Re: I2C: kernel & userspace drivers : using i2c-stub

[Sagar Padhye <sgr.m.pdy@xxxxxxxxx>]

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@xxxxxxxxx> 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@xxxxxxxxx> 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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--

Thanks and Regards,

Sagar

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