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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * configfs_example_macros.c - This file is a demonstration module4 * containing a number of configfs subsystems. It uses the helper5 * macros defined by configfs.h6 *7 * Based on sysfs:8 * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel9 *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-childless21 *22 * This first example is a childless subsystem. It cannot create23 * 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 directly27 * on the subsystem. See the next example, 02-simple-children, for28 * such a subsystem.29 */30 31struct childless {32 struct configfs_subsystem subsys;33 int showme;34 int storeme;35};36 37static 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 43static 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 54static ssize_t childless_storeme_show(struct config_item *item, char *page)55{56 return sprintf(page, "%d\n", to_childless(item)->storeme);57}58 59static 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 72static 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 83CONFIGFS_ATTR_RO(childless_, showme);84CONFIGFS_ATTR(childless_, storeme);85CONFIGFS_ATTR_RO(childless_, description);86 87static struct configfs_attribute *childless_attrs[] = {88 &childless_attr_showme,89 &childless_attr_storeme,90 &childless_attr_description,91 NULL,92};93 94static const struct config_item_type childless_type = {95 .ct_attrs = childless_attrs,96 .ct_owner = THIS_MODULE,97};98 99static 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-children114 *115 * This example merely has a simple one-attribute child. Note that116 * there is no extra attribute structure, as the child's attribute is117 * known from the get-go. Also, there is no container for the118 * subsystem, as it has no attributes of its own.119 */120 121struct simple_child {122 struct config_item item;123 int storeme;124};125 126static inline struct simple_child *to_simple_child(struct config_item *item)127{128 return container_of(item, struct simple_child, item);129}130 131static 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 136static 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 149CONFIGFS_ATTR(simple_child_, storeme);150 151static struct configfs_attribute *simple_child_attrs[] = {152 &simple_child_attr_storeme,153 NULL,154};155 156static void simple_child_release(struct config_item *item)157{158 kfree(to_simple_child(item));159}160 161static struct configfs_item_operations simple_child_item_ops = {162 .release = simple_child_release,163};164 165static 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 171struct simple_children {172 struct config_group group;173};174 175static 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 181static 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 196static 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 206CONFIGFS_ATTR_RO(simple_children_, description);207 208static struct configfs_attribute *simple_children_attrs[] = {209 &simple_children_attr_description,210 NULL,211};212 213static void simple_children_release(struct config_item *item)214{215 kfree(to_simple_children(item));216}217 218static 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 */226static struct configfs_group_operations simple_children_group_ops = {227 .make_item = simple_children_make_item,228};229 230static 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 237static 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-children250 *251 * This example reuses the simple_children group from above. However,252 * the simple_children group is not the subsystem itself, it is a253 * child of the subsystem. Creation of a group in the subsystem creates254 * a new simple_children group. That group can then have simple_child255 * children of its own.256 */257 258static 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 274static 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 284CONFIGFS_ATTR_RO(group_children_, description);285 286static 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 */295static struct configfs_group_operations group_children_group_ops = {296 .make_group = group_children_make_group,297};298 299static 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 305static 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. It319 * allows the init function to easily register them. Most modules320 * will only have one subsystem, and will only call register_subsystem321 * on it directly.322 */323static struct configfs_subsystem *example_subsys[] = {324 &childless_subsys.subsys,325 &simple_children_subsys,326 &group_children_subsys,327 NULL,328};329 330static 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 350out_unregister:351 for (i--; i >= 0; i--)352 configfs_unregister_subsystem(example_subsys[i]);353 354 return ret;355}356 357static 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 365module_init(configfs_example_init);366module_exit(configfs_example_exit);367MODULE_DESCRIPTION("Sample configfs module");368MODULE_LICENSE("GPL");369