// SPDX-License-Identifier: GPL-2.0-only
/*
 *
 * Authors:
 * (C) 2015 Pengutronix, Alexander Aring <aar@pengutronix.de>
 */

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

#include <net/6lowpan.h>
#include <net/addrconf.h>

#include "6lowpan_i.h"

int lowpan_register_netdevice(struct net_device *dev,
                              enum lowpan_lltypes lltype)
{
        int i, ret;

        switch (lltype) {
        case LOWPAN_LLTYPE_IEEE802154:
                dev->addr_len = EUI64_ADDR_LEN;
                break;

        case LOWPAN_LLTYPE_BTLE:
                dev->addr_len = ETH_ALEN;
                break;
        }

        dev->type = ARPHRD_6LOWPAN;
        dev->mtu = IPV6_MIN_MTU;

        lowpan_dev(dev)->lltype = lltype;

        spin_lock_init(&lowpan_dev(dev)->ctx.lock);
        for (i = 0; i < LOWPAN_IPHC_CTX_TABLE_SIZE; i++)
                lowpan_dev(dev)->ctx.table[i].id = i;

        dev->ndisc_ops = &lowpan_ndisc_ops;

        ret = register_netdevice(dev);
        if (ret < 0)
                return ret;

        lowpan_dev_debugfs_init(dev);

        return ret;
}
EXPORT_SYMBOL(lowpan_register_netdevice);

int lowpan_register_netdev(struct net_device *dev,
                           enum lowpan_lltypes lltype)
{
        int ret;

        rtnl_lock();
        ret = lowpan_register_netdevice(dev, lltype);
        rtnl_unlock();
        return ret;
}
EXPORT_SYMBOL(lowpan_register_netdev);

void lowpan_unregister_netdevice(struct net_device *dev)
{
        unregister_netdevice(dev);
        lowpan_dev_debugfs_exit(dev);
}
EXPORT_SYMBOL(lowpan_unregister_netdevice);

void lowpan_unregister_netdev(struct net_device *dev)
{
        rtnl_lock();
        lowpan_unregister_netdevice(dev);
        rtnl_unlock();
}
EXPORT_SYMBOL(lowpan_unregister_netdev);

int addrconf_ifid_802154_6lowpan(u8 *eui, struct net_device *dev)
{
        struct wpan_dev *wpan_dev = lowpan_802154_dev(dev)->wdev->ieee802154_ptr;

        /* Set short_addr autoconfiguration if short_addr is present only */
        if (!lowpan_802154_is_valid_src_short_addr(wpan_dev->short_addr))
                return -1;

        /* For either address format, all zero addresses MUST NOT be used */
        if (wpan_dev->pan_id == cpu_to_le16(0x0000) &&
            wpan_dev->short_addr == cpu_to_le16(0x0000))
                return -1;

        /* Alternatively, if no PAN ID is known, 16 zero bits may be used */
        if (wpan_dev->pan_id == cpu_to_le16(IEEE802154_PAN_ID_BROADCAST))
                memset(eui, 0, 2);
        else
                ieee802154_le16_to_be16(eui, &wpan_dev->pan_id);

        /* The "Universal/Local" (U/L) bit shall be set to zero */
        eui[0] &= ~2;
        eui[2] = 0;
        eui[3] = 0xFF;
        eui[4] = 0xFE;
        eui[5] = 0;
        ieee802154_le16_to_be16(&eui[6], &wpan_dev->short_addr);
        return 0;
}

static int lowpan_event(struct notifier_block *unused,
                        unsigned long event, void *ptr)
{
        struct net_device *dev = netdev_notifier_info_to_dev(ptr);
        struct inet6_dev *idev;
        struct in6_addr addr;
        int i;

        if (dev->type != ARPHRD_6LOWPAN)
                return NOTIFY_DONE;

        idev = __in6_dev_get(dev);
        if (!idev)
                return NOTIFY_DONE;

        switch (event) {
        case NETDEV_UP:
        case NETDEV_CHANGE:
                /* (802.15.4 6LoWPAN short address slaac handling */
                if (lowpan_is_ll(dev, LOWPAN_LLTYPE_IEEE802154) &&
                    addrconf_ifid_802154_6lowpan(addr.s6_addr + 8, dev) == 0) {
                        __ipv6_addr_set_half(&addr.s6_addr32[0],
                                             htonl(0xFE800000), 0);
                        addrconf_add_linklocal(idev, &addr, 0);
                }
                break;
        case NETDEV_DOWN:
                for (i = 0; i < LOWPAN_IPHC_CTX_TABLE_SIZE; i++)
                        clear_bit(LOWPAN_IPHC_CTX_FLAG_ACTIVE,
                                  &lowpan_dev(dev)->ctx.table[i].flags);
                break;
        default:
                return NOTIFY_DONE;
        }

        return NOTIFY_OK;
}

static struct notifier_block lowpan_notifier = {
        .notifier_call = lowpan_event,
};

static int __init lowpan_module_init(void)
{
        int ret;

        lowpan_debugfs_init();

        ret = register_netdevice_notifier(&lowpan_notifier);
        if (ret < 0) {
                lowpan_debugfs_exit();
                return ret;
        }

        request_module_nowait("nhc_dest");
        request_module_nowait("nhc_fragment");
        request_module_nowait("nhc_hop");
        request_module_nowait("nhc_ipv6");
        request_module_nowait("nhc_mobility");
        request_module_nowait("nhc_routing");
        request_module_nowait("nhc_udp");

        return 0;
}

static void __exit lowpan_module_exit(void)
{
        lowpan_debugfs_exit();
        unregister_netdevice_notifier(&lowpan_notifier);
}

module_init(lowpan_module_init);
module_exit(lowpan_module_exit);

MODULE_DESCRIPTION("IPv6 over Low-Power Wireless Personal Area Network core module");
MODULE_LICENSE("GPL");