text: // 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 {
  	struct kobject kobj;
  	struct fwnode_handle fwnode;
  	const struct software_node *node;
  	int id;
  
  	/* hierarchy */
  	struct ida child_ids;
  	struct list_head entry;
  	struct list_head children;
  	struct swnode *parent;
  
  	unsigned int allocated:1;
  	unsigned int managed: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 inline struct swnode *dev_to_swnode(struct device *dev)
  {
  	struct fwnode_handle *fwnode = dev_fwnode(dev);
  
  	if (!fwnode)
  		return NULL;
  
  	if (!is_software_node(fwnode))
  		fwnode = fwnode->secondary;
  
  	return to_swnode(fwnode);
  }
  
  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(swnode->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;
  
  	args->fwnode = software_node_get(refnode);
  	args->nargs = nargs;
  
  	for (i = 0; i < nargs; i++)
  		args->args[i] = ref->args[i];
  
  	return 0;
  }
  
  static struct fwnode_handle *
  swnode_graph_find_next_port(const struct fwnode_handle *parent,
  			    struct fwnode_handle *port)
  {
  	struct fwnode_handle *old = port;
  
  	while ((port = software_node_get_next_child(parent, old))) {
  		/*
  		 * fwnode ports have naming style "port@", so we search for any
  		 * children that follow that convention.
  		 */
  		if (!strncmp(to_swnode(port)->node->name, "port@",
  			     strlen("port@")))
  			return port;
  		old = port;
  	}
  
  	return NULL;
  }
  
  static struct fwnode_handle *
  software_node_graph_get_next_endpoint(const struct fwnode_handle *fwnode,
  				      struct fwnode_handle *endpoint)
  {
  	struct swnode *swnode = to_swnode(fwnode);
  	struct fwnode_handle *parent;
  	struct fwnode_handle *port;
  
  	if (!swnode)
  		return NULL;
  
  	if (endpoint) {
  		port = software_node_get_parent(endpoint);
  		parent = software_node_get_parent(port);
  	} else {
  		parent = software_node_get_named_child_node(fwnode, "ports");
  		if (!parent)
  			parent = software_node_get(&swnode->fwnode);
  
  		port = swnode_graph_find_next_port(parent, NULL);
  	}
  
  	for (; port; port = swnode_graph_find_next_port(parent, port)) {
  		endpoint = software_node_get_next_child(port, endpoint);
  		if (endpoint) {
  			fwnode_handle_put(port);
  			break;
  		}
  	}
  
  	fwnode_handle_put(parent);
  
  	return endpoint;
  }
  
  static struct fwnode_handle *
  software_node_graph_get_remote_endpoint(const struct fwnode_handle *fwnode)
  {
  	struct swnode *swnode = to_swnode(fwnode);
  	const struct software_node_ref_args *ref;
  	const struct property_entry *prop;
  
  	if (!swnode)
  		return NULL;
  
  	prop = property_entry_get(swnode->node->properties, "remote-endpoint");
  	if (!prop || prop->type != DEV_PROP_REF || prop->is_inline)
  		return NULL;
  
  	ref = prop->pointer;
  
  	return software_node_get(software_node_fwnode(ref[0].node));
  }
  
  static struct fwnode_handle *
  software_node_graph_get_port_parent(struct fwnode_handle *fwnode)
  {
  	struct swnode *swnode = to_swnode(fwnode);
  
  	swnode = swnode->parent;
  	if (swnode && !strcmp(swnode->node->name, "ports"))
  		swnode = swnode->parent;
  
  	return swnode ? software_node_get(&swnode->fwnode) : NULL;
  }
  
  static int
  software_node_graph_parse_endpoint(const struct fwnode_handle *fwnode,
  				   struct fwnode_endpoint *endpoint)
  {
  	struct swnode *swnode = to_swnode(fwnode);
  	const char *parent_name = swnode->parent->node->name;
  	int ret;
  
  	if (strlen("port@") >= strlen(parent_name) ||
  	    strncmp(parent_name, "port@", strlen("port@")))
  		return -EINVAL;
  
  	/* Ports have naming style "port@n", we need to select the n */
  	ret = kstrtou32(parent_name + strlen("port@"), 10, &endpoint->port);
  	if (ret)
  		return ret;
  
  	endpoint->id = swnode->id;
  	endpoint->local_fwnode = fwnode;
  
  	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,
  	.graph_get_next_endpoint = software_node_graph_get_next_endpoint,
  	.graph_get_remote_endpoint = software_node_graph_get_remote_endpoint,
  	.graph_get_port_parent = software_node_graph_get_port_parent,
  	.graph_parse_endpoint = software_node_graph_parse_endpoint,
  };
  
  /* -------------------------------------------------------------------------- */
  
  /**
   * 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 struct software_node *software_node_alloc(const struct property_entry *properties)
  {
  	struct property_entry *props;
  	struct software_node *node;
  
  	props = property_entries_dup(properties);
  	if (IS_ERR(props))
  		return ERR_CAST(props);
  
  	node = kzalloc(sizeof(*node), GFP_KERNEL);
  	if (!node) {
  		property_entries_free(props);
  		return ERR_PTR(-ENOMEM);
  	}
  
  	node->properties = props;
  
  	return node;
  }
  
  static void software_node_free(const struct software_node *node)
  {
  	property_entries_free(node->properties);
  	kfree(node);
  }
  
  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)
  		software_node_free(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)
  		return ERR_PTR(-ENOMEM);
  
  	ret = ida_simple_get(parent ? &parent->child_ids : &swnode_root_ids,
  			     0, 0, GFP_KERNEL);
  	if (ret < 0) {
  		kfree(swnode);
  		return ERR_PTR(ret);
  	}
  
  	swnode->id = ret;
  	swnode->node = node;
  	swnode->parent = parent;
  	swnode->kobj.kset = swnode_kset;
  	fwnode_init(&swnode->fwnode, &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);
  	}
  
  	/*
  	 * Assign the flag only in the successful case, so
  	 * the above kobject_put() won't mess up with properties.
  	 */
  	swnode->allocated = allocated;
  
  	if (parent)
  		list_add_tail(&swnode->entry, &parent->children);
  
  	kobject_uevent(&swnode->kobj, KOBJ_ADD);
  	return &swnode->fwnode;
  }
  
  /**
   * 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. If any node in the array
   * has its .parent pointer set (which can only be to another software_node),
   * then its parent **must** have been registered before it is; either outside
   * of this function or by ordering the array such that parent comes before
   * child.
   */
  int software_node_register_nodes(const struct software_node *nodes)
  {
  	int ret;
  	int i;
  
  	for (i = 0; nodes[i].name; i++) {
  		const struct software_node *parent = nodes[i].parent;
  
  		if (parent && !software_node_to_swnode(parent)) {
  			ret = -EINVAL;
  			goto err_unregister_nodes;
  		}
  
  		ret = software_node_register(&nodes[i]);
  		if (ret)
  			goto err_unregister_nodes;
  	}
  
  	return 0;
  
  err_unregister_nodes:
  	software_node_unregister_nodes(nodes);
  	return ret;
  }
  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. If parent pointers are set up
   * in any of the software nodes then the array **must** be ordered such that
   * parents come before their children.
   *
   * NOTE: If you are uncertain whether the array is ordered such that
   * parents will be unregistered before their children, it is wiser to
   * remove the nodes individually, in the correct order (child before
   * parent).
   */
  void software_node_unregister_nodes(const struct software_node *nodes)
  {
  	unsigned int i = 0;
  
  	while (nodes[i].name)
  		i++;
  
  	while (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. If any node in the array
   * has its .parent pointer set (which can only be to another software_node),
   * then its parent **must** have been registered before it is; either outside
   * of this function or by ordering the array such that parent comes before
   * child.
   */
  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. If parent pointers are set up
   * in any of the software nodes then the array **must** be ordered such that
   * parents come before their children.
   *
   * NOTE: If you are uncertain whether the array is ordered such that
   * parents will be unregistered before their children, it is wiser to
   * remove the nodes individually, in the correct order (child before
   * parent).
   */
  void software_node_unregister_node_group(
  		const struct software_node **node_group)
  {
  	unsigned int i = 0;
  
  	if (!node_group)
  		return;
  
  	while (node_group[i])
  		i++;
  
  	while (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 fwnode_handle *fwnode;
  	struct software_node *node;
  	struct swnode *p;
  
  	if (IS_ERR(parent))
  		return ERR_CAST(parent);
  
  	p = to_swnode(parent);
  	if (parent && !p)
  		return ERR_PTR(-EINVAL);
  
  	node = software_node_alloc(properties);
  	if (IS_ERR(node))
  		return ERR_CAST(node);
  
  	node->parent = p ? p->node : NULL;
  
  	fwnode = swnode_register(node, p, 1);
  	if (IS_ERR(fwnode))
  		software_node_free(node);
  
  	return fwnode;
  }
  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);
  
  /**
   * device_add_software_node - Assign software node to a device
   * @dev: The device the software node is meant for.
   * @node: The software node.
   *
   * This function will make @node the secondary firmware node pointer of @dev. If
   * @dev has no primary node, then @node will become the primary node. The
   * function will register @node automatically if it wasn't already registered.
   */
  int device_add_software_node(struct device *dev, const struct software_node *node)
  {
  	struct swnode *swnode;
  	int ret;
  
  	/* Only one software node per device. */
  	if (dev_to_swnode(dev))
  		return -EBUSY;
  
  	swnode = software_node_to_swnode(node);
  	if (swnode) {
  		kobject_get(&swnode->kobj);
  	} else {
  		ret = software_node_register(node);
  		if (ret)
  			return ret;
  
  		swnode = software_node_to_swnode(node);
  	}
  
  	set_secondary_fwnode(dev, &swnode->fwnode);
  
  	/*
  	 * If the device has been fully registered by the time this function is
  	 * called, software_node_notify() must be called separately so that the
  	 * symlinks get created and the reference count of the node is kept in
  	 * balance.
  	 */
  	if (device_is_registered(dev))
  		software_node_notify(dev, KOBJ_ADD);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(device_add_software_node);
  
  /**
   * device_remove_software_node - Remove device's software node
   * @dev: The device with the software node.
   *
   * This function will unregister the software node of @dev.
   */
  void device_remove_software_node(struct device *dev)
  {
  	struct swnode *swnode;
  
  	swnode = dev_to_swnode(dev);
  	if (!swnode)
  		return;
  
  	if (device_is_registered(dev))
  		software_node_notify(dev, KOBJ_REMOVE);
  	set_secondary_fwnode(dev, NULL);
  	kobject_put(&swnode->kobj);
  }
  EXPORT_SYMBOL_GPL(device_remove_software_node);
  
  /**
   * device_create_managed_software_node - Create a software node for a device
   * @dev: The device the software node is assigned to.
   * @properties: Device properties for the software node.
   * @parent: Parent of the software node.
   *
   * Creates a software node as a managed resource for @dev, which means the
   * lifetime of the newly created software node is tied to the lifetime of @dev.
   * Software nodes created with this function should not be reused or shared
   * because of that. The function takes a deep copy of @properties for the
   * software node.
   *
   * Since the new software node is assigned directly to @dev, and since it should
   * not be shared, it is not returned to the caller. The function returns 0 on
   * success, and errno in case of an error.
   */
  int device_create_managed_software_node(struct device *dev,
  					const struct property_entry *properties,
  					const struct software_node *parent)
  {
  	struct fwnode_handle *p = software_node_fwnode(parent);
  	struct fwnode_handle *fwnode;
  
  	if (parent && !p)
  		return -EINVAL;
  
  	fwnode = fwnode_create_software_node(properties, p);
  	if (IS_ERR(fwnode))
  		return PTR_ERR(fwnode);
  
  	to_swnode(fwnode)->managed = true;
  	set_secondary_fwnode(dev, fwnode);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(device_create_managed_software_node);
  
  int software_node_notify(struct device *dev, unsigned long action)
  {
  	struct swnode *swnode;
  	int ret;
  
  	swnode = dev_to_swnode(dev);
  	if (!swnode)
  		return 0;
  
  	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);
  
  		if (swnode->managed) {
  			set_secondary_fwnode(dev, NULL);
  			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);
  