linux 总线 和 总线设备本身

jieao111

This pci_bus_type variable is registered with the driver core when the PCI subsystem is loaded in the kernel with a call to bus_register

jieao111

We have seen how the lddbus code registers its bus type. However, an actual bus is a device and must be registered separately. For simplicity, the lddbus module supports only a single virtual bus, so the driver sets up its device at compile time:

static void ldd_bus_release(struct device *dev)

{

    printk(KERN_DEBUG "lddbus release\n");

}

   

struct device ldd_bus = {

    .bus_id   = "ldd0",

    .release  = ldd_bus_release

};


This is a top-level bus, so the parent and bus fields are left NULL. We have a simple, no-op release method, and, as the first (and only) bus, its name is ldd0. This bus device is registered with:

ret = device_register(&ldd_bus);

if (ret)

    printk(KERN_NOTICE "Unable to register ldd0\n");


Once that call is complete, the new bus can be seen under /sys/devices in sysfs. Any devices added to this bus then shows up under /sys/devices/ldd0/.

jieao111

这个一个bus是一个device（即这个bus结构体内也有device这个成员），而这个bus的结构体内有bus_type这个成员，所以注册的时候就联系一起了。