三、设备的注册过程
当一个PCI设备热插拔，或是系统初启时，它会遍历这个总线的已经注册进内核里的驱动链表。当找到匹配的时候，它就将这个设备绑定。
它首先会执行一个注册函数：
int device_register(struct device *dev)
{
device_initialize(dev);
return device_add(dev);
}
int device_add(struct device *dev)
{
struct device *parent = NULL;
char *class_name = NULL;
struct class_interface *class_intf;
int error = -EINVAL;
dev = get_device(dev);
if (!dev || !strlen(dev->bus_id))
goto Error;
pr_debug("DEV: registering device: ID = '%s'\n", dev->bus_id);
parent = get_device(dev->parent);
error = setup_parent(dev, parent);
if (error)
goto Error;
/* first, register with generic layer. */
kobject_set_name(&dev->kobj, "%s", dev->bus_id);
error = kobject_add(&dev->kobj);
if (error)
goto Error;
/* notify platform of device entry */
if (platform_notify)
platform_notify(dev);
/* notify clients of device entry (new way) */
if (dev->bus) //通知链表
blocking_notifier_call_chain(&dev->bus->bus_notifier,
BUS_NOTIFY_ADD_DEVICE, dev);
dev->uevent_attr.attr.name = "uevent";
dev->uevent_attr.attr.mode = S_IWUSR;
if (dev->driver)
dev->uevent_attr.attr.owner = dev->driver->owner;
dev->uevent_attr.store = store_uevent;
error = device_create_file(dev, &dev->uevent_attr);
if (error)
goto attrError;
if (MAJOR(dev->devt)) { //属性处理
struct device_attribute *attr;
attr = kzalloc(sizeof(*attr), GFP_KERNEL);
if (!attr) {
error = -ENOMEM;
goto ueventattrError;
}
attr->attr.name = "dev";
attr->attr.mode = S_IRUGO;
if (dev->driver)
attr->attr.owner = dev->driver->owner;
attr->show = show_dev;
error = device_create_file(dev, attr);
if (error) {
kfree(attr);
goto ueventattrError;
}
dev->devt_attr = attr;
}
if (dev->class) { //设备类型处理
sysfs_create_link(&dev->kobj, &dev->class->subsys.kset.kobj,
"subsystem");
/* If this is not a "fake" compatible device, then create the
* symlink from the class to the device. */
if (dev->kobj.parent != &dev->class->subsys.kset.kobj)
sysfs_create_link(&dev->class->subsys.kset.kobj,
&dev->kobj, dev->bus_id);
if (parent) {
sysfs_create_link(&dev->kobj, &dev->parent->kobj,
"device");
#ifdef CONFIG_SYSFS_DEPRECATED
class_name = make_class_name(dev->class->name,
&dev->kobj);
if (class_name)
sysfs_create_link(&dev->parent->kobj,
&dev->kobj, class_name);
#endif
}
}
if ((error = device_add_attrs(dev)))
goto AttrsError;
if ((error = device_add_groups(dev)))
goto GroupError;
if ((error = device_pm_add(dev)))
goto PMError;
if ((error = bus_add_device(dev)))
goto BusError;
if (!dev->uevent_suppress)
kobject_uevent(&dev->kobj, KOBJ_ADD);
if ((error = bus_attach_device(dev))) //将设备于驱动绑定
goto AttachError;
if (parent) //加入链表
klist_add_tail(&dev->knode_parent, &parent->klist_children);
if (dev->class) {
down(&dev->class->sem);
/* tie the class to the device */
list_add_tail(&dev->node, &dev->class->devices);
/* notify any interfaces that the device is here */
list_for_each_entry(class_intf, &dev->class->interfaces, node)
if (class_intf->add_dev)
class_intf->add_dev(dev, class_intf);
up(&dev->class->sem);
}
Done:
kfree(class_name);
put_device(dev);
return error;
……
}
int bus_add_device(struct device * dev)
{
struct bus_type * bus = get_bus(dev->bus);
int error = 0;
if (bus) {
pr_debug("bus %s: add device %s\n", bus->name, dev->bus_id);
error = device_add_attrs(bus, dev);
if (error)
goto out_put;
error = sysfs_create_link(&bus->devices.kobj,
&dev->kobj, dev->bus_id);
if (error)
goto out_id;
error = sysfs_create_link(&dev->kobj,
&dev->bus->subsys.kset.kobj, "subsystem");
if (error)
goto out_subsys;
error = make_deprecated_bus_links(dev);
if (error)
goto out_deprecated;
}
return 0;
out_deprecated:
sysfs_remove_link(&dev->kobj, "subsystem");
out_subsys:
sysfs_remove_link(&bus->devices.kobj, dev->bus_id);
out_id:
device_remove_attrs(bus, dev);
out_put:
put_bus(dev->bus);
return error;
}
/**
* bus_attach_device - add device to bus
* @dev: device tried to attach to a driver
*
* - Add device to bus's list of devices.
* - Try to attach to driver.
*/
int bus_attach_device(struct device * dev)
{
struct bus_type *bus = dev->bus;
int ret = 0;
if (bus) {
dev->is_registered = 1;
ret = device_attach(dev);
if (ret >= 0) {
klist_add_tail(&dev->knode_bus, &bus->klist_devices);
ret = 0;
} else
dev->is_registered = 0;
}
return ret;
}
int device_attach(struct device * dev)
{
int ret = 0;
down(&dev->sem);
if (dev->driver) {
ret = device_bind_driver(dev);
if (ret == 0)
ret = 1;
} else
ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
up(&dev->sem);
return ret;
}
static int __device_attach(struct device_driver * drv, void * data)
{
struct device * dev = data;
return driver_probe_device(drv, dev);
}
接下来的代码就跟上面的驱动注册一样了。
声明：转的
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