1 /*
2  * vim: noexpandtab ts=8 sts=0 sw=8:
3  *
4  * configfs_example_macros.c - This file is a demonstration module
5  *      containing a number of configfs subsystems.  It uses the helper
6  *      macros defined by configfs.h
7  *
8  * This program is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU General Public
10  * License as published by the Free Software Foundation; either
11  * version 2 of the License, or (at your option) any later version.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16  * General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public
19  * License along with this program; if not, write to the
20  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
21  * Boston, MA 021110-1307, USA.
22  *
23  * Based on sysfs:
24  * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
25  *
26  * configfs Copyright (C) 2005 Oracle.  All rights reserved.
27  */
28 
29 #include <linux/init.h>
30 #include <linux/module.h>
31 #include <linux/slab.h>
32 
33 #include <linux/configfs.h>
34 
35 
36 
37 /*
38  * 01-childless
39  *
40  * This first example is a childless subsystem.  It cannot create
41  * any config_items.  It just has attributes.
42  *
43  * Note that we are enclosing the configfs_subsystem inside a container.
44  * This is not necessary if a subsystem has no attributes directly
45  * on the subsystem.  See the next example, 02-simple-children, for
46  * such a subsystem.
47  */
48 
49 struct childless {
50 	struct configfs_subsystem subsys;
51 	int showme;
52 	int storeme;
53 };
54 
55 static inline struct childless *to_childless(struct config_item *item)
56 {
57 	return item ? container_of(to_configfs_subsystem(to_config_group(item)),
58 			struct childless, subsys) : NULL;
59 }
60 
61 static ssize_t childless_showme_show(struct config_item *item, char *page)
62 {
63 	struct childless *childless = to_childless(item);
64 	ssize_t pos;
65 
66 	pos = sprintf(page, "%d\n", childless->showme);
67 	childless->showme++;
68 
69 	return pos;
70 }
71 
72 static ssize_t childless_storeme_show(struct config_item *item, char *page)
73 {
74 	return sprintf(page, "%d\n", to_childless(item)->storeme);
75 }
76 
77 static ssize_t childless_storeme_store(struct config_item *item,
78 		const char *page, size_t count)
79 {
80 	struct childless *childless = to_childless(item);
81 	unsigned long tmp;
82 	char *p = (char *) page;
83 
84 	tmp = simple_strtoul(p, &p, 10);
85 	if (!p || (*p && (*p != '\n')))
86 		return -EINVAL;
87 
88 	if (tmp > INT_MAX)
89 		return -ERANGE;
90 
91 	childless->storeme = tmp;
92 
93 	return count;
94 }
95 
96 static ssize_t childless_description_show(struct config_item *item, char *page)
97 {
98 	return sprintf(page,
99 "[01-childless]\n"
100 "\n"
101 "The childless subsystem is the simplest possible subsystem in\n"
102 "configfs.  It does not support the creation of child config_items.\n"
103 "It only has a few attributes.  In fact, it isn't much different\n"
104 "than a directory in /proc.\n");
105 }
106 
107 CONFIGFS_ATTR_RO(childless_, showme);
108 CONFIGFS_ATTR(childless_, storeme);
109 CONFIGFS_ATTR_RO(childless_, description);
110 
111 static struct configfs_attribute *childless_attrs[] = {
112 	&childless_attr_showme,
113 	&childless_attr_storeme,
114 	&childless_attr_description,
115 	NULL,
116 };
117 
118 static struct config_item_type childless_type = {
119 	.ct_attrs	= childless_attrs,
120 	.ct_owner	= THIS_MODULE,
121 };
122 
123 static struct childless childless_subsys = {
124 	.subsys = {
125 		.su_group = {
126 			.cg_item = {
127 				.ci_namebuf = "01-childless",
128 				.ci_type = &childless_type,
129 			},
130 		},
131 	},
132 };
133 
134 
135 /* ----------------------------------------------------------------- */
136 
137 /*
138  * 02-simple-children
139  *
140  * This example merely has a simple one-attribute child.  Note that
141  * there is no extra attribute structure, as the child's attribute is
142  * known from the get-go.  Also, there is no container for the
143  * subsystem, as it has no attributes of its own.
144  */
145 
146 struct simple_child {
147 	struct config_item item;
148 	int storeme;
149 };
150 
151 static inline struct simple_child *to_simple_child(struct config_item *item)
152 {
153 	return item ? container_of(item, struct simple_child, item) : NULL;
154 }
155 
156 static ssize_t simple_child_storeme_show(struct config_item *item, char *page)
157 {
158 	return sprintf(page, "%d\n", to_simple_child(item)->storeme);
159 }
160 
161 static ssize_t simple_child_storeme_store(struct config_item *item,
162 		const char *page, size_t count)
163 {
164 	struct simple_child *simple_child = to_simple_child(item);
165 	unsigned long tmp;
166 	char *p = (char *) page;
167 
168 	tmp = simple_strtoul(p, &p, 10);
169 	if (!p || (*p && (*p != '\n')))
170 		return -EINVAL;
171 
172 	if (tmp > INT_MAX)
173 		return -ERANGE;
174 
175 	simple_child->storeme = tmp;
176 
177 	return count;
178 }
179 
180 CONFIGFS_ATTR(simple_child_, storeme);
181 
182 static struct configfs_attribute *simple_child_attrs[] = {
183 	&simple_child_attr_storeme,
184 	NULL,
185 };
186 
187 static void simple_child_release(struct config_item *item)
188 {
189 	kfree(to_simple_child(item));
190 }
191 
192 static struct configfs_item_operations simple_child_item_ops = {
193 	.release		= simple_child_release,
194 };
195 
196 static struct config_item_type simple_child_type = {
197 	.ct_item_ops	= &simple_child_item_ops,
198 	.ct_attrs	= simple_child_attrs,
199 	.ct_owner	= THIS_MODULE,
200 };
201 
202 
203 struct simple_children {
204 	struct config_group group;
205 };
206 
207 static inline struct simple_children *to_simple_children(struct config_item *item)
208 {
209 	return item ? container_of(to_config_group(item),
210 			struct simple_children, group) : NULL;
211 }
212 
213 static struct config_item *simple_children_make_item(struct config_group *group,
214 		const char *name)
215 {
216 	struct simple_child *simple_child;
217 
218 	simple_child = kzalloc(sizeof(struct simple_child), GFP_KERNEL);
219 	if (!simple_child)
220 		return ERR_PTR(-ENOMEM);
221 
222 	config_item_init_type_name(&simple_child->item, name,
223 				   &simple_child_type);
224 
225 	simple_child->storeme = 0;
226 
227 	return &simple_child->item;
228 }
229 
230 static ssize_t simple_children_description_show(struct config_item *item,
231 		char *page)
232 {
233 	return sprintf(page,
234 "[02-simple-children]\n"
235 "\n"
236 "This subsystem allows the creation of child config_items.  These\n"
237 "items have only one attribute that is readable and writeable.\n");
238 }
239 
240 CONFIGFS_ATTR_RO(simple_children_, description);
241 
242 static struct configfs_attribute *simple_children_attrs[] = {
243 	&simple_children_attr_description,
244 	NULL,
245 };
246 
247 static void simple_children_release(struct config_item *item)
248 {
249 	kfree(to_simple_children(item));
250 }
251 
252 static struct configfs_item_operations simple_children_item_ops = {
253 	.release	= simple_children_release,
254 };
255 
256 /*
257  * Note that, since no extra work is required on ->drop_item(),
258  * no ->drop_item() is provided.
259  */
260 static struct configfs_group_operations simple_children_group_ops = {
261 	.make_item	= simple_children_make_item,
262 };
263 
264 static struct config_item_type simple_children_type = {
265 	.ct_item_ops	= &simple_children_item_ops,
266 	.ct_group_ops	= &simple_children_group_ops,
267 	.ct_attrs	= simple_children_attrs,
268 	.ct_owner	= THIS_MODULE,
269 };
270 
271 static struct configfs_subsystem simple_children_subsys = {
272 	.su_group = {
273 		.cg_item = {
274 			.ci_namebuf = "02-simple-children",
275 			.ci_type = &simple_children_type,
276 		},
277 	},
278 };
279 
280 
281 /* ----------------------------------------------------------------- */
282 
283 /*
284  * 03-group-children
285  *
286  * This example reuses the simple_children group from above.  However,
287  * the simple_children group is not the subsystem itself, it is a
288  * child of the subsystem.  Creation of a group in the subsystem creates
289  * a new simple_children group.  That group can then have simple_child
290  * children of its own.
291  */
292 
293 static struct config_group *group_children_make_group(
294 		struct config_group *group, const char *name)
295 {
296 	struct simple_children *simple_children;
297 
298 	simple_children = kzalloc(sizeof(struct simple_children),
299 				  GFP_KERNEL);
300 	if (!simple_children)
301 		return ERR_PTR(-ENOMEM);
302 
303 	config_group_init_type_name(&simple_children->group, name,
304 				    &simple_children_type);
305 
306 	return &simple_children->group;
307 }
308 
309 static ssize_t group_children_description_show(struct config_item *item,
310 		char *page)
311 {
312 	return sprintf(page,
313 "[03-group-children]\n"
314 "\n"
315 "This subsystem allows the creation of child config_groups.  These\n"
316 "groups are like the subsystem simple-children.\n");
317 }
318 
319 CONFIGFS_ATTR_RO(group_children_, description);
320 
321 static struct configfs_attribute *group_children_attrs[] = {
322 	&group_children_attr_description,
323 	NULL,
324 };
325 
326 /*
327  * Note that, since no extra work is required on ->drop_item(),
328  * no ->drop_item() is provided.
329  */
330 static struct configfs_group_operations group_children_group_ops = {
331 	.make_group	= group_children_make_group,
332 };
333 
334 static struct config_item_type group_children_type = {
335 	.ct_group_ops	= &group_children_group_ops,
336 	.ct_attrs	= group_children_attrs,
337 	.ct_owner	= THIS_MODULE,
338 };
339 
340 static struct configfs_subsystem group_children_subsys = {
341 	.su_group = {
342 		.cg_item = {
343 			.ci_namebuf = "03-group-children",
344 			.ci_type = &group_children_type,
345 		},
346 	},
347 };
348 
349 /* ----------------------------------------------------------------- */
350 
351 /*
352  * We're now done with our subsystem definitions.
353  * For convenience in this module, here's a list of them all.  It
354  * allows the init function to easily register them.  Most modules
355  * will only have one subsystem, and will only call register_subsystem
356  * on it directly.
357  */
358 static struct configfs_subsystem *example_subsys[] = {
359 	&childless_subsys.subsys,
360 	&simple_children_subsys,
361 	&group_children_subsys,
362 	NULL,
363 };
364 
365 static int __init configfs_example_init(void)
366 {
367 	int ret;
368 	int i;
369 	struct configfs_subsystem *subsys;
370 
371 	for (i = 0; example_subsys[i]; i++) {
372 		subsys = example_subsys[i];
373 
374 		config_group_init(&subsys->su_group);
375 		mutex_init(&subsys->su_mutex);
376 		ret = configfs_register_subsystem(subsys);
377 		if (ret) {
378 			printk(KERN_ERR "Error %d while registering subsystem %s\n",
379 			       ret,
380 			       subsys->su_group.cg_item.ci_namebuf);
381 			goto out_unregister;
382 		}
383 	}
384 
385 	return 0;
386 
387 out_unregister:
388 	for (i--; i >= 0; i--)
389 		configfs_unregister_subsystem(example_subsys[i]);
390 
391 	return ret;
392 }
393 
394 static void __exit configfs_example_exit(void)
395 {
396 	int i;
397 
398 	for (i = 0; example_subsys[i]; i++)
399 		configfs_unregister_subsystem(example_subsys[i]);
400 }
401 
402 module_init(configfs_example_init);
403 module_exit(configfs_example_exit);
404 MODULE_LICENSE("GPL");
405