rtc: move power of 2 periodic frequency check down into drivers

Move the power of 2 check on frequencies down into individual rtc drivers

This is to allow for non power of 2 real time clock periodic interrupts
such as those on the pxa27x to be found in the new pxa27x-rtc driver

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/interface.c

@@ -504,9 +504,6 @@ 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;

drivers/rtc/rtc-cmos.c

@@ -35,6 +35,7 @@
 #include <linux/spinlock.h>
 #include <linux/platform_device.h>
 #include <linux/mod_devicetable.h>
+#include <linux/log2.h>
 
 /* this is for "generic access to PC-style RTC" using CMOS_READ/CMOS_WRITE */
 #include <asm-generic/rtc.h>
@@ -384,6 +385,8 @@ static int cmos_irq_set_freq(struct device *dev, int freq)
 	if (!is_valid_irq(cmos->irq))
 		return -ENXIO;
 
+	if (!is_power_of_2(freq))
+		return -EINVAL;
 	/* 0 = no irqs; 1 = 2^15 Hz ... 15 = 2^0 Hz */
 	f = ffs(freq);
 	if (f-- > 16)

drivers/rtc/rtc-s3c.c

@@ -94,6 +94,9 @@ static int s3c_rtc_setfreq(struct device *dev, int freq)
 {
 	unsigned int tmp;
 
+	if (!is_power_of_2(freq))
+		return -EINVAL;
+
 	spin_lock_irq(&s3c_rtc_pie_lock);
 
 	tmp = readb(s3c_rtc_base + S3C2410_TICNT) & S3C2410_TICNT_ENABLE;

drivers/rtc/rtc-sh.c

@@ -24,6 +24,7 @@
 #include <linux/interrupt.h>
 #include <linux/spinlock.h>
 #include <linux/io.h>
+#include <linux/log2.h>
 #include <asm/rtc.h>
 
 #define DRV_NAME	"sh-rtc"
@@ -551,6 +552,8 @@ static int sh_rtc_irq_set_state(struct device *dev, int enabled)
 
 static int sh_rtc_irq_set_freq(struct device *dev, int freq)
 {
+	if (!is_power_of_2(freq))
+		return -EINVAL;
 	return sh_rtc_ioctl(dev, RTC_IRQP_SET, freq);
 }
 

drivers/rtc/rtc-vr41xx.c

@@ -27,6 +27,7 @@
 #include <linux/rtc.h>
 #include <linux/spinlock.h>
 #include <linux/types.h>
+#include <linux/log2.h>
 
 #include <asm/div64.h>
 #include <asm/io.h>
@@ -210,6 +211,8 @@ static int vr41xx_rtc_irq_set_freq(struct device *dev, int freq)
 {
 	unsigned long count;
 
+	if (!is_power_of_2(freq))
+		return -EINVAL;
 	count = RTC_FREQUENCY;
 	do_div(count, freq);