Linux Kernel设备驱动模型之 struct bus_type

总线类型描述设备模型：

/** * struct bus_type - The bus type of the device * * @name: The name of the bus. * @dev_name: Used for subsystems to enumerate devices like ("foo%u", dev->id). * @dev_root: Default device to use as the parent. * @dev_attrs: Default attributes of the devices on the bus. * @bus_groups: Default attributes of the bus. * @dev_groups: Default attributes of the devices on the bus. * @drv_groups: Default attributes of the device drivers on the bus. * @match: Called, perhaps multiple times, whenever a new device or driver *  is added for this bus. It should return a positive value if the *  given device can be handled by the given driver and zero *  otherwise. It may also return error code if determining that *  the driver supports the device is not possible. In case of *  -EPROBE_DEFER it will queue the device for deferred probing. * @uevent: Called when a device is added, removed, or a few other things *  that generate uevents to add the environment variables. * @probe: Called when a new device or driver add to this bus, and callback *  the specific driver's probe to initial the matched device. * @remove: Called when a device removed from this bus. * @shutdown: Called at shut-down time to quiesce the device. * * @online: Called to put the device back online (after offlining it). * @offline: Called to put the device offline for hot-removal. May fail. * * @suspend: Called when a device on this bus wants to go to sleep mode. * @resume: Called to bring a device on this bus out of sleep mode. * @pm:  Power management operations of this bus, callback the specific *  device driver's pm-ops. * @iommu_ops:  IOMMU specific operations for this bus, used to attach IOMMU *              driver implementations to a bus and allow the driver to do *              bus-specific setup * @p:  The private data of the driver core, only the driver core can *  touch this. * @lock_key: Lock class key for use by the lock validator * * A bus is a channel between the processor and one or more devices. For the * purposes of the device model, all devices are connected via a bus, even if * it is an internal, virtual, "platform" bus. Buses can plug into each other. * A USB controller is usually a PCI device, for example. The device model * represents the actual connections between buses and the devices they control. * A bus is represented by the bus_type structure. It contains the name, the * default attributes, the bus' methods, PM operations, and the driver core's * private data. */struct bus_type { const char  *name; const char  *dev_name; struct device  *dev_root; struct device_attribute *dev_attrs; /* use dev_groups instead */ const struct attribute_group **bus_groups; const struct attribute_group **dev_groups; const struct attribute_group **drv_groups; int (*match)(struct device *dev, struct device_driver *drv); int (*uevent)(struct device *dev, struct kobj_uevent_env *env); int (*probe)(struct device *dev); int (*remove)(struct device *dev); void (*shutdown)(struct device *dev); int (*online)(struct device *dev); int (*offline)(struct device *dev); int (*suspend)(struct device *dev, pm_message_t state); int (*resume)(struct device *dev); const struct dev_pm_ops *pm; const struct iommu_ops *iommu_ops; struct subsys_private *p; struct lock_class_key lock_key;};