[i2c] Userspace Headers for recent kernels

[don]

On Tue, Sep 19, 2006 at 10:14:06PM +0200, Jean Delvare wrote:
> Hi Don,
> 
> > I am trying to find or create some header files (i2c-dev.h and i2c.h
> > if needed).  That will work for user-space programs with recent kernels
> > like 2.6.17.13.
> > 
> > I have read the various messages in this lists archives and elsewhere
> > which say:
> > 
> > 	- The kernel headers are not for users (no kidding they produce
> > 	  copious errors).
> > 
> > 	- The Lm-sensors headers should be used.
> > 
> > However all the versions of lm-sensors I have found, including the current
> > SVN, don't seem to match the kernel code.  For example the function
> > i2c_smbus_write_byte() in the kernel wants a struct i2c_client while the
> > lm-sensors file declares it with an int (a file number).
> > 
> > Am I missing something?  If not does anyone have such headers?
> 
> The file you need is indeed kernel/include/i2c-dev.h from the
> lm_sensors package. It is installed
> as /usr/local/include/linux/i2c-dev.h by "make user_install. This file
> will work for both 2.4 and 2.6 kernels.
> 
> Some of the inline functions declared in this file have the same name
> as some functions in the kernel, because they are similar in spirit.
> However, the kernel structure are not available from user-space.
> User-space uses ioctls to control the kernel (bus) drivers, and the
> inline functions in i2c-dev.h are wrappers for these ioctls. If you are
> confused by the different function signatures, just consider that the
> similar names are unfortunate. These are really different functions.
> 
> For a simple example of user-space tool using i2c-dev, please see
> prog/dump/i2cset.c in the lm_sensors package.

Thanks for the reply.  Yes I already have been looking at that code.
It doesn't work for me and I am trying to figure out why.

Can you point me at the code that implements the version of
i2c_smbus_write_byte() that is used by this program?  The only one I can
find is in the kernel?  I probably need to include some function or library
with my small app.

Thanks
Don