/* * 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/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 = -EINVAL;	else		err = rtc->ops->set_time(rtc->dev.parent, tm); 	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));		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); /** * 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: in_interrupt(), irqs blocked */void rtc_update_irq(struct rtc_device *rtc,		unsigned long num, unsigned long events){	spin_lock(&rtc->irq_lock);	rtc->irq_data = (rtc->irq_data + (num << 8)) | events;	spin_unlock(&rtc->irq_lock); 	spin_lock(&rtc->irq_task_lock);	if (rtc->irq_task)		rtc->irq_task->func(rtc->irq_task->private_data);	spin_unlock(&rtc->irq_task_lock); 	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 (strncmp(dev->bus_id, name, BUS_ID_SIZE) == 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; 	if (!is_power_of_2(freq))		return -EINVAL; 	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);