Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 4424 insertions, 0 deletions

diff --git a/drivers/base/core.c b/drivers/base/core.c
new file mode 100644
index 000000000..d98cab88c
--- /dev/null
+++ b/drivers/base/core.c
@@ -0,0 +1,4424 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * drivers/base/core.c - core driver model code (device registration, etc)
+ *
+ * Copyright (c) 2002-3 Patrick Mochel
+ * Copyright (c) 2002-3 Open Source Development Labs
+ * Copyright (c) 2006 Greg Kroah-Hartman <gregkh@suse.de>
+ * Copyright (c) 2006 Novell, Inc.
+ */
+
+#include <linux/acpi.h>
+#include <linux/cpufreq.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/fwnode.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/kdev_t.h>
+#include <linux/notifier.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/genhd.h>
+#include <linux/mutex.h>
+#include <linux/pm_runtime.h>
+#include <linux/netdevice.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/mm.h>
+#include <linux/sysfs.h>
+
+#include "base.h"
+#include "power/power.h"
+
+#ifdef CONFIG_SYSFS_DEPRECATED
+#ifdef CONFIG_SYSFS_DEPRECATED_V2
+long sysfs_deprecated = 1;
+#else
+long sysfs_deprecated = 0;
+#endif
+static int __init sysfs_deprecated_setup(char *arg)
+{
+	return kstrtol(arg, 10, &sysfs_deprecated);
+}
+early_param("sysfs.deprecated", sysfs_deprecated_setup);
+#endif
+
+/* Device links support. */
+static LIST_HEAD(wait_for_suppliers);
+static DEFINE_MUTEX(wfs_lock);
+static LIST_HEAD(deferred_sync);
+static unsigned int defer_sync_state_count = 1;
+static unsigned int defer_fw_devlink_count;
+static LIST_HEAD(deferred_fw_devlink);
+static DEFINE_MUTEX(defer_fw_devlink_lock);
+static bool fw_devlink_is_permissive(void);
+
+#ifdef CONFIG_SRCU
+static DEFINE_MUTEX(device_links_lock);
+DEFINE_STATIC_SRCU(device_links_srcu);
+
+static inline void device_links_write_lock(void)
+{
+	mutex_lock(&device_links_lock);
+}
+
+static inline void device_links_write_unlock(void)
+{
+	mutex_unlock(&device_links_lock);
+}
+
+int device_links_read_lock(void) __acquires(&device_links_srcu)
+{
+	return srcu_read_lock(&device_links_srcu);
+}
+
+void device_links_read_unlock(int idx) __releases(&device_links_srcu)
+{
+	srcu_read_unlock(&device_links_srcu, idx);
+}
+
+int device_links_read_lock_held(void)
+{
+	return srcu_read_lock_held(&device_links_srcu);
+}
+
+static void device_link_synchronize_removal(void)
+{
+	synchronize_srcu(&device_links_srcu);
+}
+#else /* !CONFIG_SRCU */
+static DECLARE_RWSEM(device_links_lock);
+
+static inline void device_links_write_lock(void)
+{
+	down_write(&device_links_lock);
+}
+
+static inline void device_links_write_unlock(void)
+{
+	up_write(&device_links_lock);
+}
+
+int device_links_read_lock(void)
+{
+	down_read(&device_links_lock);
+	return 0;
+}
+
+void device_links_read_unlock(int not_used)
+{
+	up_read(&device_links_lock);
+}
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+int device_links_read_lock_held(void)
+{
+	return lockdep_is_held(&device_links_lock);
+}
+#endif
+
+static inline void device_link_synchronize_removal(void)
+{
+}
+#endif /* !CONFIG_SRCU */
+
+static bool device_is_ancestor(struct device *dev, struct device *target)
+{
+	while (target->parent) {
+		target = target->parent;
+		if (dev == target)
+			return true;
+	}
+	return false;
+}
+
+/**
+ * device_is_dependent - Check if one device depends on another one
+ * @dev: Device to check dependencies for.
+ * @target: Device to check against.
+ *
+ * Check if @target depends on @dev or any device dependent on it (its child or
+ * its consumer etc).  Return 1 if that is the case or 0 otherwise.
+ */
+int device_is_dependent(struct device *dev, void *target)
+{
+	struct device_link *link;
+	int ret;
+
+	/*
+	 * The "ancestors" check is needed to catch the case when the target
+	 * device has not been completely initialized yet and it is still
+	 * missing from the list of children of its parent device.
+	 */
+	if (dev == target || device_is_ancestor(dev, target))
+		return 1;
+
+	ret = device_for_each_child(dev, target, device_is_dependent);
+	if (ret)
+		return ret;
+
+	list_for_each_entry(link, &dev->links.consumers, s_node) {
+		if (link->flags == (DL_FLAG_SYNC_STATE_ONLY | DL_FLAG_MANAGED))
+			continue;
+
+		if (link->consumer == target)
+			return 1;
+
+		ret = device_is_dependent(link->consumer, target);
+		if (ret)
+			break;
+	}
+	return ret;
+}
+
+static void device_link_init_status(struct device_link *link,
+				    struct device *consumer,
+				    struct device *supplier)
+{
+	switch (supplier->links.status) {
+	case DL_DEV_PROBING:
+		switch (consumer->links.status) {
+		case DL_DEV_PROBING:
+			/*
+			 * A consumer driver can create a link to a supplier
+			 * that has not completed its probing yet as long as it
+			 * knows that the supplier is already functional (for
+			 * example, it has just acquired some resources from the
+			 * supplier).
+			 */
+			link->status = DL_STATE_CONSUMER_PROBE;
+			break;
+		default:
+			link->status = DL_STATE_DORMANT;
+			break;
+		}
+		break;
+	case DL_DEV_DRIVER_BOUND:
+		switch (consumer->links.status) {
+		case DL_DEV_PROBING:
+			link->status = DL_STATE_CONSUMER_PROBE;
+			break;
+		case DL_DEV_DRIVER_BOUND:
+			link->status = DL_STATE_ACTIVE;
+			break;
+		default:
+			link->status = DL_STATE_AVAILABLE;
+			break;
+		}
+		break;
+	case DL_DEV_UNBINDING:
+		link->status = DL_STATE_SUPPLIER_UNBIND;
+		break;
+	default:
+		link->status = DL_STATE_DORMANT;
+		break;
+	}
+}
+
+static int device_reorder_to_tail(struct device *dev, void *not_used)
+{
+	struct device_link *link;
+
+	/*
+	 * Devices that have not been registered yet will be put to the ends
+	 * of the lists during the registration, so skip them here.
+	 */
+	if (device_is_registered(dev))
+		devices_kset_move_last(dev);
+
+	if (device_pm_initialized(dev))
+		device_pm_move_last(dev);
+
+	device_for_each_child(dev, NULL, device_reorder_to_tail);
+	list_for_each_entry(link, &dev->links.consumers, s_node) {
+		if (link->flags == (DL_FLAG_SYNC_STATE_ONLY | DL_FLAG_MANAGED))
+			continue;
+		device_reorder_to_tail(link->consumer, NULL);
+	}
+
+	return 0;
+}
+
+/**
+ * device_pm_move_to_tail - Move set of devices to the end of device lists
+ * @dev: Device to move
+ *
+ * This is a device_reorder_to_tail() wrapper taking the requisite locks.
+ *
+ * It moves the @dev along with all of its children and all of its consumers
+ * to the ends of the device_kset and dpm_list, recursively.
+ */
+void device_pm_move_to_tail(struct device *dev)
+{
+	int idx;
+
+	idx = device_links_read_lock();
+	device_pm_lock();
+	device_reorder_to_tail(dev, NULL);
+	device_pm_unlock();
+	device_links_read_unlock(idx);
+}
+
+#define to_devlink(dev)	container_of((dev), struct device_link, link_dev)
+
+static ssize_t status_show(struct device *dev,
+			   struct device_attribute *attr, char *buf)
+{
+	const char *output;
+
+	switch (to_devlink(dev)->status) {
+	case DL_STATE_NONE:
+		output = "not tracked";
+		break;
+	case DL_STATE_DORMANT:
+		output = "dormant";
+		break;
+	case DL_STATE_AVAILABLE:
+		output = "available";
+		break;
+	case DL_STATE_CONSUMER_PROBE:
+		output = "consumer probing";
+		break;
+	case DL_STATE_ACTIVE:
+		output = "active";
+		break;
+	case DL_STATE_SUPPLIER_UNBIND:
+		output = "supplier unbinding";
+		break;
+	default:
+		output = "unknown";
+		break;
+	}
+
+	return sysfs_emit(buf, "%s\n", output);
+}
+static DEVICE_ATTR_RO(status);
+
+static ssize_t auto_remove_on_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct device_link *link = to_devlink(dev);
+	const char *output;
+
+	if (link->flags & DL_FLAG_AUTOREMOVE_SUPPLIER)
+		output = "supplier unbind";
+	else if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER)
+		output = "consumer unbind";
+	else
+		output = "never";
+
+	return sysfs_emit(buf, "%s\n", output);
+}
+static DEVICE_ATTR_RO(auto_remove_on);
+
+static ssize_t runtime_pm_show(struct device *dev,
+			       struct device_attribute *attr, char *buf)
+{
+	struct device_link *link = to_devlink(dev);
+
+	return sysfs_emit(buf, "%d\n", !!(link->flags & DL_FLAG_PM_RUNTIME));
+}
+static DEVICE_ATTR_RO(runtime_pm);
+
+static ssize_t sync_state_only_show(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	struct device_link *link = to_devlink(dev);
+
+	return sysfs_emit(buf, "%d\n",
+			  !!(link->flags & DL_FLAG_SYNC_STATE_ONLY));
+}
+static DEVICE_ATTR_RO(sync_state_only);
+
+static struct attribute *devlink_attrs[] = {
+	&dev_attr_status.attr,
+	&dev_attr_auto_remove_on.attr,
+	&dev_attr_runtime_pm.attr,
+	&dev_attr_sync_state_only.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(devlink);
+
+static void device_link_release_fn(struct work_struct *work)
+{
+	struct device_link *link = container_of(work, struct device_link, rm_work);
+
+	/* Ensure that all references to the link object have been dropped. */
+	device_link_synchronize_removal();
+
+	pm_runtime_release_supplier(link);
+	pm_request_idle(link->supplier);
+
+	put_device(link->consumer);
+	put_device(link->supplier);
+	kfree(link);
+}
+
+static void devlink_dev_release(struct device *dev)
+{
+	struct device_link *link = to_devlink(dev);
+
+	INIT_WORK(&link->rm_work, device_link_release_fn);
+	/*
+	 * It may take a while to complete this work because of the SRCU
+	 * synchronization in device_link_release_fn() and if the consumer or
+	 * supplier devices get deleted when it runs, so put it into the "long"
+	 * workqueue.
+	 */
+	queue_work(system_long_wq, &link->rm_work);
+}
+
+static struct class devlink_class = {
+	.name = "devlink",
+	.owner = THIS_MODULE,
+	.dev_groups = devlink_groups,
+	.dev_release = devlink_dev_release,
+};
+
+static int devlink_add_symlinks(struct device *dev,
+				struct class_interface *class_intf)
+{
+	int ret;
+	size_t len;
+	struct device_link *link = to_devlink(dev);
+	struct device *sup = link->supplier;
+	struct device *con = link->consumer;
+	char *buf;
+
+	len = max(strlen(dev_bus_name(sup)) + strlen(dev_name(sup)),
+		  strlen(dev_bus_name(con)) + strlen(dev_name(con)));
+	len += strlen(":");
+	len += strlen("supplier:") + 1;
+	buf = kzalloc(len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = sysfs_create_link(&link->link_dev.kobj, &sup->kobj, "supplier");
+	if (ret)
+		goto out;
+
+	ret = sysfs_create_link(&link->link_dev.kobj, &con->kobj, "consumer");
+	if (ret)
+		goto err_con;
+
+	snprintf(buf, len, "consumer:%s:%s", dev_bus_name(con), dev_name(con));
+	ret = sysfs_create_link(&sup->kobj, &link->link_dev.kobj, buf);
+	if (ret)
+		goto err_con_dev;
+
+	snprintf(buf, len, "supplier:%s:%s", dev_bus_name(sup), dev_name(sup));
+	ret = sysfs_create_link(&con->kobj, &link->link_dev.kobj, buf);
+	if (ret)
+		goto err_sup_dev;
+
+	goto out;
+
+err_sup_dev:
+	snprintf(buf, len, "consumer:%s:%s", dev_bus_name(con), dev_name(con));
+	sysfs_remove_link(&sup->kobj, buf);
+err_con_dev:
+	sysfs_remove_link(&link->link_dev.kobj, "consumer");
+err_con:
+	sysfs_remove_link(&link->link_dev.kobj, "supplier");
+out:
+	kfree(buf);
+	return ret;
+}
+
+static void devlink_remove_symlinks(struct device *dev,
+				   struct class_interface *class_intf)
+{
+	struct device_link *link = to_devlink(dev);
+	size_t len;
+	struct device *sup = link->supplier;
+	struct device *con = link->consumer;
+	char *buf;
+
+	sysfs_remove_link(&link->link_dev.kobj, "consumer");
+	sysfs_remove_link(&link->link_dev.kobj, "supplier");
+
+	len = max(strlen(dev_bus_name(sup)) + strlen(dev_name(sup)),
+		  strlen(dev_bus_name(con)) + strlen(dev_name(con)));
+	len += strlen(":");
+	len += strlen("supplier:") + 1;
+	buf = kzalloc(len, GFP_KERNEL);
+	if (!buf) {
+		WARN(1, "Unable to properly free device link symlinks!\n");
+		return;
+	}
+
+	if (device_is_registered(con)) {
+		snprintf(buf, len, "supplier:%s:%s", dev_bus_name(sup), dev_name(sup));
+		sysfs_remove_link(&con->kobj, buf);
+	}
+	snprintf(buf, len, "consumer:%s:%s", dev_bus_name(con), dev_name(con));
+	sysfs_remove_link(&sup->kobj, buf);
+	kfree(buf);
+}
+
+static struct class_interface devlink_class_intf = {
+	.class = &devlink_class,
+	.add_dev = devlink_add_symlinks,
+	.remove_dev = devlink_remove_symlinks,
+};
+
+static int __init devlink_class_init(void)
+{
+	int ret;
+
+	ret = class_register(&devlink_class);
+	if (ret)
+		return ret;
+
+	ret = class_interface_register(&devlink_class_intf);
+	if (ret)
+		class_unregister(&devlink_class);
+
+	return ret;
+}
+postcore_initcall(devlink_class_init);
+
+#define DL_MANAGED_LINK_FLAGS (DL_FLAG_AUTOREMOVE_CONSUMER | \
+			       DL_FLAG_AUTOREMOVE_SUPPLIER | \
+			       DL_FLAG_AUTOPROBE_CONSUMER  | \
+			       DL_FLAG_SYNC_STATE_ONLY)
+
+#define DL_ADD_VALID_FLAGS (DL_MANAGED_LINK_FLAGS | DL_FLAG_STATELESS | \
+			    DL_FLAG_PM_RUNTIME | DL_FLAG_RPM_ACTIVE)
+
+/**
+ * device_link_add - Create a link between two devices.
+ * @consumer: Consumer end of the link.
+ * @supplier: Supplier end of the link.
+ * @flags: Link flags.
+ *
+ * The caller is responsible for the proper synchronization of the link creation
+ * with runtime PM.  First, setting the DL_FLAG_PM_RUNTIME flag will cause the
+ * runtime PM framework to take the link into account.  Second, if the
+ * DL_FLAG_RPM_ACTIVE flag is set in addition to it, the supplier devices will
+ * be forced into the active metastate and reference-counted upon the creation
+ * of the link.  If DL_FLAG_PM_RUNTIME is not set, DL_FLAG_RPM_ACTIVE will be
+ * ignored.
+ *
+ * If DL_FLAG_STATELESS is set in @flags, the caller of this function is
+ * expected to release the link returned by it directly with the help of either
+ * device_link_del() or device_link_remove().
+ *
+ * If that flag is not set, however, the caller of this function is handing the
+ * management of the link over to the driver core entirely and its return value
+ * can only be used to check whether or not the link is present.  In that case,
+ * the DL_FLAG_AUTOREMOVE_CONSUMER and DL_FLAG_AUTOREMOVE_SUPPLIER device link
+ * flags can be used to indicate to the driver core when the link can be safely
+ * deleted.  Namely, setting one of them in @flags indicates to the driver core
+ * that the link is not going to be used (by the given caller of this function)
+ * after unbinding the consumer or supplier driver, respectively, from its
+ * device, so the link can be deleted at that point.  If none of them is set,
+ * the link will be maintained until one of the devices pointed to by it (either
+ * the consumer or the supplier) is unregistered.
+ *
+ * Also, if DL_FLAG_STATELESS, DL_FLAG_AUTOREMOVE_CONSUMER and
+ * DL_FLAG_AUTOREMOVE_SUPPLIER are not set in @flags (that is, a persistent
+ * managed device link is being added), the DL_FLAG_AUTOPROBE_CONSUMER flag can
+ * be used to request the driver core to automaticall probe for a consmer
+ * driver after successfully binding a driver to the supplier device.
+ *
+ * The combination of DL_FLAG_STATELESS and one of DL_FLAG_AUTOREMOVE_CONSUMER,
+ * DL_FLAG_AUTOREMOVE_SUPPLIER, or DL_FLAG_AUTOPROBE_CONSUMER set in @flags at
+ * the same time is invalid and will cause NULL to be returned upfront.
+ * However, if a device link between the given @consumer and @supplier pair
+ * exists already when this function is called for them, the existing link will
+ * be returned regardless of its current type and status (the link's flags may
+ * be modified then).  The caller of this function is then expected to treat
+ * the link as though it has just been created, so (in particular) if
+ * DL_FLAG_STATELESS was passed in @flags, the link needs to be released
+ * explicitly when not needed any more (as stated above).
+ *
+ * A side effect of the link creation is re-ordering of dpm_list and the
+ * devices_kset list by moving the consumer device and all devices depending
+ * on it to the ends of these lists (that does not happen to devices that have
+ * not been registered when this function is called).
+ *
+ * The supplier device is required to be registered when this function is called
+ * and NULL will be returned if that is not the case.  The consumer device need
+ * not be registered, however.
+ */
+struct device_link *device_link_add(struct device *consumer,
+				    struct device *supplier, u32 flags)
+{
+	struct device_link *link;
+
+	if (!consumer || !supplier || consumer == supplier ||
+	    flags & ~DL_ADD_VALID_FLAGS ||
+	    (flags & DL_FLAG_STATELESS && flags & DL_MANAGED_LINK_FLAGS) ||
+	    (flags & DL_FLAG_SYNC_STATE_ONLY &&
+	     flags != DL_FLAG_SYNC_STATE_ONLY) ||
+	    (flags & DL_FLAG_AUTOPROBE_CONSUMER &&
+	     flags & (DL_FLAG_AUTOREMOVE_CONSUMER |
+		      DL_FLAG_AUTOREMOVE_SUPPLIER)))
+		return NULL;
+
+	if (flags & DL_FLAG_PM_RUNTIME && flags & DL_FLAG_RPM_ACTIVE) {
+		if (pm_runtime_get_sync(supplier) < 0) {
+			pm_runtime_put_noidle(supplier);
+			return NULL;
+		}
+	}
+
+	if (!(flags & DL_FLAG_STATELESS))
+		flags |= DL_FLAG_MANAGED;
+
+	device_links_write_lock();
+	device_pm_lock();
+
+	/*
+	 * If the supplier has not been fully registered yet or there is a
+	 * reverse (non-SYNC_STATE_ONLY) dependency between the consumer and
+	 * the supplier already in the graph, return NULL. If the link is a
+	 * SYNC_STATE_ONLY link, we don't check for reverse dependencies
+	 * because it only affects sync_state() callbacks.
+	 */
+	if (!device_pm_initialized(supplier)
+	    || (!(flags & DL_FLAG_SYNC_STATE_ONLY) &&
+		  device_is_dependent(consumer, supplier))) {
+		link = NULL;
+		goto out;
+	}
+
+	/*
+	 * DL_FLAG_AUTOREMOVE_SUPPLIER indicates that the link will be needed
+	 * longer than for DL_FLAG_AUTOREMOVE_CONSUMER and setting them both
+	 * together doesn't make sense, so prefer DL_FLAG_AUTOREMOVE_SUPPLIER.
+	 */
+	if (flags & DL_FLAG_AUTOREMOVE_SUPPLIER)
+		flags &= ~DL_FLAG_AUTOREMOVE_CONSUMER;
+
+	list_for_each_entry(link, &supplier->links.consumers, s_node) {
+		if (link->consumer != consumer)
+			continue;
+
+		if (flags & DL_FLAG_PM_RUNTIME) {
+			if (!(link->flags & DL_FLAG_PM_RUNTIME)) {
+				pm_runtime_new_link(consumer);
+				link->flags |= DL_FLAG_PM_RUNTIME;
+			}
+			if (flags & DL_FLAG_RPM_ACTIVE)
+				refcount_inc(&link->rpm_active);
+		}
+
+		if (flags & DL_FLAG_STATELESS) {
+			kref_get(&link->kref);
+			if (link->flags & DL_FLAG_SYNC_STATE_ONLY &&
+			    !(link->flags & DL_FLAG_STATELESS)) {
+				link->flags |= DL_FLAG_STATELESS;
+				goto reorder;
+			} else {
+				link->flags |= DL_FLAG_STATELESS;
+				goto out;
+			}
+		}
+
+		/*
+		 * If the life time of the link following from the new flags is
+		 * longer than indicated by the flags of the existing link,
+		 * update the existing link to stay around longer.
+		 */
+		if (flags & DL_FLAG_AUTOREMOVE_SUPPLIER) {
+			if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER) {
+				link->flags &= ~DL_FLAG_AUTOREMOVE_CONSUMER;
+				link->flags |= DL_FLAG_AUTOREMOVE_SUPPLIER;
+			}
+		} else if (!(flags & DL_FLAG_AUTOREMOVE_CONSUMER)) {
+			link->flags &= ~(DL_FLAG_AUTOREMOVE_CONSUMER |
+					 DL_FLAG_AUTOREMOVE_SUPPLIER);
+		}
+		if (!(link->flags & DL_FLAG_MANAGED)) {
+			kref_get(&link->kref);
+			link->flags |= DL_FLAG_MANAGED;
+			device_link_init_status(link, consumer, supplier);
+		}
+		if (link->flags & DL_FLAG_SYNC_STATE_ONLY &&
+		    !(flags & DL_FLAG_SYNC_STATE_ONLY)) {
+			link->flags &= ~DL_FLAG_SYNC_STATE_ONLY;
+			goto reorder;
+		}
+
+		goto out;
+	}
+
+	link = kzalloc(sizeof(*link), GFP_KERNEL);
+	if (!link)
+		goto out;
+
+	refcount_set(&link->rpm_active, 1);
+
+	get_device(supplier);
+	link->supplier = supplier;
+	INIT_LIST_HEAD(&link->s_node);
+	get_device(consumer);
+	link->consumer = consumer;
+	INIT_LIST_HEAD(&link->c_node);
+	link->flags = flags;
+	kref_init(&link->kref);
+
+	link->link_dev.class = &devlink_class;
+	device_set_pm_not_required(&link->link_dev);
+	dev_set_name(&link->link_dev, "%s:%s--%s:%s",
+		     dev_bus_name(supplier), dev_name(supplier),
+		     dev_bus_name(consumer), dev_name(consumer));
+	if (device_register(&link->link_dev)) {
+		put_device(&link->link_dev);
+		link = NULL;
+		goto out;
+	}
+
+	if (flags & DL_FLAG_PM_RUNTIME) {
+		if (flags & DL_FLAG_RPM_ACTIVE)
+			refcount_inc(&link->rpm_active);
+
+		pm_runtime_new_link(consumer);
+	}
+
+	/* Determine the initial link state. */
+	if (flags & DL_FLAG_STATELESS)
+		link->status = DL_STATE_NONE;
+	else
+		device_link_init_status(link, consumer, supplier);
+
+	/*
+	 * Some callers expect the link creation during consumer driver probe to
+	 * resume the supplier even without DL_FLAG_RPM_ACTIVE.
+	 */
+	if (link->status == DL_STATE_CONSUMER_PROBE &&
+	    flags & DL_FLAG_PM_RUNTIME)
+		pm_runtime_resume(supplier);
+
+	list_add_tail_rcu(&link->s_node, &supplier->links.consumers);
+	list_add_tail_rcu(&link->c_node, &consumer->links.suppliers);
+
+	if (flags & DL_FLAG_SYNC_STATE_ONLY) {
+		dev_dbg(consumer,
+			"Linked as a sync state only consumer to %s\n",
+			dev_name(supplier));
+		goto out;
+	}
+
+reorder:
+	/*
+	 * Move the consumer and all of the devices depending on it to the end
+	 * of dpm_list and the devices_kset list.
+	 *
+	 * It is necessary to hold dpm_list locked throughout all that or else
+	 * we may end up suspending with a wrong ordering of it.
+	 */
+	device_reorder_to_tail(consumer, NULL);
+
+	dev_dbg(consumer, "Linked as a consumer to %s\n", dev_name(supplier));
+
+out:
+	device_pm_unlock();
+	device_links_write_unlock();
+
+	if ((flags & DL_FLAG_PM_RUNTIME && flags & DL_FLAG_RPM_ACTIVE) && !link)
+		pm_runtime_put(supplier);
+
+	return link;
+}
+EXPORT_SYMBOL_GPL(device_link_add);
+
+/**
+ * device_link_wait_for_supplier - Add device to wait_for_suppliers list
+ * @consumer: Consumer device
+ *
+ * Marks the @consumer device as waiting for suppliers to become available by
+ * adding it to the wait_for_suppliers list. The consumer device will never be
+ * probed until it's removed from the wait_for_suppliers list.
+ *
+ * The caller is responsible for adding the links to the supplier devices once
+ * they are available and removing the @consumer device from the
+ * wait_for_suppliers list once links to all the suppliers have been created.
+ *
+ * This function is NOT meant to be called from the probe function of the
+ * consumer but rather from code that creates/adds the consumer device.
+ */
+static void device_link_wait_for_supplier(struct device *consumer,
+					  bool need_for_probe)
+{
+	mutex_lock(&wfs_lock);
+	list_add_tail(&consumer->links.needs_suppliers, &wait_for_suppliers);
+	consumer->links.need_for_probe = need_for_probe;
+	mutex_unlock(&wfs_lock);
+}
+
+static void device_link_wait_for_mandatory_supplier(struct device *consumer)
+{
+	device_link_wait_for_supplier(consumer, true);
+}
+
+static void device_link_wait_for_optional_supplier(struct device *consumer)
+{
+	device_link_wait_for_supplier(consumer, false);
+}
+
+/**
+ * device_link_add_missing_supplier_links - Add links from consumer devices to
+ *					    supplier devices, leaving any
+ *					    consumer with inactive suppliers on
+ *					    the wait_for_suppliers list
+ *
+ * Loops through all consumers waiting on suppliers and tries to add all their
+ * supplier links. If that succeeds, the consumer device is removed from
+ * wait_for_suppliers list. Otherwise, they are left in the wait_for_suppliers
+ * list.  Devices left on the wait_for_suppliers list will not be probed.
+ *
+ * The fwnode add_links callback is expected to return 0 if it has found and
+ * added all the supplier links for the consumer device. It should return an
+ * error if it isn't able to do so.
+ *
+ * The caller of device_link_wait_for_supplier() is expected to call this once
+ * it's aware of potential suppliers becoming available.
+ */
+static void device_link_add_missing_supplier_links(void)
+{
+	struct device *dev, *tmp;
+
+	mutex_lock(&wfs_lock);
+	list_for_each_entry_safe(dev, tmp, &wait_for_suppliers,
+				 links.needs_suppliers) {
+		int ret = fwnode_call_int_op(dev->fwnode, add_links, dev);
+		if (!ret)
+			list_del_init(&dev->links.needs_suppliers);
+		else if (ret != -ENODEV || fw_devlink_is_permissive())
+			dev->links.need_for_probe = false;
+	}
+	mutex_unlock(&wfs_lock);
+}
+
+#ifdef CONFIG_SRCU
+static void __device_link_del(struct kref *kref)
+{
+	struct device_link *link = container_of(kref, struct device_link, kref);
+
+	dev_dbg(link->consumer, "Dropping the link to %s\n",
+		dev_name(link->supplier));
+
+	pm_runtime_drop_link(link);
+
+	list_del_rcu(&link->s_node);
+	list_del_rcu(&link->c_node);
+	device_unregister(&link->link_dev);
+}
+#else /* !CONFIG_SRCU */
+static void __device_link_del(struct kref *kref)
+{
+	struct device_link *link = container_of(kref, struct device_link, kref);
+
+	dev_info(link->consumer, "Dropping the link to %s\n",
+		 dev_name(link->supplier));
+
+	pm_runtime_drop_link(link);
+
+	list_del(&link->s_node);
+	list_del(&link->c_node);
+	device_unregister(&link->link_dev);
+}
+#endif /* !CONFIG_SRCU */
+
+static void device_link_put_kref(struct device_link *link)
+{
+	if (link->flags & DL_FLAG_STATELESS)
+		kref_put(&link->kref, __device_link_del);
+	else
+		WARN(1, "Unable to drop a managed device link reference\n");
+}
+
+/**
+ * device_link_del - Delete a stateless link between two devices.
+ * @link: Device link to delete.
+ *
+ * The caller must ensure proper synchronization of this function with runtime
+ * PM.  If the link was added multiple times, it needs to be deleted as often.
+ * Care is required for hotplugged devices:  Their links are purged on removal
+ * and calling device_link_del() is then no longer allowed.
+ */
+void device_link_del(struct device_link *link)
+{
+	device_links_write_lock();
+	device_link_put_kref(link);
+	device_links_write_unlock();
+}
+EXPORT_SYMBOL_GPL(device_link_del);
+
+/**
+ * device_link_remove - Delete a stateless link between two devices.
+ * @consumer: Consumer end of the link.
+ * @supplier: Supplier end of the link.
+ *
+ * The caller must ensure proper synchronization of this function with runtime
+ * PM.
+ */
+void device_link_remove(void *consumer, struct device *supplier)
+{
+	struct device_link *link;
+
+	if (WARN_ON(consumer == supplier))
+		return;
+
+	device_links_write_lock();
+
+	list_for_each_entry(link, &supplier->links.consumers, s_node) {
+		if (link->consumer == consumer) {
+			device_link_put_kref(link);
+			break;
+		}
+	}
+
+	device_links_write_unlock();
+}
+EXPORT_SYMBOL_GPL(device_link_remove);
+
+static void device_links_missing_supplier(struct device *dev)
+{
+	struct device_link *link;
+
+	list_for_each_entry(link, &dev->links.suppliers, c_node) {
+		if (link->status != DL_STATE_CONSUMER_PROBE)
+			continue;
+
+		if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) {
+			WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
+		} else {
+			WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY));
+			WRITE_ONCE(link->status, DL_STATE_DORMANT);
+		}
+	}
+}
+
+/**
+ * device_links_check_suppliers - Check presence of supplier drivers.
+ * @dev: Consumer device.
+ *
+ * Check links from this device to any suppliers.  Walk the list of the device's
+ * links to suppliers and see if all of them are available.  If not, simply
+ * return -EPROBE_DEFER.
+ *
+ * We need to guarantee that the supplier will not go away after the check has
+ * been positive here.  It only can go away in __device_release_driver() and
+ * that function  checks the device's links to consumers.  This means we need to
+ * mark the link as "consumer probe in progress" to make the supplier removal
+ * wait for us to complete (or bad things may happen).
+ *
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
+ */
+int device_links_check_suppliers(struct device *dev)
+{
+	struct device_link *link;
+	int ret = 0;
+
+	/*
+	 * Device waiting for supplier to become available is not allowed to
+	 * probe.
+	 */
+	mutex_lock(&wfs_lock);
+	if (!list_empty(&dev->links.needs_suppliers) &&
+	    dev->links.need_for_probe) {
+		mutex_unlock(&wfs_lock);
+		return -EPROBE_DEFER;
+	}
+	mutex_unlock(&wfs_lock);
+
+	device_links_write_lock();
+
+	list_for_each_entry(link, &dev->links.suppliers, c_node) {
+		if (!(link->flags & DL_FLAG_MANAGED))
+			continue;
+
+		if (link->status != DL_STATE_AVAILABLE &&
+		    !(link->flags & DL_FLAG_SYNC_STATE_ONLY)) {
+			device_links_missing_supplier(dev);
+			ret = -EPROBE_DEFER;
+			break;
+		}
+		WRITE_ONCE(link->status, DL_STATE_CONSUMER_PROBE);
+	}
+	dev->links.status = DL_DEV_PROBING;
+
+	device_links_write_unlock();
+	return ret;
+}
+
+/**
+ * __device_links_queue_sync_state - Queue a device for sync_state() callback
+ * @dev: Device to call sync_state() on
+ * @list: List head to queue the @dev on
+ *
+ * Queues a device for a sync_state() callback when the device links write lock
+ * isn't held. This allows the sync_state() execution flow to use device links
+ * APIs.  The caller must ensure this function is called with
+ * device_links_write_lock() held.
+ *
+ * This function does a get_device() to make sure the device is not freed while
+ * on this list.
+ *
+ * So the caller must also ensure that device_links_flush_sync_list() is called
+ * as soon as the caller releases device_links_write_lock().  This is necessary
+ * to make sure the sync_state() is called in a timely fashion and the
+ * put_device() is called on this device.
+ */
+static void __device_links_queue_sync_state(struct device *dev,
+					    struct list_head *list)
+{
+	struct device_link *link;
+
+	if (!dev_has_sync_state(dev))
+		return;
+	if (dev->state_synced)
+		return;
+
+	list_for_each_entry(link, &dev->links.consumers, s_node) {
+		if (!(link->flags & DL_FLAG_MANAGED))
+			continue;
+		if (link->status != DL_STATE_ACTIVE)
+			return;
+	}
+
+	/*
+	 * Set the flag here to avoid adding the same device to a list more
+	 * than once. This can happen if new consumers get added to the device
+	 * and probed before the list is flushed.
+	 */
+	dev->state_synced = true;
+
+	if (WARN_ON(!list_empty(&dev->links.defer_hook)))
+		return;
+
+	get_device(dev);
+	list_add_tail(&dev->links.defer_hook, list);
+}
+
+/**
+ * device_links_flush_sync_list - Call sync_state() on a list of devices
+ * @list: List of devices to call sync_state() on
+ * @dont_lock_dev: Device for which lock is already held by the caller
+ *
+ * Calls sync_state() on all the devices that have been queued for it. This
+ * function is used in conjunction with __device_links_queue_sync_state(). The
+ * @dont_lock_dev parameter is useful when this function is called from a
+ * context where a device lock is already held.
+ */
+static void device_links_flush_sync_list(struct list_head *list,
+					 struct device *dont_lock_dev)
+{
+	struct device *dev, *tmp;
+
+	list_for_each_entry_safe(dev, tmp, list, links.defer_hook) {
+		list_del_init(&dev->links.defer_hook);
+
+		if (dev != dont_lock_dev)
+			device_lock(dev);
+
+		if (dev->bus->sync_state)
+			dev->bus->sync_state(dev);
+		else if (dev->driver && dev->driver->sync_state)
+			dev->driver->sync_state(dev);
+
+		if (dev != dont_lock_dev)
+			device_unlock(dev);
+
+		put_device(dev);
+	}
+}
+
+void device_links_supplier_sync_state_pause(void)
+{
+	device_links_write_lock();
+	defer_sync_state_count++;
+	device_links_write_unlock();
+}
+
+void device_links_supplier_sync_state_resume(void)
+{
+	struct device *dev, *tmp;
+	LIST_HEAD(sync_list);
+
+	device_links_write_lock();
+	if (!defer_sync_state_count) {
+		WARN(true, "Unmatched sync_state pause/resume!");
+		goto out;
+	}
+	defer_sync_state_count--;
+	if (defer_sync_state_count)
+		goto out;
+
+	list_for_each_entry_safe(dev, tmp, &deferred_sync, links.defer_hook) {
+		/*
+		 * Delete from deferred_sync list before queuing it to
+		 * sync_list because defer_hook is used for both lists.
+		 */
+		list_del_init(&dev->links.defer_hook);
+		__device_links_queue_sync_state(dev, &sync_list);
+	}
+out:
+	device_links_write_unlock();
+
+	device_links_flush_sync_list(&sync_list, NULL);
+}
+
+static int sync_state_resume_initcall(void)
+{
+	device_links_supplier_sync_state_resume();
+	return 0;
+}
+late_initcall(sync_state_resume_initcall);
+
+static void __device_links_supplier_defer_sync(struct device *sup)
+{
+	if (list_empty(&sup->links.defer_hook) && dev_has_sync_state(sup))
+		list_add_tail(&sup->links.defer_hook, &deferred_sync);
+}
+
+static void device_link_drop_managed(struct device_link *link)
+{
+	link->flags &= ~DL_FLAG_MANAGED;
+	WRITE_ONCE(link->status, DL_STATE_NONE);
+	kref_put(&link->kref, __device_link_del);
+}
+
+static ssize_t waiting_for_supplier_show(struct device *dev,
+					 struct device_attribute *attr,
+					 char *buf)
+{
+	bool val;
+
+	device_lock(dev);
+	mutex_lock(&wfs_lock);
+	val = !list_empty(&dev->links.needs_suppliers)
+	      && dev->links.need_for_probe;
+	mutex_unlock(&wfs_lock);
+	device_unlock(dev);
+	return sysfs_emit(buf, "%u\n", val);
+}
+static DEVICE_ATTR_RO(waiting_for_supplier);
+
+/**
+ * device_links_driver_bound - Update device links after probing its driver.
+ * @dev: Device to update the links for.
+ *
+ * The probe has been successful, so update links from this device to any
+ * consumers by changing their status to "available".
+ *
+ * Also change the status of @dev's links to suppliers to "active".
+ *
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
+ */
+void device_links_driver_bound(struct device *dev)
+{
+	struct device_link *link, *ln;
+	LIST_HEAD(sync_list);
+
+	/*
+	 * If a device probes successfully, it's expected to have created all
+	 * the device links it needs to or make new device links as it needs
+	 * them. So, it no longer needs to wait on any suppliers.
+	 */
+	mutex_lock(&wfs_lock);
+	list_del_init(&dev->links.needs_suppliers);
+	mutex_unlock(&wfs_lock);
+	device_remove_file(dev, &dev_attr_waiting_for_supplier);
+
+	device_links_write_lock();
+
+	list_for_each_entry(link, &dev->links.consumers, s_node) {
+		if (!(link->flags & DL_FLAG_MANAGED))
+			continue;
+
+		/*
+		 * Links created during consumer probe may be in the "consumer
+		 * probe" state to start with if the supplier is still probing
+		 * when they are created and they may become "active" if the
+		 * consumer probe returns first.  Skip them here.
+		 */
+		if (link->status == DL_STATE_CONSUMER_PROBE ||
+		    link->status == DL_STATE_ACTIVE)
+			continue;
+
+		WARN_ON(link->status != DL_STATE_DORMANT);
+		WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
+
+		if (link->flags & DL_FLAG_AUTOPROBE_CONSUMER)
+			driver_deferred_probe_add(link->consumer);
+	}
+
+	if (defer_sync_state_count)
+		__device_links_supplier_defer_sync(dev);
+	else
+		__device_links_queue_sync_state(dev, &sync_list);
+
+	list_for_each_entry_safe(link, ln, &dev->links.suppliers, c_node) {
+		struct device *supplier;
+
+		if (!(link->flags & DL_FLAG_MANAGED))
+			continue;
+
+		supplier = link->supplier;
+		if (link->flags & DL_FLAG_SYNC_STATE_ONLY) {
+			/*
+			 * When DL_FLAG_SYNC_STATE_ONLY is set, it means no
+			 * other DL_MANAGED_LINK_FLAGS have been set. So, it's
+			 * save to drop the managed link completely.
+			 */
+			device_link_drop_managed(link);
+		} else {
+			WARN_ON(link->status != DL_STATE_CONSUMER_PROBE);
+			WRITE_ONCE(link->status, DL_STATE_ACTIVE);
+		}
+
+		/*
+		 * This needs to be done even for the deleted
+		 * DL_FLAG_SYNC_STATE_ONLY device link in case it was the last
+		 * device link that was preventing the supplier from getting a
+		 * sync_state() call.
+		 */
+		if (defer_sync_state_count)
+			__device_links_supplier_defer_sync(supplier);
+		else
+			__device_links_queue_sync_state(supplier, &sync_list);
+	}
+
+	dev->links.status = DL_DEV_DRIVER_BOUND;
+
+	device_links_write_unlock();
+
+	device_links_flush_sync_list(&sync_list, dev);
+}
+
+/**
+ * __device_links_no_driver - Update links of a device without a driver.
+ * @dev: Device without a drvier.
+ *
+ * Delete all non-persistent links from this device to any suppliers.
+ *
+ * Persistent links stay around, but their status is changed to "available",
+ * unless they already are in the "supplier unbind in progress" state in which
+ * case they need not be updated.
+ *
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
+ */
+static void __device_links_no_driver(struct device *dev)
+{
+	struct device_link *link, *ln;
+
+	list_for_each_entry_safe_reverse(link, ln, &dev->links.suppliers, c_node) {
+		if (!(link->flags & DL_FLAG_MANAGED))
+			continue;
+
+		if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER) {
+			device_link_drop_managed(link);
+			continue;
+		}
+
+		if (link->status != DL_STATE_CONSUMER_PROBE &&
+		    link->status != DL_STATE_ACTIVE)
+			continue;
+
+		if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) {
+			WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
+		} else {
+			WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY));
+			WRITE_ONCE(link->status, DL_STATE_DORMANT);
+		}
+	}
+
+	dev->links.status = DL_DEV_NO_DRIVER;
+}
+
+/**
+ * device_links_no_driver - Update links after failing driver probe.
+ * @dev: Device whose driver has just failed to probe.
+ *
+ * Clean up leftover links to consumers for @dev and invoke
+ * %__device_links_no_driver() to update links to suppliers for it as
+ * appropriate.
+ *
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
+ */
+void device_links_no_driver(struct device *dev)
+{
+	struct device_link *link;
+
+	device_links_write_lock();
+
+	list_for_each_entry(link, &dev->links.consumers, s_node) {
+		if (!(link->flags & DL_FLAG_MANAGED))
+			continue;
+
+		/*
+		 * The probe has failed, so if the status of the link is
+		 * "consumer probe" or "active", it must have been added by
+		 * a probing consumer while this device was still probing.
+		 * Change its state to "dormant", as it represents a valid
+		 * relationship, but it is not functionally meaningful.
+		 */
+		if (link->status == DL_STATE_CONSUMER_PROBE ||
+		    link->status == DL_STATE_ACTIVE)
+			WRITE_ONCE(link->status, DL_STATE_DORMANT);
+	}
+
+	__device_links_no_driver(dev);
+
+	device_links_write_unlock();
+}
+
+/**
+ * device_links_driver_cleanup - Update links after driver removal.
+ * @dev: Device whose driver has just gone away.
+ *
+ * Update links to consumers for @dev by changing their status to "dormant" and
+ * invoke %__device_links_no_driver() to update links to suppliers for it as
+ * appropriate.
+ *
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
+ */
+void device_links_driver_cleanup(struct device *dev)
+{
+	struct device_link *link, *ln;
+
+	device_links_write_lock();
+
+	list_for_each_entry_safe(link, ln, &dev->links.consumers, s_node) {
+		if (!(link->flags & DL_FLAG_MANAGED))
+			continue;
+
+		WARN_ON(link->flags & DL_FLAG_AUTOREMOVE_CONSUMER);
+		WARN_ON(link->status != DL_STATE_SUPPLIER_UNBIND);
+
+		/*
+		 * autoremove the links between this @dev and its consumer
+		 * devices that are not active, i.e. where the link state
+		 * has moved to DL_STATE_SUPPLIER_UNBIND.
+		 */
+		if (link->status == DL_STATE_SUPPLIER_UNBIND &&
+		    link->flags & DL_FLAG_AUTOREMOVE_SUPPLIER)
+			device_link_drop_managed(link);
+
+		WRITE_ONCE(link->status, DL_STATE_DORMANT);
+	}
+
+	list_del_init(&dev->links.defer_hook);
+	__device_links_no_driver(dev);
+
+	device_links_write_unlock();
+}
+
+/**
+ * device_links_busy - Check if there are any busy links to consumers.
+ * @dev: Device to check.
+ *
+ * Check each consumer of the device and return 'true' if its link's status
+ * is one of "consumer probe" or "active" (meaning that the given consumer is
+ * probing right now or its driver is present).  Otherwise, change the link
+ * state to "supplier unbind" to prevent the consumer from being probed
+ * successfully going forward.
+ *
+ * Return 'false' if there are no probing or active consumers.
+ *
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
+ */
+bool device_links_busy(struct device *dev)
+{
+	struct device_link *link;
+	bool ret = false;
+
+	device_links_write_lock();
+
+	list_for_each_entry(link, &dev->links.consumers, s_node) {
+		if (!(link->flags & DL_FLAG_MANAGED))
+			continue;
+
+		if (link->status == DL_STATE_CONSUMER_PROBE
+		    || link->status == DL_STATE_ACTIVE) {
+			ret = true;
+			break;
+		}
+		WRITE_ONCE(link->status, DL_STATE_SUPPLIER_UNBIND);
+	}
+
+	dev->links.status = DL_DEV_UNBINDING;
+
+	device_links_write_unlock();
+	return ret;
+}
+
+/**
+ * device_links_unbind_consumers - Force unbind consumers of the given device.
+ * @dev: Device to unbind the consumers of.
+ *
+ * Walk the list of links to consumers for @dev and if any of them is in the
+ * "consumer probe" state, wait for all device probes in progress to complete
+ * and start over.
+ *
+ * If that's not the case, change the status of the link to "supplier unbind"
+ * and check if the link was in the "active" state.  If so, force the consumer
+ * driver to unbind and start over (the consumer will not re-probe as we have
+ * changed the state of the link already).
+ *
+ * Links without the DL_FLAG_MANAGED flag set are ignored.
+ */
+void device_links_unbind_consumers(struct device *dev)
+{
+	struct device_link *link;
+
+ start:
+	device_links_write_lock();
+
+	list_for_each_entry(link, &dev->links.consumers, s_node) {
+		enum device_link_state status;
+
+		if (!(link->flags & DL_FLAG_MANAGED) ||
+		    link->flags & DL_FLAG_SYNC_STATE_ONLY)
+			continue;
+
+		status = link->status;
+		if (status == DL_STATE_CONSUMER_PROBE) {
+			device_links_write_unlock();
+
+			wait_for_device_probe();
+			goto start;
+		}
+		WRITE_ONCE(link->status, DL_STATE_SUPPLIER_UNBIND);
+		if (status == DL_STATE_ACTIVE) {
+			struct device *consumer = link->consumer;
+
+			get_device(consumer);
+
+			device_links_write_unlock();
+
+			device_release_driver_internal(consumer, NULL,
+						       consumer->parent);
+			put_device(consumer);
+			goto start;
+		}
+	}
+
+	device_links_write_unlock();
+}
+
+/**
+ * device_links_purge - Delete existing links to other devices.
+ * @dev: Target device.
+ */
+static void device_links_purge(struct device *dev)
+{
+	struct device_link *link, *ln;
+
+	if (dev->class == &devlink_class)
+		return;
+
+	mutex_lock(&wfs_lock);
+	list_del_init(&dev->links.needs_suppliers);
+	mutex_unlock(&wfs_lock);
+
+	/*
+	 * Delete all of the remaining links from this device to any other
+	 * devices (either consumers or suppliers).
+	 */
+	device_links_write_lock();
+
+	list_for_each_entry_safe_reverse(link, ln, &dev->links.suppliers, c_node) {
+		WARN_ON(link->status == DL_STATE_ACTIVE);
+		__device_link_del(&link->kref);
+	}
+
+	list_for_each_entry_safe_reverse(link, ln, &dev->links.consumers, s_node) {
+		WARN_ON(link->status != DL_STATE_DORMANT &&
+			link->status != DL_STATE_NONE);
+		__device_link_del(&link->kref);
+	}
+
+	device_links_write_unlock();
+}
+
+static u32 fw_devlink_flags = DL_FLAG_SYNC_STATE_ONLY;
+static int __init fw_devlink_setup(char *arg)
+{
+	if (!arg)
+		return -EINVAL;
+
+	if (strcmp(arg, "off") == 0) {
+		fw_devlink_flags = 0;
+	} else if (strcmp(arg, "permissive") == 0) {
+		fw_devlink_flags = DL_FLAG_SYNC_STATE_ONLY;
+	} else if (strcmp(arg, "on") == 0) {
+		fw_devlink_flags = DL_FLAG_AUTOPROBE_CONSUMER;
+	} else if (strcmp(arg, "rpm") == 0) {
+		fw_devlink_flags = DL_FLAG_AUTOPROBE_CONSUMER |
+				   DL_FLAG_PM_RUNTIME;
+	}
+	return 0;
+}
+early_param("fw_devlink", fw_devlink_setup);
+
+u32 fw_devlink_get_flags(void)
+{
+	return fw_devlink_flags;
+}
+
+static bool fw_devlink_is_permissive(void)
+{
+	return fw_devlink_flags == DL_FLAG_SYNC_STATE_ONLY;
+}
+
+static void fw_devlink_link_device(struct device *dev)
+{
+	int fw_ret;
+
+	if (!fw_devlink_flags)
+		return;
+
+	mutex_lock(&defer_fw_devlink_lock);
+	if (!defer_fw_devlink_count)
+		device_link_add_missing_supplier_links();
+
+	/*
+	 * The device's fwnode not having add_links() doesn't affect if other
+	 * consumers can find this device as a supplier.  So, this check is
+	 * intentionally placed after device_link_add_missing_supplier_links().
+	 */
+	if (!fwnode_has_op(dev->fwnode, add_links))
+		goto out;
+
+	/*
+	 * If fw_devlink is being deferred, assume all devices have mandatory
+	 * suppliers they need to link to later. Then, when the fw_devlink is
+	 * resumed, all these devices will get a chance to try and link to any
+	 * suppliers they have.
+	 */
+	if (!defer_fw_devlink_count) {
+		fw_ret = fwnode_call_int_op(dev->fwnode, add_links, dev);
+		if (fw_ret == -ENODEV && fw_devlink_is_permissive())
+			fw_ret = -EAGAIN;
+	} else {
+		fw_ret = -ENODEV;
+		/*
+		 * defer_hook is not used to add device to deferred_sync list
+		 * until device is bound. Since deferred fw devlink also blocks
+		 * probing, same list hook can be used for deferred_fw_devlink.
+		 */
+		list_add_tail(&dev->links.defer_hook, &deferred_fw_devlink);
+	}
+
+	if (fw_ret == -ENODEV)
+		device_link_wait_for_mandatory_supplier(dev);
+	else if (fw_ret)
+		device_link_wait_for_optional_supplier(dev);
+
+out:
+	mutex_unlock(&defer_fw_devlink_lock);
+}
+
+/**
+ * fw_devlink_pause - Pause parsing of fwnode to create device links
+ *
+ * Calling this function defers any fwnode parsing to create device links until
+ * fw_devlink_resume() is called. Both these functions are ref counted and the
+ * caller needs to match the calls.
+ *
+ * While fw_devlink is paused:
+ * - Any device that is added won't have its fwnode parsed to create device
+ *   links.
+ * - The probe of the device will also be deferred during this period.
+ * - Any devices that were already added, but waiting for suppliers won't be
+ *   able to link to newly added devices.
+ *
+ * Once fw_devlink_resume():
+ * - All the fwnodes that was not parsed will be parsed.
+ * - All the devices that were deferred probing will be reattempted if they
+ *   aren't waiting for any more suppliers.
+ *
+ * This pair of functions, is mainly meant to optimize the parsing of fwnodes
+ * when a lot of devices that need to link to each other are added in a short
+ * interval of time. For example, adding all the top level devices in a system.
+ *
+ * For example, if N devices are added and:
+ * - All the consumers are added before their suppliers
+ * - All the suppliers of the N devices are part of the N devices
+ *
+ * Then:
+ *
+ * - With the use of fw_devlink_pause() and fw_devlink_resume(), each device
+ *   will only need one parsing of its fwnode because it is guaranteed to find
+ *   all the supplier devices already registered and ready to link to. It won't
+ *   have to do another pass later to find one or more suppliers it couldn't
+ *   find in the first parse of the fwnode. So, we'll only need O(N) fwnode
+ *   parses.
+ *
+ * - Without the use of fw_devlink_pause() and fw_devlink_resume(), we would
+ *   end up doing O(N^2) parses of fwnodes because every device that's added is
+ *   guaranteed to trigger a parse of the fwnode of every device added before
+ *   it. This O(N^2) parse is made worse by the fact that when a fwnode of a
+ *   device is parsed, all it descendant devices might need to have their
+ *   fwnodes parsed too (even if the devices themselves aren't added).
+ */
+void fw_devlink_pause(void)
+{
+	mutex_lock(&defer_fw_devlink_lock);
+	defer_fw_devlink_count++;
+	mutex_unlock(&defer_fw_devlink_lock);
+}
+
+/** fw_devlink_resume - Resume parsing of fwnode to create device links
+ *
+ * This function is used in conjunction with fw_devlink_pause() and is ref
+ * counted. See documentation for fw_devlink_pause() for more details.
+ */
+void fw_devlink_resume(void)
+{
+	struct device *dev, *tmp;
+	LIST_HEAD(probe_list);
+
+	mutex_lock(&defer_fw_devlink_lock);
+	if (!defer_fw_devlink_count) {
+		WARN(true, "Unmatched fw_devlink pause/resume!");
+		goto out;
+	}
+
+	defer_fw_devlink_count--;
+	if (defer_fw_devlink_count)
+		goto out;
+
+	device_link_add_missing_supplier_links();
+	list_splice_tail_init(&deferred_fw_devlink, &probe_list);
+out:
+	mutex_unlock(&defer_fw_devlink_lock);
+
+	/*
+	 * bus_probe_device() can cause new devices to get added and they'll
+	 * try to grab defer_fw_devlink_lock. So, this needs to be done outside
+	 * the defer_fw_devlink_lock.
+	 */
+	list_for_each_entry_safe(dev, tmp, &probe_list, links.defer_hook) {
+		list_del_init(&dev->links.defer_hook);
+		bus_probe_device(dev);
+	}
+}
+/* Device links support end. */
+
+int (*platform_notify)(struct device *dev) = NULL;
+int (*platform_notify_remove)(struct device *dev) = NULL;
+static struct kobject *dev_kobj;
+struct kobject *sysfs_dev_char_kobj;
+struct kobject *sysfs_dev_block_kobj;
+
+static DEFINE_MUTEX(device_hotplug_lock);
+
+void lock_device_hotplug(void)
+{
+	mutex_lock(&device_hotplug_lock);
+}
+
+void unlock_device_hotplug(void)
+{
+	mutex_unlock(&device_hotplug_lock);
+}
+
+int lock_device_hotplug_sysfs(void)
+{
+	if (mutex_trylock(&device_hotplug_lock))
+		return 0;
+
+	/* Avoid busy looping (5 ms of sleep should do). */
+	msleep(5);
+	return restart_syscall();
+}
+
+#ifdef CONFIG_BLOCK
+static inline int device_is_not_partition(struct device *dev)
+{
+	return !(dev->type == &part_type);
+}
+#else
+static inline int device_is_not_partition(struct device *dev)
+{
+	return 1;
+}
+#endif
+
+static int
+device_platform_notify(struct device *dev, enum kobject_action action)
+{
+	int ret;
+
+	ret = acpi_platform_notify(dev, action);
+	if (ret)
+		return ret;
+
+	ret = software_node_notify(dev, action);
+	if (ret)
+		return ret;
+
+	if (platform_notify && action == KOBJ_ADD)
+		platform_notify(dev);
+	else if (platform_notify_remove && action == KOBJ_REMOVE)
+		platform_notify_remove(dev);
+	return 0;
+}
+
+/**
+ * dev_driver_string - Return a device's driver name, if at all possible
+ * @dev: struct device to get the name of
+ *
+ * Will return the device's driver's name if it is bound to a device.  If
+ * the device is not bound to a driver, it will return the name of the bus
+ * it is attached to.  If it is not attached to a bus either, an empty
+ * string will be returned.
+ */
+const char *dev_driver_string(const struct device *dev)
+{
+	struct device_driver *drv;
+
+	/* dev->driver can change to NULL underneath us because of unbinding,
+	 * so be careful about accessing it.  dev->bus and dev->class should
+	 * never change once they are set, so they don't need special care.
+	 */
+	drv = READ_ONCE(dev->driver);
+	return drv ? drv->name : dev_bus_name(dev);
+}
+EXPORT_SYMBOL(dev_driver_string);
+
+#define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
+
+static ssize_t dev_attr_show(struct kobject *kobj, struct attribute *attr,
+			     char *buf)
+{
+	struct device_attribute *dev_attr = to_dev_attr(attr);
+	struct device *dev = kobj_to_dev(kobj);
+	ssize_t ret = -EIO;
+
+	if (dev_attr->show)
+		ret = dev_attr->show(dev, dev_attr, buf);
+	if (ret >= (ssize_t)PAGE_SIZE) {
+		printk("dev_attr_show: %pS returned bad count\n",
+				dev_attr->show);
+	}
+	return ret;
+}
+
+static ssize_t dev_attr_store(struct kobject *kobj, struct attribute *attr,
+			      const char *buf, size_t count)
+{
+	struct device_attribute *dev_attr = to_dev_attr(attr);
+	struct device *dev = kobj_to_dev(kobj);
+	ssize_t ret = -EIO;
+
+	if (dev_attr->store)
+		ret = dev_attr->store(dev, dev_attr, buf, count);
+	return ret;
+}
+
+static const struct sysfs_ops dev_sysfs_ops = {
+	.show	= dev_attr_show,
+	.store	= dev_attr_store,
+};
+
+#define to_ext_attr(x) container_of(x, struct dev_ext_attribute, attr)
+
+ssize_t device_store_ulong(struct device *dev,
+			   struct device_attribute *attr,
+			   const char *buf, size_t size)
+{
+	struct dev_ext_attribute *ea = to_ext_attr(attr);
+	int ret;
+	unsigned long new;
+
+	ret = kstrtoul(buf, 0, &new);
+	if (ret)
+		return ret;
+	*(unsigned long *)(ea->var) = new;
+	/* Always return full write size even if we didn't consume all */
+	return size;
+}
+EXPORT_SYMBOL_GPL(device_store_ulong);
+
+ssize_t device_show_ulong(struct device *dev,
+			  struct device_attribute *attr,
+			  char *buf)
+{
+	struct dev_ext_attribute *ea = to_ext_attr(attr);
+	return sysfs_emit(buf, "%lx\n", *(unsigned long *)(ea->var));
+}
+EXPORT_SYMBOL_GPL(device_show_ulong);
+
+ssize_t device_store_int(struct device *dev,
+			 struct device_attribute *attr,
+			 const char *buf, size_t size)
+{
+	struct dev_ext_attribute *ea = to_ext_attr(attr);
+	int ret;
+	long new;
+
+	ret = kstrtol(buf, 0, &new);
+	if (ret)
+		return ret;
+
+	if (new > INT_MAX || new < INT_MIN)
+		return -EINVAL;
+	*(int *)(ea->var) = new;
+	/* Always return full write size even if we didn't consume all */
+	return size;
+}
+EXPORT_SYMBOL_GPL(device_store_int);
+
+ssize_t device_show_int(struct device *dev,
+			struct device_attribute *attr,
+			char *buf)
+{
+	struct dev_ext_attribute *ea = to_ext_attr(attr);
+
+	return sysfs_emit(buf, "%d\n", *(int *)(ea->var));
+}
+EXPORT_SYMBOL_GPL(device_show_int);
+
+ssize_t device_store_bool(struct device *dev, struct device_attribute *attr,
+			  const char *buf, size_t size)
+{
+	struct dev_ext_attribute *ea = to_ext_attr(attr);
+
+	if (strtobool(buf, ea->var) < 0)
+		return -EINVAL;
+
+	return size;
+}
+EXPORT_SYMBOL_GPL(device_store_bool);
+
+ssize_t device_show_bool(struct device *dev, struct device_attribute *attr,
+			 char *buf)
+{
+	struct dev_ext_attribute *ea = to_ext_attr(attr);
+
+	return sysfs_emit(buf, "%d\n", *(bool *)(ea->var));
+}
+EXPORT_SYMBOL_GPL(device_show_bool);
+
+/**
+ * device_release - free device structure.
+ * @kobj: device's kobject.
+ *
+ * This is called once the reference count for the object
+ * reaches 0. We forward the call to the device's release
+ * method, which should handle actually freeing the structure.
+ */
+static void device_release(struct kobject *kobj)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct device_private *p = dev->p;
+
+	/*
+	 * Some platform devices are driven without driver attached
+	 * and managed resources may have been acquired.  Make sure
+	 * all resources are released.
+	 *
+	 * Drivers still can add resources into device after device
+	 * is deleted but alive, so release devres here to avoid
+	 * possible memory leak.
+	 */
+	devres_release_all(dev);
+
+	kfree(dev->dma_range_map);
+
+	if (dev->release)
+		dev->release(dev);
+	else if (dev->type && dev->type->release)
+		dev->type->release(dev);
+	else if (dev->class && dev->class->dev_release)
+		dev->class->dev_release(dev);
+	else
+		WARN(1, KERN_ERR "Device '%s' does not have a release() function, it is broken and must be fixed. See Documentation/core-api/kobject.rst.\n",
+			dev_name(dev));
+	kfree(p);
+}
+
+static const void *device_namespace(struct kobject *kobj)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	const void *ns = NULL;
+
+	if (dev->class && dev->class->ns_type)
+		ns = dev->class->namespace(dev);
+
+	return ns;
+}
+
+static void device_get_ownership(struct kobject *kobj, kuid_t *uid, kgid_t *gid)
+{
+	struct device *dev = kobj_to_dev(kobj);
+
+	if (dev->class && dev->class->get_ownership)
+		dev->class->get_ownership(dev, uid, gid);
+}
+
+static struct kobj_type device_ktype = {
+	.release	= device_release,
+	.sysfs_ops	= &dev_sysfs_ops,
+	.namespace	= device_namespace,
+	.get_ownership	= device_get_ownership,
+};
+
+
+static int dev_uevent_filter(struct kset *kset, struct kobject *kobj)
+{
+	struct kobj_type *ktype = get_ktype(kobj);
+
+	if (ktype == &device_ktype) {
+		struct device *dev = kobj_to_dev(kobj);
+		if (dev->bus)
+			return 1;
+		if (dev->class)
+			return 1;
+	}
+	return 0;
+}
+
+static const char *dev_uevent_name(struct kset *kset, struct kobject *kobj)
+{
+	struct device *dev = kobj_to_dev(kobj);
+
+	if (dev->bus)
+		return dev->bus->name;
+	if (dev->class)
+		return dev->class->name;
+	return NULL;
+}
+
+static int dev_uevent(struct kset *kset, struct kobject *kobj,
+		      struct kobj_uevent_env *env)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	int retval = 0;
+
+	/* add device node properties if present */
+	if (MAJOR(dev->devt)) {
+		const char *tmp;
+		const char *name;
+		umode_t mode = 0;
+		kuid_t uid = GLOBAL_ROOT_UID;
+		kgid_t gid = GLOBAL_ROOT_GID;
+
+		add_uevent_var(env, "MAJOR=%u", MAJOR(dev->devt));
+		add_uevent_var(env, "MINOR=%u", MINOR(dev->devt));
+		name = device_get_devnode(dev, &mode, &uid, &gid, &tmp);
+		if (name) {
+			add_uevent_var(env, "DEVNAME=%s", name);
+			if (mode)
+				add_uevent_var(env, "DEVMODE=%#o", mode & 0777);
+			if (!uid_eq(uid, GLOBAL_ROOT_UID))
+				add_uevent_var(env, "DEVUID=%u", from_kuid(&init_user_ns, uid));
+			if (!gid_eq(gid, GLOBAL_ROOT_GID))
+				add_uevent_var(env, "DEVGID=%u", from_kgid(&init_user_ns, gid));
+			kfree(tmp);
+		}
+	}
+
+	if (dev->type && dev->type->name)
+		add_uevent_var(env, "DEVTYPE=%s", dev->type->name);
+
+	if (dev->driver)
+		add_uevent_var(env, "DRIVER=%s", dev->driver->name);
+
+	/* Add common DT information about the device */
+	of_device_uevent(dev, env);
+
+	/* have the bus specific function add its stuff */
+	if (dev->bus && dev->bus->uevent) {
+		retval = dev->bus->uevent(dev, env);
+		if (retval)
+			pr_debug("device: '%s': %s: bus uevent() returned %d\n",
+				 dev_name(dev), __func__, retval);
+	}
+
+	/* have the class specific function add its stuff */
+	if (dev->class && dev->class->dev_uevent) {
+		retval = dev->class->dev_uevent(dev, env);
+		if (retval)
+			pr_debug("device: '%s': %s: class uevent() "
+				 "returned %d\n", dev_name(dev),
+				 __func__, retval);
+	}
+
+	/* have the device type specific function add its stuff */
+	if (dev->type && dev->type->uevent) {
+		retval = dev->type->uevent(dev, env);
+		if (retval)
+			pr_debug("device: '%s': %s: dev_type uevent() "
+				 "returned %d\n", dev_name(dev),
+				 __func__, retval);
+	}
+
+	return retval;
+}
+
+static const struct kset_uevent_ops device_uevent_ops = {
+	.filter =	dev_uevent_filter,
+	.name =		dev_uevent_name,
+	.uevent =	dev_uevent,
+};
+
+static ssize_t uevent_show(struct device *dev, struct device_attribute *attr,
+			   char *buf)
+{
+	struct kobject *top_kobj;
+	struct kset *kset;
+	struct kobj_uevent_env *env = NULL;
+	int i;
+	int len = 0;
+	int retval;
+
+	/* search the kset, the device belongs to */
+	top_kobj = &dev->kobj;
+	while (!top_kobj->kset && top_kobj->parent)
+		top_kobj = top_kobj->parent;
+	if (!top_kobj->kset)
+		goto out;
+
+	kset = top_kobj->kset;
+	if (!kset->uevent_ops || !kset->uevent_ops->uevent)
+		goto out;
+
+	/* respect filter */
+	if (kset->uevent_ops && kset->uevent_ops->filter)
+		if (!kset->uevent_ops->filter(kset, &dev->kobj))
+			goto out;
+
+	env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
+	if (!env)
+		return -ENOMEM;
+
+	/* let the kset specific function add its keys */
+	retval = kset->uevent_ops->uevent(kset, &dev->kobj, env);
+	if (retval)
+		goto out;
+
+	/* copy keys to file */
+	for (i = 0; i < env->envp_idx; i++)
+		len += sysfs_emit_at(buf, len, "%s\n", env->envp[i]);
+out:
+	kfree(env);
+	return len;
+}
+
+static ssize_t uevent_store(struct device *dev, struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	int rc;
+
+	rc = kobject_synth_uevent(&dev->kobj, buf, count);
+
+	if (rc) {
+		dev_err(dev, "uevent: failed to send synthetic uevent\n");
+		return rc;
+	}
+
+	return count;
+}
+static DEVICE_ATTR_RW(uevent);
+
+static ssize_t online_show(struct device *dev, struct device_attribute *attr,
+			   char *buf)
+{
+	bool val;
+
+	device_lock(dev);
+	val = !dev->offline;
+	device_unlock(dev);
+	return sysfs_emit(buf, "%u\n", val);
+}
+
+static ssize_t online_store(struct device *dev, struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	bool val;
+	int ret;
+
+	ret = strtobool(buf, &val);
+	if (ret < 0)
+		return ret;
+
+	ret = lock_device_hotplug_sysfs();
+	if (ret)
+		return ret;
+
+	ret = val ? device_online(dev) : device_offline(dev);
+	unlock_device_hotplug();
+	return ret < 0 ? ret : count;
+}
+static DEVICE_ATTR_RW(online);
+
+static ssize_t removable_show(struct device *dev, struct device_attribute *attr,
+			      char *buf)
+{
+	const char *loc;
+
+	switch (dev->removable) {
+	case DEVICE_REMOVABLE:
+		loc = "removable";
+		break;
+	case DEVICE_FIXED:
+		loc = "fixed";
+		break;
+	default:
+		loc = "unknown";
+	}
+	return sysfs_emit(buf, "%s\n", loc);
+}
+static DEVICE_ATTR_RO(removable);
+
+int device_add_groups(struct device *dev, const struct attribute_group **groups)
+{
+	return sysfs_create_groups(&dev->kobj, groups);
+}
+EXPORT_SYMBOL_GPL(device_add_groups);
+
+void device_remove_groups(struct device *dev,
+			  const struct attribute_group **groups)
+{
+	sysfs_remove_groups(&dev->kobj, groups);
+}
+EXPORT_SYMBOL_GPL(device_remove_groups);
+
+union device_attr_group_devres {
+	const struct attribute_group *group;
+	const struct attribute_group **groups;
+};
+
+static int devm_attr_group_match(struct device *dev, void *res, void *data)
+{
+	return ((union device_attr_group_devres *)res)->group == data;
+}
+
+static void devm_attr_group_remove(struct device *dev, void *res)
+{
+	union device_attr_group_devres *devres = res;
+	const struct attribute_group *group = devres->group;
+
+	dev_dbg(dev, "%s: removing group %p\n", __func__, group);
+	sysfs_remove_group(&dev->kobj, group);
+}
+
+static void devm_attr_groups_remove(struct device *dev, void *res)
+{
+	union device_attr_group_devres *devres = res;
+	const struct attribute_group **groups = devres->groups;
+
+	dev_dbg(dev, "%s: removing groups %p\n", __func__, groups);
+	sysfs_remove_groups(&dev->kobj, groups);
+}
+
+/**
+ * devm_device_add_group - given a device, create a managed attribute group
+ * @dev:	The device to create the group for
+ * @grp:	The attribute group to create
+ *
+ * This function creates a group for the first time.  It will explicitly
+ * warn and error if any of the attribute files being created already exist.
+ *
+ * Returns 0 on success or error code on failure.
+ */
+int devm_device_add_group(struct device *dev, const struct attribute_group *grp)
+{
+	union device_attr_group_devres *devres;
+	int error;
+
+	devres = devres_alloc(devm_attr_group_remove,
+			      sizeof(*devres), GFP_KERNEL);
+	if (!devres)
+		return -ENOMEM;
+
+	error = sysfs_create_group(&dev->kobj, grp);
+	if (error) {
+		devres_free(devres);
+		return error;
+	}
+
+	devres->group = grp;
+	devres_add(dev, devres);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(devm_device_add_group);
+
+/**
+ * devm_device_remove_group: remove a managed group from a device
+ * @dev:	device to remove the group from
+ * @grp:	group to remove
+ *
+ * This function removes a group of attributes from a device. The attributes
+ * previously have to have been created for this group, otherwise it will fail.
+ */
+void devm_device_remove_group(struct device *dev,
+			      const struct attribute_group *grp)
+{
+	WARN_ON(devres_release(dev, devm_attr_group_remove,
+			       devm_attr_group_match,
+			       /* cast away const */ (void *)grp));
+}
+EXPORT_SYMBOL_GPL(devm_device_remove_group);
+
+/**
+ * devm_device_add_groups - create a bunch of managed attribute groups
+ * @dev:	The device to create the group for
+ * @groups:	The attribute groups to create, NULL terminated
+ *
+ * This function creates a bunch of managed attribute groups.  If an error
+ * occurs when creating a group, all previously created groups will be
+ * removed, unwinding everything back to the original state when this
+ * function was called.  It will explicitly warn and error if any of the
+ * attribute files being created already exist.
+ *
+ * Returns 0 on success or error code from sysfs_create_group on failure.
+ */
+int devm_device_add_groups(struct device *dev,
+			   const struct attribute_group **groups)
+{
+	union device_attr_group_devres *devres;
+	int error;
+
+	devres = devres_alloc(devm_attr_groups_remove,
+			      sizeof(*devres), GFP_KERNEL);
+	if (!devres)
+		return -ENOMEM;
+
+	error = sysfs_create_groups(&dev->kobj, groups);
+	if (error) {
+		devres_free(devres);
+		return error;
+	}
+
+	devres->groups = groups;
+	devres_add(dev, devres);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(devm_device_add_groups);
+
+/**
+ * devm_device_remove_groups - remove a list of managed groups
+ *
+ * @dev:	The device for the groups to be removed from
+ * @groups:	NULL terminated list of groups to be removed
+ *
+ * If groups is not NULL, remove the specified groups from the device.
+ */
+void devm_device_remove_groups(struct device *dev,
+			       const struct attribute_group **groups)
+{
+	WARN_ON(devres_release(dev, devm_attr_groups_remove,
+			       devm_attr_group_match,
+			       /* cast away const */ (void *)groups));
+}
+EXPORT_SYMBOL_GPL(devm_device_remove_groups);
+
+static int device_add_attrs(struct device *dev)
+{
+	struct class *class = dev->class;
+	const struct device_type *type = dev->type;
+	int error;
+
+	if (class) {
+		error = device_add_groups(dev, class->dev_groups);
+		if (error)
+			return error;
+	}
+
+	if (type) {
+		error = device_add_groups(dev, type->groups);
+		if (error)
+			goto err_remove_class_groups;
+	}
+
+	error = device_add_groups(dev, dev->groups);
+	if (error)
+		goto err_remove_type_groups;
+
+	if (device_supports_offline(dev) && !dev->offline_disabled) {
+		error = device_create_file(dev, &dev_attr_online);
+		if (error)
+			goto err_remove_dev_groups;
+	}
+
+	if (fw_devlink_flags && !fw_devlink_is_permissive()) {
+		error = device_create_file(dev, &dev_attr_waiting_for_supplier);
+		if (error)
+			goto err_remove_dev_online;
+	}
+
+	if (dev_removable_is_valid(dev)) {
+		error = device_create_file(dev, &dev_attr_removable);
+		if (error)
+			goto err_remove_dev_waiting_for_supplier;
+	}
+
+	return 0;
+
+ err_remove_dev_waiting_for_supplier:
+	device_remove_file(dev, &dev_attr_waiting_for_supplier);
+ err_remove_dev_online:
+	device_remove_file(dev, &dev_attr_online);
+ err_remove_dev_groups:
+	device_remove_groups(dev, dev->groups);
+ err_remove_type_groups:
+	if (type)
+		device_remove_groups(dev, type->groups);
+ err_remove_class_groups:
+	if (class)
+		device_remove_groups(dev, class->dev_groups);
+
+	return error;
+}
+
+static void device_remove_attrs(struct device *dev)
+{
+	struct class *class = dev->class;
+	const struct device_type *type = dev->type;
+
+	device_remove_file(dev, &dev_attr_removable);
+	device_remove_file(dev, &dev_attr_waiting_for_supplier);
+	device_remove_file(dev, &dev_attr_online);
+	device_remove_groups(dev, dev->groups);
+
+	if (type)
+		device_remove_groups(dev, type->groups);
+
+	if (class)
+		device_remove_groups(dev, class->dev_groups);
+}
+
+static ssize_t dev_show(struct device *dev, struct device_attribute *attr,
+			char *buf)
+{
+	return print_dev_t(buf, dev->devt);
+}
+static DEVICE_ATTR_RO(dev);
+
+/* /sys/devices/ */
+struct kset *devices_kset;
+
+/**
+ * devices_kset_move_before - Move device in the devices_kset's list.
+ * @deva: Device to move.
+ * @devb: Device @deva should come before.
+ */
+static void devices_kset_move_before(struct device *deva, struct device *devb)
+{
+	if (!devices_kset)
+		return;
+	pr_debug("devices_kset: Moving %s before %s\n",
+		 dev_name(deva), dev_name(devb));
+	spin_lock(&devices_kset->list_lock);
+	list_move_tail(&deva->kobj.entry, &devb->kobj.entry);
+	spin_unlock(&devices_kset->list_lock);
+}
+
+/**
+ * devices_kset_move_after - Move device in the devices_kset's list.
+ * @deva: Device to move
+ * @devb: Device @deva should come after.
+ */
+static void devices_kset_move_after(struct device *deva, struct device *devb)
+{
+	if (!devices_kset)
+		return;
+	pr_debug("devices_kset: Moving %s after %s\n",
+		 dev_name(deva), dev_name(devb));
+	spin_lock(&devices_kset->list_lock);
+	list_move(&deva->kobj.entry, &devb->kobj.entry);
+	spin_unlock(&devices_kset->list_lock);
+}
+
+/**
+ * devices_kset_move_last - move the device to the end of devices_kset's list.
+ * @dev: device to move
+ */
+void devices_kset_move_last(struct device *dev)
+{
+	if (!devices_kset)
+		return;
+	pr_debug("devices_kset: Moving %s to end of list\n", dev_name(dev));
+	spin_lock(&devices_kset->list_lock);
+	list_move_tail(&dev->kobj.entry, &devices_kset->list);
+	spin_unlock(&devices_kset->list_lock);
+}
+
+/**
+ * device_create_file - create sysfs attribute file for device.
+ * @dev: device.
+ * @attr: device attribute descriptor.
+ */
+int device_create_file(struct device *dev,
+		       const struct device_attribute *attr)
+{
+	int error = 0;
+
+	if (dev) {
+		WARN(((attr->attr.mode & S_IWUGO) && !attr->store),
+			"Attribute %s: write permission without 'store'\n",
+			attr->attr.name);
+		WARN(((attr->attr.mode & S_IRUGO) && !attr->show),
+			"Attribute %s: read permission without 'show'\n",
+			attr->attr.name);
+		error = sysfs_create_file(&dev->kobj, &attr->attr);
+	}
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(device_create_file);
+
+/**
+ * device_remove_file - remove sysfs attribute file.
+ * @dev: device.
+ * @attr: device attribute descriptor.
+ */
+void device_remove_file(struct device *dev,
+			const struct device_attribute *attr)
+{
+	if (dev)
+		sysfs_remove_file(&dev->kobj, &attr->attr);
+}
+EXPORT_SYMBOL_GPL(device_remove_file);
+
+/**
+ * device_remove_file_self - remove sysfs attribute file from its own method.
+ * @dev: device.
+ * @attr: device attribute descriptor.
+ *
+ * See kernfs_remove_self() for details.
+ */
+bool device_remove_file_self(struct device *dev,
+			     const struct device_attribute *attr)
+{
+	if (dev)
+		return sysfs_remove_file_self(&dev->kobj, &attr->attr);
+	else
+		return false;
+}
+EXPORT_SYMBOL_GPL(device_remove_file_self);
+
+/**
+ * device_create_bin_file - create sysfs binary attribute file for device.
+ * @dev: device.
+ * @attr: device binary attribute descriptor.
+ */
+int device_create_bin_file(struct device *dev,
+			   const struct bin_attribute *attr)
+{
+	int error = -EINVAL;
+	if (dev)
+		error = sysfs_create_bin_file(&dev->kobj, attr);
+	return error;
+}
+EXPORT_SYMBOL_GPL(device_create_bin_file);
+
+/**
+ * device_remove_bin_file - remove sysfs binary attribute file
+ * @dev: device.
+ * @attr: device binary attribute descriptor.
+ */
+void device_remove_bin_file(struct device *dev,
+			    const struct bin_attribute *attr)
+{
+	if (dev)
+		sysfs_remove_bin_file(&dev->kobj, attr);
+}
+EXPORT_SYMBOL_GPL(device_remove_bin_file);
+
+static void klist_children_get(struct klist_node *n)
+{
+	struct device_private *p = to_device_private_parent(n);
+	struct device *dev = p->device;
+
+	get_device(dev);
+}
+
+static void klist_children_put(struct klist_node *n)
+{
+	struct device_private *p = to_device_private_parent(n);
+	struct device *dev = p->device;
+
+	put_device(dev);
+}
+
+/**
+ * device_initialize - init device structure.
+ * @dev: device.
+ *
+ * This prepares the device for use by other layers by initializing
+ * its fields.
+ * It is the first half of device_register(), if called by
+ * that function, though it can also be called separately, so one
+ * may use @dev's fields. In particular, get_device()/put_device()
+ * may be used for reference counting of @dev after calling this
+ * function.
+ *
+ * All fields in @dev must be initialized by the caller to 0, except
+ * for those explicitly set to some other value.  The simplest
+ * approach is to use kzalloc() to allocate the structure containing
+ * @dev.
+ *
+ * NOTE: Use put_device() to give up your reference instead of freeing
+ * @dev directly once you have called this function.
+ */
+void device_initialize(struct device *dev)
+{
+	dev->kobj.kset = devices_kset;
+	kobject_init(&dev->kobj, &device_ktype);
+	INIT_LIST_HEAD(&dev->dma_pools);
+	mutex_init(&dev->mutex);
+#ifdef CONFIG_PROVE_LOCKING
+	mutex_init(&dev->lockdep_mutex);
+#endif
+	lockdep_set_novalidate_class(&dev->mutex);
+	spin_lock_init(&dev->devres_lock);
+	INIT_LIST_HEAD(&dev->devres_head);
+	device_pm_init(dev);
+	set_dev_node(dev, -1);
+#ifdef CONFIG_GENERIC_MSI_IRQ
+	raw_spin_lock_init(&dev->msi_lock);
+	INIT_LIST_HEAD(&dev->msi_list);
+#endif
+	INIT_LIST_HEAD(&dev->links.consumers);
+	INIT_LIST_HEAD(&dev->links.suppliers);
+	INIT_LIST_HEAD(&dev->links.needs_suppliers);
+	INIT_LIST_HEAD(&dev->links.defer_hook);
+	dev->links.status = DL_DEV_NO_DRIVER;
+}
+EXPORT_SYMBOL_GPL(device_initialize);
+
+struct kobject *virtual_device_parent(struct device *dev)
+{
+	static struct kobject *virtual_dir = NULL;
+
+	if (!virtual_dir)
+		virtual_dir = kobject_create_and_add("virtual",
+						     &devices_kset->kobj);
+
+	return virtual_dir;
+}
+
+struct class_dir {
+	struct kobject kobj;
+	struct class *class;
+};
+
+#define to_class_dir(obj) container_of(obj, struct class_dir, kobj)
+
+static void class_dir_release(struct kobject *kobj)
+{
+	struct class_dir *dir = to_class_dir(kobj);
+	kfree(dir);
+}
+
+static const
+struct kobj_ns_type_operations *class_dir_child_ns_type(struct kobject *kobj)
+{
+	struct class_dir *dir = to_class_dir(kobj);
+	return dir->class->ns_type;
+}
+
+static struct kobj_type class_dir_ktype = {
+	.release	= class_dir_release,
+	.sysfs_ops	= &kobj_sysfs_ops,
+	.child_ns_type	= class_dir_child_ns_type
+};
+
+static struct kobject *
+class_dir_create_and_add(struct class *class, struct kobject *parent_kobj)
+{
+	struct class_dir *dir;
+	int retval;
+
+	dir = kzalloc(sizeof(*dir), GFP_KERNEL);
+	if (!dir)
+		return ERR_PTR(-ENOMEM);
+
+	dir->class = class;
+	kobject_init(&dir->kobj, &class_dir_ktype);
+
+	dir->kobj.kset = &class->p->glue_dirs;
+
+	retval = kobject_add(&dir->kobj, parent_kobj, "%s", class->name);
+	if (retval < 0) {
+		kobject_put(&dir->kobj);
+		return ERR_PTR(retval);
+	}
+	return &dir->kobj;
+}
+
+static DEFINE_MUTEX(gdp_mutex);
+
+static struct kobject *get_device_parent(struct device *dev,
+					 struct device *parent)
+{
+	if (dev->class) {
+		struct kobject *kobj = NULL;
+		struct kobject *parent_kobj;
+		struct kobject *k;
+
+#ifdef CONFIG_BLOCK
+		/* block disks show up in /sys/block */
+		if (sysfs_deprecated && dev->class == &block_class) {
+			if (parent && parent->class == &block_class)
+				return &parent->kobj;
+			return &block_class.p->subsys.kobj;
+		}
+#endif
+
+		/*
+		 * If we have no parent, we live in "virtual".
+		 * Class-devices with a non class-device as parent, live
+		 * in a "glue" directory to prevent namespace collisions.
+		 */
+		if (parent == NULL)
+			parent_kobj = virtual_device_parent(dev);
+		else if (parent->class && !dev->class->ns_type)
+			return &parent->kobj;
+		else
+			parent_kobj = &parent->kobj;
+
+		mutex_lock(&gdp_mutex);
+
+		/* find our class-directory at the parent and reference it */
+		spin_lock(&dev->class->p->glue_dirs.list_lock);
+		list_for_each_entry(k, &dev->class->p->glue_dirs.list, entry)
+			if (k->parent == parent_kobj) {
+				kobj = kobject_get(k);
+				break;
+			}
+		spin_unlock(&dev->class->p->glue_dirs.list_lock);
+		if (kobj) {
+			mutex_unlock(&gdp_mutex);
+			return kobj;
+		}
+
+		/* or create a new class-directory at the parent device */
+		k = class_dir_create_and_add(dev->class, parent_kobj);
+		/* do not emit an uevent for this simple "glue" directory */
+		mutex_unlock(&gdp_mutex);
+		return k;
+	}
+
+	/* subsystems can specify a default root directory for their devices */
+	if (!parent && dev->bus && dev->bus->dev_root)
+		return &dev->bus->dev_root->kobj;
+
+	if (parent)
+		return &parent->kobj;
+	return NULL;
+}
+
+static inline bool live_in_glue_dir(struct kobject *kobj,
+				    struct device *dev)
+{
+	if (!kobj || !dev->class ||
+	    kobj->kset != &dev->class->p->glue_dirs)
+		return false;
+	return true;
+}
+
+static inline struct kobject *get_glue_dir(struct device *dev)
+{
+	return dev->kobj.parent;
+}
+
+/*
+ * make sure cleaning up dir as the last step, we need to make
+ * sure .release handler of kobject is run with holding the
+ * global lock
+ */
+static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir)
+{
+	unsigned int ref;
+
+	/* see if we live in a "glue" directory */
+	if (!live_in_glue_dir(glue_dir, dev))
+		return;
+
+	mutex_lock(&gdp_mutex);
+	/**
+	 * There is a race condition between removing glue directory
+	 * and adding a new device under the glue directory.
+	 *
+	 * CPU1:                                         CPU2:
+	 *
+	 * device_add()
+	 *   get_device_parent()
+	 *     class_dir_create_and_add()
+	 *       kobject_add_internal()
+	 *         create_dir()    // create glue_dir
+	 *
+	 *                                               device_add()
+	 *                                                 get_device_parent()
+	 *                                                   kobject_get() // get glue_dir
+	 *
+	 * device_del()
+	 *   cleanup_glue_dir()
+	 *     kobject_del(glue_dir)
+	 *
+	 *                                               kobject_add()
+	 *                                                 kobject_add_internal()
+	 *                                                   create_dir() // in glue_dir
+	 *                                                     sysfs_create_dir_ns()
+	 *                                                       kernfs_create_dir_ns(sd)
+	 *
+	 *       sysfs_remove_dir() // glue_dir->sd=NULL
+	 *       sysfs_put()        // free glue_dir->sd
+	 *
+	 *                                                         // sd is freed
+	 *                                                         kernfs_new_node(sd)
+	 *                                                           kernfs_get(glue_dir)
+	 *                                                           kernfs_add_one()
+	 *                                                           kernfs_put()
+	 *
+	 * Before CPU1 remove last child device under glue dir, if CPU2 add
+	 * a new device under glue dir, the glue_dir kobject reference count
+	 * will be increase to 2 in kobject_get(k). And CPU2 has been called
+	 * kernfs_create_dir_ns(). Meanwhile, CPU1 call sysfs_remove_dir()
+	 * and sysfs_put(). This result in glue_dir->sd is freed.
+	 *
+	 * Then the CPU2 will see a stale "empty" but still potentially used
+	 * glue dir around in kernfs_new_node().
+	 *
+	 * In order to avoid this happening, we also should make sure that
+	 * kernfs_node for glue_dir is released in CPU1 only when refcount
+	 * for glue_dir kobj is 1.
+	 */
+	ref = kref_read(&glue_dir->kref);
+	if (!kobject_has_children(glue_dir) && !--ref)
+		kobject_del(glue_dir);
+	kobject_put(glue_dir);
+	mutex_unlock(&gdp_mutex);
+}
+
+static int device_add_class_symlinks(struct device *dev)
+{
+	struct device_node *of_node = dev_of_node(dev);
+	int error;
+
+	if (of_node) {
+		error = sysfs_create_link(&dev->kobj, of_node_kobj(of_node), "of_node");
+		if (error)
+			dev_warn(dev, "Error %d creating of_node link\n",error);
+		/* An error here doesn't warrant bringing down the device */
+	}
+
+	if (!dev->class)
+		return 0;
+
+	error = sysfs_create_link(&dev->kobj,
+				  &dev->class->p->subsys.kobj,
+				  "subsystem");
+	if (error)
+		goto out_devnode;
+
+	if (dev->parent && device_is_not_partition(dev)) {
+		error = sysfs_create_link(&dev->kobj, &dev->parent->kobj,
+					  "device");
+		if (error)
+			goto out_subsys;
+	}
+
+#ifdef CONFIG_BLOCK
+	/* /sys/block has directories and does not need symlinks */
+	if (sysfs_deprecated && dev->class == &block_class)
+		return 0;
+#endif
+
+	/* link in the class directory pointing to the device */
+	error = sysfs_create_link(&dev->class->p->subsys.kobj,
+				  &dev->kobj, dev_name(dev));
+	if (error)
+		goto out_device;
+
+	return 0;
+
+out_device:
+	sysfs_remove_link(&dev->kobj, "device");
+
+out_subsys:
+	sysfs_remove_link(&dev->kobj, "subsystem");
+out_devnode:
+	sysfs_remove_link(&dev->kobj, "of_node");
+	return error;
+}
+
+static void device_remove_class_symlinks(struct device *dev)
+{
+	if (dev_of_node(dev))
+		sysfs_remove_link(&dev->kobj, "of_node");
+
+	if (!dev->class)
+		return;
+
+	if (dev->parent && device_is_not_partition(dev))
+		sysfs_remove_link(&dev->kobj, "device");
+	sysfs_remove_link(&dev->kobj, "subsystem");
+#ifdef CONFIG_BLOCK
+	if (sysfs_deprecated && dev->class == &block_class)
+		return;
+#endif
+	sysfs_delete_link(&dev->class->p->subsys.kobj, &dev->kobj, dev_name(dev));
+}
+
+/**
+ * dev_set_name - set a device name
+ * @dev: device
+ * @fmt: format string for the device's name
+ */
+int dev_set_name(struct device *dev, const char *fmt, ...)
+{
+	va_list vargs;
+	int err;
+
+	va_start(vargs, fmt);
+	err = kobject_set_name_vargs(&dev->kobj, fmt, vargs);
+	va_end(vargs);
+	return err;
+}
+EXPORT_SYMBOL_GPL(dev_set_name);
+
+/**
+ * device_to_dev_kobj - select a /sys/dev/ directory for the device
+ * @dev: device
+ *
+ * By default we select char/ for new entries.  Setting class->dev_obj
+ * to NULL prevents an entry from being created.  class->dev_kobj must
+ * be set (or cleared) before any devices are registered to the class
+ * otherwise device_create_sys_dev_entry() and
+ * device_remove_sys_dev_entry() will disagree about the presence of
+ * the link.
+ */
+static struct kobject *device_to_dev_kobj(struct device *dev)
+{
+	struct kobject *kobj;
+
+	if (dev->class)
+		kobj = dev->class->dev_kobj;
+	else
+		kobj = sysfs_dev_char_kobj;
+
+	return kobj;
+}
+
+static int device_create_sys_dev_entry(struct device *dev)
+{
+	struct kobject *kobj = device_to_dev_kobj(dev);
+	int error = 0;
+	char devt_str[15];
+
+	if (kobj) {
+		format_dev_t(devt_str, dev->devt);
+		error = sysfs_create_link(kobj, &dev->kobj, devt_str);
+	}
+
+	return error;
+}
+
+static void device_remove_sys_dev_entry(struct device *dev)
+{
+	struct kobject *kobj = device_to_dev_kobj(dev);
+	char devt_str[15];
+
+	if (kobj) {
+		format_dev_t(devt_str, dev->devt);
+		sysfs_remove_link(kobj, devt_str);
+	}
+}
+
+static int device_private_init(struct device *dev)
+{
+	dev->p = kzalloc(sizeof(*dev->p), GFP_KERNEL);
+	if (!dev->p)
+		return -ENOMEM;
+	dev->p->device = dev;
+	klist_init(&dev->p->klist_children, klist_children_get,
+		   klist_children_put);
+	INIT_LIST_HEAD(&dev->p->deferred_probe);
+	return 0;
+}
+
+/**
+ * device_add - add device to device hierarchy.
+ * @dev: device.
+ *
+ * This is part 2 of device_register(), though may be called
+ * separately _iff_ device_initialize() has been called separately.
+ *
+ * This adds @dev to the kobject hierarchy via kobject_add(), adds it
+ * to the global and sibling lists for the device, then
+ * adds it to the other relevant subsystems of the driver model.
+ *
+ * Do not call this routine or device_register() more than once for
+ * any device structure.  The driver model core is not designed to work
+ * with devices that get unregistered and then spring back to life.
+ * (Among other things, it's very hard to guarantee that all references
+ * to the previous incarnation of @dev have been dropped.)  Allocate
+ * and register a fresh new struct device instead.
+ *
+ * NOTE: _Never_ directly free @dev after calling this function, even
+ * if it returned an error! Always use put_device() to give up your
+ * reference instead.
+ *
+ * Rule of thumb is: if device_add() succeeds, you should call
+ * device_del() when you want to get rid of it. If device_add() has
+ * *not* succeeded, use *only* put_device() to drop the reference
+ * count.
+ */
+int device_add(struct device *dev)
+{
+	struct device *parent;
+	struct kobject *kobj;
+	struct class_interface *class_intf;
+	int error = -EINVAL;
+	struct kobject *glue_dir = NULL;
+
+	dev = get_device(dev);
+	if (!dev)
+		goto done;
+
+	if (!dev->p) {
+		error = device_private_init(dev);
+		if (error)
+			goto done;
+	}
+
+	/*
+	 * for statically allocated devices, which should all be converted
+	 * some day, we need to initialize the name. We prevent reading back
+	 * the name, and force the use of dev_name()
+	 */
+	if (dev->init_name) {
+		dev_set_name(dev, "%s", dev->init_name);
+		dev->init_name = NULL;
+	}
+
+	/* subsystems can specify simple device enumeration */
+	if (!dev_name(dev) && dev->bus && dev->bus->dev_name)
+		dev_set_name(dev, "%s%u", dev->bus->dev_name, dev->id);
+
+	if (!dev_name(dev)) {
+		error = -EINVAL;
+		goto name_error;
+	}
+
+	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
+
+	parent = get_device(dev->parent);
+	kobj = get_device_parent(dev, parent);
+	if (IS_ERR(kobj)) {
+		error = PTR_ERR(kobj);
+		goto parent_error;
+	}
+	if (kobj)
+		dev->kobj.parent = kobj;
+
+	/* use parent numa_node */
+	if (parent && (dev_to_node(dev) == NUMA_NO_NODE))
+		set_dev_node(dev, dev_to_node(parent));
+
+	/* first, register with generic layer. */
+	/* we require the name to be set before, and pass NULL */
+	error = kobject_add(&dev->kobj, dev->kobj.parent, NULL);
+	if (error) {
+		glue_dir = get_glue_dir(dev);
+		goto Error;
+	}
+
+	/* notify platform of device entry */
+	error = device_platform_notify(dev, KOBJ_ADD);
+	if (error)
+		goto platform_error;
+
+	error = device_create_file(dev, &dev_attr_uevent);
+	if (error)
+		goto attrError;
+
+	error = device_add_class_symlinks(dev);
+	if (error)
+		goto SymlinkError;
+	error = device_add_attrs(dev);
+	if (error)
+		goto AttrsError;
+	error = bus_add_device(dev);
+	if (error)
+		goto BusError;
+	error = dpm_sysfs_add(dev);
+	if (error)
+		goto DPMError;
+	device_pm_add(dev);
+
+	if (MAJOR(dev->devt)) {
+		error = device_create_file(dev, &dev_attr_dev);
+		if (error)
+			goto DevAttrError;
+
+		error = device_create_sys_dev_entry(dev);
+		if (error)
+			goto SysEntryError;
+
+		devtmpfs_create_node(dev);
+	}
+
+	/* Notify clients of device addition.  This call must come
+	 * after dpm_sysfs_add() and before kobject_uevent().
+	 */
+	if (dev->bus)
+		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
+					     BUS_NOTIFY_ADD_DEVICE, dev);
+
+	kobject_uevent(&dev->kobj, KOBJ_ADD);
+
+	/*
+	 * Check if any of the other devices (consumers) have been waiting for
+	 * this device (supplier) to be added so that they can create a device
+	 * link to it.
+	 *
+	 * This needs to happen after device_pm_add() because device_link_add()
+	 * requires the supplier be registered before it's called.
+	 *
+	 * But this also needs to happen before bus_probe_device() to make sure
+	 * waiting consumers can link to it before the driver is bound to the
+	 * device and the driver sync_state callback is called for this device.
+	 */
+	if (dev->fwnode && !dev->fwnode->dev) {
+		dev->fwnode->dev = dev;
+		fw_devlink_link_device(dev);
+	}
+
+	bus_probe_device(dev);
+	if (parent)
+		klist_add_tail(&dev->p->knode_parent,
+			       &parent->p->klist_children);
+
+	if (dev->class) {
+		mutex_lock(&dev->class->p->mutex);
+		/* tie the class to the device */
+		klist_add_tail(&dev->p->knode_class,
+			       &dev->class->p->klist_devices);
+
+		/* notify any interfaces that the device is here */
+		list_for_each_entry(class_intf,
+				    &dev->class->p->interfaces, node)
+			if (class_intf->add_dev)
+				class_intf->add_dev(dev, class_intf);
+		mutex_unlock(&dev->class->p->mutex);
+	}
+done:
+	put_device(dev);
+	return error;
+ SysEntryError:
+	if (MAJOR(dev->devt))
+		device_remove_file(dev, &dev_attr_dev);
+ DevAttrError:
+	device_pm_remove(dev);
+	dpm_sysfs_remove(dev);
+ DPMError:
+	bus_remove_device(dev);
+ BusError:
+	device_remove_attrs(dev);
+ AttrsError:
+	device_remove_class_symlinks(dev);
+ SymlinkError:
+	device_remove_file(dev, &dev_attr_uevent);
+ attrError:
+	device_platform_notify(dev, KOBJ_REMOVE);
+platform_error:
+	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
+	glue_dir = get_glue_dir(dev);
+	kobject_del(&dev->kobj);
+ Error:
+	cleanup_glue_dir(dev, glue_dir);
+parent_error:
+	put_device(parent);
+name_error:
+	kfree(dev->p);
+	dev->p = NULL;
+	goto done;
+}
+EXPORT_SYMBOL_GPL(device_add);
+
+/**
+ * device_register - register a device with the system.
+ * @dev: pointer to the device structure
+ *
+ * This happens in two clean steps - initialize the device
+ * and add it to the system. The two steps can be called
+ * separately, but this is the easiest and most common.
+ * I.e. you should only call the two helpers separately if
+ * have a clearly defined need to use and refcount the device
+ * before it is added to the hierarchy.
+ *
+ * For more information, see the kerneldoc for device_initialize()
+ * and device_add().
+ *
+ * NOTE: _Never_ directly free @dev after calling this function, even
+ * if it returned an error! Always use put_device() to give up the
+ * reference initialized in this function instead.
+ */
+int device_register(struct device *dev)
+{
+	device_initialize(dev);
+	return device_add(dev);
+}
+EXPORT_SYMBOL_GPL(device_register);
+
+/**
+ * get_device - increment reference count for device.
+ * @dev: device.
+ *
+ * This simply forwards the call to kobject_get(), though
+ * we do take care to provide for the case that we get a NULL
+ * pointer passed in.
+ */
+struct device *get_device(struct device *dev)
+{
+	return dev ? kobj_to_dev(kobject_get(&dev->kobj)) : NULL;
+}
+EXPORT_SYMBOL_GPL(get_device);
+
+/**
+ * put_device - decrement reference count.
+ * @dev: device in question.
+ */
+void put_device(struct device *dev)
+{
+	/* might_sleep(); */
+	if (dev)
+		kobject_put(&dev->kobj);
+}
+EXPORT_SYMBOL_GPL(put_device);
+
+bool kill_device(struct device *dev)
+{
+	/*
+	 * Require the device lock and set the "dead" flag to guarantee that
+	 * the update behavior is consistent with the other bitfields near
+	 * it and that we cannot have an asynchronous probe routine trying
+	 * to run while we are tearing out the bus/class/sysfs from
+	 * underneath the device.
+	 */
+	lockdep_assert_held(&dev->mutex);
+
+	if (dev->p->dead)
+		return false;
+	dev->p->dead = true;
+	return true;
+}
+EXPORT_SYMBOL_GPL(kill_device);
+
+/**
+ * device_del - delete device from system.
+ * @dev: device.
+ *
+ * This is the first part of the device unregistration
+ * sequence. This removes the device from the lists we control
+ * from here, has it removed from the other driver model
+ * subsystems it was added to in device_add(), and removes it
+ * from the kobject hierarchy.
+ *
+ * NOTE: this should be called manually _iff_ device_add() was
+ * also called manually.
+ */
+void device_del(struct device *dev)
+{
+	struct device *parent = dev->parent;
+	struct kobject *glue_dir = NULL;
+	struct class_interface *class_intf;
+	unsigned int noio_flag;
+
+	device_lock(dev);
+	kill_device(dev);
+	device_unlock(dev);
+
+	if (dev->fwnode && dev->fwnode->dev == dev)
+		dev->fwnode->dev = NULL;
+
+	/* Notify clients of device removal.  This call must come
+	 * before dpm_sysfs_remove().
+	 */
+	noio_flag = memalloc_noio_save();
+	if (dev->bus)
+		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
+					     BUS_NOTIFY_DEL_DEVICE, dev);
+
+	dpm_sysfs_remove(dev);
+	if (parent)
+		klist_del(&dev->p->knode_parent);
+	if (MAJOR(dev->devt)) {
+		devtmpfs_delete_node(dev);
+		device_remove_sys_dev_entry(dev);
+		device_remove_file(dev, &dev_attr_dev);
+	}
+	if (dev->class) {
+		device_remove_class_symlinks(dev);
+
+		mutex_lock(&dev->class->p->mutex);
+		/* notify any interfaces that the device is now gone */
+		list_for_each_entry(class_intf,
+				    &dev->class->p->interfaces, node)
+			if (class_intf->remove_dev)
+				class_intf->remove_dev(dev, class_intf);
+		/* remove the device from the class list */
+		klist_del(&dev->p->knode_class);
+		mutex_unlock(&dev->class->p->mutex);
+	}
+	device_remove_file(dev, &dev_attr_uevent);
+	device_remove_attrs(dev);
+	bus_remove_device(dev);
+	device_pm_remove(dev);
+	driver_deferred_probe_del(dev);
+	device_platform_notify(dev, KOBJ_REMOVE);
+	device_remove_properties(dev);
+	device_links_purge(dev);
+
+	if (dev->bus)
+		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
+					     BUS_NOTIFY_REMOVED_DEVICE, dev);
+	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
+	glue_dir = get_glue_dir(dev);
+	kobject_del(&dev->kobj);
+	cleanup_glue_dir(dev, glue_dir);
+	memalloc_noio_restore(noio_flag);
+	put_device(parent);
+}
+EXPORT_SYMBOL_GPL(device_del);
+
+/**
+ * device_unregister - unregister device from system.
+ * @dev: device going away.
+ *
+ * We do this in two parts, like we do device_register(). First,
+ * we remove it from all the subsystems with device_del(), then
+ * we decrement the reference count via put_device(). If that
+ * is the final reference count, the device will be cleaned up
+ * via device_release() above. Otherwise, the structure will
+ * stick around until the final reference to the device is dropped.
+ */
+void device_unregister(struct device *dev)
+{
+	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
+	device_del(dev);
+	put_device(dev);
+}
+EXPORT_SYMBOL_GPL(device_unregister);
+
+static struct device *prev_device(struct klist_iter *i)
+{
+	struct klist_node *n = klist_prev(i);
+	struct device *dev = NULL;
+	struct device_private *p;
+
+	if (n) {
+		p = to_device_private_parent(n);
+		dev = p->device;
+	}
+	return dev;
+}
+
+static struct device *next_device(struct klist_iter *i)
+{
+	struct klist_node *n = klist_next(i);
+	struct device *dev = NULL;
+	struct device_private *p;
+
+	if (n) {
+		p = to_device_private_parent(n);
+		dev = p->device;
+	}
+	return dev;
+}
+
+/**
+ * device_get_devnode - path of device node file
+ * @dev: device
+ * @mode: returned file access mode
+ * @uid: returned file owner
+ * @gid: returned file group
+ * @tmp: possibly allocated string
+ *
+ * Return the relative path of a possible device node.
+ * Non-default names may need to allocate a memory to compose
+ * a name. This memory is returned in tmp and needs to be
+ * freed by the caller.
+ */
+const char *device_get_devnode(struct device *dev,
+			       umode_t *mode, kuid_t *uid, kgid_t *gid,
+			       const char **tmp)
+{
+	char *s;
+
+	*tmp = NULL;
+
+	/* the device type may provide a specific name */
+	if (dev->type && dev->type->devnode)
+		*tmp = dev->type->devnode(dev, mode, uid, gid);
+	if (*tmp)
+		return *tmp;
+
+	/* the class may provide a specific name */
+	if (dev->class && dev->class->devnode)
+		*tmp = dev->class->devnode(dev, mode);
+	if (*tmp)
+		return *tmp;
+
+	/* return name without allocation, tmp == NULL */
+	if (strchr(dev_name(dev), '!') == NULL)
+		return dev_name(dev);
+
+	/* replace '!' in the name with '/' */
+	s = kstrdup(dev_name(dev), GFP_KERNEL);
+	if (!s)
+		return NULL;
+	strreplace(s, '!', '/');
+	return *tmp = s;
+}
+
+/**
+ * device_for_each_child - device child iterator.
+ * @parent: parent struct device.
+ * @fn: function to be called for each device.
+ * @data: data for the callback.
+ *
+ * Iterate over @parent's child devices, and call @fn for each,
+ * passing it @data.
+ *
+ * We check the return of @fn each time. If it returns anything
+ * other than 0, we break out and return that value.
+ */
+int device_for_each_child(struct device *parent, void *data,
+			  int (*fn)(struct device *dev, void *data))
+{
+	struct klist_iter i;
+	struct device *child;
+	int error = 0;
+
+	if (!parent->p)
+		return 0;
+
+	klist_iter_init(&parent->p->klist_children, &i);
+	while (!error && (child = next_device(&i)))
+		error = fn(child, data);
+	klist_iter_exit(&i);
+	return error;
+}
+EXPORT_SYMBOL_GPL(device_for_each_child);
+
+/**
+ * device_for_each_child_reverse - device child iterator in reversed order.
+ * @parent: parent struct device.
+ * @fn: function to be called for each device.
+ * @data: data for the callback.
+ *
+ * Iterate over @parent's child devices, and call @fn for each,
+ * passing it @data.
+ *
+ * We check the return of @fn each time. If it returns anything
+ * other than 0, we break out and return that value.
+ */
+int device_for_each_child_reverse(struct device *parent, void *data,
+				  int (*fn)(struct device *dev, void *data))
+{
+	struct klist_iter i;
+	struct device *child;
+	int error = 0;
+
+	if (!parent->p)
+		return 0;
+
+	klist_iter_init(&parent->p->klist_children, &i);
+	while ((child = prev_device(&i)) && !error)
+		error = fn(child, data);
+	klist_iter_exit(&i);
+	return error;
+}
+EXPORT_SYMBOL_GPL(device_for_each_child_reverse);
+
+/**
+ * device_find_child - device iterator for locating a particular device.
+ * @parent: parent struct device
+ * @match: Callback function to check device
+ * @data: Data to pass to match function
+ *
+ * This is similar to the device_for_each_child() 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 and a reference to the
+ * current device can be obtained, 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.
+ */
+struct device *device_find_child(struct device *parent, void *data,
+				 int (*match)(struct device *dev, void *data))
+{
+	struct klist_iter i;
+	struct device *child;
+
+	if (!parent)
+		return NULL;
+
+	klist_iter_init(&parent->p->klist_children, &i);
+	while ((child = next_device(&i)))
+		if (match(child, data) && get_device(child))
+			break;
+	klist_iter_exit(&i);
+	return child;
+}
+EXPORT_SYMBOL_GPL(device_find_child);
+
+/**
+ * device_find_child_by_name - device iterator for locating a child device.
+ * @parent: parent struct device
+ * @name: name of the child device
+ *
+ * This is similar to the device_find_child() function above, but it
+ * returns a reference to a device that has the name @name.
+ *
+ * NOTE: you will need to drop the reference with put_device() after use.
+ */
+struct device *device_find_child_by_name(struct device *parent,
+					 const char *name)
+{
+	struct klist_iter i;
+	struct device *child;
+
+	if (!parent)
+		return NULL;
+
+	klist_iter_init(&parent->p->klist_children, &i);
+	while ((child = next_device(&i)))
+		if (sysfs_streq(dev_name(child), name) && get_device(child))
+			break;
+	klist_iter_exit(&i);
+	return child;
+}
+EXPORT_SYMBOL_GPL(device_find_child_by_name);
+
+int __init devices_init(void)
+{
+	devices_kset = kset_create_and_add("devices", &device_uevent_ops, NULL);
+	if (!devices_kset)
+		return -ENOMEM;
+	dev_kobj = kobject_create_and_add("dev", NULL);
+	if (!dev_kobj)
+		goto dev_kobj_err;
+	sysfs_dev_block_kobj = kobject_create_and_add("block", dev_kobj);
+	if (!sysfs_dev_block_kobj)
+		goto block_kobj_err;
+	sysfs_dev_char_kobj = kobject_create_and_add("char", dev_kobj);
+	if (!sysfs_dev_char_kobj)
+		goto char_kobj_err;
+
+	return 0;
+
+ char_kobj_err:
+	kobject_put(sysfs_dev_block_kobj);
+ block_kobj_err:
+	kobject_put(dev_kobj);
+ dev_kobj_err:
+	kset_unregister(devices_kset);
+	return -ENOMEM;
+}
+
+static int device_check_offline(struct device *dev, void *not_used)
+{
+	int ret;
+
+	ret = device_for_each_child(dev, NULL, device_check_offline);
+	if (ret)
+		return ret;
+
+	return device_supports_offline(dev) && !dev->offline ? -EBUSY : 0;
+}
+
+/**
+ * device_offline - Prepare the device for hot-removal.
+ * @dev: Device to be put offline.
+ *
+ * Execute the device bus type's .offline() callback, if present, to prepare
+ * the device for a subsequent hot-removal.  If that succeeds, the device must
+ * not be used until either it is removed or its bus type's .online() callback
+ * is executed.
+ *
+ * Call under device_hotplug_lock.
+ */
+int device_offline(struct device *dev)
+{
+	int ret;
+
+	if (dev->offline_disabled)
+		return -EPERM;
+
+	ret = device_for_each_child(dev, NULL, device_check_offline);
+	if (ret)
+		return ret;
+
+	device_lock(dev);
+	if (device_supports_offline(dev)) {
+		if (dev->offline) {
+			ret = 1;
+		} else {
+			ret = dev->bus->offline(dev);
+			if (!ret) {
+				kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
+				dev->offline = true;
+			}
+		}
+	}
+	device_unlock(dev);
+
+	return ret;
+}
+
+/**
+ * device_online - Put the device back online after successful device_offline().
+ * @dev: Device to be put back online.
+ *
+ * If device_offline() has been successfully executed for @dev, but the device
+ * has not been removed subsequently, execute its bus type's .online() callback
+ * to indicate that the device can be used again.
+ *
+ * Call under device_hotplug_lock.
+ */
+int device_online(struct device *dev)
+{
+	int ret = 0;
+
+	device_lock(dev);
+	if (device_supports_offline(dev)) {
+		if (dev->offline) {
+			ret = dev->bus->online(dev);
+			if (!ret) {
+				kobject_uevent(&dev->kobj, KOBJ_ONLINE);
+				dev->offline = false;
+			}
+		} else {
+			ret = 1;
+		}
+	}
+	device_unlock(dev);
+
+	return ret;
+}
+
+struct root_device {
+	struct device dev;
+	struct module *owner;
+};
+
+static inline struct root_device *to_root_device(struct device *d)
+{
+	return container_of(d, struct root_device, dev);
+}
+
+static void root_device_release(struct device *dev)
+{
+	kfree(to_root_device(dev));
+}
+
+/**
+ * __root_device_register - allocate and register a root device
+ * @name: root device name
+ * @owner: owner module of the root device, usually THIS_MODULE
+ *
+ * This function allocates a root device and registers it
+ * using device_register(). In order to free the returned
+ * device, use root_device_unregister().
+ *
+ * Root devices are dummy devices which allow other devices
+ * to be grouped under /sys/devices. Use this function to
+ * allocate a root device and then use it as the parent of
+ * any device which should appear under /sys/devices/{name}
+ *
+ * The /sys/devices/{name} directory will also contain a
+ * 'module' symlink which points to the @owner directory
+ * in sysfs.
+ *
+ * Returns &struct device pointer on success, or ERR_PTR() on error.
+ *
+ * Note: You probably want to use root_device_register().
+ */
+struct device *__root_device_register(const char *name, struct module *owner)
+{
+	struct root_device *root;
+	int err = -ENOMEM;
+
+	root = kzalloc(sizeof(struct root_device), GFP_KERNEL);
+	if (!root)
+		return ERR_PTR(err);
+
+	err = dev_set_name(&root->dev, "%s", name);
+	if (err) {
+		kfree(root);
+		return ERR_PTR(err);
+	}
+
+	root->dev.release = root_device_release;
+
+	err = device_register(&root->dev);
+	if (err) {
+		put_device(&root->dev);
+		return ERR_PTR(err);
+	}
+
+#ifdef CONFIG_MODULES	/* gotta find a "cleaner" way to do this */
+	if (owner) {
+		struct module_kobject *mk = &owner->mkobj;
+
+		err = sysfs_create_link(&root->dev.kobj, &mk->kobj, "module");
+		if (err) {
+			device_unregister(&root->dev);
+			return ERR_PTR(err);
+		}
+		root->owner = owner;
+	}
+#endif
+
+	return &root->dev;
+}
+EXPORT_SYMBOL_GPL(__root_device_register);
+
+/**
+ * root_device_unregister - unregister and free a root device
+ * @dev: device going away
+ *
+ * This function unregisters and cleans up a device that was created by
+ * root_device_register().
+ */
+void root_device_unregister(struct device *dev)
+{
+	struct root_device *root = to_root_device(dev);
+
+	if (root->owner)
+		sysfs_remove_link(&root->dev.kobj, "module");
+
+	device_unregister(dev);
+}
+EXPORT_SYMBOL_GPL(root_device_unregister);
+
+
+static void device_create_release(struct device *dev)
+{
+	pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
+	kfree(dev);
+}
+
+static __printf(6, 0) struct device *
+device_create_groups_vargs(struct class *class, struct device *parent,
+			   dev_t devt, void *drvdata,
+			   const struct attribute_group **groups,
+			   const char *fmt, va_list args)
+{
+	struct device *dev = NULL;
+	int retval = -ENODEV;
+
+	if (class == NULL || IS_ERR(class))
+		goto error;
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev) {
+		retval = -ENOMEM;
+		goto error;
+	}
+
+	device_initialize(dev);
+	dev->devt = devt;
+	dev->class = class;
+	dev->parent = parent;
+	dev->groups = groups;
+	dev->release = device_create_release;
+	dev_set_drvdata(dev, drvdata);
+
+	retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
+	if (retval)
+		goto error;
+
+	retval = device_add(dev);
+	if (retval)
+		goto error;
+
+	return dev;
+
+error:
+	put_device(dev);
+	return ERR_PTR(retval);
+}
+
+/**
+ * device_create - creates a device and registers it with sysfs
+ * @class: pointer to the struct class that this device should be registered to
+ * @parent: pointer to the parent struct device of this new device, if any
+ * @devt: the dev_t for the char device to be added
+ * @drvdata: the data to be added to the device for callbacks
+ * @fmt: string for the device's name
+ *
+ * This function can be used by char device classes.  A struct device
+ * will be created in sysfs, registered to the specified class.
+ *
+ * A "dev" file will be created, showing the dev_t for the device, if
+ * the dev_t is not 0,0.
+ * If a pointer to a parent struct device is passed in, the newly created
+ * struct device will be a child of that device in sysfs.
+ * The pointer to the struct device will be returned from the call.
+ * Any further sysfs files that might be required can be created using this
+ * pointer.
+ *
+ * Returns &struct device pointer on success, or ERR_PTR() on error.
+ *
+ * Note: the struct class passed to this function must have previously
+ * been created with a call to class_create().
+ */
+struct device *device_create(struct class *class, struct device *parent,
+			     dev_t devt, void *drvdata, const char *fmt, ...)
+{
+	va_list vargs;
+	struct device *dev;
+
+	va_start(vargs, fmt);
+	dev = device_create_groups_vargs(class, parent, devt, drvdata, NULL,
+					  fmt, vargs);
+	va_end(vargs);
+	return dev;
+}
+EXPORT_SYMBOL_GPL(device_create);
+
+/**
+ * device_create_with_groups - creates a device and registers it with sysfs
+ * @class: pointer to the struct class that this device should be registered to
+ * @parent: pointer to the parent struct device of this new device, if any
+ * @devt: the dev_t for the char device to be added
+ * @drvdata: the data to be added to the device for callbacks
+ * @groups: NULL-terminated list of attribute groups to be created
+ * @fmt: string for the device's name
+ *
+ * This function can be used by char device classes.  A struct device
+ * will be created in sysfs, registered to the specified class.
+ * Additional attributes specified in the groups parameter will also
+ * be created automatically.
+ *
+ * A "dev" file will be created, showing the dev_t for the device, if
+ * the dev_t is not 0,0.
+ * If a pointer to a parent struct device is passed in, the newly created
+ * struct device will be a child of that device in sysfs.
+ * The pointer to the struct device will be returned from the call.
+ * Any further sysfs files that might be required can be created using this
+ * pointer.
+ *
+ * Returns &struct device pointer on success, or ERR_PTR() on error.
+ *
+ * Note: the struct class passed to this function must have previously
+ * been created with a call to class_create().
+ */
+struct device *device_create_with_groups(struct class *class,
+					 struct device *parent, dev_t devt,
+					 void *drvdata,
+					 const struct attribute_group **groups,
+					 const char *fmt, ...)
+{
+	va_list vargs;
+	struct device *dev;
+
+	va_start(vargs, fmt);
+	dev = device_create_groups_vargs(class, parent, devt, drvdata, groups,
+					 fmt, vargs);
+	va_end(vargs);
+	return dev;
+}
+EXPORT_SYMBOL_GPL(device_create_with_groups);
+
+/**
+ * device_destroy - removes a device that was created with device_create()
+ * @class: pointer to the struct class that this device was registered with
+ * @devt: the dev_t of the device that was previously registered
+ *
+ * This call unregisters and cleans up a device that was created with a
+ * call to device_create().
+ */
+void device_destroy(struct class *class, dev_t devt)
+{
+	struct device *dev;
+
+	dev = class_find_device_by_devt(class, devt);
+	if (dev) {
+		put_device(dev);
+		device_unregister(dev);
+	}
+}
+EXPORT_SYMBOL_GPL(device_destroy);
+
+/**
+ * device_rename - renames a device
+ * @dev: the pointer to the struct device to be renamed
+ * @new_name: the new name of the device
+ *
+ * It is the responsibility of the caller to provide mutual
+ * exclusion between two different calls of device_rename
+ * on the same device to ensure that new_name is valid and
+ * won't conflict with other devices.
+ *
+ * Note: Don't call this function.  Currently, the networking layer calls this
+ * function, but that will change.  The following text from Kay Sievers offers
+ * some insight:
+ *
+ * Renaming devices is racy at many levels, symlinks and other stuff are not
+ * replaced atomically, and you get a "move" uevent, but it's not easy to
+ * connect the event to the old and new device. Device nodes are not renamed at
+ * all, there isn't even support for that in the kernel now.
+ *
+ * In the meantime, during renaming, your target name might be taken by another
+ * driver, creating conflicts. Or the old name is taken directly after you
+ * renamed it -- then you get events for the same DEVPATH, before you even see
+ * the "move" event. It's just a mess, and nothing new should ever rely on
+ * kernel device renaming. Besides that, it's not even implemented now for
+ * other things than (driver-core wise very simple) network devices.
+ *
+ * We are currently about to change network renaming in udev to completely
+ * disallow renaming of devices in the same namespace as the kernel uses,
+ * because we can't solve the problems properly, that arise with swapping names
+ * of multiple interfaces without races. Means, renaming of eth[0-9]* will only
+ * be allowed to some other name than eth[0-9]*, for the aforementioned
+ * reasons.
+ *
+ * Make up a "real" name in the driver before you register anything, or add
+ * some other attributes for userspace to find the device, or use udev to add
+ * symlinks -- but never rename kernel devices later, it's a complete mess. We
+ * don't even want to get into that and try to implement the missing pieces in
+ * the core. We really have other pieces to fix in the driver core mess. :)
+ */
+int device_rename(struct device *dev, const char *new_name)
+{
+	struct kobject *kobj = &dev->kobj;
+	char *old_device_name = NULL;
+	int error;
+
+	dev = get_device(dev);
+	if (!dev)
+		return -EINVAL;
+
+	dev_dbg(dev, "renaming to %s\n", new_name);
+
+	old_device_name = kstrdup(dev_name(dev), GFP_KERNEL);
+	if (!old_device_name) {
+		error = -ENOMEM;
+		goto out;
+	}
+
+	if (dev->class) {
+		error = sysfs_rename_link_ns(&dev->class->p->subsys.kobj,
+					     kobj, old_device_name,
+					     new_name, kobject_namespace(kobj));
+		if (error)
+			goto out;
+	}
+
+	error = kobject_rename(kobj, new_name);
+	if (error)
+		goto out;
+
+out:
+	put_device(dev);
+
+	kfree(old_device_name);
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(device_rename);
+
+static int device_move_class_links(struct device *dev,
+				   struct device *old_parent,
+				   struct device *new_parent)
+{
+	int error = 0;
+
+	if (old_parent)
+		sysfs_remove_link(&dev->kobj, "device");
+	if (new_parent)
+		error = sysfs_create_link(&dev->kobj, &new_parent->kobj,
+					  "device");
+	return error;
+}
+
+/**
+ * device_move - moves a device to a new parent
+ * @dev: the pointer to the struct device to be moved
+ * @new_parent: the new parent of the device (can be NULL)
+ * @dpm_order: how to reorder the dpm_list
+ */
+int device_move(struct device *dev, struct device *new_parent,
+		enum dpm_order dpm_order)
+{
+	int error;
+	struct device *old_parent;
+	struct kobject *new_parent_kobj;
+
+	dev = get_device(dev);
+	if (!dev)
+		return -EINVAL;
+
+	device_pm_lock();
+	new_parent = get_device(new_parent);
+	new_parent_kobj = get_device_parent(dev, new_parent);
+	if (IS_ERR(new_parent_kobj)) {
+		error = PTR_ERR(new_parent_kobj);
+		put_device(new_parent);
+		goto out;
+	}
+
+	pr_debug("device: '%s': %s: moving to '%s'\n", dev_name(dev),
+		 __func__, new_parent ? dev_name(new_parent) : "<NULL>");
+	error = kobject_move(&dev->kobj, new_parent_kobj);
+	if (error) {
+		cleanup_glue_dir(dev, new_parent_kobj);
+		put_device(new_parent);
+		goto out;
+	}
+	old_parent = dev->parent;
+	dev->parent = new_parent;
+	if (old_parent)
+		klist_remove(&dev->p->knode_parent);
+	if (new_parent) {
+		klist_add_tail(&dev->p->knode_parent,
+			       &new_parent->p->klist_children);
+		set_dev_node(dev, dev_to_node(new_parent));
+	}
+
+	if (dev->class) {
+		error = device_move_class_links(dev, old_parent, new_parent);
+		if (error) {
+			/* We ignore errors on cleanup since we're hosed anyway... */
+			device_move_class_links(dev, new_parent, old_parent);
+			if (!kobject_move(&dev->kobj, &old_parent->kobj)) {
+				if (new_parent)
+					klist_remove(&dev->p->knode_parent);
+				dev->parent = old_parent;
+				if (old_parent) {
+					klist_add_tail(&dev->p->knode_parent,
+						       &old_parent->p->klist_children);
+					set_dev_node(dev, dev_to_node(old_parent));
+				}
+			}
+			cleanup_glue_dir(dev, new_parent_kobj);
+			put_device(new_parent);
+			goto out;
+		}
+	}
+	switch (dpm_order) {
+	case DPM_ORDER_NONE:
+		break;
+	case DPM_ORDER_DEV_AFTER_PARENT:
+		device_pm_move_after(dev, new_parent);
+		devices_kset_move_after(dev, new_parent);
+		break;
+	case DPM_ORDER_PARENT_BEFORE_DEV:
+		device_pm_move_before(new_parent, dev);
+		devices_kset_move_before(new_parent, dev);
+		break;
+	case DPM_ORDER_DEV_LAST:
+		device_pm_move_last(dev);
+		devices_kset_move_last(dev);
+		break;
+	}
+
+	put_device(old_parent);
+out:
+	device_pm_unlock();
+	put_device(dev);
+	return error;
+}
+EXPORT_SYMBOL_GPL(device_move);
+
+static int device_attrs_change_owner(struct device *dev, kuid_t kuid,
+				     kgid_t kgid)
+{
+	struct kobject *kobj = &dev->kobj;
+	struct class *class = dev->class;
+	const struct device_type *type = dev->type;
+	int error;
+
+	if (class) {
+		/*
+		 * Change the device groups of the device class for @dev to
+		 * @kuid/@kgid.
+		 */
+		error = sysfs_groups_change_owner(kobj, class->dev_groups, kuid,
+						  kgid);
+		if (error)
+			return error;
+	}
+
+	if (type) {
+		/*
+		 * Change the device groups of the device type for @dev to
+		 * @kuid/@kgid.
+		 */
+		error = sysfs_groups_change_owner(kobj, type->groups, kuid,
+						  kgid);
+		if (error)
+			return error;
+	}
+
+	/* Change the device groups of @dev to @kuid/@kgid. */
+	error = sysfs_groups_change_owner(kobj, dev->groups, kuid, kgid);
+	if (error)
+		return error;
+
+	if (device_supports_offline(dev) && !dev->offline_disabled) {
+		/* Change online device attributes of @dev to @kuid/@kgid. */
+		error = sysfs_file_change_owner(kobj, dev_attr_online.attr.name,
+						kuid, kgid);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
+/**
+ * device_change_owner - change the owner of an existing device.
+ * @dev: device.
+ * @kuid: new owner's kuid
+ * @kgid: new owner's kgid
+ *
+ * This changes the owner of @dev and its corresponding sysfs entries to
+ * @kuid/@kgid. This function closely mirrors how @dev was added via driver
+ * core.
+ *
+ * Returns 0 on success or error code on failure.
+ */
+int device_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)
+{
+	int error;
+	struct kobject *kobj = &dev->kobj;
+
+	dev = get_device(dev);
+	if (!dev)
+		return -EINVAL;
+
+	/*
+	 * Change the kobject and the default attributes and groups of the
+	 * ktype associated with it to @kuid/@kgid.
+	 */
+	error = sysfs_change_owner(kobj, kuid, kgid);
+	if (error)
+		goto out;
+
+	/*
+	 * Change the uevent file for @dev to the new owner. The uevent file
+	 * was created in a separate step when @dev got added and we mirror
+	 * that step here.
+	 */
+	error = sysfs_file_change_owner(kobj, dev_attr_uevent.attr.name, kuid,
+					kgid);
+	if (error)
+		goto out;
+
+	/*
+	 * Change the device groups, the device groups associated with the
+	 * device class, and the groups associated with the device type of @dev
+	 * to @kuid/@kgid.
+	 */
+	error = device_attrs_change_owner(dev, kuid, kgid);
+	if (error)
+		goto out;
+
+	error = dpm_sysfs_change_owner(dev, kuid, kgid);
+	if (error)
+		goto out;
+
+#ifdef CONFIG_BLOCK
+	if (sysfs_deprecated && dev->class == &block_class)
+		goto out;
+#endif
+
+	/*
+	 * Change the owner of the symlink located in the class directory of
+	 * the device class associated with @dev which points to the actual
+	 * directory entry for @dev to @kuid/@kgid. This ensures that the
+	 * symlink shows the same permissions as its target.
+	 */
+	error = sysfs_link_change_owner(&dev->class->p->subsys.kobj, &dev->kobj,
+					dev_name(dev), kuid, kgid);
+	if (error)
+		goto out;
+
+out:
+	put_device(dev);
+	return error;
+}
+EXPORT_SYMBOL_GPL(device_change_owner);
+
+/**
+ * device_shutdown - call ->shutdown() on each device to shutdown.
+ */
+void device_shutdown(void)
+{
+	struct device *dev, *parent;
+
+	wait_for_device_probe();
+	device_block_probing();
+
+	cpufreq_suspend();
+
+	spin_lock(&devices_kset->list_lock);
+	/*
+	 * Walk the devices list backward, shutting down each in turn.
+	 * Beware that device unplug events may also start pulling
+	 * devices offline, even as the system is shutting down.
+	 */
+	while (!list_empty(&devices_kset->list)) {
+		dev = list_entry(devices_kset->list.prev, struct device,
+				kobj.entry);
+
+		/*
+		 * hold reference count of device's parent to
+		 * prevent it from being freed because parent's
+		 * lock is to be held
+		 */
+		parent = get_device(dev->parent);
+		get_device(dev);
+		/*
+		 * Make sure the device is off the kset list, in the
+		 * event that dev->*->shutdown() doesn't remove it.
+		 */
+		list_del_init(&dev->kobj.entry);
+		spin_unlock(&devices_kset->list_lock);
+
+		/* hold lock to avoid race with probe/release */
+		if (parent)
+			device_lock(parent);
+		device_lock(dev);
+
+		/* Don't allow any more runtime suspends */
+		pm_runtime_get_noresume(dev);
+		pm_runtime_barrier(dev);
+
+		if (dev->class && dev->class->shutdown_pre) {
+			if (initcall_debug)
+				dev_info(dev, "shutdown_pre\n");
+			dev->class->shutdown_pre(dev);
+		}
+		if (dev->bus && dev->bus->shutdown) {
+			if (initcall_debug)
+				dev_info(dev, "shutdown\n");
+			dev->bus->shutdown(dev);
+		} else if (dev->driver && dev->driver->shutdown) {
+			if (initcall_debug)
+				dev_info(dev, "shutdown\n");
+			dev->driver->shutdown(dev);
+		}
+
+		device_unlock(dev);
+		if (parent)
+			device_unlock(parent);
+
+		put_device(dev);
+		put_device(parent);
+
+		spin_lock(&devices_kset->list_lock);
+	}
+	spin_unlock(&devices_kset->list_lock);
+}
+
+/*
+ * Device logging functions
+ */
+
+#ifdef CONFIG_PRINTK
+static void
+set_dev_info(const struct device *dev, struct dev_printk_info *dev_info)
+{
+	const char *subsys;
+
+	memset(dev_info, 0, sizeof(*dev_info));
+
+	if (dev->class)
+		subsys = dev->class->name;
+	else if (dev->bus)
+		subsys = dev->bus->name;
+	else
+		return;
+
+	strscpy(dev_info->subsystem, subsys, sizeof(dev_info->subsystem));
+
+	/*
+	 * Add device identifier DEVICE=:
+	 *   b12:8         block dev_t
+	 *   c127:3        char dev_t
+	 *   n8            netdev ifindex
+	 *   +sound:card0  subsystem:devname
+	 */
+	if (MAJOR(dev->devt)) {
+		char c;
+
+		if (strcmp(subsys, "block") == 0)
+			c = 'b';
+		else
+			c = 'c';
+
+		snprintf(dev_info->device, sizeof(dev_info->device),
+			 "%c%u:%u", c, MAJOR(dev->devt), MINOR(dev->devt));
+	} else if (strcmp(subsys, "net") == 0) {
+		struct net_device *net = to_net_dev(dev);
+
+		snprintf(dev_info->device, sizeof(dev_info->device),
+			 "n%u", net->ifindex);
+	} else {
+		snprintf(dev_info->device, sizeof(dev_info->device),
+			 "+%s:%s", subsys, dev_name(dev));
+	}
+}
+
+int dev_vprintk_emit(int level, const struct device *dev,
+		     const char *fmt, va_list args)
+{
+	struct dev_printk_info dev_info;
+
+	set_dev_info(dev, &dev_info);
+
+	return vprintk_emit(0, level, &dev_info, fmt, args);
+}
+EXPORT_SYMBOL(dev_vprintk_emit);
+
+int dev_printk_emit(int level, const struct device *dev, const char *fmt, ...)
+{
+	va_list args;
+	int r;
+
+	va_start(args, fmt);
+
+	r = dev_vprintk_emit(level, dev, fmt, args);
+
+	va_end(args);
+
+	return r;
+}
+EXPORT_SYMBOL(dev_printk_emit);
+
+static void __dev_printk(const char *level, const struct device *dev,
+			struct va_format *vaf)
+{
+	if (dev)
+		dev_printk_emit(level[1] - '0', dev, "%s %s: %pV",
+				dev_driver_string(dev), dev_name(dev), vaf);
+	else
+		printk("%s(NULL device *): %pV", level, vaf);
+}
+
+void dev_printk(const char *level, const struct device *dev,
+		const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	__dev_printk(level, dev, &vaf);
+
+	va_end(args);
+}
+EXPORT_SYMBOL(dev_printk);
+
+#define define_dev_printk_level(func, kern_level)		\
+void func(const struct device *dev, const char *fmt, ...)	\
+{								\
+	struct va_format vaf;					\
+	va_list args;						\
+								\
+	va_start(args, fmt);					\
+								\
+	vaf.fmt = fmt;						\
+	vaf.va = &args;						\
+								\
+	__dev_printk(kern_level, dev, &vaf);			\
+								\
+	va_end(args);						\
+}								\
+EXPORT_SYMBOL(func);
+
+define_dev_printk_level(_dev_emerg, KERN_EMERG);
+define_dev_printk_level(_dev_alert, KERN_ALERT);
+define_dev_printk_level(_dev_crit, KERN_CRIT);
+define_dev_printk_level(_dev_err, KERN_ERR);
+define_dev_printk_level(_dev_warn, KERN_WARNING);
+define_dev_printk_level(_dev_notice, KERN_NOTICE);
+define_dev_printk_level(_dev_info, KERN_INFO);
+
+#endif
+
+/**
+ * dev_err_probe - probe error check and log helper
+ * @dev: the pointer to the struct device
+ * @err: error value to test
+ * @fmt: printf-style format string
+ * @...: arguments as specified in the format string
+ *
+ * This helper implements common pattern present in probe functions for error
+ * checking: print debug or error message depending if the error value is
+ * -EPROBE_DEFER and propagate error upwards.
+ * In case of -EPROBE_DEFER it sets also defer probe reason, which can be
+ * checked later by reading devices_deferred debugfs attribute.
+ * It replaces code sequence::
+ *
+ * 	if (err != -EPROBE_DEFER)
+ * 		dev_err(dev, ...);
+ * 	else
+ * 		dev_dbg(dev, ...);
+ * 	return err;
+ *
+ * with::
+ *
+ * 	return dev_err_probe(dev, err, ...);
+ *
+ * Returns @err.
+ *
+ */
+int dev_err_probe(const struct device *dev, int err, const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	if (err != -EPROBE_DEFER) {
+		dev_err(dev, "error %pe: %pV", ERR_PTR(err), &vaf);
+	} else {
+		device_set_deferred_probe_reason(dev, &vaf);
+		dev_dbg(dev, "error %pe: %pV", ERR_PTR(err), &vaf);
+	}
+
+	va_end(args);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(dev_err_probe);
+
+static inline bool fwnode_is_primary(struct fwnode_handle *fwnode)
+{
+	return fwnode && !IS_ERR(fwnode->secondary);
+}
+
+/**
+ * set_primary_fwnode - Change the primary firmware node of a given device.
+ * @dev: Device to handle.
+ * @fwnode: New primary firmware node of the device.
+ *
+ * Set the device's firmware node pointer to @fwnode, but if a secondary
+ * firmware node of the device is present, preserve it.
+ */
+void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
+{
+	struct device *parent = dev->parent;
+	struct fwnode_handle *fn = dev->fwnode;
+
+	if (fwnode) {
+		if (fwnode_is_primary(fn))
+			fn = fn->secondary;
+
+		if (fn) {
+			WARN_ON(fwnode->secondary);
+			fwnode->secondary = fn;
+		}
+		dev->fwnode = fwnode;
+	} else {
+		if (fwnode_is_primary(fn)) {
+			dev->fwnode = fn->secondary;
+			if (!(parent && fn == parent->fwnode))
+				fn->secondary = NULL;
+		} else {
+			dev->fwnode = NULL;
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(set_primary_fwnode);
+
+/**
+ * set_secondary_fwnode - Change the secondary firmware node of a given device.
+ * @dev: Device to handle.
+ * @fwnode: New secondary firmware node of the device.
+ *
+ * If a primary firmware node of the device is present, set its secondary
+ * pointer to @fwnode.  Otherwise, set the device's firmware node pointer to
+ * @fwnode.
+ */
+void set_secondary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
+{
+	if (fwnode)
+		fwnode->secondary = ERR_PTR(-ENODEV);
+
+	if (fwnode_is_primary(dev->fwnode))
+		dev->fwnode->secondary = fwnode;
+	else
+		dev->fwnode = fwnode;
+}
+EXPORT_SYMBOL_GPL(set_secondary_fwnode);
+
+/**
+ * device_set_of_node_from_dev - reuse device-tree node of another device
+ * @dev: device whose device-tree node is being set
+ * @dev2: device whose device-tree node is being reused
+ *
+ * Takes another reference to the new device-tree node after first dropping
+ * any reference held to the old node.
+ */
+void device_set_of_node_from_dev(struct device *dev, const struct device *dev2)
+{
+	of_node_put(dev->of_node);
+	dev->of_node = of_node_get(dev2->of_node);
+	dev->of_node_reused = true;
+}
+EXPORT_SYMBOL_GPL(device_set_of_node_from_dev);
+
+void device_set_node(struct device *dev, struct fwnode_handle *fwnode)
+{
+	dev->fwnode = fwnode;
+	dev->of_node = to_of_node(fwnode);
+}
+EXPORT_SYMBOL_GPL(device_set_node);
+
+int device_match_name(struct device *dev, const void *name)
+{
+	return sysfs_streq(dev_name(dev), name);
+}
+EXPORT_SYMBOL_GPL(device_match_name);
+
+int device_match_of_node(struct device *dev, const void *np)
+{
+	return dev->of_node == np;
+}
+EXPORT_SYMBOL_GPL(device_match_of_node);
+
+int device_match_fwnode(struct device *dev, const void *fwnode)
+{
+	return dev_fwnode(dev) == fwnode;
+}
+EXPORT_SYMBOL_GPL(device_match_fwnode);
+
+int device_match_devt(struct device *dev, const void *pdevt)
+{
+	return dev->devt == *(dev_t *)pdevt;
+}
+EXPORT_SYMBOL_GPL(device_match_devt);
+
+int device_match_acpi_dev(struct device *dev, const void *adev)
+{
+	return ACPI_COMPANION(dev) == adev;
+}
+EXPORT_SYMBOL(device_match_acpi_dev);
+
+int device_match_any(struct device *dev, const void *unused)
+{
+	return 1;
+}
+EXPORT_SYMBOL_GPL(device_match_any);