path: root/drivers/rtc/interface.c

/*
 * 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/module.h>
#include <linux/log2.h>
#include <linux/workqueue.h>

#define CREATE_TRACE_POINTS
#include <trace/events/rtc.h>

static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer);
static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer);

static void rtc_add_offset(struct rtc_device *rtc, struct rtc_time *tm)
{
	time64_t secs;

	if (!rtc->offset_secs)
		return;

	secs = rtc_tm_to_time64(tm);

	/*
	 * Since the reading time values from RTC device are always in the RTC
	 * original valid range, but we need to skip the overlapped region
	 * between expanded range and original range, which is no need to add
	 * the offset.
	 */
	if ((rtc->start_secs > rtc->range_min && secs >= rtc->start_secs) ||
	    (rtc->start_secs < rtc->range_min &&
	     secs <= (rtc->start_secs + rtc->range_max - rtc->range_min)))
		return;

	rtc_time64_to_tm(secs + rtc->offset_secs, tm);
}

static void rtc_subtract_offset(struct rtc_device *rtc, struct rtc_time *tm)
{
	time64_t secs;

	if (!rtc->offset_secs)
		return;

	secs = rtc_tm_to_time64(tm);

	/*
	 * If the setting time values are in the valid range of RTC hardware
	 * device, then no need to subtract the offset when setting time to RTC
	 * device. Otherwise we need to subtract the offset to make the time
	 * values are valid for RTC hardware device.
	 */
	if (secs >= rtc->range_min && secs <= rtc->range_max)
		return;

	rtc_time64_to_tm(secs - rtc->offset_secs, tm);
}

static int rtc_valid_range(struct rtc_device *rtc, struct rtc_time *tm)
{
	if (rtc->range_min != rtc->range_max) {
		time64_t time = rtc_tm_to_time64(tm);
		time64_t range_min = rtc->set_start_time ? rtc->start_secs :
			rtc->range_min;
		time64_t range_max = rtc->set_start_time ?
			(rtc->start_secs + rtc->range_max - rtc->range_min) :
			rtc->range_max;

		if (time < range_min || time > range_max)
			return -ERANGE;
	}

	return 0;
}

static int __rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
{
	int 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);
		if (err < 0) {
			dev_dbg(&rtc->dev, "read_time: fail to read: %d\n",
				err);
			return err;
		}

		rtc_add_offset(rtc, tm);

		err = rtc_valid_tm(tm);
		if (err < 0)
			dev_dbg(&rtc->dev, "read_time: rtc_time isn't valid\n");
	}
	return err;
}

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;

	err = __rtc_read_time(rtc, tm);
	mutex_unlock(&rtc->ops_lock);

	trace_rtc_read_time(rtc_tm_to_time64(tm), err);
	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 = rtc_valid_range(rtc, tm);
	if (err)
		return err;

	rtc_subtract_offset(rtc, tm);

	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_mmss64) {
		time64_t secs64 = rtc_tm_to_time64(tm);

		err = rtc->ops->set_mmss64(rtc->dev.parent, secs64);
	} else if (rtc->ops->set_mmss) {
		time64_t secs64 = rtc_tm_to_time64(tm);
		err = rtc->ops->set_mmss(rtc->dev.parent,