samples/configfs/configfs_sample.c

   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");