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Ensuring clock input to RTC_XTALI on iMX6 is detected as "used" by CCF

Question asked by Glyn Cowe on May 29, 2019
Latest reply on May 29, 2019 by igorpadykov

I am working on a custom board design using a PCF8563 RTC as 32kHz input to RTC_XTALI on iMX6Q running Linux. I have found that the PCF8563 driver stops the output clock on initialisation (for power-saving), then enables it when the prepare function is called (from the Common Clock Framework, CCF). The trouble is that the prepare function is never called, seemingly since the CCF considers the clock as "unused". The driver is correctly loaded and I can read and write the time, but the clock output is left disabled.

When I hack out the code in the driver that disables the output clock, the PCF8563 outputs clocks as it should. This is an ugly hack, though, and I suppose that I need to do something in the device tree to ensure that the CCF knows that the PCF8563 is used. Please could anyone point me in the right direction?