Linux那些事儿之我是Sysfs(5)举例二sculld

不妨再把sculld的代码也分析一下，先看初始函数

sculld_init()

-> register_ldd_driver()

->driver_register()

->bus_add_driver()

-> register_ldd_device()

->device_register()

->device_add()

->kobject_add()

->bus_add_device()

首先注册驱动，看bus_add_driver()

drivers/base/bus.c

int bus_add_driver(struct device_driver *drv)
{
	struct bus_type *bus;
	struct driver_private *priv;
	int error = 0;

	bus = bus_get(drv->bus);
	if (!bus)
		return -EINVAL;

	pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);

	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
	if (!priv) {
		error = -ENOMEM;
		goto out_put_bus;
	}
	klist_init(&priv->klist_devices, NULL, NULL);
	priv->driver = drv;
	drv->p = priv;
	priv->kobj.kset = bus->p->drivers_kset;
	error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
				     "%s", drv->name);
	if (error)
		goto out_unregister;

	klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
	if (drv->bus->p->drivers_autoprobe) {
		error = driver_attach(drv);
		if (error)
			goto out_unregister;
	}
	module_add_driver(drv->owner, drv);

	error = driver_create_file(drv, &driver_attr_uevent);
	if (error) {
		printk(KERN_ERR "%s: uevent attr (%s) failed\n",
			__func__, drv->name);
	}
	error = driver_add_groups(drv, bus->drv_groups);
	if (error) {
		/* How the hell do we get out of this pickle? Give up */
		printk(KERN_ERR "%s: driver_create_groups(%s) failed\n",
			__func__, drv->name);
	}

	if (!drv->suppress_bind_attrs) {
		error = add_bind_files(drv);
		if (error) {
			/* Ditto */
			printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
				__func__, drv->name);
		}
	}

	return 0;

out_unregister:
	kobject_put(&priv->kobj);
	kfree(drv->p);
	drv->p = NULL;
out_put_bus:
	bus_put(bus);
	return error;
}

kobject_init_and_add，把自己kobject链接到内核中去。

driver_attach(drv); 在总线中寻找，有没有设备可以让这个driver驱动。

drivers/base/dd.c

int driver_attach(struct device_driver *drv)
{
	return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
}

然后注册设备，

drivers/base/bus.c

int bus_add_device(struct device *dev)
{
	struct bus_type *bus = bus_get(dev->bus);
	int error = 0;

	if (bus) {
		pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
		error = device_add_attrs(bus, dev);
		if (error)
			goto out_put;
		error = device_add_groups(dev, bus->dev_groups);
		if (error)
			goto out_groups;
		error = sysfs_create_link(&bus->p->devices_kset->kobj,
						&dev->kobj, dev_name(dev));
		if (error)
			goto out_id;
		error = sysfs_create_link(&dev->kobj,
				&dev->bus->p->subsys.kobj, "subsystem");
		if (error)
			goto out_subsys;
		klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
	}
	return 0;

out_subsys:
	sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
out_groups:
	device_remove_groups(dev, bus->dev_groups);
out_id:
	device_remove_attrs(bus, dev);
out_put:
	bus_put(dev->bus);
	return error;
}

device_add_groups，把设备连入其总线的设备组中。

sysfs_create_link，创建了一个链接。

接下来进入sysfs部分。

人面不知何处去，桃花依旧笑春风。 唐·崔护·题都城南庄