/*
 * Copyright 2014 Cisco Systems, Inc.  All rights reserved.
 *
 * This program is free software; you may redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/module.h>
#include <linux/mempool.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/skbuff.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_tcq.h>

#include "snic.h"
#include "snic_fwint.h"

#define PCI_DEVICE_ID_CISCO_SNIC        0x0046

/* Supported devices by snic module */
static struct pci_device_id snic_id_table[] = {
        {PCI_DEVICE(0x1137, PCI_DEVICE_ID_CISCO_SNIC) },
        { 0, }  /* end of table */
};

unsigned int snic_log_level = 0x0;
module_param(snic_log_level, int, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(snic_log_level, "bitmask for snic logging levels");

#ifdef CONFIG_SCSI_SNIC_DEBUG_FS
unsigned int snic_trace_max_pages = 16;
module_param(snic_trace_max_pages, uint, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(snic_trace_max_pages,
                "Total allocated memory pages for snic trace buffer");

#endif
unsigned int snic_max_qdepth = SNIC_DFLT_QUEUE_DEPTH;
module_param(snic_max_qdepth, uint, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(snic_max_qdepth, "Queue depth to report for each LUN");

/*
 * snic_slave_alloc : callback function to SCSI Mid Layer, called on
 * scsi device initialization.
 */
static int
snic_slave_alloc(struct scsi_device *sdev)
{
        struct snic_tgt *tgt = starget_to_tgt(scsi_target(sdev));

        if (!tgt || snic_tgt_chkready(tgt))
                return -ENXIO;

        return 0;
}

/*
 * snic_slave_configure : callback function to SCSI Mid Layer, called on
 * scsi device initialization.
 */
static int
snic_slave_configure(struct scsi_device *sdev)
{
        struct snic *snic = shost_priv(sdev->host);
        u32 qdepth = 0, max_ios = 0;
        int tmo = SNIC_DFLT_CMD_TIMEOUT * HZ;

        /* Set Queue Depth */
        max_ios = snic_max_qdepth;
        qdepth = min_t(u32, max_ios, SNIC_MAX_QUEUE_DEPTH);
        scsi_change_queue_depth(sdev, qdepth);

        if (snic->fwinfo.io_tmo > 1)
                tmo = snic->fwinfo.io_tmo * HZ;

        /* FW requires extended timeouts */
        blk_queue_rq_timeout(sdev->request_queue, tmo);

        return 0;
}

static int
snic_change_queue_depth(struct scsi_device *sdev, int qdepth)
{
        struct snic *snic = shost_priv(sdev->host);
        int qsz = 0;

        qsz = min_t(u32, qdepth, SNIC_MAX_QUEUE_DEPTH);
        if (qsz < sdev->queue_depth)
                atomic64_inc(&snic->s_stats.misc.qsz_rampdown);
        else if (qsz > sdev->queue_depth)
                atomic64_inc(&snic->s_stats.misc.qsz_rampup);

        atomic64_set(&snic->s_stats.misc.last_qsz, sdev->queue_depth);

        scsi_change_queue_depth(sdev, qsz);

        return sdev->queue_depth;
}

static struct scsi_host_template snic_host_template = {
        .module = THIS_MODULE,
        .name = SNIC_DRV_NAME,
        .queuecommand = snic_queuecommand,
        .eh_abort_handler = snic_abort_cmd,
        .eh_device_reset_handler = snic_device_reset,
        .eh_host_reset_handler = snic_host_reset,
        .slave_alloc = snic_slave_alloc,
        .slave_configure = snic_slave_configure,
        .change_queue_depth = snic_change_queue_depth,
        .this_id = -1,
        .cmd_per_lun = SNIC_DFLT_QUEUE_DEPTH,
        .can_queue = SNIC_MAX_IO_REQ,
        .use_clustering = ENABLE_CLUSTERING,
        .sg_tablesize = SNIC_MAX_SG_DESC_CNT,
        .max_sectors = 0x800,
        .shost_attrs = snic_attrs,
        .track_queue_depth = 1,
        .cmd_size = sizeof(struct snic_internal_io_state),
        .proc_name = "snic_scsi",
};

/*
 * snic_handle_link_event : Handles link events such as link up/down/error
 */
void
snic_handle_link_event(struct snic *snic)
{
        unsigned long flags;

        spin_lock_irqsave(&snic->snic_lock, flags);
        if (snic->stop_link_events) {
                spin_unlock_irqrestore(&snic->snic_lock, flags);

                return;
        }
        spin_unlock_irqrestore(&snic->snic_lock, flags);

        queue_work(snic_glob->event_q, &snic->link_work);
} /* end of snic_handle_link_event */

/*
 * snic_notify_set : sets notification area
 * This notification area is to receive events from fw
 * Note: snic supports only MSIX interrupts, in which we can just call
 *  svnic_dev_notify_set directly
 */
static int
snic_notify_set(struct snic *snic)
{
        int ret = 0;
        enum vnic_dev_intr_mode intr_mode;

        intr_mode = svnic_dev_get_intr_mode(snic->vdev);

        if (intr_mode == VNIC_DEV_INTR_MODE_MSIX) {
                ret = svnic_dev_notify_set(snic->vdev, SNIC_MSIX_ERR_NOTIFY);
        } else {
                SNIC_HOST_ERR(snic->shost,
                              "Interrupt mode should be setup before devcmd notify set %d\n",
                              intr_mode);
                ret = -1;
        }

        return ret;
} /* end of snic_notify_set */

/*
 * snic_dev_wait : polls vnic open status.
 */
static int
snic_dev_wait(struct vnic_dev *vdev,
                int (*start)(struct vnic_dev *, int),
                int (*finished)(struct vnic_dev *, int *),
                int arg)
{
        unsigned long time;
        int ret, done;
        int retry_cnt = 0;

        ret = start(vdev, arg);
        if (ret)
                return ret;

        /*
         * Wait for func to complete...2 seconds max.
         *
         * Sometimes schedule_timeout_uninterruptible take long time
         * to wakeup, which results skipping retry. The retry counter
         * ensures to retry at least two times.
         */
        time = jiffies + (HZ * 2);
        do {
                ret = finished(vdev, &done);
                if (ret)
                        return ret;

                if (done)
                        return 0;
                schedule_timeout_uninterruptible(HZ/10);
                ++retry_cnt;
        } while (time_after(time, jiffies) || (retry_cnt < 3));

        return -ETIMEDOUT;
} /* end of snic_dev_wait */

/*
 * snic_cleanup: called by snic_remove
 * Stops the snic device, masks all interrupts, Completed CQ entries are
 * drained. Posted WQ/RQ/Copy-WQ entries are cleanup
 */
static int
snic_cleanup(struct snic *snic)
{
        unsigned int i;
        int ret;

        svnic_dev_disable(snic->vdev);
        for (i = 0; i < snic->intr_count; i++)
                svnic_intr_mask(&snic->intr[i]);

        for (i = 0; i < snic->wq_count; i++) {
                ret = svnic_wq_disable(&snic->wq[i]);
                if (ret)
                        return ret;
        }

        /* Clean up completed IOs */
        snic_fwcq_cmpl_handler(snic, -1);

        snic_wq_cmpl_handler(snic, -1);

        /* Clean up the IOs that have not completed */
        for (i = 0; i < snic->wq_count; i++)
                svnic_wq_clean(&snic->wq[i], snic_free_wq_buf);

        for (i = 0; i < snic->cq_count; i++)
                svnic_cq_clean(&snic->cq[i]);

        for (i = 0; i < snic->intr_count; i++)
                svnic_intr_clean(&snic->intr[i]);

        /* Cleanup snic specific requests */
        snic_free_all_untagged_reqs(snic);

        /* Cleanup Pending SCSI commands */
        snic_shutdown_scsi_cleanup(snic);

        for (i = 0; i < SNIC_REQ_MAX_CACHES; i++)
                mempool_destroy(snic->req_pool[i]);

        return 0;
} /* end of snic_cleanup */


static void
snic_iounmap(struct snic *snic)
{
        if (snic->bar0.vaddr)
                iounmap(snic->bar0.vaddr);
}

/*
 * snic_vdev_open_done : polls for svnic_dev_open cmd completion.
 */
static int
snic_vdev_open_done(struct vnic_dev *vdev, int *done)
{
        struct snic *snic = svnic_dev_priv(vdev);
        int ret;
        int nretries = 5;

        do {
                ret = svnic_dev_open_done(vdev, done);
                if (ret == 0)
                        break;

                SNIC_HOST_INFO(snic->shost, "VNIC_DEV_OPEN Timedout.\n");
        } while (nretries--);

        return ret;
} /* end of snic_vdev_open_done */

/*
 * snic_add_host : registers scsi host with ML
 */
static int
snic_add_host(struct Scsi_Host *shost, struct pci_dev *pdev)
{
        int ret = 0;

        ret = scsi_add_host(shost, &pdev->dev);
        if (ret) {
                SNIC_HOST_ERR(shost,
                              "snic: scsi_add_host failed. %d\n",
                              ret);

                return ret;
        }

        SNIC_BUG_ON(shost->work_q != NULL);
        snprintf(shost->work_q_name, sizeof(shost->work_q_name), "scsi_wq_%d",
                 shost->host_no);
        shost->work_q = create_singlethread_workqueue(shost->work_q_name);
        if (!shost->work_q) {
                SNIC_HOST_ERR(shost, "Failed to Create ScsiHost wq.\n");

                ret = -ENOMEM;
        }

        return ret;
} /* end of snic_add_host */

static void
snic_del_host(struct Scsi_Host *shost)
{
        if (!shost->work_q)
                return;

        destroy_workqueue(shost->work_q);
        shost->work_q = NULL;
        scsi_remove_host(shost);
}

int
snic_get_state(struct snic *snic)
{
        return atomic_read(&snic->state);
}

void
snic_set_state(struct snic *snic, enum snic_state state)
{
        SNIC_HOST_INFO(snic->shost, "snic state change from %s to %s\n",
                       snic_state_to_str(snic_get_state(snic)),
                       snic_state_to_str(state));

        atomic_set(&snic->state, state);
}

/*
 * snic_probe : Initialize the snic interface.
 */
static int
snic_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
{
        struct Scsi_Host *shost;
        struct snic *snic;
        mempool_t *pool;
        unsigned long flags;
        u32 max_ios = 0;
        int ret, i;

        /* Device Information */
        SNIC_INFO("snic device %4x:%4x:%4x:%4x: ",
                  pdev->vendor, pdev->device, pdev->subsystem_vendor,
                  pdev->subsystem_device);

        SNIC_INFO("snic device bus %x: slot %x: fn %x\n",
                  pdev->bus->number, PCI_SLOT(pdev->devfn),
                  PCI_FUNC(pdev->devfn));

        /*
         * Allocate SCSI Host and setup association between host, and snic
         */
        shost = scsi_host_alloc(&snic_host_template, sizeof(struct snic));
        if (!shost) {
                SNIC_ERR("Unable to alloc scsi_host\n");
                ret = -ENOMEM;

                goto prob_end;
        }
        snic = shost_priv(shost);
        snic->shost = shost;

        snprintf(snic->name, sizeof(snic->name) - 1, "%s%d", SNIC_DRV_NAME,
                 shost->host_no);

        SNIC_HOST_INFO(shost,
                       "snic%d = %p shost = %p device bus %x: slot %x: fn %x\n",
                       shost->host_no, snic, shost, pdev->bus->number,
                       PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn));
#ifdef CONFIG_SCSI_SNIC_DEBUG_FS
        /* Per snic debugfs init */
        ret = snic_stats_debugfs_init(snic);
        if (ret) {
                SNIC_HOST_ERR(snic->shost,
                              "Failed to initialize debugfs stats\n");
                snic_stats_debugfs_remove(snic);
        }
#endif

        /* Setup PCI Resources */
        pci_set_drvdata(pdev, snic);
        snic->pdev = pdev;

        ret = pci_enable_device(pdev);
        if (ret) {
                SNIC_HOST_ERR(shost,
                              "Cannot enable PCI Resources, aborting : %d\n",
                              ret);

                goto err_free_snic;
        }

        ret = pci_request_regions(pdev, SNIC_DRV_NAME);
        if (ret) {
                SNIC_HOST_ERR(shost,
                              "Cannot obtain PCI Resources, aborting : %d\n",
                              ret);

                goto err_pci_disable;
        }

        pci_set_master(pdev);

        /*
         * Query PCI Controller on system for DMA addressing
         * limitation for the device. Try 43-bit first, and
         * fail to 32-bit.
         */
        ret = pci_set_dma_mask(pdev, DMA_BIT_MASK(43));
        if (ret) {
                ret = pci_set_dma_mask(pdev, DMA_BIT_MASK(32));
                if (ret) {
                        SNIC_HOST_ERR(shost,
                                      "No Usable DMA Configuration, aborting %d\n",
                                      ret);

                        goto err_rel_regions;
                }

                ret = pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(32));
                if (ret) {
                        SNIC_HOST_ERR(shost,
                                      "Unable to obtain 32-bit DMA for consistent allocations, aborting: %d\n",
                                      ret);

                        goto err_rel_regions;
                }
        } else {
                ret = pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(43));
                if (ret) {
                        SNIC_HOST_ERR(shost,
                                      "Unable to obtain 43-bit DMA for consistent allocations. aborting: %d\n",
                                      ret);

                        goto err_rel_regions;
                }
        }


        /* Map vNIC resources from BAR0 */
        if (!(pci_resource_flags(pdev, 0) & IORESOURCE_MEM)) {
                SNIC_HOST_ERR(shost, "BAR0 not memory mappable aborting.\n");

                ret = -ENODEV;
                goto err_rel_regions;
        }

        snic->bar0.vaddr = pci_iomap(pdev, 0, 0);
        if (!snic->bar0.vaddr) {
                SNIC_HOST_ERR(shost,
                              "Cannot memory map BAR0 res hdr aborting.\n");

                ret = -ENODEV;
                goto err_rel_regions;
        }

        snic->bar0.bus_addr = pci_resource_start(pdev, 0);
        snic->bar0.len = pci_resource_len(pdev, 0);
        SNIC_BUG_ON(snic->bar0.bus_addr == 0);

        /* Devcmd2 Resource Allocation and Initialization */
        snic->vdev = svnic_dev_alloc_discover(NULL, snic, pdev, &snic->bar0, 1);
        if (!snic->vdev) {
                SNIC_HOST_ERR(shost, "vNIC Resource Discovery Failed.\n");

                ret = -ENODEV;
                goto err_iounmap;
        }

        ret = svnic_dev_cmd_init(snic->vdev, 0);
        if (ret) {
                SNIC_HOST_INFO(shost, "Devcmd2 Init Failed. err = %d\n", ret);

                goto err_vnic_unreg;
        }

        ret = snic_dev_wait(snic->vdev, svnic_dev_open, snic_vdev_open_done, 0);
        if (ret) {
                SNIC_HOST_ERR(shost,
                              "vNIC dev open failed, aborting. %d\n",
                              ret);

                goto err_vnic_unreg;
        }

        ret = svnic_dev_init(snic->vdev, 0);
        if (ret) {
                SNIC_HOST_ERR(shost,
                              "vNIC dev init failed. aborting. %d\n",
                              ret);

                goto err_dev_close;
        }

        /* Get vNIC information */
        ret = snic_get_vnic_config(snic);
        if (ret) {
                SNIC_HOST_ERR(shost,
                              "Get vNIC configuration failed, aborting. %d\n",
                              ret);

                goto err_dev_close;
        }

        /* Configure Maximum Outstanding IO reqs */
        max_ios = snic->config.io_throttle_count;
        if (max_ios != SNIC_UCSM_DFLT_THROTTLE_CNT_BLD)
                shost->can_queue = min_t(u32, SNIC_MAX_IO_REQ,
                                         max_t(u32, SNIC_MIN_IO_REQ, max_ios));

        snic->max_tag_id = shost->can_queue;

        shost->max_lun = snic->config.luns_per_tgt;
        shost->max_id = SNIC_MAX_TARGET;

        shost->max_cmd_len = MAX_COMMAND_SIZE; /*defined in scsi_cmnd.h*/

        snic_get_res_counts(snic);

        /*
         * Assumption: Only MSIx is supported
         */
        ret = snic_set_intr_mode(snic);
        if (ret) {
                SNIC_HOST_ERR(shost,
                              "Failed to set intr mode aborting. %d\n",
                              ret);

                goto err_dev_close;
        }

        ret = snic_alloc_vnic_res(snic);
        if (ret) {
                SNIC_HOST_ERR(shost,
                              "Failed to alloc vNIC resources aborting. %d\n",
                              ret);

                goto err_clear_intr;
        }

        /* Initialize specific lists */
        INIT_LIST_HEAD(&snic->list);

        /*
         * spl_cmd_list for maintaining snic specific cmds
         * such as EXCH_VER_REQ, REPORT_TARGETS etc
         */
        INIT_LIST_HEAD(&snic->spl_cmd_list);
        spin_lock_init(&snic->spl_cmd_lock);

        /* initialize all snic locks */
        spin_lock_init(&snic->snic_lock);

        for (i = 0; i < SNIC_WQ_MAX; i++)
                spin_lock_init(&snic->wq_lock[i]);

        for (i = 0; i < SNIC_IO_LOCKS; i++)
                spin_lock_init(&snic->io_req_lock[i]);

        pool = mempool_create_slab_pool(2,
                                snic_glob->req_cache[SNIC_REQ_CACHE_DFLT_SGL]);
        if (!pool) {
                SNIC_HOST_ERR(shost, "dflt sgl pool creation failed\n");

                ret = -ENOMEM;
                goto err_free_res;
        }

        snic->req_pool[SNIC_REQ_CACHE_DFLT_SGL] = pool;

        pool = mempool_create_slab_pool(2,
                                snic_glob->req_cache[SNIC_REQ_CACHE_MAX_SGL]);
        if (!pool) {
                SNIC_HOST_ERR(shost, "max sgl pool creation failed\n");

                ret = -ENOMEM;
                goto err_free_dflt_sgl_pool;
        }

        snic->req_pool[SNIC_REQ_CACHE_MAX_SGL] = pool;

        pool = mempool_create_slab_pool(2,
                                snic_glob->req_cache[SNIC_REQ_TM_CACHE]);
        if (!pool) {
                SNIC_HOST_ERR(shost, "snic tmreq info pool creation failed.\n");

                ret = -ENOMEM;
                goto err_free_max_sgl_pool;
        }

        snic->req_pool[SNIC_REQ_TM_CACHE] = pool;

        /* Initialize snic state */
        atomic_set(&snic->state, SNIC_INIT);

        atomic_set(&snic->ios_inflight, 0);

        /* Setup notification buffer area */
        ret = snic_notify_set(snic);
        if (ret) {
                SNIC_HOST_ERR(shost,
                              "Failed to alloc notify buffer aborting. %d\n",
                              ret);

                goto err_free_tmreq_pool;
        }

        spin_lock_irqsave(&snic_glob->snic_list_lock, flags);
        list_add_tail(&snic->list, &snic_glob->snic_list);
        spin_unlock_irqrestore(&snic_glob->snic_list_lock, flags);

        snic_disc_init(&snic->disc);
        INIT_WORK(&snic->tgt_work, snic_handle_tgt_disc);
        INIT_WORK(&snic->disc_work, snic_handle_disc);
        INIT_WORK(&snic->link_work, snic_handle_link);

        /* Enable all queues */
        for (i = 0; i < snic->wq_count; i++)
                svnic_wq_enable(&snic->wq[i]);

        ret = svnic_dev_enable_wait(snic->vdev);
        if (ret) {
                SNIC_HOST_ERR(shost,
                              "vNIC dev enable failed w/ error %d\n",
                              ret);

                goto err_vdev_enable;
        }

        ret = snic_request_intr(snic);
        if (ret) {
                SNIC_HOST_ERR(shost, "Unable to request irq. %d\n", ret);

                goto err_req_intr;
        }

        for (i = 0; i < snic->intr_count; i++)
                svnic_intr_unmask(&snic->intr[i]);

        /* Get snic params */
        ret = snic_get_conf(snic);
        if (ret) {
                SNIC_HOST_ERR(shost,
                              "Failed to get snic io config from FW w err %d\n",
                              ret);

                goto err_get_conf;
        }

        /*
         * Initialization done with PCI system, hardware, firmware.
         * Add shost to SCSI
         */
        ret = snic_add_host(shost, pdev);
        if (ret) {
                SNIC_HOST_ERR(shost,
                              "Adding scsi host Failed ... exiting. %d\n",
                              ret);

                goto err_get_conf;
        }

        snic_set_state(snic, SNIC_ONLINE);

        ret = snic_disc_start(snic);
        if (ret) {
                SNIC_HOST_ERR(shost, "snic_probe:Discovery Failed w err = %d\n",
                              ret);

                goto err_get_conf;
        }

        SNIC_HOST_INFO(shost, "SNIC Device Probe Successful.\n");

        return 0;

err_get_conf:
        snic_free_all_untagged_reqs(snic);

        for (i = 0; i < snic->intr_count; i++)
                svnic_intr_mask(&snic->intr[i]);

        snic_free_intr(snic);

err_req_intr:
        svnic_dev_disable(snic->vdev);

err_vdev_enable:
        svnic_dev_notify_unset(snic->vdev);

        for (i = 0; i < snic->wq_count; i++) {
                int rc = 0;

                rc = svnic_wq_disable(&snic->wq[i]);
                if (rc) {
                        SNIC_HOST_ERR(shost,
                                      "WQ Disable Failed w/ err = %d\n", rc);

                         break;
                }
        }
        snic_del_host(snic->shost);

err_free_tmreq_pool:
        mempool_destroy(snic->req_pool[SNIC_REQ_TM_CACHE]);

err_free_max_sgl_pool:
        mempool_destroy(snic->req_pool[SNIC_REQ_CACHE_MAX_SGL]);

err_free_dflt_sgl_pool:
        mempool_destroy(snic->req_pool[SNIC_REQ_CACHE_DFLT_SGL]);

err_free_res:
        snic_free_vnic_res(snic);

err_clear_intr:
        snic_clear_intr_mode(snic);

err_dev_close:
        svnic_dev_close(snic->vdev);

err_vnic_unreg:
        svnic_dev_unregister(snic->vdev);

err_iounmap:
        snic_iounmap(snic);

err_rel_regions:
        pci_release_regions(pdev);

err_pci_disable:
        pci_disable_device(pdev);

err_free_snic:
#ifdef CONFIG_SCSI_SNIC_DEBUG_FS
        snic_stats_debugfs_remove(snic);
#endif
        scsi_host_put(shost);
        pci_set_drvdata(pdev, NULL);

prob_end:
        SNIC_INFO("sNIC device : bus %d: slot %d: fn %d Registration Failed.\n",
                  pdev->bus->number, PCI_SLOT(pdev->devfn),
                  PCI_FUNC(pdev->devfn));

        return ret;
} /* end of snic_probe */


/*
 * snic_remove : invoked on unbinding the interface to cleanup the
 * resources allocated in snic_probe on initialization.
 */
static void
snic_remove(struct pci_dev *pdev)
{
        struct snic *snic = pci_get_drvdata(pdev);
        unsigned long flags;

        if (!snic) {
                SNIC_INFO("sNIC dev: bus %d slot %d fn %d snic inst is null.\n",
                          pdev->bus->number, PCI_SLOT(pdev->devfn),
                          PCI_FUNC(pdev->devfn));

                return;
        }

        /*
         * Mark state so that the workqueue thread stops forwarding
         * received frames and link events. ISR and other threads
         * that can queue work items will also stop creating work
         * items on the snic workqueue
         */
        snic_set_state(snic, SNIC_OFFLINE);
        spin_lock_irqsave(&snic->snic_lock, flags);
        snic->stop_link_events = 1;
        spin_unlock_irqrestore(&snic->snic_lock, flags);

        flush_workqueue(snic_glob->event_q);
        snic_disc_term(snic);

        spin_lock_irqsave(&snic->snic_lock, flags);
        snic->in_remove = 1;
        spin_unlock_irqrestore(&snic->snic_lock, flags);

        /*
         * This stops the snic device, masks all interrupts, Completed
         * CQ entries are drained. Posted WQ/RQ/Copy-WQ entries are
         * cleanup
         */
        snic_cleanup(snic);

        spin_lock_irqsave(&snic_glob->snic_list_lock, flags);
        list_del(&snic->list);
        spin_unlock_irqrestore(&snic_glob->snic_list_lock, flags);

        snic_tgt_del_all(snic);
#ifdef CONFIG_SCSI_SNIC_DEBUG_FS
        snic_stats_debugfs_remove(snic);
#endif
        snic_del_host(snic->shost);

        svnic_dev_notify_unset(snic->vdev);
        snic_free_intr(snic);
        snic_free_vnic_res(snic);
        snic_clear_intr_mode(snic);
        svnic_dev_close(snic->vdev);
        svnic_dev_unregister(snic->vdev);
        snic_iounmap(snic);
        pci_release_regions(pdev);
        pci_disable_device(pdev);
        pci_set_drvdata(pdev, NULL);

        /* this frees Scsi_Host and snic memory (continuous chunk) */
        scsi_host_put(snic->shost);
} /* end of snic_remove */


struct snic_global *snic_glob;

/*
 * snic_global_data_init: Initialize SNIC Global Data
 * Notes: All the global lists, variables should be part of global data
 * this helps in debugging.
 */
static int
snic_global_data_init(void)
{
        int ret = 0;
        struct kmem_cache *cachep;
        ssize_t len = 0;

        snic_glob = kzalloc(sizeof(*snic_glob), GFP_KERNEL);

        if (!snic_glob) {
                SNIC_ERR("Failed to allocate Global Context.\n");

                ret = -ENOMEM;
                goto gdi_end;
        }

#ifdef CONFIG_SCSI_SNIC_DEBUG_FS
        /* Debugfs related Initialization */
        /* Create debugfs entries for snic */
        ret = snic_debugfs_init();
        if (ret < 0) {
                SNIC_ERR("Failed to create sysfs dir for tracing and stats.\n");
                snic_debugfs_term();
                /* continue even if it fails */
        }

        /* Trace related Initialization */
        /* Allocate memory for trace buffer */
        ret = snic_trc_init();
        if (ret < 0) {
                SNIC_ERR("Trace buffer init failed, SNIC tracing disabled\n");
                snic_trc_free();
                /* continue even if it fails */
        }

#endif
        INIT_LIST_HEAD(&snic_glob->snic_list);
        spin_lock_init(&snic_glob->snic_list_lock);

        /* Create a cache for allocation of snic_host_req+default size ESGLs */
        len = sizeof(struct snic_req_info);
        len += sizeof(struct snic_host_req) + sizeof(struct snic_dflt_sgl);
        cachep = kmem_cache_create("snic_req_dfltsgl", len, SNIC_SG_DESC_ALIGN,
                                   SLAB_HWCACHE_ALIGN, NULL);
        if (!cachep) {
                SNIC_ERR("Failed to create snic default sgl slab\n");
                ret = -ENOMEM;

                goto err_dflt_req_slab;
        }
        snic_glob->req_cache[SNIC_REQ_CACHE_DFLT_SGL] = cachep;

        /* Create a cache for allocation of max size Extended SGLs */
        len = sizeof(struct snic_req_info);
        len += sizeof(struct snic_host_req) + sizeof(struct snic_max_sgl);
        cachep = kmem_cache_create("snic_req_maxsgl", len, SNIC_SG_DESC_ALIGN,
                                   SLAB_HWCACHE_ALIGN, NULL);
        if (!cachep) {
                SNIC_ERR("Failed to create snic max sgl slab\n");
                ret = -ENOMEM;

                goto err_max_req_slab;
        }
        snic_glob->req_cache[SNIC_REQ_CACHE_MAX_SGL] = cachep;

        len = sizeof(struct snic_host_req);
        cachep = kmem_cache_create("snic_req_maxsgl", len, SNIC_SG_DESC_ALIGN,
                                   SLAB_HWCACHE_ALIGN, NULL);
        if (!cachep) {
                SNIC_ERR("Failed to create snic tm req slab\n");
                ret = -ENOMEM;

                goto err_tmreq_slab;
        }
        snic_glob->req_cache[SNIC_REQ_TM_CACHE] = cachep;

        /* snic_event queue */
        snic_glob->event_q = create_singlethread_workqueue("snic_event_wq");
        if (!snic_glob->event_q) {
                SNIC_ERR("snic event queue create failed\n");
                ret = -ENOMEM;

                goto err_eventq;
        }

        return ret;

err_eventq:
        kmem_cache_destroy(snic_glob->req_cache[SNIC_REQ_TM_CACHE]);

err_tmreq_slab:
        kmem_cache_destroy(snic_glob->req_cache[SNIC_REQ_CACHE_MAX_SGL]);

err_max_req_slab:
        kmem_cache_destroy(snic_glob->req_cache[SNIC_REQ_CACHE_DFLT_SGL]);

err_dflt_req_slab:
#ifdef CONFIG_SCSI_SNIC_DEBUG_FS
        snic_trc_free();
        snic_debugfs_term();
#endif
        kfree(snic_glob);
        snic_glob = NULL;

gdi_end:
        return ret;
} /* end of snic_glob_init */

/*
 * snic_global_data_cleanup : Frees SNIC Global Data
 */
static void
snic_global_data_cleanup(void)
{
        SNIC_BUG_ON(snic_glob == NULL);

        destroy_workqueue(snic_glob->event_q);
        kmem_cache_destroy(snic_glob->req_cache[SNIC_REQ_TM_CACHE]);
        kmem_cache_destroy(snic_glob->req_cache[SNIC_REQ_CACHE_MAX_SGL]);
        kmem_cache_destroy(snic_glob->req_cache[SNIC_REQ_CACHE_DFLT_SGL]);

#ifdef CONFIG_SCSI_SNIC_DEBUG_FS
        /* Freeing Trace Resources */
        snic_trc_free();

        /* Freeing Debugfs Resources */
        snic_debugfs_term();
#endif
        kfree(snic_glob);
        snic_glob = NULL;
} /* end of snic_glob_cleanup */

static struct pci_driver snic_driver = {
        .name = SNIC_DRV_NAME,
        .id_table = snic_id_table,
        .probe = snic_probe,
        .remove = snic_remove,
};

static int __init
snic_init_module(void)
{
        int ret = 0;

#ifndef __x86_64__
        SNIC_INFO("SNIC Driver is supported only for x86_64 platforms!\n");

        add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
#endif

        SNIC_INFO("%s, ver %s\n", SNIC_DRV_DESCRIPTION, SNIC_DRV_VERSION);

        ret = snic_global_data_init();
        if (ret) {
                SNIC_ERR("Failed to Initialize Global Data.\n");

                return ret;
        }

        ret = pci_register_driver(&snic_driver);
        if (ret < 0) {
                SNIC_ERR("PCI driver register error\n");

                goto err_pci_reg;
        }

        return ret;

err_pci_reg:
        snic_global_data_cleanup();

        return ret;
}

static void __exit
snic_cleanup_module(void)
{
        pci_unregister_driver(&snic_driver);
        snic_global_data_cleanup();
}

module_init(snic_init_module);
module_exit(snic_cleanup_module);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION(SNIC_DRV_DESCRIPTION);
MODULE_VERSION(SNIC_DRV_VERSION);
MODULE_DEVICE_TABLE(pci, snic_id_table);
MODULE_AUTHOR("Narsimhulu Musini <nmusini@cisco.com>, "
              "Sesidhar Baddela <sebaddel@cisco.com>");