rtc: ds1347: handle century register

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

Link: https://lore.kernel.org/r/20191007134724.15505-10-alexandre.belloni@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/drivers/rtc/rtc-ds1347.c b/drivers/rtc/rtc-ds1347.c
index a49ce99919160340fe6bbcf7590dfd875b47aa03..7025cf3fb9f8df8e31ecece54df76cd80a8f8a7f 100644 (file)
--- 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);
 }