[i2c] I2C Linux driver terminology and ARM926EJ (AMBA) I2C driver

[Drasko Draskovic]

Hi all.
After reading the docs, I am still a bit confused about terminology used by
lm-sensors team. I have to implement i2c driver for my specific hardware,
that is based on ARM926EJ and AMBA bus. As I can see, there is not support
for I2C interface that sits on AMBA bus (APB part of AMBA) and is on the
other side connected to peripherals via I2C bus. So, that interface, called
ApI2c, is bridge between I2C and AMBA bus. I have to write driver to
describe it, and I am confused what files to look.

I have several questions that are unclear to me, so maybe someone can answer
these. As I understand now correctly, first of all I have to describe
interface, called ApI2c that sits on AMBA bus on one side and is connected
to I2C bus on the other side, so devices (peripherals) connected to I2C bus
talk to microcontroller via this bridge.

1) Is this (ApI2c bridge) "Adapter" in I2C teminology?

2) Do all the files in "buses" directory decsribe such a "bridges" that are
harware specific (tha is, do "busses" directory hold description for
different "adapters", if these are adapters...)? If so, I have to write part
of the driver that describes my bridge, that is ApI2c for AMBA, and put it
in "busses" folder. Following your instructions, I have to inform amba
driver that this "bridge" is another amba_device, and register it within
else amba devices. Is this correct?

3) Suppose I do not want to connect any I2C peripheral for now. So, I do not
need "chips" part of the driver. I just want to enable the functionality for
these chips (with their appropriate drivers) to be inserted later. Question
is, how will I know (test) thah I enabled this functionality correctly? That
means, when I change arch/arm/<mach-yourboard>/core.c file, and write ApI2c
bridge decription (which I put in "busses" folder), and succesfuly compile
kernel (or maybe this has to be loaded as a module?), under which directory
in Linux will I see this "bridge" driver? How can I test it -- send some
messages to it? Are there some userspace tools that can do that? I am asking
this question because this "bridge" (ApI2c) is not a device in a strict
sense. Devices are peripherals connected to I2C bus, and described with
their own drivers from "chips" directory. So how is this "bridge" driver
treated by Linux, and where I can see that it exists and that is wrote
correctly, and how can I test it/talk to microcontrollet thru it?

4) What is exactly in "algo" folder. What are these algorithms? Does not one
describe the functionality of such a bridge within "busses" folder? Do I
need some file in "algo" folder (preferably not). If not, do I have to
implemant some algorithm within my "bridge" file, which will sit in "busses"
directory? What are these algorithms exactly, when we have
protocol described in i2c-core file?

Best regards,
-- 
Drasko DRASKOVIC

Software Developer
Elsys-DESIGN
Belgrade, Serbia
Tel. +381.11.311.5252
Fax. +381.11.311.5251
www.elsys-design.com
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