How should I use kernel-defined i2c structs in this driver

From: Andrey Utkin
Date: Thu May 26 2016 - 10:08:14 EST

Could anybody please give a hint - which kernel-defined i2c objects, and how
many of them, I need to define and use to substitute these driver-defined
functions i2c_read(), i2c_write() ?
In a word, there's 4 chips with different addresses, to which this code
communicates via main chip's dedicated registers.
Do i need a single i2c_adapter or several?
Do i need i2c_client entities?
where should I put what is named "devid" here?

Thanks in advance.