Linux Device Drivers Development

The bus

A bus is a channel link between devices and processors. The hardware entity that manages the bus and exports its protocol to devices is called the bus controller. For example, the USB controller provides USB support. The I2C controller provides I2C bus support. Therefore, the bus controller, being a device on its own, must be registered like any device. It will be the parent of devices that need to sit on the bus. In other words, every device sitting on the bus must have its parent field pointing to the bus device. A bus is represented in the kernel by the struct bus_type structure:

struct bus_type { const char *name; const char *dev_name; struct device *dev_root; struct device_attribute *dev_attrs; /* use dev_groups instead */ const ...