/* * 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 -EBUSY; 	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 -EBUSY; 	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 -EBUSY; 	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 -EBUSY; 	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; 	/* The lower level RTC driver may not be capable of filling	 * in all fields of the rtc_time struct (eg. rtc-cmos),	 * and so might instead return -1 in some fields.	 * We deal with that here by grabbing a current RTC timestamp	 * and using values from that for any missing (-1) values.	 *	 * 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; 		/* 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		 || before.tm_isdst != now.tm_isdst); 	/* Fill in any missing alarm fields using the timestamp */	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;	if (alarm->time.tm_mday == -1)		alarm->time.tm_mday = now.tm_mday;	if (alarm->time.tm_mon == -1)		alarm->time.tm_mon = now.tm_mon;	if (alarm->time.tm_year == -1)		alarm->time.tm_year = now.tm_year;	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 -EBUSY; 	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); struct rtc_device *rtc_class_open(char *name){	struct device *dev;	struct rtc_device *rtc = NULL; 	down(&rtc_class->sem);	list_for_each_entry(dev, &rtc_class->devices, node) {		if (strncmp(dev->bus_id, name, BUS_ID_SIZE) == 0) {			dev = get_device(dev);			if (dev)				rtc = to_rtc_device(dev);			break;		}	} 	if (rtc) {		if (!try_module_get(rtc->owner)) {			put_device(dev);			rtc = NULL;		}	}	up(&rtc_class->sem); 	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);