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;
 
 #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>
        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)
 
 {
        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;
 
 #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"
 
 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);
 }
 
 
 #include <linux/rtc.h>
 #include <linux/spinlock.h>
 #include <linux/types.h>
+#include <linux/log2.h>
 
 #include <asm/div64.h>
 #include <asm/io.h>
 {
        unsigned long count;
 
+       if (!is_power_of_2(freq))
+               return -EINVAL;
        count = RTC_FREQUENCY;
        do_div(count, freq);