[U-Boot] [Turris Omnia] Is there a standard approach to write a driver for CryptoAuthentication/EEPROM chip?

[Marek Behún]

Hello,
I have few questions about upstreaming support for the Turris Omnia
into u-boot.

The Turris Omnia has (on I2C interface) an Atmel ATSHA204
CryptoAuthentication chip for storage of MAC adresses, device serial
number, device configuration (1 GB RAM vs 2 GB RAM). This data is
stored in the internal EEPROM of ATSHA204. The chip is capable of more:
for example there is also a random number generator. For more info see
http://www.atmel.com/Images/Atmel-8740-CryptoAuth-ATSHA204-Datasheet.pdf

I want to write support for the ATSHA204 for upstream U-Boot so that I
can then continue working on support for Turris Omnia. Currently we
have our internal branch of U-Boot, in which the ATSHA204 code is in
drivers/misc (see
https://gitlab.labs.nic.cz/turris/turris-omnia-uboot/blob/master/drivers/misc/atsha204-i2c.c
).

My question: Does U-Boot have a standard approach how to write a driver
for such a chip? Does this device need to be defined in the Device Tree?

Thank you.

Marek