Hi Michael, > Dear Sir, We are not a sir. We are a number of different people, this is a mailing list. > I am new to Linux and Device driver programming. I am trying > to write a device driver software module to access the ICH6 > SMBus controller on the motherboard of our PC running Linux > 2.6.10 kernel. This driver already exists, it's named i2c-i801. From the below, it seems that you found that already, but your sentence is somewhat confusing nevertheless. > I configured my 2.6.10 kernel to have I2C built-in support > and your i801 module loaded. Then I loaded the i2c-dev > interface module and wrote a short application software to > test the functions for SMBus. After my application opened the > /dev/i2c device, I received messages saying "i2c-adaptor: i2c-0 > -- I2C level transfer not support" when my application software > called the read and write function of the i2c-dev module. Further > tracking inside the i2c-dev module shew that the algorithm > parameter adap->algo->master_xfer = NULL. That means the i801 > driver was not properly loaded by the i2c-dev module. No, this means just what the error message said. The ICH6 is an SMBus master, not an I2C master. SMBus is a subset of I2C. I2C masters can emulate SMBus transactions, but not the other way around. > Could you advise how I can make use of the i801 module and your > i2c-dev module to access the ICH6 SMBus controller? Instead of using read() and write() on the device file, you have to use ioctl(). See in i2c-dev.h (from the lm_sensors project) for a list of available commands. You will at least need I2C_SLAVE to set the target chip address, and I2C_SMBUS to run SMBus transactions. There are helper functions in i2c-dev.h to make your life easier with SMBus transactions, so you shouldn't have to use I2C_SMBUS explicitely. There is some documentation available in the i2c package, or online at: http://www2.lm-sensors.nu/~lm78/cvs/i2c/doc/dev-interface You should take a look at prog/dump/i2cset.c in the lm_sensors package, it is a nice example of how userspace programs can access SMBus. There are a few other test programs in this package, but I think this is the most simple one we have. -- Jean Delvare
