PCA954x I2C switch/multiplexer

PCA954x I2C switch/multiplexer

[ROASCIO Paolo]

Hello, i'm new in this list, then please excuse me for my bad english...

I read the Frank's message dated jan 31 2008 about a patch for the PCA954x i2c 
mux family support.

I patched my kernel (2.6.22) without problems, bu when i load the module 
i2c_pca954x, nothing happens....

If i turn on all the kernel i2c debug related options, in dmesg i can see 
something like:

[pca9540] registered,

but, when i launch sensors-detect, i can't see any bus other than my 
i2c-amd-756.

I'm not a programmer, but reading the code, i can see that this module hasn't 
load parameters (the same result as modinfo), then, please Frank, can you 
explain me how to make the pca954x support start?

I'm a GIGABYTE GA-7DPXDW owner, where a PCA9540 "shares" two LM-90 on the sam 
i2c bus (one for each cpu), then i will be happy to test your patch if right 
pointed.

Thanks.

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Re: PCA954x I2C switch/multiplexer

[Edelhaeuser, Frank]

The driver I submitted implements the "new style" driver model. These
driver's don't probe the bus automatically. Instead, devices must be
instantiated by calling i2c_register_board_info() for each multiplexer
device. Please note that this driver implements a special syntax for the
type field: e.g. .type = "pxa9544,5" tells the driver to create 4
virtual i2c buses with ids 5, 6, 7 and 8. You would
i2c_register_board_info() your PXA9544 multiplexer with the root i2c bus
and your bus segment devices with those virtual i2c buses.

Regards,
-Frank

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Re: PCA954x I2C switch/multiplexer

[Jean Delvare]

Hi Frank,

On Sun, 24 Feb 2008 21:41:54 -0800, Edelhaeuser, Frank wrote:
> The driver I submitted implements the "new style" driver model. These
> driver's don't probe the bus automatically. Instead, devices must be
> instantiated by calling i2c_register_board_info() for each multiplexer
> device. Please note that this driver implements a special syntax for the
> type field: e.g. .type = "pxa9544,5" tells the driver to create 4
> virtual i2c buses with ids 5, 6, 7 and 8. You would
> i2c_register_board_info() your PXA9544 multiplexer with the root i2c bus
> and your bus segment devices with those virtual i2c buses.

Please don't abuse the type field, instead define a custom structure
and pass it to the driver as platform data. This will give you much
more flexibility as well.

-- 
Jean Delvare

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Re: PCA954x I2C switch/multiplexer

[ROASCIO Paolo]

Il Monday 25 February 2008 09:02:37 hai scritto:
> Hi Frank,
>
> On Sun, 24 Feb 2008 21:41:54 -0800, Edelhaeuser, Frank wrote:
> > The driver I submitted implements the "new style" driver model. These
> > driver's don't probe the bus automatically. Instead, devices must be
> > instantiated by calling i2c_register_board_info() for each multiplexer
> > device. Please note that this driver implements a special syntax for the
> > type field: e.g. .type = "pxa9544,5" tells the driver to create 4
> > virtual i2c buses with ids 5, 6, 7 and 8. You would
> > i2c_register_board_info() your PXA9544 multiplexer with the root i2c bus
> > and your bus segment devices with those virtual i2c buses.
>
> Please don't abuse the type field, instead define a custom structure
> and pass it to the driver as platform data. This will give you much
> more flexibility as well.

Hello, thanks for your answers

Well, i googled this days to learn something about the 
i2c_register_board_info() and the platform data structures. This requires a 
good knowledge of programming as i haven't :(

I understood that pca9540 (in my case) definitions have to be hardcoded 
somewhere (the only thread i found about this regards a SIP device 
registration on arm platform), but, where? and these needs to be coded as 
a "C" struct (the "type" field is part of this struct?)?

Well, i think i'm not enough skinned to manage this driver, peraph a whish: 
will be implemented something like a modprobe option to make this driver more 
user friendly?

Please feel free to point me to adequate documentation about the platform data 
structure, in the meanwhile i continue googling...

 
Roascio paolo

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