Adding upstream version 5.10.209.upstream/5.10.209upstream

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

1 files changed, 913 insertions, 0 deletions

diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
new file mode 100644
index 000000000..b664c3638
--- /dev/null
+++ b/drivers/base/swnode.c
@@ -0,0 +1,913 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Software nodes for the firmware node framework.
+ *
+ * Copyright (C) 2018, Intel Corporation
+ * Author: Heikki Krogerus <heikki.krogerus@linux.intel.com>
+ */
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+
+struct swnode {
+	int id;
+	struct kobject kobj;
+	struct fwnode_handle fwnode;
+	const struct software_node *node;
+
+	/* hierarchy */
+	struct ida child_ids;
+	struct list_head entry;
+	struct list_head children;
+	struct swnode *parent;
+
+	unsigned int allocated:1;
+};
+
+static DEFINE_IDA(swnode_root_ids);
+static struct kset *swnode_kset;
+
+#define kobj_to_swnode(_kobj_) container_of(_kobj_, struct swnode, kobj)
+
+static const struct fwnode_operations software_node_ops;
+
+bool is_software_node(const struct fwnode_handle *fwnode)
+{
+	return !IS_ERR_OR_NULL(fwnode) && fwnode->ops == &software_node_ops;
+}
+EXPORT_SYMBOL_GPL(is_software_node);
+
+#define to_swnode(__fwnode)						\
+	({								\
+		typeof(__fwnode) __to_swnode_fwnode = __fwnode;		\
+									\
+		is_software_node(__to_swnode_fwnode) ?			\
+			container_of(__to_swnode_fwnode,		\
+				     struct swnode, fwnode) : NULL;	\
+	})
+
+static struct swnode *
+software_node_to_swnode(const struct software_node *node)
+{
+	struct swnode *swnode = NULL;
+	struct kobject *k;
+
+	if (!node)
+		return NULL;
+
+	spin_lock(&swnode_kset->list_lock);
+
+	list_for_each_entry(k, &swnode_kset->list, entry) {
+		swnode = kobj_to_swnode(k);
+		if (swnode->node == node)
+			break;
+		swnode = NULL;
+	}
+
+	spin_unlock(&swnode_kset->list_lock);
+
+	return swnode;
+}
+
+const struct software_node *to_software_node(const struct fwnode_handle *fwnode)
+{
+	const struct swnode *swnode = to_swnode(fwnode);
+
+	return swnode ? swnode->node : NULL;
+}
+EXPORT_SYMBOL_GPL(to_software_node);
+
+struct fwnode_handle *software_node_fwnode(const struct software_node *node)
+{
+	struct swnode *swnode = software_node_to_swnode(node);
+
+	return swnode ? &swnode->fwnode : NULL;
+}
+EXPORT_SYMBOL_GPL(software_node_fwnode);
+
+/* -------------------------------------------------------------------------- */
+/* property_entry processing */
+
+static const struct property_entry *
+property_entry_get(const struct property_entry *prop, const char *name)
+{
+	if (!prop)
+		return NULL;
+
+	for (; prop->name; prop++)
+		if (!strcmp(name, prop->name))
+			return prop;
+
+	return NULL;
+}
+
+static const void *property_get_pointer(const struct property_entry *prop)
+{
+	if (!prop->length)
+		return NULL;
+
+	return prop->is_inline ? &prop->value : prop->pointer;
+}
+
+static const void *property_entry_find(const struct property_entry *props,
+				       const char *propname, size_t length)
+{
+	const struct property_entry *prop;
+	const void *pointer;
+
+	prop = property_entry_get(props, propname);
+	if (!prop)
+		return ERR_PTR(-EINVAL);
+	pointer = property_get_pointer(prop);
+	if (!pointer)
+		return ERR_PTR(-ENODATA);
+	if (length > prop->length)
+		return ERR_PTR(-EOVERFLOW);
+	return pointer;
+}
+
+static int
+property_entry_count_elems_of_size(const struct property_entry *props,
+				   const char *propname, size_t length)
+{
+	const struct property_entry *prop;
+
+	prop = property_entry_get(props, propname);
+	if (!prop)
+		return -EINVAL;
+
+	return prop->length / length;
+}
+
+static int property_entry_read_int_array(const struct property_entry *props,
+					 const char *name,
+					 unsigned int elem_size, void *val,
+					 size_t nval)
+{
+	const void *pointer;
+	size_t length;
+
+	if (!val)
+		return property_entry_count_elems_of_size(props, name,
+							  elem_size);
+
+	if (!is_power_of_2(elem_size) || elem_size > sizeof(u64))
+		return -ENXIO;
+
+	length = nval * elem_size;
+
+	pointer = property_entry_find(props, name, length);
+	if (IS_ERR(pointer))
+		return PTR_ERR(pointer);
+
+	memcpy(val, pointer, length);
+	return 0;
+}
+
+static int property_entry_read_string_array(const struct property_entry *props,
+					    const char *propname,
+					    const char **strings, size_t nval)
+{
+	const void *pointer;
+	size_t length;
+	int array_len;
+
+	/* Find out the array length. */
+	array_len = property_entry_count_elems_of_size(props, propname,
+						       sizeof(const char *));
+	if (array_len < 0)
+		return array_len;
+
+	/* Return how many there are if strings is NULL. */
+	if (!strings)
+		return array_len;
+
+	array_len = min_t(size_t, nval, array_len);
+	length = array_len * sizeof(*strings);
+
+	pointer = property_entry_find(props, propname, length);
+	if (IS_ERR(pointer))
+		return PTR_ERR(pointer);
+
+	memcpy(strings, pointer, length);
+
+	return array_len;
+}
+
+static void property_entry_free_data(const struct property_entry *p)
+{
+	const char * const *src_str;
+	size_t i, nval;
+
+	if (p->type == DEV_PROP_STRING) {
+		src_str = property_get_pointer(p);
+		nval = p->length / sizeof(*src_str);
+		for (i = 0; i < nval; i++)
+			kfree(src_str[i]);
+	}
+
+	if (!p->is_inline)
+		kfree(p->pointer);
+
+	kfree(p->name);
+}
+
+static bool property_copy_string_array(const char **dst_ptr,
+				       const char * const *src_ptr,
+				       size_t nval)
+{
+	int i;
+
+	for (i = 0; i < nval; i++) {
+		dst_ptr[i] = kstrdup(src_ptr[i], GFP_KERNEL);
+		if (!dst_ptr[i] && src_ptr[i]) {
+			while (--i >= 0)
+				kfree(dst_ptr[i]);
+			return false;
+		}
+	}
+
+	return true;
+}
+
+static int property_entry_copy_data(struct property_entry *dst,
+				    const struct property_entry *src)
+{
+	const void *pointer = property_get_pointer(src);
+	void *dst_ptr;
+	size_t nval;
+
+	/*
+	 * Properties with no data should not be marked as stored
+	 * out of line.
+	 */
+	if (!src->is_inline && !src->length)
+		return -ENODATA;
+
+	/*
+	 * Reference properties are never stored inline as
+	 * they are too big.
+	 */
+	if (src->type == DEV_PROP_REF && src->is_inline)
+		return -EINVAL;
+
+	if (src->length <= sizeof(dst->value)) {
+		dst_ptr = &dst->value;
+		dst->is_inline = true;
+	} else {
+		dst_ptr = kmalloc(src->length, GFP_KERNEL);
+		if (!dst_ptr)
+			return -ENOMEM;
+		dst->pointer = dst_ptr;
+	}
+
+	if (src->type == DEV_PROP_STRING) {
+		nval = src->length / sizeof(const char *);
+		if (!property_copy_string_array(dst_ptr, pointer, nval)) {
+			if (!dst->is_inline)
+				kfree(dst->pointer);
+			return -ENOMEM;
+		}
+	} else {
+		memcpy(dst_ptr, pointer, src->length);
+	}
+
+	dst->length = src->length;
+	dst->type = src->type;
+	dst->name = kstrdup(src->name, GFP_KERNEL);
+	if (!dst->name) {
+		property_entry_free_data(dst);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+/**
+ * property_entries_dup - duplicate array of properties
+ * @properties: array of properties to copy
+ *
+ * This function creates a deep copy of the given NULL-terminated array
+ * of property entries.
+ */
+struct property_entry *
+property_entries_dup(const struct property_entry *properties)
+{
+	struct property_entry *p;
+	int i, n = 0;
+	int ret;
+
+	if (!properties)
+		return NULL;
+
+	while (properties[n].name)
+		n++;
+
+	p = kcalloc(n + 1, sizeof(*p), GFP_KERNEL);
+	if (!p)
+		return ERR_PTR(-ENOMEM);
+
+	for (i = 0; i < n; i++) {
+		ret = property_entry_copy_data(&p[i], &properties[i]);
+		if (ret) {
+			while (--i >= 0)
+				property_entry_free_data(&p[i]);
+			kfree(p);
+			return ERR_PTR(ret);
+		}
+	}
+
+	return p;
+}
+EXPORT_SYMBOL_GPL(property_entries_dup);
+
+/**
+ * property_entries_free - free previously allocated array of properties
+ * @properties: array of properties to destroy
+ *
+ * This function frees given NULL-terminated array of property entries,
+ * along with their data.
+ */
+void property_entries_free(const struct property_entry *properties)
+{
+	const struct property_entry *p;
+
+	if (!properties)
+		return;
+
+	for (p = properties; p->name; p++)
+		property_entry_free_data(p);
+
+	kfree(properties);
+}
+EXPORT_SYMBOL_GPL(property_entries_free);
+
+/* -------------------------------------------------------------------------- */
+/* fwnode operations */
+
+static struct fwnode_handle *software_node_get(struct fwnode_handle *fwnode)
+{
+	struct swnode *swnode = to_swnode(fwnode);
+
+	kobject_get(&swnode->kobj);
+
+	return &swnode->fwnode;
+}
+
+static void software_node_put(struct fwnode_handle *fwnode)
+{
+	struct swnode *swnode = to_swnode(fwnode);
+
+	kobject_put(&swnode->kobj);
+}
+
+static bool software_node_property_present(const struct fwnode_handle *fwnode,
+					   const char *propname)
+{
+	struct swnode *swnode = to_swnode(fwnode);
+
+	return !!property_entry_get(swnode->node->properties, propname);
+}
+
+static int software_node_read_int_array(const struct fwnode_handle *fwnode,
+					const char *propname,
+					unsigned int elem_size, void *val,
+					size_t nval)
+{
+	struct swnode *swnode = to_swnode(fwnode);
+
+	return property_entry_read_int_array(swnode->node->properties, propname,
+					     elem_size, val, nval);
+}
+
+static int software_node_read_string_array(const struct fwnode_handle *fwnode,
+					   const char *propname,
+					   const char **val, size_t nval)
+{
+	struct swnode *swnode = to_swnode(fwnode);
+
+	return property_entry_read_string_array(swnode->node->properties,
+						propname, val, nval);
+}
+
+static const char *
+software_node_get_name(const struct fwnode_handle *fwnode)
+{
+	const struct swnode *swnode = to_swnode(fwnode);
+
+	if (!swnode)
+		return "(null)";
+
+	return kobject_name(&swnode->kobj);
+}
+
+static const char *
+software_node_get_name_prefix(const struct fwnode_handle *fwnode)
+{
+	struct fwnode_handle *parent;
+	const char *prefix;
+
+	parent = fwnode_get_parent(fwnode);
+	if (!parent)
+		return "";
+
+	/* Figure out the prefix from the parents. */
+	while (is_software_node(parent))
+		parent = fwnode_get_next_parent(parent);
+
+	prefix = fwnode_get_name_prefix(parent);
+	fwnode_handle_put(parent);
+
+	/* Guess something if prefix was NULL. */
+	return prefix ?: "/";
+}
+
+static struct fwnode_handle *
+software_node_get_parent(const struct fwnode_handle *fwnode)
+{
+	struct swnode *swnode = to_swnode(fwnode);
+
+	if (!swnode || !swnode->parent)
+		return NULL;
+
+	return fwnode_handle_get(&swnode->parent->fwnode);
+}
+
+static struct fwnode_handle *
+software_node_get_next_child(const struct fwnode_handle *fwnode,
+			     struct fwnode_handle *child)
+{
+	struct swnode *p = to_swnode(fwnode);
+	struct swnode *c = to_swnode(child);
+
+	if (!p || list_empty(&p->children) ||
+	    (c && list_is_last(&c->entry, &p->children))) {
+		fwnode_handle_put(child);
+		return NULL;
+	}
+
+	if (c)
+		c = list_next_entry(c, entry);
+	else
+		c = list_first_entry(&p->children, struct swnode, entry);
+
+	fwnode_handle_put(child);
+	return fwnode_handle_get(&c->fwnode);
+}
+
+static struct fwnode_handle *
+software_node_get_named_child_node(const struct fwnode_handle *fwnode,
+				   const char *childname)
+{
+	struct swnode *swnode = to_swnode(fwnode);
+	struct swnode *child;
+
+	if (!swnode || list_empty(&swnode->children))
+		return NULL;
+
+	list_for_each_entry(child, &swnode->children, entry) {
+		if (!strcmp(childname, kobject_name(&child->kobj))) {
+			kobject_get(&child->kobj);
+			return &child->fwnode;
+		}
+	}
+	return NULL;
+}
+
+static int
+software_node_get_reference_args(const struct fwnode_handle *fwnode,
+				 const char *propname, const char *nargs_prop,
+				 unsigned int nargs, unsigned int index,
+				 struct fwnode_reference_args *args)
+{
+	struct swnode *swnode = to_swnode(fwnode);
+	const struct software_node_ref_args *ref_array;
+	const struct software_node_ref_args *ref;
+	const struct property_entry *prop;
+	struct fwnode_handle *refnode;
+	u32 nargs_prop_val;
+	int error;
+	int i;
+
+	if (!swnode)
+		return -ENOENT;
+
+	prop = property_entry_get(swnode->node->properties, propname);
+	if (!prop)
+		return -ENOENT;
+
+	if (prop->type != DEV_PROP_REF)
+		return -EINVAL;
+
+	/*
+	 * We expect that references are never stored inline, even
+	 * single ones, as they are too big.
+	 */
+	if (prop->is_inline)
+		return -EINVAL;
+
+	if (index * sizeof(*ref) >= prop->length)
+		return -ENOENT;
+
+	ref_array = prop->pointer;
+	ref = &ref_array[index];
+
+	refnode = software_node_fwnode(ref->node);
+	if (!refnode)
+		return -ENOENT;
+
+	if (nargs_prop) {
+		error = property_entry_read_int_array(ref->node->properties,
+						      nargs_prop, sizeof(u32),
+						      &nargs_prop_val, 1);
+		if (error)
+			return error;
+
+		nargs = nargs_prop_val;
+	}
+
+	if (nargs > NR_FWNODE_REFERENCE_ARGS)
+		return -EINVAL;
+
+	if (!args)
+		return 0;
+
+	args->fwnode = software_node_get(refnode);
+	args->nargs = nargs;
+
+	for (i = 0; i < nargs; i++)
+		args->args[i] = ref->args[i];
+
+	return 0;
+}
+
+static const struct fwnode_operations software_node_ops = {
+	.get = software_node_get,
+	.put = software_node_put,
+	.property_present = software_node_property_present,
+	.property_read_int_array = software_node_read_int_array,
+	.property_read_string_array = software_node_read_string_array,
+	.get_name = software_node_get_name,
+	.get_name_prefix = software_node_get_name_prefix,
+	.get_parent = software_node_get_parent,
+	.get_next_child_node = software_node_get_next_child,
+	.get_named_child_node = software_node_get_named_child_node,
+	.get_reference_args = software_node_get_reference_args
+};
+
+/* -------------------------------------------------------------------------- */
+
+/**
+ * software_node_find_by_name - Find software node by name
+ * @parent: Parent of the software node
+ * @name: Name of the software node
+ *
+ * The function will find a node that is child of @parent and that is named
+ * @name. If no node is found, the function returns NULL.
+ *
+ * NOTE: you will need to drop the reference with fwnode_handle_put() after use.
+ */
+const struct software_node *
+software_node_find_by_name(const struct software_node *parent, const char *name)
+{
+	struct swnode *swnode = NULL;
+	struct kobject *k;
+
+	if (!name)
+		return NULL;
+
+	spin_lock(&swnode_kset->list_lock);
+
+	list_for_each_entry(k, &swnode_kset->list, entry) {
+		swnode = kobj_to_swnode(k);
+		if (parent == swnode->node->parent && swnode->node->name &&
+		    !strcmp(name, swnode->node->name)) {
+			kobject_get(&swnode->kobj);
+			break;
+		}
+		swnode = NULL;
+	}
+
+	spin_unlock(&swnode_kset->list_lock);
+
+	return swnode ? swnode->node : NULL;
+}
+EXPORT_SYMBOL_GPL(software_node_find_by_name);
+
+static int
+software_node_register_properties(struct software_node *node,
+				  const struct property_entry *properties)
+{
+	struct property_entry *props;
+
+	props = property_entries_dup(properties);
+	if (IS_ERR(props))
+		return PTR_ERR(props);
+
+	node->properties = props;
+
+	return 0;
+}
+
+static void software_node_release(struct kobject *kobj)
+{
+	struct swnode *swnode = kobj_to_swnode(kobj);
+
+	if (swnode->parent) {
+		ida_simple_remove(&swnode->parent->child_ids, swnode->id);
+		list_del(&swnode->entry);
+	} else {
+		ida_simple_remove(&swnode_root_ids, swnode->id);
+	}
+
+	if (swnode->allocated) {
+		property_entries_free(swnode->node->properties);
+		kfree(swnode->node);
+	}
+	ida_destroy(&swnode->child_ids);
+	kfree(swnode);
+}
+
+static struct kobj_type software_node_type = {
+	.release = software_node_release,
+	.sysfs_ops = &kobj_sysfs_ops,
+};
+
+static struct fwnode_handle *
+swnode_register(const struct software_node *node, struct swnode *parent,
+		unsigned int allocated)
+{
+	struct swnode *swnode;
+	int ret;
+
+	swnode = kzalloc(sizeof(*swnode), GFP_KERNEL);
+	if (!swnode) {
+		ret = -ENOMEM;
+		goto out_err;
+	}
+
+	ret = ida_simple_get(parent ? &parent->child_ids : &swnode_root_ids,
+			     0, 0, GFP_KERNEL);
+	if (ret < 0) {
+		kfree(swnode);
+		goto out_err;
+	}
+
+	swnode->id = ret;
+	swnode->node = node;
+	swnode->parent = parent;
+	swnode->allocated = allocated;
+	swnode->kobj.kset = swnode_kset;
+	swnode->fwnode.ops = &software_node_ops;
+
+	ida_init(&swnode->child_ids);
+	INIT_LIST_HEAD(&swnode->entry);
+	INIT_LIST_HEAD(&swnode->children);
+
+	if (node->name)
+		ret = kobject_init_and_add(&swnode->kobj, &software_node_type,
+					   parent ? &parent->kobj : NULL,
+					   "%s", node->name);
+	else
+		ret = kobject_init_and_add(&swnode->kobj, &software_node_type,
+					   parent ? &parent->kobj : NULL,
+					   "node%d", swnode->id);
+	if (ret) {
+		kobject_put(&swnode->kobj);
+		return ERR_PTR(ret);
+	}
+
+	if (parent)
+		list_add_tail(&swnode->entry, &parent->children);
+
+	kobject_uevent(&swnode->kobj, KOBJ_ADD);
+	return &swnode->fwnode;
+
+out_err:
+	if (allocated)
+		property_entries_free(node->properties);
+	return ERR_PTR(ret);
+}
+
+/**
+ * software_node_register_nodes - Register an array of software nodes
+ * @nodes: Zero terminated array of software nodes to be registered
+ *
+ * Register multiple software nodes at once.
+ */
+int software_node_register_nodes(const struct software_node *nodes)
+{
+	int ret;
+	int i;
+
+	for (i = 0; nodes[i].name; i++) {
+		ret = software_node_register(&nodes[i]);
+		if (ret) {
+			software_node_unregister_nodes(nodes);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(software_node_register_nodes);
+
+/**
+ * software_node_unregister_nodes - Unregister an array of software nodes
+ * @nodes: Zero terminated array of software nodes to be unregistered
+ *
+ * Unregister multiple software nodes at once.
+ *
+ * NOTE: Be careful using this call if the nodes had parent pointers set up in
+ * them before registering.  If so, it is wiser to remove the nodes
+ * individually, in the correct order (child before parent) instead of relying
+ * on the sequential order of the list of nodes in the array.
+ */
+void software_node_unregister_nodes(const struct software_node *nodes)
+{
+	int i;
+
+	for (i = 0; nodes[i].name; i++)
+		software_node_unregister(&nodes[i]);
+}
+EXPORT_SYMBOL_GPL(software_node_unregister_nodes);
+
+/**
+ * software_node_register_node_group - Register a group of software nodes
+ * @node_group: NULL terminated array of software node pointers to be registered
+ *
+ * Register multiple software nodes at once.
+ */
+int software_node_register_node_group(const struct software_node **node_group)
+{
+	unsigned int i;
+	int ret;
+
+	if (!node_group)
+		return 0;
+
+	for (i = 0; node_group[i]; i++) {
+		ret = software_node_register(node_group[i]);
+		if (ret) {
+			software_node_unregister_node_group(node_group);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(software_node_register_node_group);
+
+/**
+ * software_node_unregister_node_group - Unregister a group of software nodes
+ * @node_group: NULL terminated array of software node pointers to be unregistered
+ *
+ * Unregister multiple software nodes at once.
+ */
+void software_node_unregister_node_group(const struct software_node **node_group)
+{
+	unsigned int i;
+
+	if (!node_group)
+		return;
+
+	for (i = 0; node_group[i]; i++)
+		software_node_unregister(node_group[i]);
+}
+EXPORT_SYMBOL_GPL(software_node_unregister_node_group);
+
+/**
+ * software_node_register - Register static software node
+ * @node: The software node to be registered
+ */
+int software_node_register(const struct software_node *node)
+{
+	struct swnode *parent = software_node_to_swnode(node->parent);
+
+	if (software_node_to_swnode(node))
+		return -EEXIST;
+
+	if (node->parent && !parent)
+		return -EINVAL;
+
+	return PTR_ERR_OR_ZERO(swnode_register(node, parent, 0));
+}
+EXPORT_SYMBOL_GPL(software_node_register);
+
+/**
+ * software_node_unregister - Unregister static software node
+ * @node: The software node to be unregistered
+ */
+void software_node_unregister(const struct software_node *node)
+{
+	struct swnode *swnode;
+
+	swnode = software_node_to_swnode(node);
+	if (swnode)
+		fwnode_remove_software_node(&swnode->fwnode);
+}
+EXPORT_SYMBOL_GPL(software_node_unregister);
+
+struct fwnode_handle *
+fwnode_create_software_node(const struct property_entry *properties,
+			    const struct fwnode_handle *parent)
+{
+	struct software_node *node;
+	struct swnode *p = NULL;
+	int ret;
+
+	if (parent) {
+		if (IS_ERR(parent))
+			return ERR_CAST(parent);
+		if (!is_software_node(parent))
+			return ERR_PTR(-EINVAL);
+		p = to_swnode(parent);
+	}
+
+	node = kzalloc(sizeof(*node), GFP_KERNEL);
+	if (!node)
+		return ERR_PTR(-ENOMEM);
+
+	ret = software_node_register_properties(node, properties);
+	if (ret) {
+		kfree(node);
+		return ERR_PTR(ret);
+	}
+
+	node->parent = p ? p->node : NULL;
+
+	return swnode_register(node, p, 1);
+}
+EXPORT_SYMBOL_GPL(fwnode_create_software_node);
+
+void fwnode_remove_software_node(struct fwnode_handle *fwnode)
+{
+	struct swnode *swnode = to_swnode(fwnode);
+
+	if (!swnode)
+		return;
+
+	kobject_put(&swnode->kobj);
+}
+EXPORT_SYMBOL_GPL(fwnode_remove_software_node);
+
+int software_node_notify(struct device *dev, unsigned long action)
+{
+	struct fwnode_handle *fwnode = dev_fwnode(dev);
+	struct swnode *swnode;
+	int ret;
+
+	if (!fwnode)
+		return 0;
+
+	if (!is_software_node(fwnode))
+		fwnode = fwnode->secondary;
+	if (!is_software_node(fwnode))
+		return 0;
+
+	swnode = to_swnode(fwnode);
+
+	switch (action) {
+	case KOBJ_ADD:
+		ret = sysfs_create_link(&dev->kobj, &swnode->kobj,
+					"software_node");
+		if (ret)
+			break;
+
+		ret = sysfs_create_link(&swnode->kobj, &dev->kobj,
+					dev_name(dev));
+		if (ret) {
+			sysfs_remove_link(&dev->kobj, "software_node");
+			break;
+		}
+		kobject_get(&swnode->kobj);
+		break;
+	case KOBJ_REMOVE:
+		sysfs_remove_link(&swnode->kobj, dev_name(dev));
+		sysfs_remove_link(&dev->kobj, "software_node");
+		kobject_put(&swnode->kobj);
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static int __init software_node_init(void)
+{
+	swnode_kset = kset_create_and_add("software_nodes", NULL, kernel_kobj);
+	if (!swnode_kset)
+		return -ENOMEM;
+	return 0;
+}
+postcore_initcall(software_node_init);
+
+static void __exit software_node_exit(void)
+{
+	ida_destroy(&swnode_root_ids);
+	kset_unregister(swnode_kset);
+}
+__exitcall(software_node_exit);