[PATCH v1 1/3] rtc: da9052: Add extra reads with timeouts to avoid returning partially updated values

[PATCH v1 1/3] rtc: da9052: Add extra reads with timeouts to avoid returning partially updated values

[Adam Ward]

The RTC is in a different clock domain so a quick read after write
can retrieve a mangled value of the old/new values

Signed-off-by: Adam Ward <adam.ward.opensource@diasemi.com>
Tested-by: Adam Ward <adam.ward.opensource@diasemi.com>
---
 drivers/rtc/rtc-da9052.c | 87 ++++++++++++++++++++++++++++++++++++------------
 1 file changed, 66 insertions(+), 21 deletions(-)

diff --git a/drivers/rtc/rtc-da9052.c b/drivers/rtc/rtc-da9052.c
index 613c43b..ead02fa 100644
--- a/drivers/rtc/rtc-da9052.c
+++ b/drivers/rtc/rtc-da9052.c
@@ -16,6 +16,7 @@
 #include <linux/platform_device.h>
 #include <linux/rtc.h>
 #include <linux/err.h>
+#include <linux/delay.h>

 #include <linux/mfd/da9052/da9052.h>
 #include <linux/mfd/da9052/reg.h>
@@ -23,6 +24,8 @@
 #define rtc_err(rtc, fmt, ...) \
 		dev_err(rtc->da9052->dev, "%s: " fmt, __func__, ##__VA_ARGS__)

+#define DA9052_GET_TIME_RETRIES 5
+
 struct da9052_rtc {
 	struct rtc_device *rtc;
 	struct da9052 *da9052;
@@ -58,22 +61,43 @@ static irqreturn_t da9052_rtc_irq(int irq, void *data)
 static int da9052_read_alarm(struct da9052_rtc *rtc, struct rtc_time *rtc_tm)
 {
 	int ret;
-	uint8_t v[5];
+	uint8_t v[2][5];
+	int idx = 1;
+	int timeout = DA9052_GET_TIME_RETRIES;

-	ret = da9052_group_read(rtc->da9052, DA9052_ALARM_MI_REG, 5, v);
-	if (ret != 0) {
+	ret = da9052_group_read(rtc->da9052, DA9052_ALARM_MI_REG, 5, &v[0][0]);
+	if (ret) {
 		rtc_err(rtc, "Failed to group read ALM: %d\n", ret);
 		return ret;
 	}

-	rtc_tm->tm_year = (v[4] & DA9052_RTC_YEAR) + 100;
-	rtc_tm->tm_mon  = (v[3] & DA9052_RTC_MONTH) - 1;
-	rtc_tm->tm_mday = v[2] & DA9052_RTC_DAY;
-	rtc_tm->tm_hour = v[1] & DA9052_RTC_HOUR;
-	rtc_tm->tm_min  = v[0] & DA9052_RTC_MIN;
+	do {
+		ret = da9052_group_read(rtc->da9052,
+					DA9052_ALARM_MI_REG, 5, &v[idx][0]);
+		if (ret) {
+			rtc_err(rtc, "Failed to group read ALM: %d\n", ret);
+			return ret;
+		}

-	ret = rtc_valid_tm(rtc_tm);
-	return ret;
+		if (memcmp(&v[0][0], &v[1][0], 5) == 0) {
+			rtc_tm->tm_year = (v[0][4] & DA9052_RTC_YEAR) + 100;
+			rtc_tm->tm_mon  = (v[0][3] & DA9052_RTC_MONTH) - 1;
+			rtc_tm->tm_mday = v[0][2] & DA9052_RTC_DAY;
+			rtc_tm->tm_hour = v[0][1] & DA9052_RTC_HOUR;
+			rtc_tm->tm_min  = v[0][0] & DA9052_RTC_MIN;
+
+			ret = rtc_valid_tm(rtc_tm);
+			return ret;
+		}
+
+		idx = (1-idx);
+		msleep(20);
+
+	} while (timeout--);
+
+	rtc_err(rtc, "Timed out reading alarm time\n");
+
+	return -EIO;
 }

 static int da9052_set_alarm(struct da9052_rtc *rtc, struct rtc_time *rtc_tm)
@@ -135,24 +159,45 @@ static int da9052_rtc_get_alarm_status(struct da9052_rtc *rtc)
 static int da9052_rtc_read_time(struct device *dev, struct rtc_time *rtc_tm)
 {
 	struct da9052_rtc *rtc = dev_get_drvdata(dev);
-	uint8_t v[6];
 	int ret;
+	uint8_t v[2][6];
+	int idx = 1;
+	int timeout = DA9052_GET_TIME_RETRIES;

-	ret = da9052_group_read(rtc->da9052, DA9052_COUNT_S_REG, 6, v);
-	if (ret < 0) {
+	ret = da9052_group_read(rtc->da9052, DA9052_COUNT_S_REG, 6, &v[0][0]);
+	if (ret) {
 		rtc_err(rtc, "Failed to read RTC time : %d\n", ret);
 		return ret;
 	}

-	rtc_tm->tm_year = (v[5] & DA9052_RTC_YEAR) + 100;
-	rtc_tm->tm_mon  = (v[4] & DA9052_RTC_MONTH) - 1;
-	rtc_tm->tm_mday = v[3] & DA9052_RTC_DAY;
-	rtc_tm->tm_hour = v[2] & DA9052_RTC_HOUR;
-	rtc_tm->tm_min  = v[1] & DA9052_RTC_MIN;
-	rtc_tm->tm_sec  = v[0] & DA9052_RTC_SEC;
+	do {
+		ret = da9052_group_read(rtc->da9052,
+					DA9052_COUNT_S_REG, 6, &v[idx][0]);
+		if (ret) {
+			rtc_err(rtc, "Failed to read RTC time : %d\n", ret);
+			return ret;
+		}

-	ret = rtc_valid_tm(rtc_tm);
-	return ret;
+		if (memcmp(&v[0][0], &v[1][0], 6) == 0) {
+			rtc_tm->tm_year = (v[0][5] & DA9052_RTC_YEAR) + 100;
+			rtc_tm->tm_mon  = (v[0][4] & DA9052_RTC_MONTH) - 1;
+			rtc_tm->tm_mday = v[0][3] & DA9052_RTC_DAY;
+			rtc_tm->tm_hour = v[0][2] & DA9052_RTC_HOUR;
+			rtc_tm->tm_min  = v[0][1] & DA9052_RTC_MIN;
+			rtc_tm->tm_sec  = v[0][0] & DA9052_RTC_SEC;
+
+			ret = rtc_valid_tm(rtc_tm);
+			return ret;
+		}
+
+		idx = (1-idx);
+		msleep(20);
+
+	} while (timeout--);
+
+	rtc_err(rtc, "Timed out reading time\n");
+
+	return -EIO;
 }

 static int da9052_rtc_set_time(struct device *dev, struct rtc_time *tm)
-- 
end-of-patch for rtc: da9052: Corrections to access, validation and capability

[PATCH v1 3/3] rtc: da9052: Register ability of alarm to wake device from suspend

[Adam Ward]

Signed-off-by: Adam Ward <adam.ward.opensource@diasemi.com>
Tested-by: Adam Ward <adam.ward.opensource@diasemi.com>
---
 drivers/rtc/rtc-da9052.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/rtc/rtc-da9052.c b/drivers/rtc/rtc-da9052.c
index acc3e5a..1ba4371 100644
--- a/drivers/rtc/rtc-da9052.c
+++ b/drivers/rtc/rtc-da9052.c
@@ -309,6 +309,8 @@ static int da9052_rtc_probe(struct platform_device *pdev)
 		return ret;
 	}

+	device_init_wakeup(&pdev->dev, true);
+
 	rtc->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
 				       &da9052_rtc_ops, THIS_MODULE);
 	return PTR_ERR_OR_ZERO(rtc->rtc);
-- 
end-of-patch for rtc: da9052: Corrections to access, validation and capability

[PATCH v1 2/3] rtc: da9052: Add constraints to set valid year

[Adam Ward]

Signed-off-by: Adam Ward <adam.ward.opensource@diasemi.com>
Tested-by: Adam Ward <adam.ward.opensource@diasemi.com>
---
 drivers/rtc/rtc-da9052.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/rtc/rtc-da9052.c b/drivers/rtc/rtc-da9052.c
index ead02fa..acc3e5a 100644
--- a/drivers/rtc/rtc-da9052.c
+++ b/drivers/rtc/rtc-da9052.c
@@ -206,6 +206,10 @@ static int da9052_rtc_set_time(struct device *dev, struct rtc_time *tm)
 	uint8_t v[6];
 	int ret;

+	/* DA9052 only has 6 bits for year - to represent 2000-2063 */
+	if ((tm->tm_year < 100) || (tm->tm_year > 163))
+		return -EINVAL;
+
 	rtc = dev_get_drvdata(dev);

 	v[0] = tm->tm_sec;
@@ -243,6 +247,10 @@ static int da9052_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 	struct rtc_time *tm = &alrm->time;
 	struct da9052_rtc *rtc = dev_get_drvdata(dev);

+	/* DA9052 only has 6 bits for year - to represent 2000-2063 */
+	if ((tm->tm_year < 100) || (tm->tm_year > 163))
+		return -EINVAL;
+
 	ret = da9052_rtc_enable_alarm(rtc, 0);
 	if (ret < 0)
 		return ret;
-- 
end-of-patch for rtc: da9052: Corrections to access, validation and capability

[PATCH v1 0/3] rtc: da9052: Corrections to access, validation and capability

[Adam Ward]

Hi,

This patch set is based on mainline v4.0-rc2.

It makes corrections to restrict the year setting to the range defined
for the device to support. It also prevents erroneous values being returned, as
was discovered possible when reading a time immediately after setting it.

And lastly, it enables the wake-from-suspend capability.

Best regards,
Adam

Adam Ward (3):
  rtc: da9052: Add extra reads with timeouts to avoid returning
    partially updated values
  rtc: da9052: Add constraints to set valid year
  rtc: da9052: Register ability of alarm to wake device from suspend

 drivers/rtc/rtc-da9052.c | 97 +++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 76 insertions(+), 21 deletions(-)

-- 
end-of-patch for rtc: da9052: Corrections to access, validation and capability