I2C: kernel & userspace drivers : using i2c-stub

[Sagar Padhye]

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
>>
>>
>
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>
>


-- 
Thanks and Regards,
Sagar
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20130423/f8eec62a/attachment.html