rtc-dev: return -ENOTTY in ioctl if irq_set_freq is not implemented by driver

Signed-off-by: NHans-Christian Egtvedt <hcegtvedt@atmel.com>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: David Brownell <david-b@pacbell.net>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/rtc-dev.c

@@ -341,6 +341,8 @@ static int rtc_dev_ioctl(struct inode *inode, struct file *file,
 	case RTC_IRQP_READ:
 		if (ops->irq_set_freq)
 			err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
+		else
+			err = -ENOTTY;
 		break;
 
 	case RTC_IRQP_SET: