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/*
* LDT - Linux Driver Template - basic configfs
*
* Copyright (C) 2012 Constantine Shulyupin http://www.makelinux.net/
*
* Dual BSD/GPL License
*
* based on configfs_example_explicit.c and much more simple, without containers, just 70 LOC
*
* Sample usage:
* sudo insmod ldt_configfs_basic.ko
* ls /configfs/ldt_configfs_basic/
* sudo sh -c "echo 123 > /configfs/ldt_configfs_basic/parameter"
* cat /configfs/ldt_configfs_basic/parameter
*
*/
#include <linux/module.h>
#include <linux/configfs.h>
static int parameter;
static struct configfs_attribute ldt_parameter_attr = {
.ca_owner = THIS_MODULE, .ca_name = "parameter",
.ca_mode = S_IRUGO | S_IWUSR
};
static struct configfs_attribute ldt_description_attr = {
.ca_owner = THIS_MODULE, .ca_name = "description",
.ca_mode = S_IRUGO
};
static struct configfs_attribute *ldt_attrs[] = {
&ldt_description_attr,
&ldt_parameter_attr,
NULL,
};
static ssize_t ldt_attr_show(struct config_item *item, struct configfs_attribute *attr, char *page)
{
ssize_t ret = -EINVAL;
if (attr == &ldt_description_attr)
return sprintf(page, "basic sample of configfs\n");
else if (attr == &ldt_parameter_attr)
return sprintf(page, "%d\n", parameter);
return ret;
}
static ssize_t ldt_attr_store(struct config_item *item, struct configfs_attribute *attr, const char *page, size_t count)
{
ssize_t ret = -EINVAL;
if (attr == &ldt_parameter_attr) {
ret = kstrtoint(page, 0, &parameter);
if (ret)
return ret;
ret = count;
}
return ret;
}
static struct config_item_type ci_type = {
.ct_item_ops = (struct configfs_item_operations[]){ {
.show_attribute = ldt_attr_show,
.store_attribute = ldt_attr_store,} },
.ct_attrs = ldt_attrs,
.ct_owner = THIS_MODULE,
};
static struct configfs_subsystem ldt_subsys = {
.su_group = {
.cg_item = {
.ci_namebuf = KBUILD_MODNAME,
.ci_type = &ci_type,
},
},
};
static int __init configfs_example_init(void)
{
int ret;
config_group_init(&ldt_subsys.su_group);
mutex_init(&ldt_subsys.su_mutex);
ret = configfs_register_subsystem(&ldt_subsys);
if (ret)
pr_err("Error %d while registering subsystem %s\n",
ret, ldt_subsys.su_group.cg_item.ci_namebuf);
return ret;
}
static void __exit configfs_example_exit(void)
{
configfs_unregister_subsystem(&ldt_subsys);
}
module_init(configfs_example_init);
module_exit(configfs_example_exit);
MODULE_LICENSE("GPL");
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