/*
 * Copyright (c) 2009, Microsoft Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 * Authors:
 *   Haiyang Zhang <haiyangz@microsoft.com>
 *   Hank Janssen  <hjanssen@microsoft.com>
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/init.h>
#include <linux/atomic.h>
#include <linux/module.h>
#include <linux/highmem.h>
#include <linux/device.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <linux/netdevice.h>
#include <linux/inetdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/if_vlan.h>
#include <linux/in.h>
#include <linux/slab.h>
#include <net/arp.h>
#include <net/route.h>
#include <net/sock.h>
#include <net/pkt_sched.h>

#include "hyperv_net.h"

struct net_device_context {
        /* point back to our device context */
        struct hv_device *device_ctx;
        struct delayed_work dwork;
        struct work_struct work;
};

#define RING_SIZE_MIN 64
static int ring_size = 128;
module_param(ring_size, int, S_IRUGO);
MODULE_PARM_DESC(ring_size, "Ring buffer size (# of pages)");

static void do_set_multicast(struct work_struct *w)
{
        struct net_device_context *ndevctx =
                container_of(w, struct net_device_context, work);
        struct netvsc_device *nvdev;
        struct rndis_device *rdev;

        nvdev = hv_get_drvdata(ndevctx->device_ctx);
        if (nvdev == NULL || nvdev->ndev == NULL)
                return;

        rdev = nvdev->extension;
        if (rdev == NULL)
                return;

        if (nvdev->ndev->flags & IFF_PROMISC)
                rndis_filter_set_packet_filter(rdev,
                        NDIS_PACKET_TYPE_PROMISCUOUS);
        else
                rndis_filter_set_packet_filter(rdev,
                        NDIS_PACKET_TYPE_BROADCAST |
                        NDIS_PACKET_TYPE_ALL_MULTICAST |
                        NDIS_PACKET_TYPE_DIRECTED);
}

static void netvsc_set_multicast_list(struct net_device *net)
{
        struct net_device_context *net_device_ctx = netdev_priv(net);

        schedule_work(&net_device_ctx->work);
}

static int netvsc_open(struct net_device *net)
{
        struct net_device_context *net_device_ctx = netdev_priv(net);
        struct hv_device *device_obj = net_device_ctx->device_ctx;
        int ret = 0;

        /* Open up the device */
        ret = rndis_filter_open(device_obj);
        if (ret != 0) {
                netdev_err(net, "unable to open device (ret %d).\n", ret);
                return ret;
        }

        netif_start_queue(net);

        return ret;
}

static int netvsc_close(struct net_device *net)
{
        struct net_device_context *net_device_ctx = netdev_priv(net);
        struct hv_device *device_obj = net_device_ctx->device_ctx;
        int ret;

        netif_tx_disable(net);

        /* Make sure netvsc_set_multicast_list doesn't re-enable filter! */
        cancel_work_sync(&net_device_ctx->work);
        ret = rndis_filter_close(device_obj);
        if (ret != 0)
                netdev_err(net, "unable to close device (ret %d).\n", ret);

        return ret;
}

static void netvsc_xmit_completion(void *context)
{
        struct hv_netvsc_packet *packet = (struct hv_netvsc_packet *)context;
        struct sk_buff *skb = (struct sk_buff *)
                (unsigned long)packet->completion.send.send_completion_tid;

        kfree(packet);

        if (skb)
                dev_kfree_skb_any(skb);
}

static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
{
        struct net_device_context *net_device_ctx = netdev_priv(net);
        struct hv_netvsc_packet *packet;
        int ret;
        unsigned int i, num_pages, npg_data;

        /* Add multipages for skb->data and additional 2 for RNDIS */
        npg_data = (((unsigned long)skb->data + skb_headlen(skb) - 1)
                >> PAGE_SHIFT) - ((unsigned long)skb->data >> PAGE_SHIFT) + 1;
        num_pages = skb_shinfo(skb)->nr_frags + npg_data + 2;

        /* Allocate a netvsc packet based on # of frags. */
        packet = kzalloc(sizeof(struct hv_netvsc_packet) +
                         (num_pages * sizeof(struct hv_page_buffer)) +
                         sizeof(struct rndis_filter_packet) +
                         NDIS_VLAN_PPI_SIZE, GFP_ATOMIC);
        if (!packet) {
                /* out of memory, drop packet */
                netdev_err(net, "unable to allocate hv_netvsc_packet\n");

                dev_kfree_skb(skb);
                net->stats.tx_dropped++;
                return NETDEV_TX_OK;
        }

        packet->vlan_tci = skb->vlan_tci;

        packet->extension = (void *)(unsigned long)packet +
                                sizeof(struct hv_netvsc_packet) +
                                    (num_pages * sizeof(struct hv_page_buffer));

        /* If the rndis msg goes beyond 1 page, we will add 1 later */
        packet->page_buf_cnt = num_pages - 1;

        /* Initialize it from the skb */
        packet->total_data_buflen = skb->len;

        /* Start filling in the page buffers starting after RNDIS buffer. */
        packet->page_buf[1].pfn = virt_to_phys(skb->data) >> PAGE_SHIFT;
        packet->page_buf[1].offset
                = (unsigned long)skb->data & (PAGE_SIZE - 1);
        if (npg_data == 1)
                packet->page_buf[1].len = skb_headlen(skb);
        else
                packet->page_buf[1].len = PAGE_SIZE
                        - packet->page_buf[1].offset;

        for (i = 2; i <= npg_data; i++) {
                packet->page_buf[i].pfn = virt_to_phys(skb->data
                        + PAGE_SIZE * (i-1)) >> PAGE_SHIFT;
                packet->page_buf[i].offset = 0;
                packet->page_buf[i].len = PAGE_SIZE;
        }
        if (npg_data > 1)
                packet->page_buf[npg_data].len = (((unsigned long)skb->data
                        + skb_headlen(skb) - 1) & (PAGE_SIZE - 1)) + 1;

        /* Additional fragments are after SKB data */
        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
                const skb_frag_t *f = &skb_shinfo(skb)->frags[i];

                packet->page_buf[i+npg_data+1].pfn =
                        page_to_pfn(skb_frag_page(f));
                packet->page_buf[i+npg_data+1].offset = f->page_offset;
                packet->page_buf[i+npg_data+1].len = skb_frag_size(f);
        }

        /* Set the completion routine */
        packet->completion.send.send_completion = netvsc_xmit_completion;
        packet->completion.send.send_completion_ctx = packet;
        packet->completion.send.send_completion_tid = (unsigned long)skb;

        ret = rndis_filter_send(net_device_ctx->device_ctx,
                                  packet);
        if (ret == 0) {
                net->stats.tx_bytes += skb->len;
                net->stats.tx_packets++;
        } else {
                kfree(packet);
                if (ret != -EAGAIN) {
                        dev_kfree_skb_any(skb);
                        net->stats.tx_dropped++;
                }
        }

        return (ret == -EAGAIN) ? NETDEV_TX_BUSY : NETDEV_TX_OK;
}

/*
 * netvsc_linkstatus_callback - Link up/down notification
 */
void netvsc_linkstatus_callback(struct hv_device *device_obj,
                                       unsigned int status)
{
        struct net_device *net;
        struct net_device_context *ndev_ctx;
        struct netvsc_device *net_device;

        net_device = hv_get_drvdata(device_obj);
        net = net_device->ndev;

        if (!net) {
                netdev_err(net, "got link status but net device "
                                "not initialized yet\n");
                return;
        }

        if (status == 1) {
                netif_carrier_on(net);
                ndev_ctx = netdev_priv(net);
                schedule_delayed_work(&ndev_ctx->dwork, 0);
                schedule_delayed_work(&ndev_ctx->dwork, msecs_to_jiffies(20));
        } else {
                netif_carrier_off(net);
        }
}

/*
 * netvsc_recv_callback -  Callback when we receive a packet from the
 * "wire" on the specified device.
 */
int netvsc_recv_callback(struct hv_device *device_obj,
                                struct hv_netvsc_packet *packet)
{
        struct net_device *net;
        struct sk_buff *skb;

        net = ((struct netvsc_device *)hv_get_drvdata(device_obj))->ndev;
        if (!net || net->reg_state != NETREG_REGISTERED) {
                packet->status = NVSP_STAT_FAIL;
                return 0;
        }

        /* Allocate a skb - TODO direct I/O to pages? */
        skb = netdev_alloc_skb_ip_align(net, packet->total_data_buflen);
        if (unlikely(!skb)) {
                ++net->stats.rx_dropped;
                packet->status = NVSP_STAT_FAIL;
                return 0;
        }

        /*
         * Copy to skb. This copy is needed here since the memory pointed by
         * hv_netvsc_packet cannot be deallocated
         */
        memcpy(skb_put(skb, packet->total_data_buflen), packet->data,
                packet->total_data_buflen);

        skb->protocol = eth_type_trans(skb, net);
        skb->ip_summed = CHECKSUM_NONE;
        if (packet->vlan_tci & VLAN_TAG_PRESENT)
                __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q),
                                       packet->vlan_tci);

        net->stats.rx_packets++;
        net->stats.rx_bytes += packet->total_data_buflen;

        /*
         * Pass the skb back up. Network stack will deallocate the skb when it
         * is done.
         * TODO - use NAPI?
         */
        netif_rx(skb);

        return 0;
}

static void netvsc_get_drvinfo(struct net_device *net,
                               struct ethtool_drvinfo *info)
{
        strlcpy(info->driver, KBUILD_MODNAME, sizeof(info->driver));
        strlcpy(info->fw_version, "N/A", sizeof(info->fw_version));
}

static int netvsc_change_mtu(struct net_device *ndev, int mtu)
{
        struct net_device_context *ndevctx = netdev_priv(ndev);
        struct hv_device *hdev =  ndevctx->device_ctx;
        struct netvsc_device *nvdev = hv_get_drvdata(hdev);
        struct netvsc_device_info device_info;
        int limit = ETH_DATA_LEN;

        if (nvdev == NULL || nvdev->destroy)
                return -ENODEV;

        if (nvdev->nvsp_version == NVSP_PROTOCOL_VERSION_2)
                limit = NETVSC_MTU;

        if (mtu < 68 || mtu > limit)
                return -EINVAL;

        nvdev->start_remove = true;
        cancel_work_sync(&ndevctx->work);
        netif_tx_disable(ndev);
        rndis_filter_device_remove(hdev);

        ndev->mtu = mtu;

        ndevctx->device_ctx = hdev;
        hv_set_drvdata(hdev, ndev);
        device_info.ring_size = ring_size;
        rndis_filter_device_add(hdev, &device_info);
        netif_wake_queue(ndev);

        return 0;
}


static int netvsc_set_mac_addr(struct net_device *ndev, void *p)
{
        struct net_device_context *ndevctx = netdev_priv(ndev);
        struct hv_device *hdev =  ndevctx->device_ctx;
        struct sockaddr *addr = p;
        char save_adr[ETH_ALEN];
        unsigned char save_aatype;
        int err;

        memcpy(save_adr, ndev->dev_addr, ETH_ALEN);
        save_aatype = ndev->addr_assign_type;

        err = eth_mac_addr(ndev, p);
        if (err != 0)
                return err;

        err = rndis_filter_set_device_mac(hdev, addr->sa_data);
        if (err != 0) {
                /* roll back to saved MAC */
                memcpy(ndev->dev_addr, save_adr, ETH_ALEN);
                ndev->addr_assign_type = save_aatype;
        }

        return err;
}


static const struct ethtool_ops ethtool_ops = {
        .get_drvinfo    = netvsc_get_drvinfo,
        .get_link       = ethtool_op_get_link,
};

static const struct net_device_ops device_ops = {
        .ndo_open =                     netvsc_open,
        .ndo_stop =                     netvsc_close,
        .ndo_start_xmit =               netvsc_start_xmit,
        .ndo_set_rx_mode =              netvsc_set_multicast_list,
        .ndo_change_mtu =               netvsc_change_mtu,
        .ndo_validate_addr =            eth_validate_addr,
        .ndo_set_mac_address =          netvsc_set_mac_addr,
};

/*
 * Send GARP packet to network peers after migrations.
 * After Quick Migration, the network is not immediately operational in the
 * current context when receiving RNDIS_STATUS_MEDIA_CONNECT event. So, add
 * another netif_notify_peers() into a delayed work, otherwise GARP packet
 * will not be sent after quick migration, and cause network disconnection.
 */
static void netvsc_send_garp(struct work_struct *w)
{
        struct net_device_context *ndev_ctx;
        struct net_device *net;
        struct netvsc_device *net_device;

        ndev_ctx = container_of(w, struct net_device_context, dwork.work);
        net_device = hv_get_drvdata(ndev_ctx->device_ctx);
        net = net_device->ndev;
        netdev_notify_peers(net);
}


static int netvsc_probe(struct hv_device *dev,
                        const struct hv_vmbus_device_id *dev_id)
{
        struct net_device *net = NULL;
        struct net_device_context *net_device_ctx;
        struct netvsc_device_info device_info;
        int ret;

        net = alloc_etherdev(sizeof(struct net_device_context));
        if (!net)
                return -ENOMEM;

        /* Set initial state */
        netif_carrier_off(net);

        net_device_ctx = netdev_priv(net);
        net_device_ctx->device_ctx = dev;
        hv_set_drvdata(dev, net);
        INIT_DELAYED_WORK(&net_device_ctx->dwork, netvsc_send_garp);
        INIT_WORK(&net_device_ctx->work, do_set_multicast);

        net->netdev_ops = &device_ops;

        /* TODO: Add GSO and Checksum offload */
        net->hw_features = 0;
        net->features = NETIF_F_HW_VLAN_CTAG_TX;

        SET_ETHTOOL_OPS(net, &ethtool_ops);
        SET_NETDEV_DEV(net, &dev->device);

        /* Notify the netvsc driver of the new device */
        device_info.ring_size = ring_size;
        ret = rndis_filter_device_add(dev, &device_info);
        if (ret != 0) {
                netdev_err(net, "unable to add netvsc device (ret %d)\n", ret);
                free_netdev(net);
                hv_set_drvdata(dev, NULL);
                return ret;
        }
        memcpy(net->dev_addr, device_info.mac_adr, ETH_ALEN);

        netif_carrier_on(net);

        ret = register_netdev(net);
        if (ret != 0) {
                pr_err("Unable to register netdev.\n");
                rndis_filter_device_remove(dev);
                free_netdev(net);
        }

        return ret;
}

static int netvsc_remove(struct hv_device *dev)
{
        struct net_device *net;
        struct net_device_context *ndev_ctx;
        struct netvsc_device *net_device;

        net_device = hv_get_drvdata(dev);
        net = net_device->ndev;

        if (net == NULL) {
                dev_err(&dev->device, "No net device to remove\n");
                return 0;
        }

        net_device->start_remove = true;

        ndev_ctx = netdev_priv(net);
        cancel_delayed_work_sync(&ndev_ctx->dwork);
        cancel_work_sync(&ndev_ctx->work);

        /* Stop outbound asap */
        netif_tx_disable(net);

        unregister_netdev(net);

        /*
         * Call to the vsc driver to let it know that the device is being
         * removed
         */
        rndis_filter_device_remove(dev);

        free_netdev(net);
        return 0;
}

static const struct hv_vmbus_device_id id_table[] = {
        /* Network guid */
        { HV_NIC_GUID, },
        { },
};

MODULE_DEVICE_TABLE(vmbus, id_table);

/* The one and only one */
static struct  hv_driver netvsc_drv = {
        .name = KBUILD_MODNAME,
        .id_table = id_table,
        .probe = netvsc_probe,
        .remove = netvsc_remove,
};

static void __exit netvsc_drv_exit(void)
{
        vmbus_driver_unregister(&netvsc_drv);
}

static int __init netvsc_drv_init(void)
{
        if (ring_size < RING_SIZE_MIN) {
                ring_size = RING_SIZE_MIN;
                pr_info("Increased ring_size to %d (min allowed)\n",
                        ring_size);
        }
        return vmbus_driver_register(&netvsc_drv);
}

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Microsoft Hyper-V network driver");

module_init(netvsc_drv_init);
module_exit(netvsc_drv_exit);