To resume normal operation after a total power loss (no or empty
battery) the "Power-On Reset Override (PORO)" facility needs to be
disabled.
As the oscillator may take a long time (200 ms to 2 s) to resume normal
operation. The default behaviour is to use the PORO facility. But with
the PORO active no interrupts are generated on the interrupt pin (INT).
Signed-off-by: Philipp Rosenberger <p.rosenberger@xxxxxxxxxx>
---
drivers/rtc/rtc-pcf2127.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c
index 39a7b5116aa4..378b1ce812d6 100644
--- a/drivers/rtc/rtc-pcf2127.c
+++ b/drivers/rtc/rtc-pcf2127.c
@@ -26,6 +26,7 @@
/* Control register 1 */
#define PCF2127_REG_CTRL1 0x00
+#define PCF2127_BIT_CTRL1_POR_OVRD BIT(3)
#define PCF2127_BIT_CTRL1_TSF1 BIT(4)
/* Control register 2 */
#define PCF2127_REG_CTRL2 0x01
@@ -612,6 +613,23 @@ static int pcf2127_probe(struct device *dev, struct regmap *regmap,
ret = devm_rtc_nvmem_register(pcf2127->rtc, &nvmem_cfg);
}
+ /*
+ * The "Power-On Reset Override" facility prevents the RTC to do a reset
+ * after power on. For normal operation the PORO must be disabled.
+ */
+ regmap_clear_bits(pcf2127->regmap, PCF2127_REG_CTRL1,
+ PCF2127_BIT_CTRL1_POR_OVRD);
+ /*
+ * If the PORO can't be disabled, just move on. The RTC should
+ * work fine, but functions like watchdog and alarm interrupts might
+ * not work. There will be no interrupt generated on the interrupt pin.
+ */
+ ret = regmap_test_bits(pcf2127->regmap, PCF2127_REG_CTRL1, PCF2127_BIT_CTRL1_POR_OVRD);
+ if (ret <= 0) {
+ dev_err(dev, "%s: can't disable PORO (ctrl1).\n", __func__);
+ dev_warn(dev, "Watchdog and alarm functions might not work properly\n");
+ }
+
/*
* Watchdog timer enabled and reset pin /RST activated when timed out.
* Select 1Hz clock source for watchdog timer.
--
2.29.2
