Finding particular I2C adapter?

Finding particular I2C adapter?

[Przemyslaw Wegrzyn]

Hi!

First of all - I know what I'm asking for is somewhat "broken by
design", but anyway...

I'm about to develop a driver for a custom chip attached to SMBus in a
sort of industrial PC (choosing SMBus was a really bad idea, imho, but
unfortunately I can't change hardware team decisions).

While developing the I2C client driver seems pretty straight-forward,
I'm slightly confused about making it look for the device on a
particular I2C adapter instance. The project is limited to particular
board types, each using ICH chipset, so I need to use i2c_adapter
controlled by i2c-i801 module.

Here's my understanding so far:

- it is not an embedded system in a strict sense -> thus no
i2c_board_info -> no static I2C configuration

- AFAIR I can force the bus and address using 'force' parameter at
module loading time (e.g. via /etc/modules), but the I2C adapter number
is not static anyway on PC, and depend on e.g. adapter modules loading
order, so I'm a bit afraid of users breaking this configuration too easily.

- similar issue with echo'ing to /sys/bus/i2c/devices/i2c-<n>/new_device
- I need to know the bus ID in advance

Ideally, I'd like to have a sort of wrapper module that will find the
proper i2c_adapter and instantiate my i2c_client explicitly. Yet I know
that iterating i2c adapters is discouraged at least (actually, is there
any API now allowing for this? calling i2c_get_adapter with successive
numbers is clearly a hack).

Any ideas?

BR,
Przemek

Re: Finding particular I2C adapter?

[Przemyslaw Wegrzyn]

On 10/07/2011 02:43 PM, Przemyslaw Wegrzyn wrote:
> Ideally, I'd like to have a sort of wrapper module that will find the
> proper i2c_adapter and instantiate my i2c_client explicitly. Yet I know
> that iterating i2c adapters is discouraged at least (actually, is there
> any API now allowing for this? calling i2c_get_adapter with successive
> numbers is clearly a hack).
Answering my own question - there's i2c_for_each_dev() that I've
overlooked before. Still a hack, anyway.

--
Przemek