diff --git a/drivers/base/class.c b/drivers/base/class.c
new file mode 100644
index 0000000..54def4e
--- /dev/null
+++ b/drivers/base/class.c
@@ -0,0 +1,580 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * class.c - basic device class management
+ *
+ * Copyright (c) 2002-3 Patrick Mochel
+ * Copyright (c) 2002-3 Open Source Development Labs
+ * Copyright (c) 2003-2004 Greg Kroah-Hartman
+ * Copyright (c) 2003-2004 IBM Corp.
+ */
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/kdev_t.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/genhd.h>
+#include <linux/mutex.h>
+#include "base.h"
+
+#define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)
+
+static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
+			       char *buf)
+{
+	struct class_attribute *class_attr = to_class_attr(attr);
+	struct subsys_private *cp = to_subsys_private(kobj);
+	ssize_t ret = -EIO;
+
+	if (class_attr->show)
+		ret = class_attr->show(cp->class, class_attr, buf);
+	return ret;
+}
+
+static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr,
+				const char *buf, size_t count)
+{
+	struct class_attribute *class_attr = to_class_attr(attr);
+	struct subsys_private *cp = to_subsys_private(kobj);
+	ssize_t ret = -EIO;
+
+	if (class_attr->store)
+		ret = class_attr->store(cp->class, class_attr, buf, count);
+	return ret;
+}
+
+static void class_release(struct kobject *kobj)
+{
+	struct subsys_private *cp = to_subsys_private(kobj);
+	struct class *class = cp->class;
+
+	pr_debug("class '%s': release.\n", class->name);
+
+	if (class->class_release)
+		class->class_release(class);
+	else
+		pr_debug("class '%s' does not have a release() function, "
+			 "be careful\n", class->name);
+
+	kfree(cp);
+}
+
+static const struct kobj_ns_type_operations *class_child_ns_type(struct kobject *kobj)
+{
+	struct subsys_private *cp = to_subsys_private(kobj);
+	struct class *class = cp->class;
+
+	return class->ns_type;
+}
+
+static const struct sysfs_ops class_sysfs_ops = {
+	.show	   = class_attr_show,
+	.store	   = class_attr_store,
+};
+
+static struct kobj_type class_ktype = {
+	.sysfs_ops	= &class_sysfs_ops,
+	.release	= class_release,
+	.child_ns_type	= class_child_ns_type,
+};
+
+/* Hotplug events for classes go to the class subsys */
+static struct kset *class_kset;
+
+
+int class_create_file_ns(struct class *cls, const struct class_attribute *attr,
+			 const void *ns)
+{
+	int error;
+
+	if (cls)
+		error = sysfs_create_file_ns(&cls->p->subsys.kobj,
+					     &attr->attr, ns);
+	else
+		error = -EINVAL;
+	return error;
+}
+
+void class_remove_file_ns(struct class *cls, const struct class_attribute *attr,
+			  const void *ns)
+{
+	if (cls)
+		sysfs_remove_file_ns(&cls->p->subsys.kobj, &attr->attr, ns);
+}
+
+static struct class *class_get(struct class *cls)
+{
+	if (cls)
+		kset_get(&cls->p->subsys);
+	return cls;
+}
+
+static void class_put(struct class *cls)
+{
+	if (cls)
+		kset_put(&cls->p->subsys);
+}
+
+static void klist_class_dev_get(struct klist_node *n)
+{
+	struct device *dev = container_of(n, struct device, knode_class);
+
+	get_device(dev);
+}
+
+static void klist_class_dev_put(struct klist_node *n)
+{
+	struct device *dev = container_of(n, struct device, knode_class);
+
+	put_device(dev);
+}
+
+static int class_add_groups(struct class *cls,
+			    const struct attribute_group **groups)
+{
+	return sysfs_create_groups(&cls->p->subsys.kobj, groups);
+}
+
+static void class_remove_groups(struct class *cls,
+				const struct attribute_group **groups)
+{
+	return sysfs_remove_groups(&cls->p->subsys.kobj, groups);
+}
+
+int __class_register(struct class *cls, struct lock_class_key *key)
+{
+	struct subsys_private *cp;
+	int error;
+
+	pr_debug("device class '%s': registering\n", cls->name);
+
+	cp = kzalloc(sizeof(*cp), GFP_KERNEL);
+	if (!cp)
+		return -ENOMEM;
+	klist_init(&cp->klist_devices, klist_class_dev_get, klist_class_dev_put);
+	INIT_LIST_HEAD(&cp->interfaces);
+	kset_init(&cp->glue_dirs);
+	__mutex_init(&cp->mutex, "subsys mutex", key);
+	error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name);
+	if (error) {
+		kfree(cp);
+		return error;
+	}
+
+	/* set the default /sys/dev directory for devices of this class */
+	if (!cls->dev_kobj)
+		cls->dev_kobj = sysfs_dev_char_kobj;
+
+#if defined(CONFIG_BLOCK)
+	/* let the block class directory show up in the root of sysfs */
+	if (!sysfs_deprecated || cls != &block_class)
+		cp->subsys.kobj.kset = class_kset;
+#else
+	cp->subsys.kobj.kset = class_kset;
+#endif
+	cp->subsys.kobj.ktype = &class_ktype;
+	cp->class = cls;
+	cls->p = cp;
+
+	error = kset_register(&cp->subsys);
+	if (error) {
+		kfree(cp);
+		return error;
+	}
+	error = class_add_groups(class_get(cls), cls->class_groups);
+	class_put(cls);
+	return error;
+}
+EXPORT_SYMBOL_GPL(__class_register);
+
+void class_unregister(struct class *cls)
+{
+	pr_debug("device class '%s': unregistering\n", cls->name);
+	class_remove_groups(cls, cls->class_groups);
+	kset_unregister(&cls->p->subsys);
+}
+
+static void class_create_release(struct class *cls)
+{
+	pr_debug("%s called for %s\n", __func__, cls->name);
+	kfree(cls);
+}
+
+/**
+ * class_create - create a struct class structure
+ * @owner: pointer to the module that is to "own" this struct class
+ * @name: pointer to a string for the name of this class.
+ * @key: the lock_class_key for this class; used by mutex lock debugging
+ *
+ * This is used to create a struct class pointer that can then be used
+ * in calls to device_create().
+ *
+ * Returns &struct class pointer on success, or ERR_PTR() on error.
+ *
+ * Note, the pointer created here is to be destroyed when finished by
+ * making a call to class_destroy().
+ */
+struct class *__class_create(struct module *owner, const char *name,
+			     struct lock_class_key *key)
+{
+	struct class *cls;
+	int retval;
+
+	cls = kzalloc(sizeof(*cls), GFP_KERNEL);
+	if (!cls) {
+		retval = -ENOMEM;
+		goto error;
+	}
+
+	cls->name = name;
+	cls->owner = owner;
+	cls->class_release = class_create_release;
+
+	retval = __class_register(cls, key);
+	if (retval)
+		goto error;
+
+	return cls;
+
+error:
+	kfree(cls);
+	return ERR_PTR(retval);
+}
+EXPORT_SYMBOL_GPL(__class_create);
+
+/**
+ * class_destroy - destroys a struct class structure
+ * @cls: pointer to the struct class that is to be destroyed
+ *
+ * Note, the pointer to be destroyed must have been created with a call
+ * to class_create().
+ */
+void class_destroy(struct class *cls)
+{
+	if ((cls == NULL) || (IS_ERR(cls)))
+		return;
+
+	class_unregister(cls);
+}
+
+/**
+ * class_dev_iter_init - initialize class device iterator
+ * @iter: class iterator to initialize
+ * @class: the class we wanna iterate over
+ * @start: the device to start iterating from, if any
+ * @type: device_type of the devices to iterate over, NULL for all
+ *
+ * Initialize class iterator @iter such that it iterates over devices
+ * of @class.  If @start is set, the list iteration will start there,
+ * otherwise if it is NULL, the iteration starts at the beginning of
+ * the list.
+ */
+void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
+			 struct device *start, const struct device_type *type)
+{
+	struct klist_node *start_knode = NULL;
+
+	if (start)
+		start_knode = &start->knode_class;
+	klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
+	iter->type = type;
+}
+EXPORT_SYMBOL_GPL(class_dev_iter_init);
+
+/**
+ * class_dev_iter_next - iterate to the next device
+ * @iter: class iterator to proceed
+ *
+ * Proceed @iter to the next device and return it.  Returns NULL if
+ * iteration is complete.
+ *
+ * The returned device is referenced and won't be released till
+ * iterator is proceed to the next device or exited.  The caller is
+ * free to do whatever it wants to do with the device including
+ * calling back into class code.
+ */
+struct device *class_dev_iter_next(struct class_dev_iter *iter)
+{
+	struct klist_node *knode;
+	struct device *dev;
+
+	while (1) {
+		knode = klist_next(&iter->ki);
+		if (!knode)
+			return NULL;
+		dev = container_of(knode, struct device, knode_class);
+		if (!iter->type || iter->type == dev->type)
+			return dev;
+	}
+}
+EXPORT_SYMBOL_GPL(class_dev_iter_next);
+
+/**
+ * class_dev_iter_exit - finish iteration
+ * @iter: class iterator to finish
+ *
+ * Finish an iteration.  Always call this function after iteration is
+ * complete whether the iteration ran till the end or not.
+ */
+void class_dev_iter_exit(struct class_dev_iter *iter)
+{
+	klist_iter_exit(&iter->ki);
+}
+EXPORT_SYMBOL_GPL(class_dev_iter_exit);
+
+/**
+ * class_for_each_device - device iterator
+ * @class: the class we're iterating
+ * @start: the device to start with in the list, if any.
+ * @data: data for the callback
+ * @fn: function to be called for each device
+ *
+ * Iterate over @class's list of devices, and call @fn for each,
+ * passing it @data.  If @start is set, the list iteration will start
+ * there, otherwise if it is NULL, the iteration starts at the
+ * beginning of the list.
+ *
+ * We check the return of @fn each time. If it returns anything
+ * other than 0, we break out and return that value.
+ *
+ * @fn is allowed to do anything including calling back into class
+ * code.  There's no locking restriction.
+ */
+int class_for_each_device(struct class *class, struct device *start,
+			  void *data, int (*fn)(struct device *, void *))
+{
+	struct class_dev_iter iter;
+	struct device *dev;
+	int error = 0;
+
+	if (!class)
+		return -EINVAL;
+	if (!class->p) {
+		WARN(1, "%s called for class '%s' before it was initialized",
+		     __func__, class->name);
+		return -EINVAL;
+	}
+
+	class_dev_iter_init(&iter, class, start, NULL);
+	while ((dev = class_dev_iter_next(&iter))) {
+		error = fn(dev, data);
+		if (error)
+			break;
+	}
+	class_dev_iter_exit(&iter);
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(class_for_each_device);
+
+/**
+ * class_find_device - device iterator for locating a particular device
+ * @class: the class we're iterating
+ * @start: Device to begin with
+ * @data: data for the match function
+ * @match: function to check device
+ *
+ * This is similar to the class_for_each_dev() function above, but it
+ * returns a reference to a device that is 'found' for later use, as
+ * determined by the @match callback.
+ *
+ * The callback should return 0 if the device doesn't match and non-zero
+ * if it does.  If the callback returns non-zero, this function will
+ * return to the caller and not iterate over any more devices.
+ *
+ * Note, you will need to drop the reference with put_device() after use.
+ *
+ * @match is allowed to do anything including calling back into class
+ * code.  There's no locking restriction.
+ */
+struct device *class_find_device(struct class *class, struct device *start,
+				 const void *data,
+				 int (*match)(struct device *, const void *))
+{
+	struct class_dev_iter iter;
+	struct device *dev;
+
+	if (!class)
+		return NULL;
+	if (!class->p) {
+		WARN(1, "%s called for class '%s' before it was initialized",
+		     __func__, class->name);
+		return NULL;
+	}
+
+	class_dev_iter_init(&iter, class, start, NULL);
+	while ((dev = class_dev_iter_next(&iter))) {
+		if (match(dev, data)) {
+			get_device(dev);
+			break;
+		}
+	}
+	class_dev_iter_exit(&iter);
+
+	return dev;
+}
+EXPORT_SYMBOL_GPL(class_find_device);
+
+int class_interface_register(struct class_interface *class_intf)
+{
+	struct class *parent;
+	struct class_dev_iter iter;
+	struct device *dev;
+
+	if (!class_intf || !class_intf->class)
+		return -ENODEV;
+
+	parent = class_get(class_intf->class);
+	if (!parent)
+		return -EINVAL;
+
+	mutex_lock(&parent->p->mutex);
+	list_add_tail(&class_intf->node, &parent->p->interfaces);
+	if (class_intf->add_dev) {
+		class_dev_iter_init(&iter, parent, NULL, NULL);
+		while ((dev = class_dev_iter_next(&iter)))
+			class_intf->add_dev(dev, class_intf);
+		class_dev_iter_exit(&iter);
+	}
+	mutex_unlock(&parent->p->mutex);
+
+	return 0;
+}
+
+void class_interface_unregister(struct class_interface *class_intf)
+{
+	struct class *parent = class_intf->class;
+	struct class_dev_iter iter;
+	struct device *dev;
+
+	if (!parent)
+		return;
+
+	mutex_lock(&parent->p->mutex);
+	list_del_init(&class_intf->node);
+	if (class_intf->remove_dev) {
+		class_dev_iter_init(&iter, parent, NULL, NULL);
+		while ((dev = class_dev_iter_next(&iter)))
+			class_intf->remove_dev(dev, class_intf);
+		class_dev_iter_exit(&iter);
+	}
+	mutex_unlock(&parent->p->mutex);
+
+	class_put(parent);
+}
+
+ssize_t show_class_attr_string(struct class *class,
+			       struct class_attribute *attr, char *buf)
+{
+	struct class_attribute_string *cs;
+
+	cs = container_of(attr, struct class_attribute_string, attr);
+	return snprintf(buf, PAGE_SIZE, "%s\n", cs->str);
+}
+
+EXPORT_SYMBOL_GPL(show_class_attr_string);
+
+struct class_compat {
+	struct kobject *kobj;
+};
+
+/**
+ * class_compat_register - register a compatibility class
+ * @name: the name of the class
+ *
+ * Compatibility class are meant as a temporary user-space compatibility
+ * workaround when converting a family of class devices to a bus devices.
+ */
+struct class_compat *class_compat_register(const char *name)
+{
+	struct class_compat *cls;
+
+	cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
+	if (!cls)
+		return NULL;
+	cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
+	if (!cls->kobj) {
+		kfree(cls);
+		return NULL;
+	}
+	return cls;
+}
+EXPORT_SYMBOL_GPL(class_compat_register);
+
+/**
+ * class_compat_unregister - unregister a compatibility class
+ * @cls: the class to unregister
+ */
+void class_compat_unregister(struct class_compat *cls)
+{
+	kobject_put(cls->kobj);
+	kfree(cls);
+}
+EXPORT_SYMBOL_GPL(class_compat_unregister);
+
+/**
+ * class_compat_create_link - create a compatibility class device link to
+ *			      a bus device
+ * @cls: the compatibility class
+ * @dev: the target bus device
+ * @device_link: an optional device to which a "device" link should be created
+ */
+int class_compat_create_link(struct class_compat *cls, struct device *dev,
+			     struct device *device_link)
+{
+	int error;
+
+	error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
+	if (error)
+		return error;
+
+	/*
+	 * Optionally add a "device" link (typically to the parent), as a
+	 * class device would have one and we want to provide as much
+	 * backwards compatibility as possible.
+	 */
+	if (device_link) {
+		error = sysfs_create_link(&dev->kobj, &device_link->kobj,
+					  "device");
+		if (error)
+			sysfs_remove_link(cls->kobj, dev_name(dev));
+	}
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(class_compat_create_link);
+
+/**
+ * class_compat_remove_link - remove a compatibility class device link to
+ *			      a bus device
+ * @cls: the compatibility class
+ * @dev: the target bus device
+ * @device_link: an optional device to which a "device" link was previously
+ * 		 created
+ */
+void class_compat_remove_link(struct class_compat *cls, struct device *dev,
+			      struct device *device_link)
+{
+	if (device_link)
+		sysfs_remove_link(&dev->kobj, "device");
+	sysfs_remove_link(cls->kobj, dev_name(dev));
+}
+EXPORT_SYMBOL_GPL(class_compat_remove_link);
+
+int __init classes_init(void)
+{
+	class_kset = kset_create_and_add("class", NULL, NULL);
+	if (!class_kset)
+		return -ENOMEM;
+	return 0;
+}
+
+EXPORT_SYMBOL_GPL(class_create_file_ns);
+EXPORT_SYMBOL_GPL(class_remove_file_ns);
+EXPORT_SYMBOL_GPL(class_unregister);
+EXPORT_SYMBOL_GPL(class_destroy);
+
+EXPORT_SYMBOL_GPL(class_interface_register);
+EXPORT_SYMBOL_GPL(class_interface_unregister);