drm - Fix major stalls by fixing an improper taskqueue priority

[dragonfly.git] / sys / dev / raid / mrsas / mrsas_cam.c

/*
 * Copyright (c) 2014, LSI Corp.
 * All rights reserved.
 * Author: Marian Choy
 * Support: freebsdraid@lsi.com
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name of the <ORGANIZATION> nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * $FreeBSD: head/sys/dev/mrsas/mrsas_cam.c 265555 2014-05-07 16:16:49Z ambrisko $
 */

#include <dev/raid/mrsas/mrsas.h>

#include <bus/cam/cam.h>
#include <bus/cam/cam_ccb.h>
#include <bus/cam/cam_sim.h>
#include <bus/cam/cam_xpt_sim.h>
#include <bus/cam/cam_debug.h>
#include <bus/cam/cam_periph.h>
#include <bus/cam/cam_xpt_periph.h>

#include <bus/cam/scsi/scsi_all.h>
#include <bus/cam/scsi/scsi_message.h>
#include <sys/taskqueue.h>


/*
 * Function prototypes
 */
int mrsas_cam_attach(struct mrsas_softc *sc);
//int mrsas_ldio_inq(union ccb *ccb); 
int mrsas_ldio_inq(struct cam_sim *sim, union ccb *ccb); 
int mrsas_bus_scan(struct mrsas_softc *sc);
int mrsas_bus_scan_sim(struct mrsas_softc *sc, struct cam_sim *sim);
int mrsas_map_request(struct mrsas_softc *sc, struct mrsas_mpt_cmd *cmd);
int mrsas_build_ldio(struct mrsas_softc *sc, struct mrsas_mpt_cmd *cmd,
                    union ccb *ccb);
int mrsas_build_dcdb(struct mrsas_softc *sc, struct mrsas_mpt_cmd *cmd,
                    union ccb *ccb, struct cam_sim *sim);
int mrsas_setup_io(struct mrsas_softc *sc, struct mrsas_mpt_cmd *cmd,
                    union ccb *ccb, u_int32_t device_id,
                    MRSAS_RAID_SCSI_IO_REQUEST *io_request);
void mrsas_xpt_freeze(struct mrsas_softc *sc);
void mrsas_xpt_release(struct mrsas_softc *sc);
void mrsas_cam_detach(struct mrsas_softc *sc);
void mrsas_release_mpt_cmd(struct mrsas_mpt_cmd *cmd); 
void mrsas_unmap_request(struct mrsas_softc *sc, struct mrsas_mpt_cmd *cmd);
void mrsas_cmd_done(struct mrsas_softc *sc, struct mrsas_mpt_cmd *cmd);
void mrsas_fire_cmd(struct mrsas_softc *sc, u_int32_t req_desc_lo,
                    u_int32_t req_desc_hi);
void mrsas_set_pd_lba(MRSAS_RAID_SCSI_IO_REQUEST *io_request, u_int8_t cdb_len, 
                    struct IO_REQUEST_INFO *io_info, union ccb *ccb, 
                    MR_FW_RAID_MAP_ALL *local_map_ptr, u_int32_t ref_tag,
                    u_int32_t ld_block_size);
static void mrsas_freeze_simq(struct mrsas_mpt_cmd *cmd, struct cam_sim *sim);
static void mrsas_poll(struct cam_sim *sim);
static void mrsas_action(struct cam_sim *sim, union ccb *ccb);
static void mrsas_scsiio_timeout(void *data);
static void mrsas_data_load_cb(void *arg, bus_dma_segment_t *segs,
                    int nseg, int error);
static int32_t mrsas_startio(struct mrsas_softc *sc, struct cam_sim *sim, 
                    union ccb *ccb);
static void mrsas_rescan_callback(struct cam_periph *, union ccb *);
struct mrsas_mpt_cmd * mrsas_get_mpt_cmd(struct mrsas_softc *sc); 
MRSAS_REQUEST_DESCRIPTOR_UNION *mrsas_get_request_desc(struct mrsas_softc *sc, 
                    u_int16_t index);

extern u_int16_t MR_TargetIdToLdGet(u_int32_t ldTgtId, MR_FW_RAID_MAP_ALL *map);
extern u_int32_t MR_LdBlockSizeGet(u_int32_t ldTgtId, MR_FW_RAID_MAP_ALL *map,
    struct mrsas_softc *sc);
extern void mrsas_isr(void *arg);
extern void mrsas_aen_handler(struct mrsas_softc *sc);
extern u_int8_t MR_BuildRaidContext(struct mrsas_softc *sc, 
        struct IO_REQUEST_INFO *io_info,RAID_CONTEXT *pRAID_Context, 
        MR_FW_RAID_MAP_ALL *map);
extern u_int16_t MR_LdSpanArrayGet(u_int32_t ld, u_int32_t span, 
        MR_FW_RAID_MAP_ALL *map); 
extern u_int16_t mrsas_get_updated_dev_handle(PLD_LOAD_BALANCE_INFO lbInfo,
        struct IO_REQUEST_INFO *io_info);
extern u_int8_t megasas_get_best_arm(PLD_LOAD_BALANCE_INFO lbInfo, u_int8_t arm,
       u_int64_t block, u_int32_t count);


/**
 * mrsas_cam_attach:        Main entry to CAM subsystem 
 * input:                   Adapter instance soft state 
 *
 * This function is called from mrsas_attach() during initialization
 * to perform SIM allocations and XPT bus registration.  If the kernel 
 * version is 7.4 or earlier, it would also initiate a bus scan.
 */
int mrsas_cam_attach(struct mrsas_softc *sc)
{
    struct cam_devq *devq;
    int mrsas_cam_depth;

    mrsas_cam_depth = sc->max_fw_cmds - MRSAS_INTERNAL_CMDS;
    
    if ((devq = cam_simq_alloc(mrsas_cam_depth)) == NULL) {
        device_printf(sc->mrsas_dev, "Cannot allocate SIM queue\n");
        return(ENOMEM);
    }


    /* 
     * Create SIM for bus 0 and register, also create path 
     */
    sc->sim_0 = cam_sim_alloc(mrsas_action, mrsas_poll, "mrsas", sc,
        device_get_unit(sc->mrsas_dev), &sc->sim_lock, mrsas_cam_depth,
        mrsas_cam_depth, devq);
    if (sc->sim_0 == NULL){
        device_printf(sc->mrsas_dev, "Cannot register SIM\n");
        cam_simq_release(devq);
        return(ENXIO);
    }
    /* Initialize taskqueue for Event Handling */
    TASK_INIT(&sc->ev_task, 0, (void *)mrsas_aen_handler, sc);
    sc->ev_tq = taskqueue_create("mrsas_taskq", M_NOWAIT | M_ZERO,
        taskqueue_thread_enqueue, &sc->ev_tq);

    /* Run the task queue with lowest priority */
    taskqueue_start_threads(&sc->ev_tq, 1, TDPRI_KERN_DAEMON,
                            -1, "%s taskq",
        device_get_nameunit(sc->mrsas_dev));
    lockmgr(&sc->sim_lock, LK_EXCLUSIVE);
    if (xpt_bus_register(sc->sim_0, 0) != CAM_SUCCESS)
    {
        cam_sim_free(sc->sim_0);
        cam_simq_release(devq);
        lockmgr(&sc->sim_lock, LK_RELEASE); 
        return(ENXIO);
    }
    if (xpt_create_path(&sc->path_0, NULL, cam_sim_path(sc->sim_0),
                         CAM_TARGET_WILDCARD,
                         CAM_LUN_WILDCARD) != CAM_REQ_CMP) {
        xpt_bus_deregister(cam_sim_path(sc->sim_0));
        cam_sim_free(sc->sim_0);
        cam_simq_release(devq);
        lockmgr(&sc->sim_lock, LK_RELEASE); 
        return(ENXIO);
    }
    lockmgr(&sc->sim_lock, LK_RELEASE);

    /* 
     * Create SIM for bus 1 and register, also create path 
     */
    sc->sim_1 = cam_sim_alloc(mrsas_action, mrsas_poll, "mrsas", sc,
        device_get_unit(sc->mrsas_dev), &sc->sim_lock, mrsas_cam_depth,
        mrsas_cam_depth, devq);
    cam_simq_release(devq);
    if (sc->sim_1 == NULL){
        device_printf(sc->mrsas_dev, "Cannot register SIM\n");
        return(ENXIO);
    }

    lockmgr(&sc->sim_lock, LK_EXCLUSIVE);
    if (xpt_bus_register(sc->sim_1, 1) != CAM_SUCCESS){
        cam_sim_free(sc->sim_1);
        lockmgr(&sc->sim_lock, LK_RELEASE);
        return(ENXIO);
    }
    if (xpt_create_path(&sc->path_1, NULL, cam_sim_path(sc->sim_1),
                         CAM_TARGET_WILDCARD,
                         CAM_LUN_WILDCARD) != CAM_REQ_CMP) {
        xpt_bus_deregister(cam_sim_path(sc->sim_1));
        cam_sim_free(sc->sim_1);
        lockmgr(&sc->sim_lock, LK_RELEASE);
        return(ENXIO);
    }
    lockmgr(&sc->sim_lock, LK_RELEASE);

    if (mrsas_bus_scan(sc)){
        device_printf(sc->mrsas_dev, "Error in bus scan.\n");
        return(1);
    }
    return(0);
}

/**
 * mrsas_cam_detach:        De-allocates and teardown CAM  
 * input:                   Adapter instance soft state 
 *
 * De-registers and frees the paths and SIMs. 
 */
void mrsas_cam_detach(struct mrsas_softc *sc)
{
    if (sc->ev_tq != NULL)
        taskqueue_free(sc->ev_tq);
    lockmgr(&sc->sim_lock, LK_EXCLUSIVE);
    if (sc->path_0)
        xpt_free_path(sc->path_0);
    if (sc->sim_0) {
        xpt_bus_deregister(cam_sim_path(sc->sim_0));
        cam_sim_free(sc->sim_0);
    }
    if (sc->path_1)
        xpt_free_path(sc->path_1);
    if (sc->sim_1) {
        xpt_bus_deregister(cam_sim_path(sc->sim_1));
        cam_sim_free(sc->sim_1);
    }
    lockmgr(&sc->sim_lock, LK_RELEASE);
}

/**
 * mrsas_action:            SIM callback entry point   
 * input:                   pointer to SIM 
 *                          pointer to CAM Control Block
 *
 * This function processes CAM subsystem requests. The type of request is
 * stored in ccb->ccb_h.func_code.  The preprocessor #ifdef is necessary
 * because ccb->cpi.maxio is not supported for FreeBSD version 7.4 or 
 * earlier.   
 */
static void mrsas_action(struct cam_sim *sim, union ccb *ccb)
{
    struct mrsas_softc *sc = (struct mrsas_softc *)cam_sim_softc(sim);
    struct ccb_hdr *ccb_h = &(ccb->ccb_h);
    u_int32_t device_id;

    switch (ccb->ccb_h.func_code) {
        case XPT_SCSI_IO:
        {
            device_id = ccb_h->target_id;

            /* 
             * bus 0 is LD, bus 1 is for system-PD 
             */ 
            if (cam_sim_bus(sim) == 1 && 
                sc->pd_list[device_id].driveState != MR_PD_STATE_SYSTEM) {
                ccb->ccb_h.status |= CAM_DEV_NOT_THERE;
                xpt_done(ccb);
            }
            else {
                if (mrsas_startio(sc, sim, ccb)){
                    ccb->ccb_h.status |= CAM_REQ_INVALID;
                    xpt_done(ccb);
                }
            }
            break;
        }
        case XPT_ABORT:
        {
            ccb->ccb_h.status = CAM_UA_ABORT;
            xpt_done(ccb);
            break;
        }
        case XPT_RESET_BUS:
        {
            xpt_done(ccb);
            break;
        }
        case XPT_GET_TRAN_SETTINGS:
        {
            ccb->cts.protocol = PROTO_SCSI;
            ccb->cts.protocol_version = SCSI_REV_2;
            ccb->cts.transport = XPORT_SPI;
            ccb->cts.transport_version = 2;  
            ccb->cts.xport_specific.spi.valid = CTS_SPI_VALID_DISC;
            ccb->cts.xport_specific.spi.flags = CTS_SPI_FLAGS_DISC_ENB;
            ccb->cts.proto_specific.scsi.valid = CTS_SCSI_VALID_TQ;
            ccb->cts.proto_specific.scsi.flags = CTS_SCSI_FLAGS_TAG_ENB;
            ccb->ccb_h.status = CAM_REQ_CMP;
            xpt_done(ccb);
            break;
        }
        case XPT_SET_TRAN_SETTINGS:
        {
            ccb->ccb_h.status = CAM_FUNC_NOTAVAIL; 
            xpt_done(ccb);
            break;
        }
        case XPT_CALC_GEOMETRY:
        {
            cam_calc_geometry(&ccb->ccg, 1);   
            xpt_done(ccb);
            break;
        }
        case XPT_PATH_INQ:
        {
            ccb->cpi.version_num = 1;
            ccb->cpi.hba_inquiry = 0;
            ccb->cpi.target_sprt = 0;
            ccb->cpi.hba_misc = 0;
            ccb->cpi.hba_eng_cnt = 0;
            ccb->cpi.max_lun = MRSAS_SCSI_MAX_LUNS;
            ccb->cpi.unit_number = cam_sim_unit(sim);
            ccb->cpi.bus_id = cam_sim_bus(sim);
            ccb->cpi.initiator_id = MRSAS_SCSI_INITIATOR_ID; 
            ccb->cpi.base_transfer_speed = 150000; 
            strncpy(ccb->cpi.sim_vid, "FreeBSD", SIM_IDLEN);
            strncpy(ccb->cpi.hba_vid, "LSI", HBA_IDLEN);
            strncpy(ccb->cpi.dev_name, cam_sim_name(sim), DEV_IDLEN);
            ccb->cpi.transport = XPORT_SPI;
            ccb->cpi.transport_version = 2;
            ccb->cpi.protocol = PROTO_SCSI;
            ccb->cpi.protocol_version = SCSI_REV_2;
            if (ccb->cpi.bus_id == 0)
                ccb->cpi.max_target = MRSAS_MAX_LD-1;
            else
                ccb->cpi.max_target = MRSAS_MAX_PD-1;
            ccb->cpi.maxio = MRSAS_MAX_IO_SIZE;
            ccb->ccb_h.status = CAM_REQ_CMP;
            xpt_done(ccb);
            break;
        }
        default:
        {
            ccb->ccb_h.status = CAM_REQ_INVALID;
            xpt_done(ccb);
            break;
        }
    }
}

/**
 * mrsas_scsiio_timeout         Callback function for IO timed out
 * input:                       mpt command context
 *
 * This function will execute after timeout value
 * provided by ccb header from CAM layer, if timer expires.
 * Driver will run timer for all DCDM and LDIO comming from CAM layer.
 * This function is callback function for IO timeout and it runs in
 * no-sleep context. Set do_timedout_reset in Adapter context so that
 * it will execute OCR/Kill adpter from ocr_thread context.
 */
static void
mrsas_scsiio_timeout(void *data)
{
    struct mrsas_mpt_cmd *cmd;
    struct mrsas_softc *sc;

    cmd = (struct mrsas_mpt_cmd *)data;
    sc = cmd->sc;

    if (cmd->ccb_ptr == NULL) {
        kprintf("command timeout with NULL ccb\n");
        return;
    }

    /* Below callout is dummy entry so that it will be
     * cancelled from mrsas_cmd_done(). Now Controller will
     * go to OCR/Kill Adapter based on OCR enable/disable
     * property of Controller from ocr_thread context.
     */
    callout_reset(&cmd->cm_callout, (600000 * hz) / 1000,
    mrsas_scsiio_timeout, cmd);
    sc->do_timedout_reset = 1;
    if(sc->ocr_thread_active)
        wakeup(&sc->ocr_chan);
}

/**
 * mrsas_startio:           SCSI IO entry point   
 * input:                   Adapter instance soft state 
 *                          pointer to CAM Control Block
 *
 * This function is the SCSI IO entry point and it initiates IO processing. 
 * It copies the IO and depending if the IO is read/write or inquiry, it would 
 * call mrsas_build_ldio() or mrsas_build_dcdb(), respectively.  It returns
 * 0 if the command is sent to firmware successfully, otherwise it returns 1.
 */
static int32_t mrsas_startio(struct mrsas_softc *sc, struct cam_sim *sim, 
                             union ccb *ccb)
{
    struct mrsas_mpt_cmd *cmd;
    struct ccb_hdr *ccb_h = &(ccb->ccb_h);
    struct ccb_scsiio *csio = &(ccb->csio);
    MRSAS_REQUEST_DESCRIPTOR_UNION *req_desc;

    if ((csio->cdb_io.cdb_bytes[0]) == SYNCHRONIZE_CACHE){
        ccb->ccb_h.status = CAM_REQ_CMP;
        xpt_done(ccb);
        return(0);
    }

    ccb_h->status |= CAM_SIM_QUEUED;
    cmd = mrsas_get_mpt_cmd(sc);

    if (!cmd) {
        ccb_h->status |= CAM_REQUEUE_REQ;
        xpt_done(ccb);
        return(0);  
    }

    if ((ccb_h->flags & CAM_DIR_MASK) != CAM_DIR_NONE) {
        if(ccb_h->flags & CAM_DIR_IN)
            cmd->flags |= MRSAS_DIR_IN;
        if(ccb_h->flags & CAM_DIR_OUT)
            cmd->flags |= MRSAS_DIR_OUT;
    } 
    else 
        cmd->flags = MRSAS_DIR_NONE; /* no data */

/* For FreeBSD 10.0 and higher */
#if 0 /* XXX (__FreeBSD_version >= 1000000) */
/*
 *      * XXX We don't yet support physical addresses here.
 */ 
    switch ((ccb->ccb_h.flags & CAM_DATA_MASK)) {
    case CAM_DATA_PADDR:
    case CAM_DATA_SG_PADDR:
         kprintf("%s: physical addresses not supported\n",
               __func__);
         mrsas_release_mpt_cmd(cmd);
         ccb_h->status = CAM_REQ_INVALID;
         ccb_h->status &= ~CAM_SIM_QUEUED;
         goto done;
    case CAM_DATA_SG:
         kprintf("%s: scatter gather is not supported\n",
               __func__);
         mrsas_release_mpt_cmd(cmd);
         ccb_h->status = CAM_REQ_INVALID;
         goto done;
        case CAM_DATA_VADDR:
         if (csio->dxfer_len > MRSAS_MAX_IO_SIZE) {
              mrsas_release_mpt_cmd(cmd);
              ccb_h->status = CAM_REQ_TOO_BIG;
              goto done;
          }
          cmd->length = csio->dxfer_len;
          if (cmd->length) 
              cmd->data = csio->data_ptr;
        break;
    default:
        ccb->ccb_h.status = CAM_REQ_INVALID;
        goto done;
    }
#else
    if (!(ccb_h->flags & CAM_DATA_PHYS)) {  //Virtual data address
         if (!(ccb_h->flags & CAM_SCATTER_VALID)) {
             if (csio->dxfer_len > MRSAS_MAX_IO_SIZE) {
                 mrsas_release_mpt_cmd(cmd);
                 ccb_h->status = CAM_REQ_TOO_BIG;
                 goto done;
             }
             cmd->length = csio->dxfer_len;
             if (cmd->length) 
                 cmd->data = csio->data_ptr;
         } 
         else { 
             mrsas_release_mpt_cmd(cmd);
             ccb_h->status = CAM_REQ_INVALID;
             goto done;
         }
    } 
    else { //Data addresses are physical.
         mrsas_release_mpt_cmd(cmd);
         ccb_h->status = CAM_REQ_INVALID;
         ccb_h->status &= ~CAM_SIM_QUEUED;
         goto done;
    }
#endif
    /* save ccb ptr */
    cmd->ccb_ptr = ccb;

    req_desc = mrsas_get_request_desc(sc, (cmd->index)-1);
    if (!req_desc) {
        device_printf(sc->mrsas_dev, "Cannot get request_descriptor.\n");
        return (FAIL);
    }
    memset(req_desc, 0, sizeof(MRSAS_REQUEST_DESCRIPTOR_UNION));
    cmd->request_desc = req_desc;

    if (ccb_h->flags & CAM_CDB_POINTER)
        bcopy(csio->cdb_io.cdb_ptr, cmd->io_request->CDB.CDB32, csio->cdb_len);
    else
        bcopy(csio->cdb_io.cdb_bytes, cmd->io_request->CDB.CDB32, csio->cdb_len);
    lockmgr(&sc->raidmap_lock, LK_EXCLUSIVE);

    if (mrsas_ldio_inq(sim, ccb)) {
        if (mrsas_build_ldio(sc, cmd, ccb)){
            device_printf(sc->mrsas_dev, "Build LDIO failed.\n");
            lockmgr(&sc->raidmap_lock, LK_RELEASE);
            return(1);
        }    
    }
    else { 
        if (mrsas_build_dcdb(sc, cmd, ccb, sim)) {
            device_printf(sc->mrsas_dev, "Build DCDB failed.\n");
            lockmgr(&sc->raidmap_lock, LK_RELEASE);
            return(1);
        }
    }
    lockmgr(&sc->raidmap_lock, LK_RELEASE);

    if (cmd->flags == MRSAS_DIR_IN) //from device
        cmd->io_request->Control |= MPI2_SCSIIO_CONTROL_READ;
    else if (cmd->flags == MRSAS_DIR_OUT)  //to device
        cmd->io_request->Control |= MPI2_SCSIIO_CONTROL_WRITE;

    cmd->io_request->SGLFlags = MPI2_SGE_FLAGS_64_BIT_ADDRESSING;
    cmd->io_request->SGLOffset0 = offsetof(MRSAS_RAID_SCSI_IO_REQUEST, SGL)/4;
    cmd->io_request->SenseBufferLowAddress = cmd->sense_phys_addr;
    cmd->io_request->SenseBufferLength = MRSAS_SCSI_SENSE_BUFFERSIZE;

    req_desc = cmd->request_desc;
    req_desc->SCSIIO.SMID = cmd->index;

    /*
     * Start timer for IO timeout. Default timeout value is 90 second.
     */
    callout_reset(&cmd->cm_callout, (sc->mrsas_io_timeout * hz) / 1000,
        mrsas_scsiio_timeout, cmd);
    atomic_inc(&sc->fw_outstanding);

        if(atomic_read(&sc->fw_outstanding) > sc->io_cmds_highwater)
        sc->io_cmds_highwater++;

    mrsas_fire_cmd(sc, req_desc->addr.u.low, req_desc->addr.u.high);
    return(0);

done:
    xpt_done(ccb);
    return(0);
}

/**
 * mrsas_ldio_inq:           Determines if IO is read/write or inquiry   
 * input:                        pointer to CAM Control Block
 *
 * This function determines if the IO is read/write or inquiry.  It returns a
 * 1 if the IO is read/write and 0 if it is inquiry.
 */
int mrsas_ldio_inq(struct cam_sim *sim, union ccb *ccb) 
{
    struct ccb_scsiio *csio = &(ccb->csio);

    if (cam_sim_bus(sim) == 1)
        return(0);

    switch (csio->cdb_io.cdb_bytes[0]) {
        case READ_10:
        case WRITE_10:
        case READ_12:
        case WRITE_12:
        case READ_6:
        case WRITE_6:
        case READ_16:
        case WRITE_16:
            return 1;
        default:
            return 0;
    }
}

/**
 * mrsas_get_mpt_cmd:            Get a cmd from free command pool  
 * input:                        Adapter instance soft state 
 *
 * This function removes an MPT command from the command free list and 
 * initializes it.
 */
struct mrsas_mpt_cmd* mrsas_get_mpt_cmd(struct mrsas_softc *sc) 
{
    struct mrsas_mpt_cmd *cmd = NULL;

    lockmgr(&sc->mpt_cmd_pool_lock, LK_EXCLUSIVE);
    if (!TAILQ_EMPTY(&sc->mrsas_mpt_cmd_list_head)){
        cmd = TAILQ_FIRST(&sc->mrsas_mpt_cmd_list_head);
        TAILQ_REMOVE(&sc->mrsas_mpt_cmd_list_head, cmd, next);
    }
    memset((uint8_t *)cmd->io_request, 0, MRSAS_MPI2_RAID_DEFAULT_IO_FRAME_SIZE);
    cmd->data = NULL;
    cmd->length = 0;
    cmd->flags = 0;
    cmd->error_code = 0;
    cmd->load_balance = 0;
    cmd->ccb_ptr = NULL;
    lockmgr(&sc->mpt_cmd_pool_lock, LK_RELEASE);

    return cmd;
}

/**
 * mrsas_release_mpt_cmd:      Return a cmd to free command pool  
 * input:                      Command packet for return to free command pool 
 *
 * This function returns an MPT command to the free command list.
 */
void mrsas_release_mpt_cmd(struct mrsas_mpt_cmd *cmd) 
{
    struct mrsas_softc *sc = cmd->sc;

    lockmgr(&sc->mpt_cmd_pool_lock, LK_EXCLUSIVE);
    cmd->sync_cmd_idx = (u_int32_t)MRSAS_ULONG_MAX;
    TAILQ_INSERT_TAIL(&(sc->mrsas_mpt_cmd_list_head), cmd, next);
    lockmgr(&sc->mpt_cmd_pool_lock, LK_RELEASE);

    return; 
}

/**
 * mrsas_get_request_desc:     Get request descriptor from array  
 * input:                      Adapter instance soft state
 *                             SMID index 
 *
 * This function returns a pointer to the request descriptor.
 */
MRSAS_REQUEST_DESCRIPTOR_UNION *
mrsas_get_request_desc(struct mrsas_softc *sc, u_int16_t index)
{
    u_int8_t *p;

    if (index >= sc->max_fw_cmds) {
        device_printf(sc->mrsas_dev, "Invalid SMID (0x%x)request for desc\n", index);
        return NULL;
    }
    p = sc->req_desc + sizeof(MRSAS_REQUEST_DESCRIPTOR_UNION) * index;

    return (MRSAS_REQUEST_DESCRIPTOR_UNION *)p;
}

/**
 * mrsas_build_ldio:       Builds an LDIO command  
 * input:                  Adapter instance soft state
 *                         Pointer to command packet
 *                         Pointer to CCB 
 *
 * This function builds the LDIO command packet.  It returns 0 if the 
 * command is built successfully, otherwise it returns a 1. 
 */
int mrsas_build_ldio(struct mrsas_softc *sc, struct mrsas_mpt_cmd *cmd,
                      union ccb *ccb)
{
    struct ccb_hdr *ccb_h = &(ccb->ccb_h);
    struct ccb_scsiio *csio = &(ccb->csio);
    u_int32_t device_id;
    MRSAS_RAID_SCSI_IO_REQUEST *io_request;

    device_id = ccb_h->target_id;

    io_request = cmd->io_request;
    io_request->RaidContext.VirtualDiskTgtId = device_id;
    io_request->RaidContext.status = 0;
    io_request->RaidContext.exStatus = 0;

    /* just the cdb len, other flags zero, and ORed-in later for FP */ 
    io_request->IoFlags = csio->cdb_len;

    if (mrsas_setup_io(sc, cmd, ccb, device_id, io_request) != SUCCESS)
        device_printf(sc->mrsas_dev, "Build ldio or fpio error\n"); 
        
    io_request->DataLength = cmd->length;

    if (mrsas_map_request(sc, cmd) == SUCCESS) {
        if (cmd->sge_count > MRSAS_MAX_SGL) {
            device_printf(sc->mrsas_dev, "Error: sge_count (0x%x) exceeds" 
                "max (0x%x) allowed\n", cmd->sge_count, sc->max_num_sge);
            return (FAIL);
        }
        io_request->RaidContext.numSGE = cmd->sge_count;
    }
    else {
        device_printf(sc->mrsas_dev, "Data map/load failed.\n");
        return(FAIL);
    } 
    return(0);
}

/**
 * mrsas_setup_io:             Set up data including Fast Path I/O  
 * input:                      Adapter instance soft state
 *                             Pointer to command packet
 *                             Pointer to CCB 
 *
 * This function builds the DCDB inquiry command.  It returns 0 if the 
 * command is built successfully, otherwise it returns a 1. 
 */
int mrsas_setup_io(struct mrsas_softc *sc, struct mrsas_mpt_cmd *cmd,
                    union ccb *ccb, u_int32_t device_id,
                    MRSAS_RAID_SCSI_IO_REQUEST *io_request)
{
    struct ccb_hdr *ccb_h = &(ccb->ccb_h);
    struct ccb_scsiio *csio = &(ccb->csio);
    struct IO_REQUEST_INFO io_info;
    MR_FW_RAID_MAP_ALL *map_ptr;
    u_int8_t fp_possible;
    u_int32_t start_lba_hi, start_lba_lo, ld_block_size;
    u_int32_t datalength = 0;
     
    start_lba_lo = 0;
    start_lba_hi = 0;
    fp_possible = 0;
     
    /*
     * READ_6 (0x08) or WRITE_6 (0x0A) cdb
     */
    if (csio->cdb_len == 6) {
        datalength = (u_int32_t)csio->cdb_io.cdb_bytes[4];
        start_lba_lo = ((u_int32_t) csio->cdb_io.cdb_bytes[1] << 16) |
                       ((u_int32_t) csio->cdb_io.cdb_bytes[2] << 8) |
                        (u_int32_t) csio->cdb_io.cdb_bytes[3];
        start_lba_lo &= 0x1FFFFF;
    }
    /*
     * READ_10 (0x28) or WRITE_6 (0x2A) cdb
     */
    else if (csio->cdb_len == 10) {
        datalength = (u_int32_t)csio->cdb_io.cdb_bytes[8] |
                       ((u_int32_t)csio->cdb_io.cdb_bytes[7] << 8);
        start_lba_lo = ((u_int32_t) csio->cdb_io.cdb_bytes[2] << 24) |
                       ((u_int32_t) csio->cdb_io.cdb_bytes[3] << 16) |
                        (u_int32_t) csio->cdb_io.cdb_bytes[4] << 8 |
                        ((u_int32_t) csio->cdb_io.cdb_bytes[5]);
    }
    /*
     * READ_12 (0xA8) or WRITE_12 (0xAA) cdb
     */
    else if (csio->cdb_len == 12) {
        datalength = (u_int32_t)csio->cdb_io.cdb_bytes[6] << 24 |
                       ((u_int32_t)csio->cdb_io.cdb_bytes[7] << 16) |
                       ((u_int32_t)csio->cdb_io.cdb_bytes[8] << 8) |
                       ((u_int32_t)csio->cdb_io.cdb_bytes[9]);
        start_lba_lo = ((u_int32_t) csio->cdb_io.cdb_bytes[2] << 24) |
                       ((u_int32_t) csio->cdb_io.cdb_bytes[3] << 16) |
                        (u_int32_t) csio->cdb_io.cdb_bytes[4] << 8 |
                        ((u_int32_t) csio->cdb_io.cdb_bytes[5]);
    }
    /*
     * READ_16 (0x88) or WRITE_16 (0xx8A) cdb
     */
    else if (csio->cdb_len == 16) {
        datalength = (u_int32_t)csio->cdb_io.cdb_bytes[10] << 24 |
                       ((u_int32_t)csio->cdb_io.cdb_bytes[11] << 16) |
                       ((u_int32_t)csio->cdb_io.cdb_bytes[12] << 8) |
                       ((u_int32_t)csio->cdb_io.cdb_bytes[13]);
        start_lba_lo = ((u_int32_t) csio->cdb_io.cdb_bytes[6] << 24) |
                       ((u_int32_t) csio->cdb_io.cdb_bytes[7] << 16) |
                        (u_int32_t) csio->cdb_io.cdb_bytes[8] << 8 |
                        ((u_int32_t) csio->cdb_io.cdb_bytes[9]);
        start_lba_hi = ((u_int32_t) csio->cdb_io.cdb_bytes[2] << 24) |
                       ((u_int32_t) csio->cdb_io.cdb_bytes[3] << 16) |
                        (u_int32_t) csio->cdb_io.cdb_bytes[4] << 8 |
                        ((u_int32_t) csio->cdb_io.cdb_bytes[5]);
    }

    memset(&io_info, 0, sizeof(struct IO_REQUEST_INFO));
    io_info.ldStartBlock = ((u_int64_t)start_lba_hi << 32) | start_lba_lo;
    io_info.numBlocks = datalength;
    io_info.ldTgtId = device_id;

    switch (ccb_h->flags & CAM_DIR_MASK) {
        case CAM_DIR_IN:
                io_info.isRead = 1;
                break;
        case CAM_DIR_OUT:
                io_info.isRead = 0;
                break;
        case CAM_DIR_NONE:
        default:
        mrsas_dprint(sc, MRSAS_TRACE, "From %s : DMA Flag is %d \n", __func__, ccb_h->flags & CAM_DIR_MASK);
                break;
    }

    map_ptr = sc->raidmap_mem[(sc->map_id & 1)];
    ld_block_size = MR_LdBlockSizeGet(device_id, map_ptr, sc);

    if ((MR_TargetIdToLdGet(device_id, map_ptr) >= MAX_LOGICAL_DRIVES) || 
            (!sc->fast_path_io)) {
        io_request->RaidContext.regLockFlags = 0;
        fp_possible = 0;
    } 
    else 
    {
        if (MR_BuildRaidContext(sc, &io_info, &io_request->RaidContext, map_ptr))
            fp_possible = io_info.fpOkForIo;
    }

    if (fp_possible) {
        mrsas_set_pd_lba(io_request, csio->cdb_len, &io_info, ccb, map_ptr, 
            start_lba_lo, ld_block_size);
        io_request->Function = MPI2_FUNCTION_SCSI_IO_REQUEST;
        cmd->request_desc->SCSIIO.RequestFlags =
                        (MPI2_REQ_DESCRIPT_FLAGS_HIGH_PRIORITY
                         << MRSAS_REQ_DESCRIPT_FLAGS_TYPE_SHIFT);
            if ((sc->device_id == MRSAS_INVADER) || (sc->device_id == MRSAS_FURY)) {
                    if (io_request->RaidContext.regLockFlags == REGION_TYPE_UNUSED)
                cmd->request_desc->SCSIIO.RequestFlags = (MRSAS_REQ_DESCRIPT_FLAGS_NO_LOCK << MRSAS_REQ_DESCRIPT_FLAGS_TYPE_SHIFT);
            io_request->RaidContext.Type = MPI2_TYPE_CUDA;
            io_request->RaidContext.nseg = 0x1;
            io_request->IoFlags |= MPI25_SAS_DEVICE0_FLAGS_ENABLED_FAST_PATH;
            io_request->RaidContext.regLockFlags |= (MR_RL_FLAGS_GRANT_DESTINATION_CUDA | MR_RL_FLAGS_SEQ_NUM_ENABLE);
        }
        if ((sc->load_balance_info[device_id].loadBalanceFlag) && (io_info.isRead)) {
            io_info.devHandle = mrsas_get_updated_dev_handle(&sc->load_balance_info[device_id], 
                &io_info);
            cmd->load_balance = MRSAS_LOAD_BALANCE_FLAG;
        } 
        else
            cmd->load_balance = 0;
        cmd->request_desc->SCSIIO.DevHandle = io_info.devHandle;
        io_request->DevHandle = io_info.devHandle;
    } 
    else {
        /* Not FP IO */
        io_request->RaidContext.timeoutValue = map_ptr->raidMap.fpPdIoTimeoutSec;
        cmd->request_desc->SCSIIO.RequestFlags =
            (MRSAS_REQ_DESCRIPT_FLAGS_LD_IO << MRSAS_REQ_DESCRIPT_FLAGS_TYPE_SHIFT);
            if ((sc->device_id == MRSAS_INVADER) || (sc->device_id == MRSAS_FURY)) {
            if (io_request->RaidContext.regLockFlags == REGION_TYPE_UNUSED)
                cmd->request_desc->SCSIIO.RequestFlags = (MRSAS_REQ_DESCRIPT_FLAGS_NO_LOCK << MRSAS_REQ_DESCRIPT_FLAGS_TYPE_SHIFT);
            io_request->RaidContext.Type = MPI2_TYPE_CUDA;
            io_request->RaidContext.regLockFlags |= (MR_RL_FLAGS_GRANT_DESTINATION_CPU0 | MR_RL_FLAGS_SEQ_NUM_ENABLE);
            io_request->RaidContext.nseg = 0x1;
        }
        io_request->Function = MRSAS_MPI2_FUNCTION_LD_IO_REQUEST;
        io_request->DevHandle = device_id;
    }
    return(0);
}

/**
 * mrsas_build_dcdb:       Builds an DCDB command  
 * input:                  Adapter instance soft state
 *                         Pointer to command packet
 *                         Pointer to CCB 
 *
 * This function builds the DCDB inquiry command.  It returns 0 if the 
 * command is built successfully, otherwise it returns a 1. 
 */
int mrsas_build_dcdb(struct mrsas_softc *sc, struct mrsas_mpt_cmd *cmd,
                      union ccb *ccb, struct cam_sim *sim)
{
    struct ccb_hdr *ccb_h = &(ccb->ccb_h);
    u_int32_t device_id;
    MR_FW_RAID_MAP_ALL *map_ptr;
    MRSAS_RAID_SCSI_IO_REQUEST *io_request;

    io_request = cmd->io_request;
    device_id = ccb_h->target_id;
    map_ptr = sc->raidmap_mem[(sc->map_id & 1)];

    /* Check if this is for system PD */ 
    if (cam_sim_bus(sim) == 1 && 
            sc->pd_list[device_id].driveState == MR_PD_STATE_SYSTEM) {
        io_request->Function = 0;
        io_request->DevHandle = map_ptr->raidMap.devHndlInfo[device_id].curDevHdl;
        io_request->RaidContext.timeoutValue = map_ptr->raidMap.fpPdIoTimeoutSec;
        io_request->RaidContext.regLockFlags = 0;
        io_request->RaidContext.regLockRowLBA = 0;
        io_request->RaidContext.regLockLength = 0;
        io_request->RaidContext.RAIDFlags = MR_RAID_FLAGS_IO_SUB_TYPE_SYSTEM_PD << 
            MR_RAID_CTX_RAID_FLAGS_IO_SUB_TYPE_SHIFT;
            if ((sc->device_id == MRSAS_INVADER) || (sc->device_id == MRSAS_FURY))
            io_request->IoFlags |= MPI25_SAS_DEVICE0_FLAGS_ENABLED_FAST_PATH;
        cmd->request_desc->SCSIIO.RequestFlags = 
            (MPI2_REQ_DESCRIPT_FLAGS_HIGH_PRIORITY << 
            MRSAS_REQ_DESCRIPT_FLAGS_TYPE_SHIFT);
        cmd->request_desc->SCSIIO.DevHandle = 
            map_ptr->raidMap.devHndlInfo[device_id].curDevHdl;
    }
    else {
        io_request->Function  = MRSAS_MPI2_FUNCTION_LD_IO_REQUEST;
        io_request->DevHandle = device_id;
        cmd->request_desc->SCSIIO.RequestFlags =
            (MPI2_REQ_DESCRIPT_FLAGS_SCSI_IO << MRSAS_REQ_DESCRIPT_FLAGS_TYPE_SHIFT);
    }
        
    io_request->RaidContext.VirtualDiskTgtId = device_id;
    io_request->LUN[1] = ccb_h->target_lun & 0xF;
    io_request->DataLength = cmd->length;

    if (mrsas_map_request(sc, cmd) == SUCCESS) {
        if (cmd->sge_count > sc->max_num_sge) {
            device_printf(sc->mrsas_dev, "Error: sge_count (0x%x) exceeds" 
                "max (0x%x) allowed\n", cmd->sge_count, sc->max_num_sge);
            return (1);
        }
        io_request->RaidContext.numSGE = cmd->sge_count;
    }
    else {
        device_printf(sc->mrsas_dev, "Data map/load failed.\n");
        return(1);
    } 
    return(0);
}

/**
 * mrsas_map_request:           Map and load data   
 * input:                       Adapter instance soft state
 *                              Pointer to command packet
 *
 * For data from OS, map and load the data buffer into bus space.  The
 * SG list is built in the callback.  If the  bus dmamap load is not
 * successful, cmd->error_code will contain the  error code and a 1 is 
 * returned.
 */
int mrsas_map_request(struct mrsas_softc *sc, struct mrsas_mpt_cmd *cmd)
{
    u_int32_t retcode = 0;
    struct cam_sim *sim;
    int flag = BUS_DMA_NOWAIT;

    sim = xpt_path_sim(cmd->ccb_ptr->ccb_h.path);

    if (cmd->data != NULL) {
        lockmgr(&sc->io_lock, LK_EXCLUSIVE);
        /* Map data buffer into bus space */
        retcode = bus_dmamap_load(sc->data_tag, cmd->data_dmamap, cmd->data,
                              cmd->length, mrsas_data_load_cb, cmd, flag);
        lockmgr(&sc->io_lock, LK_RELEASE);
        if (retcode)
            device_printf(sc->mrsas_dev, "bus_dmamap_load(): retcode = %d\n", retcode);
        if (retcode == EINPROGRESS) {
            device_printf(sc->mrsas_dev, "request load in progress\n");
            mrsas_freeze_simq(cmd, sim);
        } 
    }
    if (cmd->error_code)
        return(1);
    return(retcode);
}

/**
 * mrsas_unmap_request:       Unmap and unload data   
 * input:                     Adapter instance soft state
 *                            Pointer to command packet
 *
 * This function unmaps and unloads data from OS.
 */
void mrsas_unmap_request(struct mrsas_softc *sc, struct mrsas_mpt_cmd *cmd)
{
    if (cmd->data != NULL) {
        if (cmd->flags & MRSAS_DIR_IN)
            bus_dmamap_sync(sc->data_tag, cmd->data_dmamap, BUS_DMASYNC_POSTREAD);
        if (cmd->flags & MRSAS_DIR_OUT)
            bus_dmamap_sync(sc->data_tag, cmd->data_dmamap, BUS_DMASYNC_POSTWRITE);
        lockmgr(&sc->io_lock, LK_EXCLUSIVE);
        bus_dmamap_unload(sc->data_tag, cmd->data_dmamap);
        lockmgr(&sc->io_lock, LK_RELEASE);
    }
}

/**
 * mrsas_data_load_cb:        Callback entry point   
 * input:                     Pointer to command packet as argument 
 *                            Pointer to segment
 *                            Number of segments
 *                            Error 
 *
 * This is the callback function of the bus dma map load.  It builds 
 * the SG list.  
 */
static void
mrsas_data_load_cb(void *arg, bus_dma_segment_t *segs, int nseg, int error)
{
    struct mrsas_mpt_cmd *cmd = (struct mrsas_mpt_cmd *)arg;
    struct mrsas_softc *sc = cmd->sc;
    MRSAS_RAID_SCSI_IO_REQUEST *io_request;
    pMpi25IeeeSgeChain64_t sgl_ptr;
    int i=0, sg_processed=0;

    if (error)
    {
        cmd->error_code = error;
        device_printf(sc->mrsas_dev, "mrsas_data_load_cb: error=%d\n", error);
        if (error == EFBIG) {
            cmd->ccb_ptr->ccb_h.status = CAM_REQ_TOO_BIG;
            return;
        }
    }

    if (cmd->flags & MRSAS_DIR_IN)
        bus_dmamap_sync(cmd->sc->data_tag, cmd->data_dmamap,
                                            BUS_DMASYNC_PREREAD);
    if (cmd->flags & MRSAS_DIR_OUT)
        bus_dmamap_sync(cmd->sc->data_tag, cmd->data_dmamap,
                                            BUS_DMASYNC_PREWRITE);
    if (nseg > sc->max_num_sge) {
        device_printf(sc->mrsas_dev, "SGE count is too large or 0.\n");
        return;
    }

    io_request = cmd->io_request;
    sgl_ptr = (pMpi25IeeeSgeChain64_t)&io_request->SGL;

    if ((sc->device_id == MRSAS_INVADER) || (sc->device_id == MRSAS_FURY)) {
        pMpi25IeeeSgeChain64_t sgl_ptr_end = sgl_ptr;
        sgl_ptr_end += sc->max_sge_in_main_msg - 1;
        sgl_ptr_end->Flags = 0;
    }

    if (nseg != 0) {
        for (i=0; i < nseg; i++) {
            sgl_ptr->Address = segs[i].ds_addr;
            sgl_ptr->Length = segs[i].ds_len;
            sgl_ptr->Flags = 0;
                if ((sc->device_id == MRSAS_INVADER) || (sc->device_id == MRSAS_FURY)) {
                if (i == nseg - 1)
                        sgl_ptr->Flags = IEEE_SGE_FLAGS_END_OF_LIST;
            }
                sgl_ptr++;
                sg_processed = i + 1;
                /* 
             * Prepare chain element 
             */
                        if ((sg_processed == (sc->max_sge_in_main_msg - 1)) &&
                                (nseg > sc->max_sge_in_main_msg)) {
                                        pMpi25IeeeSgeChain64_t sg_chain;
                                        if ((sc->device_id == MRSAS_INVADER) || (sc->device_id == MRSAS_FURY)) {
                                                if ((cmd->io_request->IoFlags & MPI25_SAS_DEVICE0_FLAGS_ENABLED_FAST_PATH)
                                                                                                        != MPI25_SAS_DEVICE0_FLAGS_ENABLED_FAST_PATH)
                                                         cmd->io_request->ChainOffset = sc->chain_offset_io_request;
                                           else
                                                           cmd->io_request->ChainOffset = 0;
                                        } else
                                                         cmd->io_request->ChainOffset = sc->chain_offset_io_request;
                                        sg_chain = sgl_ptr;
                                        if ((sc->device_id == MRSAS_INVADER) || (sc->device_id == MRSAS_FURY))
                                                 sg_chain->Flags = IEEE_SGE_FLAGS_CHAIN_ELEMENT;
                                    else
                                                 sg_chain->Flags = (IEEE_SGE_FLAGS_CHAIN_ELEMENT | MPI2_IEEE_SGE_FLAGS_IOCPLBNTA_ADDR);
                                        sg_chain->Length = (sizeof(MPI2_SGE_IO_UNION) * (nseg - sg_processed));
                                        sg_chain->Address = cmd->chain_frame_phys_addr;
                                        sgl_ptr = (pMpi25IeeeSgeChain64_t)cmd->chain_frame;
                        }
        }
    }
    cmd->sge_count = nseg;
}

/**
 * mrsas_freeze_simq:        Freeze SIM queue   
 * input:                    Pointer to command packet  
 *                           Pointer to SIM
 *
 * This function freezes the sim queue.
 */
static void mrsas_freeze_simq(struct mrsas_mpt_cmd *cmd, struct cam_sim *sim)
{
    union ccb   *ccb = (union ccb *)(cmd->ccb_ptr);

    xpt_freeze_simq(sim, 1);
    ccb->ccb_h.status |= CAM_RELEASE_SIMQ;
    ccb->ccb_h.status |= CAM_REQUEUE_REQ;
}

void mrsas_xpt_freeze(struct mrsas_softc *sc) {
    xpt_freeze_simq(sc->sim_0, 1);
    xpt_freeze_simq(sc->sim_1, 1);
}
            
void mrsas_xpt_release(struct mrsas_softc *sc) {
    xpt_release_simq(sc->sim_0, 1);
    xpt_release_simq(sc->sim_1, 1);
}

/**
 * mrsas_cmd_done:           Perform remaining command completion 
 * input:                    Adapter instance soft state  
 *                           Pointer to command packet 
 *
 * This function calls ummap request and releases the MPT command. 
 */
void mrsas_cmd_done(struct mrsas_softc *sc, struct mrsas_mpt_cmd *cmd)
{
    callout_stop(&cmd->cm_callout);
    mrsas_unmap_request(sc, cmd);
    lockmgr(&sc->sim_lock, LK_EXCLUSIVE);
    xpt_done(cmd->ccb_ptr);
    cmd->ccb_ptr = NULL;
    lockmgr(&sc->sim_lock, LK_RELEASE);
    mrsas_release_mpt_cmd(cmd);
}

/**
 * mrsas_poll:               Polling entry point 
 * input:                    Pointer to SIM  
 *
 * This is currently a stub function.
 */
static void mrsas_poll(struct cam_sim *sim)
{
    struct mrsas_softc *sc = (struct mrsas_softc *)cam_sim_softc(sim);
    mrsas_isr((void *) sc);
}

static void
mrsas_rescan_callback(struct cam_periph *periph, union ccb *ccb)
{
        xpt_free_path(ccb->ccb_h.path);
        xpt_free_ccb(ccb);
}

/*
 * mrsas_bus_scan:           Perform bus scan 
 * input:                    Adapter instance soft state  
 *
 * This mrsas_bus_scan function is needed for FreeBSD 7.x.  Also, it should
 * not be called in FreeBSD 8.x and later versions, where the bus scan is 
 * automatic. 
 */ 
int mrsas_bus_scan(struct mrsas_softc *sc)
{
    union ccb *ccb_0;
    union ccb *ccb_1;

    lockmgr(&sc->sim_lock, LK_EXCLUSIVE);
    if ((ccb_0 = xpt_alloc_ccb()) == NULL) {
        lockmgr(&sc->sim_lock, LK_RELEASE);
        return(ENOMEM);
    }

    if ((ccb_1 = xpt_alloc_ccb()) == NULL) {
        xpt_free_ccb(ccb_0);
        lockmgr(&sc->sim_lock, LK_RELEASE);
        return(ENOMEM);
    } 

    if (xpt_create_path(&ccb_0->ccb_h.path, xpt_periph, cam_sim_path(sc->sim_0),
            CAM_TARGET_WILDCARD, CAM_LUN_WILDCARD) != CAM_REQ_CMP){
        xpt_free_ccb(ccb_0);
        xpt_free_ccb(ccb_1);
        lockmgr(&sc->sim_lock, LK_RELEASE);
        return(EIO);
    }

    if (xpt_create_path(&ccb_1->ccb_h.path, xpt_periph, cam_sim_path(sc->sim_1),
            CAM_TARGET_WILDCARD, CAM_LUN_WILDCARD) != CAM_REQ_CMP){
        xpt_free_ccb(ccb_0);
        xpt_free_ccb(ccb_1);
        lockmgr(&sc->sim_lock, LK_RELEASE);
        return(EIO);
    }

    xpt_setup_ccb(&ccb_0->ccb_h, ccb_0->ccb_h.path, 5/*priority (low)*/);
    ccb_0->ccb_h.func_code = XPT_SCAN_BUS;
    ccb_0->ccb_h.cbfcnp = mrsas_rescan_callback;
    ccb_0->crcn.flags = CAM_FLAG_NONE;
    xpt_action(ccb_0); /* scan is now in progress */

    xpt_setup_ccb(&ccb_1->ccb_h, ccb_1->ccb_h.path, 5/*priority (low)*/);
    ccb_1->ccb_h.func_code = XPT_SCAN_BUS;
    ccb_1->ccb_h.cbfcnp = mrsas_rescan_callback;
    ccb_1->crcn.flags = CAM_FLAG_NONE;
    xpt_action(ccb_1); /* scan is now in progress */

    lockmgr(&sc->sim_lock, LK_RELEASE);

    return(0);
}

/*
 * mrsas_bus_scan_sim:          Perform bus scan per SIM
 * input:                                       Adapter instance soft state  
 *                                                      This function will be called from Event handler 
 *                                                      on LD creation/deletion, JBOD on/off.
 */ 
int mrsas_bus_scan_sim(struct mrsas_softc *sc, struct cam_sim *sim)
{
    union ccb *ccb;

    lockmgr(&sc->sim_lock, LK_EXCLUSIVE);
    if ((ccb = xpt_alloc_ccb()) == NULL) {
        lockmgr(&sc->sim_lock, LK_RELEASE);
        return(ENOMEM);
    }
    if (xpt_create_path(&ccb->ccb_h.path, xpt_periph, cam_sim_path(sim),
            CAM_TARGET_WILDCARD, CAM_LUN_WILDCARD) != CAM_REQ_CMP){
        xpt_free_ccb(ccb);
        lockmgr(&sc->sim_lock, LK_RELEASE);
        return(EIO);
    }
    xpt_setup_ccb(&ccb->ccb_h, ccb->ccb_h.path, 5/*priority (low)*/);
    ccb->ccb_h.func_code = XPT_SCAN_BUS;
    ccb->ccb_h.cbfcnp = mrsas_rescan_callback;
    ccb->crcn.flags = CAM_FLAG_NONE;
    xpt_action(ccb); /* scan is now in progress */

    lockmgr(&sc->sim_lock, LK_RELEASE);

    return(0);
}