drivers/rtc/interface.c - kernel/prism - Git at Google

 /*
  * RTC subsystem, interface functions
  *
  * Copyright (C) 2005 Tower Technologies
  * Author: Alessandro Zummo <a.zummo@towertech.it>
  *
  * based on arch/arm/common/rtctime.c
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
 */

 #include <linux/rtc.h>
 #include <linux/sched.h>
 #include <linux/log2.h>

 int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
 {
 	int err;

 	err = mutex_lock_interruptible(&rtc->ops_lock);
 	if (err)
 		return err;

 	if (!rtc->ops)
 		err = -ENODEV;
 	else if (!rtc->ops->read_time)
 		err = -EINVAL;
 	else {
 		memset(tm, 0, sizeof(struct rtc_time));
 		err = rtc->ops->read_time(rtc->dev.parent, tm);
 	}

 	mutex_unlock(&rtc->ops_lock);
 	return err;
 }
 EXPORT_SYMBOL_GPL(rtc_read_time);

 int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm)
 {
 	int err;

 	err = rtc_valid_tm(tm);
 	if (err != 0)
 		return err;

 	err = mutex_lock_interruptible(&rtc->ops_lock);
 	if (err)
 		return err;

 	if (!rtc->ops)
 		err = -ENODEV;
 	else if (rtc->ops->set_time)
 		err = rtc->ops->set_time(rtc->dev.parent, tm);
 	else if (rtc->ops->set_mmss) {
 		unsigned long secs;
 		err = rtc_tm_to_time(tm, &secs);
 		if (err == 0)
 			err = rtc->ops->set_mmss(rtc->dev.parent, secs);
 	} else
 		err = -EINVAL;

 	mutex_unlock(&rtc->ops_lock);
 	return err;
 }
 EXPORT_SYMBOL_GPL(rtc_set_time);

 int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs)
 {
 	int err;

 	err = mutex_lock_interruptible(&rtc->ops_lock);
 	if (err)
 		return err;

 	if (!rtc->ops)
 		err = -ENODEV;
 	else if (rtc->ops->set_mmss)
 		err = rtc->ops->set_mmss(rtc->dev.parent, secs);
 	else if (rtc->ops->read_time && rtc->ops->set_time) {
 		struct rtc_time new, old;

 		err = rtc->ops->read_time(rtc->dev.parent, &old);
 		if (err == 0) {
 			rtc_time_to_tm(secs, &new);

 			/*
 			 * avoid writing when we're going to change the day of
 			 * the month. We will retry in the next minute. This
 			 * basically means that if the RTC must not drift
 			 * by more than 1 minute in 11 minutes.
 			 */
 			if (!((old.tm_hour == 23 && old.tm_min == 59) ||
 				(new.tm_hour == 23 && new.tm_min == 59)))
 				err = rtc->ops->set_time(rtc->dev.parent,
 						&new);
 		}
 	}
 	else
 		err = -EINVAL;

 	mutex_unlock(&rtc->ops_lock);

 	return err;
 }
 EXPORT_SYMBOL_GPL(rtc_set_mmss);

 static int rtc_read_alarm_internal(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 {
 	int err;

 	err = mutex_lock_interruptible(&rtc->ops_lock);
 	if (err)
 		return err;

 	if (rtc->ops == NULL)
 		err = -ENODEV;
 	else if (!rtc->ops->read_alarm)
 		err = -EINVAL;
 	else {
 		memset(alarm, 0, sizeof(struct rtc_wkalrm));
 		err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
 	}

 	mutex_unlock(&rtc->ops_lock);
 	return err;
 }

 int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 {
 	int err;
 	struct rtc_time before, now;
 	int first_time = 1;
 	unsigned long t_now, t_alm;
 	enum { none, day, month, year } missing = none;
 	unsigned days;

 	/* The lower level RTC driver may return -1 in some fields,
 	 * creating invalid alarm->time values, for reasons like:
 	 *
 	 *   - The hardware may not be capable of filling them in;
 	 *     many alarms match only on time-of-day fields, not
 	 *     day/month/year calendar data.
 	 *
 	 *   - Some hardware uses illegal values as "wildcard" match
 	 *     values, which non-Linux firmware (like a BIOS) may try
 	 *     to set up as e.g. "alarm 15 minutes after each hour".
 	 *     Linux uses only oneshot alarms.
 	 *
 	 * When we see that here, we deal with it by using values from
 	 * a current RTC timestamp for any missing (-1) values.  The
 	 * RTC driver prevents "periodic alarm" modes.
 	 *
 	 * But this can be racey, because some fields of the RTC timestamp
 	 * may have wrapped in the interval since we read the RTC alarm,
 	 * which would lead to us inserting inconsistent values in place
 	 * of the -1 fields.
 	 *
 	 * Reading the alarm and timestamp in the reverse sequence
 	 * would have the same race condition, and not solve the issue.
 	 *
 	 * So, we must first read the RTC timestamp,
 	 * then read the RTC alarm value,
 	 * and then read a second RTC timestamp.
 	 *
 	 * If any fields of the second timestamp have changed
 	 * when compared with the first timestamp, then we know
 	 * our timestamp may be inconsistent with that used by
 	 * the low-level rtc_read_alarm_internal() function.
 	 *
 	 * So, when the two timestamps disagree, we just loop and do
 	 * the process again to get a fully consistent set of values.
 	 *
 	 * This could all instead be done in the lower level driver,
 	 * but since more than one lower level RTC implementation needs it,
 	 * then it's probably best best to do it here instead of there..
 	 */

 	/* Get the "before" timestamp */
 	err = rtc_read_time(rtc, &before);
 	if (err < 0)
 		return err;
 	do {
 		if (!first_time)
 			memcpy(&before, &now, sizeof(struct rtc_time));
 		first_time = 0;

 		/* get the RTC alarm values, which may be incomplete */
 		err = rtc_read_alarm_internal(rtc, alarm);
 		if (err)
 			return err;
 		if (!alarm->enabled)
 			return 0;

 		/* full-function RTCs won't have such missing fields */
 		if (rtc_valid_tm(&alarm->time) == 0)
 			return 0;

 		/* get the "after" timestamp, to detect wrapped fields */
 		err = rtc_read_time(rtc, &now);
 		if (err < 0)
 			return err;

 		/* note that tm_sec is a "don't care" value here: */
 	} while (   before.tm_min   != now.tm_min
 		 || before.tm_hour  != now.tm_hour
 		 || before.tm_mon   != now.tm_mon
 		 || before.tm_year  != now.tm_year);

 	/* Fill in the missing alarm fields using the timestamp; we
 	 * know there's at least one since alarm->time is invalid.
 	 */
 	if (alarm->time.tm_sec == -1)
 		alarm->time.tm_sec = now.tm_sec;
 	if (alarm->time.tm_min == -1)
 		alarm->time.tm_min = now.tm_min;
 	if (alarm->time.tm_hour == -1)
 		alarm->time.tm_hour = now.tm_hour;

 	/* For simplicity, only support date rollover for now */
 	if (alarm->time.tm_mday == -1) {
 		alarm->time.tm_mday = now.tm_mday;
 		missing = day;
 	}
 	if (alarm->time.tm_mon == -1) {
 		alarm->time.tm_mon = now.tm_mon;
 		if (missing == none)
 			missing = month;
 	}
 	if (alarm->time.tm_year == -1) {
 		alarm->time.tm_year = now.tm_year;
 		if (missing == none)
 			missing = year;
 	}

 	/* with luck, no rollover is needed */
 	rtc_tm_to_time(&now, &t_now);
 	rtc_tm_to_time(&alarm->time, &t_alm);
 	if (t_now < t_alm)
 		goto done;

 	switch (missing) {

 	/* 24 hour rollover ... if it's now 10am Monday, an alarm that
 	 * that will trigger at 5am will do so at 5am Tuesday, which
 	 * could also be in the next month or year.  This is a common
 	 * case, especially for PCs.
 	 */
 	case day:
 		dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
 		t_alm += 24 * 60 * 60;
 		rtc_time_to_tm(t_alm, &alarm->time);
 		break;

 	/* Month rollover ... if it's the 31th, an alarm on the 3rd will
 	 * be next month.  An alarm matching on the 30th, 29th, or 28th
 	 * may end up in the month after that!  Many newer PCs support
 	 * this type of alarm.
 	 */
 	case month:
 		dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
 		do {
 			if (alarm->time.tm_mon < 11)
 				alarm->time.tm_mon++;
 			else {
 				alarm->time.tm_mon = 0;
 				alarm->time.tm_year++;
 			}
 			days = rtc_month_days(alarm->time.tm_mon,
 					alarm->time.tm_year);
 		} while (days < alarm->time.tm_mday);
 		break;

 	/* Year rollover ... easy except for leap years! */
 	case year:
 		dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
 		do {
 			alarm->time.tm_year++;
 		} while (rtc_valid_tm(&alarm->time) != 0);
 		break;

 	default:
 		dev_warn(&rtc->dev, "alarm rollover not handled\n");
 	}

 done:
 	return 0;
 }
 EXPORT_SYMBOL_GPL(rtc_read_alarm);

 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 {
 	int err;

 	err = rtc_valid_tm(&alarm->time);
 	if (err != 0)
 		return err;

 	err = mutex_lock_interruptible(&rtc->ops_lock);
 	if (err)
 		return err;

 	if (!rtc->ops)
 		err = -ENODEV;
 	else if (!rtc->ops->set_alarm)
 		err = -EINVAL;
 	else
 		err = rtc->ops->set_alarm(rtc->dev.parent, alarm);

 	mutex_unlock(&rtc->ops_lock);
 	return err;
 }
 EXPORT_SYMBOL_GPL(rtc_set_alarm);

 int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 {
 	int err = mutex_lock_interruptible(&rtc->ops_lock);
 	if (err)
 		return err;

 	if (!rtc->ops)
 		err = -ENODEV;
 	else if (!rtc->ops->alarm_irq_enable)
 		err = -EINVAL;
 	else
 		err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);

 	mutex_unlock(&rtc->ops_lock);
 	return err;
 }
 EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);

 int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
 {
 	int err = mutex_lock_interruptible(&rtc->ops_lock);
 	if (err)
 		return err;

 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 	if (enabled == 0 && rtc->uie_irq_active) {
 		mutex_unlock(&rtc->ops_lock);
 		return rtc_dev_update_irq_enable_emul(rtc, enabled);
 	}
 #endif

 	if (!rtc->ops)
 		err = -ENODEV;
 	else if (!rtc->ops->update_irq_enable)
 		err = -EINVAL;
 	else
 		err = rtc->ops->update_irq_enable(rtc->dev.parent, enabled);

 	mutex_unlock(&rtc->ops_lock);

 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 	/*
 	 * Enable emulation if the driver did not provide
 	 * the update_irq_enable function pointer or if returned
 	 * -EINVAL to signal that it has been configured without
 	 * interrupts or that are not available at the moment.
 	 */
 	if (err == -EINVAL)
 		err = rtc_dev_update_irq_enable_emul(rtc, enabled);
 #endif
 	return err;
 }
 EXPORT_SYMBOL_GPL(rtc_update_irq_enable);

 /**
  * rtc_update_irq - report RTC periodic, alarm, and/or update irqs
  * @rtc: the rtc device
  * @num: how many irqs are being reported (usually one)
  * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
  * Context: any
  */
 void rtc_update_irq(struct rtc_device *rtc,
 		unsigned long num, unsigned long events)
 {
 	unsigned long flags;

 	spin_lock_irqsave(&rtc->irq_lock, flags);
 	rtc->irq_data = (rtc->irq_data + (num << 8)) | events;
 	spin_unlock_irqrestore(&rtc->irq_lock, flags);

 	spin_lock_irqsave(&rtc->irq_task_lock, flags);
 	if (rtc->irq_task)
 		rtc->irq_task->func(rtc->irq_task->private_data);
 	spin_unlock_irqrestore(&rtc->irq_task_lock, flags);

 	wake_up_interruptible(&rtc->irq_queue);
 	kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
 }
 EXPORT_SYMBOL_GPL(rtc_update_irq);

 static int __rtc_match(struct device *dev, void *data)
 {
 	char *name = (char *)data;

 	if (strcmp(dev_name(dev), name) == 0)
 		return 1;
 	return 0;
 }

 struct rtc_device *rtc_class_open(char *name)
 {
 	struct device *dev;
 	struct rtc_device *rtc = NULL;

 	dev = class_find_device(rtc_class, NULL, name, __rtc_match);
 	if (dev)
 		rtc = to_rtc_device(dev);

 	if (rtc) {
 		if (!try_module_get(rtc->owner)) {
 			put_device(dev);
 			rtc = NULL;
 		}
 	}

 	return rtc;
 }
 EXPORT_SYMBOL_GPL(rtc_class_open);

 void rtc_class_close(struct rtc_device *rtc)
 {
 	module_put(rtc->owner);
 	put_device(&rtc->dev);
 }
 EXPORT_SYMBOL_GPL(rtc_class_close);

 int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
 {
 	int retval = -EBUSY;

 	if (task == NULL || task->func == NULL)
 		return -EINVAL;

 	/* Cannot register while the char dev is in use */
 	if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
 		return -EBUSY;

 	spin_lock_irq(&rtc->irq_task_lock);
 	if (rtc->irq_task == NULL) {
 		rtc->irq_task = task;
 		retval = 0;
 	}
 	spin_unlock_irq(&rtc->irq_task_lock);

 	clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);

 	return retval;
 }
 EXPORT_SYMBOL_GPL(rtc_irq_register);

 void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
 {
 	spin_lock_irq(&rtc->irq_task_lock);
 	if (rtc->irq_task == task)
 		rtc->irq_task = NULL;
 	spin_unlock_irq(&rtc->irq_task_lock);
 }
 EXPORT_SYMBOL_GPL(rtc_irq_unregister);

 /**
  * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
  * @rtc: the rtc device
  * @task: currently registered with rtc_irq_register()
  * @enabled: true to enable periodic IRQs
  * Context: any
  *
  * Note that rtc_irq_set_freq() should previously have been used to
  * specify the desired frequency of periodic IRQ task->func() callbacks.
  */
 int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled)
 {
 	int err = 0;
 	unsigned long flags;

 	if (rtc->ops->irq_set_state == NULL)
 		return -ENXIO;

 	spin_lock_irqsave(&rtc->irq_task_lock, flags);
 	if (rtc->irq_task != NULL && task == NULL)
 		err = -EBUSY;
 	if (rtc->irq_task != task)
 		err = -EACCES;
 	spin_unlock_irqrestore(&rtc->irq_task_lock, flags);

 	if (err == 0)
 		err = rtc->ops->irq_set_state(rtc->dev.parent, enabled);

 	return err;
 }
 EXPORT_SYMBOL_GPL(rtc_irq_set_state);

 /**
  * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
  * @rtc: the rtc device
  * @task: currently registered with rtc_irq_register()
  * @freq: positive frequency with which task->func() will be called
  * Context: any
  *
  * Note that rtc_irq_set_state() is used to enable or disable the
  * periodic IRQs.
  */
 int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
 {
 	int err = 0;
 	unsigned long flags;

 	if (rtc->ops->irq_set_freq == NULL)
 		return -ENXIO;

 	spin_lock_irqsave(&rtc->irq_task_lock, flags);
 	if (rtc->irq_task != NULL && task == NULL)
 		err = -EBUSY;
 	if (rtc->irq_task != task)
 		err = -EACCES;
 	spin_unlock_irqrestore(&rtc->irq_task_lock, flags);

 	if (err == 0) {
 		err = rtc->ops->irq_set_freq(rtc->dev.parent, freq);
 		if (err == 0)
 			rtc->irq_freq = freq;
 	}
 	return err;
 }
 EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
	/*
	* RTC subsystem, interface functions
	*
	* Copyright (C) 2005 Tower Technologies
	* Author: Alessandro Zummo <a.zummo@towertech.it>
	*
	* based on arch/arm/common/rtctime.c
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*/

	#include <linux/rtc.h>
	#include <linux/sched.h>
	#include <linux/log2.h>

	int rtc_read_time(struct rtc_device rtc, struct rtc_time tm)
	{
	int err;

	err = mutex_lock_interruptible(&rtc->ops_lock);
	if (err)
	return err;

	if (!rtc->ops)
	err = -ENODEV;
	else if (!rtc->ops->read_time)
	err = -EINVAL;
	else {
	memset(tm, 0, sizeof(struct rtc_time));
	err = rtc->ops->read_time(rtc->dev.parent, tm);
	}

	mutex_unlock(&rtc->ops_lock);
	return err;
	}
	EXPORT_SYMBOL_GPL(rtc_read_time);

	int rtc_set_time(struct rtc_device rtc, struct rtc_time tm)
	{
	int err;

	err = rtc_valid_tm(tm);
	if (err != 0)
	return err;

	err = mutex_lock_interruptible(&rtc->ops_lock);
	if (err)
	return err;

	if (!rtc->ops)
	err = -ENODEV;
	else if (rtc->ops->set_time)
	err = rtc->ops->set_time(rtc->dev.parent, tm);
	else if (rtc->ops->set_mmss) {
	unsigned long secs;
	err = rtc_tm_to_time(tm, &secs);
	if (err == 0)
	err = rtc->ops->set_mmss(rtc->dev.parent, secs);
	} else
	err = -EINVAL;

	mutex_unlock(&rtc->ops_lock);
	return err;
	}
	EXPORT_SYMBOL_GPL(rtc_set_time);

	int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs)
	{
	int err;

	err = mutex_lock_interruptible(&rtc->ops_lock);
	if (err)
	return err;

	if (!rtc->ops)
	err = -ENODEV;
	else if (rtc->ops->set_mmss)
	err = rtc->ops->set_mmss(rtc->dev.parent, secs);
	else if (rtc->ops->read_time && rtc->ops->set_time) {
	struct rtc_time new, old;

	err = rtc->ops->read_time(rtc->dev.parent, &old);
	if (err == 0) {
	rtc_time_to_tm(secs, &new);

	/*
	* avoid writing when we're going to change the day of
	* the month. We will retry in the next minute. This
	* basically means that if the RTC must not drift
	* by more than 1 minute in 11 minutes.
	*/
	if (!((old.tm_hour == 23 && old.tm_min == 59) \|\|
	(new.tm_hour == 23 && new.tm_min == 59)))
	err = rtc->ops->set_time(rtc->dev.parent,
	&new);
	}
	}
	else
	err = -EINVAL;

	mutex_unlock(&rtc->ops_lock);

	return err;
	}
	EXPORT_SYMBOL_GPL(rtc_set_mmss);

	static int rtc_read_alarm_internal(struct rtc_device rtc, struct rtc_wkalrm alarm)
	{
	int err;

	err = mutex_lock_interruptible(&rtc->ops_lock);
	if (err)
	return err;

	if (rtc->ops == NULL)
	err = -ENODEV;
	else if (!rtc->ops->read_alarm)
	err = -EINVAL;
	else {
	memset(alarm, 0, sizeof(struct rtc_wkalrm));
	err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
	}

	mutex_unlock(&rtc->ops_lock);
	return err;
	}

	int rtc_read_alarm(struct rtc_device rtc, struct rtc_wkalrm alarm)
	{
	int err;
	struct rtc_time before, now;
	int first_time = 1;
	unsigned long t_now, t_alm;
	enum { none, day, month, year } missing = none;
	unsigned days;

	/* The lower level RTC driver may return -1 in some fields,
	* creating invalid alarm->time values, for reasons like:
	*
	* - The hardware may not be capable of filling them in;
	* many alarms match only on time-of-day fields, not
	* day/month/year calendar data.
	*
	* - Some hardware uses illegal values as "wildcard" match
	* values, which non-Linux firmware (like a BIOS) may try
	* to set up as e.g. "alarm 15 minutes after each hour".
	* Linux uses only oneshot alarms.
	*
	* When we see that here, we deal with it by using values from
	* a current RTC timestamp for any missing (-1) values. The
	* RTC driver prevents "periodic alarm" modes.
	*
	* But this can be racey, because some fields of the RTC timestamp
	* may have wrapped in the interval since we read the RTC alarm,
	* which would lead to us inserting inconsistent values in place
	* of the -1 fields.
	*
	* Reading the alarm and timestamp in the reverse sequence
	* would have the same race condition, and not solve the issue.
	*
	* So, we must first read the RTC timestamp,
	* then read the RTC alarm value,
	* and then read a second RTC timestamp.
	*
	* If any fields of the second timestamp have changed
	* when compared with the first timestamp, then we know
	* our timestamp may be inconsistent with that used by
	* the low-level rtc_read_alarm_internal() function.
	*
	* So, when the two timestamps disagree, we just loop and do
	* the process again to get a fully consistent set of values.
	*
	* This could all instead be done in the lower level driver,
	* but since more than one lower level RTC implementation needs it,
	* then it's probably best best to do it here instead of there..
	*/

	/* Get the "before" timestamp */
	err = rtc_read_time(rtc, &before);
	if (err < 0)
	return err;
	do {
	if (!first_time)
	memcpy(&before, &now, sizeof(struct rtc_time));
	first_time = 0;

	/* get the RTC alarm values, which may be incomplete */
	err = rtc_read_alarm_internal(rtc, alarm);
	if (err)
	return err;
	if (!alarm->enabled)
	return 0;

	/* full-function RTCs won't have such missing fields */
	if (rtc_valid_tm(&alarm->time) == 0)
	return 0;

	/* get the "after" timestamp, to detect wrapped fields */
	err = rtc_read_time(rtc, &now);
	if (err < 0)
	return err;

	/* note that tm_sec is a "don't care" value here: */
	} while ( before.tm_min != now.tm_min
	\|\| before.tm_hour != now.tm_hour
	\|\| before.tm_mon != now.tm_mon
	\|\| before.tm_year != now.tm_year);

	/* Fill in the missing alarm fields using the timestamp; we
	* know there's at least one since alarm->time is invalid.
	*/
	if (alarm->time.tm_sec == -1)
	alarm->time.tm_sec = now.tm_sec;
	if (alarm->time.tm_min == -1)
	alarm->time.tm_min = now.tm_min;
	if (alarm->time.tm_hour == -1)
	alarm->time.tm_hour = now.tm_hour;

	/* For simplicity, only support date rollover for now */
	if (alarm->time.tm_mday == -1) {
	alarm->time.tm_mday = now.tm_mday;
	missing = day;
	}
	if (alarm->time.tm_mon == -1) {
	alarm->time.tm_mon = now.tm_mon;
	if (missing == none)
	missing = month;
	}
	if (alarm->time.tm_year == -1) {
	alarm->time.tm_year = now.tm_year;
	if (missing == none)
	missing = year;
	}

	/* with luck, no rollover is needed */
	rtc_tm_to_time(&now, &t_now);
	rtc_tm_to_time(&alarm->time, &t_alm);
	if (t_now < t_alm)
	goto done;

	switch (missing) {

	/* 24 hour rollover ... if it's now 10am Monday, an alarm that
	* that will trigger at 5am will do so at 5am Tuesday, which
	* could also be in the next month or year. This is a common
	* case, especially for PCs.
	*/
	case day:
	dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
	t_alm += 24 * 60 * 60;
	rtc_time_to_tm(t_alm, &alarm->time);
	break;

	/* Month rollover ... if it's the 31th, an alarm on the 3rd will
	* be next month. An alarm matching on the 30th, 29th, or 28th
	* may end up in the month after that! Many newer PCs support
	* this type of alarm.
	*/
	case month:
	dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
	do {
	if (alarm->time.tm_mon < 11)
	alarm->time.tm_mon++;
	else {
	alarm->time.tm_mon = 0;
	alarm->time.tm_year++;
	}
	days = rtc_month_days(alarm->time.tm_mon,
	alarm->time.tm_year);
	} while (days < alarm->time.tm_mday);
	break;

	/* Year rollover ... easy except for leap years! */
	case year:
	dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
	do {
	alarm->time.tm_year++;
	} while (rtc_valid_tm(&alarm->time) != 0);
	break;

	default:
	dev_warn(&rtc->dev, "alarm rollover not handled\n");
	}

	done:
	return 0;
	}
	EXPORT_SYMBOL_GPL(rtc_read_alarm);

	int rtc_set_alarm(struct rtc_device rtc, struct rtc_wkalrm alarm)
	{
	int err;

	err = rtc_valid_tm(&alarm->time);
	if (err != 0)
	return err;

	err = mutex_lock_interruptible(&rtc->ops_lock);
	if (err)
	return err;

	if (!rtc->ops)
	err = -ENODEV;
	else if (!rtc->ops->set_alarm)
	err = -EINVAL;
	else
	err = rtc->ops->set_alarm(rtc->dev.parent, alarm);

	mutex_unlock(&rtc->ops_lock);
	return err;
	}
	EXPORT_SYMBOL_GPL(rtc_set_alarm);

	int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
	{
	int err = mutex_lock_interruptible(&rtc->ops_lock);
	if (err)
	return err;

	if (!rtc->ops)
	err = -ENODEV;
	else if (!rtc->ops->alarm_irq_enable)
	err = -EINVAL;
	else
	err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);

	mutex_unlock(&rtc->ops_lock);
	return err;
	}
	EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);

	int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
	{
	int err = mutex_lock_interruptible(&rtc->ops_lock);
	if (err)
	return err;

	#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
	if (enabled == 0 && rtc->uie_irq_active) {
	mutex_unlock(&rtc->ops_lock);
	return rtc_dev_update_irq_enable_emul(rtc, enabled);
	}
	#endif

	if (!rtc->ops)
	err = -ENODEV;
	else if (!rtc->ops->update_irq_enable)
	err = -EINVAL;
	else
	err = rtc->ops->update_irq_enable(rtc->dev.parent, enabled);

	mutex_unlock(&rtc->ops_lock);

	#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
	/*
	* Enable emulation if the driver did not provide
	* the update_irq_enable function pointer or if returned
	* -EINVAL to signal that it has been configured without
	* interrupts or that are not available at the moment.
	*/
	if (err == -EINVAL)
	err = rtc_dev_update_irq_enable_emul(rtc, enabled);
	#endif
	return err;
	}
	EXPORT_SYMBOL_GPL(rtc_update_irq_enable);

	/**
	* rtc_update_irq - report RTC periodic, alarm, and/or update irqs
	* @rtc: the rtc device
	* @num: how many irqs are being reported (usually one)
	* @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
	* Context: any
	*/
	void rtc_update_irq(struct rtc_device *rtc,
	unsigned long num, unsigned long events)
	{
	unsigned long flags;

	spin_lock_irqsave(&rtc->irq_lock, flags);
	rtc->irq_data = (rtc->irq_data + (num << 8)) \| events;
	spin_unlock_irqrestore(&rtc->irq_lock, flags);

	spin_lock_irqsave(&rtc->irq_task_lock, flags);
	if (rtc->irq_task)
	rtc->irq_task->func(rtc->irq_task->private_data);
	spin_unlock_irqrestore(&rtc->irq_task_lock, flags);

	wake_up_interruptible(&rtc->irq_queue);
	kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
	}
	EXPORT_SYMBOL_GPL(rtc_update_irq);

	static int __rtc_match(struct device dev, void data)
	{
	char name = (char )data;

	if (strcmp(dev_name(dev), name) == 0)
	return 1;
	return 0;
	}

	struct rtc_device rtc_class_open(char name)
	{
	struct device *dev;
	struct rtc_device *rtc = NULL;

	dev = class_find_device(rtc_class, NULL, name, __rtc_match);
	if (dev)
	rtc = to_rtc_device(dev);

	if (rtc) {
	if (!try_module_get(rtc->owner)) {
	put_device(dev);
	rtc = NULL;
	}
	}

	return rtc;
	}
	EXPORT_SYMBOL_GPL(rtc_class_open);

	void rtc_class_close(struct rtc_device *rtc)
	{
	module_put(rtc->owner);
	put_device(&rtc->dev);
	}
	EXPORT_SYMBOL_GPL(rtc_class_close);

	int rtc_irq_register(struct rtc_device rtc, struct rtc_task task)
	{
	int retval = -EBUSY;

	if (task == NULL \|\| task->func == NULL)
	return -EINVAL;

	/* Cannot register while the char dev is in use */
	if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
	return -EBUSY;

	spin_lock_irq(&rtc->irq_task_lock);
	if (rtc->irq_task == NULL) {
	rtc->irq_task = task;
	retval = 0;
	}
	spin_unlock_irq(&rtc->irq_task_lock);

	clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);

	return retval;
	}
	EXPORT_SYMBOL_GPL(rtc_irq_register);

	void rtc_irq_unregister(struct rtc_device rtc, struct rtc_task task)
	{
	spin_lock_irq(&rtc->irq_task_lock);
	if (rtc->irq_task == task)
	rtc->irq_task = NULL;
	spin_unlock_irq(&rtc->irq_task_lock);
	}
	EXPORT_SYMBOL_GPL(rtc_irq_unregister);

	/**
	* rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
	* @rtc: the rtc device
	* @task: currently registered with rtc_irq_register()
	* @enabled: true to enable periodic IRQs
	* Context: any
	*
	* Note that rtc_irq_set_freq() should previously have been used to
	* specify the desired frequency of periodic IRQ task->func() callbacks.
	*/
	int rtc_irq_set_state(struct rtc_device rtc, struct rtc_task task, int enabled)
	{
	int err = 0;
	unsigned long flags;

	if (rtc->ops->irq_set_state == NULL)
	return -ENXIO;

	spin_lock_irqsave(&rtc->irq_task_lock, flags);
	if (rtc->irq_task != NULL && task == NULL)
	err = -EBUSY;
	if (rtc->irq_task != task)
	err = -EACCES;
	spin_unlock_irqrestore(&rtc->irq_task_lock, flags);

	if (err == 0)
	err = rtc->ops->irq_set_state(rtc->dev.parent, enabled);

	return err;
	}
	EXPORT_SYMBOL_GPL(rtc_irq_set_state);

	/**
	* rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
	* @rtc: the rtc device
	* @task: currently registered with rtc_irq_register()
	* @freq: positive frequency with which task->func() will be called
	* Context: any
	*
	* Note that rtc_irq_set_state() is used to enable or disable the
	* periodic IRQs.
	*/
	int rtc_irq_set_freq(struct rtc_device rtc, struct rtc_task task, int freq)
	{
	int err = 0;
	unsigned long flags;

	if (rtc->ops->irq_set_freq == NULL)
	return -ENXIO;

	spin_lock_irqsave(&rtc->irq_task_lock, flags);
	if (rtc->irq_task != NULL && task == NULL)
	err = -EBUSY;
	if (rtc->irq_task != task)
	err = -EACCES;
	spin_unlock_irqrestore(&rtc->irq_task_lock, flags);

	if (err == 0) {
	err = rtc->ops->irq_set_freq(rtc->dev.parent, freq);
	if (err == 0)
	rtc->irq_freq = freq;
	}
	return err;
	}
	EXPORT_SYMBOL_GPL(rtc_irq_set_freq);