[i2c] [lm-sensors] I2C for uCLinux on ARM926EJ (with AMBA bus)

[Mark M. Hoffman]

Hi:

(Again... moving to i2c list)

* Drasko Draskovic <drasko.draskovic at gmail.com> [2006-08-01 17:35:11 +0200]:
> On 8/1/06, Drasko Draskovic <drasko.draskovic at gmail.com> wrote:
> >
> >
> >Hi. I am working on a custom design that is based on ARM926EJ and AMBA
> >bus. OS of choice is uCLinux, patched with RTAI for RT performance. I
> >have to implement now I2C support, but looking at the existing driver
> >things seem a bit unclear for me.
> >
> >Here is what I unserstood:
> >i2c-core.c is independent of the bus and is kernel module. This should
> >be working. But  what about AMBA bus? Is it supported? Is this file for
> >support of AMBA located in 'busses' directory? What are algos files? As
> >I undersand, these are bus dependent. Is AMBA supported by these?
> >
> >If there are not, does anyone have idea how these can be written?
> >
> >How can a proper working of I2C be tested? Can some dummy I2C
> >peripheral be created in Linux?
> >
> >Any information will be more than helpful.
> >
> >
> I also want to ask following things:
> ARM has Amba Peripheral I2C Bus Controller (ApI2c), which I guess is a
> bridge between Amba and I2C (which comes out of the chip on two pins).

Ah, OK.  That's the thing for which you want to write an "adapter" driver.

> So, can you tell me:
> 1) what abot 'buses' part? It has to be dependeant on Amba?

You will need a driver in drivers/i2c/busses that supports the API2C.

> 2) what about 'chips part? Does it have to depend on ApI2c?

You may (or may not) need a driver in driver/i2c/chips to support whatever
it is that you plan to connect to your I2C bus.  Drivers in this directory
are independent of the I2C bus/adapter drivers.

Or, you could drive your I2C slave devices completely from userspace using
the i2c-dev mechanism.

> 3) Do I have to write only adapter part -- is this the peice of code
> that is ApI2c dependant, and not 'chips' part?

I don't know what you "have" to do.  In your first message you mention
"implement now I2C support".  This probably means (at least) writing an
API2C bus/adapter driver.

> I am still not clear which part of driver ('algos', 'busses', and
> 'chips') depends on what... And waht of existing I can use from existing and
> what I
> have to write by myself.

Read Documentation/i2c/* please.

Regards,

-- 
Mark M. Hoffman
mhoffman at lightlink.com