// SPDX-License-Identifier: GPL-2.0-only
/*
 * The Industrial I/O core, software trigger functions
 *
 * Copyright (c) 2015 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_trigger.h>
#include <linux/iio/configfs.h>
#include <linux/configfs.h>

static struct config_group *iio_triggers_group;
static const struct config_item_type iio_trigger_type_group_type;

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

static LIST_HEAD(iio_trigger_types_list);
static DEFINE_MUTEX(iio_trigger_types_lock);

static
struct iio_sw_trigger_type *__iio_find_sw_trigger_type(const char *name,
                                                       unsigned int len)
{
        struct iio_sw_trigger_type *t = NULL, *iter;

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

        return t;
}

int iio_register_sw_trigger_type(struct iio_sw_trigger_type *t)
{
        struct iio_sw_trigger_type *iter;
        int ret = 0;

        mutex_lock(&iio_trigger_types_lock);
        iter = __iio_find_sw_trigger_type(t->name, strlen(t->name));
        if (iter)
                ret = -EBUSY;
        else
                list_add_tail(&t->list, &iio_trigger_types_list);
        mutex_unlock(&iio_trigger_types_lock);

        if (ret)
                return ret;

        t->group = configfs_register_default_group(iio_triggers_group, t->name,
                                                &iio_trigger_type_group_type);
        if (IS_ERR(t->group)) {
                mutex_lock(&iio_trigger_types_lock);
                list_del(&t->list);
                mutex_unlock(&iio_trigger_types_lock);
                ret = PTR_ERR(t->group);
        }

        return ret;
}
EXPORT_SYMBOL(iio_register_sw_trigger_type);

void iio_unregister_sw_trigger_type(struct iio_sw_trigger_type *t)
{
        struct iio_sw_trigger_type *iter;

        mutex_lock(&iio_trigger_types_lock);
        iter = __iio_find_sw_trigger_type(t->name, strlen(t->name));
        if (iter)
                list_del(&t->list);
        mutex_unlock(&iio_trigger_types_lock);

        configfs_unregister_default_group(t->group);
}
EXPORT_SYMBOL(iio_unregister_sw_trigger_type);

static
struct iio_sw_trigger_type *iio_get_sw_trigger_type(const char *name)
{
        struct iio_sw_trigger_type *t;

        mutex_lock(&iio_trigger_types_lock);
        t = __iio_find_sw_trigger_type(name, strlen(name));
        if (t && !try_module_get(t->owner))
                t = NULL;
        mutex_unlock(&iio_trigger_types_lock);

        return t;
}

struct iio_sw_trigger *iio_sw_trigger_create(const char *type, const char *name)
{
        struct iio_sw_trigger *t;
        struct iio_sw_trigger_type *tt;

        tt = iio_get_sw_trigger_type(type);
        if (!tt) {
                pr_err("Invalid trigger type: %s\n", type);
                return ERR_PTR(-EINVAL);
        }
        t = tt->ops->probe(name);
        if (IS_ERR(t))
                goto out_module_put;

        t->trigger_type = tt;

        return t;
out_module_put:
        module_put(tt->owner);
        return t;
}
EXPORT_SYMBOL(iio_sw_trigger_create);

void iio_sw_trigger_destroy(struct iio_sw_trigger *t)
{
        struct iio_sw_trigger_type *tt = t->trigger_type;

        tt->ops->remove(t);
        module_put(tt->owner);
}
EXPORT_SYMBOL(iio_sw_trigger_destroy);

static struct config_group *trigger_make_group(struct config_group *group,
                                               const char *name)
{
        struct iio_sw_trigger *t;

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

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

        return &t->group;
}

static void trigger_drop_group(struct config_group *group,
                               struct config_item *item)
{
        struct iio_sw_trigger *t = to_iio_sw_trigger(item);

        iio_sw_trigger_destroy(t);
        config_item_put(item);
}

static const struct configfs_group_operations trigger_ops = {
        .make_group     = &trigger_make_group,
        .drop_item      = &trigger_drop_group,
};

static const struct config_item_type iio_trigger_type_group_type = {
        .ct_group_ops = &trigger_ops,
        .ct_owner       = THIS_MODULE,
};

static int __init iio_sw_trigger_init(void)
{
        iio_triggers_group =
                configfs_register_default_group(&iio_configfs_subsys.su_group,
                                                "triggers",
                                                &iio_triggers_group_type);
        return PTR_ERR_OR_ZERO(iio_triggers_group);
}
module_init(iio_sw_trigger_init);

static void __exit iio_sw_trigger_exit(void)
{
        configfs_unregister_default_group(iio_triggers_group);
}
module_exit(iio_sw_trigger_exit);

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