If the PCF2127/2129 loses power it needs some initialization to work
correctly. A bootloader/firmware might do this. If not we should do this
in the driver.
Changes for v2:
- make commit log and comments more clear
- check if PORO was really disabled
Philipp Rosenberger (2):
rtc: pcf2127: Disable Power-On Reset Override
rtc: pcf2127: Run a OTP refresh if not done before
drivers/rtc/rtc-pcf2127.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
Interdiff against v1:
diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c
index f012b989f2f2..ca56dba64e79 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
@@ -616,18 +617,27 @@ static int pcf2127_probe(struct device *dev, struct
regmap *regmap,
}
/*
- * Disable the Power-On Reset Override facility to start normal
- * operation. If the operation should fail, just move on. The RTC should
- * work fine, but functions like watchdog and alarm interrupts might
- * not work.
+ * The "Power-On Reset Override" facility prevents the RTC to do a reset
+ * after power on. For normal operation the PORO must be disabled.
*/
- ret = regmap_clear_bits(pcf2127->regmap, PCF2127_REG_CTRL1,
+ regmap_clear_bits(pcf2127->regmap, PCF2127_REG_CTRL1,
PCF2127_BIT_CTRL1_POR_OVRD);
- if (ret) {
+ /*
+ * 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");
}
+ /*
+ * Set the OTP refresh bit unconditionally. If an OTP refresh was
+ * already done the bit is already set and will not rerun the refresh
+ * operation.
+ */
ret = regmap_set_bits(pcf2127->regmap, PCF2127_REG_CLKOUT,
PCF2127_BIT_CLKOUT_OTPR);
if (ret < 0) {
--
2.29.2
