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 <[email protected]> --- 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
