Documentation/filesystems/configfs/configfs_example_explicit.c

   1 /*
   2  * vim: noexpandtab ts=8 sts=0 sw=8:
   3  *
   4  * configfs_example_explicit.c - This file is a demonstration module
   5  *      containing a number of configfs subsystems.  It explicitly defines
   6  *      each structure without using the helper macros defined in
   7  *      configfs.h.
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2 of the License, or (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public
  20  * License along with this program; if not, write to the
  21  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  22  * Boston, MA 021110-1307, USA.
  23  *
  24  * Based on sysfs:
  25  *      sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
  26  *
  27  * configfs Copyright (C) 2005 Oracle.  All rights reserved.
  28  */
  29
  30 #include <linux/init.h>
  31 #include <linux/module.h>
  32 #include <linux/slab.h>
  33
  34 #include <linux/configfs.h>
  35
  36
  37
  38 /*
  39  * 01-childless
  40  *
  41  * This first example is a childless subsystem.  It cannot create
  42  * any config_items.  It just has attributes.
  43  *
  44  * Note that we are enclosing the configfs_subsystem inside a container.
  45  * This is not necessary if a subsystem has no attributes directly
  46  * on the subsystem.  See the next example, 02-simple-children, for
  47  * such a subsystem.
  48  */
  49
  50 struct childless {
  51         struct configfs_subsystem subsys;
  52         int showme;
  53         int storeme;
  54 };
  55
  56 struct childless_attribute {
  57         struct configfs_attribute attr;
  58         ssize_t (*show)(struct childless *, char *);
  59         ssize_t (*store)(struct childless *, const char *, size_t);
  60 };
  61
  62 static inline struct childless *to_childless(struct config_item *item)
  63 {
  64         return item ? container_of(to_configfs_subsystem(to_config_group(item)), struct childless, subsys) : NULL;
  65 }
  66
  67 static ssize_t childless_showme_read(struct childless *childless,
  68                                      char *page)
  69 {
  70         ssize_t pos;
  71
  72         pos = sprintf(page, "%d\n", childless->showme);
  73         childless->showme++;
  74
  75         return pos;
  76 }
  77
  78 static ssize_t childless_storeme_read(struct childless *childless,
  79                                       char *page)
  80 {
  81         return sprintf(page, "%d\n", childless->storeme);
  82 }
  83
  84 static ssize_t childless_storeme_write(struct childless *childless,
  85                                        const char *page,
  86                                        size_t count)
  87 {
  88         unsigned long tmp;
  89         char *p = (char *) page;
  90
  91         tmp = simple_strtoul(p, &p, 10);
  92         if (!p || (*p && (*p != '\n')))
  93                 return -EINVAL;
  94
  95         if (tmp > INT_MAX)
  96                 return -ERANGE;
  97
  98         childless->storeme = tmp;
  99
 100         return count;
 101 }
 102
 103 static ssize_t childless_description_read(struct childless *childless,
 104                                           char *page)
 105 {
 106         return sprintf(page,
 107 "[01-childless]\n"
 108 "\n"
 109 "The childless subsystem is the simplest possible subsystem in\n"
 110 "configfs.  It does not support the creation of child config_items.\n"
 111 "It only has a few attributes.  In fact, it isn't much different\n"
 112 "than a directory in /proc.\n");
 113 }
 114
 115 static struct childless_attribute childless_attr_showme = {
 116         .attr   = { .ca_owner = THIS_MODULE, .ca_name = "showme", .ca_mode = S_IRUGO },
 117         .show   = childless_showme_read,
 118 };
 119 static struct childless_attribute childless_attr_storeme = {
 120         .attr   = { .ca_owner = THIS_MODULE, .ca_name = "storeme", .ca_mode = S_IRUGO | S_IWUSR },
 121         .show   = childless_storeme_read,
 122         .store  = childless_storeme_write,
 123 };
 124 static struct childless_attribute childless_attr_description = {
 125         .attr = { .ca_owner = THIS_MODULE, .ca_name = "description", .ca_mode = S_IRUGO },
 126         .show = childless_description_read,
 127 };
 128
 129 static struct configfs_attribute *childless_attrs[] = {
 130         &childless_attr_showme.attr,
 131         &childless_attr_storeme.attr,
 132         &childless_attr_description.attr,
 133         NULL,
 134 };
 135
 136 static ssize_t childless_attr_show(struct config_item *item,
 137                                    struct configfs_attribute *attr,
 138                                    char *page)
 139 {
 140         struct childless *childless = to_childless(item);
 141         struct childless_attribute *childless_attr =
 142                 container_of(attr, struct childless_attribute, attr);
 143         ssize_t ret = 0;
 144
 145         if (childless_attr->show)
 146                 ret = childless_attr->show(childless, page);
 147         return ret;
 148 }
 149
 150 static ssize_t childless_attr_store(struct config_item *item,
 151                                     struct configfs_attribute *attr,
 152                                     const char *page, size_t count)
 153 {
 154         struct childless *childless = to_childless(item);
 155         struct childless_attribute *childless_attr =
 156                 container_of(attr, struct childless_attribute, attr);
 157         ssize_t ret = -EINVAL;
 158
 159         if (childless_attr->store)
 160                 ret = childless_attr->store(childless, page, count);
 161         return ret;
 162 }
 163
 164 static struct configfs_item_operations childless_item_ops = {
 165         .show_attribute         = childless_attr_show,
 166         .store_attribute        = childless_attr_store,
 167 };
 168
 169 static struct config_item_type childless_type = {
 170         .ct_item_ops    = &childless_item_ops,
 171         .ct_attrs       = childless_attrs,
 172         .ct_owner       = THIS_MODULE,
 173 };
 174
 175 static struct childless childless_subsys = {
 176         .subsys = {
 177                 .su_group = {
 178                         .cg_item = {
 179                                 .ci_namebuf = "01-childless",
 180                                 .ci_type = &childless_type,
 181                         },
 182                 },
 183         },
 184 };
 185
 186
 187 /* ----------------------------------------------------------------- */
 188
 189 /*
 190  * 02-simple-children
 191  *
 192  * This example merely has a simple one-attribute child.  Note that
 193  * there is no extra attribute structure, as the child's attribute is
 194  * known from the get-go.  Also, there is no container for the
 195  * subsystem, as it has no attributes of its own.
 196  */
 197
 198 struct simple_child {
 199         struct config_item item;
 200         int storeme;
 201 };
 202
 203 static inline struct simple_child *to_simple_child(struct config_item *item)
 204 {
 205         return item ? container_of(item, struct simple_child, item) : NULL;
 206 }
 207
 208 static struct configfs_attribute simple_child_attr_storeme = {
 209         .ca_owner = THIS_MODULE,
 210         .ca_name = "storeme",
 211         .ca_mode = S_IRUGO | S_IWUSR,
 212 };
 213
 214 static struct configfs_attribute *simple_child_attrs[] = {
 215         &simple_child_attr_storeme,
 216         NULL,
 217 };
 218
 219 static ssize_t simple_child_attr_show(struct config_item *item,
 220                                       struct configfs_attribute *attr,
 221                                       char *page)
 222 {
 223         ssize_t count;
 224         struct simple_child *simple_child = to_simple_child(item);
 225
 226         count = sprintf(page, "%d\n", simple_child->storeme);
 227
 228         return count;
 229 }
 230
 231 static ssize_t simple_child_attr_store(struct config_item *item,
 232                                        struct configfs_attribute *attr,
 233                                        const char *page, size_t count)
 234 {
 235         struct simple_child *simple_child = to_simple_child(item);
 236         unsigned long tmp;
 237         char *p = (char *) page;
 238
 239         tmp = simple_strtoul(p, &p, 10);
 240         if (!p || (*p && (*p != '\n')))
 241                 return -EINVAL;
 242
 243         if (tmp > INT_MAX)
 244                 return -ERANGE;
 245
 246         simple_child->storeme = tmp;
 247
 248         return count;
 249 }
 250
 251 static void simple_child_release(struct config_item *item)
 252 {
 253         kfree(to_simple_child(item));
 254 }
 255
 256 static struct configfs_item_operations simple_child_item_ops = {
 257         .release                = simple_child_release,
 258         .show_attribute         = simple_child_attr_show,
 259         .store_attribute        = simple_child_attr_store,
 260 };
 261
 262 static struct config_item_type simple_child_type = {
 263         .ct_item_ops    = &simple_child_item_ops,
 264         .ct_attrs       = simple_child_attrs,
 265         .ct_owner       = THIS_MODULE,
 266 };
 267
 268
 269 struct simple_children {
 270         struct config_group group;
 271 };
 272
 273 static inline struct simple_children *to_simple_children(struct config_item *item)
 274 {
 275         return item ? container_of(to_config_group(item), struct simple_children, group) : NULL;
 276 }
 277
 278 static struct config_item *simple_children_make_item(struct config_group *group, const char *name)
 279 {
 280         struct simple_child *simple_child;
 281
 282         simple_child = kzalloc(sizeof(struct simple_child), GFP_KERNEL);
 283         if (!simple_child)
 284                 return ERR_PTR(-ENOMEM);
 285
 286         config_item_init_type_name(&simple_child->item, name,
 287                                    &simple_child_type);
 288
 289         simple_child->storeme = 0;
 290
 291         return &simple_child->item;
 292 }
 293
 294 static struct configfs_attribute simple_children_attr_description = {
 295         .ca_owner = THIS_MODULE,
 296         .ca_name = "description",
 297         .ca_mode = S_IRUGO,
 298 };
 299
 300 static struct configfs_attribute *simple_children_attrs[] = {
 301         &simple_children_attr_description,
 302         NULL,
 303 };
 304
 305 static ssize_t simple_children_attr_show(struct config_item *item,
 306                                          struct configfs_attribute *attr,
 307                                          char *page)
 308 {
 309         return sprintf(page,
 310 "[02-simple-children]\n"
 311 "\n"
 312 "This subsystem allows the creation of child config_items.  These\n"
 313 "items have only one attribute that is readable and writeable.\n");
 314 }
 315
 316 static void simple_children_release(struct config_item *item)
 317 {
 318         kfree(to_simple_children(item));
 319 }
 320
 321 static struct configfs_item_operations simple_children_item_ops = {
 322         .release        = simple_children_release,
 323         .show_attribute = simple_children_attr_show,
 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 simple_children_group_ops = {
 331         .make_item      = simple_children_make_item,
 332 };
 333
 334 static struct config_item_type simple_children_type = {
 335         .ct_item_ops    = &simple_children_item_ops,
 336         .ct_group_ops   = &simple_children_group_ops,
 337         .ct_attrs       = simple_children_attrs,
 338         .ct_owner       = THIS_MODULE,
 339 };
 340
 341 static struct configfs_subsystem simple_children_subsys = {
 342         .su_group = {
 343                 .cg_item = {
 344                         .ci_namebuf = "02-simple-children",
 345                         .ci_type = &simple_children_type,
 346                 },
 347         },
 348 };
 349
 350
 351 /* ----------------------------------------------------------------- */
 352
 353 /*
 354  * 03-group-children
 355  *
 356  * This example reuses the simple_children group from above.  However,
 357  * the simple_children group is not the subsystem itself, it is a
 358  * child of the subsystem.  Creation of a group in the subsystem creates
 359  * a new simple_children group.  That group can then have simple_child
 360  * children of its own.
 361  */
 362
 363 static struct config_group *group_children_make_group(struct config_group *group, const char *name)
 364 {
 365         struct simple_children *simple_children;
 366
 367         simple_children = kzalloc(sizeof(struct simple_children),
 368                                   GFP_KERNEL);
 369         if (!simple_children)
 370                 return ERR_PTR(-ENOMEM);
 371
 372         config_group_init_type_name(&simple_children->group, name,
 373                                     &simple_children_type);
 374
 375         return &simple_children->group;
 376 }
 377
 378 static struct configfs_attribute group_children_attr_description = {
 379         .ca_owner = THIS_MODULE,
 380         .ca_name = "description",
 381         .ca_mode = S_IRUGO,
 382 };
 383
 384 static struct configfs_attribute *group_children_attrs[] = {
 385         &group_children_attr_description,
 386         NULL,
 387 };
 388
 389 static ssize_t group_children_attr_show(struct config_item *item,
 390                                         struct configfs_attribute *attr,
 391                                         char *page)
 392 {
 393         return sprintf(page,
 394 "[03-group-children]\n"
 395 "\n"
 396 "This subsystem allows the creation of child config_groups.  These\n"
 397 "groups are like the subsystem simple-children.\n");
 398 }
 399
 400 static struct configfs_item_operations group_children_item_ops = {
 401         .show_attribute = group_children_attr_show,
 402 };
 403
 404 /*
 405  * Note that, since no extra work is required on ->drop_item(),
 406  * no ->drop_item() is provided.
 407  */
 408 static struct configfs_group_operations group_children_group_ops = {
 409         .make_group     = group_children_make_group,
 410 };
 411
 412 static struct config_item_type group_children_type = {
 413         .ct_item_ops    = &group_children_item_ops,
 414         .ct_group_ops   = &group_children_group_ops,
 415         .ct_attrs       = group_children_attrs,
 416         .ct_owner       = THIS_MODULE,
 417 };
 418
 419 static struct configfs_subsystem group_children_subsys = {
 420         .su_group = {
 421                 .cg_item = {
 422                         .ci_namebuf = "03-group-children",
 423                         .ci_type = &group_children_type,
 424                 },
 425         },
 426 };
 427
 428 /* ----------------------------------------------------------------- */
 429
 430 /*
 431  * We're now done with our subsystem definitions.
 432  * For convenience in this module, here's a list of them all.  It
 433  * allows the init function to easily register them.  Most modules
 434  * will only have one subsystem, and will only call register_subsystem
 435  * on it directly.
 436  */
 437 static struct configfs_subsystem *example_subsys[] = {
 438         &childless_subsys.subsys,
 439         &simple_children_subsys,
 440         &group_children_subsys,
 441         NULL,
 442 };
 443
 444 static int __init configfs_example_init(void)
 445 {
 446         int ret;
 447         int i;
 448         struct configfs_subsystem *subsys;
 449
 450         for (i = 0; example_subsys[i]; i++) {
 451                 subsys = example_subsys[i];
 452
 453                 config_group_init(&subsys->su_group);
 454                 mutex_init(&subsys->su_mutex);
 455                 ret = configfs_register_subsystem(subsys);
 456                 if (ret) {
 457                         printk(KERN_ERR "Error %d while registering subsystem %s\n",
 458                                ret,
 459                                subsys->su_group.cg_item.ci_namebuf);
 460                         goto out_unregister;
 461                 }
 462         }
 463
 464         return 0;
 465
 466 out_unregister:
 467         for (; i >= 0; i--) {
 468                 configfs_unregister_subsystem(example_subsys[i]);
 469         }
 470
 471         return ret;
 472 }
 473
 474 static void __exit configfs_example_exit(void)
 475 {
 476         int i;
 477
 478         for (i = 0; example_subsys[i]; i++) {
 479                 configfs_unregister_subsystem(example_subsys[i]);
 480         }
 481 }
 482
 483 module_init(configfs_example_init);
 484 module_exit(configfs_example_exit);
 485 MODULE_LICENSE("GPL");