Hi everyone,

> Perhaps we should first think through what an ancillary device really
> is.  My understanding is that it is used to talk to secondary addresses
> of a multi-address I2C slave device.

As I mentioned somewhere before, this is not the case. Ancillary devices
are when one *driver* handles more than one address. Everything else has
been handled differently in the past (for  all the uses I am aware of).

Yet, I have another idea which is so simple that I wonder if it maybe
has already been discussed so far?

* have two regs in the bindings
* use the second reg with i2c_new_client_device to instantiate the
  RTC sibling. 'struct i2c_board_info', which is one parameter, should
  have enough options to pass data, e.g it has a software_node.

Should work or did I miss something here?

Happy hacking,

   Wolfram