// SPDX-License-Identifier: GPL-2.0-only
/*
 * The Industrial I/O core, software IIO devices functions
 *
 * Copyright (c) 2016 Intel Corporation
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kmod.h>
#include <linux/list.h>
#include <linux/slab.h>

#include <linux/iio/sw_device.h>
#include <linux/iio/configfs.h>
#include <linux/configfs.h>

static struct config_group *iio_devices_group;
static const struct config_item_type iio_device_type_group_type;

static const struct config_item_type iio_devices_group_type = {
        .ct_owner = THIS_MODULE,
};

static LIST_HEAD(iio_device_types_list);
static DEFINE_MUTEX(iio_device_types_lock);

static
struct iio_sw_device_type *__iio_find_sw_device_type(const char *name,
                                                     unsigned int len)
{
        struct iio_sw_device_type *d = NULL, *iter;

        list_for_each_entry(iter, &iio_device_types_list, list)
                if (!strcmp(iter->name, name)) {
                        d = iter;
                        break;
                }

        return d;
}

int iio_register_sw_device_type(struct iio_sw_device_type *d)
{
        struct iio_sw_device_type *iter;
        int ret = 0;

        mutex_lock(&iio_device_types_lock);
        iter = __iio_find_sw_device_type(d->name, strlen(d->name));
        if (iter)
                ret = -EBUSY;
        else
                list_add_tail(&d->list, &iio_device_types_list);
        mutex_unlock(&iio_device_types_lock);

        if (ret)
                return ret;

        d->group = configfs_register_default_group(iio_devices_group, d->name,
                                                &iio_device_type_group_type);
        if (IS_ERR(d->group))
                ret = PTR_ERR(d->group);

        return ret;
}
EXPORT_SYMBOL(iio_register_sw_device_type);

void iio_unregister_sw_device_type(struct iio_sw_device_type *dt)
{
        struct iio_sw_device_type *iter;

        mutex_lock(&iio_device_types_lock);
        iter = __iio_find_sw_device_type(dt->name, strlen(dt->name));
        if (iter)
                list_del(&dt->list);
        mutex_unlock(&iio_device_types_lock);

        configfs_unregister_default_group(dt->group);
}
EXPORT_SYMBOL(iio_unregister_sw_device_type);

static
struct iio_sw_device_type *iio_get_sw_device_type(const char *name)
{
        struct iio_sw_device_type *dt;

        mutex_lock(&iio_device_types_lock);
        dt = __iio_find_sw_device_type(name, strlen(name));
        if (dt && !try_module_get(dt->owner))
                dt = NULL;
        mutex_unlock(&iio_device_types_lock);

        return dt;
}

struct iio_sw_device *iio_sw_device_create(const char *type, const char *name)
{
        struct iio_sw_device *d;
        struct iio_sw_device_type *dt;

        dt = iio_get_sw_device_type(type);
        if (!dt) {
                pr_err("Invalid device type: %s\n", type);
                return ERR_PTR(-EINVAL);
        }
        d = dt->ops->probe(name);
        if (IS_ERR(d))
                goto out_module_put;

        d->device_type = dt;

        return d;
out_module_put:
        module_put(dt->owner);
        return d;
}
EXPORT_SYMBOL(iio_sw_device_create);

void iio_sw_device_destroy(struct iio_sw_device *d)
{
        struct iio_sw_device_type *dt = d->device_type;

        dt->ops->remove(d);
        module_put(dt->owner);
}
EXPORT_SYMBOL(iio_sw_device_destroy);

static struct config_group *device_make_group(struct config_group *group,
                                              const char *name)
{
        struct iio_sw_device *d;

        d = iio_sw_device_create(group->cg_item.ci_name, name);
        if (IS_ERR(d))
                return ERR_CAST(d);

        config_item_set_name(&d->group.cg_item, "%s", name);

        return &d->group;
}

static void device_drop_group(struct config_group *group,
                              struct config_item *item)
{
        struct iio_sw_device *d = to_iio_sw_device(item);

        iio_sw_device_destroy(d);
        config_item_put(item);
}

static const struct configfs_group_operations device_ops = {
        .make_group     = &device_make_group,
        .drop_item      = &device_drop_group,
};

static const struct config_item_type iio_device_type_group_type = {
        .ct_group_ops = &device_ops,
        .ct_owner       = THIS_MODULE,
};

static int __init iio_sw_device_init(void)
{
        iio_devices_group =
                configfs_register_default_group(&iio_configfs_subsys.su_group,
                                                "devices",
                                                &iio_devices_group_type);
        return PTR_ERR_OR_ZERO(iio_devices_group);
}
module_init(iio_sw_device_init);

static void __exit iio_sw_device_exit(void)
{
        configfs_unregister_default_group(iio_devices_group);
}
module_exit(iio_sw_device_exit);

MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
MODULE_DESCRIPTION("Industrial I/O software devices support");
MODULE_LICENSE("GPL v2");