drivers/rtc/mxc: Convert get_alarm_or_time()/set_alarm_or_time() to use time64_t

We want to convert mxc_rtc_set_mmss() to use rtc_class_ops's
set_mmss64(), but it uses get_alarm_or_time()/set_alarm_or_time()
internal interfaces which are y2038 unsafe.

So here as a separate patch, it converts these two internal
interfaces of "mxc" to use safe time64_t to make some
preparations.

Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
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/1427945681-29972-13-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

drivers/rtc/rtc-mxc.c

@@ -106,7 +106,7 @@ static inline int is_imx1_rtc(struct rtc_plat_data *data)
  * This function is used to obtain the RTC time or the alarm value in
  * second.
  */
-static u32 get_alarm_or_time(struct device *dev, int time_alarm)
+static time64_t get_alarm_or_time(struct device *dev, int time_alarm)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
@@ -129,29 +129,28 @@ static u32 get_alarm_or_time(struct device *dev, int time_alarm)
 	hr = hr_min >> 8;
 	min = hr_min & 0xff;
 
-	return (((day * 24 + hr) * 60) + min) * 60 + sec;
+	return ((((time64_t)day * 24 + hr) * 60) + min) * 60 + sec;
 }
 
 /*
  * This function sets the RTC alarm value or the time value.
  */
-static void set_alarm_or_time(struct device *dev, int time_alarm, u32 time)
+static void set_alarm_or_time(struct device *dev, int time_alarm, time64_t time)
 {
-	u32 day, hr, min, sec, temp;
+	u32 tod, day, hr, min, sec, temp;
 	struct platform_device *pdev = to_platform_device(dev);
 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 	void __iomem *ioaddr = pdata->ioaddr;
 
-	day = time / 86400;
-	time -= day * 86400;
+	day = div_s64_rem(time, 86400, &tod);
 
 	/* time is within a day now */
-	hr = time / 3600;
-	time -= hr * 3600;
+	hr = tod / 3600;
+	tod -= hr * 3600;
 
 	/* time is within an hour now */
-	min = time / 60;
-	sec = time - min * 60;
+	min = tod / 60;
+	sec = tod - min * 60;
 
 	temp = (hr << 8) + min;
 
@@ -175,12 +174,12 @@ static void set_alarm_or_time(struct device *dev, int time_alarm, u32 time)
  */
 static void rtc_update_alarm(struct device *dev, struct rtc_time *alrm)
 {
-	unsigned long time;
+	time64_t time;
 	struct platform_device *pdev = to_platform_device(dev);
 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 	void __iomem *ioaddr = pdata->ioaddr;
 
-	rtc_tm_to_time(alrm, &time);
+	time = rtc_tm_to_time64(alrm);
 
 	/* clear all the interrupt status bits */
 	writew(readw(ioaddr + RTC_RTCISR), ioaddr + RTC_RTCISR);
@@ -272,14 +271,14 @@ static int mxc_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
  */
 static int mxc_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
-	u32 val;
+	time64_t val;
 
 	/* Avoid roll-over from reading the different registers */
 	do {
 		val = get_alarm_or_time(dev, MXC_RTC_TIME);
 	} while (val != get_alarm_or_time(dev, MXC_RTC_TIME));
 
-	rtc_time_to_tm(val, tm);
+	rtc_time64_to_tm(val, tm);
 
 	return 0;
 }
@@ -322,7 +321,7 @@ static int mxc_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
 	void __iomem *ioaddr = pdata->ioaddr;
 
-	rtc_time_to_tm(get_alarm_or_time(dev, MXC_RTC_ALARM), &alrm->time);
+	rtc_time64_to_tm(get_alarm_or_time(dev, MXC_RTC_ALARM), &alrm->time);
 	alrm->pending = ((readw(ioaddr + RTC_RTCISR) & RTC_ALM_BIT)) ? 1 : 0;
 
 	return 0;