/*
 * Network-device interface management.
 *
 * Copyright (c) 2004-2005, Keir Fraser
 *
 * 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; or, when distributed
 * separately from the Linux kernel or incorporated into other
 * software packages, subject to the following license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this source file (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#include "common.h"

#include <linux/ethtool.h>
#include <linux/rtnetlink.h>
#include <linux/if_vlan.h>

#include <xen/events.h>
#include <asm/xen/hypercall.h>

#define XENVIF_QUEUE_LENGTH 32

void xenvif_get(struct xenvif *vif)
{
        atomic_inc(&vif->refcnt);
}

void xenvif_put(struct xenvif *vif)
{
        if (atomic_dec_and_test(&vif->refcnt))
                wake_up(&vif->waiting_to_free);
}

int xenvif_schedulable(struct xenvif *vif)
{
        return netif_running(vif->dev) && netif_carrier_ok(vif->dev);
}

static int xenvif_rx_schedulable(struct xenvif *vif)
{
        return xenvif_schedulable(vif) && !xen_netbk_rx_ring_full(vif);
}

static irqreturn_t xenvif_tx_interrupt(int irq, void *dev_id)
{
        struct xenvif *vif = dev_id;

        if (vif->netbk == NULL)
                return IRQ_HANDLED;

        xen_netbk_schedule_xenvif(vif);

        return IRQ_HANDLED;
}

static irqreturn_t xenvif_rx_interrupt(int irq, void *dev_id)
{
        struct xenvif *vif = dev_id;

        if (vif->netbk == NULL)
                return IRQ_HANDLED;

        if (xenvif_rx_schedulable(vif))
                netif_wake_queue(vif->dev);

        return IRQ_HANDLED;
}

static irqreturn_t xenvif_interrupt(int irq, void *dev_id)
{
        xenvif_tx_interrupt(irq, dev_id);
        xenvif_rx_interrupt(irq, dev_id);

        return IRQ_HANDLED;
}

static int xenvif_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct xenvif *vif = netdev_priv(dev);

        BUG_ON(skb->dev != dev);

        if (vif->netbk == NULL)
                goto drop;

        /* Drop the packet if the target domain has no receive buffers. */
        if (!xenvif_rx_schedulable(vif))
                goto drop;

        /* Reserve ring slots for the worst-case number of fragments. */
        vif->rx_req_cons_peek += xen_netbk_count_skb_slots(vif, skb);
        xenvif_get(vif);

        if (vif->can_queue && xen_netbk_must_stop_queue(vif))
                netif_stop_queue(dev);

        xen_netbk_queue_tx_skb(vif, skb);

        return NETDEV_TX_OK;

 drop:
        vif->dev->stats.tx_dropped++;
        dev_kfree_skb(skb);
        return NETDEV_TX_OK;
}

void xenvif_receive_skb(struct xenvif *vif, struct sk_buff *skb)
{
        netif_rx_ni(skb);
}

void xenvif_notify_tx_completion(struct xenvif *vif)
{
        if (netif_queue_stopped(vif->dev) && xenvif_rx_schedulable(vif))
                netif_wake_queue(vif->dev);
}

static struct net_device_stats *xenvif_get_stats(struct net_device *dev)
{
        struct xenvif *vif = netdev_priv(dev);
        return &vif->dev->stats;
}

static void xenvif_up(struct xenvif *vif)
{
        xen_netbk_add_xenvif(vif);
        enable_irq(vif->tx_irq);
        if (vif->tx_irq != vif->rx_irq)
                enable_irq(vif->rx_irq);
        xen_netbk_check_rx_xenvif(vif);
}

static void xenvif_down(struct xenvif *vif)
{
        disable_irq(vif->tx_irq);
        if (vif->tx_irq != vif->rx_irq)
                disable_irq(vif->rx_irq);
        del_timer_sync(&vif->credit_timeout);
        xen_netbk_deschedule_xenvif(vif);
        xen_netbk_remove_xenvif(vif);
}

static int xenvif_open(struct net_device *dev)
{
        struct xenvif *vif = netdev_priv(dev);
        if (netif_carrier_ok(dev))
                xenvif_up(vif);
        netif_start_queue(dev);
        return 0;
}

static int xenvif_close(struct net_device *dev)
{
        struct xenvif *vif = netdev_priv(dev);
        if (netif_carrier_ok(dev))
                xenvif_down(vif);
        netif_stop_queue(dev);
        return 0;
}

static int xenvif_change_mtu(struct net_device *dev, int mtu)
{
        struct xenvif *vif = netdev_priv(dev);
        int max = vif->can_sg ? 65535 - VLAN_ETH_HLEN : ETH_DATA_LEN;

        if (mtu > max)
                return -EINVAL;
        dev->mtu = mtu;
        return 0;
}

static netdev_features_t xenvif_fix_features(struct net_device *dev,
        netdev_features_t features)
{
        struct xenvif *vif = netdev_priv(dev);

        if (!vif->can_sg)
                features &= ~NETIF_F_SG;
        if (!vif->gso && !vif->gso_prefix)
                features &= ~NETIF_F_TSO;
        if (!vif->csum)
                features &= ~NETIF_F_IP_CSUM;

        return features;
}

static const struct xenvif_stat {
        char name[ETH_GSTRING_LEN];
        u16 offset;
} xenvif_stats[] = {
        {
                "rx_gso_checksum_fixup",
                offsetof(struct xenvif, rx_gso_checksum_fixup)
        },
};

static int xenvif_get_sset_count(struct net_device *dev, int string_set)
{
        switch (string_set) {
        case ETH_SS_STATS:
                return ARRAY_SIZE(xenvif_stats);
        default:
                return -EINVAL;
        }
}

static void xenvif_get_ethtool_stats(struct net_device *dev,
                                     struct ethtool_stats *stats, u64 * data)
{
        void *vif = netdev_priv(dev);
        int i;

        for (i = 0; i < ARRAY_SIZE(xenvif_stats); i++)
                data[i] = *(unsigned long *)(vif + xenvif_stats[i].offset);
}

static void xenvif_get_strings(struct net_device *dev, u32 stringset, u8 * data)
{
        int i;

        switch (stringset) {
        case ETH_SS_STATS:
                for (i = 0; i < ARRAY_SIZE(xenvif_stats); i++)
                        memcpy(data + i * ETH_GSTRING_LEN,
                               xenvif_stats[i].name, ETH_GSTRING_LEN);
                break;
        }
}

static const struct ethtool_ops xenvif_ethtool_ops = {
        .get_link       = ethtool_op_get_link,

        .get_sset_count = xenvif_get_sset_count,
        .get_ethtool_stats = xenvif_get_ethtool_stats,
        .get_strings = xenvif_get_strings,
};

static const struct net_device_ops xenvif_netdev_ops = {
        .ndo_start_xmit = xenvif_start_xmit,
        .ndo_get_stats  = xenvif_get_stats,
        .ndo_open       = xenvif_open,
        .ndo_stop       = xenvif_close,
        .ndo_change_mtu = xenvif_change_mtu,
        .ndo_fix_features = xenvif_fix_features,
        .ndo_set_mac_address = eth_mac_addr,
        .ndo_validate_addr   = eth_validate_addr,
};

struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
                            unsigned int handle)
{
        int err;
        struct net_device *dev;
        struct xenvif *vif;
        char name[IFNAMSIZ] = {};

        snprintf(name, IFNAMSIZ - 1, "vif%u.%u", domid, handle);
        dev = alloc_netdev(sizeof(struct xenvif), name, ether_setup);
        if (dev == NULL) {
                pr_warn("Could not allocate netdev\n");
                return ERR_PTR(-ENOMEM);
        }

        SET_NETDEV_DEV(dev, parent);

        vif = netdev_priv(dev);
        vif->domid  = domid;
        vif->handle = handle;
        vif->netbk  = NULL;
        vif->can_sg = 1;
        vif->csum = 1;
        atomic_set(&vif->refcnt, 1);
        init_waitqueue_head(&vif->waiting_to_free);
        vif->dev = dev;
        INIT_LIST_HEAD(&vif->schedule_list);
        INIT_LIST_HEAD(&vif->notify_list);

        vif->credit_bytes = vif->remaining_credit = ~0UL;
        vif->credit_usec  = 0UL;
        init_timer(&vif->credit_timeout);
        /* Initialize 'expires' now: it's used to track the credit window. */
        vif->credit_timeout.expires = jiffies;

        dev->netdev_ops = &xenvif_netdev_ops;
        dev->hw_features = NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_TSO;
        dev->features = dev->hw_features;
        SET_ETHTOOL_OPS(dev, &xenvif_ethtool_ops);

        dev->tx_queue_len = XENVIF_QUEUE_LENGTH;

        /*
         * Initialise a dummy MAC address. We choose the numerically
         * largest non-broadcast address to prevent the address getting
         * stolen by an Ethernet bridge for STP purposes.
         * (FE:FF:FF:FF:FF:FF)
         */
        memset(dev->dev_addr, 0xFF, ETH_ALEN);
        dev->dev_addr[0] &= ~0x01;

        netif_carrier_off(dev);

        err = register_netdev(dev);
        if (err) {
                netdev_warn(dev, "Could not register device: err=%d\n", err);
                free_netdev(dev);
                return ERR_PTR(err);
        }

        netdev_dbg(dev, "Successfully created xenvif\n");
        return vif;
}

int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
                   unsigned long rx_ring_ref, unsigned int tx_evtchn,
                   unsigned int rx_evtchn)
{
        int err = -ENOMEM;

        /* Already connected through? */
        if (vif->tx_irq)
                return 0;

        __module_get(THIS_MODULE);

        err = xen_netbk_map_frontend_rings(vif, tx_ring_ref, rx_ring_ref);
        if (err < 0)
                goto err;

        if (tx_evtchn == rx_evtchn) {
                /* feature-split-event-channels == 0 */
                err = bind_interdomain_evtchn_to_irqhandler(
                        vif->domid, tx_evtchn, xenvif_interrupt, 0,
                        vif->dev->name, vif);
                if (err < 0)
                        goto err_unmap;
                vif->tx_irq = vif->rx_irq = err;
                disable_irq(vif->tx_irq);
        } else {
                /* feature-split-event-channels == 1 */
                snprintf(vif->tx_irq_name, sizeof(vif->tx_irq_name),
                         "%s-tx", vif->dev->name);
                err = bind_interdomain_evtchn_to_irqhandler(
                        vif->domid, tx_evtchn, xenvif_tx_interrupt, 0,
                        vif->tx_irq_name, vif);
                if (err < 0)
                        goto err_unmap;
                vif->tx_irq = err;
                disable_irq(vif->tx_irq);

                snprintf(vif->rx_irq_name, sizeof(vif->rx_irq_name),
                         "%s-rx", vif->dev->name);
                err = bind_interdomain_evtchn_to_irqhandler(
                        vif->domid, rx_evtchn, xenvif_rx_interrupt, 0,
                        vif->rx_irq_name, vif);
                if (err < 0)
                        goto err_tx_unbind;
                vif->rx_irq = err;
                disable_irq(vif->rx_irq);
        }

        xenvif_get(vif);

        rtnl_lock();
        if (!vif->can_sg && vif->dev->mtu > ETH_DATA_LEN)
                dev_set_mtu(vif->dev, ETH_DATA_LEN);
        netdev_update_features(vif->dev);
        netif_carrier_on(vif->dev);
        if (netif_running(vif->dev))
                xenvif_up(vif);
        rtnl_unlock();

        return 0;
err_tx_unbind:
        unbind_from_irqhandler(vif->tx_irq, vif);
        vif->tx_irq = 0;
err_unmap:
        xen_netbk_unmap_frontend_rings(vif);
err:
        module_put(THIS_MODULE);
        return err;
}

void xenvif_carrier_off(struct xenvif *vif)
{
        struct net_device *dev = vif->dev;

        rtnl_lock();
        netif_carrier_off(dev); /* discard queued packets */
        if (netif_running(dev))
                xenvif_down(vif);
        rtnl_unlock();
        xenvif_put(vif);
}

void xenvif_disconnect(struct xenvif *vif)
{
        /* Disconnect funtion might get called by generic framework
         * even before vif connects, so we need to check if we really
         * need to do a module_put.
         */
        int need_module_put = 0;

        if (netif_carrier_ok(vif->dev))
                xenvif_carrier_off(vif);

        atomic_dec(&vif->refcnt);
        wait_event(vif->waiting_to_free, atomic_read(&vif->refcnt) == 0);

        if (vif->tx_irq) {
                if (vif->tx_irq == vif->rx_irq)
                        unbind_from_irqhandler(vif->tx_irq, vif);
                else {
                        unbind_from_irqhandler(vif->tx_irq, vif);
                        unbind_from_irqhandler(vif->rx_irq, vif);
                }
                /* vif->irq is valid, we had a module_get in
                 * xenvif_connect.
                 */
                need_module_put = 1;
        }

        unregister_netdev(vif->dev);

        xen_netbk_unmap_frontend_rings(vif);

        free_netdev(vif->dev);

        if (need_module_put)
                module_put(THIS_MODULE);
}