Problem with PCF8563 RTC on Raspberry

[Bernd Walter]

I'm trying to get the RTC on a Waveshare ARPI600 module running on a
Raspberry Pi B.
This is the Overlay I'm using:
/dts-v1/;
/plugin/;

&i2c0 {
	 status = "okay";
	  
	  rtc: rtc at 51 {
		  compatible = "nxp,pcf8563";
		  reg = <0x51>;
	  };
};

IICbus gets probed during boot:
iicbus0: <OFW I2C bus> on iichb0
iic0: <I2C generic I/O> on iicbus0
iicbus0: <unknown card> at addr 0xa2

When I load the nxprtc moduele I get the following error:
nxprtc0: <NXP PCF8563 RTC> at addr 0xa2 on iicbus0
nxprtc0: cannot set up timer

I wonder if I miss something, e.g. setting GPIO.
However, for spi0 no GPIO setup was required and the overlay looks
quite similar.

-- 
B.Walter <bernd at bwct.de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.