text: /*
   * 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.
   *
   * Maintained by: Arvind Kumar <arvindkumar@vmware.com>
   *
   */
  
  #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;
  	unsigned int			irq;
  	u8				rev;
  	bool				use_msi;
  	bool				use_msix;
  	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++) {
  		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 void 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;
  
  	sg = scsi_sglist(cmd);
  	count = scsi_sg_count(cmd);
  	if (count != 0) {
  		int segs = scsi_dma_map(cmd);
  		if (segs > 1) {
  			pvscsi_create_sg(ctx, sg, segs);
  
  			e->flags |= PVSCSI_FLAG_CMD_WITH_SG_LIST;
  			ctx->sglPA = pci_map_single(adapter->dev, ctx->sgl,
  						    SGL_SIZE, PCI_DMA_TODEVICE);
  			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 = pci_map_single(adapter->dev, sg, bufflen,
  					     cmd->sc_data_direction);
  		e->dataAddr = ctx->dataPA;
  	}
  }
  
  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) {
  				pci_unmap_single(adapter->dev, ctx->sglPA,
  						 SGL_SIZE, PCI_DMA_TODEVICE);
  				ctx->sglPA = 0;
  			}
  		} else
  			pci_unmap_single(adapter->dev, ctx->dataPA, bufflen,
  					 cmd->sc_data_direction);
  	}
  	if (cmd->sense_buffer)
  		pci_unmap_single(adapter->dev, ctx->sensePA,
  				 SCSI_SENSE_BUFFERSIZE, PCI_DMA_FROMDEVICE);
  }
  
  static int pvscsi_allocate_rings(struct pvscsi_adapter *adapter)
  {
  	adapter->rings_state = pci_alloc_consistent(adapter->dev, PAGE_SIZE,
  						    &adapter->ringStatePA);
  	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 = pci_alloc_consistent(adapter->dev,
  						 adapter->req_pages * PAGE_SIZE,
  						 &adapter->reqRingPA);
  	if (!adapter->req_ring)
  		return -ENOMEM;
  
  	adapter->cmp_pages = min(PVSCSI_MAX_NUM_PAGES_CMP_RING,
  				 pvscsi_ring_pages);
  	adapter->cmp_ring = pci_alloc_consistent(adapter->dev,
  						 adapter->cmp_pages * PAGE_SIZE,
  						 &adapter->cmpRingPA);
  	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 = pci_alloc_consistent(adapter->dev,
  						 adapter->msg_pages * PAGE_SIZE,
  						 &adapter->msgRingPA);
  	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);
  	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)) {
  		cmd->result = (DID_OK << 16) | sdstat;
  		if (sdstat == SAM_STAT_CHECK_CONDITION && cmd->sense_buffer)
  			cmd->result |= (DRIVER_SENSE << 24);
  	} else
  		switch (btstat) {
  		case BTSTAT_SUCCESS:
  		case BTSTAT_LINKED_COMMAND_COMPLETED:
  		case BTSTAT_LINKED_COMMAND_COMPLETED_WITH_FLAG:
  			/* If everything went fine, let's move on..  */
  			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:
  			cmd->result = (DRIVER_INVALID << 24);
  			/* fall through */
  
  		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_ABORT << 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 = pci_map_single(adapter->dev, cmd->sense_buffer,
  					      SCSI_SENSE_BUFFERSIZE,
  					      PCI_DMA_FROMDEVICE);
  		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;
  
  	pvscsi_map_buffers(adapter, ctx, cmd, e);
  
  	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;
  
  	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;
  
  	dev_dbg(&cmd->device->sdev_gendev,
  		"queued cmd %p, ctx %p, op=%x\n", cmd, ctx, cmd->cmnd[0]);
  
  	spin_unlock_irqrestore(&adapter->hw_lock, flags);
  
  	pvscsi_kick_io(adapter, cmd->cmnd[0]);
  
  	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);
  
  	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. */
  	wait_for_completion_timeout(&abort_cmp, msecs_to_jiffies(2000));
  	spin_lock_irqsave(&adapter->hw_lock, flags);
  
  	if (!completion_done(&abort_cmp)) {
  		/*
  		 * 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_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 = 0;
  		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,
  	.use_clustering			= ENABLE_CLUSTERING,
  	.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;
  	int handled;
  
  	if (adapter->use_msi || adapter->use_msix)
  		handled = true;
  	else {
  		u32 val = pvscsi_read_intr_status(adapter);
  		handled = (val & PVSCSI_INTR_ALL_SUPPORTED) != 0;
  		if (handled)
  			pvscsi_write_intr_status(devp, val);
  	}
  
  	if (handled) {
  		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_RETVAL(handled);
  }
  
  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 int pvscsi_setup_msix(const struct pvscsi_adapter *adapter,
  			     unsigned int *irq)
  {
  	struct msix_entry entry = { 0, PVSCSI_VECTOR_COMPLETION };
  	int ret;
  
  	ret = pci_enable_msix_exact(adapter->dev, &entry, 1);
  	if (ret)
  		return ret;
  
  	*irq = entry.vector;
  
  	return 0;
  }
  
  static void pvscsi_shutdown_intr(struct pvscsi_adapter *adapter)
  {
  	if (adapter->irq) {
  		free_irq(adapter->irq, adapter);
  		adapter->irq = 0;
  	}
  	if (adapter->use_msi) {
  		pci_disable_msi(adapter->dev);
  		adapter->use_msi = 0;
  	} else if (adapter->use_msix) {
  		pci_disable_msix(adapter->dev);
  		adapter->use_msix = 0;
  	}
  }
  
  static void pvscsi_release_resources(struct pvscsi_adapter *adapter)
  {
  	pvscsi_shutdown_intr(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)
  		pci_free_consistent(adapter->dev, PAGE_SIZE,
  				    adapter->rings_state, adapter->ringStatePA);
  
  	if (adapter->req_ring)
  		pci_free_consistent(adapter->dev,
  				    adapter->req_pages * PAGE_SIZE,
  				    adapter->req_ring, adapter->reqRingPA);
  
  	if (adapter->cmp_ring)
  		pci_free_consistent(adapter->dev,
  				    adapter->cmp_pages * PAGE_SIZE,
  				    adapter->cmp_ring, adapter->cmpRingPA);
  
  	if (adapter->msg_ring)
  		pci_free_consistent(adapter->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 = pci_alloc_consistent(adapter->dev, PAGE_SIZE,
  					   &configPagePA);
  	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);
  	pci_free_consistent(adapter->dev, PAGE_SIZE, config_page, configPagePA);
  exit:
  	return numPhys;
  }
  
  static int pvscsi_probe(struct pci_dev *pdev, const struct pci_device_id *id)
  {
  	struct pvscsi_adapter *adapter;
  	struct pvscsi_adapter adapter_temp;
  	struct Scsi_Host *host = NULL;
  	unsigned int i;
  	unsigned long flags = 0;
  	int error;
  	u32 max_id;
  
  	error = -ENODEV;
  
  	if (pci_enable_device(pdev))
  		return error;
  
  	if (pci_set_dma_mask(pdev, DMA_BIT_MASK(64)) == 0 &&
  	    pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(64)) == 0) {
  		printk(KERN_INFO "vmw_pvscsi: using 64bit dma\n");
  	} else if (pci_set_dma_mask(pdev, DMA_BIT_MASK(32)) == 0 &&
  		   pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(32)) == 0) {
  		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 &&
  	    pvscsi_setup_msix(adapter, &adapter->irq) == 0) {
  		printk(KERN_INFO "vmw_pvscsi: using MSI-X\n");
  		adapter->use_msix = 1;
  	} else if (!pvscsi_disable_msi && pci_enable_msi(pdev) == 0) {
  		printk(KERN_INFO "vmw_pvscsi: using MSI\n");
  		adapter->use_msi = 1;
  		adapter->irq = pdev->irq;
  	} else {
  		printk(KERN_INFO "vmw_pvscsi: using INTx\n");
  		adapter->irq = pdev->irq;
  		flags = IRQF_SHARED;
  	}
  
  	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");
  
  	error = request_irq(adapter->irq, pvscsi_isr, flags,
  			    "vmw_pvscsi", adapter);
  	if (error) {
  		printk(KERN_ERR
  		       "vmw_pvscsi: unable to request IRQ: %d\n", error);
  		adapter->irq = 0;
  		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_release_resources(adapter);
  	scsi_host_put(host);
  out_disable_device:
  	pci_disable_device(pdev);
  
  	return error;
  
  out_release_resources_and_disable:
  	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);
  