rtc: pcf85063: Always clear EXT_TEST from set_time

Power-on reset after the insertion of a battery does not always complete
successfully, leading to corrupted register content. The EXT_TEST bit
will stop the clock from running, but currently the driver will never
recover.

Safely handle the erroneous state by clearing EXT_TEST as part of the
usual set_time method.

Signed-off-by: Phil Elwell <phil@raspberrypi.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20211015111208.1757110-1-phil@raspberrypi.com

diff --git a/drivers/rtc/rtc-pcf85063.c b/drivers/rtc/rtc-pcf85063.c
index 3e59590..4a70d6b 100644 (file)
--- a/drivers/rtc/rtc-pcf85063.c
+++ b/drivers/rtc/rtc-pcf85063.c
@@ -34,6 +34,7 @@
 #define PCF85063_REG_CTRL1             0x00 /* status */
 #define PCF85063_REG_CTRL1_CAP_SEL     BIT(0)
 #define PCF85063_REG_CTRL1_STOP                BIT(5)
+#define PCF85063_REG_CTRL1_EXT_TEST    BIT(7)
 
 #define PCF85063_REG_CTRL2             0x01
 #define PCF85063_CTRL2_AF              BIT(6)
@@ -117,6 +118,7 @@ static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm)
         * reset state until all time/date registers are written
         */
        rc = regmap_update_bits(pcf85063->regmap, PCF85063_REG_CTRL1,
+                               PCF85063_REG_CTRL1_EXT_TEST |
                                PCF85063_REG_CTRL1_STOP,
                                PCF85063_REG_CTRL1_STOP);
        if (rc)