/* Copyright 2011, Siemens AG
 * written by Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
 */

/* Based on patches from Jon Smirl <jonsmirl@gmail.com>
 * Copyright (c) 2011 Jon Smirl <jonsmirl@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

/* Jon's code is based on 6lowpan implementation for Contiki which is:
 * Copyright (c) 2008, Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/ieee802154.h>
#include <linux/if_arp.h>

#include <net/ipv6.h>
#include <net/netdev_lock.h>

#include "6lowpan_i.h"

static int open_count;

static const struct header_ops lowpan_header_ops = {
        .create = lowpan_header_create,
};

static int lowpan_dev_init(struct net_device *ldev)
{
        netdev_lockdep_set_classes(ldev);

        return 0;
}

static int lowpan_open(struct net_device *dev)
{
        if (!open_count)
                lowpan_rx_init();
        open_count++;
        return 0;
}

static int lowpan_stop(struct net_device *dev)
{
        open_count--;
        if (!open_count)
                lowpan_rx_exit();
        return 0;
}

static int lowpan_neigh_construct(struct net_device *dev, struct neighbour *n)
{
        struct lowpan_802154_neigh *neigh = lowpan_802154_neigh(neighbour_priv(n));

        /* default no short_addr is available for a neighbour */
        neigh->short_addr = cpu_to_le16(IEEE802154_ADDR_SHORT_UNSPEC);
        return 0;
}

static int lowpan_get_iflink(const struct net_device *dev)
{
        return READ_ONCE(lowpan_802154_dev(dev)->wdev->ifindex);
}

static const struct net_device_ops lowpan_netdev_ops = {
        .ndo_init               = lowpan_dev_init,
        .ndo_start_xmit         = lowpan_xmit,
        .ndo_open               = lowpan_open,
        .ndo_stop               = lowpan_stop,
        .ndo_neigh_construct    = lowpan_neigh_construct,
        .ndo_get_iflink         = lowpan_get_iflink,
};

static void lowpan_setup(struct net_device *ldev)
{
        memset(ldev->broadcast, 0xff, IEEE802154_ADDR_LEN);
        /* We need an ipv6hdr as minimum len when calling xmit */
        ldev->hard_header_len   = sizeof(struct ipv6hdr);
        ldev->flags             = IFF_BROADCAST | IFF_MULTICAST;
        ldev->priv_flags        |= IFF_NO_QUEUE;

        ldev->netdev_ops        = &lowpan_netdev_ops;
        ldev->header_ops        = &lowpan_header_ops;
        ldev->needs_free_netdev = true;
        ldev->netns_immutable   = true;
}

static int lowpan_validate(struct nlattr *tb[], struct nlattr *data[],
                           struct netlink_ext_ack *extack)
{
        if (tb[IFLA_ADDRESS]) {
                if (nla_len(tb[IFLA_ADDRESS]) != IEEE802154_ADDR_LEN)
                        return -EINVAL;
        }
        return 0;
}

static int lowpan_newlink(struct net_device *ldev,
                          struct rtnl_newlink_params *params,
                          struct netlink_ext_ack *extack)
{
        struct nlattr **tb = params->tb;
        struct net_device *wdev;
        int ret;

        ASSERT_RTNL();

        pr_debug("adding new link\n");

        if (!tb[IFLA_LINK])
                return -EINVAL;
        if (params->link_net && !net_eq(params->link_net, dev_net(ldev)))
                return -EINVAL;
        /* find and hold wpan device */
        wdev = dev_get_by_index(dev_net(ldev), nla_get_u32(tb[IFLA_LINK]));
        if (!wdev)
                return -ENODEV;
        if (wdev->type != ARPHRD_IEEE802154) {
                dev_put(wdev);
                return -EINVAL;
        }

        if (wdev->ieee802154_ptr->lowpan_dev) {
                dev_put(wdev);
                return -EBUSY;
        }

        lowpan_802154_dev(ldev)->wdev = wdev;
        /* Set the lowpan hardware address to the wpan hardware address. */
        __dev_addr_set(ldev, wdev->dev_addr, IEEE802154_ADDR_LEN);
        /* We need headroom for possible wpan_dev_hard_header call and tailroom
         * for encryption/fcs handling. The lowpan interface will replace
         * the IPv6 header with 6LoWPAN header. At worst case the 6LoWPAN
         * header has LOWPAN_IPHC_MAX_HEADER_LEN more bytes than the IPv6
         * header.
         */
        ldev->needed_headroom = LOWPAN_IPHC_MAX_HEADER_LEN +
                                wdev->needed_headroom;
        ldev->needed_tailroom = wdev->needed_tailroom;

        ldev->neigh_priv_len = sizeof(struct lowpan_802154_neigh);

        ret = lowpan_register_netdevice(ldev, LOWPAN_LLTYPE_IEEE802154);
        if (ret < 0) {
                dev_put(wdev);
                return ret;
        }

        wdev->ieee802154_ptr->lowpan_dev = ldev;
        return 0;
}

static void lowpan_dellink(struct net_device *ldev, struct list_head *head)
{
        struct net_device *wdev = lowpan_802154_dev(ldev)->wdev;

        ASSERT_RTNL();

        wdev->ieee802154_ptr->lowpan_dev = NULL;
        lowpan_unregister_netdevice(ldev);
        dev_put(wdev);
}

static struct rtnl_link_ops lowpan_link_ops __read_mostly = {
        .kind           = "lowpan",
        .priv_size      = LOWPAN_PRIV_SIZE(sizeof(struct lowpan_802154_dev)),
        .setup          = lowpan_setup,
        .newlink        = lowpan_newlink,
        .dellink        = lowpan_dellink,
        .validate       = lowpan_validate,
};

static inline int __init lowpan_netlink_init(void)
{
        return rtnl_link_register(&lowpan_link_ops);
}

static inline void lowpan_netlink_fini(void)
{
        rtnl_link_unregister(&lowpan_link_ops);
}

static int lowpan_device_event(struct notifier_block *unused,
                               unsigned long event, void *ptr)
{
        struct net_device *ndev = netdev_notifier_info_to_dev(ptr);
        struct wpan_dev *wpan_dev;

        if (ndev->type != ARPHRD_IEEE802154)
                return NOTIFY_DONE;
        wpan_dev = ndev->ieee802154_ptr;
        if (!wpan_dev)
                return NOTIFY_DONE;

        switch (event) {
        case NETDEV_UNREGISTER:
                /* Check if wpan interface is unregistered that we
                 * also delete possible lowpan interfaces which belongs
                 * to the wpan interface.
                 */
                if (wpan_dev->lowpan_dev)
                        lowpan_dellink(wpan_dev->lowpan_dev, NULL);
                break;
        default:
                return NOTIFY_DONE;
        }

        return NOTIFY_OK;
}

static struct notifier_block lowpan_dev_notifier = {
        .notifier_call = lowpan_device_event,
};

static int __init lowpan_init_module(void)
{
        int err = 0;

        err = lowpan_net_frag_init();
        if (err < 0)
                goto out;

        err = lowpan_netlink_init();
        if (err < 0)
                goto out_frag;

        err = register_netdevice_notifier(&lowpan_dev_notifier);
        if (err < 0)
                goto out_pack;

        return 0;

out_pack:
        lowpan_netlink_fini();
out_frag:
        lowpan_net_frag_exit();
out:
        return err;
}

static void __exit lowpan_cleanup_module(void)
{
        lowpan_netlink_fini();

        lowpan_net_frag_exit();

        unregister_netdevice_notifier(&lowpan_dev_notifier);
}

module_init(lowpan_init_module);
module_exit(lowpan_cleanup_module);
MODULE_DESCRIPTION("IPv6 over Low power Wireless Personal Area Network IEEE 802.15.4 core");
MODULE_LICENSE("GPL");
MODULE_ALIAS_RTNL_LINK("lowpan");