1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
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
6 *
7 * Based on sysfs:
8 * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
9 *
10 * configfs Copyright (C) 2005 Oracle. All rights reserved.
11 */
12
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>
18
19 /*
20 * 01-childless
21 *
22 * This first example is a childless subsystem. It cannot create
23 * any config_items. It just has attributes.
24 *
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
28 * such a subsystem.
29 */
30
31 struct childless {
32 struct configfs_subsystem subsys;
33 int showme;
34 int storeme;
35 };
36
37 static inline struct childless *to_childless(struct config_item *item)
38 {
39 return container_of(to_configfs_subsystem(to_config_group(item)),
40 struct childless, subsys);
41 }
42
43 static ssize_t childless_showme_show(struct config_item *item, char *page)
44 {
45 struct childless *childless = to_childless(item);
46 ssize_t pos;
47
48 pos = sprintf(page, "%d\n", childless->showme);
49 childless->showme++;
50
51 return pos;
52 }
53
54 static ssize_t childless_storeme_show(struct config_item *item, char *page)
55 {
56 return sprintf(page, "%d\n", to_childless(item)->storeme);
57 }
58
59 static ssize_t childless_storeme_store(struct config_item *item,
60 const char *page, size_t count)
61 {
62 struct childless *childless = to_childless(item);
63 int ret;
64
65 ret = kstrtoint(page, 10, &childless->storeme);
66 if (ret)
67 return ret;
68
69 return count;
70 }
71
72 static ssize_t childless_description_show(struct config_item *item, char *page)
73 {
74 return sprintf(page,
75 "[01-childless]\n"
76 "\n"
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");
81 }
82
83 CONFIGFS_ATTR_RO(childless_, showme);
84 CONFIGFS_ATTR(childless_, storeme);
85 CONFIGFS_ATTR_RO(childless_, description);
86
87 static struct configfs_attribute *childless_attrs[] = {
88 &childless_attr_showme,
89 &childless_attr_storeme,
90 &childless_attr_description,
91 NULL,
92 };
93
94 static const struct config_item_type childless_type = {
95 .ct_attrs = childless_attrs,
96 .ct_owner = THIS_MODULE,
97 };
98
99 static struct childless childless_subsys = {
100 .subsys = {
101 .su_group = {
102 .cg_item = {
103 .ci_namebuf = "01-childless",
104 .ci_type = &childless_type,
105 },
106 },
107 },
108 };
109
110 /* ----------------------------------------------------------------- */
111
112 /*
113 * 02-simple-children
114 *
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.
119 */
120
121 struct simple_child {
122 struct config_item item;
123 int storeme;
124 };
125
126 static inline struct simple_child *to_simple_child(struct config_item *item)
127 {
128 return container_of(item, struct simple_child, item);
129 }
130
131 static ssize_t simple_child_storeme_show(struct config_item *item, char *page)
132 {
133 return sprintf(page, "%d\n", to_simple_child(item)->storeme);
134 }
135
136 static ssize_t simple_child_storeme_store(struct config_item *item,
137 const char *page, size_t count)
138 {
139 struct simple_child *simple_child = to_simple_child(item);
140 int ret;
141
142 ret = kstrtoint(page, 10, &simple_child->storeme);
143 if (ret)
144 return ret;
145
146 return count;
147 }
148
149 CONFIGFS_ATTR(simple_child_, storeme);
150
151 static struct configfs_attribute *simple_child_attrs[] = {
152 &simple_child_attr_storeme,
153 NULL,
154 };
155
156 static void simple_child_release(struct config_item *item)
157 {
158 kfree(to_simple_child(item));
159 }
160
161 static struct configfs_item_operations simple_child_item_ops = {
162 .release = simple_child_release,
163 };
164
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,
169 };
170
171 struct simple_children {
172 struct config_group group;
173 };
174
175 static inline struct simple_children *to_simple_children(struct config_item *item)
176 {
177 return container_of(to_config_group(item),
178 struct simple_children, group);
179 }
180
181 static struct config_item *simple_children_make_item(struct config_group *group,
182 const char *name)
183 {
184 struct simple_child *simple_child;
185
186 simple_child = kzalloc(sizeof(struct simple_child), GFP_KERNEL);
187 if (!simple_child)
188 return ERR_PTR(-ENOMEM);
189
190 config_item_init_type_name(&simple_child->item, name,
191 &simple_child_type);
192
193 return &simple_child->item;
194 }
195
196 static ssize_t simple_children_description_show(struct config_item *item,
197 char *page)
198 {
199 return sprintf(page,
200 "[02-simple-children]\n"
201 "\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");
204 }
205
206 CONFIGFS_ATTR_RO(simple_children_, description);
207
208 static struct configfs_attribute *simple_children_attrs[] = {
209 &simple_children_attr_description,
210 NULL,
211 };
212
213 static void simple_children_release(struct config_item *item)
214 {
215 kfree(to_simple_children(item));
216 }
217
218 static struct configfs_item_operations simple_children_item_ops = {
219 .release = simple_children_release,
220 };
221
222 /*
223 * Note that, since no extra work is required on ->drop_item(),
224 * no ->drop_item() is provided.
225 */
226 static struct configfs_group_operations simple_children_group_ops = {
227 .make_item = simple_children_make_item,
228 };
229
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,
235 };
236
237 static struct configfs_subsystem simple_children_subsys = {
238 .su_group = {
239 .cg_item = {
240 .ci_namebuf = "02-simple-children",
241 .ci_type = &simple_children_type,
242 },
243 },
244 };
245
246 /* ----------------------------------------------------------------- */
247
248 /*
249 * 03-group-children
250 *
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.
256 */
257
258 static struct config_group *group_children_make_group(
259 struct config_group *group, const char *name)
260 {
261 struct simple_children *simple_children;
262
263 simple_children = kzalloc(sizeof(struct simple_children),
264 GFP_KERNEL);
265 if (!simple_children)
266 return ERR_PTR(-ENOMEM);
267
268 config_group_init_type_name(&simple_children->group, name,
269 &simple_children_type);
270
271 return &simple_children->group;
272 }
273
274 static ssize_t group_children_description_show(struct config_item *item,
275 char *page)
276 {
277 return sprintf(page,
278 "[03-group-children]\n"
279 "\n"
280 "This subsystem allows the creation of child config_groups. These\n"
281 "groups are like the subsystem simple-children.\n");
282 }
283
284 CONFIGFS_ATTR_RO(group_children_, description);
285
286 static struct configfs_attribute *group_children_attrs[] = {
287 &group_children_attr_description,
288 NULL,
289 };
290
291 /*
292 * Note that, since no extra work is required on ->drop_item(),
293 * no ->drop_item() is provided.
294 */
295 static struct configfs_group_operations group_children_group_ops = {
296 .make_group = group_children_make_group,
297 };
298
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,
303 };
304
305 static struct configfs_subsystem group_children_subsys = {
306 .su_group = {
307 .cg_item = {
308 .ci_namebuf = "03-group-children",
309 .ci_type = &group_children_type,
310 },
311 },
312 };
313
314 /* ----------------------------------------------------------------- */
315
316 /*
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
321 * on it directly.
322 */
323 static struct configfs_subsystem *example_subsys[] = {
324 &childless_subsys.subsys,
325 &simple_children_subsys,
326 &group_children_subsys,
327 NULL,
328 };
329
330 static int __init configfs_example_init(void)
331 {
332 struct configfs_subsystem *subsys;
333 int ret, i;
334
335 for (i = 0; example_subsys[i]; i++) {
336 subsys = example_subsys[i];
337
338 config_group_init(&subsys->su_group);
339 mutex_init(&subsys->su_mutex);
340 ret = configfs_register_subsystem(subsys);
341 if (ret) {
342 pr_err("Error %d while registering subsystem %s\n",
343 ret, subsys->su_group.cg_item.ci_namebuf);
344 goto out_unregister;
345 }
346 }
347
348 return 0;
349
350 out_unregister:
351 for (i--; i >= 0; i--)
352 configfs_unregister_subsystem(example_subsys[i]);
353
354 return ret;
355 }
356
357 static void __exit configfs_example_exit(void)
358 {
359 int i;
360
361 for (i = 0; example_subsys[i]; i++)
362 configfs_unregister_subsystem(example_subsys[i]);
363 }
364
365 module_init(configfs_example_init);
366 module_exit(configfs_example_exit);
367 MODULE_DESCRIPTION("Sample configfs module");
368 MODULE_LICENSE("GPL");
369
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