// SPDX-License-Identifier: GPL-2.0-or-later
/*
* 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/kernel.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 container_of(to_configfs_subsystem(to_config_group(item)),
struct childless, subsys);
}
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);
int ret;
ret = kstrtoint(page, 10, &childless->storeme);
if (ret)
return ret;
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 container_of(item, struct simple_child, item);
}
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);
int ret;
ret = kstrtoint(page, 10, &simple_child->storeme);
if (ret)
return ret;
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 container_of(to_config_group(item),
struct simple_children, group);
}
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);
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)
{
struct configfs_subsystem *subsys;
int ret, i;
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) {
pr_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_DESCRIPTION("Sample configfs module");
MODULE_LICENSE("GPL");
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