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linux-next/drivers/rtc/interface.c
David Brownell d728b1e69f [PATCH] rtc class locking bugfixes 
I got a lockdep warning when running "rtctest" so I though it'd be good
to see what was up.

 - The warning was for rtc->irq_task_lock, gotten from rtc_update_irq()
   by irq handlerss ... but in a handful of other cases, grabbed without
   blocking IRQs.

 - Some callers to rtc_update_irq() were not ensuring IRQs were blocked,
   yet the routine expects that; make sure all callers block IRQs.

It would appear that RTC API tests haven't been part of anyone's kernel
regression test suite recently, at least not with lockdep running.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-11-25 13:28:33 -08:00

276 lines
6.4 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>
int rtc_read_time(struct class_device *class_dev, struct rtc_time *tm)
{
int err;
struct rtc_device *rtc = to_rtc_device(class_dev);
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(class_dev->dev, tm);
}
mutex_unlock(&rtc->ops_lock);
return err;
}
EXPORT_SYMBOL_GPL(rtc_read_time);
int rtc_set_time(struct class_device *class_dev, struct rtc_time *tm)
{
int err;
struct rtc_device *rtc = to_rtc_device(class_dev);
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(class_dev->dev, tm);
mutex_unlock(&rtc->ops_lock);
return err;
}
EXPORT_SYMBOL_GPL(rtc_set_time);
int rtc_set_mmss(struct class_device *class_dev, unsigned long secs)
{
int err;
struct rtc_device *rtc = to_rtc_device(class_dev);
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(class_dev->dev, secs);
else if (rtc->ops->read_time && rtc->ops->set_time) {
struct rtc_time new, old;
err = rtc->ops->read_time(class_dev->dev, &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(class_dev->dev, &new);
}
}
else
err = -EINVAL;
mutex_unlock(&rtc->ops_lock);
return err;
}
EXPORT_SYMBOL_GPL(rtc_set_mmss);
int rtc_read_alarm(struct class_device *class_dev, struct rtc_wkalrm *alarm)
{
int err;
struct rtc_device *rtc = to_rtc_device(class_dev);
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(class_dev->dev, alarm);
}
mutex_unlock(&rtc->ops_lock);
return err;
}
EXPORT_SYMBOL_GPL(rtc_read_alarm);
int rtc_set_alarm(struct class_device *class_dev, struct rtc_wkalrm *alarm)
{
int err;
struct rtc_device *rtc = to_rtc_device(class_dev);
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(class_dev->dev, 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
* @class_dev: the rtc's class 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 class_device *class_dev,
unsigned long num, unsigned long events)
{
struct rtc_device *rtc = to_rtc_device(class_dev);
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 class_device *rtc_class_open(char *name)
{
struct class_device *class_dev = NULL,
*class_dev_tmp;
down(&rtc_class->sem);
list_for_each_entry(class_dev_tmp, &rtc_class->children, node) {
if (strncmp(class_dev_tmp->class_id, name, BUS_ID_SIZE) == 0) {
class_dev = class_dev_tmp;
break;
}
}
if (class_dev) {
if (!try_module_get(to_rtc_device(class_dev)->owner))
class_dev = NULL;
}
up(&rtc_class->sem);
return class_dev;
}
EXPORT_SYMBOL_GPL(rtc_class_open);
void rtc_class_close(struct class_device *class_dev)
{
module_put(to_rtc_device(class_dev)->owner);
}
EXPORT_SYMBOL_GPL(rtc_class_close);
int rtc_irq_register(struct class_device *class_dev, struct rtc_task *task)
{
int retval = -EBUSY;
struct rtc_device *rtc = to_rtc_device(class_dev);
if (task == NULL || task->func == NULL)
return -EINVAL;
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);
return retval;
}
EXPORT_SYMBOL_GPL(rtc_irq_register);
void rtc_irq_unregister(struct class_device *class_dev, struct rtc_task *task)
{
struct rtc_device *rtc = to_rtc_device(class_dev);
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);
int rtc_irq_set_state(struct class_device *class_dev, struct rtc_task *task, int enabled)
{
int err = 0;
unsigned long flags;
struct rtc_device *rtc = to_rtc_device(class_dev);
if (rtc->ops->irq_set_state == NULL)
return -ENXIO;
spin_lock_irqsave(&rtc->irq_task_lock, flags);
if (rtc->irq_task != task)
err = -ENXIO;
spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
if (err == 0)
err = rtc->ops->irq_set_state(class_dev->dev, enabled);
return err;
}
EXPORT_SYMBOL_GPL(rtc_irq_set_state);
int rtc_irq_set_freq(struct class_device *class_dev, struct rtc_task *task, int freq)
{
int err = 0;
unsigned long flags;
struct rtc_device *rtc = to_rtc_device(class_dev);
if (rtc->ops->irq_set_freq == NULL)
return -ENXIO;
spin_lock_irqsave(&rtc->irq_task_lock, flags);
if (rtc->irq_task != task)
err = -ENXIO;
spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
if (err == 0) {
err = rtc->ops->irq_set_freq(class_dev->dev, freq);
if (err == 0)
rtc->irq_freq = freq;
}
return err;
}
EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
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