Documentation/filesystems/configfs/configfs_example_macros.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)), struct childless, subsys) : NULL;
  58 }
  59
  60 CONFIGFS_ATTR_STRUCT(childless);
  61 #define CHILDLESS_ATTR(_name, _mode, _show, _store)     \
  62 struct childless_attribute childless_attr_##_name = __CONFIGFS_ATTR(_name, _mode, _show, _store)
  63 #define CHILDLESS_ATTR_RO(_name, _show) \
  64 struct childless_attribute childless_attr_##_name = __CONFIGFS_ATTR_RO(_name, _show);
  65
  66 static ssize_t childless_showme_read(struct childless *childless,
  67                                      char *page)
  68 {
  69         ssize_t pos;
  70
  71         pos = sprintf(page, "%d\n", childless->showme);
  72         childless->showme++;
  73
  74         return pos;
  75 }
  76
  77 static ssize_t childless_storeme_read(struct childless *childless,
  78                                       char *page)
  79 {
  80         return sprintf(page, "%d\n", childless->storeme);
  81 }
  82
  83 static ssize_t childless_storeme_write(struct childless *childless,
  84                                        const char *page,
  85                                        size_t count)
  86 {
  87         unsigned long tmp;
  88         char *p = (char *) page;
  89
  90         tmp = simple_strtoul(p, &p, 10);
  91         if (!p || (*p && (*p != '\n')))
  92                 return -EINVAL;
  93
  94         if (tmp > INT_MAX)
  95                 return -ERANGE;
  96
  97         childless->storeme = tmp;
  98
  99         return count;
 100 }
 101
 102 static ssize_t childless_description_read(struct childless *childless,
 103                                           char *page)
 104 {
 105         return sprintf(page,
 106 "[01-childless]\n"
 107 "\n"
 108 "The childless subsystem is the simplest possible subsystem in\n"
 109 "configfs.  It does not support the creation of child config_items.\n"
 110 "It only has a few attributes.  In fact, it isn't much different\n"
 111 "than a directory in /proc.\n");
 112 }
 113
 114 CHILDLESS_ATTR_RO(showme, childless_showme_read);
 115 CHILDLESS_ATTR(storeme, S_IRUGO | S_IWUSR, childless_storeme_read,
 116                childless_storeme_write);
 117 CHILDLESS_ATTR_RO(description, childless_description_read);
 118
 119 static struct configfs_attribute *childless_attrs[] = {
 120         &childless_attr_showme.attr,
 121         &childless_attr_storeme.attr,
 122         &childless_attr_description.attr,
 123         NULL,
 124 };
 125
 126 CONFIGFS_ATTR_OPS(childless);
 127 static struct configfs_item_operations childless_item_ops = {
 128         .show_attribute         = childless_attr_show,
 129         .store_attribute        = childless_attr_store,
 130 };
 131
 132 static struct config_item_type childless_type = {
 133         .ct_item_ops    = &childless_item_ops,
 134         .ct_attrs       = childless_attrs,
 135         .ct_owner       = THIS_MODULE,
 136 };
 137
 138 static struct childless childless_subsys = {
 139         .subsys = {
 140                 .su_group = {
 141                         .cg_item = {
 142                                 .ci_namebuf = "01-childless",
 143                                 .ci_type = &childless_type,
 144                         },
 145                 },
 146         },
 147 };
 148
 149
 150 /* ----------------------------------------------------------------- */
 151
 152 /*
 153  * 02-simple-children
 154  *
 155  * This example merely has a simple one-attribute child.  Note that
 156  * there is no extra attribute structure, as the child's attribute is
 157  * known from the get-go.  Also, there is no container for the
 158  * subsystem, as it has no attributes of its own.
 159  */
 160
 161 struct simple_child {
 162         struct config_item item;
 163         int storeme;
 164 };
 165
 166 static inline struct simple_child *to_simple_child(struct config_item *item)
 167 {
 168         return item ? container_of(item, struct simple_child, item) : NULL;
 169 }
 170
 171 static struct configfs_attribute simple_child_attr_storeme = {
 172         .ca_owner = THIS_MODULE,
 173         .ca_name = "storeme",
 174         .ca_mode = S_IRUGO | S_IWUSR,
 175 };
 176
 177 static struct configfs_attribute *simple_child_attrs[] = {
 178         &simple_child_attr_storeme,
 179         NULL,
 180 };
 181
 182 static ssize_t simple_child_attr_show(struct config_item *item,
 183                                       struct configfs_attribute *attr,
 184                                       char *page)
 185 {
 186         ssize_t count;
 187         struct simple_child *simple_child = to_simple_child(item);
 188
 189         count = sprintf(page, "%d\n", simple_child->storeme);
 190
 191         return count;
 192 }
 193
 194 static ssize_t simple_child_attr_store(struct config_item *item,
 195                                        struct configfs_attribute *attr,
 196                                        const char *page, size_t count)
 197 {
 198         struct simple_child *simple_child = to_simple_child(item);
 199         unsigned long tmp;
 200         char *p = (char *) page;
 201
 202         tmp = simple_strtoul(p, &p, 10);
 203         if (!p || (*p && (*p != '\n')))
 204                 return -EINVAL;
 205
 206         if (tmp > INT_MAX)
 207                 return -ERANGE;
 208
 209         simple_child->storeme = tmp;
 210
 211         return count;
 212 }
 213
 214 static void simple_child_release(struct config_item *item)
 215 {
 216         kfree(to_simple_child(item));
 217 }
 218
 219 static struct configfs_item_operations simple_child_item_ops = {
 220         .release                = simple_child_release,
 221         .show_attribute         = simple_child_attr_show,
 222         .store_attribute        = simple_child_attr_store,
 223 };
 224
 225 static struct config_item_type simple_child_type = {
 226         .ct_item_ops    = &simple_child_item_ops,
 227         .ct_attrs       = simple_child_attrs,
 228         .ct_owner       = THIS_MODULE,
 229 };
 230
 231
 232 struct simple_children {
 233         struct config_group group;
 234 };
 235
 236 static inline struct simple_children *to_simple_children(struct config_item *item)
 237 {
 238         return item ? container_of(to_config_group(item), struct simple_children, group) : NULL;
 239 }
 240
 241 static struct config_item *simple_children_make_item(struct config_group *group, const char *name)
 242 {
 243         struct simple_child *simple_child;
 244
 245         simple_child = kzalloc(sizeof(struct simple_child), GFP_KERNEL);
 246         if (!simple_child)
 247                 return ERR_PTR(-ENOMEM);
 248
 249         config_item_init_type_name(&simple_child->item, name,
 250                                    &simple_child_type);
 251
 252         simple_child->storeme = 0;
 253
 254         return &simple_child->item;
 255 }
 256
 257 static struct configfs_attribute simple_children_attr_description = {
 258         .ca_owner = THIS_MODULE,
 259         .ca_name = "description",
 260         .ca_mode = S_IRUGO,
 261 };
 262
 263 static struct configfs_attribute *simple_children_attrs[] = {
 264         &simple_children_attr_description,
 265         NULL,
 266 };
 267
 268 static ssize_t simple_children_attr_show(struct config_item *item,
 269                                          struct configfs_attribute *attr,
 270                                          char *page)
 271 {
 272         return sprintf(page,
 273 "[02-simple-children]\n"
 274 "\n"
 275 "This subsystem allows the creation of child config_items.  These\n"
 276 "items have only one attribute that is readable and writeable.\n");
 277 }
 278
 279 static void simple_children_release(struct config_item *item)
 280 {
 281         kfree(to_simple_children(item));
 282 }
 283
 284 static struct configfs_item_operations simple_children_item_ops = {
 285         .release        = simple_children_release,
 286         .show_attribute = simple_children_attr_show,
 287 };
 288
 289 /*
 290  * Note that, since no extra work is required on ->drop_item(),
 291  * no ->drop_item() is provided.
 292  */
 293 static struct configfs_group_operations simple_children_group_ops = {
 294         .make_item      = simple_children_make_item,
 295 };
 296
 297 static struct config_item_type simple_children_type = {
 298         .ct_item_ops    = &simple_children_item_ops,
 299         .ct_group_ops   = &simple_children_group_ops,
 300         .ct_attrs       = simple_children_attrs,
 301         .ct_owner       = THIS_MODULE,
 302 };
 303
 304 static struct configfs_subsystem simple_children_subsys = {
 305         .su_group = {
 306                 .cg_item = {
 307                         .ci_namebuf = "02-simple-children",
 308                         .ci_type = &simple_children_type,
 309                 },
 310         },
 311 };
 312
 313
 314 /* ----------------------------------------------------------------- */
 315
 316 /*
 317  * 03-group-children
 318  *
 319  * This example reuses the simple_children group from above.  However,
 320  * the simple_children group is not the subsystem itself, it is a
 321  * child of the subsystem.  Creation of a group in the subsystem creates
 322  * a new simple_children group.  That group can then have simple_child
 323  * children of its own.
 324  */
 325
 326 static struct config_group *group_children_make_group(struct config_group *group, const char *name)
 327 {
 328         struct simple_children *simple_children;
 329
 330         simple_children = kzalloc(sizeof(struct simple_children),
 331                                   GFP_KERNEL);
 332         if (!simple_children)
 333                 return ERR_PTR(-ENOMEM);
 334
 335         config_group_init_type_name(&simple_children->group, name,
 336                                     &simple_children_type);
 337
 338         return &simple_children->group;
 339 }
 340
 341 static struct configfs_attribute group_children_attr_description = {
 342         .ca_owner = THIS_MODULE,
 343         .ca_name = "description",
 344         .ca_mode = S_IRUGO,
 345 };
 346
 347 static struct configfs_attribute *group_children_attrs[] = {
 348         &group_children_attr_description,
 349         NULL,
 350 };
 351
 352 static ssize_t group_children_attr_show(struct config_item *item,
 353                                         struct configfs_attribute *attr,
 354                                         char *page)
 355 {
 356         return sprintf(page,
 357 "[03-group-children]\n"
 358 "\n"
 359 "This subsystem allows the creation of child config_groups.  These\n"
 360 "groups are like the subsystem simple-children.\n");
 361 }
 362
 363 static struct configfs_item_operations group_children_item_ops = {
 364         .show_attribute = group_children_attr_show,
 365 };
 366
 367 /*
 368  * Note that, since no extra work is required on ->drop_item(),
 369  * no ->drop_item() is provided.
 370  */
 371 static struct configfs_group_operations group_children_group_ops = {
 372         .make_group     = group_children_make_group,
 373 };
 374
 375 static struct config_item_type group_children_type = {
 376         .ct_item_ops    = &group_children_item_ops,
 377         .ct_group_ops   = &group_children_group_ops,
 378         .ct_attrs       = group_children_attrs,
 379         .ct_owner       = THIS_MODULE,
 380 };
 381
 382 static struct configfs_subsystem group_children_subsys = {
 383         .su_group = {
 384                 .cg_item = {
 385                         .ci_namebuf = "03-group-children",
 386                         .ci_type = &group_children_type,
 387                 },
 388         },
 389 };
 390
 391 /* ----------------------------------------------------------------- */
 392
 393 /*
 394  * We're now done with our subsystem definitions.
 395  * For convenience in this module, here's a list of them all.  It
 396  * allows the init function to easily register them.  Most modules
 397  * will only have one subsystem, and will only call register_subsystem
 398  * on it directly.
 399  */
 400 static struct configfs_subsystem *example_subsys[] = {
 401         &childless_subsys.subsys,
 402         &simple_children_subsys,
 403         &group_children_subsys,
 404         NULL,
 405 };
 406
 407 static int __init configfs_example_init(void)
 408 {
 409         int ret;
 410         int i;
 411         struct configfs_subsystem *subsys;
 412
 413         for (i = 0; example_subsys[i]; i++) {
 414                 subsys = example_subsys[i];
 415
 416                 config_group_init(&subsys->su_group);
 417                 mutex_init(&subsys->su_mutex);
 418                 ret = configfs_register_subsystem(subsys);
 419                 if (ret) {
 420                         printk(KERN_ERR "Error %d while registering subsystem %s\n",
 421                                ret,
 422                                subsys->su_group.cg_item.ci_namebuf);
 423                         goto out_unregister;
 424                 }
 425         }
 426
 427         return 0;
 428
 429 out_unregister:
 430         for (i--; i >= 0; i--)
 431                 configfs_unregister_subsystem(example_subsys[i]);
 432
 433         return ret;
 434 }
 435
 436 static void __exit configfs_example_exit(void)
 437 {
 438         int i;
 439
 440         for (i = 0; example_subsys[i]; i++)
 441                 configfs_unregister_subsystem(example_subsys[i]);
 442 }
 443
 444 module_init(configfs_example_init);
 445 module_exit(configfs_example_exit);
 446 MODULE_LICENSE("GPL");