rtc: ds1307: Ensure oscillator is enabled for DS1388

Similar to the other variants the DS1388 has a bit to stop the
oscillator to reduce the power consumption from VBAT. Ensure that the
oscillator is enabled when the system is up.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20200816235731.21071-1-chris.packham@alliedtelesis.co.nz

diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index 54c85cdd019dda2b3dcf43f6144d10259598c80d..2182f4e97c0a3977d7a1702e1e43ed4bde7a1c19 100644 (file)
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -153,6 +153,7 @@ enum ds_type {
 #define DS1388_REG_CONTROL             0x0c
 #      define DS1388_BIT_RST           BIT(0)
 #      define DS1388_BIT_WDE           BIT(1)
+#      define DS1388_BIT_nEOSC         BIT(7)
 
 /* negative offset step is -2.034ppm */
 #define M41TXX_NEG_OFFSET_STEP_PPB     2034
@@ -1881,6 +1882,19 @@ static int ds1307_probe(struct i2c_client *client,
                                     DS1307_REG_HOUR << 4 | 0x08, hour);
                }
                break;
+       case ds_1388:
+               err = regmap_read(ds1307->regmap, DS1388_REG_CONTROL, &tmp);
+               if (err) {
+                       dev_dbg(ds1307->dev, "read error %d\n", err);
+                       goto exit;
+               }
+
+               /* oscillator off?  turn it on, so clock can tick. */
+               if (tmp & DS1388_BIT_nEOSC) {
+                       tmp &= ~DS1388_BIT_nEOSC;
+                       regmap_write(ds1307->regmap, DS1388_REG_CONTROL, tmp);
+               }
+               break;
        default:
                break;
        }