// SPDX-License-Identifier: GPL-2.0-or-later /* * vim: noexpandtab ts=8 sts=0 sw=8: * * configfs_example_macros.c - This file is a demonstration module * containing a number of configfs subsystems. It uses the helper * macros defined by configfs.h * * Based on sysfs: * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel * * configfs Copyright (C) 2005 Oracle. All rights reserved. */ #include <linux/init.h> #include <linux/module.h> #include <linux/slab.h> #include <linux/configfs.h> /* * 01-childless * * This first example is a childless subsystem. It cannot create * any config_items. It just has attributes. * * Note that we are enclosing the configfs_subsystem inside a container. * This is not necessary if a subsystem has no attributes directly * on the subsystem. See the next example, 02-simple-children, for * such a subsystem. */ struct childless { struct configfs_subsystem subsys; int showme; int storeme; }; static inline struct childless *to_childless(struct config_item *item) { return item ? container_of(to_configfs_subsystem(to_config_group(item)), struct childless, subsys) : NULL; } static ssize_t childless_showme_show(struct config_item *item, char *page) { struct childless *childless = to_childless(item); ssize_t pos; pos = sprintf(page, "%d\n", childless->showme); childless->showme++; return pos; } static ssize_t childless_storeme_show(struct config_item *item, char *page) { return sprintf(page, "%d\n", to_childless(item)->storeme); } static ssize_t childless_storeme_store(struct config_item *item, const char *page, size_t count) { struct childless *childless = to_childless(item); unsigned long tmp; char *p = (char *) page; tmp = simple_strtoul(p, &p, 10); if (!p || (*p && (*p != '\n'))) return -EINVAL; if (tmp > INT_MAX) return -ERANGE; childless->storeme = tmp; return count; } static ssize_t childless_description_show(struct config_item *item, char *page) { return sprintf(page, "[01-childless]\n" "\n" "The childless subsystem is the simplest possible subsystem in\n" "configfs. It does not support the creation of child config_items.\n" "It only has a few attributes. In fact, it isn't much different\n" "than a directory in /proc.\n"); } CONFIGFS_ATTR_RO(childless_, showme); CONFIGFS_ATTR(childless_, storeme); CONFIGFS_ATTR_RO(childless_, description); static struct configfs_attribute *childless_attrs[] = { &childless_attr_showme, &childless_attr_storeme, &childless_attr_description, NULL, }; static const struct config_item_type childless_type = { .ct_attrs = childless_attrs, .ct_owner = THIS_MODULE, }; static struct childless childless_subsys = { .subsys = { .su_group = { .cg_item = { .ci_namebuf = "01-childless", .ci_type = &childless_type, }, }, }, }; /* ----------------------------------------------------------------- */ /* * 02-simple-children * * This example merely has a simple one-attribute child. Note that * there is no extra attribute structure, as the child's attribute is * known from the get-go. Also, there is no container for the * subsystem, as it has no attributes of its own. */ struct simple_child { struct config_item item; int storeme; }; static inline struct simple_child *to_simple_child(struct config_item *item) { return item ? container_of(item, struct simple_child, item) : NULL; } static ssize_t simple_child_storeme_show(struct config_item *item, char *page) { return sprintf(page, "%d\n", to_simple_child(item)->storeme); } static ssize_t simple_child_storeme_store(struct config_item *item, const char *page, size_t count) { struct simple_child *simple_child = to_simple_child(item); unsigned long tmp; char *p = (char *) page; tmp = simple_strtoul(p, &p, 10); if (!p || (*p && (*p != '\n'))) return -EINVAL; if (tmp > INT_MAX) return -ERANGE; simple_child->storeme = tmp; return count; } CONFIGFS_ATTR(simple_child_, storeme); static struct configfs_attribute *simple_child_attrs[] = { &simple_child_attr_storeme, NULL, }; static void simple_child_release(struct config_item *item) { kfree(to_simple_child(item)); } static struct configfs_item_operations simple_child_item_ops = { .release = simple_child_release, }; static const struct config_item_type simple_child_type = { .ct_item_ops = &simple_child_item_ops, .ct_attrs = simple_child_attrs, .ct_owner = THIS_MODULE, }; struct simple_children { struct config_group group; }; static inline struct simple_children *to_simple_children(struct config_item *item) { return item ? container_of(to_config_group(item), struct simple_children, group) : NULL; } static struct config_item *simple_children_make_item(struct config_group *group, const char *name) { struct simple_child *simple_child; simple_child = kzalloc(sizeof(struct simple_child), GFP_KERNEL); if (!simple_child) return ERR_PTR(-ENOMEM); config_item_init_type_name(&simple_child->item, name, &simple_child_type); simple_child->storeme = 0; return &simple_child->item; } static ssize_t simple_children_description_show(struct config_item *item, char *page) { return sprintf(page, "[02-simple-children]\n" "\n" "This subsystem allows the creation of child config_items. These\n" "items have only one attribute that is readable and writeable.\n"); } CONFIGFS_ATTR_RO(simple_children_, description); static struct configfs_attribute *simple_children_attrs[] = { &simple_children_attr_description, NULL, }; static void simple_children_release(struct config_item *item) { kfree(to_simple_children(item)); } static struct configfs_item_operations simple_children_item_ops = { .release = simple_children_release, }; /* * Note that, since no extra work is required on ->drop_item(), * no ->drop_item() is provided. */ static struct configfs_group_operations simple_children_group_ops = { .make_item = simple_children_make_item, }; static const struct config_item_type simple_children_type = { .ct_item_ops = &simple_children_item_ops, .ct_group_ops = &simple_children_group_ops, .ct_attrs = simple_children_attrs, .ct_owner = THIS_MODULE, }; static struct configfs_subsystem simple_children_subsys = { .su_group = { .cg_item = { .ci_namebuf = "02-simple-children", .ci_type = &simple_children_type, }, }, }; /* ----------------------------------------------------------------- */ /* * 03-group-children * * This example reuses the simple_children group from above. However, * the simple_children group is not the subsystem itself, it is a * child of the subsystem. Creation of a group in the subsystem creates * a new simple_children group. That group can then have simple_child * children of its own. */ static struct config_group *group_children_make_group( struct config_group *group, const char *name) { struct simple_children *simple_children; simple_children = kzalloc(sizeof(struct simple_children), GFP_KERNEL); if (!simple_children) return ERR_PTR(-ENOMEM); config_group_init_type_name(&simple_children->group, name, &simple_children_type); return &simple_children->group; } static ssize_t group_children_description_show(struct config_item *item, char *page) { return sprintf(page, "[03-group-children]\n" "\n" "This subsystem allows the creation of child config_groups. These\n" "groups are like the subsystem simple-children.\n"); } CONFIGFS_ATTR_RO(group_children_, description); static struct configfs_attribute *group_children_attrs[] = { &group_children_attr_description, NULL, }; /* * Note that, since no extra work is required on ->drop_item(), * no ->drop_item() is provided. */ static struct configfs_group_operations group_children_group_ops = { .make_group = group_children_make_group, }; static const struct config_item_type group_children_type = { .ct_group_ops = &group_children_group_ops, .ct_attrs = group_children_attrs, .ct_owner = THIS_MODULE, }; static struct configfs_subsystem group_children_subsys = { .su_group = { .cg_item = { .ci_namebuf = "03-group-children", .ci_type = &group_children_type, }, }, }; /* ----------------------------------------------------------------- */ /* * We're now done with our subsystem definitions. * For convenience in this module, here's a list of them all. It * allows the init function to easily register them. Most modules * will only have one subsystem, and will only call register_subsystem * on it directly. */ static struct configfs_subsystem *example_subsys[] = { &childless_subsys.subsys, &simple_children_subsys, &group_children_subsys, NULL, }; static int __init configfs_example_init(void) { int ret; int i; struct configfs_subsystem *subsys; for (i = 0; example_subsys[i]; i++) { subsys = example_subsys[i]; config_group_init(&subsys->su_group); mutex_init(&subsys->su_mutex); ret = configfs_register_subsystem(subsys); if (ret) { printk(KERN_ERR "Error %d while registering subsystem %s\n", ret, subsys->su_group.cg_item.ci_namebuf); goto out_unregister; } } return 0; out_unregister: for (i--; i >= 0; i--) configfs_unregister_subsystem(example_subsys[i]); return ret; } static void __exit configfs_example_exit(void) { int i; for (i = 0; example_subsys[i]; i++) configfs_unregister_subsystem(example_subsys[i]); } module_init(configfs_example_init); module_exit(configfs_example_exit); MODULE_LICENSE("GPL");