driver-api/driver-model/bus.rst

2 Bus Types
9 int bus_register(struct bus_type * bus);
15 Each bus type in the kernel (PCI, USB, etc) should declare one static
32 When a bus driver is initialized, it calls bus_register. This
33 initializes the rest of the fields in the bus object and inserts it
34 into a global list of bus types. Once the bus object is registered,
35 the fields in it are usable by the bus driver.
45 them are inherently bus-specific. Drivers typically declare an array
46 of device IDs of devices they support that reside in a bus-specific
49 The purpose of the match callback is to give the bus an opportunity to
52 particular device, without sacrificing bus-specific functionality or
53 type-safety.
55 When a driver is registered with the bus, the bus's list of devices is
66 struct device_drivers, respectively. Bus drivers are free to use the
67 lists as they please, but conversion to the bus-specific type may be
72   int bus_for_each_dev(struct bus_type * bus, struct device * start,
76   int bus_for_each_drv(struct bus_type * bus, struct device_driver * start,
81 synchronized by taking the bus's lock (read currently). The reference
89 There is a top-level directory named 'bus'.
91 Each bus gets a directory in the bus directory, along with two default
94 	/sys/bus/pci/
95 	|-- devices
96 	`-- drivers
98 Drivers registered with the bus get a directory in the bus's drivers
101 	/sys/bus/pci/
102 	|-- devices
103 	`-- drivers
104 	    |-- Intel ICH
105 	    |-- Intel ICH Joystick
106 	    |-- agpgart
107 	    `-- e100
109 Each device that is discovered on a bus of that type gets a symlink in
110 the bus's devices directory to the device's directory in the physical
113 	/sys/bus/pci/
114 	|-- devices
115 	|   |-- 00:00.0 -> ../../../root/pci0/00:00.0
116 	|   |-- 00:01.0 -> ../../../root/pci0/00:01.0
117 	|   `-- 00:02.0 -> ../../../root/pci0/00:02.0
118 	`-- drivers
132 Bus drivers can export attributes using the BUS_ATTR_RW macro that works
142 This can then be used to add and remove the attribute from the bus's