Linux MPC8xx I2C Interface

Jeff Stevens jsteve17 at
Wed Feb 4 01:46:48 EST 2004

I am working on a proprietary board which I have
U-Boot and ELDK Linux ported over to.  On the board
there is an I2C bus that first connects to a PCA9556
(I2C Hub Controller at 0x18) & PCA9516 (I2C Octal
Hub).  So I need to be able to talk to the PCA9556 to
set up the hub controller to activate one of the bus
segments on the hub.  I am able to read and write to
all my I2C devices under U-Boot, but not under Linux.
I have tried both compiling, and creating modules of
i2c-core, i2c-dev, and i2c-algo-8xx.  I also patched
the kernel with the i2c patch which also gave me
i2c-proc.  I don't get any errors when I boot with
them compiled into the kernel, or when I insert them
as modules.  However, I don't see any devices.  What
am I doing wrong?  Also, I would rather talk to the
I2C devices directly through the CPM interface, and
not through the dev interface.  Is there a way to do
this?  Is there any good documentation out there?

Thanks in advace,
   Jeff Stevens

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