[mirror_ubuntu-bionic-kernel.git] / drivers / staging / unisys / visornic / visornic_main.c

/* Copyright (c) 2012 - 2015 UNISYS CORPORATION
 * All rights reserved.
 *
 * 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 that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 * NON INFRINGEMENT.  See the GNU General Public License for more
 * details.
 */

/* This driver lives in a spar partition, and registers to ethernet io
 * channels from the visorbus driver. It creates netdev devices and
 * forwards transmit to the IO channel and accepts rcvs from the IO
 * Partition via the IO channel.
 */

#include <linux/debugfs.h>
#include <linux/etherdevice.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/kthread.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>

#include "visorbus.h"
#include "iochannel.h"

#define VISORNIC_INFINITE_RSP_WAIT 0

/* MAX_BUF = 64 lines x 32 MAXVNIC x 80 characters
 *         = 163840 bytes
 */
#define MAX_BUF 163840
#define NAPI_WEIGHT 64

/* GUIDS for director channel type supported by this driver.  */
/* {8cd5994d-c58e-11da-95a9-00e08161165f} */
#define VISOR_VNIC_CHANNEL_GUID \
        GUID_INIT(0x8cd5994d, 0xc58e, 0x11da, \
                0x95, 0xa9, 0x0, 0xe0, 0x81, 0x61, 0x16, 0x5f)
#define VISOR_VNIC_CHANNEL_GUID_STR \
        "8cd5994d-c58e-11da-95a9-00e08161165f"

static struct visor_channeltype_descriptor visornic_channel_types[] = {
        /* Note that the only channel type we expect to be reported by the
         * bus driver is the VISOR_VNIC channel.
         */
        { VISOR_VNIC_CHANNEL_GUID, "ultravnic", sizeof(struct channel_header),
          VISOR_VNIC_CHANNEL_VERSIONID },
        {}
};
MODULE_DEVICE_TABLE(visorbus, visornic_channel_types);
/* FIXME XXX: This next line of code must be fixed and removed before
 * acceptance into the 'normal' part of the kernel.  It is only here as a place
 * holder to get module autoloading functionality working for visorbus.  Code
 * must be added to scripts/mode/file2alias.c, etc., to get this working
 * properly.
 */
MODULE_ALIAS("visorbus:" VISOR_VNIC_CHANNEL_GUID_STR);

struct chanstat {
        unsigned long got_rcv;
        unsigned long got_enbdisack;
        unsigned long got_xmit_done;
        unsigned long xmit_fail;
        unsigned long sent_enbdis;
        unsigned long sent_promisc;
        unsigned long sent_post;
        unsigned long sent_post_failed;
        unsigned long sent_xmit;
        unsigned long reject_count;
        unsigned long extra_rcvbufs_sent;
};

/* struct visornic_devdata
 * @enabled:                        0 disabled 1 enabled to receive.
 * @enab_dis_acked:                 NET_RCV_ENABLE/DISABLE acked by IOPART.
 * @struct *dev:
 * @struct *netdev:
 * @struct net_stats:
 * @interrupt_rcvd:
 * @rsp_queue:
 * @struct **rcvbuf:
 * @incarnation_id:                 incarnation_id lets IOPART know about
 *                                  re-birth.
 * @old_flags:                      flags as they were prior to
 *                                  set_multicast_list.
 * @usage:                          count of users.
 * @num_rcv_bufs:                   number of rcv buffers the vnic will post.
 * @num_rcv_bufs_could_not_alloc:
 * @num_rcvbuf_in_iovm:
 * @alloc_failed_in_if_needed_cnt:
 * @alloc_failed_in_repost_rtn_cnt:
 * @max_outstanding_net_xmits:      absolute max number of outstanding xmits
 *                                  - should never hit this.
 * @upper_threshold_net_xmits:      high water mark for calling
 *                                  netif_stop_queue().
 * @lower_threshold_net_xmits:      high water mark for calling
 *                                  netif_wake_queue().
 * @struct xmitbufhead:             xmitbufhead - head of the xmit buffer list
 *                                  sent to the IOPART end.
 * @server_down_complete_func:
 * @struct timeout_reset:
 * @struct *cmdrsp_rcv:             cmdrsp_rcv is used for posting/unposting rcv
 *                                  buffers.
 * @struct *xmit_cmdrsp:            xmit_cmdrsp - issues NET_XMIT - only one
 *                                  active xmit at a time.
 * @server_down:                    IOPART is down.
 * @server_change_state:            Processing SERVER_CHANGESTATE msg.
 * @going_away:                     device is being torn down.
 * @struct *eth_debugfs_dir:
 * @interrupts_rcvd:
 * @interrupts_notme:
 * @interrupts_disabled:
 * @busy_cnt:
 * @priv_lock:                      spinlock to access devdata structures.
 * @flow_control_upper_hits:
 * @flow_control_lower_hits:
 * @n_rcv0:                         # rcvs of 0 buffers.
 * @n_rcv1:                         # rcvs of 1 buffers.
 * @n_rcv2:                         # rcvs of 2 buffers.
 * @n_rcvx:                         # rcvs of >2 buffers.
 * @found_repost_rcvbuf_cnt:        # repost_rcvbuf_cnt.
 * @repost_found_skb_cnt:           # of found the skb.
 * @n_repost_deficit:               # of lost rcv buffers.
 * @bad_rcv_buf:                    # of unknown rcv skb not freed.
 * @n_rcv_packets_not_accepted:     # bogs rcv packets.
 * @queuefullmsg_logged:
 * @struct chstat:
 * @struct irq_poll_timer:
 * @struct napi:
 * @struct cmdrsp:
 */
struct visornic_devdata {
        unsigned short enabled;
        unsigned short enab_dis_acked;

        struct visor_device *dev;
        struct net_device *netdev;
        struct net_device_stats net_stats;
        atomic_t interrupt_rcvd;
        wait_queue_head_t rsp_queue;
        struct sk_buff **rcvbuf;
        u64 incarnation_id;
        unsigned short old_flags;
        atomic_t usage;

        int num_rcv_bufs;
        int num_rcv_bufs_could_not_alloc;
        atomic_t num_rcvbuf_in_iovm;
        unsigned long alloc_failed_in_if_needed_cnt;
        unsigned long alloc_failed_in_repost_rtn_cnt;

        unsigned long max_outstanding_net_xmits;
        unsigned long upper_threshold_net_xmits;
        unsigned long lower_threshold_net_xmits;
        struct sk_buff_head xmitbufhead;

        visorbus_state_complete_func server_down_complete_func;
        struct work_struct timeout_reset;
        struct uiscmdrsp *cmdrsp_rcv;
        struct uiscmdrsp *xmit_cmdrsp;
        bool server_down;
        bool server_change_state;
        bool going_away;
        struct dentry *eth_debugfs_dir;
        u64 interrupts_rcvd;
        u64 interrupts_notme;
        u64 interrupts_disabled;
        u64 busy_cnt;
        /* spinlock to access devdata structures. */
        spinlock_t priv_lock;

        /* flow control counter */
        u64 flow_control_upper_hits;
        u64 flow_control_lower_hits;

        /* debug counters */
        unsigned long n_rcv0;
        unsigned long n_rcv1;
        unsigned long n_rcv2;
        unsigned long n_rcvx;
        unsigned long found_repost_rcvbuf_cnt;
        unsigned long repost_found_skb_cnt;
        unsigned long n_repost_deficit;
        unsigned long bad_rcv_buf;
        unsigned long n_rcv_packets_not_accepted;

        int queuefullmsg_logged;
        struct chanstat chstat;
        struct timer_list irq_poll_timer;
        struct napi_struct napi;
        struct uiscmdrsp cmdrsp[SIZEOF_CMDRSP];
};

/* Returns next non-zero index on success or 0 on failure (i.e. out of room). */
static u16 add_physinfo_entries(u64 inp_pfn, u16 inp_off, u16 inp_len,
                                u16 index, u16 max_pi_arr_entries,
                                struct phys_info pi_arr[])
{
        u16 i, len, firstlen;

        firstlen = PI_PAGE_SIZE - inp_off;
        if (inp_len <= firstlen) {
                /* The input entry spans only one page - add as is. */
                if (index >= max_pi_arr_entries)
                        return 0;
                pi_arr[index].pi_pfn = inp_pfn;
                pi_arr[index].pi_off = (u16)inp_off;
                pi_arr[index].pi_len = (u16)inp_len;
                return index + 1;
        }

        /* This entry spans multiple pages. */
        for (len = inp_len, i = 0; len;
                len -= pi_arr[index + i].pi_len, i++) {
                if (index + i >= max_pi_arr_entries)
                        return 0;
                pi_arr[index + i].pi_pfn = inp_pfn + i;
                if (i == 0) {
                        pi_arr[index].pi_off = inp_off;
                        pi_arr[index].pi_len = firstlen;
                } else {
                        pi_arr[index + i].pi_off = 0;
                        pi_arr[index + i].pi_len = min_t(u16, len,
                                                         PI_PAGE_SIZE);
                }
        }
        return index + i;
}

/* visor_copy_fragsinfo_from_skb - copy fragment list in the SKB to a phys_info
 *                                 array that the IOPART understands
 * @skb:          Skbuff that we are pulling the frags from.
 * @firstfraglen: Length of first fragment in skb.
 * @frags_max:    Max len of frags array.
 * @frags:        Frags array filled in on output.
 *
 * Return: Positive integer indicating number of entries filled in frags on
 *         success, negative integer on error.
 */
static int visor_copy_fragsinfo_from_skb(struct sk_buff *skb,
                                         unsigned int firstfraglen,
                                         unsigned int frags_max,
                                         struct phys_info frags[])
{
        unsigned int count = 0, frag, size, offset = 0, numfrags;
        unsigned int total_count;

        numfrags = skb_shinfo(skb)->nr_frags;

        /* Compute the number of fragments this skb has, and if its more than
         * frag array can hold, linearize the skb
         */
        total_count = numfrags + (firstfraglen / PI_PAGE_SIZE);
        if (firstfraglen % PI_PAGE_SIZE)
                total_count++;

        if (total_count > frags_max) {
                if (skb_linearize(skb))
                        return -EINVAL;
                numfrags = skb_shinfo(skb)->nr_frags;
                firstfraglen = 0;
        }

        while (firstfraglen) {
                if (count == frags_max)
                        return -EINVAL;

                frags[count].pi_pfn =
                        page_to_pfn(virt_to_page(skb->data + offset));
                frags[count].pi_off =
                        (unsigned long)(skb->data + offset) & PI_PAGE_MASK;
                size = min_t(unsigned int, firstfraglen,
                             PI_PAGE_SIZE - frags[count].pi_off);

                /* can take smallest of firstfraglen (what's left) OR
                 * bytes left in the page
                 */
                frags[count].pi_len = size;
                firstfraglen -= size;
                offset += size;
                count++;
        }
        if (numfrags) {
                if ((count + numfrags) > frags_max)
                        return -EINVAL;

                for (frag = 0; frag < numfrags; frag++) {
                        count = add_physinfo_entries(page_to_pfn(
                                  skb_frag_page(&skb_shinfo(skb)->frags[frag])),
                                  skb_shinfo(skb)->frags[frag].page_offset,
                                  skb_shinfo(skb)->frags[frag].size, count,
                                  frags_max, frags);
                        /* add_physinfo_entries only returns
                         * zero if the frags array is out of room
                         * That should never happen because we
                         * fail above, if count+numfrags > frags_max.
                         */
                        if (!count)
                                return -EINVAL;
                }
        }
        if (skb_shinfo(skb)->frag_list) {
                struct sk_buff *skbinlist;
                int c;

                for (skbinlist = skb_shinfo(skb)->frag_list; skbinlist;
                     skbinlist = skbinlist->next) {
                        c = visor_copy_fragsinfo_from_skb(skbinlist,
                                                          skbinlist->len -
                                                          skbinlist->data_len,
                                                          frags_max - count,
                                                          &frags[count]);
                        if (c < 0)
                                return c;
                        count += c;
                }
        }
        return count;
}

static ssize_t enable_ints_write(struct file *file,
                                 const char __user *buffer,
                                 size_t count, loff_t *ppos)
{
        /* Don't want to break ABI here by having a debugfs
         * file that no longer exists or is writable, so
         * lets just make this a vestigual function
         */
        return count;
}

static const struct file_operations debugfs_enable_ints_fops = {
        .write = enable_ints_write,
};

/* visornic_serverdown_complete - pause device following IOPART going down
 * @devdata: Device managed by IOPART.
 *
 * The IO partition has gone down, and we need to do some cleanup for when it
 * comes back. Treat the IO partition as the link being down.
 */
static void visornic_serverdown_complete(struct visornic_devdata *devdata)
{
        struct net_device *netdev = devdata->netdev;

        /* Stop polling for interrupts */
        del_timer_sync(&devdata->irq_poll_timer);

        rtnl_lock();
        dev_close(netdev);
        rtnl_unlock();

        atomic_set(&devdata->num_rcvbuf_in_iovm, 0);
        devdata->chstat.sent_xmit = 0;
        devdata->chstat.got_xmit_done = 0;

        if (devdata->server_down_complete_func)
                (*devdata->server_down_complete_func)(devdata->dev, 0);

        devdata->server_down = true;
        devdata->server_change_state = false;
        devdata->server_down_complete_func = NULL;
}

/* visornic_serverdown - Command has notified us that IOPART is down
 * @devdata:       Device managed by IOPART.
 * @complete_func: Function to call when finished.
 *
 * Schedule the work needed to handle the server down request. Make sure we
 * haven't already handled the server change state event.
 *
 * Return: 0 if we scheduled the work, negative integer on error.
 */
static int visornic_serverdown(struct visornic_devdata *devdata,
                               visorbus_state_complete_func complete_func)
{
        unsigned long flags;
        int err;

        spin_lock_irqsave(&devdata->priv_lock, flags);
        if (devdata->server_change_state) {
                dev_dbg(&devdata->dev->device, "%s changing state\n",
                        __func__);
                err = -EINVAL;
                goto err_unlock;
        }
        if (devdata->server_down) {
                dev_dbg(&devdata->dev->device, "%s already down\n",
                        __func__);
                err = -EINVAL;
                goto err_unlock;
        }
        if (devdata->going_away) {
                dev_dbg(&devdata->dev->device,
                        "%s aborting because device removal pending\n",
                        __func__);
                err = -ENODEV;
                goto err_unlock;
        }
        devdata->server_change_state = true;
        devdata->server_down_complete_func = complete_func;
        spin_unlock_irqrestore(&devdata->priv_lock, flags);

        visornic_serverdown_complete(devdata);
        return 0;

err_unlock:
        spin_unlock_irqrestore(&devdata->priv_lock, flags);
        return err;
}

/* alloc_rcv_buf - alloc rcv buffer to be given to the IO Partition
 * @netdev: Network adapter the rcv bufs are attached too.
 *
 * Create an sk_buff (rcv_buf) that will be passed to the IO Partition
 * so that it can write rcv data into our memory space.
 *
 * Return: Pointer to sk_buff.
 */
static struct sk_buff *alloc_rcv_buf(struct net_device *netdev)
{
        struct sk_buff *skb;

        /* NOTE: the first fragment in each rcv buffer is pointed to by
         * rcvskb->data. For now all rcv buffers will be RCVPOST_BUF_SIZE
         * in length, so the first frag is large enough to hold 1514.
         */
        skb = alloc_skb(RCVPOST_BUF_SIZE, GFP_ATOMIC);
        if (!skb)
                return NULL;
        skb->dev = netdev;
        /* current value of mtu doesn't come into play here; large
         * packets will just end up using multiple rcv buffers all of
         * same size.
         */
        skb->len = RCVPOST_BUF_SIZE;
        /* alloc_skb already zeroes it out for clarification. */
        skb->data_len = 0;
        return skb;
}

/* post_skb - post a skb to the IO Partition
 * @cmdrsp:  Cmdrsp packet to be send to the IO Partition.
 * @devdata: visornic_devdata to post the skb to.
 * @skb:     Skb to give to the IO partition.
 *
 * Return: 0 on success, negative integer on error.
 */
static int post_skb(struct uiscmdrsp *cmdrsp, struct visornic_devdata *devdata,
                    struct sk_buff *skb)
{
        int err;

        cmdrsp->net.buf = skb;
        cmdrsp->net.rcvpost.frag.pi_pfn = page_to_pfn(virt_to_page(skb->data));
        cmdrsp->net.rcvpost.frag.pi_off =
                (unsigned long)skb->data & PI_PAGE_MASK;
        cmdrsp->net.rcvpost.frag.pi_len = skb->len;
        cmdrsp->net.rcvpost.unique_num = devdata->incarnation_id;

        if ((cmdrsp->net.rcvpost.frag.pi_off + skb->len) > PI_PAGE_SIZE)
                return -EINVAL;

        cmdrsp->net.type = NET_RCV_POST;
        cmdrsp->cmdtype = CMD_NET_TYPE;
        err = visorchannel_signalinsert(devdata->dev->visorchannel,
                                        IOCHAN_TO_IOPART,
                                        cmdrsp);
        if (err) {
                devdata->chstat.sent_post_failed++;
                return err;
        }

        atomic_inc(&devdata->num_rcvbuf_in_iovm);
        devdata->chstat.sent_post++;
        return 0;
}

/* send_enbdis - Send NET_RCV_ENBDIS to IO Partition
 * @netdev:  Netdevice we are enabling/disabling, used as context return value.
 * @state:   Enable = 1/disable = 0.
 * @devdata: Visornic device we are enabling/disabling.
 *
 * Send the enable/disable message to the IO Partition.
 *
 * Return: 0 on success, negative integer on error.
 */
static int send_enbdis(struct net_device *netdev, int state,
                       struct visornic_devdata *devdata)
{
        int err;

        devdata->cmdrsp_rcv->net.enbdis.enable = state;
        devdata->cmdrsp_rcv->net.enbdis.context = netdev;
        devdata->cmdrsp_rcv->net.type = NET_RCV_ENBDIS;
        devdata->cmdrsp_rcv->cmdtype = CMD_NET_TYPE;
        err = visorchannel_signalinsert(devdata->dev->visorchannel,
                                        IOCHAN_TO_IOPART,
                                        devdata->cmdrsp_rcv);
        if (err)
                return err;
        devdata->chstat.sent_enbdis++;
        return 0;
}

/* visornic_disable_with_timeout - disable network adapter
 * @netdev:  netdevice to disable.
 * @timeout: Timeout to wait for disable.
 *
 * Disable the network adapter and inform the IO Partition that we are disabled.
 * Reclaim memory from rcv bufs.
 *
 * Return: 0 on success, negative integer on failure of IO Partition responding.
 */
static int visornic_disable_with_timeout(struct net_device *netdev,
                                         const int timeout)
{
        struct visornic_devdata *devdata = netdev_priv(netdev);
        int i;
        unsigned long flags;
        int wait = 0;
        int err;

        /* send a msg telling the other end we are stopping incoming pkts */
        spin_lock_irqsave(&devdata->priv_lock, flags);
        devdata->enabled = 0;
        /* must wait for ack */
        devdata->enab_dis_acked = 0;
        spin_unlock_irqrestore(&devdata->priv_lock, flags);

        /* send disable and wait for ack -- don't hold lock when sending
         * disable because if the queue is full, insert might sleep.
         * If an error occurs, don't wait for the timeout.
         */
        err = send_enbdis(netdev, 0, devdata);
        if (err)
                return err;

        /* wait for ack to arrive before we try to free rcv buffers
         * NOTE: the other end automatically unposts the rcv buffers when
         * when it gets a disable.
         */
        spin_lock_irqsave(&devdata->priv_lock, flags);
        while ((timeout == VISORNIC_INFINITE_RSP_WAIT) ||
               (wait < timeout)) {
                if (devdata->enab_dis_acked)
                        break;
                if (devdata->server_down || devdata->server_change_state) {
                        dev_dbg(&netdev->dev, "%s server went away\n",
                                __func__);
                        break;
                }
                set_current_state(TASK_INTERRUPTIBLE);
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                wait += schedule_timeout(msecs_to_jiffies(10));
                spin_lock_irqsave(&devdata->priv_lock, flags);
        }

        /* Wait for usage to go to 1 (no other users) before freeing
         * rcv buffers
         */
        if (atomic_read(&devdata->usage) > 1) {
                while (1) {
                        set_current_state(TASK_INTERRUPTIBLE);
                        spin_unlock_irqrestore(&devdata->priv_lock, flags);
                        schedule_timeout(msecs_to_jiffies(10));
                        spin_lock_irqsave(&devdata->priv_lock, flags);
                        if (atomic_read(&devdata->usage))
                                break;
                }
        }
        /* we've set enabled to 0, so we can give up the lock. */
        spin_unlock_irqrestore(&devdata->priv_lock, flags);

        /* stop the transmit queue so nothing more can be transmitted */
        netif_stop_queue(netdev);

        napi_disable(&devdata->napi);

        skb_queue_purge(&devdata->xmitbufhead);

        /* Free rcv buffers - other end has automatically unposed them on
         * disable
         */
        for (i = 0; i < devdata->num_rcv_bufs; i++) {
                if (devdata->rcvbuf[i]) {
                        kfree_skb(devdata->rcvbuf[i]);
                        devdata->rcvbuf[i] = NULL;
                }
        }

        return 0;
}

/* init_rcv_bufs - initialize receive buffs and send them to the IO Partition
 * @netdev:  struct netdevice.
 * @devdata: visornic_devdata.
 *
 * Allocate rcv buffers and post them to the IO Partition.
 *
 * Return: 0 on success, negative integer on failure.
 */
static int init_rcv_bufs(struct net_device *netdev,
                         struct visornic_devdata *devdata)
{
        int i, j, count, err;

        /* allocate fixed number of receive buffers to post to uisnic
         * post receive buffers after we've allocated a required amount
         */
        for (i = 0; i < devdata->num_rcv_bufs; i++) {
                devdata->rcvbuf[i] = alloc_rcv_buf(netdev);
                /* if we failed to allocate one let us stop */
                if (!devdata->rcvbuf[i])
                        break;
        }
        /* couldn't even allocate one -- bail out */
        if (i == 0)
                return -ENOMEM;
        count = i;

        /* Ensure we can alloc 2/3rd of the requested number of buffers.
         * 2/3 is an arbitrary choice; used also in ndis init.c
         */
        if (count < ((2 * devdata->num_rcv_bufs) / 3)) {
                /* free receive buffers we did alloc and then bail out */
                for (i = 0; i < count; i++) {
                        kfree_skb(devdata->rcvbuf[i]);
                        devdata->rcvbuf[i] = NULL;
                }
                return -ENOMEM;
        }

        /* post receive buffers to receive incoming input - without holding
         * lock - we've not enabled nor started the queue so there shouldn't
         * be any rcv or xmit activity
         */
        for (i = 0; i < count; i++) {
                err = post_skb(devdata->cmdrsp_rcv, devdata,
                               devdata->rcvbuf[i]);
                if (!err)
                        continue;

                /* Error handling -
                 * If we posted at least one skb, we should return success,
                 * but need to free the resources that we have not successfully
                 * posted.
                 */
                for (j = i; j < count; j++) {
                        kfree_skb(devdata->rcvbuf[j]);
                        devdata->rcvbuf[j] = NULL;
                }
                if (i == 0)
                        return err;
                break;
        }

        return 0;
}

/* visornic_enable_with_timeout - send enable to IO Partition
 * @netdev:  struct net_device.
 * @timeout: Time to wait for the ACK from the enable.
 *
 * Sends enable to IOVM and inits, and posts receive buffers to IOVM. Timeout is
 * defined in msecs (timeout of 0 specifies infinite wait).
 *
 * Return: 0 on success, negative integer on failure.
 */
static int visornic_enable_with_timeout(struct net_device *netdev,
                                        const int timeout)
{
        int err = 0;
        struct visornic_devdata *devdata = netdev_priv(netdev);
        unsigned long flags;
        int wait = 0;

        napi_enable(&devdata->napi);

        /* NOTE: the other end automatically unposts the rcv buffers when it
         * gets a disable.
         */
        err = init_rcv_bufs(netdev, devdata);
        if (err < 0) {
                dev_err(&netdev->dev,
                        "%s failed to init rcv bufs\n", __func__);
                return err;
        }

        spin_lock_irqsave(&devdata->priv_lock, flags);
        devdata->enabled = 1;
        devdata->enab_dis_acked = 0;

        /* now we're ready, let's send an ENB to uisnic but until we get
         * an ACK back from uisnic, we'll drop the packets
         */
        devdata->n_rcv_packets_not_accepted = 0;
        spin_unlock_irqrestore(&devdata->priv_lock, flags);

        /* send enable and wait for ack -- don't hold lock when sending enable
         * because if the queue is full, insert might sleep. If an error
         * occurs error out.
         */
        err = send_enbdis(netdev, 1, devdata);
        if (err)
                return err;

        spin_lock_irqsave(&devdata->priv_lock, flags);
        while ((timeout == VISORNIC_INFINITE_RSP_WAIT) ||
               (wait < timeout)) {
                if (devdata->enab_dis_acked)
                        break;
                if (devdata->server_down || devdata->server_change_state) {
                        dev_dbg(&netdev->dev, "%s server went away\n",
                                __func__);
                        break;
                }
                set_current_state(TASK_INTERRUPTIBLE);
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                wait += schedule_timeout(msecs_to_jiffies(10));
                spin_lock_irqsave(&devdata->priv_lock, flags);
        }

        spin_unlock_irqrestore(&devdata->priv_lock, flags);

        if (!devdata->enab_dis_acked) {
                dev_err(&netdev->dev, "%s missing ACK\n", __func__);
                return -EIO;
        }

        netif_start_queue(netdev);
        return 0;
}

/* visornic_timeout_reset - handle xmit timeout resets
 * @work: Work item that scheduled the work.
 *
 * Transmit timeouts are typically handled by resetting the device for our
 * virtual NIC; we will send a disable and enable to the IOVM. If it doesn't
 * respond, we will trigger a serverdown.
 */
static void visornic_timeout_reset(struct work_struct *work)
{
        struct visornic_devdata *devdata;
        struct net_device *netdev;
        int response = 0;

        devdata = container_of(work, struct visornic_devdata, timeout_reset);
        netdev = devdata->netdev;

        rtnl_lock();
        if (!netif_running(netdev)) {
                rtnl_unlock();
                return;
        }

        response = visornic_disable_with_timeout(netdev,
                                                 VISORNIC_INFINITE_RSP_WAIT);
        if (response)
                goto call_serverdown;

        response = visornic_enable_with_timeout(netdev,
                                                VISORNIC_INFINITE_RSP_WAIT);
        if (response)
                goto call_serverdown;

        rtnl_unlock();

        return;

call_serverdown:
        visornic_serverdown(devdata, NULL);
        rtnl_unlock();
}

/* visornic_open - enable the visornic device and mark the queue started
 * @netdev: netdevice to start.
 *
 * Enable the device and start the transmit queue.
 *
 * Return: 0 on success.
 */
static int visornic_open(struct net_device *netdev)
{
        visornic_enable_with_timeout(netdev, VISORNIC_INFINITE_RSP_WAIT);
        return 0;
}

/* visornic_close - disables the visornic device and stops the queues
 * @netdev: netdevice to stop.
 *
 * Disable the device and stop the transmit queue.
 *
 * Return 0 on success.
 */
static int visornic_close(struct net_device *netdev)
{
        visornic_disable_with_timeout(netdev, VISORNIC_INFINITE_RSP_WAIT);
        return 0;
}

/* devdata_xmits_outstanding - compute outstanding xmits
 * @devdata: visornic_devdata for device
 *
 * Return: Long integer representing the number of outstanding xmits.
 */
static unsigned long devdata_xmits_outstanding(struct visornic_devdata *devdata)
{
        if (devdata->chstat.sent_xmit >= devdata->chstat.got_xmit_done)
                return devdata->chstat.sent_xmit -
                        devdata->chstat.got_xmit_done;
        return (ULONG_MAX - devdata->chstat.got_xmit_done
                + devdata->chstat.sent_xmit + 1);
}

/* vnic_hit_high_watermark
 * @devdata:        Indicates visornic device we are checking.
 * @high_watermark: Max num of unacked xmits we will tolerate before we will
 *                  start throttling.
 *
 * Return: True iff the number of unacked xmits sent to the IO Partition is >=
 *         high_watermark. False otherwise.
 */
static bool vnic_hit_high_watermark(struct visornic_devdata *devdata,
                                    ulong high_watermark)
{
        return (devdata_xmits_outstanding(devdata) >= high_watermark);
}

/* vnic_hit_low_watermark
 * @devdata:       Indicates visornic device we are checking.
 * @low_watermark: We will wait until the num of unacked xmits drops to this
 *                 value or lower before we start transmitting again.
 *
 * Return: True iff the number of unacked xmits sent to the IO Partition is <=
 *         low_watermark.
 */
static bool vnic_hit_low_watermark(struct visornic_devdata *devdata,
                                   ulong low_watermark)
{
        return (devdata_xmits_outstanding(devdata) <= low_watermark);
}

/* visornic_xmit - send a packet to the IO Partition
 * @skb:    Packet to be sent.
 * @netdev: Net device the packet is being sent from.
 *
 * Convert the skb to a cmdrsp so the IO Partition can understand it, and send
 * the XMIT command to the IO Partition for processing. This function is
 * protected from concurrent calls by a spinlock xmit_lock in the net_device
 * struct. As soon as the function returns, it can be called again.
 *
 * Return: NETDEV_TX_OK.
 */
static int visornic_xmit(struct sk_buff *skb, struct net_device *netdev)
{
        struct visornic_devdata *devdata;
        int len, firstfraglen, padlen;
        struct uiscmdrsp *cmdrsp = NULL;
        unsigned long flags;
        int err;

        devdata = netdev_priv(netdev);
        spin_lock_irqsave(&devdata->priv_lock, flags);

        if (netif_queue_stopped(netdev) || devdata->server_down ||
            devdata->server_change_state) {
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                devdata->busy_cnt++;
                dev_dbg(&netdev->dev,
                        "%s busy - queue stopped\n", __func__);
                kfree_skb(skb);
                return NETDEV_TX_OK;
        }

        /* sk_buff struct is used to host network data throughout all the
         * linux network subsystems
         */
        len = skb->len;

        /* skb->len is the FULL length of data (including fragmentary portion)
         * skb->data_len is the length of the fragment portion in frags
         * skb->len - skb->data_len is size of the 1st fragment in skb->data
         * calculate the length of the first fragment that skb->data is
         * pointing to
         */
        firstfraglen = skb->len - skb->data_len;
        if (firstfraglen < ETH_HLEN) {
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                devdata->busy_cnt++;
                dev_err(&netdev->dev,
                        "%s busy - first frag too small (%d)\n",
                        __func__, firstfraglen);
                kfree_skb(skb);
                return NETDEV_TX_OK;
        }

        if (len < ETH_MIN_PACKET_SIZE &&
            ((skb_end_pointer(skb) - skb->data) >= ETH_MIN_PACKET_SIZE)) {
                /* pad the packet out to minimum size */
                padlen = ETH_MIN_PACKET_SIZE - len;
                memset(&skb->data[len], 0, padlen);
                skb->tail += padlen;
                skb->len += padlen;
                len += padlen;
                firstfraglen += padlen;
        }

        cmdrsp = devdata->xmit_cmdrsp;
        /* clear cmdrsp */
        memset(cmdrsp, 0, SIZEOF_CMDRSP);
        cmdrsp->net.type = NET_XMIT;
        cmdrsp->cmdtype = CMD_NET_TYPE;

        /* save the pointer to skb -- we'll need it for completion */
        cmdrsp->net.buf = skb;

        if (vnic_hit_high_watermark(devdata,
                                    devdata->max_outstanding_net_xmits)) {
                /* extra NET_XMITs queued over to IOVM - need to wait */
                devdata->chstat.reject_count++;
                if (!devdata->queuefullmsg_logged &&
                    ((devdata->chstat.reject_count & 0x3ff) == 1))
                        devdata->queuefullmsg_logged = 1;
                netif_stop_queue(netdev);
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                devdata->busy_cnt++;
                dev_dbg(&netdev->dev,
                        "%s busy - waiting for iovm to catch up\n",
                        __func__);
                kfree_skb(skb);
                return NETDEV_TX_OK;
        }
        if (devdata->queuefullmsg_logged)
                devdata->queuefullmsg_logged = 0;

        if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
                cmdrsp->net.xmt.lincsum.valid = 1;
                cmdrsp->net.xmt.lincsum.protocol = skb->protocol;
                if (skb_transport_header(skb) > skb->data) {
                        cmdrsp->net.xmt.lincsum.hrawoff =
                                skb_transport_header(skb) - skb->data;
                        cmdrsp->net.xmt.lincsum.hrawoff = 1;
                }
                if (skb_network_header(skb) > skb->data) {
                        cmdrsp->net.xmt.lincsum.nhrawoff =
                                skb_network_header(skb) - skb->data;
                        cmdrsp->net.xmt.lincsum.nhrawoffv = 1;
                }
                cmdrsp->net.xmt.lincsum.csum = skb->csum;
        } else {
                cmdrsp->net.xmt.lincsum.valid = 0;
        }

        /* save off the length of the entire data packet */
        cmdrsp->net.xmt.len = len;

        /* copy ethernet header from first frag into ocmdrsp
         * - everything else will be pass in frags & DMA'ed
         */
        memcpy(cmdrsp->net.xmt.ethhdr, skb->data, ETH_HLEN);

        /* copy frags info - from skb->data we need to only provide access
         * beyond eth header
         */
        cmdrsp->net.xmt.num_frags =
                visor_copy_fragsinfo_from_skb(skb, firstfraglen,
                                              MAX_PHYS_INFO,
                                              cmdrsp->net.xmt.frags);
        if (cmdrsp->net.xmt.num_frags < 0) {
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                devdata->busy_cnt++;
                dev_err(&netdev->dev,
                        "%s busy - copy frags failed\n", __func__);
                kfree_skb(skb);
                return NETDEV_TX_OK;
        }

        err = visorchannel_signalinsert(devdata->dev->visorchannel,
                                        IOCHAN_TO_IOPART, cmdrsp);
        if (err) {
                netif_stop_queue(netdev);
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                devdata->busy_cnt++;
                dev_dbg(&netdev->dev,
                        "%s busy - signalinsert failed\n", __func__);
                kfree_skb(skb);
                return NETDEV_TX_OK;
        }

        /* Track the skbs that have been sent to the IOVM for XMIT */
        skb_queue_head(&devdata->xmitbufhead, skb);

        /* update xmt stats */
        devdata->net_stats.tx_packets++;
        devdata->net_stats.tx_bytes += skb->len;
        devdata->chstat.sent_xmit++;

        /* check if we have hit the high watermark for netif_stop_queue() */
        if (vnic_hit_high_watermark(devdata,
                                    devdata->upper_threshold_net_xmits)) {
                /* extra NET_XMITs queued over to IOVM - need to wait */
                /* stop queue - call netif_wake_queue() after lower threshold */
                netif_stop_queue(netdev);
                dev_dbg(&netdev->dev,
                        "%s busy - invoking iovm flow control\n",
                        __func__);
                devdata->flow_control_upper_hits++;
        }
        spin_unlock_irqrestore(&devdata->priv_lock, flags);

        /* skb will be freed when we get back NET_XMIT_DONE */
        return NETDEV_TX_OK;
}

/* visornic_get_stats - returns net_stats of the visornic device
 * @netdev: netdevice.
 *
 * Return: Pointer to the net_device_stats struct for the device.
 */
static struct net_device_stats *visornic_get_stats(struct net_device *netdev)
{
        struct visornic_devdata *devdata = netdev_priv(netdev);

        return &devdata->net_stats;
}

/* visornic_change_mtu - changes mtu of device
 * @netdev: netdevice.
 * @new_mtu: Value of new mtu.
 *
 * The device's MTU cannot be changed by system; it must be changed via a
 * CONTROLVM message. All vnics and pnics in a switch have to have the same MTU
 * for everything to work. Currently not supported.
 *
 * Return: -EINVAL.
 */
static int visornic_change_mtu(struct net_device *netdev, int new_mtu)
{
        return -EINVAL;
}

/* visornic_set_multi - set visornic device flags
 * @netdev: netdevice.
 *
 * The only flag we currently support is IFF_PROMISC.
 */
static void visornic_set_multi(struct net_device *netdev)
{
        struct uiscmdrsp *cmdrsp;
        struct visornic_devdata *devdata = netdev_priv(netdev);
        int err = 0;

        if (devdata->old_flags == netdev->flags)
                return;

        if ((netdev->flags & IFF_PROMISC) ==
            (devdata->old_flags & IFF_PROMISC))
                goto out_save_flags;

        cmdrsp = kmalloc(SIZEOF_CMDRSP, GFP_ATOMIC);
        if (!cmdrsp)
                return;
        cmdrsp->cmdtype = CMD_NET_TYPE;
        cmdrsp->net.type = NET_RCV_PROMISC;
        cmdrsp->net.enbdis.context = netdev;
        cmdrsp->net.enbdis.enable =
                netdev->flags & IFF_PROMISC;
        err = visorchannel_signalinsert(devdata->dev->visorchannel,
                                        IOCHAN_TO_IOPART,
                                        cmdrsp);
        kfree(cmdrsp);
        if (err)
                return;

out_save_flags:
        devdata->old_flags = netdev->flags;
}

/* visornic_xmit_timeout - request to timeout the xmit
 * @netdev: netdevice.
 *
 * Queue the work and return. Make sure we have not already been informed that
 * the IO Partition is gone; if so, we will have already timed-out the xmits.
 */
static void visornic_xmit_timeout(struct net_device *netdev)
{
        struct visornic_devdata *devdata = netdev_priv(netdev);
        unsigned long flags;

        spin_lock_irqsave(&devdata->priv_lock, flags);
        if (devdata->going_away) {
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                dev_dbg(&devdata->dev->device,
                        "%s aborting because device removal pending\n",
                        __func__);
                return;
        }

        /* Ensure that a ServerDown message hasn't been received */
        if (!devdata->enabled ||
            (devdata->server_down && !devdata->server_change_state)) {
                dev_dbg(&netdev->dev, "%s no processing\n",
                        __func__);
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                return;
        }
        schedule_work(&devdata->timeout_reset);
        spin_unlock_irqrestore(&devdata->priv_lock, flags);
}

/* repost_return - repost rcv bufs that have come back
 * @cmdrsp: IO channel command struct to post.
 * @devdata: Visornic devdata for the device.
 * @skb: Socket buffer.
 * @netdev: netdevice.
 *
 * Repost rcv buffers that have been returned to us when we are finished
 * with them.
 *
 * Return: 0 for success, negative integer on error.
 */
static int repost_return(struct uiscmdrsp *cmdrsp,
                         struct visornic_devdata *devdata,
                         struct sk_buff *skb, struct net_device *netdev)
{
        struct net_pkt_rcv copy;
        int i = 0, cc, numreposted;
        int found_skb = 0;
        int status = 0;

        copy = cmdrsp->net.rcv;
        switch (copy.numrcvbufs) {
        case 0:
                devdata->n_rcv0++;
                break;
        case 1:
                devdata->n_rcv1++;
                break;
        case 2:
                devdata->n_rcv2++;
                break;
        default:
                devdata->n_rcvx++;
                break;
        }
        for (cc = 0, numreposted = 0; cc < copy.numrcvbufs; cc++) {
                for (i = 0; i < devdata->num_rcv_bufs; i++) {
                        if (devdata->rcvbuf[i] != copy.rcvbuf[cc])
                                continue;

                        if ((skb) && devdata->rcvbuf[i] == skb) {
                                devdata->found_repost_rcvbuf_cnt++;
                                found_skb = 1;
                                devdata->repost_found_skb_cnt++;
                        }
                        devdata->rcvbuf[i] = alloc_rcv_buf(netdev);
                        if (!devdata->rcvbuf[i]) {
                                devdata->num_rcv_bufs_could_not_alloc++;
                                devdata->alloc_failed_in_repost_rtn_cnt++;
                                status = -ENOMEM;
                                break;
                        }
                        status = post_skb(cmdrsp, devdata, devdata->rcvbuf[i]);
                        if (status) {
                                kfree_skb(devdata->rcvbuf[i]);
                                devdata->rcvbuf[i] = NULL;
                                break;
                        }
                        numreposted++;
                        break;
                }
        }
        if (numreposted != copy.numrcvbufs) {
                devdata->n_repost_deficit++;
                status = -EINVAL;
        }
        if (skb) {
                if (found_skb) {
                        kfree_skb(skb);
                } else {
                        status = -EINVAL;
                        devdata->bad_rcv_buf++;
                }
        }
        return status;
}

/* visornic_rx - handle receive packets coming back from IO Partition
 * @cmdrsp: Receive packet returned from IO Partition.
 *
 * Got a receive packet back from the IO Partition; handle it and send it up
 * the stack.

 * Return: 1 iff an skb was received, otherwise 0.
 */
static int visornic_rx(struct uiscmdrsp *cmdrsp)
{
        struct visornic_devdata *devdata;
        struct sk_buff *skb, *prev, *curr;
        struct net_device *netdev;
        int cc, currsize, off;
        struct ethhdr *eth;
        unsigned long flags;

        /* post new rcv buf to the other end using the cmdrsp we have at hand
         * post it without holding lock - but we'll use the signal lock to
         * synchronize the queue insert the cmdrsp that contains the net.rcv
         * is the one we are using to repost, so copy the info we need from it.
         */
        skb = cmdrsp->net.buf;
        netdev = skb->dev;

        devdata = netdev_priv(netdev);

        spin_lock_irqsave(&devdata->priv_lock, flags);
        atomic_dec(&devdata->num_rcvbuf_in_iovm);

        /* set length to how much was ACTUALLY received -
         * NOTE: rcv_done_len includes actual length of data rcvd
         * including ethhdr
         */
        skb->len = cmdrsp->net.rcv.rcv_done_len;

        /* update rcv stats - call it with priv_lock held */
        devdata->net_stats.rx_packets++;
        devdata->net_stats.rx_bytes += skb->len;

        /* test enabled while holding lock */
        if (!(devdata->enabled && devdata->enab_dis_acked)) {
                /* don't process it unless we're in enable mode and until
                 * we've gotten an ACK saying the other end got our RCV enable
                 */
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                repost_return(cmdrsp, devdata, skb, netdev);
                return 0;
        }

        spin_unlock_irqrestore(&devdata->priv_lock, flags);

        /* when skb was allocated, skb->dev, skb->data, skb->len and
         * skb->data_len were setup. AND, data has already put into the
         * skb (both first frag and in frags pages)
         * NOTE: firstfragslen is the amount of data in skb->data and that
         * which is not in nr_frags or frag_list. This is now simply
         * RCVPOST_BUF_SIZE. bump tail to show how much data is in
         * firstfrag & set data_len to show rest see if we have to chain
         * frag_list.
         */
        /* do PRECAUTIONARY check */
        if (skb->len > RCVPOST_BUF_SIZE) {
                if (cmdrsp->net.rcv.numrcvbufs < 2) {
                        if (repost_return(cmdrsp, devdata, skb, netdev) < 0)
                                dev_err(&devdata->netdev->dev,
                                        "repost_return failed");
                        return 0;
                }
                /* length rcvd is greater than firstfrag in this skb rcv buf  */
                /* amount in skb->data */
                skb->tail += RCVPOST_BUF_SIZE;
                /* amount that will be in frag_list */
                skb->data_len = skb->len - RCVPOST_BUF_SIZE;
        } else {
                /* data fits in this skb - no chaining - do
                 * PRECAUTIONARY check
                 */
                /* should be 1 */
                if (cmdrsp->net.rcv.numrcvbufs != 1) {
                        if (repost_return(cmdrsp, devdata, skb, netdev) < 0)
                                dev_err(&devdata->netdev->dev,
                                        "repost_return failed");
                        return 0;
                }
                skb->tail += skb->len;
                /* nothing rcvd in frag_list */
                skb->data_len = 0;
        }
        off = skb_tail_pointer(skb) - skb->data;

        /* amount we bumped tail by in the head skb
         * it is used to calculate the size of each chained skb below
         * it is also used to index into bufline to continue the copy
         * (for chansocktwopc)
         * if necessary chain the rcv skbs together.
         * NOTE: index 0 has the same as cmdrsp->net.rcv.skb; we need to
         * chain the rest to that one.
         * - do PRECAUTIONARY check
         */
        if (cmdrsp->net.rcv.rcvbuf[0] != skb) {
                if (repost_return(cmdrsp, devdata, skb, netdev) < 0)
                        dev_err(&devdata->netdev->dev, "repost_return failed");
                return 0;
        }

        if (cmdrsp->net.rcv.numrcvbufs > 1) {
                /* chain the various rcv buffers into the skb's frag_list. */
                /* Note: off was initialized above  */
                for (cc = 1, prev = NULL;
                     cc < cmdrsp->net.rcv.numrcvbufs; cc++) {
                        curr = (struct sk_buff *)cmdrsp->net.rcv.rcvbuf[cc];
                        curr->next = NULL;
                        /* start of list- set head */
                        if (!prev)
                                skb_shinfo(skb)->frag_list = curr;
                        else
                                prev->next = curr;
                        prev = curr;

                        /* should we set skb->len and skb->data_len for each
                         * buffer being chained??? can't hurt!
                         */
                        currsize = min(skb->len - off,
                                       (unsigned int)RCVPOST_BUF_SIZE);
                        curr->len = currsize;
                        curr->tail += currsize;
                        curr->data_len = 0;
                        off += currsize;
                }
                /* assert skb->len == off */
                if (skb->len != off) {
                        netdev_err(devdata->netdev,
                                   "something wrong; skb->len:%d != off:%d\n",
                                   skb->len, off);
                }
        }

        /* set up packet's protocol type using ethernet header - this
         * sets up skb->pkt_type & it also PULLS out the eth header
         */
        skb->protocol = eth_type_trans(skb, netdev);
        eth = eth_hdr(skb);
        skb->csum = 0;
        skb->ip_summed = CHECKSUM_NONE;

        do {
                /* accept all packets */
                if (netdev->flags & IFF_PROMISC)
                        break;
                if (skb->pkt_type == PACKET_BROADCAST) {
                        /* accept all broadcast packets */
                        if (netdev->flags & IFF_BROADCAST)
                                break;
                } else if (skb->pkt_type == PACKET_MULTICAST) {
                        if ((netdev->flags & IFF_MULTICAST) &&
                            (netdev_mc_count(netdev))) {
                                struct netdev_hw_addr *ha;
                                int found_mc = 0;

                                /* only accept multicast packets that we can
                                 * find in our multicast address list
                                 */
                                netdev_for_each_mc_addr(ha, netdev) {
                                        if (ether_addr_equal(eth->h_dest,
                                                             ha->addr)) {
                                                found_mc = 1;
                                                break;
                                        }
                                }
                                /* accept pkt, dest matches a multicast addr */
                                if (found_mc)
                                        break;
                        }
                /* accept packet, h_dest must match vnic  mac address */
                } else if (skb->pkt_type == PACKET_HOST) {
                        break;
                } else if (skb->pkt_type == PACKET_OTHERHOST) {
                        /* something is not right */
                        dev_err(&devdata->netdev->dev,
                                "**** FAILED to deliver rcv packet to OS; name:%s Dest:%pM VNIC:%pM\n",
                                netdev->name, eth->h_dest, netdev->dev_addr);
                }
                /* drop packet - don't forward it up to OS */
                devdata->n_rcv_packets_not_accepted++;
                repost_return(cmdrsp, devdata, skb, netdev);
                return 0;
        } while (0);

        netif_receive_skb(skb);
        /* netif_rx returns various values, but "in practice most drivers
         * ignore the return value
         */

        skb = NULL;
        /* whether the packet got dropped or handled, the skb is freed by
         * kernel code, so we shouldn't free it. but we should repost a
         * new rcv buffer.
         */
        repost_return(cmdrsp, devdata, skb, netdev);
        return 1;
}

/* devdata_initialize - initialize devdata structure
 * @devdata: visornic_devdata structure to initialize.
 * @dev:     visorbus_device it belongs to.
 *
 * Setup initial values for the visornic, based on channel and default values.
 *
 * Return: A pointer to the devdata structure.
 */
static struct visornic_devdata *devdata_initialize(
                                        struct visornic_devdata *devdata,
                                        struct visor_device *dev)
{
        devdata->dev = dev;
        devdata->incarnation_id = get_jiffies_64();
        return devdata;
}

/* devdata_release - free up references in devdata
 * @devdata: Struct to clean up.
 */
static void devdata_release(struct visornic_devdata *devdata)
{
        kfree(devdata->rcvbuf);
        kfree(devdata->cmdrsp_rcv);
        kfree(devdata->xmit_cmdrsp);
}

static const struct net_device_ops visornic_dev_ops = {
        .ndo_open = visornic_open,
        .ndo_stop = visornic_close,
        .ndo_start_xmit = visornic_xmit,
        .ndo_get_stats = visornic_get_stats,
        .ndo_change_mtu = visornic_change_mtu,
        .ndo_tx_timeout = visornic_xmit_timeout,
        .ndo_set_rx_mode = visornic_set_multi,
};

/* DebugFS code */
static ssize_t info_debugfs_read(struct file *file, char __user *buf,
                                 size_t len, loff_t *offset)
{
        ssize_t bytes_read = 0;
        int str_pos = 0;
        struct visornic_devdata *devdata;
        struct net_device *dev;
        char *vbuf;

        if (len > MAX_BUF)
                len = MAX_BUF;
        vbuf = kzalloc(len, GFP_KERNEL);
        if (!vbuf)
                return -ENOMEM;

        /* for each vnic channel dump out channel specific data */
        rcu_read_lock();
        for_each_netdev_rcu(current->nsproxy->net_ns, dev) {
                /* Only consider netdevs that are visornic, and are open */
                if (dev->netdev_ops != &visornic_dev_ops ||
                    (!netif_queue_stopped(dev)))
                        continue;

                devdata = netdev_priv(dev);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     "netdev = %s (0x%p), MAC Addr %pM\n",
                                     dev->name,
                                     dev,
                                     dev->dev_addr);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     "VisorNic Dev Info = 0x%p\n", devdata);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " num_rcv_bufs = %d\n",
                                     devdata->num_rcv_bufs);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " max_outstanding_next_xmits = %lu\n",
                                    devdata->max_outstanding_net_xmits);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " upper_threshold_net_xmits = %lu\n",
                                     devdata->upper_threshold_net_xmits);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " lower_threshold_net_xmits = %lu\n",
                                     devdata->lower_threshold_net_xmits);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " queuefullmsg_logged = %d\n",
                                     devdata->queuefullmsg_logged);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " chstat.got_rcv = %lu\n",
                                     devdata->chstat.got_rcv);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " chstat.got_enbdisack = %lu\n",
                                     devdata->chstat.got_enbdisack);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " chstat.got_xmit_done = %lu\n",
                                     devdata->chstat.got_xmit_done);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " chstat.xmit_fail = %lu\n",
                                     devdata->chstat.xmit_fail);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " chstat.sent_enbdis = %lu\n",
                                     devdata->chstat.sent_enbdis);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " chstat.sent_promisc = %lu\n",
                                     devdata->chstat.sent_promisc);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " chstat.sent_post = %lu\n",
                                     devdata->chstat.sent_post);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " chstat.sent_post_failed = %lu\n",
                                     devdata->chstat.sent_post_failed);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " chstat.sent_xmit = %lu\n",
                                     devdata->chstat.sent_xmit);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " chstat.reject_count = %lu\n",
                                     devdata->chstat.reject_count);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " chstat.extra_rcvbufs_sent = %lu\n",
                                     devdata->chstat.extra_rcvbufs_sent);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " n_rcv0 = %lu\n", devdata->n_rcv0);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " n_rcv1 = %lu\n", devdata->n_rcv1);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " n_rcv2 = %lu\n", devdata->n_rcv2);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " n_rcvx = %lu\n", devdata->n_rcvx);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " num_rcvbuf_in_iovm = %d\n",
                                     atomic_read(&devdata->num_rcvbuf_in_iovm));
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " alloc_failed_in_if_needed_cnt = %lu\n",
                                     devdata->alloc_failed_in_if_needed_cnt);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " alloc_failed_in_repost_rtn_cnt = %lu\n",
                                     devdata->alloc_failed_in_repost_rtn_cnt);
                /* str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                 *                   " inner_loop_limit_reached_cnt = %lu\n",
                 *                   devdata->inner_loop_limit_reached_cnt);
                 */
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " found_repost_rcvbuf_cnt = %lu\n",
                                     devdata->found_repost_rcvbuf_cnt);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " repost_found_skb_cnt = %lu\n",
                                     devdata->repost_found_skb_cnt);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " n_repost_deficit = %lu\n",
                                     devdata->n_repost_deficit);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " bad_rcv_buf = %lu\n",
                                     devdata->bad_rcv_buf);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " n_rcv_packets_not_accepted = %lu\n",
                                     devdata->n_rcv_packets_not_accepted);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " interrupts_rcvd = %llu\n",
                                     devdata->interrupts_rcvd);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " interrupts_notme = %llu\n",
                                     devdata->interrupts_notme);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " interrupts_disabled = %llu\n",
                                     devdata->interrupts_disabled);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " busy_cnt = %llu\n",
                                     devdata->busy_cnt);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " flow_control_upper_hits = %llu\n",
                                     devdata->flow_control_upper_hits);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " flow_control_lower_hits = %llu\n",
                                     devdata->flow_control_lower_hits);
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " netif_queue = %s\n",
                                     netif_queue_stopped(devdata->netdev) ?
                                     "stopped" : "running");
                str_pos += scnprintf(vbuf + str_pos, len - str_pos,
                                     " xmits_outstanding = %lu\n",
                                     devdata_xmits_outstanding(devdata));
        }
        rcu_read_unlock();
        bytes_read = simple_read_from_buffer(buf, len, offset, vbuf, str_pos);
        kfree(vbuf);
        return bytes_read;
}

static struct dentry *visornic_debugfs_dir;
static const struct file_operations debugfs_info_fops = {
        .read = info_debugfs_read,
};

/* send_rcv_posts_if_needed - send receive buffers to the IO Partition.
 * @devdata: Visornic device.
 */
static void send_rcv_posts_if_needed(struct visornic_devdata *devdata)
{
        int i;
        struct net_device *netdev;
        struct uiscmdrsp *cmdrsp = devdata->cmdrsp_rcv;
        int cur_num_rcv_bufs_to_alloc, rcv_bufs_allocated;
        int err;

        /* don't do this until vnic is marked ready */
        if (!(devdata->enabled && devdata->enab_dis_acked))
                return;

        netdev = devdata->netdev;
        rcv_bufs_allocated = 0;
        /* this code is trying to prevent getting stuck here forever,
         * but still retry it if you cant allocate them all this time.
         */
        cur_num_rcv_bufs_to_alloc = devdata->num_rcv_bufs_could_not_alloc;
        while (cur_num_rcv_bufs_to_alloc > 0) {
                cur_num_rcv_bufs_to_alloc--;
                for (i = 0; i < devdata->num_rcv_bufs; i++) {
                        if (devdata->rcvbuf[i])
                                continue;
                        devdata->rcvbuf[i] = alloc_rcv_buf(netdev);
                        if (!devdata->rcvbuf[i]) {
                                devdata->alloc_failed_in_if_needed_cnt++;
                                break;
                        }
                        rcv_bufs_allocated++;
                        err = post_skb(cmdrsp, devdata, devdata->rcvbuf[i]);
                        if (err) {
                                kfree_skb(devdata->rcvbuf[i]);
                                devdata->rcvbuf[i] = NULL;
                                break;
                        }
                        devdata->chstat.extra_rcvbufs_sent++;
                }
        }
        devdata->num_rcv_bufs_could_not_alloc -= rcv_bufs_allocated;
}

/* drain_resp_queue - drains and ignores all messages from the resp queue
 * @cmdrsp:  IO channel command response message.
 * @devdata: Visornic device to drain.
 */
static void drain_resp_queue(struct uiscmdrsp *cmdrsp,
                             struct visornic_devdata *devdata)
{
        while (!visorchannel_signalremove(devdata->dev->visorchannel,
                                          IOCHAN_FROM_IOPART,
                                          cmdrsp))
                ;
}

/* service_resp_queue - drain the response queue
 * @cmdrsp:  IO channel command response message.
 * @devdata: Visornic device to drain.
 * @rx_work_done:
 * @budget:
 *
 * Drain the response queue of any responses from the IO Partition. Process the
 * responses as we get them.
 */
static void service_resp_queue(struct uiscmdrsp *cmdrsp,
                               struct visornic_devdata *devdata,
                               int *rx_work_done, int budget)
{
        unsigned long flags;
        struct net_device *netdev;

        while (*rx_work_done < budget) {
                /* TODO: CLIENT ACQUIRE -- Don't really need this at the
                 * moment
                 */
                /* queue empty */
                if (visorchannel_signalremove(devdata->dev->visorchannel,
                                              IOCHAN_FROM_IOPART,
                                              cmdrsp))
                        break;

                switch (cmdrsp->net.type) {
                case NET_RCV:
                        devdata->chstat.got_rcv++;
                        /* process incoming packet */
                        *rx_work_done += visornic_rx(cmdrsp);
                        break;
                case NET_XMIT_DONE:
                        spin_lock_irqsave(&devdata->priv_lock, flags);
                        devdata->chstat.got_xmit_done++;
                        if (cmdrsp->net.xmtdone.xmt_done_result)
                                devdata->chstat.xmit_fail++;
                        /* only call queue wake if we stopped it */
                        netdev = ((struct sk_buff *)cmdrsp->net.buf)->dev;
                        /* ASSERT netdev == vnicinfo->netdev; */
                        if (netdev == devdata->netdev &&
                            netif_queue_stopped(netdev)) {
                                /* check if we have crossed the lower watermark
                                 * for netif_wake_queue()
                                 */
                                if (vnic_hit_low_watermark
                                    (devdata,
                                     devdata->lower_threshold_net_xmits)) {
                                        /* enough NET_XMITs completed
                                         * so can restart netif queue
                                         */
                                        netif_wake_queue(netdev);
                                        devdata->flow_control_lower_hits++;
                                }
                        }
                        skb_unlink(cmdrsp->net.buf, &devdata->xmitbufhead);
                        spin_unlock_irqrestore(&devdata->priv_lock, flags);
                        kfree_skb(cmdrsp->net.buf);
                        break;
                case NET_RCV_ENBDIS_ACK:
                        devdata->chstat.got_enbdisack++;
                        netdev = (struct net_device *)
                        cmdrsp->net.enbdis.context;
                        spin_lock_irqsave(&devdata->priv_lock, flags);
                        devdata->enab_dis_acked = 1;
                        spin_unlock_irqrestore(&devdata->priv_lock, flags);

                        if (devdata->server_down &&
                            devdata->server_change_state) {
                                /* Inform Linux that the link is up */
                                devdata->server_down = false;
                                devdata->server_change_state = false;
                                netif_wake_queue(netdev);
                                netif_carrier_on(netdev);
                        }
                        break;
                case NET_CONNECT_STATUS:
                        netdev = devdata->netdev;
                        if (cmdrsp->net.enbdis.enable == 1) {
                                spin_lock_irqsave(&devdata->priv_lock, flags);
                                devdata->enabled = cmdrsp->net.enbdis.enable;
                                spin_unlock_irqrestore(&devdata->priv_lock,
                                                       flags);
                                netif_wake_queue(netdev);
                                netif_carrier_on(netdev);
                        } else {
                                netif_stop_queue(netdev);
                                netif_carrier_off(netdev);
                                spin_lock_irqsave(&devdata->priv_lock, flags);
                                devdata->enabled = cmdrsp->net.enbdis.enable;
                                spin_unlock_irqrestore(&devdata->priv_lock,
                                                       flags);
                        }
                        break;
                default:
                        break;
                }
                /* cmdrsp is now available for reuse  */
        }
}

static int visornic_poll(struct napi_struct *napi, int budget)
{
        struct visornic_devdata *devdata = container_of(napi,
                                                        struct visornic_devdata,
                                                        napi);
        int rx_count = 0;

        send_rcv_posts_if_needed(devdata);
        service_resp_queue(devdata->cmdrsp, devdata, &rx_count, budget);

        /* If there aren't any more packets to receive stop the poll */
        if (rx_count < budget)
                napi_complete_done(napi, rx_count);

        return rx_count;
}

/* poll_for_irq - checks the status of the response queue
 * @v: Void pointer to the visronic devdata struct.
 *
 * Main function of the vnic_incoming thread. Periodically check the response
 * queue and drain it if needed.
 */
static void poll_for_irq(unsigned long v)
{
        struct visornic_devdata *devdata = (struct visornic_devdata *)v;

        if (!visorchannel_signalempty(
                                   devdata->dev->visorchannel,
                                   IOCHAN_FROM_IOPART))
                napi_schedule(&devdata->napi);

        atomic_set(&devdata->interrupt_rcvd, 0);

        mod_timer(&devdata->irq_poll_timer, msecs_to_jiffies(2));
}

/* visornic_probe - probe function for visornic devices
 * @dev: The visor device discovered.
 *
 * Called when visorbus discovers a visornic device on its bus. It creates a new
 * visornic ethernet adapter.
 *
 * Return: 0 on success, or negative integer on error.
 */
static int visornic_probe(struct visor_device *dev)
{
        struct visornic_devdata *devdata = NULL;
        struct net_device *netdev = NULL;
        int err;
        int channel_offset = 0;
        u64 features;

        netdev = alloc_etherdev(sizeof(struct visornic_devdata));
        if (!netdev) {
                dev_err(&dev->device,
                        "%s alloc_etherdev failed\n", __func__);
                return -ENOMEM;
        }

        netdev->netdev_ops = &visornic_dev_ops;
        netdev->watchdog_timeo = 5 * HZ;
        SET_NETDEV_DEV(netdev, &dev->device);

        /* Get MAC address from channel and read it into the device. */
        netdev->addr_len = ETH_ALEN;
        channel_offset = offsetof(struct visor_io_channel, vnic.macaddr);
        err = visorbus_read_channel(dev, channel_offset, netdev->dev_addr,
                                    ETH_ALEN);
        if (err < 0) {
                dev_err(&dev->device,
                        "%s failed to get mac addr from chan (%d)\n",
                        __func__, err);
                goto cleanup_netdev;
        }

        devdata = devdata_initialize(netdev_priv(netdev), dev);
        if (!devdata) {
                dev_err(&dev->device,
                        "%s devdata_initialize failed\n", __func__);
                err = -ENOMEM;
                goto cleanup_netdev;
        }
        /* don't trust messages laying around in the channel */
        drain_resp_queue(devdata->cmdrsp, devdata);

        devdata->netdev = netdev;
        dev_set_drvdata(&dev->device, devdata);
        init_waitqueue_head(&devdata->rsp_queue);
        spin_lock_init(&devdata->priv_lock);
        /* not yet */
        devdata->enabled = 0;
        atomic_set(&devdata->usage, 1);

        /* Setup rcv bufs */
        channel_offset = offsetof(struct visor_io_channel, vnic.num_rcv_bufs);
        err = visorbus_read_channel(dev, channel_offset,
                                    &devdata->num_rcv_bufs, 4);
        if (err) {
                dev_err(&dev->device,
                        "%s failed to get #rcv bufs from chan (%d)\n",
                        __func__, err);
                goto cleanup_netdev;
        }

        devdata->rcvbuf = kcalloc(devdata->num_rcv_bufs,
                                  sizeof(struct sk_buff *), GFP_KERNEL);
        if (!devdata->rcvbuf) {
                err = -ENOMEM;
                goto cleanup_netdev;
        }

        /* set the net_xmit outstanding threshold
         * always leave two slots open but you should have 3 at a minimum
         * note that max_outstanding_net_xmits must be > 0
         */
        devdata->max_outstanding_net_xmits =
                max_t(unsigned long, 3, ((devdata->num_rcv_bufs / 3) - 2));
        devdata->upper_threshold_net_xmits =
                max_t(unsigned long,
                      2, (devdata->max_outstanding_net_xmits - 1));
        devdata->lower_threshold_net_xmits =
                max_t(unsigned long,
                      1, (devdata->max_outstanding_net_xmits / 2));

        skb_queue_head_init(&devdata->xmitbufhead);

        /* create a cmdrsp we can use to post and unpost rcv buffers */
        devdata->cmdrsp_rcv = kmalloc(SIZEOF_CMDRSP, GFP_ATOMIC);
        if (!devdata->cmdrsp_rcv) {
                err = -ENOMEM;
                goto cleanup_rcvbuf;
        }
        devdata->xmit_cmdrsp = kmalloc(SIZEOF_CMDRSP, GFP_ATOMIC);
        if (!devdata->xmit_cmdrsp) {
                err = -ENOMEM;
                goto cleanup_cmdrsp_rcv;
        }
        INIT_WORK(&devdata->timeout_reset, visornic_timeout_reset);
        devdata->server_down = false;
        devdata->server_change_state = false;

        /*set the default mtu */
        channel_offset = offsetof(struct visor_io_channel, vnic.mtu);
        err = visorbus_read_channel(dev, channel_offset, &netdev->mtu, 4);
        if (err) {
                dev_err(&dev->device,
                        "%s failed to get mtu from chan (%d)\n",
                        __func__, err);
                goto cleanup_xmit_cmdrsp;
        }

        /* TODO: Setup Interrupt information */
        /* Let's start our threads to get responses */
        netif_napi_add(netdev, &devdata->napi, visornic_poll, NAPI_WEIGHT);

        setup_timer(&devdata->irq_poll_timer, poll_for_irq,
                    (unsigned long)devdata);
        /* Note: This time has to start running before the while
         * loop below because the napi routine is responsible for
         * setting enab_dis_acked
         */
        mod_timer(&devdata->irq_poll_timer, msecs_to_jiffies(2));

        channel_offset = offsetof(struct visor_io_channel,
                                  channel_header.features);
        err = visorbus_read_channel(dev, channel_offset, &features, 8);
        if (err) {
                dev_err(&dev->device,
                        "%s failed to get features from chan (%d)\n",
                        __func__, err);
                goto cleanup_napi_add;
        }

        features |= VISOR_CHANNEL_IS_POLLING;
        features |= VISOR_DRIVER_ENHANCED_RCVBUF_CHECKING;
        err = visorbus_write_channel(dev, channel_offset, &features, 8);
        if (err) {
                dev_err(&dev->device,
                        "%s failed to set features in chan (%d)\n",
                        __func__, err);
                goto cleanup_napi_add;
        }

        /* Note: Interrupts have to be enable before the while
         * loop below because the napi routine is responsible for
         * setting enab_dis_acked
         */
        visorbus_enable_channel_interrupts(dev);

        err = register_netdev(netdev);
        if (err) {
                dev_err(&dev->device,
                        "%s register_netdev failed (%d)\n", __func__, err);
                goto cleanup_napi_add;
        }

        /* create debug/sysfs directories */
        devdata->eth_debugfs_dir = debugfs_create_dir(netdev->name,
                                                      visornic_debugfs_dir);
        if (!devdata->eth_debugfs_dir) {
                dev_err(&dev->device,
                        "%s debugfs_create_dir %s failed\n",
                        __func__, netdev->name);
                err = -ENOMEM;
                goto cleanup_register_netdev;
        }

        dev_info(&dev->device, "%s success netdev=%s\n",
                 __func__, netdev->name);
        return 0;

cleanup_register_netdev:
        unregister_netdev(netdev);

cleanup_napi_add:
        del_timer_sync(&devdata->irq_poll_timer);
        netif_napi_del(&devdata->napi);

cleanup_xmit_cmdrsp:
        kfree(devdata->xmit_cmdrsp);

cleanup_cmdrsp_rcv:
        kfree(devdata->cmdrsp_rcv);

cleanup_rcvbuf:
        kfree(devdata->rcvbuf);

cleanup_netdev:
        free_netdev(netdev);
        return err;
}

/* host_side_disappeared - IO Partition is gone
 * @devdata: Device object.
 *
 * IO partition servicing this device is gone; do cleanup.
 */
static void host_side_disappeared(struct visornic_devdata *devdata)
{
        unsigned long flags;

        spin_lock_irqsave(&devdata->priv_lock, flags);
        /* indicate device destroyed */
        devdata->dev = NULL;
        spin_unlock_irqrestore(&devdata->priv_lock, flags);
}

/* visornic_remove - called when visornic dev goes away
 * @dev: Visornic device that is being removed.
 *
 * Called when DEVICE_DESTROY gets called to remove device.
 */
static void visornic_remove(struct visor_device *dev)
{
        struct visornic_devdata *devdata = dev_get_drvdata(&dev->device);
        struct net_device *netdev;
        unsigned long flags;

        if (!devdata) {
                dev_err(&dev->device, "%s no devdata\n", __func__);
                return;
        }
        spin_lock_irqsave(&devdata->priv_lock, flags);
        if (devdata->going_away) {
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                dev_err(&dev->device, "%s already being removed\n", __func__);
                return;
        }
        devdata->going_away = true;
        spin_unlock_irqrestore(&devdata->priv_lock, flags);
        netdev = devdata->netdev;
        if (!netdev) {
                dev_err(&dev->device, "%s not net device\n", __func__);
                return;
        }

        /* going_away prevents new items being added to the workqueues */
        cancel_work_sync(&devdata->timeout_reset);

        debugfs_remove_recursive(devdata->eth_debugfs_dir);
        /* this will call visornic_close() */
        unregister_netdev(netdev);

        del_timer_sync(&devdata->irq_poll_timer);
        netif_napi_del(&devdata->napi);

        dev_set_drvdata(&dev->device, NULL);
        host_side_disappeared(devdata);
        devdata_release(devdata);
        free_netdev(netdev);
}

/* visornic_pause - called when IO Part disappears
 * @dev:           Visornic device that is being serviced.
 * @complete_func: Call when finished.
 *
 * Called when the IO Partition has gone down. Need to free up resources and
 * wait for IO partition to come back. Mark link as down and don't attempt any
 * DMA. When we have freed memory, call the complete_func so that Command knows
 * we are done. If we don't call complete_func, the IO Partition will never
 * come back.
 *
 * Return: 0 on success.
 */
static int visornic_pause(struct visor_device *dev,
                          visorbus_state_complete_func complete_func)
{
        struct visornic_devdata *devdata = dev_get_drvdata(&dev->device);

        visornic_serverdown(devdata, complete_func);
        return 0;
}

/* visornic_resume - called when IO Partition has recovered
 * @dev:           Visornic device that is being serviced.
 * @compelte_func: Call when finished.
 *
 * Called when the IO partition has recovered. Re-establish connection to the IO
 * Partition and set the link up. Okay to do DMA again.
 *
 * Returns 0 for success, negative integer on error.
 */
static int visornic_resume(struct visor_device *dev,
                           visorbus_state_complete_func complete_func)
{
        struct visornic_devdata *devdata;
        struct net_device *netdev;
        unsigned long flags;

        devdata = dev_get_drvdata(&dev->device);
        if (!devdata) {
                dev_err(&dev->device, "%s no devdata\n", __func__);
                return -EINVAL;
        }

        netdev = devdata->netdev;

        spin_lock_irqsave(&devdata->priv_lock, flags);
        if (devdata->server_change_state) {
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                dev_err(&dev->device, "%s server already changing state\n",
                        __func__);
                return -EINVAL;
        }
        if (!devdata->server_down) {
                spin_unlock_irqrestore(&devdata->priv_lock, flags);
                dev_err(&dev->device, "%s server not down\n", __func__);
                complete_func(dev, 0);
                return 0;
        }
        devdata->server_change_state = true;
        spin_unlock_irqrestore(&devdata->priv_lock, flags);

        /* Must transition channel to ATTACHED state BEFORE
         * we can start using the device again.
         * TODO: State transitions
         */
        mod_timer(&devdata->irq_poll_timer, msecs_to_jiffies(2));

        rtnl_lock();
        dev_open(netdev);
        rtnl_unlock();

        complete_func(dev, 0);
        return 0;
}

/* This is used to tell the visorbus driver which types of visor devices
 * we support, and what functions to call when a visor device that we support
 * is attached or removed.
 */
static struct visor_driver visornic_driver = {
        .name = "visornic",
        .owner = THIS_MODULE,
        .channel_types = visornic_channel_types,
        .probe = visornic_probe,
        .remove = visornic_remove,
        .pause = visornic_pause,
        .resume = visornic_resume,
        .channel_interrupt = NULL,
};

/* visornic_init - init function
 *
 * Init function for the visornic driver. Do initial driver setup and wait
 * for devices.
 *
 * Return: 0 on success, negative integer on error.
 */
static int visornic_init(void)
{
        struct dentry *ret;
        int err = -ENOMEM;

        visornic_debugfs_dir = debugfs_create_dir("visornic", NULL);
        if (!visornic_debugfs_dir)
                return err;

        ret = debugfs_create_file("info", 0400, visornic_debugfs_dir, NULL,
                                  &debugfs_info_fops);
        if (!ret)
                goto cleanup_debugfs;
        ret = debugfs_create_file("enable_ints", 0200, visornic_debugfs_dir,
                                  NULL, &debugfs_enable_ints_fops);
        if (!ret)
                goto cleanup_debugfs;

        err = visorbus_register_visor_driver(&visornic_driver);
        if (err)
                goto cleanup_debugfs;

        return 0;

cleanup_debugfs:
        debugfs_remove_recursive(visornic_debugfs_dir);
        return err;
}

/* visornic_cleanup - driver exit routine
 *
 * Unregister driver from the bus and free up memory.
 */
static void visornic_cleanup(void)
{
        visorbus_unregister_visor_driver(&visornic_driver);
        debugfs_remove_recursive(visornic_debugfs_dir);
}

module_init(visornic_init);
module_exit(visornic_cleanup);

MODULE_AUTHOR("Unisys");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("s-Par NIC driver for virtual network devices");