linux/drivers/rtc/interface.c

391 lines
9.5 KiB
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/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);
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, 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);