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It turns out that as documented, PCF8563_R_SECOND_VL (i.e. battery low)

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doesn't automatically clear when VDD rises above Vlow again and needs to be
cleared manually. However, apparently this needs all of the time registers
to be set, i.e. pcf8563_settime(), and not just PCF8563_R_SECOND in order
for PCF8563_R_SECOND_VL to stick. Thus, we just issue a warning during
pcf8563_attach() rather than failing with ENXIO in case it is set.

MFC after:	3 days
This commit is contained in:
Marius Strobl 2012-10-18 10:29:16 +00:00
parent 470797ab8e
commit f9e26776a6
1 changed files with 11 additions and 3 deletions
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14
sys/dev/iicbus/pcf8563.c
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@ -83,6 +83,16 @@ pcf8563_attach(device_t dev)
if (sc->sc_addr == 0)
sc->sc_addr = PCF8563_ADDR;
/*
* NB: PCF8563_R_SECOND_VL doesn't automatically clear when VDD
* rises above Vlow again and needs to be cleared manually.
* However, apparently this needs all of the time registers to be
* set, i.e. pcf8563_settime(), and not just PCF8563_R_SECOND in
* order for PCF8563_R_SECOND_VL to stick. Thus, we just issue a
* warning here rather than failing with ENXIO in case it is set.
* Note that pcf8563_settime() will also clear PCF8563_R_SECOND_VL
* as a side-effect.
*/
msgs[0].slave = msgs[1].slave = sc->sc_addr;
error = iicbus_transfer(device_get_parent(dev), msgs, sizeof(msgs) /
sizeof(*msgs));
@ -90,10 +100,8 @@ pcf8563_attach(device_t dev)
device_printf(dev, "%s: cannot read RTC\n", __func__);
return (error);
}
if ((val & PCF8563_R_SECOND_VL) != 0) {
if ((val & PCF8563_R_SECOND_VL) != 0)
device_printf(dev, "%s: battery low\n", __func__);
return (ENXIO);
}
sc->sc_year0 = 1900;
clock_register(dev, 1000000); /* 1 second resolution */