#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);