summaryrefslogtreecommitdiff
path: root/samples/configfs/configfs_sample.c
blob: f9008be7a8a115119920e71df59e94d6149b23e7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * vim: noexpandtab ts=8 sts=0 sw=8:
 *
 * configfs_example_macros.c - This file is a demonstration module
 *      containing a number of configfs subsystems.  It uses the helper
 *      macros defined by configfs.h
 *
 * Based on sysfs:
 *      sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
 *
 * configfs Copyright (C) 2005 Oracle.  All rights reserved.
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/configfs.h>

/*
 * 01-childless
 *
 * This first example is a childless subsystem.  It cannot create
 * any config_items.  It just has attributes.
 *
 * Note that we are enclosing the configfs_subsystem inside a container.
 * This is not necessary if a subsystem has no attributes directly
 * on the subsystem.  See the next example, 02-simple-children, for
 * such a subsystem.
 */

struct childless {
	struct configfs_subsystem subsys;
	int showme;
	int storeme;
};

static inline struct childless *to_childless(struct config_item *item)
{
	return container_of(to_configfs_subsystem(to_config_group(item)),
			    struct childless, subsys);
}

static ssize_t childless_showme_show(struct config_item *item, char *page)
{
	struct childless *childless = to_childless(item);
	ssize_t pos;

	pos = sprintf(page, "%d\n", childless->showme);
	childless->showme++;

	return pos;
}

static ssize_t childless_storeme_show(struct config_item *item, char *page)
{
	return sprintf(page, "%d\n", to_childless(item)->storeme);
}

static ssize_t childless_storeme_store(struct config_item *item,
		const char *page, size_t count)
{
	struct childless *childless = to_childless(item);
	int ret;

	ret = kstrtoint(page, 10, &childless->storeme);
	if (ret)
		return ret;

	return count;
}

static ssize_t childless_description_show(struct config_item *item, char *page)
{
	return sprintf(page,
"[01-childless]\n"
"\n"
"The childless subsystem is the simplest possible subsystem in\n"
"configfs.  It does not support the creation of child config_items.\n"
"It only has a few attributes.  In fact, it isn't much different\n"
"than a directory in /proc.\n");
}

CONFIGFS_ATTR_RO(childless_, showme);
CONFIGFS_ATTR(childless_, storeme);
CONFIGFS_ATTR_RO(childless_, description);

static struct configfs_attribute *childless_attrs[] = {
	&childless_attr_showme,
	&childless_attr_storeme,
	&childless_attr_description,
	NULL,
};

static const struct config_item_type childless_type = {
	.ct_attrs	= childless_attrs,
	.ct_owner	= THIS_MODULE,
};

static struct childless childless_subsys = {
	.subsys = {
		.su_group = {
			.cg_item = {
				.ci_namebuf = "01-childless",
				.ci_type = &childless_type,
			},
		},
	},
};

/* ----------------------------------------------------------------- */

/*
 * 02-simple-children
 *
 * This example merely has a simple one-attribute child.  Note that
 * there is no extra attribute structure, as the child's attribute is
 * known from the get-go.  Also, there is no container for the
 * subsystem, as it has no attributes of its own.
 */

struct simple_child {
	struct config_item item;
	int storeme;
};

static inline struct simple_child *to_simple_child(struct config_item *item)
{
	return container_of(item, struct simple_child, item);
}

static ssize_t simple_child_storeme_show(struct config_item *item, char *page)
{
	return sprintf(page, "%d\n", to_simple_child(item)->storeme);
}

static ssize_t simple_child_storeme_store(struct config_item *item,
		const char *page, size_t count)
{
	struct simple_child *simple_child = to_simple_child(item);
	int ret;

	ret = kstrtoint(page, 10, &simple_child->storeme);
	if (ret)
		return ret;

	return count;
}

CONFIGFS_ATTR(simple_child_, storeme);

static struct configfs_attribute *simple_child_attrs[] = {
	&simple_child_attr_storeme,
	NULL,
};

static void simple_child_release(struct config_item *item)
{
	kfree(to_simple_child(item));
}

static struct configfs_item_operations simple_child_item_ops = {
	.release	= simple_child_release,
};

static const struct config_item_type simple_child_type = {
	.ct_item_ops	= &simple_child_item_ops,
	.ct_attrs	= simple_child_attrs,
	.ct_owner	= THIS_MODULE,
};

struct simple_children {
	struct config_group group;
};

static inline struct simple_children *to_simple_children(struct config_item *item)
{
	return container_of(to_config_group(item),
			    struct simple_children, group);
}

static struct config_item *simple_children_make_item(struct config_group *group,
		const char *name)
{
	struct simple_child *simple_child;

	simple_child = kzalloc(sizeof(struct simple_child), GFP_KERNEL);
	if (!simple_child)
		return ERR_PTR(-ENOMEM);

	config_item_init_type_name(&simple_child->item, name,
				   &simple_child_type);

	return &simple_child->item;
}

static ssize_t simple_children_description_show(struct config_item *item,
		char *page)
{
	return sprintf(page,
"[02-simple-children]\n"
"\n"
"This subsystem allows the creation of child config_items.  These\n"
"items have only one attribute that is readable and writeable.\n");
}

CONFIGFS_ATTR_RO(simple_children_, description);

static struct configfs_attribute *simple_children_attrs[] = {
	&simple_children_attr_description,
	NULL,
};

static void simple_children_release(struct config_item *item)
{
	kfree(to_simple_children(item));
}

static struct configfs_item_operations simple_children_item_ops = {
	.release	= simple_children_release,
};

/*
 * Note that, since no extra work is required on ->drop_item(),
 * no ->drop_item() is provided.
 */
static struct configfs_group_operations simple_children_group_ops = {
	.make_item	= simple_children_make_item,
};

static const struct config_item_type simple_children_type = {
	.ct_item_ops	= &simple_children_item_ops,
	.ct_group_ops	= &simple_children_group_ops,
	.ct_attrs	= simple_children_attrs,
	.ct_owner	= THIS_MODULE,
};

static struct configfs_subsystem simple_children_subsys = {
	.su_group = {
		.cg_item = {
			.ci_namebuf = "02-simple-children",
			.ci_type = &simple_children_type,
		},
	},
};

/* ----------------------------------------------------------------- */

/*
 * 03-group-children
 *
 * This example reuses the simple_children group from above.  However,
 * the simple_children group is not the subsystem itself, it is a
 * child of the subsystem.  Creation of a group in the subsystem creates
 * a new simple_children group.  That group can then have simple_child
 * children of its own.
 */

static struct config_group *group_children_make_group(
		struct config_group *group, const char *name)
{
	struct simple_children *simple_children;

	simple_children = kzalloc(sizeof(struct simple_children),
				  GFP_KERNEL);
	if (!simple_children)
		return ERR_PTR(-ENOMEM);

	config_group_init_type_name(&simple_children->group, name,
				    &simple_children_type);

	return &simple_children->group;
}

static ssize_t group_children_description_show(struct config_item *item,
		char *page)
{
	return sprintf(page,
"[03-group-children]\n"
"\n"
"This subsystem allows the creation of child config_groups.  These\n"
"groups are like the subsystem simple-children.\n");
}

CONFIGFS_ATTR_RO(group_children_, description);

static struct configfs_attribute *group_children_attrs[] = {
	&group_children_attr_description,
	NULL,
};

/*
 * Note that, since no extra work is required on ->drop_item(),
 * no ->drop_item() is provided.
 */
static struct configfs_group_operations group_children_group_ops = {
	.make_group	= group_children_make_group,
};

static const struct config_item_type group_children_type = {
	.ct_group_ops	= &group_children_group_ops,
	.ct_attrs	= group_children_attrs,
	.ct_owner	= THIS_MODULE,
};

static struct configfs_subsystem group_children_subsys = {
	.su_group = {
		.cg_item = {
			.ci_namebuf = "03-group-children",
			.ci_type = &group_children_type,
		},
	},
};

/* ----------------------------------------------------------------- */

/*
 * We're now done with our subsystem definitions.
 * For convenience in this module, here's a list of them all.  It
 * allows the init function to easily register them.  Most modules
 * will only have one subsystem, and will only call register_subsystem
 * on it directly.
 */
static struct configfs_subsystem *example_subsys[] = {
	&childless_subsys.subsys,
	&simple_children_subsys,
	&group_children_subsys,
	NULL,
};

static int __init configfs_example_init(void)
{
	struct configfs_subsystem *subsys;
	int ret, i;

	for (i = 0; example_subsys[i]; i++) {
		subsys = example_subsys[i];

		config_group_init(&subsys->su_group);
		mutex_init(&subsys->su_mutex);
		ret = configfs_register_subsystem(subsys);
		if (ret) {
			pr_err("Error %d while registering subsystem %s\n",
			       ret, subsys->su_group.cg_item.ci_namebuf);
			goto out_unregister;
		}
	}

	return 0;

out_unregister:
	for (i--; i >= 0; i--)
		configfs_unregister_subsystem(example_subsys[i]);

	return ret;
}

static void __exit configfs_example_exit(void)
{
	int i;

	for (i = 0; example_subsys[i]; i++)
		configfs_unregister_subsystem(example_subsys[i]);
}

module_init(configfs_example_init);
module_exit(configfs_example_exit);
MODULE_LICENSE("GPL");