/*
 * Linux driver for VMware's para-virtualized SCSI HBA.
 *
 * Copyright (C) 2008-2014, VMware, Inc. All Rights Reserved.
 *
 * This program is free software; you can 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 and no later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/pci.h>

#include <scsi/scsi.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_tcq.h>

#include "vmw_pvscsi.h"

#define PVSCSI_LINUX_DRIVER_DESC "VMware PVSCSI driver"

MODULE_DESCRIPTION(PVSCSI_LINUX_DRIVER_DESC);
MODULE_AUTHOR("VMware, Inc.");
MODULE_LICENSE("GPL");
MODULE_VERSION(PVSCSI_DRIVER_VERSION_STRING);

#define PVSCSI_DEFAULT_NUM_PAGES_PER_RING       8
#define PVSCSI_DEFAULT_NUM_PAGES_MSG_RING       1
#define PVSCSI_DEFAULT_QUEUE_DEPTH              254
#define SGL_SIZE                                PAGE_SIZE

struct pvscsi_sg_list {
        struct PVSCSISGElement sge[PVSCSI_MAX_NUM_SG_ENTRIES_PER_SEGMENT];
};

struct pvscsi_ctx {
        /*
         * The index of the context in cmd_map serves as the context ID for a
         * 1-to-1 mapping completions back to requests.
         */
        struct scsi_cmnd        *cmd;
        struct pvscsi_sg_list   *sgl;
        struct list_head        list;
        dma_addr_t              dataPA;
        dma_addr_t              sensePA;
        dma_addr_t              sglPA;
        struct completion       *abort_cmp;
};

struct pvscsi_adapter {
        char                            *mmioBase;
        u8                              rev;
        bool                            use_msg;
        bool                            use_req_threshold;

        spinlock_t                      hw_lock;

        struct workqueue_struct         *workqueue;
        struct work_struct              work;

        struct PVSCSIRingReqDesc        *req_ring;
        unsigned                        req_pages;
        unsigned                        req_depth;
        dma_addr_t                      reqRingPA;

        struct PVSCSIRingCmpDesc        *cmp_ring;
        unsigned                        cmp_pages;
        dma_addr_t                      cmpRingPA;

        struct PVSCSIRingMsgDesc        *msg_ring;
        unsigned                        msg_pages;
        dma_addr_t                      msgRingPA;

        struct PVSCSIRingsState         *rings_state;
        dma_addr_t                      ringStatePA;

        struct pci_dev                  *dev;
        struct Scsi_Host                *host;

        struct list_head                cmd_pool;
        struct pvscsi_ctx               *cmd_map;
};


/* Command line parameters */
static int pvscsi_ring_pages;
static int pvscsi_msg_ring_pages = PVSCSI_DEFAULT_NUM_PAGES_MSG_RING;
static int pvscsi_cmd_per_lun    = PVSCSI_DEFAULT_QUEUE_DEPTH;
static bool pvscsi_disable_msi;
static bool pvscsi_disable_msix;
static bool pvscsi_use_msg       = true;
static bool pvscsi_use_req_threshold = true;

#define PVSCSI_RW (S_IRUSR | S_IWUSR)

module_param_named(ring_pages, pvscsi_ring_pages, int, PVSCSI_RW);
MODULE_PARM_DESC(ring_pages, "Number of pages per req/cmp ring - (default="
                 __stringify(PVSCSI_DEFAULT_NUM_PAGES_PER_RING)
                 "[up to 16 targets],"
                 __stringify(PVSCSI_SETUP_RINGS_MAX_NUM_PAGES)
                 "[for 16+ targets])");

module_param_named(msg_ring_pages, pvscsi_msg_ring_pages, int, PVSCSI_RW);
MODULE_PARM_DESC(msg_ring_pages, "Number of pages for the msg ring - (default="
                 __stringify(PVSCSI_DEFAULT_NUM_PAGES_MSG_RING) ")");

module_param_named(cmd_per_lun, pvscsi_cmd_per_lun, int, PVSCSI_RW);
MODULE_PARM_DESC(cmd_per_lun, "Maximum commands per lun - (default="
                 __stringify(PVSCSI_DEFAULT_QUEUE_DEPTH) ")");

module_param_named(disable_msi, pvscsi_disable_msi, bool, PVSCSI_RW);
MODULE_PARM_DESC(disable_msi, "Disable MSI use in driver - (default=0)");

module_param_named(disable_msix, pvscsi_disable_msix, bool, PVSCSI_RW);
MODULE_PARM_DESC(disable_msix, "Disable MSI-X use in driver - (default=0)");

module_param_named(use_msg, pvscsi_use_msg, bool, PVSCSI_RW);
MODULE_PARM_DESC(use_msg, "Use msg ring when available - (default=1)");

module_param_named(use_req_threshold, pvscsi_use_req_threshold,
                   bool, PVSCSI_RW);
MODULE_PARM_DESC(use_req_threshold, "Use driver-based request coalescing if configured - (default=1)");

static const struct pci_device_id pvscsi_pci_tbl[] = {
        { PCI_VDEVICE(VMWARE, PCI_DEVICE_ID_VMWARE_PVSCSI) },
        { 0 }
};

MODULE_DEVICE_TABLE(pci, pvscsi_pci_tbl);

static struct device *
pvscsi_dev(const struct pvscsi_adapter *adapter)
{
        return &(adapter->dev->dev);
}

static struct pvscsi_ctx *
pvscsi_find_context(const struct pvscsi_adapter *adapter, struct scsi_cmnd *cmd)
{
        struct pvscsi_ctx *ctx, *end;

        end = &adapter->cmd_map[adapter->req_depth];
        for (ctx = adapter->cmd_map; ctx < end; ctx++)
                if (ctx->cmd == cmd)
                        return ctx;

        return NULL;
}

static struct pvscsi_ctx *
pvscsi_acquire_context(struct pvscsi_adapter *adapter, struct scsi_cmnd *cmd)
{
        struct pvscsi_ctx *ctx;

        if (list_empty(&adapter->cmd_pool))
                return NULL;

        ctx = list_first_entry(&adapter->cmd_pool, struct pvscsi_ctx, list);
        ctx->cmd = cmd;
        list_del(&ctx->list);

        return ctx;
}

static void pvscsi_release_context(struct pvscsi_adapter *adapter,
                                   struct pvscsi_ctx *ctx)
{
        ctx->cmd = NULL;
        ctx->abort_cmp = NULL;
        list_add(&ctx->list, &adapter->cmd_pool);
}

/*
 * Map a pvscsi_ctx struct to a context ID field value; we map to a simple
 * non-zero integer. ctx always points to an entry in cmd_map array, hence
 * the return value is always >=1.
 */
static u64 pvscsi_map_context(const struct pvscsi_adapter *adapter,
                              const struct pvscsi_ctx *ctx)
{
        return ctx - adapter->cmd_map + 1;
}

static struct pvscsi_ctx *
pvscsi_get_context(const struct pvscsi_adapter *adapter, u64 context)
{
        return &adapter->cmd_map[context - 1];
}

static void pvscsi_reg_write(const struct pvscsi_adapter *adapter,
                             u32 offset, u32 val)
{
        writel(val, adapter->mmioBase + offset);
}

static u32 pvscsi_reg_read(const struct pvscsi_adapter *adapter, u32 offset)
{
        return readl(adapter->mmioBase + offset);
}

static u32 pvscsi_read_intr_status(const struct pvscsi_adapter *adapter)
{
        return pvscsi_reg_read(adapter, PVSCSI_REG_OFFSET_INTR_STATUS);
}

static void pvscsi_write_intr_status(const struct pvscsi_adapter *adapter,
                                     u32 val)
{
        pvscsi_reg_write(adapter, PVSCSI_REG_OFFSET_INTR_STATUS, val);
}

static void pvscsi_unmask_intr(const struct pvscsi_adapter *adapter)
{
        u32 intr_bits;

        intr_bits = PVSCSI_INTR_CMPL_MASK;
        if (adapter->use_msg)
                intr_bits |= PVSCSI_INTR_MSG_MASK;

        pvscsi_reg_write(adapter, PVSCSI_REG_OFFSET_INTR_MASK, intr_bits);
}

static void pvscsi_mask_intr(const struct pvscsi_adapter *adapter)
{
        pvscsi_reg_write(adapter, PVSCSI_REG_OFFSET_INTR_MASK, 0);
}

static void pvscsi_write_cmd_desc(const struct pvscsi_adapter *adapter,
                                  u32 cmd, const void *desc, size_t len)
{
        const u32 *ptr = desc;
        size_t i;

        len /= sizeof(*ptr);
        pvscsi_reg_write(adapter, PVSCSI_REG_OFFSET_COMMAND, cmd);
        for (i = 0; i < len; i++)
                pvscsi_reg_write(adapter,
                                 PVSCSI_REG_OFFSET_COMMAND_DATA, ptr[i]);
}

static void pvscsi_abort_cmd(const struct pvscsi_adapter *adapter,
                             const struct pvscsi_ctx *ctx)
{
        struct PVSCSICmdDescAbortCmd cmd = { 0 };

        cmd.target = ctx->cmd->device->id;
        cmd.context = pvscsi_map_context(adapter, ctx);

        pvscsi_write_cmd_desc(adapter, PVSCSI_CMD_ABORT_CMD, &cmd, sizeof(cmd));
}

static void pvscsi_kick_rw_io(const struct pvscsi_adapter *adapter)
{
        pvscsi_reg_write(adapter, PVSCSI_REG_OFFSET_KICK_RW_IO, 0);
}

static void pvscsi_process_request_ring(const struct pvscsi_adapter *adapter)
{
        pvscsi_reg_write(adapter, PVSCSI_REG_OFFSET_KICK_NON_RW_IO, 0);
}

static int scsi_is_rw(unsigned char op)
{
        return op == READ_6  || op == WRITE_6 ||
               op == READ_10 || op == WRITE_10 ||
               op == READ_12 || op == WRITE_12 ||
               op == READ_16 || op == WRITE_16;
}

static void pvscsi_kick_io(const struct pvscsi_adapter *adapter,
                           unsigned char op)
{
        if (scsi_is_rw(op)) {
                struct PVSCSIRingsState *s = adapter->rings_state;

                if (!adapter->use_req_threshold ||
                    s->reqProdIdx - s->reqConsIdx >= s->reqCallThreshold)
                        pvscsi_kick_rw_io(adapter);
        } else {
                pvscsi_process_request_ring(adapter);
        }
}

static void ll_adapter_reset(const struct pvscsi_adapter *adapter)
{
        dev_dbg(pvscsi_dev(adapter), "Adapter Reset on %p\n", adapter);

        pvscsi_write_cmd_desc(adapter, PVSCSI_CMD_ADAPTER_RESET, NULL, 0);
}

static void ll_bus_reset(const struct pvscsi_adapter *adapter)
{
        dev_dbg(pvscsi_dev(adapter), "Resetting bus on %p\n", adapter);

        pvscsi_write_cmd_desc(adapter, PVSCSI_CMD_RESET_BUS, NULL, 0);
}

static void ll_device_reset(const struct pvscsi_adapter *adapter, u32 target)
{
        struct PVSCSICmdDescResetDevice cmd = { 0 };

        dev_dbg(pvscsi_dev(adapter), "Resetting device: target=%u\n", target);

        cmd.target = target;

        pvscsi_write_cmd_desc(adapter, PVSCSI_CMD_RESET_DEVICE,
                              &cmd, sizeof(cmd));
}

static void pvscsi_create_sg(struct pvscsi_ctx *ctx,
                             struct scatterlist *sg, unsigned count)
{
        unsigned i;
        struct PVSCSISGElement *sge;

        BUG_ON(count > PVSCSI_MAX_NUM_SG_ENTRIES_PER_SEGMENT);

        sge = &ctx->sgl->sge[0];
        for (i = 0; i < count; i++, sg = sg_next(sg)) {
                sge[i].addr   = sg_dma_address(sg);
                sge[i].length = sg_dma_len(sg);
                sge[i].flags  = 0;
        }
}

/*
 * Map all data buffers for a command into PCI space and
 * setup the scatter/gather list if needed.
 */
static int pvscsi_map_buffers(struct pvscsi_adapter *adapter,
                              struct pvscsi_ctx *ctx, struct scsi_cmnd *cmd,
                              struct PVSCSIRingReqDesc *e)
{
        unsigned count;
        unsigned bufflen = scsi_bufflen(cmd);
        struct scatterlist *sg;

        e->dataLen = bufflen;
        e->dataAddr = 0;
        if (bufflen == 0)
                return 0;

        sg = scsi_sglist(cmd);
        count = scsi_sg_count(cmd);
        if (count != 0) {
                int segs = scsi_dma_map(cmd);

                if (segs == -ENOMEM) {
                        scmd_printk(KERN_DEBUG, cmd,
                                    "vmw_pvscsi: Failed to map cmd sglist for DMA.\n");
                        return -ENOMEM;
                } else if (segs > 1) {
                        pvscsi_create_sg(ctx, sg, segs);

                        e->flags |= PVSCSI_FLAG_CMD_WITH_SG_LIST;
                        ctx->sglPA = dma_map_single(&adapter->dev->dev,
                                        ctx->sgl, SGL_SIZE, DMA_TO_DEVICE);
                        if (dma_mapping_error(&adapter->dev->dev, ctx->sglPA)) {
                                scmd_printk(KERN_ERR, cmd,
                                            "vmw_pvscsi: Failed to map ctx sglist for DMA.\n");
                                scsi_dma_unmap(cmd);
                                ctx->sglPA = 0;
                                return -ENOMEM;
                        }
                        e->dataAddr = ctx->sglPA;
                } else
                        e->dataAddr = sg_dma_address(sg);
        } else {
                /*
                 * In case there is no S/G list, scsi_sglist points
                 * directly to the buffer.
                 */
                ctx->dataPA = dma_map_single(&adapter->dev->dev, sg, bufflen,
                                             cmd->sc_data_direction);
                if (dma_mapping_error(&adapter->dev->dev, ctx->dataPA)) {
                        scmd_printk(KERN_DEBUG, cmd,
                                    "vmw_pvscsi: Failed to map direct data buffer for DMA.\n");
                        return -ENOMEM;
                }
                e->dataAddr = ctx->dataPA;
        }

        return 0;
}

/*
 * The device incorrectly doesn't clear the first byte of the sense
 * buffer in some cases. We have to do it ourselves.
 * Otherwise we run into trouble when SWIOTLB is forced.
 */
static void pvscsi_patch_sense(struct scsi_cmnd *cmd)
{
        if (cmd->sense_buffer)
                cmd->sense_buffer[0] = 0;
}

static void pvscsi_unmap_buffers(const struct pvscsi_adapter *adapter,
                                 struct pvscsi_ctx *ctx)
{
        struct scsi_cmnd *cmd;
        unsigned bufflen;

        cmd = ctx->cmd;
        bufflen = scsi_bufflen(cmd);

        if (bufflen != 0) {
                unsigned count = scsi_sg_count(cmd);

                if (count != 0) {
                        scsi_dma_unmap(cmd);
                        if (ctx->sglPA) {
                                dma_unmap_single(&adapter->dev->dev, ctx->sglPA,
                                                 SGL_SIZE, DMA_TO_DEVICE);
                                ctx->sglPA = 0;
                        }
                } else
                        dma_unmap_single(&adapter->dev->dev, ctx->dataPA,
                                         bufflen, cmd->sc_data_direction);
        }
        if (cmd->sense_buffer)
                dma_unmap_single(&adapter->dev->dev, ctx->sensePA,
                                 SCSI_SENSE_BUFFERSIZE, DMA_FROM_DEVICE);
}

static int pvscsi_allocate_rings(struct pvscsi_adapter *adapter)
{
        adapter->rings_state = dma_alloc_coherent(&adapter->dev->dev, PAGE_SIZE,
                        &adapter->ringStatePA, GFP_KERNEL);
        if (!adapter->rings_state)
                return -ENOMEM;

        adapter->req_pages = min(PVSCSI_MAX_NUM_PAGES_REQ_RING,
                                 pvscsi_ring_pages);
        adapter->req_depth = adapter->req_pages
                                        * PVSCSI_MAX_NUM_REQ_ENTRIES_PER_PAGE;
        adapter->req_ring = dma_alloc_coherent(&adapter->dev->dev,
                        adapter->req_pages * PAGE_SIZE, &adapter->reqRingPA,
                        GFP_KERNEL);
        if (!adapter->req_ring)
                return -ENOMEM;

        adapter->cmp_pages = min(PVSCSI_MAX_NUM_PAGES_CMP_RING,
                                 pvscsi_ring_pages);
        adapter->cmp_ring = dma_alloc_coherent(&adapter->dev->dev,
                        adapter->cmp_pages * PAGE_SIZE, &adapter->cmpRingPA,
                        GFP_KERNEL);
        if (!adapter->cmp_ring)
                return -ENOMEM;

        BUG_ON(!IS_ALIGNED(adapter->ringStatePA, PAGE_SIZE));
        BUG_ON(!IS_ALIGNED(adapter->reqRingPA, PAGE_SIZE));
        BUG_ON(!IS_ALIGNED(adapter->cmpRingPA, PAGE_SIZE));

        if (!adapter->use_msg)
                return 0;

        adapter->msg_pages = min(PVSCSI_MAX_NUM_PAGES_MSG_RING,
                                 pvscsi_msg_ring_pages);
        adapter->msg_ring = dma_alloc_coherent(&adapter->dev->dev,
                        adapter->msg_pages * PAGE_SIZE, &adapter->msgRingPA,
                        GFP_KERNEL);
        if (!adapter->msg_ring)
                return -ENOMEM;
        BUG_ON(!IS_ALIGNED(adapter->msgRingPA, PAGE_SIZE));

        return 0;
}

static void pvscsi_setup_all_rings(const struct pvscsi_adapter *adapter)
{
        struct PVSCSICmdDescSetupRings cmd = { 0 };
        dma_addr_t base;
        unsigned i;

        cmd.ringsStatePPN   = adapter->ringStatePA >> PAGE_SHIFT;
        cmd.reqRingNumPages = adapter->req_pages;
        cmd.cmpRingNumPages = adapter->cmp_pages;

        base = adapter->reqRingPA;
        for (i = 0; i < adapter->req_pages; i++) {
                cmd.reqRingPPNs[i] = base >> PAGE_SHIFT;
                base += PAGE_SIZE;
        }

        base = adapter->cmpRingPA;
        for (i = 0; i < adapter->cmp_pages; i++) {
                cmd.cmpRingPPNs[i] = base >> PAGE_SHIFT;
                base += PAGE_SIZE;
        }

        memset(adapter->rings_state, 0, PAGE_SIZE);
        memset(adapter->req_ring, 0, adapter->req_pages * PAGE_SIZE);
        memset(adapter->cmp_ring, 0, adapter->cmp_pages * PAGE_SIZE);

        pvscsi_write_cmd_desc(adapter, PVSCSI_CMD_SETUP_RINGS,
                              &cmd, sizeof(cmd));

        if (adapter->use_msg) {
                struct PVSCSICmdDescSetupMsgRing cmd_msg = { 0 };

                cmd_msg.numPages = adapter->msg_pages;

                base = adapter->msgRingPA;
                for (i = 0; i < adapter->msg_pages; i++) {
                        cmd_msg.ringPPNs[i] = base >> PAGE_SHIFT;
                        base += PAGE_SIZE;
                }
                memset(adapter->msg_ring, 0, adapter->msg_pages * PAGE_SIZE);

                pvscsi_write_cmd_desc(adapter, PVSCSI_CMD_SETUP_MSG_RING,
                                      &cmd_msg, sizeof(cmd_msg));
        }
}

static int pvscsi_change_queue_depth(struct scsi_device *sdev, int qdepth)
{
        if (!sdev->tagged_supported)
                qdepth = 1;
        return scsi_change_queue_depth(sdev, qdepth);
}

/*
 * Pull a completion descriptor off and pass the completion back
 * to the SCSI mid layer.
 */
static void pvscsi_complete_request(struct pvscsi_adapter *adapter,
                                    const struct PVSCSIRingCmpDesc *e)
{
        struct pvscsi_ctx *ctx;
        struct scsi_cmnd *cmd;
        struct completion *abort_cmp;
        u32 btstat = e->hostStatus;
        u32 sdstat = e->scsiStatus;

        ctx = pvscsi_get_context(adapter, e->context);
        cmd = ctx->cmd;
        abort_cmp = ctx->abort_cmp;
        pvscsi_unmap_buffers(adapter, ctx);
        if (sdstat != SAM_STAT_CHECK_CONDITION)
                pvscsi_patch_sense(cmd);
        pvscsi_release_context(adapter, ctx);
        if (abort_cmp) {
                /*
                 * The command was requested to be aborted. Just signal that
                 * the request completed and swallow the actual cmd completion
                 * here. The abort handler will post a completion for this
                 * command indicating that it got successfully aborted.
                 */
                complete(abort_cmp);
                return;
        }

        cmd->result = 0;
        if (sdstat != SAM_STAT_GOOD &&
            (btstat == BTSTAT_SUCCESS ||
             btstat == BTSTAT_LINKED_COMMAND_COMPLETED ||
             btstat == BTSTAT_LINKED_COMMAND_COMPLETED_WITH_FLAG)) {
                if (sdstat == SAM_STAT_COMMAND_TERMINATED) {
                        cmd->result = (DID_RESET << 16);
                } else {
                        cmd->result = (DID_OK << 16) | sdstat;
                }
        } else
                switch (btstat) {
                case BTSTAT_SUCCESS:
                case BTSTAT_LINKED_COMMAND_COMPLETED:
                case BTSTAT_LINKED_COMMAND_COMPLETED_WITH_FLAG:
                        /*
                         * Commands like INQUIRY may transfer less data than
                         * requested by the initiator via bufflen. Set residual
                         * count to make upper layer aware of the actual amount
                         * of data returned.
                         */
                        scsi_set_resid(cmd, scsi_bufflen(cmd) - e->dataLen);
                        cmd->result = (DID_OK << 16);
                        break;

                case BTSTAT_DATARUN:
                case BTSTAT_DATA_UNDERRUN:
                        /* Report residual data in underruns */
                        scsi_set_resid(cmd, scsi_bufflen(cmd) - e->dataLen);
                        cmd->result = (DID_ERROR << 16);
                        break;

                case BTSTAT_SELTIMEO:
                        /* Our emulation returns this for non-connected devs */
                        cmd->result = (DID_BAD_TARGET << 16);
                        break;

                case BTSTAT_LUNMISMATCH:
                case BTSTAT_TAGREJECT:
                case BTSTAT_BADMSG:
                case BTSTAT_HAHARDWARE:
                case BTSTAT_INVPHASE:
                case BTSTAT_HATIMEOUT:
                case BTSTAT_NORESPONSE:
                case BTSTAT_DISCONNECT:
                case BTSTAT_HASOFTWARE:
                case BTSTAT_BUSFREE:
                case BTSTAT_SENSFAILED:
                        cmd->result |= (DID_ERROR << 16);
                        break;

                case BTSTAT_SENTRST:
                case BTSTAT_RECVRST:
                case BTSTAT_BUSRESET:
                        cmd->result = (DID_RESET << 16);
                        break;

                case BTSTAT_ABORTQUEUE:
                        cmd->result = (DID_BUS_BUSY << 16);
                        break;

                case BTSTAT_SCSIPARITY:
                        cmd->result = (DID_PARITY << 16);
                        break;

                default:
                        cmd->result = (DID_ERROR << 16);
                        scmd_printk(KERN_DEBUG, cmd,
                                    "Unknown completion status: 0x%x\n",
                                    btstat);
        }

        dev_dbg(&cmd->device->sdev_gendev,
                "cmd=%p %x ctx=%p result=0x%x status=0x%x,%x\n",
                cmd, cmd->cmnd[0], ctx, cmd->result, btstat, sdstat);

        cmd->scsi_done(cmd);
}

/*
 * barrier usage : Since the PVSCSI device is emulated, there could be cases
 * where we may want to serialize some accesses between the driver and the
 * emulation layer. We use compiler barriers instead of the more expensive
 * memory barriers because PVSCSI is only supported on X86 which has strong
 * memory access ordering.
 */
static void pvscsi_process_completion_ring(struct pvscsi_adapter *adapter)
{
        struct PVSCSIRingsState *s = adapter->rings_state;
        struct PVSCSIRingCmpDesc *ring = adapter->cmp_ring;
        u32 cmp_entries = s->cmpNumEntriesLog2;

        while (s->cmpConsIdx != s->cmpProdIdx) {
                struct PVSCSIRingCmpDesc *e = ring + (s->cmpConsIdx &
                                                      MASK(cmp_entries));
                /*
                 * This barrier() ensures that *e is not dereferenced while
                 * the device emulation still writes data into the slot.
                 * Since the device emulation advances s->cmpProdIdx only after
                 * updating the slot we want to check it first.
                 */
                barrier();
                pvscsi_complete_request(adapter, e);
                /*
                 * This barrier() ensures that compiler doesn't reorder write
                 * to s->cmpConsIdx before the read of (*e) inside
                 * pvscsi_complete_request. Otherwise, device emulation may
                 * overwrite *e before we had a chance to read it.
                 */
                barrier();
                s->cmpConsIdx++;
        }
}

/*
 * Translate a Linux SCSI request into a request ring entry.
 */
static int pvscsi_queue_ring(struct pvscsi_adapter *adapter,
                             struct pvscsi_ctx *ctx, struct scsi_cmnd *cmd)
{
        struct PVSCSIRingsState *s;
        struct PVSCSIRingReqDesc *e;
        struct scsi_device *sdev;
        u32 req_entries;

        s = adapter->rings_state;
        sdev = cmd->device;
        req_entries = s->reqNumEntriesLog2;

        /*
         * If this condition holds, we might have room on the request ring, but
         * we might not have room on the completion ring for the response.
         * However, we have already ruled out this possibility - we would not
         * have successfully allocated a context if it were true, since we only
         * have one context per request entry.  Check for it anyway, since it
         * would be a serious bug.
         */
        if (s->reqProdIdx - s->cmpConsIdx >= 1 << req_entries) {
                scmd_printk(KERN_ERR, cmd, "vmw_pvscsi: "
                            "ring full: reqProdIdx=%d cmpConsIdx=%d\n",
                            s->reqProdIdx, s->cmpConsIdx);
                return -1;
        }

        e = adapter->req_ring + (s->reqProdIdx & MASK(req_entries));

        e->bus    = sdev->channel;
        e->target = sdev->id;
        memset(e->lun, 0, sizeof(e->lun));
        e->lun[1] = sdev->lun;

        if (cmd->sense_buffer) {
                ctx->sensePA = dma_map_single(&adapter->dev->dev,
                                cmd->sense_buffer, SCSI_SENSE_BUFFERSIZE,
                                DMA_FROM_DEVICE);
                if (dma_mapping_error(&adapter->dev->dev, ctx->sensePA)) {
                        scmd_printk(KERN_DEBUG, cmd,
                                    "vmw_pvscsi: Failed to map sense buffer for DMA.\n");
                        ctx->sensePA = 0;
                        return -ENOMEM;
                }
                e->senseAddr = ctx->sensePA;
                e->senseLen = SCSI_SENSE_BUFFERSIZE;
        } else {
                e->senseLen  = 0;
                e->senseAddr = 0;
        }
        e->cdbLen   = cmd->cmd_len;
        e->vcpuHint = smp_processor_id();
        memcpy(e->cdb, cmd->cmnd, e->cdbLen);

        e->tag = SIMPLE_QUEUE_TAG;

        if (cmd->sc_data_direction == DMA_FROM_DEVICE)
                e->flags = PVSCSI_FLAG_CMD_DIR_TOHOST;
        else if (cmd->sc_data_direction == DMA_TO_DEVICE)
                e->flags = PVSCSI_FLAG_CMD_DIR_TODEVICE;
        else if (cmd->sc_data_direction == DMA_NONE)
                e->flags = PVSCSI_FLAG_CMD_DIR_NONE;
        else
                e->flags = 0;

        if (pvscsi_map_buffers(adapter, ctx, cmd, e) != 0) {
                if (cmd->sense_buffer) {
                        dma_unmap_single(&adapter->dev->dev, ctx->sensePA,
                                         SCSI_SENSE_BUFFERSIZE,
                                         DMA_FROM_DEVICE);
                        ctx->sensePA = 0;
                }
                return -ENOMEM;
        }

        e->context = pvscsi_map_context(adapter, ctx);

        barrier();

        s->reqProdIdx++;

        return 0;
}

static int pvscsi_queue_lck(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *))
{
        struct Scsi_Host *host = cmd->device->host;
        struct pvscsi_adapter *adapter = shost_priv(host);
        struct pvscsi_ctx *ctx;
        unsigned long flags;
        unsigned char op;

        spin_lock_irqsave(&adapter->hw_lock, flags);

        ctx = pvscsi_acquire_context(adapter, cmd);
        if (!ctx || pvscsi_queue_ring(adapter, ctx, cmd) != 0) {
                if (ctx)
                        pvscsi_release_context(adapter, ctx);
                spin_unlock_irqrestore(&adapter->hw_lock, flags);
                return SCSI_MLQUEUE_HOST_BUSY;
        }

        cmd->scsi_done = done;
        op = cmd->cmnd[0];

        dev_dbg(&cmd->device->sdev_gendev,
                "queued cmd %p, ctx %p, op=%x\n", cmd, ctx, op);

        spin_unlock_irqrestore(&adapter->hw_lock, flags);

        pvscsi_kick_io(adapter, op);

        return 0;
}

static DEF_SCSI_QCMD(pvscsi_queue)

static int pvscsi_abort(struct scsi_cmnd *cmd)
{
        struct pvscsi_adapter *adapter = shost_priv(cmd->device->host);
        struct pvscsi_ctx *ctx;
        unsigned long flags;
        int result = SUCCESS;
        DECLARE_COMPLETION_ONSTACK(abort_cmp);
        int done;

        scmd_printk(KERN_DEBUG, cmd, "task abort on host %u, %p\n",
                    adapter->host->host_no, cmd);

        spin_lock_irqsave(&adapter->hw_lock, flags);

        /*
         * Poll the completion ring first - we might be trying to abort
         * a command that is waiting to be dispatched in the completion ring.
         */
        pvscsi_process_completion_ring(adapter);

        /*
         * If there is no context for the command, it either already succeeded
         * or else was never properly issued.  Not our problem.
         */
        ctx = pvscsi_find_context(adapter, cmd);
        if (!ctx) {
                scmd_printk(KERN_DEBUG, cmd, "Failed to abort cmd %p\n", cmd);
                goto out;
        }

        /*
         * Mark that the command has been requested to be aborted and issue
         * the abort.
         */
        ctx->abort_cmp = &abort_cmp;

        pvscsi_abort_cmd(adapter, ctx);
        spin_unlock_irqrestore(&adapter->hw_lock, flags);
        /* Wait for 2 secs for the completion. */
        done = wait_for_completion_timeout(&abort_cmp, msecs_to_jiffies(2000));
        spin_lock_irqsave(&adapter->hw_lock, flags);

        if (!done) {
                /*
                 * Failed to abort the command, unmark the fact that it
                 * was requested to be aborted.
                 */
                ctx->abort_cmp = NULL;
                result = FAILED;
                scmd_printk(KERN_DEBUG, cmd,
                            "Failed to get completion for aborted cmd %p\n",
                            cmd);
                goto out;
        }

        /*
         * Successfully aborted the command.
         */
        cmd->result = (DID_ABORT << 16);
        cmd->scsi_done(cmd);

out:
        spin_unlock_irqrestore(&adapter->hw_lock, flags);
        return result;
}

/*
 * Abort all outstanding requests.  This is only safe to use if the completion
 * ring will never be walked again or the device has been reset, because it
 * destroys the 1-1 mapping between context field passed to emulation and our
 * request structure.
 */
static void pvscsi_reset_all(struct pvscsi_adapter *adapter)
{
        unsigned i;

        for (i = 0; i < adapter->req_depth; i++) {
                struct pvscsi_ctx *ctx = &adapter->cmd_map[i];
                struct scsi_cmnd *cmd = ctx->cmd;
                if (cmd) {
                        scmd_printk(KERN_ERR, cmd,
                                    "Forced reset on cmd %p\n", cmd);
                        pvscsi_unmap_buffers(adapter, ctx);
                        pvscsi_patch_sense(cmd);
                        pvscsi_release_context(adapter, ctx);
                        cmd->result = (DID_RESET << 16);
                        cmd->scsi_done(cmd);
                }
        }
}

static int pvscsi_host_reset(struct scsi_cmnd *cmd)
{
        struct Scsi_Host *host = cmd->device->host;
        struct pvscsi_adapter *adapter = shost_priv(host);
        unsigned long flags;
        bool use_msg;

        scmd_printk(KERN_INFO, cmd, "SCSI Host reset\n");

        spin_lock_irqsave(&adapter->hw_lock, flags);

        use_msg = adapter->use_msg;

        if (use_msg) {
                adapter->use_msg = false;
                spin_unlock_irqrestore(&adapter->hw_lock, flags);

                /*
                 * Now that we know that the ISR won't add more work on the
                 * workqueue we can safely flush any outstanding work.
                 */
                flush_workqueue(adapter->workqueue);
                spin_lock_irqsave(&adapter->hw_lock, flags);
        }

        /*
         * We're going to tear down the entire ring structure and set it back
         * up, so stalling new requests until all completions are flushed and
         * the rings are back in place.
         */

        pvscsi_process_request_ring(adapter);

        ll_adapter_reset(adapter);

        /*
         * Now process any completions.  Note we do this AFTER adapter reset,
         * which is strange, but stops races where completions get posted
         * between processing the ring and issuing the reset.  The backend will
         * not touch the ring memory after reset, so the immediately pre-reset
         * completion ring state is still valid.
         */
        pvscsi_process_completion_ring(adapter);

        pvscsi_reset_all(adapter);
        adapter->use_msg = use_msg;
        pvscsi_setup_all_rings(adapter);
        pvscsi_unmask_intr(adapter);

        spin_unlock_irqrestore(&adapter->hw_lock, flags);

        return SUCCESS;
}

static int pvscsi_bus_reset(struct scsi_cmnd *cmd)
{
        struct Scsi_Host *host = cmd->device->host;
        struct pvscsi_adapter *adapter = shost_priv(host);
        unsigned long flags;

        scmd_printk(KERN_INFO, cmd, "SCSI Bus reset\n");

        /*
         * We don't want to queue new requests for this bus after
         * flushing all pending requests to emulation, since new
         * requests could then sneak in during this bus reset phase,
         * so take the lock now.
         */
        spin_lock_irqsave(&adapter->hw_lock, flags);

        pvscsi_process_request_ring(adapter);
        ll_bus_reset(adapter);
        pvscsi_process_completion_ring(adapter);

        spin_unlock_irqrestore(&adapter->hw_lock, flags);

        return SUCCESS;
}

static int pvscsi_device_reset(struct scsi_cmnd *cmd)
{
        struct Scsi_Host *host = cmd->device->host;
        struct pvscsi_adapter *adapter = shost_priv(host);
        unsigned long flags;

        scmd_printk(KERN_INFO, cmd, "SCSI device reset on scsi%u:%u\n",
                    host->host_no, cmd->device->id);

        /*
         * We don't want to queue new requests for this device after flushing
         * all pending requests to emulation, since new requests could then
         * sneak in during this device reset phase, so take the lock now.
         */
        spin_lock_irqsave(&adapter->hw_lock, flags);

        pvscsi_process_request_ring(adapter);
        ll_device_reset(adapter, cmd->device->id);
        pvscsi_process_completion_ring(adapter);

        spin_unlock_irqrestore(&adapter->hw_lock, flags);

        return SUCCESS;
}

static struct scsi_host_template pvscsi_template;

static const char *pvscsi_info(struct Scsi_Host *host)
{
        struct pvscsi_adapter *adapter = shost_priv(host);
        static char buf[256];

        sprintf(buf, "VMware PVSCSI storage adapter rev %d, req/cmp/msg rings: "
                "%u/%u/%u pages, cmd_per_lun=%u", adapter->rev,
                adapter->req_pages, adapter->cmp_pages, adapter->msg_pages,
                pvscsi_template.cmd_per_lun);

        return buf;
}

static struct scsi_host_template pvscsi_template = {
        .module                         = THIS_MODULE,
        .name                           = "VMware PVSCSI Host Adapter",
        .proc_name                      = "vmw_pvscsi",
        .info                           = pvscsi_info,
        .queuecommand                   = pvscsi_queue,
        .this_id                        = -1,
        .sg_tablesize                   = PVSCSI_MAX_NUM_SG_ENTRIES_PER_SEGMENT,
        .dma_boundary                   = UINT_MAX,
        .max_sectors                    = 0xffff,
        .change_queue_depth             = pvscsi_change_queue_depth,
        .eh_abort_handler               = pvscsi_abort,
        .eh_device_reset_handler        = pvscsi_device_reset,
        .eh_bus_reset_handler           = pvscsi_bus_reset,
        .eh_host_reset_handler          = pvscsi_host_reset,
};

static void pvscsi_process_msg(const struct pvscsi_adapter *adapter,
                               const struct PVSCSIRingMsgDesc *e)
{
        struct PVSCSIRingsState *s = adapter->rings_state;
        struct Scsi_Host *host = adapter->host;
        struct scsi_device *sdev;

        printk(KERN_INFO "vmw_pvscsi: msg type: 0x%x - MSG RING: %u/%u (%u) \n",
               e->type, s->msgProdIdx, s->msgConsIdx, s->msgNumEntriesLog2);

        BUILD_BUG_ON(PVSCSI_MSG_LAST != 2);

        if (e->type == PVSCSI_MSG_DEV_ADDED) {
                struct PVSCSIMsgDescDevStatusChanged *desc;
                desc = (struct PVSCSIMsgDescDevStatusChanged *)e;

                printk(KERN_INFO
                       "vmw_pvscsi: msg: device added at scsi%u:%u:%u\n",
                       desc->bus, desc->target, desc->lun[1]);

                if (!scsi_host_get(host))
                        return;

                sdev = scsi_device_lookup(host, desc->bus, desc->target,
                                          desc->lun[1]);
                if (sdev) {
                        printk(KERN_INFO "vmw_pvscsi: device already exists\n");
                        scsi_device_put(sdev);
                } else
                        scsi_add_device(adapter->host, desc->bus,
                                        desc->target, desc->lun[1]);

                scsi_host_put(host);
        } else if (e->type == PVSCSI_MSG_DEV_REMOVED) {
                struct PVSCSIMsgDescDevStatusChanged *desc;
                desc = (struct PVSCSIMsgDescDevStatusChanged *)e;

                printk(KERN_INFO
                       "vmw_pvscsi: msg: device removed at scsi%u:%u:%u\n",
                       desc->bus, desc->target, desc->lun[1]);

                if (!scsi_host_get(host))
                        return;

                sdev = scsi_device_lookup(host, desc->bus, desc->target,
                                          desc->lun[1]);
                if (sdev) {
                        scsi_remove_device(sdev);
                        scsi_device_put(sdev);
                } else
                        printk(KERN_INFO
                               "vmw_pvscsi: failed to lookup scsi%u:%u:%u\n",
                               desc->bus, desc->target, desc->lun[1]);

                scsi_host_put(host);
        }
}

static int pvscsi_msg_pending(const struct pvscsi_adapter *adapter)
{
        struct PVSCSIRingsState *s = adapter->rings_state;

        return s->msgProdIdx != s->msgConsIdx;
}

static void pvscsi_process_msg_ring(const struct pvscsi_adapter *adapter)
{
        struct PVSCSIRingsState *s = adapter->rings_state;
        struct PVSCSIRingMsgDesc *ring = adapter->msg_ring;
        u32 msg_entries = s->msgNumEntriesLog2;

        while (pvscsi_msg_pending(adapter)) {
                struct PVSCSIRingMsgDesc *e = ring + (s->msgConsIdx &
                                                      MASK(msg_entries));

                barrier();
                pvscsi_process_msg(adapter, e);
                barrier();
                s->msgConsIdx++;
        }
}

static void pvscsi_msg_workqueue_handler(struct work_struct *data)
{
        struct pvscsi_adapter *adapter;

        adapter = container_of(data, struct pvscsi_adapter, work);

        pvscsi_process_msg_ring(adapter);
}

static int pvscsi_setup_msg_workqueue(struct pvscsi_adapter *adapter)
{
        char name[32];

        if (!pvscsi_use_msg)
                return 0;

        pvscsi_reg_write(adapter, PVSCSI_REG_OFFSET_COMMAND,
                         PVSCSI_CMD_SETUP_MSG_RING);

        if (pvscsi_reg_read(adapter, PVSCSI_REG_OFFSET_COMMAND_STATUS) == -1)
                return 0;

        snprintf(name, sizeof(name),
                 "vmw_pvscsi_wq_%u", adapter->host->host_no);

        adapter->workqueue = create_singlethread_workqueue(name);
        if (!adapter->workqueue) {
                printk(KERN_ERR "vmw_pvscsi: failed to create work queue\n");
                return 0;
        }
        INIT_WORK(&adapter->work, pvscsi_msg_workqueue_handler);

        return 1;
}

static bool pvscsi_setup_req_threshold(struct pvscsi_adapter *adapter,
                                      bool enable)
{
        u32 val;

        if (!pvscsi_use_req_threshold)
                return false;

        pvscsi_reg_write(adapter, PVSCSI_REG_OFFSET_COMMAND,
                         PVSCSI_CMD_SETUP_REQCALLTHRESHOLD);
        val = pvscsi_reg_read(adapter, PVSCSI_REG_OFFSET_COMMAND_STATUS);
        if (val == -1) {
                printk(KERN_INFO "vmw_pvscsi: device does not support req_threshold\n");
                return false;
        } else {
                struct PVSCSICmdDescSetupReqCall cmd_msg = { 0 };
                cmd_msg.enable = enable;
                printk(KERN_INFO
                       "vmw_pvscsi: %sabling reqCallThreshold\n",
                        enable ? "en" : "dis");
                pvscsi_write_cmd_desc(adapter,
                                      PVSCSI_CMD_SETUP_REQCALLTHRESHOLD,
                                      &cmd_msg, sizeof(cmd_msg));
                return pvscsi_reg_read(adapter,
                                       PVSCSI_REG_OFFSET_COMMAND_STATUS) != 0;
        }
}

static irqreturn_t pvscsi_isr(int irq, void *devp)
{
        struct pvscsi_adapter *adapter = devp;
        unsigned long flags;

        spin_lock_irqsave(&adapter->hw_lock, flags);
        pvscsi_process_completion_ring(adapter);
        if (adapter->use_msg && pvscsi_msg_pending(adapter))
                queue_work(adapter->workqueue, &adapter->work);
        spin_unlock_irqrestore(&adapter->hw_lock, flags);

        return IRQ_HANDLED;
}

static irqreturn_t pvscsi_shared_isr(int irq, void *devp)
{
        struct pvscsi_adapter *adapter = devp;
        u32 val = pvscsi_read_intr_status(adapter);

        if (!(val & PVSCSI_INTR_ALL_SUPPORTED))
                return IRQ_NONE;
        pvscsi_write_intr_status(devp, val);
        return pvscsi_isr(irq, devp);
}

static void pvscsi_free_sgls(const struct pvscsi_adapter *adapter)
{
        struct pvscsi_ctx *ctx = adapter->cmd_map;
        unsigned i;

        for (i = 0; i < adapter->req_depth; ++i, ++ctx)
                free_pages((unsigned long)ctx->sgl, get_order(SGL_SIZE));
}

static void pvscsi_shutdown_intr(struct pvscsi_adapter *adapter)
{
        free_irq(pci_irq_vector(adapter->dev, 0), adapter);
        pci_free_irq_vectors(adapter->dev);
}

static void pvscsi_release_resources(struct pvscsi_adapter *adapter)
{
        if (adapter->workqueue)
                destroy_workqueue(adapter->workqueue);

        if (adapter->mmioBase)
                pci_iounmap(adapter->dev, adapter->mmioBase);

        pci_release_regions(adapter->dev);

        if (adapter->cmd_map) {
                pvscsi_free_sgls(adapter);
                kfree(adapter->cmd_map);
        }

        if (adapter->rings_state)
                dma_free_coherent(&adapter->dev->dev, PAGE_SIZE,
                                    adapter->rings_state, adapter->ringStatePA);

        if (adapter->req_ring)
                dma_free_coherent(&adapter->dev->dev,
                                    adapter->req_pages * PAGE_SIZE,
                                    adapter->req_ring, adapter->reqRingPA);

        if (adapter->cmp_ring)
                dma_free_coherent(&adapter->dev->dev,
                                    adapter->cmp_pages * PAGE_SIZE,
                                    adapter->cmp_ring, adapter->cmpRingPA);

        if (adapter->msg_ring)
                dma_free_coherent(&adapter->dev->dev,
                                    adapter->msg_pages * PAGE_SIZE,
                                    adapter->msg_ring, adapter->msgRingPA);
}

/*
 * Allocate scatter gather lists.
 *
 * These are statically allocated.  Trying to be clever was not worth it.
 *
 * Dynamic allocation can fail, and we can't go deep into the memory
 * allocator, since we're a SCSI driver, and trying too hard to allocate
 * memory might generate disk I/O.  We also don't want to fail disk I/O
 * in that case because we can't get an allocation - the I/O could be
 * trying to swap out data to free memory.  Since that is pathological,
 * just use a statically allocated scatter list.
 *
 */
static int pvscsi_allocate_sg(struct pvscsi_adapter *adapter)
{
        struct pvscsi_ctx *ctx;
        int i;

        ctx = adapter->cmd_map;
        BUILD_BUG_ON(sizeof(struct pvscsi_sg_list) > SGL_SIZE);

        for (i = 0; i < adapter->req_depth; ++i, ++ctx) {
                ctx->sgl = (void *)__get_free_pages(GFP_KERNEL,
                                                    get_order(SGL_SIZE));
                ctx->sglPA = 0;
                BUG_ON(!IS_ALIGNED(((unsigned long)ctx->sgl), PAGE_SIZE));
                if (!ctx->sgl) {
                        for (; i >= 0; --i, --ctx) {
                                free_pages((unsigned long)ctx->sgl,
                                           get_order(SGL_SIZE));
                                ctx->sgl = NULL;
                        }
                        return -ENOMEM;
                }
        }

        return 0;
}

/*
 * Query the device, fetch the config info and return the
 * maximum number of targets on the adapter. In case of
 * failure due to any reason return default i.e. 16.
 */
static u32 pvscsi_get_max_targets(struct pvscsi_adapter *adapter)
{
        struct PVSCSICmdDescConfigCmd cmd;
        struct PVSCSIConfigPageHeader *header;
        struct device *dev;
        dma_addr_t configPagePA;
        void *config_page;
        u32 numPhys = 16;

        dev = pvscsi_dev(adapter);
        config_page = dma_alloc_coherent(&adapter->dev->dev, PAGE_SIZE,
                        &configPagePA, GFP_KERNEL);
        if (!config_page) {
                dev_warn(dev, "vmw_pvscsi: failed to allocate memory for config page\n");
                goto exit;
        }
        BUG_ON(configPagePA & ~PAGE_MASK);

        /* Fetch config info from the device. */
        cmd.configPageAddress = ((u64)PVSCSI_CONFIG_CONTROLLER_ADDRESS) << 32;
        cmd.configPageNum = PVSCSI_CONFIG_PAGE_CONTROLLER;
        cmd.cmpAddr = configPagePA;
        cmd._pad = 0;

        /*
         * Mark the completion page header with error values. If the device
         * completes the command successfully, it sets the status values to
         * indicate success.
         */
        header = config_page;
        memset(header, 0, sizeof *header);
        header->hostStatus = BTSTAT_INVPARAM;
        header->scsiStatus = SDSTAT_CHECK;

        pvscsi_write_cmd_desc(adapter, PVSCSI_CMD_CONFIG, &cmd, sizeof cmd);

        if (header->hostStatus == BTSTAT_SUCCESS &&
            header->scsiStatus == SDSTAT_GOOD) {
                struct PVSCSIConfigPageController *config;

                config = config_page;
                numPhys = config->numPhys;
        } else
                dev_warn(dev, "vmw_pvscsi: PVSCSI_CMD_CONFIG failed. hostStatus = 0x%x, scsiStatus = 0x%x\n",
                         header->hostStatus, header->scsiStatus);
        dma_free_coherent(&adapter->dev->dev, PAGE_SIZE, config_page,
                          configPagePA);
exit:
        return numPhys;
}

static int pvscsi_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
        unsigned int irq_flag = PCI_IRQ_MSIX | PCI_IRQ_MSI | PCI_IRQ_LEGACY;
        struct pvscsi_adapter *adapter;
        struct pvscsi_adapter adapter_temp;
        struct Scsi_Host *host = NULL;
        unsigned int i;
        int error;
        u32 max_id;

        error = -ENODEV;

        if (pci_enable_device(pdev))
                return error;

        if (!dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64))) {
                printk(KERN_INFO "vmw_pvscsi: using 64bit dma\n");
        } else if (!dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32))) {
                printk(KERN_INFO "vmw_pvscsi: using 32bit dma\n");
        } else {
                printk(KERN_ERR "vmw_pvscsi: failed to set DMA mask\n");
                goto out_disable_device;
        }

        /*
         * Let's use a temp pvscsi_adapter struct until we find the number of
         * targets on the adapter, after that we will switch to the real
         * allocated struct.
         */
        adapter = &adapter_temp;
        memset(adapter, 0, sizeof(*adapter));
        adapter->dev  = pdev;
        adapter->rev = pdev->revision;

        if (pci_request_regions(pdev, "vmw_pvscsi")) {
                printk(KERN_ERR "vmw_pvscsi: pci memory selection failed\n");
                goto out_disable_device;
        }

        for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
                if ((pci_resource_flags(pdev, i) & PCI_BASE_ADDRESS_SPACE_IO))
                        continue;

                if (pci_resource_len(pdev, i) < PVSCSI_MEM_SPACE_SIZE)
                        continue;

                break;
        }

        if (i == DEVICE_COUNT_RESOURCE) {
                printk(KERN_ERR
                       "vmw_pvscsi: adapter has no suitable MMIO region\n");
                goto out_release_resources_and_disable;
        }

        adapter->mmioBase = pci_iomap(pdev, i, PVSCSI_MEM_SPACE_SIZE);

        if (!adapter->mmioBase) {
                printk(KERN_ERR
                       "vmw_pvscsi: can't iomap for BAR %d memsize %lu\n",
                       i, PVSCSI_MEM_SPACE_SIZE);
                goto out_release_resources_and_disable;
        }

        pci_set_master(pdev);

        /*
         * Ask the device for max number of targets before deciding the
         * default pvscsi_ring_pages value.
         */
        max_id = pvscsi_get_max_targets(adapter);
        printk(KERN_INFO "vmw_pvscsi: max_id: %u\n", max_id);

        if (pvscsi_ring_pages == 0)
                /*
                 * Set the right default value. Up to 16 it is 8, above it is
                 * max.
                 */
                pvscsi_ring_pages = (max_id > 16) ?
                        PVSCSI_SETUP_RINGS_MAX_NUM_PAGES :
                        PVSCSI_DEFAULT_NUM_PAGES_PER_RING;
        printk(KERN_INFO
               "vmw_pvscsi: setting ring_pages to %d\n",
               pvscsi_ring_pages);

        pvscsi_template.can_queue =
                min(PVSCSI_MAX_NUM_PAGES_REQ_RING, pvscsi_ring_pages) *
                PVSCSI_MAX_NUM_REQ_ENTRIES_PER_PAGE;
        pvscsi_template.cmd_per_lun =
                min(pvscsi_template.can_queue, pvscsi_cmd_per_lun);
        host = scsi_host_alloc(&pvscsi_template, sizeof(struct pvscsi_adapter));
        if (!host) {
                printk(KERN_ERR "vmw_pvscsi: failed to allocate host\n");
                goto out_release_resources_and_disable;
        }

        /*
         * Let's use the real pvscsi_adapter struct here onwards.
         */
        adapter = shost_priv(host);
        memset(adapter, 0, sizeof(*adapter));
        adapter->dev  = pdev;
        adapter->host = host;
        /*
         * Copy back what we already have to the allocated adapter struct.
         */
        adapter->rev = adapter_temp.rev;
        adapter->mmioBase = adapter_temp.mmioBase;

        spin_lock_init(&adapter->hw_lock);
        host->max_channel = 0;
        host->max_lun     = 1;
        host->max_cmd_len = 16;
        host->max_id      = max_id;

        pci_set_drvdata(pdev, host);

        ll_adapter_reset(adapter);

        adapter->use_msg = pvscsi_setup_msg_workqueue(adapter);

        error = pvscsi_allocate_rings(adapter);
        if (error) {
                printk(KERN_ERR "vmw_pvscsi: unable to allocate ring memory\n");
                goto out_release_resources;
        }

        /*
         * From this point on we should reset the adapter if anything goes
         * wrong.
         */
        pvscsi_setup_all_rings(adapter);

        adapter->cmd_map = kcalloc(adapter->req_depth,
                                   sizeof(struct pvscsi_ctx), GFP_KERNEL);
        if (!adapter->cmd_map) {
                printk(KERN_ERR "vmw_pvscsi: failed to allocate memory.\n");
                error = -ENOMEM;
                goto out_reset_adapter;
        }

        INIT_LIST_HEAD(&adapter->cmd_pool);
        for (i = 0; i < adapter->req_depth; i++) {
                struct pvscsi_ctx *ctx = adapter->cmd_map + i;
                list_add(&ctx->list, &adapter->cmd_pool);
        }

        error = pvscsi_allocate_sg(adapter);
        if (error) {
                printk(KERN_ERR "vmw_pvscsi: unable to allocate s/g table\n");
                goto out_reset_adapter;
        }

        if (pvscsi_disable_msix)
                irq_flag &= ~PCI_IRQ_MSIX;
        if (pvscsi_disable_msi)
                irq_flag &= ~PCI_IRQ_MSI;

        error = pci_alloc_irq_vectors(adapter->dev, 1, 1, irq_flag);
        if (error < 0)
                goto out_reset_adapter;

        adapter->use_req_threshold = pvscsi_setup_req_threshold(adapter, true);
        printk(KERN_DEBUG "vmw_pvscsi: driver-based request coalescing %sabled\n",
               adapter->use_req_threshold ? "en" : "dis");

        if (adapter->dev->msix_enabled || adapter->dev->msi_enabled) {
                printk(KERN_INFO "vmw_pvscsi: using MSI%s\n",
                        adapter->dev->msix_enabled ? "-X" : "");
                error = request_irq(pci_irq_vector(pdev, 0), pvscsi_isr,
                                0, "vmw_pvscsi", adapter);
        } else {
                printk(KERN_INFO "vmw_pvscsi: using INTx\n");
                error = request_irq(pci_irq_vector(pdev, 0), pvscsi_shared_isr,
                                IRQF_SHARED, "vmw_pvscsi", adapter);
        }

        if (error) {
                printk(KERN_ERR
                       "vmw_pvscsi: unable to request IRQ: %d\n", error);
                goto out_reset_adapter;
        }

        error = scsi_add_host(host, &pdev->dev);
        if (error) {
                printk(KERN_ERR
                       "vmw_pvscsi: scsi_add_host failed: %d\n", error);
                goto out_reset_adapter;
        }

        dev_info(&pdev->dev, "VMware PVSCSI rev %d host #%u\n",
                 adapter->rev, host->host_no);

        pvscsi_unmask_intr(adapter);

        scsi_scan_host(host);

        return 0;

out_reset_adapter:
        ll_adapter_reset(adapter);
out_release_resources:
        pvscsi_shutdown_intr(adapter);
        pvscsi_release_resources(adapter);
        scsi_host_put(host);
out_disable_device:
        pci_disable_device(pdev);

        return error;

out_release_resources_and_disable:
        pvscsi_shutdown_intr(adapter);
        pvscsi_release_resources(adapter);
        goto out_disable_device;
}

static void __pvscsi_shutdown(struct pvscsi_adapter *adapter)
{
        pvscsi_mask_intr(adapter);

        if (adapter->workqueue)
                flush_workqueue(adapter->workqueue);

        pvscsi_shutdown_intr(adapter);

        pvscsi_process_request_ring(adapter);
        pvscsi_process_completion_ring(adapter);
        ll_adapter_reset(adapter);
}

static void pvscsi_shutdown(struct pci_dev *dev)
{
        struct Scsi_Host *host = pci_get_drvdata(dev);
        struct pvscsi_adapter *adapter = shost_priv(host);

        __pvscsi_shutdown(adapter);
}

static void pvscsi_remove(struct pci_dev *pdev)
{
        struct Scsi_Host *host = pci_get_drvdata(pdev);
        struct pvscsi_adapter *adapter = shost_priv(host);

        scsi_remove_host(host);

        __pvscsi_shutdown(adapter);
        pvscsi_release_resources(adapter);

        scsi_host_put(host);

        pci_disable_device(pdev);
}

static struct pci_driver pvscsi_pci_driver = {
        .name           = "vmw_pvscsi",
        .id_table       = pvscsi_pci_tbl,
        .probe          = pvscsi_probe,
        .remove         = pvscsi_remove,
        .shutdown       = pvscsi_shutdown,
};

static int __init pvscsi_init(void)
{
        pr_info("%s - version %s\n",
                PVSCSI_LINUX_DRIVER_DESC, PVSCSI_DRIVER_VERSION_STRING);
        return pci_register_driver(&pvscsi_pci_driver);
}

static void __exit pvscsi_exit(void)
{
        pci_unregister_driver(&pvscsi_pci_driver);
}

module_init(pvscsi_init);
module_exit(pvscsi_exit);