_REG_SR_A1F   0x01

 struct ds3232 {
 	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 ds3232_driver;

 static int ds3232_check_rtc_status(struct i2c_client *client)
 {
 	int ret = 0;
 	int control, stat;

 	stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
 	if (stat < 0)
 		return stat;

 	if (stat & DS3232_REG_SR_OSF)
 		dev_warn(&client->dev,
 				"oscillator discontinuity flagged, "
 				"time unreliable\n");

 	stat &= ~(DS3232_REG_SR_OSF | DS3232_REG_SR_A1F | DS3232_REG_SR_A2F);

 	ret = i2c_smbus_write_byte_data(client, DS3232_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, DS3232_REG_CR);
 	if (control < 0)
 		return control;

 	control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE);
 	control |= DS3232_REG_CR_INTCN;

 	return i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
 }

 static int ds3232_read_time(struct device *dev, struct rtc_time *time)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	int ret;
 	u8 buf[7];
 	unsigned int year, month, day, hour, minute, second;
 	unsigned int week, twelve_hr, am_pm;
 	unsigned int century, add_century = 0;

 	ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_SECONDS, 7, buf);

 	if (ret < 0)
 		return ret;
 	if (ret < 7)
 		return -EIO;

 	second = buf[0];
 	minute = buf[1];
 	hour = buf[2];
 	week = buf[3];
 	day = buf[4];
 	month = buf[5];
 	year = buf[6];

 	/* Extract additional information for AM/PM and century */

 	twelve_hr = hour & 0x40;
 	am_pm = hour & 0x20;
 	century = month & 0x80;

 	/* Write to rtc_time structure */

 	time->tm_sec = bcd2bin(second);
 	time->tm_min = bcd2bin(minute);
 	if (twelve_hr) {
 		/* Convert to 24 hr */
 		if (am_pm)
 			time->tm_hour = bcd2bin(hour & 0x1F) + 12;
 		else
 			time->tm_hour = bcd2bin(hour & 0x1F);
 	} else {
 		time->tm_hour = bcd2bin(hour);
 	}

 	time->tm_wday = bcd2bin(week);
 	time->tm_mday = bcd2bin(day);
 	time->tm_mon = bcd2bin(month & 0x7F);
 	if (century)
 		add_century = 100;

 	time->tm_year = bcd2bin(year) + add_century;

 	return rtc_valid_tm(time);
 }

 static int ds3232_set_time(struct device *dev, struct rtc_time *time)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	u8 buf[7];

 	/* Extract time from rtc_time and load into ds3232*/

 	buf[0] = bin2bcd(time->tm_sec);
 	buf[1] = bin2bcd(time->tm_min);
 	buf[2] = bin2bcd(time->tm_hour);
 	buf[3] = bin2bcd(time->tm_wday); /* Day of the week */
 	buf[4] = bin2bcd(time->tm_mday); /* Date */
 	buf[5] = bin2bcd(time->tm_mon);
 	if (time->tm_year >= 100) {
 		buf[5] |= 0x80;
 		buf[6] = bin2bcd(time->tm_year - 100);
 	} else {
 		buf[6] = bin2bcd(time->tm_year);
 	}

 	return i2c_smbus_write_i2c_block_data(client,
 					      DS3232_REG_SECONDS, 7, buf);
 }

 /*
  * DS3232 has two alarm, we only use alarm1
  * According to linux specification, only support one-shot alarm
  * no periodic alarm mode
  */
 static int ds3232_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct ds3232 *ds3232 = i2c_get_clientdata(client);
 	int control, stat;
 	int ret;
 	u8 buf[4];

 	mutex_lock(&ds3232->mutex);

 	ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
 	if (ret < 0)
 		goto out;
 	stat = ret;
 	ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
 	if (ret < 0)
 		goto out;
 	control = ret;
 	ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
 	if (ret < 0)
 		goto out;

 	alarm->time.tm_sec = bcd2bin(buf[0] & 0x7F);
 	alarm->time.tm_min = bcd2bin(buf[1] & 0x7F);
 	alarm->time.tm_hour = bcd2bin(buf[2] & 0x7F);
 	alarm->time.tm_mday = bcd2bin(buf[3] & 0x7F);

 	alarm->time.tm_mon = -1;
 	alarm->time.tm_year = -1;
 	alarm->time.tm_wday = -1;
 	alarm->time.tm_yday = -1;
 	alarm->time.tm_isdst = -1;

 	alarm->enabled = !!(control & DS3232_REG_CR_A1IE);
 	alarm->pending = !!(stat & DS3232_REG_SR_A1F);

 	ret = 0;
 out:
 	mutex_unlock(&ds3232->mutex);
 	return ret;
 }

 /*
  * linux rtc-module does not support wday alarm
  * and only 24h time mode supported indeed
  */
 static int ds3232_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct ds3232 *ds3232 = i2c_get_clientdata(client);
 	int control, stat;
 	int ret;
 	u8 buf[4];

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

 	mutex_lock(&ds3232->mutex);

 	buf[0] = bin2bcd(alarm->time.tm_sec);
 	buf[1] = bin2bcd(alarm->time.tm_min);
 	buf[2] = bin2bcd(alarm->time.tm_hour);
 	buf[3] = bin2bcd(alarm->time.tm_mday);

 	/* clear alarm interrupt enable bit */
 	ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
 	if (ret < 0)
 		goto out;
 	control = ret;
 	control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE);
 	ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
 	if (ret < 0)
 		goto out;

 	/* clear any pending alarm flag */
 	ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
 	if (ret < 0)
 		goto out;
 	stat = ret;
 	stat &= ~(DS3232_REG_SR_A1F | DS3232_REG_SR_A2F);
 	ret = i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);
 	if (ret < 0)
 		goto out;

 	ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);

 	if (alarm->enabled) {
 		control |= DS3232_REG_CR_A1IE;
 		ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
 	}
 out:
 	mutex_unlock(&ds3232->mutex);
 	return ret;
 }

 static void ds3232_update_alarm(struct i2c_client *client)
 {
 	struct ds3232 *ds3232 = i2c_get_clientdata(client);
 	int control;
 	int ret;
 	u8 buf[4];

 	mutex_lock(&ds3232->mutex);

 	ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
 	if (ret < 0)
 		goto unlock;

 	buf[0] = bcd2bin(buf[0]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
 								0x80 : buf[0];
 	buf[1] = bcd2bin(buf[1]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
 								0x80 : buf[1];
 	buf[2] = bcd2bin(buf[2]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
 								0x80 : buf[2];
 	buf[3] = bcd2bin(buf[3]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
 								0x80 : buf[3];

 	ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
 	if (ret < 0)
 		goto unlock;

 	control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
 	if (control < 0)
 		goto unlock;

 	if (ds3232->rtc->irq_data & (RTC_AF | RTC_UF))
 		/* enable alarm1 interrupt */
 		control |= DS3232_REG_CR_A1IE;
 	else
 		/* disable alarm1 interrupt */
 		control &= ~(DS3232_REG_CR_A1IE);
 	i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);

 unlock:
 	mutex_unlock(&ds3232->mutex);
 }

 static int ds3232_alarm_irq_enable(struct device *dev, unsigned int enabled)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct ds3232 *ds3232 = i2c_get_clientdata(client);

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

 	if (enabled)
 		ds3232->rtc->irq_data |= RTC_AF;
 	else
 		ds3232->rtc->irq_data &= ~RTC_AF;

 	ds3232_update_alarm(client);
 	return 0;
 }

 static int ds3232_update_irq_enable(struct device *dev, unsigned int enabled)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct ds3232 *ds3232 = i2c_get_clientdata(client);

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

 	if (enabled)
 		ds3232->rtc->irq_data |= RTC_UF;
 	else
 		ds3232->rtc->irq_data &= ~RTC_UF;

 	ds3232_update_alarm(client);
 	return 0;
 }

 static irqreturn_t ds3232_irq(int irq, void *dev_id)
 {
 	struct i2c_client *client = dev_id;
 	struct ds3232 *ds3232 = i2c_get_clientdata(client);

 	disable_irq_nosync(irq);
 	schedule_work(&ds3232->work);
 	return IRQ_HANDLED;
 }

 static void ds3232_work(struct work_struct *work)
 {
 	struct ds3232 *ds3232 = container_of(work, struct ds3232, work);
 	struct i2c_client *client = ds3232->client;
 	int stat, control;

 	mutex_lock(&ds3232->mutex);

 	stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
 	if (stat < 0)
 		goto unlock;

 	if (stat & DS3232_REG_SR_A1F) {
 		control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
 		if (control < 0)
 			goto out;
 		/* disable alarm1 interrupt */
 		control &= ~(DS3232_REG_CR_A1IE);
 		i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);

 		/* clear the alarm pend flag */
 		stat &= ~DS3232_REG_SR_A1F;
 		i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);

 		rtc_update_irq(ds3232->rtc, 1, RTC_AF | RTC_IRQF);
 	}

 out:
 	if (!ds3232->exiting)
 		enable_irq(client->irq);
 unlock:
 	mutex_unlock(&ds3232->mutex);
 }

 static const struct rtc_class_ops ds3232_rtc_ops = {
 	.read_time = ds3232_read_time,
 	.set_time = ds3232_set_time,
 	.read_alarm = ds3232_read_alarm,
 	.set_alarm = ds3232_set_alarm,
 	.alarm_irq_enable = ds3232_alarm_irq_enable,
 	.update_irq_enable = ds3232_update_irq_enable,
 };

 static int __devinit ds3232_probe(struct i2c_client *client,
 		const struct i2c_device_id *id)
 {
 	struct ds3232 *ds3232;
 	int ret;

 	ds3232 = kzalloc(sizeof(struct ds3232), GFP_KERNEL);
 	if (!ds3232)
 		return -ENOMEM;

 	ds3232->client = client;
 	i2c_set_clientdata(client, ds3232);

 	INIT_WORK(&ds3232->work, ds3232_work);
 	mutex_init(&ds3232->mutex);

 	ret = ds3232_check_rtc_status(client);
 	if (ret)
 		goto out_free;

 	ds3232->rtc = rtc_device_register(client->name, &client->dev,
 					  &ds3232_rtc_ops, THIS_MODULE);
 	if (IS_ERR(ds3232->rtc)) {
 		ret = PTR_ERR(ds3232->rtc);
 		dev_err(&client->dev, "unable to register the class device\n");
 		goto out_irq;
 	}

 	if (client->irq >= 0) {
 		ret = request_irq(client->irq, ds3232_irq, 0,
 				 "ds3232", client);
 		if (ret) {
 			dev_err(&client->dev, "unable to request IRQ\n");
 			goto out_free;
 		}
 	}

 	return 0;

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

 out_free:
 	kfree(ds3232);
 	return ret;
 }

 static int __devexit ds3232_remove(struct i2c_client *client)
 {
 	struct ds3232 *ds3232 = i2c_get_clientdata(client);

 	if (client->irq >= 0) {
 		mutex_lock(&ds3232->mutex);
 		ds3232->exiting = 1;
 		mutex_unlock(&ds3232->mutex);

 		free_irq(client->irq, client);
 		flush_scheduled_work();
 	}

 	rtc_device_unregister(ds3232->rtc);
 	kfree(ds3232);
 	return 0;
 }

 static const struct i2c_device_id ds3232_id[] = {
 	{ "ds3232", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, ds3232_id);

 static struct i2c_driver ds3232_driver = {
 	.driver = {
 		.name = "rtc-ds3232",
 		.owner = THIS_MODULE,
 	},
 	.probe = ds3232_probe,
 	.remove = __devexit_p(ds3232_remove),
 	.id_table = ds3232_id,
 };

 static int __init ds3232_init(void)
 {
 	return i2c_add_driver(&ds3232_driver);
 }

 static void __exit ds3232_exit(void)
 {
 	i2c_del_driver(&ds3232_driver);
 }

 module_init(ds3232_init);
 module_exit(ds3232_exit);

 MODULE_AUTHOR("Srikanth Srinivasan <srikanth.srinivasan@freescale.com>");
 MODULE_DESCRIPTION("Maxim/Dallas DS3232 RTC Driver");
 MODULE_LICENSE("GPL");
	/*
	* RTC client/driver for the Maxim/Dallas DS3232 Real-Time Clock over I2C
	*
	* Copyright (C) 2009-2010 Freescale Semiconductor.
	* Author: Jack Lan <jack.lan@freescale.com>
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License as published by the
	* Free Software Foundation; either version 2 of the License, or (at your
	* option) any later version.
	*/
	/*
	* 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>

	#define DS3232_REG_SECONDS 0x00
	#define DS3232_REG_MINUTES 0x01
	#define DS3232_REG_HOURS 0x02
	#define DS3232_REG_AMPM 0x02
	#define DS3232_REG_DAY 0x03
	#define DS3232_REG_DATE 0x04
	#define DS3232_REG_MONTH 0x05
	#define DS3232_REG_CENTURY 0x05
	#define DS3232_REG_YEAR 0x06
	#define DS3232_REG_ALARM1 0x07 /* Alarm 1 BASE */
	#define DS3232_REG_ALARM2 0x0B /* Alarm 2 BASE */
	#define DS3232_REG_CR 0x0E /* Control register */
	# define DS3232_REG_CR_nEOSC 0x80
	# define DS3232_REG_CR_INTCN 0x04
	# define DS3232_REG_CR_A2IE 0x02
	# define DS3232_REG_CR_A1IE 0x01

	#define DS3232_REG_SR 0x0F /* control/status register */
	# define DS3232_REG_SR_OSF 0x80
	# define DS3232_REG_SR_BSY 0x04
	# define DS3232_REG_SR_A2F 0x02
	# define DS3232_REG_SR_A1F 0x01

	struct ds3232 {
	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 ds3232_driver;

	static int ds3232_check_rtc_status(struct i2c_client *client)
	{
	int ret = 0;
	int control, stat;

	stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
	if (stat < 0)
	return stat;

	if (stat & DS3232_REG_SR_OSF)
	dev_warn(&client->dev,
	"oscillator discontinuity flagged, "
	"time unreliable\n");

	stat &= ~(DS3232_REG_SR_OSF \| DS3232_REG_SR_A1F \| DS3232_REG_SR_A2F);

	ret = i2c_smbus_write_byte_data(client, DS3232_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, DS3232_REG_CR);
	if (control < 0)
	return control;

	control &= ~(DS3232_REG_CR_A1IE \| DS3232_REG_CR_A2IE);
	control \|= DS3232_REG_CR_INTCN;

	return i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
	}

	static int ds3232_read_time(struct device dev, struct rtc_time time)
	{
	struct i2c_client *client = to_i2c_client(dev);
	int ret;
	u8 buf[7];
	unsigned int year, month, day, hour, minute, second;
	unsigned int week, twelve_hr, am_pm;
	unsigned int century, add_century = 0;

	ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_SECONDS, 7, buf);

	if (ret < 0)
	return ret;
	if (ret < 7)
	return -EIO;

	second = buf[0];
	minute = buf[1];
	hour = buf[2];
	week = buf[3];
	day = buf[4];
	month = buf[5];
	year = buf[6];

	/* Extract additional information for AM/PM and century */

	twelve_hr = hour & 0x40;
	am_pm = hour & 0x20;
	century = month & 0x80;

	/* Write to rtc_time structure */

	time->tm_sec = bcd2bin(second);
	time->tm_min = bcd2bin(minute);
	if (twelve_hr) {
	/* Convert to 24 hr */
	if (am_pm)
	time->tm_hour = bcd2bin(hour & 0x1F) + 12;
	else
	time->tm_hour = bcd2bin(hour & 0x1F);
	} else {
	time->tm_hour = bcd2bin(hour);
	}

	time->tm_wday = bcd2bin(week);
	time->tm_mday = bcd2bin(day);
	time->tm_mon = bcd2bin(month & 0x7F);
	if (century)
	add_century = 100;

	time->tm_year = bcd2bin(year) + add_century;

	return rtc_valid_tm(time);
	}

	static int ds3232_set_time(struct device dev, struct rtc_time time)
	{
	struct i2c_client *client = to_i2c_client(dev);
	u8 buf[7];

	/* Extract time from rtc_time and load into ds3232*/

	buf[0] = bin2bcd(time->tm_sec);
	buf[1] = bin2bcd(time->tm_min);
	buf[2] = bin2bcd(time->tm_hour);
	buf[3] = bin2bcd(time->tm_wday); /* Day of the week */
	buf[4] = bin2bcd(time->tm_mday); /* Date */
	buf[5] = bin2bcd(time->tm_mon);
	if (time->tm_year >= 100) {
	buf[5] \|= 0x80;
	buf[6] = bin2bcd(time->tm_year - 100);
	} else {
	buf[6] = bin2bcd(time->tm_year);
	}

	return i2c_smbus_write_i2c_block_data(client,
	DS3232_REG_SECONDS, 7, buf);
	}

	/*
	* DS3232 has two alarm, we only use alarm1
	* According to linux specification, only support one-shot alarm
	* no periodic alarm mode
	*/
	static int ds3232_read_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct ds3232 *ds3232 = i2c_get_clientdata(client);
	int control, stat;
	int ret;
	u8 buf[4];

	mutex_lock(&ds3232->mutex);

	ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
	if (ret < 0)
	goto out;
	stat = ret;
	ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
	if (ret < 0)
	goto out;
	control = ret;
	ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
	if (ret < 0)
	goto out;

	alarm->time.tm_sec = bcd2bin(buf[0] & 0x7F);
	alarm->time.tm_min = bcd2bin(buf[1] & 0x7F);
	alarm->time.tm_hour = bcd2bin(buf[2] & 0x7F);
	alarm->time.tm_mday = bcd2bin(buf[3] & 0x7F);

	alarm->time.tm_mon = -1;
	alarm->time.tm_year = -1;
	alarm->time.tm_wday = -1;
	alarm->time.tm_yday = -1;
	alarm->time.tm_isdst = -1;

	alarm->enabled = !!(control & DS3232_REG_CR_A1IE);
	alarm->pending = !!(stat & DS3232_REG_SR_A1F);

	ret = 0;
	out:
	mutex_unlock(&ds3232->mutex);
	return ret;
	}

	/*
	* linux rtc-module does not support wday alarm
	* and only 24h time mode supported indeed
	*/
	static int ds3232_set_alarm(struct device dev, struct rtc_wkalrm alarm)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct ds3232 *ds3232 = i2c_get_clientdata(client);
	int control, stat;
	int ret;
	u8 buf[4];

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

	mutex_lock(&ds3232->mutex);

	buf[0] = bin2bcd(alarm->time.tm_sec);
	buf[1] = bin2bcd(alarm->time.tm_min);
	buf[2] = bin2bcd(alarm->time.tm_hour);
	buf[3] = bin2bcd(alarm->time.tm_mday);

	/* clear alarm interrupt enable bit */
	ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
	if (ret < 0)
	goto out;
	control = ret;
	control &= ~(DS3232_REG_CR_A1IE \| DS3232_REG_CR_A2IE);
	ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
	if (ret < 0)
	goto out;

	/* clear any pending alarm flag */
	ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
	if (ret < 0)
	goto out;
	stat = ret;
	stat &= ~(DS3232_REG_SR_A1F \| DS3232_REG_SR_A2F);
	ret = i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);
	if (ret < 0)
	goto out;

	ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);

	if (alarm->enabled) {
	control \|= DS3232_REG_CR_A1IE;
	ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
	}
	out:
	mutex_unlock(&ds3232->mutex);
	return ret;
	}

	static void ds3232_update_alarm(struct i2c_client *client)
	{
	struct ds3232 *ds3232 = i2c_get_clientdata(client);
	int control;
	int ret;
	u8 buf[4];

	mutex_lock(&ds3232->mutex);

	ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
	if (ret < 0)
	goto unlock;

	buf[0] = bcd2bin(buf[0]) < 0 \|\| (ds3232->rtc->irq_data & RTC_UF) ?
	0x80 : buf[0];
	buf[1] = bcd2bin(buf[1]) < 0 \|\| (ds3232->rtc->irq_data & RTC_UF) ?
	0x80 : buf[1];
	buf[2] = bcd2bin(buf[2]) < 0 \|\| (ds3232->rtc->irq_data & RTC_UF) ?
	0x80 : buf[2];
	buf[3] = bcd2bin(buf[3]) < 0 \|\| (ds3232->rtc->irq_data & RTC_UF) ?
	0x80 : buf[3];

	ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
	if (ret < 0)
	goto unlock;

	control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
	if (control < 0)
	goto unlock;

	if (ds3232->rtc->irq_data & (RTC_AF \| RTC_UF))
	/* enable alarm1 interrupt */
	control \|= DS3232_REG_CR_A1IE;
	else
	/* disable alarm1 interrupt */
	control &= ~(DS3232_REG_CR_A1IE);
	i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);

	unlock:
	mutex_unlock(&ds3232->mutex);
	}

	static int ds3232_alarm_irq_enable(struct device *dev, unsigned int enabled)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct ds3232 *ds3232 = i2c_get_clientdata(client);

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

	if (enabled)
	ds3232->rtc->irq_data \|= RTC_AF;
	else
	ds3232->rtc->irq_data &= ~RTC_AF;

	ds3232_update_alarm(client);
	return 0;
	}

	static int ds3232_update_irq_enable(struct device *dev, unsigned int enabled)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct ds3232 *ds3232 = i2c_get_clientdata(client);

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

	if (enabled)
	ds3232->rtc->irq_data \|= RTC_UF;
	else
	ds3232->rtc->irq_data &= ~RTC_UF;

	ds3232_update_alarm(client);
	return 0;
	}

	static irqreturn_t ds3232_irq(int irq, void *dev_id)
	{
	struct i2c_client *client = dev_id;
	struct ds3232 *ds3232 = i2c_get_clientdata(client);

	disable_irq_nosync(irq);
	schedule_work(&ds3232->work);
	return IRQ_HANDLED;
	}

	static void ds3232_work(struct work_struct *work)
	{
	struct ds3232 *ds3232 = container_of(work, struct ds3232, work);
	struct i2c_client *client = ds3232->client;
	int stat, control;

	mutex_lock(&ds3232->mutex);

	stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
	if (stat < 0)
	goto unlock;

	if (stat & DS3232_REG_SR_A1F) {
	control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
	if (control < 0)
	goto out;
	/* disable alarm1 interrupt */
	control &= ~(DS3232_REG_CR_A1IE);
	i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);

	/* clear the alarm pend flag */
	stat &= ~DS3232_REG_SR_A1F;
	i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);

	rtc_update_irq(ds3232->rtc, 1, RTC_AF \| RTC_IRQF);
	}

	out:
	if (!ds3232->exiting)
	enable_irq(client->irq);
	unlock:
	mutex_unlock(&ds3232->mutex);
	}

	static const struct rtc_class_ops ds3232_rtc_ops = {
	.read_time = ds3232_read_time,
	.set_time = ds3232_set_time,
	.read_alarm = ds3232_read_alarm,
	.set_alarm = ds3232_set_alarm,
	.alarm_irq_enable = ds3232_alarm_irq_enable,
	.update_irq_enable = ds3232_update_irq_enable,
	};

	static int __devinit ds3232_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct ds3232 *ds3232;
	int ret;

	ds3232 = kzalloc(sizeof(struct ds3232), GFP_KERNEL);
	if (!ds3232)
	return -ENOMEM;

	ds3232->client = client;
	i2c_set_clientdata(client, ds3232);

	INIT_WORK(&ds3232->work, ds3232_work);
	mutex_init(&ds3232->mutex);

	ret = ds3232_check_rtc_status(client);
	if (ret)
	goto out_free;

	ds3232->rtc = rtc_device_register(client->name, &client->dev,
	&ds3232_rtc_ops, THIS_MODULE);
	if (IS_ERR(ds3232->rtc)) {
	ret = PTR_ERR(ds3232->rtc);
	dev_err(&client->dev, "unable to register the class device\n");
	goto out_irq;
	}

	if (client->irq >= 0) {
	ret = request_irq(client->irq, ds3232_irq, 0,
	"ds3232", client);
	if (ret) {
	dev_err(&client->dev, "unable to request IRQ\n");
	goto out_free;
	}
	}

	return 0;

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

	out_free:
	kfree(ds3232);
	return ret;
	}

	static int __devexit ds3232_remove(struct i2c_client *client)
	{
	struct ds3232 *ds3232 = i2c_get_clientdata(client);

	if (client->irq >= 0) {
	mutex_lock(&ds3232->mutex);
	ds3232->exiting = 1;
	mutex_unlock(&ds3232->mutex);

	free_irq(client->irq, client);
	flush_scheduled_work();
	}

	rtc_device_unregister(ds3232->rtc);
	kfree(ds3232);
	return 0;
	}

	static const struct i2c_device_id ds3232_id[] = {
	{ "ds3232", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, ds3232_id);

	static struct i2c_driver ds3232_driver = {
	.driver = {
	.name = "rtc-ds3232",
	.owner = THIS_MODULE,
	},
	.probe = ds3232_probe,
	.remove = __devexit_p(ds3232_remove),
	.id_table = ds3232_id,
	};

	static int __init ds3232_init(void)
	{
	return i2c_add_driver(&ds3232_driver);
	}

	static void __exit ds3232_exit(void)
	{
	i2c_del_driver(&ds3232_driver);
	}

	module_init(ds3232_init);
	module_exit(ds3232_exit);

	MODULE_AUTHOR("Srikanth Srinivasan <srikanth.srinivasan@freescale.com>");
	MODULE_DESCRIPTION("Maxim/Dallas DS3232 RTC Driver");
	MODULE_LICENSE("GPL");