I2c-dev.c is part of I2C equipment, access interface device, the access to the hardware is realized by i2c_adapter. It is during initialization, need to register a i2c_driver to the I2C Core. I think this is just to let the user access layer of I2C b

* This supports access to SPI devices using normal userspace I/O calls. * Note that while traditional UNIX/POSIX I/O semantics are half duplex, * and often mask message boundaries, full SPI support requires full duplex * transfers. There ar