/*
 * File: pn_dev.c
 *
 * Phonet network device
 *
 * Copyright (C) 2008 Nokia Corporation.
 *
 * Contact: Remi Denis-Courmont <remi.denis-courmont@nokia.com>
 * Original author: Sakari Ailus <sakari.ailus@nokia.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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#include <linux/kernel.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/phonet.h>
#include <net/sock.h>
#include <net/phonet/pn_dev.h>

/* when accessing, remember to lock with spin_lock(&pndevs.lock); */
struct phonet_device_list pndevs = {
        .list = LIST_HEAD_INIT(pndevs.list),
        .lock = __SPIN_LOCK_UNLOCKED(pndevs.lock),
};

/* Allocate new Phonet device. */
static struct phonet_device *__phonet_device_alloc(struct net_device *dev)
{
        struct phonet_device *pnd = kmalloc(sizeof(*pnd), GFP_ATOMIC);
        if (pnd == NULL)
                return NULL;
        pnd->netdev = dev;
        bitmap_zero(pnd->addrs, 64);

        list_add(&pnd->list, &pndevs.list);
        return pnd;
}

static struct phonet_device *__phonet_get(struct net_device *dev)
{
        struct phonet_device *pnd;

        list_for_each_entry(pnd, &pndevs.list, list) {
                if (pnd->netdev == dev)
                        return pnd;
        }
        return NULL;
}

static void __phonet_device_free(struct phonet_device *pnd)
{
        list_del(&pnd->list);
        kfree(pnd);
}

struct net_device *phonet_device_get(struct net *net)
{
        struct phonet_device *pnd;
        struct net_device *dev;

        spin_lock_bh(&pndevs.lock);
        list_for_each_entry(pnd, &pndevs.list, list) {
                dev = pnd->netdev;
                BUG_ON(!dev);

                if (dev_net(dev) == net &&
                        (dev->reg_state == NETREG_REGISTERED) &&
                        ((pnd->netdev->flags & IFF_UP)) == IFF_UP)
                        break;
                dev = NULL;
        }
        if (dev)
                dev_hold(dev);
        spin_unlock_bh(&pndevs.lock);
        return dev;
}

int phonet_address_add(struct net_device *dev, u8 addr)
{
        struct phonet_device *pnd;
        int err = 0;

        spin_lock_bh(&pndevs.lock);
        /* Find or create Phonet-specific device data */
        pnd = __phonet_get(dev);
        if (pnd == NULL)
                pnd = __phonet_device_alloc(dev);
        if (unlikely(pnd == NULL))
                err = -ENOMEM;
        else if (test_and_set_bit(addr >> 2, pnd->addrs))
                err = -EEXIST;
        spin_unlock_bh(&pndevs.lock);
        return err;
}

int phonet_address_del(struct net_device *dev, u8 addr)
{
        struct phonet_device *pnd;
        int err = 0;

        spin_lock_bh(&pndevs.lock);
        pnd = __phonet_get(dev);
        if (!pnd || !test_and_clear_bit(addr >> 2, pnd->addrs))
                err = -EADDRNOTAVAIL;
        else if (bitmap_empty(pnd->addrs, 64))
                __phonet_device_free(pnd);
        spin_unlock_bh(&pndevs.lock);
        return err;
}

/* Gets a source address toward a destination, through a interface. */
u8 phonet_address_get(struct net_device *dev, u8 addr)
{
        struct phonet_device *pnd;

        spin_lock_bh(&pndevs.lock);
        pnd = __phonet_get(dev);
        if (pnd) {
                BUG_ON(bitmap_empty(pnd->addrs, 64));

                /* Use same source address as destination, if possible */
                if (!test_bit(addr >> 2, pnd->addrs))
                        addr = find_first_bit(pnd->addrs, 64) << 2;
        } else
                addr = PN_NO_ADDR;
        spin_unlock_bh(&pndevs.lock);
        return addr;
}

int phonet_address_lookup(u8 addr)
{
        struct phonet_device *pnd;

        spin_lock_bh(&pndevs.lock);
        list_for_each_entry(pnd, &pndevs.list, list) {
                /* Don't allow unregistering devices! */
                if ((pnd->netdev->reg_state != NETREG_REGISTERED) ||
                                ((pnd->netdev->flags & IFF_UP)) != IFF_UP)
                        continue;

                if (test_bit(addr >> 2, pnd->addrs)) {
                        spin_unlock_bh(&pndevs.lock);
                        return 0;
                }
        }
        spin_unlock_bh(&pndevs.lock);
        return -EADDRNOTAVAIL;
}

/* notify Phonet of device events */
static int phonet_device_notify(struct notifier_block *me, unsigned long what,
                                void *arg)
{
        struct net_device *dev = arg;

        if (what == NETDEV_UNREGISTER) {
                struct phonet_device *pnd;

                /* Destroy phonet-specific device data */
                spin_lock_bh(&pndevs.lock);
                pnd = __phonet_get(dev);
                if (pnd)
                        __phonet_device_free(pnd);
                spin_unlock_bh(&pndevs.lock);
        }
        return 0;

}

static struct notifier_block phonet_device_notifier = {
        .notifier_call = phonet_device_notify,
        .priority = 0,
};

/* Initialize Phonet devices list */
void phonet_device_init(void)
{
        register_netdevice_notifier(&phonet_device_notifier);
}

void phonet_device_exit(void)
{
        struct phonet_device *pnd, *n;

        rtnl_unregister_all(PF_PHONET);
        rtnl_lock();
        spin_lock_bh(&pndevs.lock);

        list_for_each_entry_safe(pnd, n, &pndevs.list, list)
                __phonet_device_free(pnd);

        spin_unlock_bh(&pndevs.lock);
        rtnl_unlock();
        unregister_netdevice_notifier(&phonet_device_notifier);
}