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authorDavid Brownell <david-b@pacbell.net>2007-10-16 01:28:16 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-16 09:43:13 -0700
commit97144c67566241db46633727f2860e6428373fe4 (patch)
treeb3863ed198037668cb80df710678a6e249842654 /drivers/rtc
parentd691eb901e044065de10756ea78a5758d457c7fd (diff)
rtc_irq_set_freq() requires power-of-two and associated kerneldoc
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>
Diffstat (limited to 'drivers/rtc')
-rw-r--r--drivers/rtc/interface.c24
-rw-r--r--drivers/rtc/rtc-cmos.c8
2 files changed, 27 insertions, 5 deletions
diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index a43afa54f0d7..8adcab3c3653 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -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;
diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
index 5d760bb6c2cd..6d0c35397b49 100644
--- a/drivers/rtc/rtc-cmos.c
+++ b/drivers/rtc/rtc-cmos.c
@@ -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);