[RFC PATCH 4/4] rtc/imxdi: Update driver to address time issues

[Xunlei Pang]

The rtc/imxdi rtc driver has a number of y2038/y2106 issues, the worst
one is its hardware only supports 32-bit time.

This patch resolves them based on our foregoing efforts:
- Replace rtc_time_to_tm() with rtc_hw32_to_time64()/rtc_time64_to_tm()
- Replace rtc_tm_to_time() with rtc_tm_to_time64()/rtc_time64_to_hw32()
- Use rtc_time64_to_hw32() to handle dryice_rtc_set_mmss()

After this patch, the drivers should not have any remaining y2038/y2106
issues.

Cc: John Stultz <john.stultz@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd.bergmann@xxxxxxxxxx>
Signed-off-by: Xunlei Pang <pang.xunlei@xxxxxxxxxx>
---
 drivers/rtc/rtc-imxdi.c |   41 +++++++++++++++++++++--------------------
 1 file changed, 21 insertions(+), 20 deletions(-)

diff --git a/drivers/rtc/rtc-imxdi.c b/drivers/rtc/rtc-imxdi.c
index 34d76b2..015290f 100644
--- a/drivers/rtc/rtc-imxdi.c
+++ b/drivers/rtc/rtc-imxdi.c
@@ -197,10 +197,10 @@ out:
 static int dryice_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
 	struct imxdi_dev *imxdi = dev_get_drvdata(dev);
-	unsigned long now;
+	time64_t now;
 
-	now = __raw_readl(imxdi->ioaddr + DTCMR);
-	rtc_time_to_tm(now, tm);
+	now = rtc_hw32_to_time64(__raw_readl(imxdi->ioaddr + DTCMR));
+	rtc_time64_to_tm(now, tm);
 
 	return 0;
 }
@@ -213,17 +213,16 @@ static int dryice_rtc_set_mmss(struct device *dev, time64_t secs)
 {
 	struct imxdi_dev *imxdi = dev_get_drvdata(dev);
 	int rc;
+	u32 hwtime;
+
+	rc = rtc_time64_to_hw32(secs, &hwtime);
+	if (rc < 0)
+		return rc;
 
 	/* zero the fractional part first */
 	rc = di_write_wait(imxdi, 0, DTCLR);
 	if (rc == 0)
-		/*
-		 * y2106 issue:
-		 *   On 32bit systems the time64_t secs value gets cast to
-		 *   a 32bit long, and thus we can only write a maximum value
-		 *   of y2016
-		 */
-		rc = di_write_wait(imxdi, secs, DTCMR);
+		rc = di_write_wait(imxdi, hwtime, DTCMR);
 
 	return rc;
 }
@@ -248,10 +247,10 @@ static int dryice_rtc_alarm_irq_enable(struct device *dev,
 static int dryice_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	struct imxdi_dev *imxdi = dev_get_drvdata(dev);
-	u32 dcamr;
+	time64_t alarm_time;
 
-	dcamr = __raw_readl(imxdi->ioaddr + DCAMR);
-	rtc_time_to_tm(dcamr, &alarm->time);
+	alarm_time = rtc_hw32_to_time64(__raw_readl(imxdi->ioaddr + DCAMR));
+	rtc_time64_to_tm(alarm_time, &alarm->time);
 
 	/* alarm is enabled if the interrupt is enabled */
 	alarm->enabled = (__raw_readl(imxdi->ioaddr + DIER) & DIER_CAIE) != 0;
@@ -273,21 +272,23 @@ static int dryice_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 static int dryice_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 {
 	struct imxdi_dev *imxdi = dev_get_drvdata(dev);
-	unsigned long now;
-	unsigned long alarm_time;
+	time64_t alarm_time, now;
+	u32 alarm_hwtime;
 	int rc;
 
-	rc = rtc_tm_to_time(&alarm->time, &alarm_time);
-	if (rc)
-		return rc;
+	alarm_time = rtc_tm_to_time64(&alarm->time);
+	now = rtc_hw32_to_time64(__raw_readl(imxdi->ioaddr + DTCMR));
 
 	/* don't allow setting alarm in the past */
-	now = __raw_readl(imxdi->ioaddr + DTCMR);
 	if (alarm_time < now)
 		return -EINVAL;
 
+	rc = rtc_time64_to_hw32(alarm_time, &alarm_hwtime);
+	if (rc < 0)
+		return rc;
+
 	/* write the new alarm time */
-	rc = di_write_wait(imxdi, (u32)alarm_time, DCAMR);
+	rc = di_write_wait(imxdi, alarm_hwtime, DCAMR);
 	if (rc)
 		return rc;
 
-- 
1.7.9.5

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