Re: [PATCH RFC] eeprom: at24: extend driver to plug into the NVMEM framework

[Andrew Lunn <andrew@lunn.ch>]

> It's true that this is something that we might have overlooked. Is it
> expected to maintain that compatibility when moving a driver from one
> framework to another (and this is a real question, not a troll)?

Yes. There will be user space applications reading from the eeprom
file in /sys. In fact, until the NVMEM framework arrived, it was not
easy to access the eeprom from kernel space, meaning the majority of
users must of been user space...
 
> If so, we might provide a compatibility layer to add the former file
> too, protected by a kconfig option maybe ?

There is one other detail you might of missed. Both AT24 and AT25 do
have an in kernel API. In the at24_platform_data you can have a
callback function "setup" which gets called when the device is
probed. setup() is called with a struct memory_accessor which contains
function pointers for reading and writing to the EEPROM. A few
platforms use these for getting the MAC address out of the EEPROM.
And these platforms are old style, not DT.

    Andrew