1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * configfs_example_macros.c - This file is a demonstration module 4 * containing a number of configfs subsystems. It uses the helper 5 * macros defined by configfs.h 6 * 7 * Based on sysfs: 8 * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel 9 * 10 * configfs Copyright (C) 2005 Oracle. All rights reserved. 11 */ 12 13 #include <linux/init.h> 14 #include <linux/kernel.h> 15 #include <linux/module.h> 16 #include <linux/slab.h> 17 #include <linux/configfs.h> 18 19 /* 20 * 01-childless 21 * 22 * This first example is a childless subsystem. It cannot create 23 * any config_items. It just has attributes. 24 * 25 * Note that we are enclosing the configfs_subsystem inside a container. 26 * This is not necessary if a subsystem has no attributes directly 27 * on the subsystem. See the next example, 02-simple-children, for 28 * such a subsystem. 29 */ 30 31 struct childless { 32 struct configfs_subsystem subsys; 33 int showme; 34 int storeme; 35 }; 36 37 static inline struct childless *to_childless(struct config_item *item) 38 { 39 return container_of(to_configfs_subsystem(to_config_group(item)), 40 struct childless, subsys); 41 } 42 43 static ssize_t childless_showme_show(struct config_item *item, char *page) 44 { 45 struct childless *childless = to_childless(item); 46 ssize_t pos; 47 48 pos = sprintf(page, "%d\n", childless->showme); 49 childless->showme++; 50 51 return pos; 52 } 53 54 static ssize_t childless_storeme_show(struct config_item *item, char *page) 55 { 56 return sprintf(page, "%d\n", to_childless(item)->storeme); 57 } 58 59 static ssize_t childless_storeme_store(struct config_item *item, 60 const char *page, size_t count) 61 { 62 struct childless *childless = to_childless(item); 63 int ret; 64 65 ret = kstrtoint(page, 10, &childless->storeme); 66 if (ret) 67 return ret; 68 69 return count; 70 } 71 72 static ssize_t childless_description_show(struct config_item *item, char *page) 73 { 74 return sprintf(page, 75 "[01-childless]\n" 76 "\n" 77 "The childless subsystem is the simplest possible subsystem in\n" 78 "configfs. It does not support the creation of child config_items.\n" 79 "It only has a few attributes. In fact, it isn't much different\n" 80 "than a directory in /proc.\n"); 81 } 82 83 CONFIGFS_ATTR_RO(childless_, showme); 84 CONFIGFS_ATTR(childless_, storeme); 85 CONFIGFS_ATTR_RO(childless_, description); 86 87 static struct configfs_attribute *childless_attrs[] = { 88 &childless_attr_showme, 89 &childless_attr_storeme, 90 &childless_attr_description, 91 NULL, 92 }; 93 94 static const struct config_item_type childless_type = { 95 .ct_attrs = childless_attrs, 96 .ct_owner = THIS_MODULE, 97 }; 98 99 static struct childless childless_subsys = { 100 .subsys = { 101 .su_group = { 102 .cg_item = { 103 .ci_namebuf = "01-childless", 104 .ci_type = &childless_type, 105 }, 106 }, 107 }, 108 }; 109 110 /* ----------------------------------------------------------------- */ 111 112 /* 113 * 02-simple-children 114 * 115 * This example merely has a simple one-attribute child. Note that 116 * there is no extra attribute structure, as the child's attribute is 117 * known from the get-go. Also, there is no container for the 118 * subsystem, as it has no attributes of its own. 119 */ 120 121 struct simple_child { 122 struct config_item item; 123 int storeme; 124 }; 125 126 static inline struct simple_child *to_simple_child(struct config_item *item) 127 { 128 return container_of(item, struct simple_child, item); 129 } 130 131 static ssize_t simple_child_storeme_show(struct config_item *item, char *page) 132 { 133 return sprintf(page, "%d\n", to_simple_child(item)->storeme); 134 } 135 136 static ssize_t simple_child_storeme_store(struct config_item *item, 137 const char *page, size_t count) 138 { 139 struct simple_child *simple_child = to_simple_child(item); 140 int ret; 141 142 ret = kstrtoint(page, 10, &simple_child->storeme); 143 if (ret) 144 return ret; 145 146 return count; 147 } 148 149 CONFIGFS_ATTR(simple_child_, storeme); 150 151 static struct configfs_attribute *simple_child_attrs[] = { 152 &simple_child_attr_storeme, 153 NULL, 154 }; 155 156 static void simple_child_release(struct config_item *item) 157 { 158 kfree(to_simple_child(item)); 159 } 160 161 static struct configfs_item_operations simple_child_item_ops = { 162 .release = simple_child_release, 163 }; 164 165 static const struct config_item_type simple_child_type = { 166 .ct_item_ops = &simple_child_item_ops, 167 .ct_attrs = simple_child_attrs, 168 .ct_owner = THIS_MODULE, 169 }; 170 171 struct simple_children { 172 struct config_group group; 173 }; 174 175 static inline struct simple_children *to_simple_children(struct config_item *item) 176 { 177 return container_of(to_config_group(item), 178 struct simple_children, group); 179 } 180 181 static struct config_item *simple_children_make_item(struct config_group *group, 182 const char *name) 183 { 184 struct simple_child *simple_child; 185 186 simple_child = kzalloc(sizeof(struct simple_child), GFP_KERNEL); 187 if (!simple_child) 188 return ERR_PTR(-ENOMEM); 189 190 config_item_init_type_name(&simple_child->item, name, 191 &simple_child_type); 192 193 return &simple_child->item; 194 } 195 196 static ssize_t simple_children_description_show(struct config_item *item, 197 char *page) 198 { 199 return sprintf(page, 200 "[02-simple-children]\n" 201 "\n" 202 "This subsystem allows the creation of child config_items. These\n" 203 "items have only one attribute that is readable and writeable.\n"); 204 } 205 206 CONFIGFS_ATTR_RO(simple_children_, description); 207 208 static struct configfs_attribute *simple_children_attrs[] = { 209 &simple_children_attr_description, 210 NULL, 211 }; 212 213 static void simple_children_release(struct config_item *item) 214 { 215 kfree(to_simple_children(item)); 216 } 217 218 static struct configfs_item_operations simple_children_item_ops = { 219 .release = simple_children_release, 220 }; 221 222 /* 223 * Note that, since no extra work is required on ->drop_item(), 224 * no ->drop_item() is provided. 225 */ 226 static struct configfs_group_operations simple_children_group_ops = { 227 .make_item = simple_children_make_item, 228 }; 229 230 static const struct config_item_type simple_children_type = { 231 .ct_item_ops = &simple_children_item_ops, 232 .ct_group_ops = &simple_children_group_ops, 233 .ct_attrs = simple_children_attrs, 234 .ct_owner = THIS_MODULE, 235 }; 236 237 static struct configfs_subsystem simple_children_subsys = { 238 .su_group = { 239 .cg_item = { 240 .ci_namebuf = "02-simple-children", 241 .ci_type = &simple_children_type, 242 }, 243 }, 244 }; 245 246 /* ----------------------------------------------------------------- */ 247 248 /* 249 * 03-group-children 250 * 251 * This example reuses the simple_children group from above. However, 252 * the simple_children group is not the subsystem itself, it is a 253 * child of the subsystem. Creation of a group in the subsystem creates 254 * a new simple_children group. That group can then have simple_child 255 * children of its own. 256 */ 257 258 static struct config_group *group_children_make_group( 259 struct config_group *group, const char *name) 260 { 261 struct simple_children *simple_children; 262 263 simple_children = kzalloc(sizeof(struct simple_children), 264 GFP_KERNEL); 265 if (!simple_children) 266 return ERR_PTR(-ENOMEM); 267 268 config_group_init_type_name(&simple_children->group, name, 269 &simple_children_type); 270 271 return &simple_children->group; 272 } 273 274 static ssize_t group_children_description_show(struct config_item *item, 275 char *page) 276 { 277 return sprintf(page, 278 "[03-group-children]\n" 279 "\n" 280 "This subsystem allows the creation of child config_groups. These\n" 281 "groups are like the subsystem simple-children.\n"); 282 } 283 284 CONFIGFS_ATTR_RO(group_children_, description); 285 286 static struct configfs_attribute *group_children_attrs[] = { 287 &group_children_attr_description, 288 NULL, 289 }; 290 291 /* 292 * Note that, since no extra work is required on ->drop_item(), 293 * no ->drop_item() is provided. 294 */ 295 static struct configfs_group_operations group_children_group_ops = { 296 .make_group = group_children_make_group, 297 }; 298 299 static const struct config_item_type group_children_type = { 300 .ct_group_ops = &group_children_group_ops, 301 .ct_attrs = group_children_attrs, 302 .ct_owner = THIS_MODULE, 303 }; 304 305 static struct configfs_subsystem group_children_subsys = { 306 .su_group = { 307 .cg_item = { 308 .ci_namebuf = "03-group-children", 309 .ci_type = &group_children_type, 310 }, 311 }, 312 }; 313 314 /* ----------------------------------------------------------------- */ 315 316 /* 317 * We're now done with our subsystem definitions. 318 * For convenience in this module, here's a list of them all. It 319 * allows the init function to easily register them. Most modules 320 * will only have one subsystem, and will only call register_subsystem 321 * on it directly. 322 */ 323 static struct configfs_subsystem *example_subsys[] = { 324 &childless_subsys.subsys, 325 &simple_children_subsys, 326 &group_children_subsys, 327 NULL, 328 }; 329 330 static int __init configfs_example_init(void) 331 { 332 struct configfs_subsystem *subsys; 333 int ret, i; 334 335 for (i = 0; example_subsys[i]; i++) { 336 subsys = example_subsys[i]; 337 338 config_group_init(&subsys->su_group); 339 mutex_init(&subsys->su_mutex); 340 ret = configfs_register_subsystem(subsys); 341 if (ret) { 342 pr_err("Error %d while registering subsystem %s\n", 343 ret, subsys->su_group.cg_item.ci_namebuf); 344 goto out_unregister; 345 } 346 } 347 348 return 0; 349 350 out_unregister: 351 for (i--; i >= 0; i--) 352 configfs_unregister_subsystem(example_subsys[i]); 353 354 return ret; 355 } 356 357 static void __exit configfs_example_exit(void) 358 { 359 int i; 360 361 for (i = 0; example_subsys[i]; i++) 362 configfs_unregister_subsystem(example_subsys[i]); 363 } 364 365 module_init(configfs_example_init); 366 module_exit(configfs_example_exit); 367 MODULE_LICENSE("GPL"); 368