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rtc_irq_set_freq() requires power-of-two and associated kerneldoc

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RTC periodic IRQs are only defined to work for 2^N Hz values.  This patch
moves that validity check into the infrastructure, so drivers don't need to
check it; and adds kerneldoc for the two interface functions related to
periodic IRQs.  (One of which was quite mysterious until its first use was
recently checked in!)

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Brownell 2007-10-16 01:28:16 -07:00 committed by Linus Torvalds
parent d691eb901e
commit 97144c6756
2 changed files with 27 additions and 5 deletions
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24
drivers/rtc/interface.c
View File

@ -12,6 +12,7 @@
*/
#include <linux/rtc.h>
#include <linux/log2.h>
int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
{
@ -236,6 +237,16 @@ void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
}
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;
@ -258,6 +269,16 @@ int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled
}
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;
@ -266,6 +287,9 @@ int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
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;

8
drivers/rtc/rtc-cmos.c
View File

@ -246,11 +246,9 @@ static int cmos_irq_set_freq(struct device *dev, int freq)
/* 0 = no irqs; 1 = 2^15 Hz ... 15 = 2^0 Hz */
f = ffs(freq);
if (f != 0) {
if (f-- > 16 || freq != (1 << f))
return -EINVAL;
f = 16 - f;
}
if (f-- > 16)
return -EINVAL;
f = 16 - f;
spin_lock_irqsave(&rtc_lock, flags);
CMOS_WRITE(RTC_REF_CLCK_32KHZ | f, RTC_FREQ_SELECT);