I2C: kernel & userspace drivers : using i2c-stub

[Rami Rosen]

Hi,
I suggest the following:
1) remove /dev/i2c-0 you created (it is ok, but there should be 4
/dev/i2c-? devices)

2) run
modprobe  i2c-dev


i2c-dev is the device driver for i2c. See:
https://www.kernel.org/doc/Documentation/i2c/dev-interface

3) try ls  -a /dev/i2c-*
you should have 4 device files.

4) try to use  i2cset of the i2c-tools project.

5) tell us the results.



best regards,
Rami Rosen
http://ramirose.wix.com/ramirosen


On Tue, Apr 23, 2013 at 8:30 AM, Sagar Padhye <sgr.m.pdy at gmail.com> wrote:
> I tried to use 'mknod /dev/i2c-0 c 89 0' and then tried to use the device.
> but still when I try to use device it gives IO error (so I concluded, I
> created incorrect device)
>
>
> On Mon, Apr 22, 2013 at 7:41 PM, anish singh <anish198519851985 at gmail.com>
> wrote:
>>
>> 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
>>>
>>> _______________________________________________
>>> Kernelnewbies mailing list
>>> Kernelnewbies at kernelnewbies.org
>>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>>>
>>
>>
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>
>
>
> --
> Thanks and Regards,
> Sagar
>
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