Reading wm8994 regs over i2c

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On a discovery board with a wm8994 should I be able to both read and write all control registers over i2c?

I am trying to verify settings by reading them back after writing. I get reliable reads from some of the lower registers (under 0x0100), but above that I generally get 0.

I can't see anything in the data sheet saying I can't read from them, but wanted to double check before I start a possibly fruitless investigation.

Thanks,

Stephen