1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * configfs_example_macros.c - This file is a demonstration module
4 * containing a number of configfs subsystems. It uses the helper
5 * macros defined by configfs.h
8 * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
10 * configfs Copyright (C) 2005 Oracle. All rights reserved.
13 #include <linux/init.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/slab.h>
17 #include <linux/configfs.h>
22 * This first example is a childless subsystem. It cannot create
23 * any config_items. It just has attributes.
25 * Note that we are enclosing the configfs_subsystem inside a container.
26 * This is not necessary if a subsystem has no attributes directly
27 * on the subsystem. See the next example, 02-simple-children, for
32 struct configfs_subsystem subsys;
37 static inline struct childless *to_childless(struct config_item *item)
39 return container_of(to_configfs_subsystem(to_config_group(item)),
40 struct childless, subsys);
43 static ssize_t childless_showme_show(struct config_item *item, char *page)
45 struct childless *childless = to_childless(item);
48 pos = sprintf(page, "%d\n", childless->showme);
54 static ssize_t childless_storeme_show(struct config_item *item, char *page)
56 return sprintf(page, "%d\n", to_childless(item)->storeme);
59 static ssize_t childless_storeme_store(struct config_item *item,
60 const char *page, size_t count)
62 struct childless *childless = to_childless(item);
65 ret = kstrtoint(page, 10, &childless->storeme);
72 static ssize_t childless_description_show(struct config_item *item, char *page)
77 "The childless subsystem is the simplest possible subsystem in\n"
78 "configfs. It does not support the creation of child config_items.\n"
79 "It only has a few attributes. In fact, it isn't much different\n"
80 "than a directory in /proc.\n");
83 CONFIGFS_ATTR_RO(childless_, showme);
84 CONFIGFS_ATTR(childless_, storeme);
85 CONFIGFS_ATTR_RO(childless_, description);
87 static struct configfs_attribute *childless_attrs[] = {
88 &childless_attr_showme,
89 &childless_attr_storeme,
90 &childless_attr_description,
94 static const struct config_item_type childless_type = {
95 .ct_attrs = childless_attrs,
96 .ct_owner = THIS_MODULE,
99 static struct childless childless_subsys = {
103 .ci_namebuf = "01-childless",
104 .ci_type = &childless_type,
110 /* ----------------------------------------------------------------- */
115 * This example merely has a simple one-attribute child. Note that
116 * there is no extra attribute structure, as the child's attribute is
117 * known from the get-go. Also, there is no container for the
118 * subsystem, as it has no attributes of its own.
121 struct simple_child {
122 struct config_item item;
126 static inline struct simple_child *to_simple_child(struct config_item *item)
128 return container_of(item, struct simple_child, item);
131 static ssize_t simple_child_storeme_show(struct config_item *item, char *page)
133 return sprintf(page, "%d\n", to_simple_child(item)->storeme);
136 static ssize_t simple_child_storeme_store(struct config_item *item,
137 const char *page, size_t count)
139 struct simple_child *simple_child = to_simple_child(item);
142 ret = kstrtoint(page, 10, &simple_child->storeme);
149 CONFIGFS_ATTR(simple_child_, storeme);
151 static struct configfs_attribute *simple_child_attrs[] = {
152 &simple_child_attr_storeme,
156 static void simple_child_release(struct config_item *item)
158 kfree(to_simple_child(item));
161 static struct configfs_item_operations simple_child_item_ops = {
162 .release = simple_child_release,
165 static const struct config_item_type simple_child_type = {
166 .ct_item_ops = &simple_child_item_ops,
167 .ct_attrs = simple_child_attrs,
168 .ct_owner = THIS_MODULE,
171 struct simple_children {
172 struct config_group group;
175 static inline struct simple_children *to_simple_children(struct config_item *item)
177 return container_of(to_config_group(item),
178 struct simple_children, group);
181 static struct config_item *simple_children_make_item(struct config_group *group,
184 struct simple_child *simple_child;
186 simple_child = kzalloc(sizeof(struct simple_child), GFP_KERNEL);
188 return ERR_PTR(-ENOMEM);
190 config_item_init_type_name(&simple_child->item, name,
193 return &simple_child->item;
196 static ssize_t simple_children_description_show(struct config_item *item,
200 "[02-simple-children]\n"
202 "This subsystem allows the creation of child config_items. These\n"
203 "items have only one attribute that is readable and writeable.\n");
206 CONFIGFS_ATTR_RO(simple_children_, description);
208 static struct configfs_attribute *simple_children_attrs[] = {
209 &simple_children_attr_description,
213 static void simple_children_release(struct config_item *item)
215 kfree(to_simple_children(item));
218 static struct configfs_item_operations simple_children_item_ops = {
219 .release = simple_children_release,
223 * Note that, since no extra work is required on ->drop_item(),
224 * no ->drop_item() is provided.
226 static struct configfs_group_operations simple_children_group_ops = {
227 .make_item = simple_children_make_item,
230 static const struct config_item_type simple_children_type = {
231 .ct_item_ops = &simple_children_item_ops,
232 .ct_group_ops = &simple_children_group_ops,
233 .ct_attrs = simple_children_attrs,
234 .ct_owner = THIS_MODULE,
237 static struct configfs_subsystem simple_children_subsys = {
240 .ci_namebuf = "02-simple-children",
241 .ci_type = &simple_children_type,
246 /* ----------------------------------------------------------------- */
251 * This example reuses the simple_children group from above. However,
252 * the simple_children group is not the subsystem itself, it is a
253 * child of the subsystem. Creation of a group in the subsystem creates
254 * a new simple_children group. That group can then have simple_child
255 * children of its own.
258 static struct config_group *group_children_make_group(
259 struct config_group *group, const char *name)
261 struct simple_children *simple_children;
263 simple_children = kzalloc(sizeof(struct simple_children),
265 if (!simple_children)
266 return ERR_PTR(-ENOMEM);
268 config_group_init_type_name(&simple_children->group, name,
269 &simple_children_type);
271 return &simple_children->group;
274 static ssize_t group_children_description_show(struct config_item *item,
278 "[03-group-children]\n"
280 "This subsystem allows the creation of child config_groups. These\n"
281 "groups are like the subsystem simple-children.\n");
284 CONFIGFS_ATTR_RO(group_children_, description);
286 static struct configfs_attribute *group_children_attrs[] = {
287 &group_children_attr_description,
292 * Note that, since no extra work is required on ->drop_item(),
293 * no ->drop_item() is provided.
295 static struct configfs_group_operations group_children_group_ops = {
296 .make_group = group_children_make_group,
299 static const struct config_item_type group_children_type = {
300 .ct_group_ops = &group_children_group_ops,
301 .ct_attrs = group_children_attrs,
302 .ct_owner = THIS_MODULE,
305 static struct configfs_subsystem group_children_subsys = {
308 .ci_namebuf = "03-group-children",
309 .ci_type = &group_children_type,
314 /* ----------------------------------------------------------------- */
317 * We're now done with our subsystem definitions.
318 * For convenience in this module, here's a list of them all. It
319 * allows the init function to easily register them. Most modules
320 * will only have one subsystem, and will only call register_subsystem
323 static struct configfs_subsystem *example_subsys[] = {
324 &childless_subsys.subsys,
325 &simple_children_subsys,
326 &group_children_subsys,
330 static int __init configfs_example_init(void)
332 struct configfs_subsystem *subsys;
335 for (i = 0; example_subsys[i]; i++) {
336 subsys = example_subsys[i];
338 config_group_init(&subsys->su_group);
339 mutex_init(&subsys->su_mutex);
340 ret = configfs_register_subsystem(subsys);
342 pr_err("Error %d while registering subsystem %s\n",
343 ret, subsys->su_group.cg_item.ci_namebuf);
351 for (i--; i >= 0; i--)
352 configfs_unregister_subsystem(example_subsys[i]);
357 static void __exit configfs_example_exit(void)
361 for (i = 0; example_subsys[i]; i++)
362 configfs_unregister_subsystem(example_subsys[i]);
365 module_init(configfs_example_init);
366 module_exit(configfs_example_exit);
367 MODULE_LICENSE("GPL");