communication with i2c client

[Ladislav Klenovič]

Hi,
I've create an i2c client and my questions is how to access it from userspace. This client is sitttng on adapter that  I was able to access via /dev interface. After the client were successfuly loaded and detected,
ioctl(fd,I2C_SLAVE,...) and read/write functions didn't work and  error messages like "device busy" or "ioctl error" have occured. Also my debug messages from i2c client didn't arise when I am accessing 
device only adapter's.
How to (standardly) access a an i2c client? 
Do I need to create an ioctl interface or exports some helper function for access it from user space and also from kernel space?  

regards,
Ladislav.