Re: How can I use two command bytes for a block read?

Re: How can I use two command bytes for a block read?

[Guenter Roeck]

On Fri, Aug 12, 2011 at 05:21:15AM -0400, Wayne Tams wrote:
> Hi,
> 
> I am having a little bother interfacing with a device that requires two command
> bytes for both reads and writes. I can perform a successful write using I2C
> writes but I would rather use the user-space i2c_smbus_ functions from
> i2c-dev.h. In the i2c-dev documentation (http://lxr.free-electrons.com/source/
> Documentation/i2c/smbus-protocol?v=2.6.35;a=arm#L225) there is a mention of a
> two byte command block read but there does not appear to be any supporting
> function in i2c-dev.h. Is there a patch available to add this functionality or
> could there be another approach?
> 
> Just to clarify I need my smbus read transaction to look like this:
> 
> 
> 
>  S Addr Wr [A] Comm1 [A] Comm2 [A] S Addr Rd [A] [Data] A [Data] A ... A [Data] NA P
> 
> Thanks
> 
> Wayne

Wrong mailing list. Try linux-i2c@vger.kernel.org (copied).

As a general hint, eeprom drivers such as drivers/misc/eeprom/at24.c do this;
you might want to have a look.

Guenter


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Re: How can I use two command bytes for a block read?

[Wayne Tams]

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Oops apologies, though your advice helped, problem solved.

Thanks

Wayne

On Fri, Aug 12, 2011 at 3:29 PM, Guenter Roeck
<guenter.roeck@ericsson.com>wrote:

> On Fri, Aug 12, 2011 at 05:21:15AM -0400, Wayne Tams wrote:
> > Hi,
> >
> > I am having a little bother interfacing with a device that requires two
> command
> > bytes for both reads and writes. I can perform a successful write using
> I2C
> > writes but I would rather use the user-space i2c_smbus_ functions from
> > i2c-dev.h. In the i2c-dev documentation (
> http://lxr.free-electrons.com/source/
> > Documentation/i2c/smbus-protocol?v=2.6.35;a=arm#L225) there is a mention
> of a
> > two byte command block read but there does not appear to be any
> supporting
> > function in i2c-dev.h. Is there a patch available to add this
> functionality or
> > could there be another approach?
> >
> > Just to clarify I need my smbus read transaction to look like this:
> >
> >
> >
> >  S Addr Wr [A] Comm1 [A] Comm2 [A] S Addr Rd [A] [Data] A [Data] A ... A
> [Data] NA P
> >
> > Thanks
> >
> > Wayne
>
> Wrong mailing list. Try linux-i2c@vger.kernel.org (copied).
>
> As a general hint, eeprom drivers such as drivers/misc/eeprom/at24.c do
> this;
> you might want to have a look.
>
> Guenter
>
>

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