Add CFG_RTC_DS1337_NOOSC to turn off OSC output

The default settings for RTC DS1337 keeps the OSC
output, 32,768 Hz, on. This add CFG_RTC_DS1337_NOOSC to
turn it off.

Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>

diff --git a/README b/README
index a9663a3..b3423e3 100644 (file)
--- a/README
+++ b/README
@@ -689,6 +689,7 @@ The following options need to be configured:
                CONFIG_RTC_DS164x       - use Dallas DS164x RTC
                CONFIG_RTC_ISL1208      - use Intersil ISL1208 RTC
                CONFIG_RTC_MAX6900      - use Maxim, Inc. MAX6900 RTC
+               CFG_RTC_DS1337_NOOSC    - Turn off the OSC output for DS1337
 
                Note that if the RTC uses I2C, then the I2C interface
                must also be configured. See I2C Support, below.

diff --git a/drivers/rtc/ds1337.c b/drivers/rtc/ds1337.c
index 50ab446..69ab2bf 100644 (file)
--- a/drivers/rtc/ds1337.c
+++ b/drivers/rtc/ds1337.c
@@ -158,11 +158,18 @@ void rtc_set (struct rtc_time *tmp)
  * SQW/INTB* pin and program it for 32,768 Hz output. Note that
  * according to the datasheet, turning on the square wave output
  * increases the current drain on the backup battery from about
- * 600 nA to 2uA.
+ * 600 nA to 2uA. Define CFG_RTC_DS1337_NOOSC if you wish to turn
+ * off the OSC output.
  */
+#ifdef CFG_RTC_DS1337_NOOSC
+ #define RTC_DS1337_RESET_VAL \
+          (RTC_CTL_BIT_INTCN | RTC_CTL_BIT_RS1 | RTC_CTL_BIT_RS2)
+#else
+ #define RTC_DS1337_RESET_VAL (RTC_CTL_BIT_RS1 | RTC_CTL_BIT_RS2)
+#endif
 void rtc_reset (void)
 {
-       rtc_write (RTC_CTL_REG_ADDR, RTC_CTL_BIT_RS1 | RTC_CTL_BIT_RS2);
+       rtc_write (RTC_CTL_REG_ADDR, RTC_DS1337_RESET_VAL);
 }