/*
 * 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>
 */
#include <linux/init.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/in.h>
#include <net/arp.h>
#include <net/route.h>
#include <net/sock.h>
#include <net/pkt_sched.h>
#include "osd.h"
#include "logging.h"
#include "vmbus.h"
#include "NetVscApi.h"

MODULE_LICENSE("GPL");

struct net_device_context {
        /* point back to our device context */
        struct device_context *device_ctx;
        struct net_device_stats stats;
};

struct netvsc_driver_context {
        /* !! These must be the first 2 fields !! */
        /* Which is a bug FIXME! */
        struct driver_context drv_ctx;
        struct netvsc_driver drv_obj;
};

static int netvsc_ringbuffer_size = NETVSC_DEVICE_RING_BUFFER_SIZE;

/* The one and only one */
static struct netvsc_driver_context g_netvsc_drv;

static struct net_device_stats *netvsc_get_stats(struct net_device *net)
{
        struct net_device_context *net_device_ctx = netdev_priv(net);

        return &net_device_ctx->stats;
}

static void netvsc_set_multicast_list(struct net_device *net)
{
}

static int netvsc_open(struct net_device *net)
{
        struct net_device_context *net_device_ctx = netdev_priv(net);
        struct driver_context *driver_ctx =
            driver_to_driver_context(net_device_ctx->device_ctx->device.driver);
        struct netvsc_driver_context *net_drv_ctx =
                (struct netvsc_driver_context *)driver_ctx;
        struct netvsc_driver *net_drv_obj = &net_drv_ctx->drv_obj;
        struct hv_device *device_obj = &net_device_ctx->device_ctx->device_obj;
        int ret = 0;

        DPRINT_ENTER(NETVSC_DRV);

        if (netif_carrier_ok(net)) {
                memset(&net_device_ctx->stats, 0,
                       sizeof(struct net_device_stats));

                /* Open up the device */
                ret = net_drv_obj->OnOpen(device_obj);
                if (ret != 0) {
                        DPRINT_ERR(NETVSC_DRV,
                                   "unable to open device (ret %d).", ret);
                        return ret;
                }

                netif_start_queue(net);
        } else {
                DPRINT_ERR(NETVSC_DRV, "unable to open device...link is down.");
        }

        DPRINT_EXIT(NETVSC_DRV);
        return ret;
}

static int netvsc_close(struct net_device *net)
{
        struct net_device_context *net_device_ctx = netdev_priv(net);
        struct driver_context *driver_ctx =
            driver_to_driver_context(net_device_ctx->device_ctx->device.driver);
        struct netvsc_driver_context *net_drv_ctx =
                (struct netvsc_driver_context *)driver_ctx;
        struct netvsc_driver *net_drv_obj = &net_drv_ctx->drv_obj;
        struct hv_device *device_obj = &net_device_ctx->device_ctx->device_obj;
        int ret;

        DPRINT_ENTER(NETVSC_DRV);

        netif_stop_queue(net);

        ret = net_drv_obj->OnClose(device_obj);
        if (ret != 0)
                DPRINT_ERR(NETVSC_DRV, "unable to close device (ret %d).", ret);

        DPRINT_EXIT(NETVSC_DRV);

        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.SendCompletionTid;
        struct net_device *net;

        DPRINT_ENTER(NETVSC_DRV);

        kfree(packet);

        if (skb) {
                net = skb->dev;
                dev_kfree_skb_any(skb);

                if (netif_queue_stopped(net)) {
                        DPRINT_INFO(NETVSC_DRV, "net device (%p) waking up...",
                                    net);

                        netif_wake_queue(net);
                }
        }

        DPRINT_EXIT(NETVSC_DRV);
}

static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
{
        struct net_device_context *net_device_ctx = netdev_priv(net);
        struct driver_context *driver_ctx =
            driver_to_driver_context(net_device_ctx->device_ctx->device.driver);
        struct netvsc_driver_context *net_drv_ctx =
                (struct netvsc_driver_context *)driver_ctx;
        struct netvsc_driver *net_drv_obj = &net_drv_ctx->drv_obj;
        struct hv_netvsc_packet *packet;
        int i;
        int ret;
        int num_frags;
        int retries = 0;

        DPRINT_ENTER(NETVSC_DRV);

        /* Support only 1 chain of frags */
        ASSERT(skb_shinfo(skb)->frag_list == NULL);
        ASSERT(skb->dev == net);

        DPRINT_DBG(NETVSC_DRV, "xmit packet - len %d data_len %d",
                   skb->len, skb->data_len);

        /* Add 1 for skb->data and any additional ones requested */
        num_frags = skb_shinfo(skb)->nr_frags + 1 +
                    net_drv_obj->AdditionalRequestPageBufferCount;

        /* Allocate a netvsc packet based on # of frags. */
        packet = kzalloc(sizeof(struct hv_netvsc_packet) +
                         (num_frags * sizeof(struct hv_page_buffer)) +
                         net_drv_obj->RequestExtSize, GFP_ATOMIC);
        if (!packet) {
                DPRINT_ERR(NETVSC_DRV, "unable to allocate hv_netvsc_packet");
                return -1;
        }

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

        /* Setup the rndis header */
        packet->PageBufferCount = num_frags;

        /* TODO: Flush all write buffers/ memory fence ??? */
        /* wmb(); */

        /* Initialize it from the skb */
        ASSERT(skb->data);
        packet->TotalDataBufferLength   = skb->len;

        /*
         * Start filling in the page buffers starting at
         * AdditionalRequestPageBufferCount offset
         */
        packet->PageBuffers[net_drv_obj->AdditionalRequestPageBufferCount].Pfn = virt_to_phys(skb->data) >> PAGE_SHIFT;
        packet->PageBuffers[net_drv_obj->AdditionalRequestPageBufferCount].Offset = (unsigned long)skb->data & (PAGE_SIZE - 1);
        packet->PageBuffers[net_drv_obj->AdditionalRequestPageBufferCount].Length = skb->len - skb->data_len;

        ASSERT((skb->len - skb->data_len) <= PAGE_SIZE);

        for (i = net_drv_obj->AdditionalRequestPageBufferCount + 1;
             i < num_frags; i++) {
                packet->PageBuffers[i].Pfn =
                        page_to_pfn(skb_shinfo(skb)->frags[i-(net_drv_obj->AdditionalRequestPageBufferCount+1)].page);
                packet->PageBuffers[i].Offset =
                        skb_shinfo(skb)->frags[i-(net_drv_obj->AdditionalRequestPageBufferCount+1)].page_offset;
                packet->PageBuffers[i].Length =
                        skb_shinfo(skb)->frags[i-(net_drv_obj->AdditionalRequestPageBufferCount+1)].size;
        }

        /* Set the completion routine */
        packet->Completion.Send.OnSendCompletion = netvsc_xmit_completion;
        packet->Completion.Send.SendCompletionContext = packet;
        packet->Completion.Send.SendCompletionTid = (unsigned long)skb;

retry_send:
        ret = net_drv_obj->OnSend(&net_device_ctx->device_ctx->device_obj,
                                  packet);

        if (ret == 0) {
                ret = NETDEV_TX_OK;
                net_device_ctx->stats.tx_bytes += skb->len;
                net_device_ctx->stats.tx_packets++;
        } else {
                retries++;
                if (retries < 4) {
                        DPRINT_ERR(NETVSC_DRV, "unable to send..."
                                        "retrying %d...", retries);
                        udelay(100);
                        goto retry_send;
                }

                /* no more room or we are shutting down */
                DPRINT_ERR(NETVSC_DRV, "unable to send (%d)..."
                           "marking net device (%p) busy", ret, net);
                DPRINT_INFO(NETVSC_DRV, "net device (%p) stopping", net);

                ret = NETDEV_TX_BUSY;
                net_device_ctx->stats.tx_dropped++;

                netif_stop_queue(net);

                /*
                 * Null it since the caller will free it instead of the
                 * completion routine
                 */
                packet->Completion.Send.SendCompletionTid = 0;

                /*
                 * Release the resources since we will not get any send
                 * completion
                 */
                netvsc_xmit_completion((void *)packet);
        }

        DPRINT_DBG(NETVSC_DRV, "# of xmits %lu total size %lu",
                   net_device_ctx->stats.tx_packets,
                   net_device_ctx->stats.tx_bytes);

        DPRINT_EXIT(NETVSC_DRV);
        return ret;
}

/**
 * netvsc_linkstatus_callback - Link up/down notification
 */
static void netvsc_linkstatus_callback(struct hv_device *device_obj,
                                       unsigned int status)
{
        struct device_context *device_ctx = to_device_context(device_obj);
        struct net_device *net = dev_get_drvdata(&device_ctx->device);

        DPRINT_ENTER(NETVSC_DRV);

        if (!net) {
                DPRINT_ERR(NETVSC_DRV, "got link status but net device "
                                "not initialized yet");
                return;
        }

        if (status == 1) {
                netif_carrier_on(net);
                netif_wake_queue(net);
        } else {
                netif_carrier_off(net);
                netif_stop_queue(net);
        }
        DPRINT_EXIT(NETVSC_DRV);
}

/**
 * netvsc_recv_callback -  Callback when we receive a packet from the "wire" on the specified device.
 */
static int netvsc_recv_callback(struct hv_device *device_obj,
                                struct hv_netvsc_packet *packet)
{
        struct device_context *device_ctx = to_device_context(device_obj);
        struct net_device *net = dev_get_drvdata(&device_ctx->device);
        struct net_device_context *net_device_ctx;
        struct sk_buff *skb;
        void *data;
        int ret;
        int i;
        unsigned long flags;

        DPRINT_ENTER(NETVSC_DRV);

        if (!net) {
                DPRINT_ERR(NETVSC_DRV, "got receive callback but net device "
                                "not initialized yet");
                return 0;
        }

        net_device_ctx = netdev_priv(net);

        /* Allocate a skb - TODO preallocate this */
        /* Pad 2-bytes to align IP header to 16 bytes */
        skb = dev_alloc_skb(packet->TotalDataBufferLength + 2);
        ASSERT(skb);
        skb_reserve(skb, 2);
        skb->dev = net;

        /* for kmap_atomic */
        local_irq_save(flags);

        /*
         * Copy to skb. This copy is needed here since the memory pointed by
         * hv_netvsc_packet cannot be deallocated
         */
        for (i = 0; i < packet->PageBufferCount; i++) {
                data = kmap_atomic(pfn_to_page(packet->PageBuffers[i].Pfn),
                                               KM_IRQ1);
                data = (void *)(unsigned long)data +
                                packet->PageBuffers[i].Offset;

                memcpy(skb_put(skb, packet->PageBuffers[i].Length), data,
                       packet->PageBuffers[i].Length);

                kunmap_atomic((void *)((unsigned long)data -
                                       packet->PageBuffers[i].Offset), KM_IRQ1);
        }

        local_irq_restore(flags);

        skb->protocol = eth_type_trans(skb, net);

        skb->ip_summed = CHECKSUM_NONE;

        /*
         * Pass the skb back up. Network stack will deallocate the skb when it
         * is done
         */
        ret = netif_rx(skb);

        switch (ret) {
        case NET_RX_DROP:
                net_device_ctx->stats.rx_dropped++;
                break;
        default:
                net_device_ctx->stats.rx_packets++;
                net_device_ctx->stats.rx_bytes += skb->len;
                break;

        }
        DPRINT_DBG(NETVSC_DRV, "# of recvs %lu total size %lu",
                   net_device_ctx->stats.rx_packets,
                   net_device_ctx->stats.rx_bytes);

        DPRINT_EXIT(NETVSC_DRV);

        return 0;
}

static const struct net_device_ops device_ops = {
        .ndo_open =                     netvsc_open,
        .ndo_stop =                     netvsc_close,
        .ndo_start_xmit =               netvsc_start_xmit,
        .ndo_get_stats =                netvsc_get_stats,
        .ndo_set_multicast_list =       netvsc_set_multicast_list,
};

static int netvsc_probe(struct device *device)
{
        struct driver_context *driver_ctx =
                driver_to_driver_context(device->driver);
        struct netvsc_driver_context *net_drv_ctx =
                (struct netvsc_driver_context *)driver_ctx;
        struct netvsc_driver *net_drv_obj = &net_drv_ctx->drv_obj;
        struct device_context *device_ctx = device_to_device_context(device);
        struct hv_device *device_obj = &device_ctx->device_obj;
        struct net_device *net = NULL;
        struct net_device_context *net_device_ctx;
        struct netvsc_device_info device_info;
        int ret;

        DPRINT_ENTER(NETVSC_DRV);

        if (!net_drv_obj->Base.OnDeviceAdd)
                return -1;

        net = alloc_netdev(sizeof(struct net_device_context), "seth%d",
                           ether_setup);
        if (!net)
                return -1;

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

        net_device_ctx = netdev_priv(net);
        net_device_ctx->device_ctx = device_ctx;
        dev_set_drvdata(device, net);

        /* Notify the netvsc driver of the new device */
        ret = net_drv_obj->Base.OnDeviceAdd(device_obj, &device_info);
        if (ret != 0) {
                free_netdev(net);
                dev_set_drvdata(device, NULL);

                DPRINT_ERR(NETVSC_DRV, "unable to add netvsc device (ret %d)",
                           ret);
                return ret;
        }

        /*
         * If carrier is still off ie we did not get a link status callback,
         * update it if necessary
         */
        /*
         * FIXME: We should use a atomic or test/set instead to avoid getting
         * out of sync with the device's link status
         */
        if (!netif_carrier_ok(net))
                if (!device_info.LinkState)
                        netif_carrier_on(net);

        memcpy(net->dev_addr, device_info.MacAddr, ETH_ALEN);

        net->netdev_ops = &device_ops;

        SET_NETDEV_DEV(net, device);

        ret = register_netdev(net);
        if (ret != 0) {
                /* Remove the device and release the resource */
                net_drv_obj->Base.OnDeviceRemove(device_obj);
                free_netdev(net);
        }

        DPRINT_EXIT(NETVSC_DRV);
        return ret;
}

static int netvsc_remove(struct device *device)
{
        struct driver_context *driver_ctx =
                driver_to_driver_context(device->driver);
        struct netvsc_driver_context *net_drv_ctx =
                (struct netvsc_driver_context *)driver_ctx;
        struct netvsc_driver *net_drv_obj = &net_drv_ctx->drv_obj;
        struct device_context *device_ctx = device_to_device_context(device);
        struct net_device *net = dev_get_drvdata(&device_ctx->device);
        struct hv_device *device_obj = &device_ctx->device_obj;
        int ret;

        DPRINT_ENTER(NETVSC_DRV);

        if (net == NULL) {
                DPRINT_INFO(NETVSC, "no net device to remove");
                DPRINT_EXIT(NETVSC_DRV);
                return 0;
        }

        if (!net_drv_obj->Base.OnDeviceRemove) {
                DPRINT_EXIT(NETVSC_DRV);
                return -1;
        }

        /* Stop outbound asap */
        netif_stop_queue(net);
        /* netif_carrier_off(net); */

        unregister_netdev(net);

        /*
         * Call to the vsc driver to let it know that the device is being
         * removed
         */
        ret = net_drv_obj->Base.OnDeviceRemove(device_obj);
        if (ret != 0) {
                /* TODO: */
                DPRINT_ERR(NETVSC, "unable to remove vsc device (ret %d)", ret);
        }

        free_netdev(net);
        DPRINT_EXIT(NETVSC_DRV);
        return ret;
}

static int netvsc_drv_exit_cb(struct device *dev, void *data)
{
        struct device **curr = (struct device **)data;

        *curr = dev;
        /* stop iterating */
        return 1;
}

static void netvsc_drv_exit(void)
{
        struct netvsc_driver *netvsc_drv_obj = &g_netvsc_drv.drv_obj;
        struct driver_context *drv_ctx = &g_netvsc_drv.drv_ctx;
        struct device *current_dev;
        int ret;

        DPRINT_ENTER(NETVSC_DRV);

        while (1) {
                current_dev = NULL;

                /* Get the device */
                ret = driver_for_each_device(&drv_ctx->driver, NULL,
                                             &current_dev, netvsc_drv_exit_cb);
                if (ret)
                        DPRINT_WARN(NETVSC_DRV,
                                    "driver_for_each_device returned %d", ret);

                if (current_dev == NULL)
                        break;

                /* Initiate removal from the top-down */
                DPRINT_INFO(NETVSC_DRV, "unregistering device (%p)...",
                            current_dev);

                device_unregister(current_dev);
        }

        if (netvsc_drv_obj->Base.OnCleanup)
                netvsc_drv_obj->Base.OnCleanup(&netvsc_drv_obj->Base);

        vmbus_child_driver_unregister(drv_ctx);

        DPRINT_EXIT(NETVSC_DRV);

        return;
}

static int netvsc_drv_init(int (*drv_init)(struct hv_driver *drv))
{
        struct netvsc_driver *net_drv_obj = &g_netvsc_drv.drv_obj;
        struct driver_context *drv_ctx = &g_netvsc_drv.drv_ctx;
        int ret;

        DPRINT_ENTER(NETVSC_DRV);

        vmbus_get_interface(&net_drv_obj->Base.VmbusChannelInterface);

        net_drv_obj->RingBufferSize = netvsc_ringbuffer_size;
        net_drv_obj->OnReceiveCallback = netvsc_recv_callback;
        net_drv_obj->OnLinkStatusChanged = netvsc_linkstatus_callback;

        /* Callback to client driver to complete the initialization */
        drv_init(&net_drv_obj->Base);

        drv_ctx->driver.name = net_drv_obj->Base.name;
        memcpy(&drv_ctx->class_id, &net_drv_obj->Base.deviceType,
               sizeof(struct hv_guid));

        drv_ctx->probe = netvsc_probe;
        drv_ctx->remove = netvsc_remove;

        /* The driver belongs to vmbus */
        ret = vmbus_child_driver_register(drv_ctx);

        DPRINT_EXIT(NETVSC_DRV);

        return ret;
}

static int __init netvsc_init(void)
{
        int ret;

        DPRINT_ENTER(NETVSC_DRV);
        DPRINT_INFO(NETVSC_DRV, "Netvsc initializing....");

        ret = netvsc_drv_init(NetVscInitialize);

        DPRINT_EXIT(NETVSC_DRV);

        return ret;
}

static void __exit netvsc_exit(void)
{
        DPRINT_ENTER(NETVSC_DRV);
        netvsc_drv_exit();
        DPRINT_EXIT(NETVSC_DRV);
}

module_param(netvsc_ringbuffer_size, int, S_IRUGO);

module_init(netvsc_init);
module_exit(netvsc_exit);