[PATCH 01/10] rtc: add a timestamp for year 0

[PATCH 01/10] rtc: add a timestamp for year 0

[Alexandre Belloni]

A few RTCs handle dates from year 0 to year 9999. Add a timestamp even if
years before 1970 will probably never be used.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 include/linux/rtc.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index df666cf29ef1..2680f9b2b119 100644
--- a/include/linux/rtc.h
+++ b/include/linux/rtc.h
@@ -160,6 +160,7 @@ struct rtc_device {
 #define to_rtc_device(d) container_of(d, struct rtc_device, dev)
 
 /* useful timestamps */
+#define RTC_TIMESTAMP_BEGIN_0000	-62167219200ULL /* 0000-01-01 00:00:00 */
 #define RTC_TIMESTAMP_BEGIN_1900	-2208988800LL /* 1900-01-01 00:00:00 */
 #define RTC_TIMESTAMP_BEGIN_2000	946684800LL /* 2000-01-01 00:00:00 */
 #define RTC_TIMESTAMP_END_2063		2966371199LL /* 2063-12-31 23:59:59 */
-- 
2.21.0

[PATCH 02/10] rtc: ds1347: remove verbose messages

[Alexandre Belloni]

Printing debugging (and opaque) information is not useful and only clutters
the boot log. Remove those messages.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 drivers/rtc/rtc-ds1347.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/rtc/rtc-ds1347.c b/drivers/rtc/rtc-ds1347.c
index d392a7bfdd1c..ab5533c7f99d 100644
--- a/drivers/rtc/rtc-ds1347.c
+++ b/drivers/rtc/rtc-ds1347.c
@@ -141,13 +141,6 @@ static int ds1347_probe(struct spi_device *spi)
 	data = data & 0x1B;
 	regmap_write(map, DS1347_STATUS_REG, data);
 
-	/* display the settings */
-	regmap_read(map, DS1347_CONTROL_REG, &data);
-	dev_info(&spi->dev, "DS1347 RTC CTRL Reg = 0x%02x\n", data);
-
-	regmap_read(map, DS1347_STATUS_REG, &data);
-	dev_info(&spi->dev, "DS1347 RTC Status Reg = 0x%02x\n", data);
-
 	rtc = devm_rtc_device_register(&spi->dev, "ds1347",
 				&ds1347_rtc_ops, THIS_MODULE);
 
-- 
2.21.0

[PATCH 03/10] rtc: ds1347: remove useless read

[Alexandre Belloni]

DS1347_SECONDS_REG is read at probe time but the value is simply discarded.
Remove that useless read.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 drivers/rtc/rtc-ds1347.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/rtc/rtc-ds1347.c b/drivers/rtc/rtc-ds1347.c
index ab5533c7f99d..013c5df13765 100644
--- a/drivers/rtc/rtc-ds1347.c
+++ b/drivers/rtc/rtc-ds1347.c
@@ -102,7 +102,6 @@ static int ds1347_probe(struct spi_device *spi)
 	struct regmap_config config;
 	struct regmap *map;
 	unsigned int data;
-	int res;
 
 	memset(&config, 0, sizeof(config));
 	config.reg_bits = 8;
@@ -125,11 +124,6 @@ static int ds1347_probe(struct spi_device *spi)
 
 	spi_set_drvdata(spi, map);
 
-	/* RTC Settings */
-	res = regmap_read(map, DS1347_SECONDS_REG, &data);
-	if (res)
-		return res;
-
 	/* Disable the write protect of rtc */
 	regmap_read(map, DS1347_CONTROL_REG, &data);
 	data = data & ~(1<<7);
-- 
2.21.0

[PATCH 04/10] rtc: ds1347: simplify getting .driver_data

[Alexandre Belloni]

Get 'driver_data' from 'struct device' directly. Going via spi_device is an
unnecessary step.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 drivers/rtc/rtc-ds1347.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/rtc/rtc-ds1347.c b/drivers/rtc/rtc-ds1347.c
index 013c5df13765..06abf0b47e16 100644
--- a/drivers/rtc/rtc-ds1347.c
+++ b/drivers/rtc/rtc-ds1347.c
@@ -43,13 +43,10 @@ static const struct regmap_access_table ds1347_access_table = {
 
 static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
 {
-	struct spi_device *spi = to_spi_device(dev);
-	struct regmap *map;
+	struct regmap *map = dev_get_drvdata(dev);
 	int err;
 	unsigned char buf[8];
 
-	map = spi_get_drvdata(spi);
-
 	err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8);
 	if (err)
 		return err;
@@ -67,12 +64,9 @@ static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
 
 static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
 {
-	struct spi_device *spi = to_spi_device(dev);
-	struct regmap *map;
+	struct regmap *map = dev_get_drvdata(dev);
 	unsigned char buf[8];
 
-	map = spi_get_drvdata(spi);
-
 	buf[0] = bin2bcd(dt->tm_sec);
 	buf[1] = bin2bcd(dt->tm_min);
 	buf[2] = (bin2bcd(dt->tm_hour) & 0x3F);
-- 
2.21.0

[PATCH 05/10] rtc: ds1347: mask ALM OUT when reading time

[Alexandre Belloni]

Bit 7 of the minutes registers is ALM OUT. It indicates an alarm fired.
Mask it out when reading the time.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 drivers/rtc/rtc-ds1347.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/rtc/rtc-ds1347.c b/drivers/rtc/rtc-ds1347.c
index 06abf0b47e16..763eb60e5e8f 100644
--- a/drivers/rtc/rtc-ds1347.c
+++ b/drivers/rtc/rtc-ds1347.c
@@ -52,7 +52,7 @@ static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
 		return err;
 
 	dt->tm_sec = bcd2bin(buf[0]);
-	dt->tm_min = bcd2bin(buf[1]);
+	dt->tm_min = bcd2bin(buf[1] & 0x7f);
 	dt->tm_hour = bcd2bin(buf[2] & 0x3F);
 	dt->tm_mday = bcd2bin(buf[3]);
 	dt->tm_mon = bcd2bin(buf[4]) - 1;
-- 
2.21.0

[PATCH 06/10] rtc: ds1347: convert to devm_rtc_allocate_device

[Alexandre Belloni]

This allows further improvement of the driver.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 drivers/rtc/rtc-ds1347.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/rtc/rtc-ds1347.c b/drivers/rtc/rtc-ds1347.c
index 763eb60e5e8f..75c522c8ab26 100644
--- a/drivers/rtc/rtc-ds1347.c
+++ b/drivers/rtc/rtc-ds1347.c
@@ -129,13 +129,13 @@ static int ds1347_probe(struct spi_device *spi)
 	data = data & 0x1B;
 	regmap_write(map, DS1347_STATUS_REG, data);
 
-	rtc = devm_rtc_device_register(&spi->dev, "ds1347",
-				&ds1347_rtc_ops, THIS_MODULE);
-
+	rtc = devm_rtc_allocate_device(&spi->dev);
 	if (IS_ERR(rtc))
 		return PTR_ERR(rtc);
 
-	return 0;
+	rtc->ops = &ds1347_rtc_ops;
+
+	return rtc_register_device(rtc);
 }
 
 static struct spi_driver ds1347_driver = {
-- 
2.21.0

[PATCH 07/10] rtc: ds1347: set range

[Alexandre Belloni]

The DS1347 handle dates from year 0000 to 9999. Leap years are claimed to
be handled correctly in the datasheet.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 drivers/rtc/rtc-ds1347.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/rtc/rtc-ds1347.c b/drivers/rtc/rtc-ds1347.c
index 75c522c8ab26..22a75b01f1ac 100644
--- a/drivers/rtc/rtc-ds1347.c
+++ b/drivers/rtc/rtc-ds1347.c
@@ -134,6 +134,8 @@ static int ds1347_probe(struct spi_device *spi)
 		return PTR_ERR(rtc);
 
 	rtc->ops = &ds1347_rtc_ops;
+	rtc->range_min = RTC_TIMESTAMP_BEGIN_0000;
+	rtc->range_max = RTC_TIMESTAMP_END_9999;
 
 	return rtc_register_device(rtc);
 }
-- 
2.21.0

[PATCH 08/10] rtc: ds1347: properly handle oscillator failures

[Alexandre Belloni]

The comment in the probe function stating that it disables oscillator stop
detection and glitch filtering is incorrect as it sets bits 3 and 4 while
it should be setting 5 and 6 to achieve that. Then, it is safe to assume
that the oscillator failure detection is actually enabled.

Properly handle oscillator failures by returning -EINVAL when the time and
date are know to be incorrect and reset the flag when the time is set.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 drivers/rtc/rtc-ds1347.c | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/drivers/rtc/rtc-ds1347.c b/drivers/rtc/rtc-ds1347.c
index 22a75b01f1ac..eeaf43586bce 100644
--- a/drivers/rtc/rtc-ds1347.c
+++ b/drivers/rtc/rtc-ds1347.c
@@ -29,6 +29,9 @@
 #define DS1347_STATUS_REG	0x17
 #define DS1347_CLOCK_BURST	0x3F
 
+#define DS1347_NEOSC_BIT	BIT(7)
+#define DS1347_OSF_BIT		BIT(2)
+
 static const struct regmap_range ds1347_ranges[] = {
 	{
 		.range_min = DS1347_SECONDS_REG,
@@ -44,9 +47,17 @@ static const struct regmap_access_table ds1347_access_table = {
 static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
 {
 	struct regmap *map = dev_get_drvdata(dev);
+	unsigned int status;
 	int err;
 	unsigned char buf[8];
 
+	err = regmap_read(map, DS1347_STATUS_REG, &status);
+	if (err)
+		return err;
+
+	if (status & DS1347_OSF_BIT)
+		return -EINVAL;
+
 	err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8);
 	if (err)
 		return err;
@@ -66,6 +77,12 @@ static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
 {
 	struct regmap *map = dev_get_drvdata(dev);
 	unsigned char buf[8];
+	int err;
+
+	err = regmap_update_bits(map, DS1347_STATUS_REG,
+				 DS1347_NEOSC_BIT, DS1347_NEOSC_BIT);
+	if (err)
+		return err;
 
 	buf[0] = bin2bcd(dt->tm_sec);
 	buf[1] = bin2bcd(dt->tm_min);
@@ -82,7 +99,12 @@ static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
 	buf[7] = bin2bcd(0x00);
 
 	/* write the rtc settings */
-	return regmap_bulk_write(map, DS1347_CLOCK_BURST, buf, 8);
+	err = regmap_bulk_write(map, DS1347_CLOCK_BURST, buf, 8);
+	if (err)
+		return err;
+
+	return regmap_update_bits(map, DS1347_STATUS_REG,
+				  DS1347_NEOSC_BIT | DS1347_OSF_BIT, 0);
 }
 
 static const struct rtc_class_ops ds1347_rtc_ops = {
@@ -123,12 +145,6 @@ static int ds1347_probe(struct spi_device *spi)
 	data = data & ~(1<<7);
 	regmap_write(map, DS1347_CONTROL_REG, data);
 
-	/* Enable the oscillator , disable the oscillator stop flag,
-	 and glitch filter to reduce current consumption */
-	regmap_read(map, DS1347_STATUS_REG, &data);
-	data = data & 0x1B;
-	regmap_write(map, DS1347_STATUS_REG, data);
-
 	rtc = devm_rtc_allocate_device(&spi->dev);
 	if (IS_ERR(rtc))
 		return PTR_ERR(rtc);
-- 
2.21.0

[PATCH 09/10] rtc: ds1347: use regmap_update_bits

[Alexandre Belloni]

Use regmap_update_bits instead of open coding. Also add proper error
handling.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 drivers/rtc/rtc-ds1347.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/rtc/rtc-ds1347.c b/drivers/rtc/rtc-ds1347.c
index eeaf43586bce..a49ce9991916 100644
--- a/drivers/rtc/rtc-ds1347.c
+++ b/drivers/rtc/rtc-ds1347.c
@@ -29,6 +29,8 @@
 #define DS1347_STATUS_REG	0x17
 #define DS1347_CLOCK_BURST	0x3F
 
+#define DS1347_WP_BIT		BIT(7)
+
 #define DS1347_NEOSC_BIT	BIT(7)
 #define DS1347_OSF_BIT		BIT(2)
 
@@ -117,7 +119,7 @@ static int ds1347_probe(struct spi_device *spi)
 	struct rtc_device *rtc;
 	struct regmap_config config;
 	struct regmap *map;
-	unsigned int data;
+	int err;
 
 	memset(&config, 0, sizeof(config));
 	config.reg_bits = 8;
@@ -141,9 +143,9 @@ static int ds1347_probe(struct spi_device *spi)
 	spi_set_drvdata(spi, map);
 
 	/* Disable the write protect of rtc */
-	regmap_read(map, DS1347_CONTROL_REG, &data);
-	data = data & ~(1<<7);
-	regmap_write(map, DS1347_CONTROL_REG, data);
+	err = regmap_update_bits(map, DS1347_CONTROL_REG, DS1347_WP_BIT, 0);
+	if (err)
+		return err;
 
 	rtc = devm_rtc_allocate_device(&spi->dev);
 	if (IS_ERR(rtc))
-- 
2.21.0

[PATCH 10/10] rtc: ds1347: handle century register

[Alexandre Belloni]

The DS1347 can handle years from 0 to 9999, add century register support.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 drivers/rtc/rtc-ds1347.c | 37 ++++++++++++++++++++++++-------------
 1 file changed, 24 insertions(+), 13 deletions(-)

diff --git a/drivers/rtc/rtc-ds1347.c b/drivers/rtc/rtc-ds1347.c
index a49ce9991916..7025cf3fb9f8 100644
--- a/drivers/rtc/rtc-ds1347.c
+++ b/drivers/rtc/rtc-ds1347.c
@@ -26,6 +26,7 @@
 #define DS1347_DAY_REG		0x0B
 #define DS1347_YEAR_REG		0x0D
 #define DS1347_CONTROL_REG	0x0F
+#define DS1347_CENTURY_REG	0x13
 #define DS1347_STATUS_REG	0x17
 #define DS1347_CLOCK_BURST	0x3F
 
@@ -49,9 +50,9 @@ static const struct regmap_access_table ds1347_access_table = {
 static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
 {
 	struct regmap *map = dev_get_drvdata(dev);
-	unsigned int status;
-	int err;
+	unsigned int status, century, secs;
 	unsigned char buf[8];
+	int err;
 
 	err = regmap_read(map, DS1347_STATUS_REG, &status);
 	if (err)
@@ -60,9 +61,19 @@ static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
 	if (status & DS1347_OSF_BIT)
 		return -EINVAL;
 
-	err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8);
-	if (err)
-		return err;
+	do {
+		err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8);
+		if (err)
+			return err;
+
+		err = regmap_read(map, DS1347_CENTURY_REG, &century);
+		if (err)
+			return err;
+
+		err = regmap_read(map, DS1347_SECONDS_REG, &secs);
+		if (err)
+			return err;
+	} while (buf[0] != secs);
 
 	dt->tm_sec = bcd2bin(buf[0]);
 	dt->tm_min = bcd2bin(buf[1] & 0x7f);
@@ -70,7 +81,7 @@ static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
 	dt->tm_mday = bcd2bin(buf[3]);
 	dt->tm_mon = bcd2bin(buf[4]) - 1;
 	dt->tm_wday = bcd2bin(buf[5]) - 1;
-	dt->tm_year = bcd2bin(buf[6]) + 100;
+	dt->tm_year = (bcd2bin(century) * 100) + bcd2bin(buf[6]) - 1900;
 
 	return 0;
 }
@@ -78,6 +89,7 @@ static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
 static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
 {
 	struct regmap *map = dev_get_drvdata(dev);
+	unsigned int century;
 	unsigned char buf[8];
 	int err;
 
@@ -92,19 +104,18 @@ static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
 	buf[3] = bin2bcd(dt->tm_mday);
 	buf[4] = bin2bcd(dt->tm_mon + 1);
 	buf[5] = bin2bcd(dt->tm_wday + 1);
-
-	/* year in linux is from 1900 i.e in range of 100
-	in rtc it is from 00 to 99 */
-	dt->tm_year = dt->tm_year % 100;
-
-	buf[6] = bin2bcd(dt->tm_year);
+	buf[6] = bin2bcd(dt->tm_year % 100);
 	buf[7] = bin2bcd(0x00);
 
-	/* write the rtc settings */
 	err = regmap_bulk_write(map, DS1347_CLOCK_BURST, buf, 8);
 	if (err)
 		return err;
 
+	century = (dt->tm_year / 100) + 19;
+	err = regmap_write(map, DS1347_CENTURY_REG, century);
+	if (err)
+		return err;
+
 	return regmap_update_bits(map, DS1347_STATUS_REG,
 				  DS1347_NEOSC_BIT | DS1347_OSF_BIT, 0);
 }
-- 
2.21.0