> > I'm assuming that a kernel space chip driver like our gpio expander > (pca953x.c) also uses the same adapter driver as my user-space > application since that expander chip is on the same bus. > > Let's clarify right away: i2c-dev (which handles /dev/i2c-* nodes) is > NOT an adapter driver. It is a bridge driver between user-space and > your adapter driver. Your adapter driver is most likely one living in > drivers/i2c/busses, and depends on the actual hardware you run on. OK, thanks that's clear. I was confused by the terminology in the dev-interface document. When it said to open an adapter, I thought that meant I was using the associated adapter driver. > > Incorrect. The address isn't written to the adapter, it is a setting > local to i2c-dev and even specific to the file handle you got when > opening a /dev/i2c-* node. Each subsequent read, write or smbus call in > your user-space driver automatically includes the slave address, which > is only valid for the read, write or smbus call in question. Excellent! - in the words of a famous Swiss restaurant's wine menu, this leaves me nothing to hope for! Jean, thank you for your help, it saved me a ton pouring over source code and allowed me to get on with the job at hand. Much appreciated. Regards, Rory -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
