I2C: kernel & userspace drivers : using i2c-stub

[anish singh]

does I2c-stub create the /dev node?If it is not creating then you
have to do it yourself.


On Mon, Apr 22, 2013 at 5:11 PM, Sagar Padhye <sgr.m.pdy at gmail.com> wrote:

> Hi,
>
> [USING : Ubuntu 12.04 LTS]
>
> I am trying to learn I2C subsystem. I havent found much of well documented
> things that can help a newbie on google. I just chose to read the linux
> kernel documentation txts.
>
> I read the way kernel can interact with i2c through both SMBus calls & raw
> file op calls (ioctl, read, write). It looks good till that point.
>
> The doc also tells about i2c stub. which can be used as follows:
>  1. load the i2c module
> 2. use i2cset (from the i2c-tools project) to pre-load some data
> 3. load the target chip driver module
>  4. observe its behavior in the kernel log
>
> I was able to achieve just the 1st step here. I loaded the module
> successfully.
> $ sudo modprobe i2c-stub chip_addr=0x023
>
> I got following Kern msg
> $dmesg
> ...
> [658.071706]   i2c-stub: Virtual chip at 0x23
>
> So I believe that step 1 is clear.
>
> in second step I have no idea how to provide needed inputs to command
> ->
> Usage : i2cset [-f] [-y] [-m mask] I2CBUS CHIP-ADDRESS DATA-ADDRESS
> [VALUE] [MODE]
> I tried to give I2CBUS = 0, Chip addr = 0x23 & data addr=0 but it gives
> error
> Error : Could not open file '/dev/i2c-0' or '/dev/i2c/0' : No such file or
> directory
>
> There is no file at all created in /dev corrosponding to this device.
>
> Any idea how to use i2c properly? Is this an ubuntu only problem? Can
> anybody provide a good tutorial like thing to learn about i2c kernel &
> userspace driver programming?
>
> --
> Thanks and Regards,
> Sagar
>
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