drivers/rtc: Provide y2038 safe rtc_class_ops.set_mmss() replacement

Currently the rtc_class_op's set_mmss() function takes a 32-bit
second value (on 32-bit systems), which is problematic for dates
past y2038.

This patch provides a safe version named set_mmss64() using
y2038 safe time64_t.

After this patch, set_mmss() is deprecated and all its users
will be fixed to use set_mmss64(), it can be removed when having
no users.

Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
[jstultz: Add whitespace fix for checkpatch]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1427945681-29972-8-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

drivers/rtc/interface.c

@@ -72,7 +72,11 @@ int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm)
 		err = -ENODEV;
 	else if (rtc->ops->set_time)
 		err = rtc->ops->set_time(rtc->dev.parent, tm);
-	else if (rtc->ops->set_mmss) {
+	else if (rtc->ops->set_mmss64) {
+		time64_t secs64 = rtc_tm_to_time64(tm);
+
+		err = rtc->ops->set_mmss64(rtc->dev.parent, secs64);
+	} else if (rtc->ops->set_mmss) {
 		time64_t secs64 = rtc_tm_to_time64(tm);
 		err = rtc->ops->set_mmss(rtc->dev.parent, secs64);
 	} else
@@ -96,6 +100,8 @@ int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs)
 
 	if (!rtc->ops)
 		err = -ENODEV;
+	else if (rtc->ops->set_mmss64)
+		err = rtc->ops->set_mmss64(rtc->dev.parent, secs);
 	else if (rtc->ops->set_mmss)
 		err = rtc->ops->set_mmss(rtc->dev.parent, secs);
 	else if (rtc->ops->read_time && rtc->ops->set_time) {

drivers/rtc/systohc.c

@@ -35,7 +35,10 @@ int rtc_set_ntp_time(struct timespec64 now)
 	if (rtc) {
 		/* rtc_hctosys exclusively uses UTC, so we call set_time here,
 		 * not set_mmss. */
-		if (rtc->ops && (rtc->ops->set_time || rtc->ops->set_mmss))
+		if (rtc->ops &&
+		    (rtc->ops->set_time ||
+		     rtc->ops->set_mmss64 ||
+		     rtc->ops->set_mmss))
 			err = rtc_set_time(rtc, &tm);
 		rtc_class_close(rtc);
 	}

include/linux/rtc.h

@@ -77,6 +77,7 @@ struct rtc_class_ops {
 	int (*read_alarm)(struct device *, struct rtc_wkalrm *);
 	int (*set_alarm)(struct device *, struct rtc_wkalrm *);
 	int (*proc)(struct device *, struct seq_file *);
+	int (*set_mmss64)(struct device *, time64_t secs);
 	int (*set_mmss)(struct device *, unsigned long secs);
 	int (*read_callback)(struct device *, int data);
 	int (*alarm_irq_enable)(struct device *, unsigned int enabled);