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kernel-fxtec-pro1x/drivers/rtc/interface.c
NeilBrown 7523ceed42 RTC: Avoid races between RTC alarm wakeup and suspend. 
If an RTC alarm fires just as suspend is happening, it is possible for
suspend to complete and the alarm to be missed.

To avoid the race, we must register the event with the PM core.

As the event is made visible to userspace through a thread which is
only scheduled by the interrupt, we need a pm_stay_awake/pm_relax
pair preventing suspend from the interrupt until the thread completes
its work.

This makes the pm_wakeup_event() call in cmos_interrupt unnecessary as
it provides suspend protection for all RTCs that use rtc_update_irq.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2012-08-08 20:49:16 +02:00

943 lines
23 KiB
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/*
* 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>
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 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);
}
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);
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);
/* A timer might have just expired */
schedule_work(&rtc->irqwork);
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);
/* A timer might have just expired */
schedule_work(&rtc->irqwork);
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;
/* 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 > 31) {
alarm->time.tm_mday = now.tm_mday;
missing = day;
}
if ((unsigned)alarm->time.tm_mon >= 12) {
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;
}
int rtc_read_alarm(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));
alarm->enabled = rtc->aie_timer.enabled;
alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
}
mutex_unlock(&rtc->ops_lock);
return err;
}
EXPORT_SYMBOL_GPL(rtc_read_alarm);
static int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
{
struct rtc_time tm;
long now, scheduled;
int err;
err = rtc_valid_tm(&alarm->time);
if (err)
return err;
rtc_tm_to_time(&alarm->time, &scheduled);
/* Make sure we're not setting alarms in the past */
err = __rtc_read_time(rtc, &tm);
rtc_tm_to_time(&tm, &now);
if (scheduled <= now)
return -ETIME;
/*
* XXX - We just checked to make sure the alarm time is not
* in the past, but there is still a race window where if
* the is alarm set for the next second and the second ticks
* over right here, before we set the alarm.
*/
if (!rtc->ops)
err = -ENODEV;
else if (!rtc->ops->set_alarm)
err = -EINVAL;
else
err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
return err;
}
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->aie_timer.enabled) {
rtc_timer_remove(rtc, &rtc->aie_timer);
}
rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
rtc->aie_timer.period = ktime_set(0, 0);
if (alarm->enabled) {
err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
}
mutex_unlock(&rtc->ops_lock);
return err;
}
EXPORT_SYMBOL_GPL(rtc_set_alarm);
/* Called once per device from rtc_device_register */
int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
{
int err;
struct rtc_time now;
err = rtc_valid_tm(&alarm->time);
if (err != 0)
return err;
err = rtc_read_time(rtc, &now);
if (err)
return err;
err = mutex_lock_interruptible(&rtc->ops_lock);
if (err)
return err;
rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
rtc->aie_timer.period = ktime_set(0, 0);
/* Alarm has to be enabled & in the futrure for us to enqueue it */
if (alarm->enabled && (rtc_tm_to_ktime(now).tv64 <
rtc->aie_timer.node.expires.tv64)) {
rtc->aie_timer.enabled = 1;
timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
}
mutex_unlock(&rtc->ops_lock);
return err;
}
EXPORT_SYMBOL_GPL(rtc_initialize_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->aie_timer.enabled != enabled) {
if (enabled)
err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
else
rtc_timer_remove(rtc, &rtc->aie_timer);
}
if (err)
/* nothing */;
else 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, 0);
}
#endif
/* make sure we're changing state */
if (rtc->uie_rtctimer.enabled == enabled)
goto out;
if (rtc->uie_unsupported) {
err = -EINVAL;
goto out;
}
if (enabled) {
struct rtc_time tm;
ktime_t now, onesec;
__rtc_read_time(rtc, &tm);
onesec = ktime_set(1, 0);
now = rtc_tm_to_ktime(tm);
rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
rtc->uie_rtctimer.period = ktime_set(1, 0);
err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
} else
rtc_timer_remove(rtc, &rtc->uie_rtctimer);
out:
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_handle_legacy_irq - AIE, UIE and PIE event hook
* @rtc: pointer to the rtc device
*
* This function is called when an AIE, UIE or PIE mode interrupt
* has occurred (or been emulated).
*
* Triggers the registered irq_task function callback.
*/
void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
{
unsigned long flags;
/* mark one irq of the appropriate mode */
spin_lock_irqsave(&rtc->irq_lock, flags);
rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF|mode);
spin_unlock_irqrestore(&rtc->irq_lock, flags);
/* call the task func */
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);
}
/**
* rtc_aie_update_irq - AIE mode rtctimer hook
* @private: pointer to the rtc_device
*
* This functions is called when the aie_timer expires.
*/
void rtc_aie_update_irq(void *private)
{
struct rtc_device *rtc = (struct rtc_device *)private;
rtc_handle_legacy_irq(rtc, 1, RTC_AF);
}
/**
* rtc_uie_update_irq - UIE mode rtctimer hook
* @private: pointer to the rtc_device
*
* This functions is called when the uie_timer expires.
*/
void rtc_uie_update_irq(void *private)
{
struct rtc_device *rtc = (struct rtc_device *)private;
rtc_handle_legacy_irq(rtc, 1, RTC_UF);
}
/**
* rtc_pie_update_irq - PIE mode hrtimer hook
* @timer: pointer to the pie mode hrtimer
*
* This function is used to emulate PIE mode interrupts
* using an hrtimer. This function is called when the periodic
* hrtimer expires.
*/
enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
{
struct rtc_device *rtc;
ktime_t period;
int count;
rtc = container_of(timer, struct rtc_device, pie_timer);
period = ktime_set(0, NSEC_PER_SEC/rtc->irq_freq);
count = hrtimer_forward_now(timer, period);
rtc_handle_legacy_irq(rtc, count, RTC_PF);
return HRTIMER_RESTART;
}
/**
* rtc_update_irq - Triggered when a RTC interrupt occurs.
* @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)
{
pm_stay_awake(rtc->dev.parent);
schedule_work(&rtc->irqwork);
}
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);
static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
{
/*
* We always cancel the timer here first, because otherwise
* we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
* when we manage to start the timer before the callback
* returns HRTIMER_RESTART.
*
* We cannot use hrtimer_cancel() here as a running callback
* could be blocked on rtc->irq_task_lock and hrtimer_cancel()
* would spin forever.
*/
if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
return -1;
if (enabled) {
ktime_t period = ktime_set(0, NSEC_PER_SEC / rtc->irq_freq);
hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
}
return 0;
}
/**
* 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;
retry:
spin_lock_irqsave(&rtc->irq_task_lock, flags);
if (rtc->irq_task != NULL && task == NULL)
err = -EBUSY;
if (rtc->irq_task != task)
err = -EACCES;
if (!err) {
if (rtc_update_hrtimer(rtc, enabled) < 0) {
spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
cpu_relax();
goto retry;
}
rtc->pie_enabled = enabled;
}
spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
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 (freq <= 0 || freq > RTC_MAX_FREQ)
return -EINVAL;
retry:
spin_lock_irqsave(&rtc->irq_task_lock, flags);
if (rtc->irq_task != NULL && task == NULL)
err = -EBUSY;
if (rtc->irq_task != task)
err = -EACCES;
if (!err) {
rtc->irq_freq = freq;
if (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0) {
spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
cpu_relax();
goto retry;
}
}
spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
return err;
}
EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
/**
* rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
* @rtc rtc device
* @timer timer being added.
*
* Enqueues a timer onto the rtc devices timerqueue and sets
* the next alarm event appropriately.
*
* Sets the enabled bit on the added timer.
*
* Must hold ops_lock for proper serialization of timerqueue
*/
static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
{
timer->enabled = 1;
timerqueue_add(&rtc->timerqueue, &timer->node);
if (&timer->node == timerqueue_getnext(&rtc->timerqueue)) {
struct rtc_wkalrm alarm;
int err;
alarm.time = rtc_ktime_to_tm(timer->node.expires);
alarm.enabled = 1;
err = __rtc_set_alarm(rtc, &alarm);
if (err == -ETIME)
schedule_work(&rtc->irqwork);
else if (err) {
timerqueue_del(&rtc->timerqueue, &timer->node);
timer->enabled = 0;
return err;
}
}
return 0;
}
static void rtc_alarm_disable(struct rtc_device *rtc)
{
if (!rtc->ops || !rtc->ops->alarm_irq_enable)
return;
rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
}
/**
* rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
* @rtc rtc device
* @timer timer being removed.
*
* Removes a timer onto the rtc devices timerqueue and sets
* the next alarm event appropriately.
*
* Clears the enabled bit on the removed timer.
*
* Must hold ops_lock for proper serialization of timerqueue
*/
static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
{
struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
timerqueue_del(&rtc->timerqueue, &timer->node);
timer->enabled = 0;
if (next == &timer->node) {
struct rtc_wkalrm alarm;
int err;
next = timerqueue_getnext(&rtc->timerqueue);
if (!next) {
rtc_alarm_disable(rtc);
return;
}
alarm.time = rtc_ktime_to_tm(next->expires);
alarm.enabled = 1;
err = __rtc_set_alarm(rtc, &alarm);
if (err == -ETIME)
schedule_work(&rtc->irqwork);
}
}
/**
* rtc_timer_do_work - Expires rtc timers
* @rtc rtc device
* @timer timer being removed.
*
* Expires rtc timers. Reprograms next alarm event if needed.
* Called via worktask.
*
* Serializes access to timerqueue via ops_lock mutex
*/
void rtc_timer_do_work(struct work_struct *work)
{
struct rtc_timer *timer;
struct timerqueue_node *next;
ktime_t now;
struct rtc_time tm;
struct rtc_device *rtc =
container_of(work, struct rtc_device, irqwork);
mutex_lock(&rtc->ops_lock);
again:
pm_relax(rtc->dev.parent);
__rtc_read_time(rtc, &tm);
now = rtc_tm_to_ktime(tm);
while ((next = timerqueue_getnext(&rtc->timerqueue))) {
if (next->expires.tv64 > now.tv64)
break;
/* expire timer */
timer = container_of(next, struct rtc_timer, node);
timerqueue_del(&rtc->timerqueue, &timer->node);
timer->enabled = 0;
if (timer->task.func)
timer->task.func(timer->task.private_data);
/* Re-add/fwd periodic timers */
if (ktime_to_ns(timer->period)) {
timer->node.expires = ktime_add(timer->node.expires,
timer->period);
timer->enabled = 1;
timerqueue_add(&rtc->timerqueue, &timer->node);
}
}
/* Set next alarm */
if (next) {
struct rtc_wkalrm alarm;
int err;
alarm.time = rtc_ktime_to_tm(next->expires);
alarm.enabled = 1;
err = __rtc_set_alarm(rtc, &alarm);
if (err == -ETIME)
goto again;
} else
rtc_alarm_disable(rtc);
mutex_unlock(&rtc->ops_lock);
}
/* rtc_timer_init - Initializes an rtc_timer
* @timer: timer to be intiialized
* @f: function pointer to be called when timer fires
* @data: private data passed to function pointer
*
* Kernel interface to initializing an rtc_timer.
*/
void rtc_timer_init(struct rtc_timer *timer, void (*f)(void* p), void* data)
{
timerqueue_init(&timer->node);
timer->enabled = 0;
timer->task.func = f;
timer->task.private_data = data;
}
/* rtc_timer_start - Sets an rtc_timer to fire in the future
* @ rtc: rtc device to be used
* @ timer: timer being set
* @ expires: time at which to expire the timer
* @ period: period that the timer will recur
*
* Kernel interface to set an rtc_timer
*/
int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer* timer,
ktime_t expires, ktime_t period)
{
int ret = 0;
mutex_lock(&rtc->ops_lock);
if (timer->enabled)
rtc_timer_remove(rtc, timer);
timer->node.expires = expires;
timer->period = period;
ret = rtc_timer_enqueue(rtc, timer);
mutex_unlock(&rtc->ops_lock);
return ret;
}
/* rtc_timer_cancel - Stops an rtc_timer
* @ rtc: rtc device to be used
* @ timer: timer being set
*
* Kernel interface to cancel an rtc_timer
*/
int rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer* timer)
{
int ret = 0;
mutex_lock(&rtc->ops_lock);
if (timer->enabled)
rtc_timer_remove(rtc, timer);
mutex_unlock(&rtc->ops_lock);
return ret;
}
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