/*-
 * Copyright (c) 2009 Yahoo! Inc.
 * All rights reserved.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 *
 */
/*-
 * Copyright (c) 2011 LSI Corp.
 * All rights reserved.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 *
 * LSI MPT-Fusion Host Adapter FreeBSD
 *
 * $FreeBSD: src/sys/dev/mps/mps.c,v 1.14 2012/01/26 18:17:21 ken Exp $
 */

/* Communications core for LSI MPT2 */

/* TODO Move headers to mpsvar */
#include <sys/types.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/globaldata.h>
#include <sys/module.h>
#include <sys/bus.h>
#include <sys/conf.h>
#include <sys/bio.h>
#include <sys/malloc.h>
#include <sys/uio.h>
#include <sys/sysctl.h>
#include <sys/queue.h>
#include <sys/kthread.h>
#include <sys/endian.h>
#include <sys/eventhandler.h>

#include <sys/rman.h>

#include <bus/pci/pcivar.h>

#include <bus/cam/scsi/scsi_all.h>

#include <dev/raid/mps/mpi/mpi2_type.h>
#include <dev/raid/mps/mpi/mpi2.h>
#include <dev/raid/mps/mpi/mpi2_ioc.h>
#include <dev/raid/mps/mpi/mpi2_sas.h>
#include <dev/raid/mps/mpi/mpi2_cnfg.h>
#include <dev/raid/mps/mpi/mpi2_init.h>
#include <dev/raid/mps/mpi/mpi2_tool.h>
#include <dev/raid/mps/mps_ioctl.h>
#include <dev/raid/mps/mpsvar.h>
#include <dev/raid/mps/mps_table.h>

static int mps_diag_reset(struct mps_softc *sc);
static int mps_init_queues(struct mps_softc *sc);
static int mps_message_unit_reset(struct mps_softc *sc);
static int mps_transition_operational(struct mps_softc *sc);
static void mps_startup(void *arg);
static int mps_send_iocinit(struct mps_softc *sc);
static int mps_attach_log(struct mps_softc *sc);
static __inline void mps_complete_command(struct mps_command *cm);
static void mps_dispatch_event(struct mps_softc *sc, uintptr_t data,
    MPI2_EVENT_NOTIFICATION_REPLY *reply);
static void mps_config_complete(struct mps_softc *sc, struct mps_command *cm);
static void mps_periodic(void *);
static int mps_reregister_events(struct mps_softc *sc);
static void mps_enqueue_request(struct mps_softc *sc, struct mps_command *cm);

SYSCTL_NODE(_hw, OID_AUTO, mps, CTLFLAG_RD, 0, "MPS Driver Parameters");

MALLOC_DEFINE(M_MPT2, "mps", "mpt2 driver memory");

/*
 * Do a "Diagnostic Reset" aka a hard reset.  This should get the chip out of
 * any state and back to its initialization state machine.
 */
static char mpt2_reset_magic[] = { 0x00, 0x0f, 0x04, 0x0b, 0x02, 0x07, 0x0d };

static int
mps_diag_reset(struct mps_softc *sc)
{
        uint32_t reg;
        int i, error, tries = 0;

        mps_dprint(sc, MPS_TRACE, "%s\n", __func__);

        /* Clear any pending interrupts */
        mps_regwrite(sc, MPI2_HOST_INTERRUPT_STATUS_OFFSET, 0x0);

        /* Push the magic sequence */
        error = ETIMEDOUT;
        while (tries++ < 20) {
                for (i = 0; i < sizeof(mpt2_reset_magic); i++)
                        mps_regwrite(sc, MPI2_WRITE_SEQUENCE_OFFSET,
                            mpt2_reset_magic[i]);

                DELAY(100 * 1000);

                reg = mps_regread(sc, MPI2_HOST_DIAGNOSTIC_OFFSET);
                if (reg & MPI2_DIAG_DIAG_WRITE_ENABLE) {
                        error = 0;
                        break;
                }
        }
        if (error)
                return (error);

        /* Send the actual reset.  XXX need to refresh the reg? */
        mps_regwrite(sc, MPI2_HOST_DIAGNOSTIC_OFFSET,
            reg | MPI2_DIAG_RESET_ADAPTER);

        /* Wait up to 300 seconds in 50ms intervals */
        error = ETIMEDOUT;
        for (i = 0; i < 60000; i++) {
                DELAY(50000);
                reg = mps_regread(sc, MPI2_DOORBELL_OFFSET);
                if ((reg & MPI2_IOC_STATE_MASK) != MPI2_IOC_STATE_RESET) {
                        error = 0;
                        break;
                }
        }
        if (error)
                return (error);

        mps_regwrite(sc, MPI2_WRITE_SEQUENCE_OFFSET, 0x0);

        return (0);
}

static int
mps_message_unit_reset(struct mps_softc *sc)
{

        mps_dprint(sc, MPS_TRACE, "%s\n", __func__);

        mps_regwrite(sc, MPI2_DOORBELL_OFFSET,
            MPI2_FUNCTION_IOC_MESSAGE_UNIT_RESET <<
            MPI2_DOORBELL_FUNCTION_SHIFT);
        DELAY(50000);

        return (0);
}

static int
mps_transition_ready(struct mps_softc *sc)
{
        uint32_t reg, state;
        int error, tries = 0;

        mps_dprint(sc, MPS_TRACE, "%s\n", __func__);

        error = 0;
        while (tries++ < 5) {
                reg = mps_regread(sc, MPI2_DOORBELL_OFFSET);
                mps_dprint(sc, MPS_INFO, "Doorbell= 0x%x\n", reg);

                /*
                 * Ensure the IOC is ready to talk.  If it's not, try
                 * resetting it.
                 */
                if (reg & MPI2_DOORBELL_USED) {
                        mps_diag_reset(sc);
                        DELAY(50000);
                        continue;
                }

                /* Is the adapter owned by another peer? */
                if ((reg & MPI2_DOORBELL_WHO_INIT_MASK) ==
                    (MPI2_WHOINIT_PCI_PEER << MPI2_DOORBELL_WHO_INIT_SHIFT)) {
                        device_printf(sc->mps_dev, "IOC is under the control "
                            "of another peer host, aborting initialization.\n");
                        return (ENXIO);
                }

                state = reg & MPI2_IOC_STATE_MASK;
                if (state == MPI2_IOC_STATE_READY) {
                        /* Ready to go! */
                        error = 0;
                        break;
                } else if (state == MPI2_IOC_STATE_FAULT) {
                        mps_dprint(sc, MPS_INFO, "IOC in fault state 0x%x\n",
                            state & MPI2_DOORBELL_FAULT_CODE_MASK);
                        mps_diag_reset(sc);
                } else if (state == MPI2_IOC_STATE_OPERATIONAL) {
                        /* Need to take ownership */
                        mps_message_unit_reset(sc);
                } else if (state == MPI2_IOC_STATE_RESET) {
                        /* Wait a bit, IOC might be in transition */
                        mps_dprint(sc, MPS_FAULT,
                            "IOC in unexpected reset state\n");
                } else {
                        mps_dprint(sc, MPS_FAULT,
                            "IOC in unknown state 0x%x\n", state);
                        error = EINVAL;
                        break;
                }

                /* Wait 50ms for things to settle down. */
                DELAY(50000);
        }

        if (error)
                device_printf(sc->mps_dev, "Cannot transition IOC to ready\n");

        return (error);
}

static int
mps_transition_operational(struct mps_softc *sc)
{
        uint32_t reg, state;
        int error;

        mps_dprint(sc, MPS_TRACE, "%s\n", __func__);

        error = 0;
        reg = mps_regread(sc, MPI2_DOORBELL_OFFSET);
        mps_dprint(sc, MPS_INFO, "Doorbell= 0x%x\n", reg);

        state = reg & MPI2_IOC_STATE_MASK;
        if (state != MPI2_IOC_STATE_READY) {
                if ((error = mps_transition_ready(sc)) != 0) {
                        mps_dprint(sc, MPS_FAULT,
                            "%s failed to transition ready\n", __func__);
                        return (error);
                }
        }

        error = mps_send_iocinit(sc);
        return (error);
}

/*
 * XXX Some of this should probably move to mps.c
 *
 * The terms diag reset and hard reset are used interchangeably in the MPI
 * docs to mean resetting the controller chip.  In this code diag reset
 * cleans everything up, and the hard reset function just sends the reset
 * sequence to the chip.  This should probably be refactored so that every
 * subsystem gets a reset notification of some sort, and can clean up
 * appropriately.
 */
int
mps_reinit(struct mps_softc *sc)
{
        int error;
        uint32_t db;

        mps_printf(sc, "%s sc %p\n", __func__, sc);

        KKASSERT(lockowned(&sc->mps_lock));

        if (sc->mps_flags & MPS_FLAGS_DIAGRESET) {
                mps_printf(sc, "%s reset already in progress\n", __func__);
                return 0;
        }

        /* make sure the completion callbacks can recognize they're getting
         * a NULL cm_reply due to a reset.
         */
        sc->mps_flags |= MPS_FLAGS_DIAGRESET;

        mps_printf(sc, "%s mask interrupts\n", __func__);
        mps_mask_intr(sc);

        error = mps_diag_reset(sc);
        if (error != 0) {
                panic("%s hard reset failed with error %d",
                    __func__, error);
        }

        /* Restore the PCI state, including the MSI-X registers */
        mps_pci_restore(sc);

        /* Give the I/O subsystem special priority to get itself prepared */
        mpssas_handle_reinit(sc);

        /* reinitialize queues after the reset */
        bzero(sc->free_queue, sc->fqdepth * 4);
        mps_init_queues(sc);

        /* get the chip out of the reset state */
        error = mps_transition_operational(sc);
        if (error != 0)
                panic("%s transition operational failed with error %d",
                    __func__, error);

        /* Reinitialize the reply queue. This is delicate because this
         * function is typically invoked by task mgmt completion callbacks,
         * which are called by the interrupt thread.  We need to make sure
         * the interrupt handler loop will exit when we return to it, and
         * that it will recognize the indexes we've changed.
         */
        sc->replypostindex = 0;
        mps_regwrite(sc, MPI2_REPLY_FREE_HOST_INDEX_OFFSET, sc->replyfreeindex);
        mps_regwrite(sc, MPI2_REPLY_POST_HOST_INDEX_OFFSET, sc->replypostindex);

        db = mps_regread(sc, MPI2_DOORBELL_OFFSET);
        mps_printf(sc, "%s doorbell 0x%08x\n", __func__, db);

        mps_printf(sc, "%s unmask interrupts post %u free %u\n", __func__,
            sc->replypostindex, sc->replyfreeindex);

        mps_unmask_intr(sc);

        mps_printf(sc, "%s restarting post %u free %u\n", __func__,
            sc->replypostindex, sc->replyfreeindex);

        /* restart will reload the event masks clobbered by the reset, and
         * then enable the port.
         */
        mps_reregister_events(sc);

        /* the end of discovery will release the simq, so we're done. */
        mps_printf(sc, "%s finished sc %p post %u free %u\n",
            __func__, sc,
            sc->replypostindex, sc->replyfreeindex);

        sc->mps_flags &= ~MPS_FLAGS_DIAGRESET;

        return 0;
}

/* Wait for the chip to ACK a word that we've put into its FIFO */
static int
mps_wait_db_ack(struct mps_softc *sc)
{
        int retry;

        for (retry = 0; retry < MPS_DB_MAX_WAIT; retry++) {
                if ((mps_regread(sc, MPI2_HOST_INTERRUPT_STATUS_OFFSET) &
                    MPI2_HIS_SYS2IOC_DB_STATUS) == 0)
                        return (0);
                DELAY(2000);
        }
        return (ETIMEDOUT);
}

/* Wait for the chip to signal that the next word in its FIFO can be fetched */
static int
mps_wait_db_int(struct mps_softc *sc)
{
        int retry;

        for (retry = 0; retry < MPS_DB_MAX_WAIT; retry++) {
                if ((mps_regread(sc, MPI2_HOST_INTERRUPT_STATUS_OFFSET) &
                    MPI2_HIS_IOC2SYS_DB_STATUS) != 0)
                        return (0);
                DELAY(2000);
        }
        return (ETIMEDOUT);
}

/* Step through the synchronous command state machine, i.e. "Doorbell mode" */
static int
mps_request_sync(struct mps_softc *sc, void *req, MPI2_DEFAULT_REPLY *reply,
    int req_sz, int reply_sz, int timeout)
{
        uint32_t *data32;
        uint16_t *data16;
        int i, count, ioc_sz, residual;

        /* Step 1 */
        mps_regwrite(sc, MPI2_HOST_INTERRUPT_STATUS_OFFSET, 0x0);

        /* Step 2 */
        if (mps_regread(sc, MPI2_DOORBELL_OFFSET) & MPI2_DOORBELL_USED)
                return (EBUSY);

        /* Step 3
         * Announce that a message is coming through the doorbell.  Messages
         * are pushed at 32bit words, so round up if needed.
         */
        count = (req_sz + 3) / 4;
        mps_regwrite(sc, MPI2_DOORBELL_OFFSET,
            (MPI2_FUNCTION_HANDSHAKE << MPI2_DOORBELL_FUNCTION_SHIFT) |
            (count << MPI2_DOORBELL_ADD_DWORDS_SHIFT));

        /* Step 4 */
        if (mps_wait_db_int(sc) ||
            (mps_regread(sc, MPI2_DOORBELL_OFFSET) & MPI2_DOORBELL_USED) == 0) {
                mps_dprint(sc, MPS_FAULT, "Doorbell failed to activate\n");
                return (ENXIO);
        }
        mps_regwrite(sc, MPI2_HOST_INTERRUPT_STATUS_OFFSET, 0x0);
        if (mps_wait_db_ack(sc) != 0) {
                mps_dprint(sc, MPS_FAULT, "Doorbell handshake failed\n");
                return (ENXIO);
        }

        /* Step 5 */
        /* Clock out the message data synchronously in 32-bit dwords*/
        data32 = (uint32_t *)req;
        for (i = 0; i < count; i++) {
                mps_regwrite(sc, MPI2_DOORBELL_OFFSET, data32[i]);
                if (mps_wait_db_ack(sc) != 0) {
                        mps_dprint(sc, MPS_FAULT,
                            "Timeout while writing doorbell\n");
                        return (ENXIO);
                }
        }

        /* Step 6 */
        /* Clock in the reply in 16-bit words.  The total length of the
         * message is always in the 4th byte, so clock out the first 2 words
         * manually, then loop the rest.
         */
        data16 = (uint16_t *)reply;
        if (mps_wait_db_int(sc) != 0) {
                mps_dprint(sc, MPS_FAULT, "Timeout reading doorbell 0\n");
                return (ENXIO);
        }
        data16[0] =
            mps_regread(sc, MPI2_DOORBELL_OFFSET) & MPI2_DOORBELL_DATA_MASK;
        mps_regwrite(sc, MPI2_HOST_INTERRUPT_STATUS_OFFSET, 0x0);
        if (mps_wait_db_int(sc) != 0) {
                mps_dprint(sc, MPS_FAULT, "Timeout reading doorbell 1\n");
                return (ENXIO);
        }
        data16[1] =
            mps_regread(sc, MPI2_DOORBELL_OFFSET) & MPI2_DOORBELL_DATA_MASK;
        mps_regwrite(sc, MPI2_HOST_INTERRUPT_STATUS_OFFSET, 0x0);

        /* Number of 32bit words in the message */
        ioc_sz = reply->MsgLength;

        /*
         * Figure out how many 16bit words to clock in without overrunning.
         * The precision loss with dividing reply_sz can safely be
         * ignored because the messages can only be multiples of 32bits.
         */
        residual = 0;
        count = MIN((reply_sz / 4), ioc_sz) * 2;
        if (count < ioc_sz * 2) {
                residual = ioc_sz * 2 - count;
                mps_dprint(sc, MPS_FAULT, "Driver error, throwing away %d "
                    "residual message words\n", residual);
        }

        for (i = 2; i < count; i++) {
                if (mps_wait_db_int(sc) != 0) {
                        mps_dprint(sc, MPS_FAULT,
                            "Timeout reading doorbell %d\n", i);
                        return (ENXIO);
                }
                data16[i] = mps_regread(sc, MPI2_DOORBELL_OFFSET) &
                    MPI2_DOORBELL_DATA_MASK;
                mps_regwrite(sc, MPI2_HOST_INTERRUPT_STATUS_OFFSET, 0x0);
        }

        /*
         * Pull out residual words that won't fit into the provided buffer.
         * This keeps the chip from hanging due to a driver programming
         * error.
         */
        while (residual--) {
                if (mps_wait_db_int(sc) != 0) {
                        mps_dprint(sc, MPS_FAULT,
                            "Timeout reading doorbell\n");
                        return (ENXIO);
                }
                (void)mps_regread(sc, MPI2_DOORBELL_OFFSET);
                mps_regwrite(sc, MPI2_HOST_INTERRUPT_STATUS_OFFSET, 0x0);
        }

        /* Step 7 */
        if (mps_wait_db_int(sc) != 0) {
                mps_dprint(sc, MPS_FAULT, "Timeout waiting to exit doorbell\n");
                return (ENXIO);
        }
        if (mps_regread(sc, MPI2_DOORBELL_OFFSET) & MPI2_DOORBELL_USED)
                mps_dprint(sc, MPS_FAULT, "Warning, doorbell still active\n");
        mps_regwrite(sc, MPI2_HOST_INTERRUPT_STATUS_OFFSET, 0x0);

        return (0);
}

static void
mps_enqueue_request(struct mps_softc *sc, struct mps_command *cm)
{

        mps_dprint(sc, MPS_TRACE, "%s SMID %u cm %p ccb %p\n", __func__,
            cm->cm_desc.Default.SMID, cm, cm->cm_ccb);

        if ((sc->mps_flags & MPS_FLAGS_ATTACH_DONE) &&
            !(sc->mps_flags & MPS_FLAGS_SHUTDOWN))
                KKASSERT(lockowned(&sc->mps_lock));

        if (++sc->io_cmds_active > sc->io_cmds_highwater)
                sc->io_cmds_highwater++;

        mps_regwrite(sc, MPI2_REQUEST_DESCRIPTOR_POST_LOW_OFFSET,
            cm->cm_desc.Words.Low);
        mps_regwrite(sc, MPI2_REQUEST_DESCRIPTOR_POST_HIGH_OFFSET,
            cm->cm_desc.Words.High);
}

/*
 * Just the FACTS, ma'am.
 */
static int
mps_get_iocfacts(struct mps_softc *sc, MPI2_IOC_FACTS_REPLY *facts)
{
        MPI2_DEFAULT_REPLY *reply;
        MPI2_IOC_FACTS_REQUEST request;
        int error, req_sz, reply_sz;

        mps_dprint(sc, MPS_TRACE, "%s\n", __func__);

        req_sz = sizeof(MPI2_IOC_FACTS_REQUEST);
        reply_sz = sizeof(MPI2_IOC_FACTS_REPLY);
        reply = (MPI2_DEFAULT_REPLY *)facts;

        bzero(&request, req_sz);
        request.Function = MPI2_FUNCTION_IOC_FACTS;
        error = mps_request_sync(sc, &request, reply, req_sz, reply_sz, 5);

        return (error);
}

static int
mps_get_portfacts(struct mps_softc *sc, MPI2_PORT_FACTS_REPLY *facts, int port)
{
        MPI2_PORT_FACTS_REQUEST *request;
        MPI2_PORT_FACTS_REPLY *reply;
        struct mps_command *cm;
        int error;

        mps_dprint(sc, MPS_TRACE, "%s\n", __func__);

        if ((cm = mps_alloc_command(sc)) == NULL)
                return (EBUSY);
        request = (MPI2_PORT_FACTS_REQUEST *)cm->cm_req;
        request->Function = MPI2_FUNCTION_PORT_FACTS;
        request->PortNumber = port;
        cm->cm_desc.Default.RequestFlags = MPI2_REQ_DESCRIPT_FLAGS_DEFAULT_TYPE;
        cm->cm_data = NULL;
        error = mps_request_polled(sc, cm);
        reply = (MPI2_PORT_FACTS_REPLY *)cm->cm_reply;
        if (reply == NULL) {
                mps_printf(sc, "%s NULL reply\n", __func__);
                goto done;
        }
        if ((reply->IOCStatus & MPI2_IOCSTATUS_MASK) != MPI2_IOCSTATUS_SUCCESS) {
                mps_printf(sc,
                    "%s error %d iocstatus 0x%x iocloginfo 0x%x type 0x%x\n",
                    __func__, error, reply->IOCStatus, reply->IOCLogInfo,
                    reply->PortType);
                error = ENXIO;
        }
        bcopy(reply, facts, sizeof(MPI2_PORT_FACTS_REPLY));
done:
        mps_free_command(sc, cm);

        return (error);
}

static int
mps_send_iocinit(struct mps_softc *sc)
{
        MPI2_IOC_INIT_REQUEST   init;
        MPI2_DEFAULT_REPLY      reply;
        int req_sz, reply_sz, error;

        mps_dprint(sc, MPS_TRACE, "%s\n", __func__);

        req_sz = sizeof(MPI2_IOC_INIT_REQUEST);
        reply_sz = sizeof(MPI2_IOC_INIT_REPLY);
        bzero(&init, req_sz);
        bzero(&reply, reply_sz);

        /*
         * Fill in the init block.  Note that most addresses are
         * deliberately in the lower 32bits of memory.  This is a micro-
         * optimzation for PCI/PCIX, though it's not clear if it helps PCIe.
         */
        init.Function = MPI2_FUNCTION_IOC_INIT;
        init.WhoInit = MPI2_WHOINIT_HOST_DRIVER;
        init.MsgVersion = MPI2_VERSION;
        init.HeaderVersion = MPI2_HEADER_VERSION;
        init.SystemRequestFrameSize = sc->facts->IOCRequestFrameSize;
        init.ReplyDescriptorPostQueueDepth = sc->pqdepth;
        init.ReplyFreeQueueDepth = sc->fqdepth;
        init.SenseBufferAddressHigh = 0;
        init.SystemReplyAddressHigh = 0;
        init.SystemRequestFrameBaseAddress.High = 0;
        init.SystemRequestFrameBaseAddress.Low = (uint32_t)sc->req_busaddr;
        init.ReplyDescriptorPostQueueAddress.High = 0;
        init.ReplyDescriptorPostQueueAddress.Low = (uint32_t)sc->post_busaddr;
        init.ReplyFreeQueueAddress.High = 0;
        init.ReplyFreeQueueAddress.Low = (uint32_t)sc->free_busaddr;
        init.TimeStamp.High = 0;
        init.TimeStamp.Low = (uint32_t)time_uptime;

        error = mps_request_sync(sc, &init, &reply, req_sz, reply_sz, 5);
        if ((reply.IOCStatus & MPI2_IOCSTATUS_MASK) != MPI2_IOCSTATUS_SUCCESS)
                error = ENXIO;

        mps_dprint(sc, MPS_INFO, "IOCInit status= 0x%x\n", reply.IOCStatus);
        return (error);
}

void
mps_memaddr_cb(void *arg, bus_dma_segment_t *segs, int nsegs, int error)
{
        bus_addr_t *addr;

        addr = arg;
        *addr = segs[0].ds_addr;
}

static int
mps_alloc_queues(struct mps_softc *sc)
{
        bus_addr_t queues_busaddr;
        uint8_t *queues;
        int qsize, fqsize, pqsize;

        /*
         * The reply free queue contains 4 byte entries in multiples of 16 and
         * aligned on a 16 byte boundary. There must always be an unused entry.
         * This queue supplies fresh reply frames for the firmware to use.
         *
         * The reply descriptor post queue contains 8 byte entries in
         * multiples of 16 and aligned on a 16 byte boundary.  This queue
         * contains filled-in reply frames sent from the firmware to the host.
         *
         * These two queues are allocated together for simplicity.
         */
        sc->fqdepth = roundup2((sc->num_replies + 1), 16);
        sc->pqdepth = roundup2((sc->num_replies + 1), 16);
        fqsize= sc->fqdepth * 4;
        pqsize = sc->pqdepth * 8;
        qsize = fqsize + pqsize;

        if (bus_dma_tag_create( sc->mps_parent_dmat,    /* parent */
                                16, 0,                  /* algnmnt, boundary */
                                BUS_SPACE_MAXADDR_32BIT,/* lowaddr */
                                BUS_SPACE_MAXADDR,      /* highaddr */
                                qsize,                  /* maxsize */
                                1,                      /* nsegments */
                                qsize,                  /* maxsegsize */
                                0,                      /* flags */
                                &sc->queues_dmat)) {
                device_printf(sc->mps_dev, "Cannot allocate queues DMA tag\n");
                return (ENOMEM);
        }
        if (bus_dmamem_alloc(sc->queues_dmat, (void **)&queues, BUS_DMA_NOWAIT,
            &sc->queues_map)) {
                device_printf(sc->mps_dev, "Cannot allocate queues memory\n");
                return (ENOMEM);
        }
        bzero(queues, qsize);
        bus_dmamap_load(sc->queues_dmat, sc->queues_map, queues, qsize,
            mps_memaddr_cb, &queues_busaddr, 0);

        sc->free_queue = (uint32_t *)queues;
        sc->free_busaddr = queues_busaddr;
        sc->post_queue = (MPI2_REPLY_DESCRIPTORS_UNION *)(queues + fqsize);
        sc->post_busaddr = queues_busaddr + fqsize;

        return (0);
}

static int
mps_alloc_replies(struct mps_softc *sc)
{
        int rsize, num_replies;

        /*
         * sc->num_replies should be one less than sc->fqdepth.  We need to
         * allocate space for sc->fqdepth replies, but only sc->num_replies
         * replies can be used at once.
         */
        num_replies = max(sc->fqdepth, sc->num_replies);

        rsize = sc->facts->ReplyFrameSize * num_replies * 4;
        if (bus_dma_tag_create( sc->mps_parent_dmat,    /* parent */
                                4, 0,                   /* algnmnt, boundary */
                                BUS_SPACE_MAXADDR_32BIT,/* lowaddr */
                                BUS_SPACE_MAXADDR,      /* highaddr */
                                rsize,                  /* maxsize */
                                1,                      /* nsegments */
                                rsize,                  /* maxsegsize */
                                0,                      /* flags */
                                &sc->reply_dmat)) {
                device_printf(sc->mps_dev, "Cannot allocate replies DMA tag\n");
                return (ENOMEM);
        }
        if (bus_dmamem_alloc(sc->reply_dmat, (void **)&sc->reply_frames,
            BUS_DMA_NOWAIT, &sc->reply_map)) {
                device_printf(sc->mps_dev, "Cannot allocate replies memory\n");
                return (ENOMEM);
        }
        bzero(sc->reply_frames, rsize);
        bus_dmamap_load(sc->reply_dmat, sc->reply_map, sc->reply_frames, rsize,
            mps_memaddr_cb, &sc->reply_busaddr, 0);

        return (0);
}

static int
mps_alloc_requests(struct mps_softc *sc)
{
        struct mps_command *cm;
        struct mps_chain *chain;
        int i, rsize, nsegs;

        rsize = sc->facts->IOCRequestFrameSize * sc->num_reqs * 4;
        if (bus_dma_tag_create( sc->mps_parent_dmat,    /* parent */
                                16, 0,                  /* algnmnt, boundary */
                                BUS_SPACE_MAXADDR_32BIT,/* lowaddr */
                                BUS_SPACE_MAXADDR,      /* highaddr */
                                rsize,                  /* maxsize */
                                1,                      /* nsegments */
                                rsize,                  /* maxsegsize */
                                0,                      /* flags */
                                &sc->req_dmat)) {
                device_printf(sc->mps_dev, "Cannot allocate request DMA tag\n");
                return (ENOMEM);
        }
        if (bus_dmamem_alloc(sc->req_dmat, (void **)&sc->req_frames,
            BUS_DMA_NOWAIT, &sc->req_map)) {
                device_printf(sc->mps_dev, "Cannot allocate request memory\n");
                return (ENOMEM);
        }
        bzero(sc->req_frames, rsize);
        bus_dmamap_load(sc->req_dmat, sc->req_map, sc->req_frames, rsize,
            mps_memaddr_cb, &sc->req_busaddr, 0);

        rsize = sc->facts->IOCRequestFrameSize * sc->max_chains * 4;
        if (bus_dma_tag_create( sc->mps_parent_dmat,    /* parent */
                                16, 0,                  /* algnmnt, boundary */
                                BUS_SPACE_MAXADDR_32BIT,/* lowaddr */
                                BUS_SPACE_MAXADDR,      /* highaddr */
                                rsize,                  /* maxsize */
                                1,                      /* nsegments */
                                rsize,                  /* maxsegsize */
                                0,                      /* flags */
                                &sc->chain_dmat)) {
                device_printf(sc->mps_dev, "Cannot allocate chain DMA tag\n");
                return (ENOMEM);
        }
        if (bus_dmamem_alloc(sc->chain_dmat, (void **)&sc->chain_frames,
            BUS_DMA_NOWAIT, &sc->chain_map)) {
                device_printf(sc->mps_dev, "Cannot allocate chain memory\n");
                return (ENOMEM);
        }
        bzero(sc->chain_frames, rsize);
        bus_dmamap_load(sc->chain_dmat, sc->chain_map, sc->chain_frames, rsize,
            mps_memaddr_cb, &sc->chain_busaddr, 0);

        rsize = MPS_SENSE_LEN * sc->num_reqs;
        if (bus_dma_tag_create( sc->mps_parent_dmat,    /* parent */
                                1, 0,                   /* algnmnt, boundary */
                                BUS_SPACE_MAXADDR_32BIT,/* lowaddr */
                                BUS_SPACE_MAXADDR,      /* highaddr */
                                rsize,                  /* maxsize */
                                1,                      /* nsegments */
                                rsize,                  /* maxsegsize */
                                0,                      /* flags */
                                &sc->sense_dmat)) {
                device_printf(sc->mps_dev, "Cannot allocate sense DMA tag\n");
                return (ENOMEM);
        }
        if (bus_dmamem_alloc(sc->sense_dmat, (void **)&sc->sense_frames,
            BUS_DMA_NOWAIT, &sc->sense_map)) {
                device_printf(sc->mps_dev, "Cannot allocate sense memory\n");
                return (ENOMEM);
        }
        bzero(sc->sense_frames, rsize);
        bus_dmamap_load(sc->sense_dmat, sc->sense_map, sc->sense_frames, rsize,
            mps_memaddr_cb, &sc->sense_busaddr, 0);

        sc->chains = kmalloc(sizeof(struct mps_chain) * sc->max_chains, M_MPT2,
            M_WAITOK | M_ZERO);
        for (i = 0; i < sc->max_chains; i++) {
                chain = &sc->chains[i];
                chain->chain = (MPI2_SGE_IO_UNION *)(sc->chain_frames +
                    i * sc->facts->IOCRequestFrameSize * 4);
                chain->chain_busaddr = sc->chain_busaddr +
                    i * sc->facts->IOCRequestFrameSize * 4;
                mps_free_chain(sc, chain);
                sc->chain_free_lowwater++;
        }

        /* XXX Need to pick a more precise value */
        nsegs = (MAXPHYS / PAGE_SIZE) + 1;
        if (bus_dma_tag_create( sc->mps_parent_dmat,    /* parent */
                                1, 0,                   /* algnmnt, boundary */
                                BUS_SPACE_MAXADDR,      /* lowaddr */
                                BUS_SPACE_MAXADDR,      /* highaddr */
                                BUS_SPACE_MAXSIZE_32BIT,/* maxsize */
                                nsegs,                  /* nsegments */
                                BUS_SPACE_MAXSIZE_24BIT,/* maxsegsize */
                                BUS_DMA_ALLOCNOW,       /* flags */
                                &sc->buffer_dmat)) {
                device_printf(sc->mps_dev, "Cannot allocate buffer DMA tag\n");
                return (ENOMEM);
        }

        /*
         * SMID 0 cannot be used as a free command per the firmware spec.
         * Just drop that command instead of risking accounting bugs.
         */
        sc->commands = kmalloc(sizeof(struct mps_command) * sc->num_reqs,
            M_MPT2, M_WAITOK | M_ZERO);
        for (i = 1; i < sc->num_reqs; i++) {
                cm = &sc->commands[i];
                cm->cm_req = sc->req_frames +
                    i * sc->facts->IOCRequestFrameSize * 4;
                cm->cm_req_busaddr = sc->req_busaddr +
                    i * sc->facts->IOCRequestFrameSize * 4;
                cm->cm_sense = &sc->sense_frames[i];
                cm->cm_sense_busaddr = sc->sense_busaddr + i * MPS_SENSE_LEN;
                cm->cm_desc.Default.SMID = i;
                cm->cm_sc = sc;
                TAILQ_INIT(&cm->cm_chain_list);
                callout_init_mp(&cm->cm_callout);

                /* XXX Is a failure here a critical problem? */
                if (bus_dmamap_create(sc->buffer_dmat, 0, &cm->cm_dmamap) == 0)
                        if (i <= sc->facts->HighPriorityCredit)
                                mps_free_high_priority_command(sc, cm);
                        else
                                mps_free_command(sc, cm);
                else {
                        panic("failed to allocate command %d", i);
                        sc->num_reqs = i;
                        break;
                }
        }

        return (0);
}

static int
mps_init_queues(struct mps_softc *sc)
{
        int i;

        memset((uint8_t *)sc->post_queue, 0xff, sc->pqdepth * 8);

        /*
         * According to the spec, we need to use one less reply than we
         * have space for on the queue.  So sc->num_replies (the number we
         * use) should be less than sc->fqdepth (allocated size).
         */
        if (sc->num_replies >= sc->fqdepth)
                return (EINVAL);

        /*
         * Initialize all of the free queue entries.
         */
        for (i = 0; i < sc->fqdepth; i++)
                sc->free_queue[i] = sc->reply_busaddr + (i * sc->facts->ReplyFrameSize * 4);
        sc->replyfreeindex = sc->num_replies;

        return (0);
}

/* Get the driver parameter tunables.  Lowest priority are the driver defaults.
 * Next are the global settings, if they exist.  Highest are the per-unit
 * settings, if they exist.
 */
static void
mps_get_tunables(struct mps_softc *sc)
{
        char tmpstr[80];

        /* XXX default to some debugging for now */
        sc->mps_debug = MPS_FAULT;
#if 0 /* XXX swildner */
        sc->disable_msix = 0;
#endif
        sc->enable_msi = 1;
        sc->max_chains = MPS_CHAIN_FRAMES;

        /*
         * Grab the global variables.
         */
        TUNABLE_INT_FETCH("hw.mps.debug_level", &sc->mps_debug);
#if 0 /* XXX swildner */
        TUNABLE_INT_FETCH("hw.mps.disable_msix", &sc->disable_msix);
#endif
        TUNABLE_INT_FETCH("hw.mps.msi.enable", &sc->enable_msi);
        TUNABLE_INT_FETCH("hw.mps.max_chains", &sc->max_chains);

        /* Grab the unit-instance variables */
        ksnprintf(tmpstr, sizeof(tmpstr), "dev.mps.%d.debug_level",
            device_get_unit(sc->mps_dev));
        TUNABLE_INT_FETCH(tmpstr, &sc->mps_debug);

#if 0 /* XXX swildner */
        ksnprintf(tmpstr, sizeof(tmpstr), "dev.mps.%d.disable_msix",
            device_get_unit(sc->mps_dev));
        TUNABLE_INT_FETCH(tmpstr, &sc->disable_msix);
#endif

        ksnprintf(tmpstr, sizeof(tmpstr), "dev.mps.%d.enable_msi",
            device_get_unit(sc->mps_dev));
        TUNABLE_INT_FETCH(tmpstr, &sc->enable_msi);

        ksnprintf(tmpstr, sizeof(tmpstr), "dev.mps.%d.max_chains",
            device_get_unit(sc->mps_dev));
        TUNABLE_INT_FETCH(tmpstr, &sc->max_chains);
}

static void
mps_setup_sysctl(struct mps_softc *sc)
{
        struct sysctl_ctx_list  *sysctl_ctx = NULL;
        struct sysctl_oid       *sysctl_tree = NULL;
        char tmpstr[80], tmpstr2[80];

        /*
         * Setup the sysctl variable so the user can change the debug level
         * on the fly.
         */
        ksnprintf(tmpstr, sizeof(tmpstr), "MPS controller %d",
            device_get_unit(sc->mps_dev));
        ksnprintf(tmpstr2, sizeof(tmpstr2), "%d", device_get_unit(sc->mps_dev));

        sysctl_ctx_init(&sc->sysctl_ctx);
        sc->sysctl_tree = SYSCTL_ADD_NODE(&sc->sysctl_ctx,
            SYSCTL_STATIC_CHILDREN(_hw_mps), OID_AUTO, tmpstr2,
            CTLFLAG_RD, 0, tmpstr);
        if (sc->sysctl_tree == NULL)
                return;
        sysctl_ctx = &sc->sysctl_ctx;
        sysctl_tree = sc->sysctl_tree;

        SYSCTL_ADD_INT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree),
            OID_AUTO, "debug_level", CTLFLAG_RW, &sc->mps_debug, 0,
            "mps debug level");

#if 0 /* XXX swildner */
        SYSCTL_ADD_INT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree),
            OID_AUTO, "disable_msix", CTLFLAG_RD, &sc->disable_msix, 0,
            "Disable the use of MSI-X interrupts");
#endif

        SYSCTL_ADD_INT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree),
            OID_AUTO, "enable_msi", CTLFLAG_RD, &sc->enable_msi, 0,
            "Enable the use of MSI interrupts");

        SYSCTL_ADD_STRING(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree),
            OID_AUTO, "firmware_version", CTLFLAG_RW, &sc->fw_version,
            strlen(sc->fw_version), "firmware version");

        SYSCTL_ADD_STRING(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree),
            OID_AUTO, "driver_version", CTLFLAG_RW, MPS_DRIVER_VERSION,
            strlen(MPS_DRIVER_VERSION), "driver version");

        SYSCTL_ADD_INT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree),
            OID_AUTO, "io_cmds_active", CTLFLAG_RD,
            &sc->io_cmds_active, 0, "number of currently active commands");

        SYSCTL_ADD_INT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree),
            OID_AUTO, "io_cmds_highwater", CTLFLAG_RD,
            &sc->io_cmds_highwater, 0, "maximum active commands seen");

        SYSCTL_ADD_INT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree),
            OID_AUTO, "chain_free", CTLFLAG_RD,
            &sc->chain_free, 0, "number of free chain elements");

        SYSCTL_ADD_INT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree),
            OID_AUTO, "chain_free_lowwater", CTLFLAG_RD,
            &sc->chain_free_lowwater, 0,"lowest number of free chain elements");

        SYSCTL_ADD_INT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree),
            OID_AUTO, "max_chains", CTLFLAG_RD,
            &sc->max_chains, 0,"maximum chain frames that will be allocated");

#if 0 /* __FreeBSD_version >= 900030 */
        SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree),
            OID_AUTO, "chain_alloc_fail", CTLFLAG_RD,
            &sc->chain_alloc_fail, "chain allocation failures");
#endif //FreeBSD_version >= 900030
}

int
mps_attach(struct mps_softc *sc)
{
        int i, error;

        mps_get_tunables(sc);

        mps_dprint(sc, MPS_TRACE, "%s\n", __func__);

        lockinit(&sc->mps_lock, "MPT2SAS lock", 0, LK_CANRECURSE);
        callout_init_mp(&sc->periodic);
        TAILQ_INIT(&sc->event_list);

        if ((error = mps_transition_ready(sc)) != 0) {
                mps_printf(sc, "%s failed to transition ready\n", __func__);
                return (error);
        }

        sc->facts = kmalloc(sizeof(MPI2_IOC_FACTS_REPLY), M_MPT2,
            M_ZERO|M_WAITOK);
        if ((error = mps_get_iocfacts(sc, sc->facts)) != 0)
                return (error);

        mps_print_iocfacts(sc, sc->facts);

        ksnprintf(sc->fw_version, sizeof(sc->fw_version),
            "%02d.%02d.%02d.%02d",
            sc->facts->FWVersion.Struct.Major,
            sc->facts->FWVersion.Struct.Minor,
            sc->facts->FWVersion.Struct.Unit,
            sc->facts->FWVersion.Struct.Dev);

        mps_printf(sc, "Firmware: %s, Driver: %s\n", sc->fw_version,
            MPS_DRIVER_VERSION);
        mps_printf(sc, "IOCCapabilities: %pb%i\n",
            "\20" "\3ScsiTaskFull" "\4DiagTrace" "\5SnapBuf" "\6ExtBuf"
            "\7EEDP" "\10BiDirTarg" "\11Multicast" "\14TransRetry" "\15IR"
            "\16EventReplay" "\17RaidAccel" "\20MSIXIndex" "\21HostDisc",
            sc->facts->IOCCapabilities);

        /*
         * If the chip doesn't support event replay then a hard reset will be
         * required to trigger a full discovery.  Do the reset here then
         * retransition to Ready.  A hard reset might have already been done,
         * but it doesn't hurt to do it again.
         */
        if ((sc->facts->IOCCapabilities &
            MPI2_IOCFACTS_CAPABILITY_EVENT_REPLAY) == 0) {
                mps_diag_reset(sc);
                if ((error = mps_transition_ready(sc)) != 0)
                        return (error);
        }

        /*
         * Set flag if IR Firmware is loaded.
         */
        if (sc->facts->IOCCapabilities &
            MPI2_IOCFACTS_CAPABILITY_INTEGRATED_RAID)
                sc->ir_firmware = 1;

        /*
         * Check if controller supports FW diag buffers and set flag to enable
         * each type.
         */
        if (sc->facts->IOCCapabilities &
            MPI2_IOCFACTS_CAPABILITY_DIAG_TRACE_BUFFER)
                sc->fw_diag_buffer_list[MPI2_DIAG_BUF_TYPE_TRACE].enabled =
                    TRUE;
        if (sc->facts->IOCCapabilities &
            MPI2_IOCFACTS_CAPABILITY_SNAPSHOT_BUFFER)
                sc->fw_diag_buffer_list[MPI2_DIAG_BUF_TYPE_SNAPSHOT].enabled =
                    TRUE;
        if (sc->facts->IOCCapabilities &
            MPI2_IOCFACTS_CAPABILITY_EXTENDED_BUFFER)
                sc->fw_diag_buffer_list[MPI2_DIAG_BUF_TYPE_EXTENDED].enabled =
                    TRUE;

        /*
         * Set flag if EEDP is supported and if TLR is supported.
         */
        if (sc->facts->IOCCapabilities & MPI2_IOCFACTS_CAPABILITY_EEDP)
                sc->eedp_enabled = TRUE;
        if (sc->facts->IOCCapabilities & MPI2_IOCFACTS_CAPABILITY_TLR)
                sc->control_TLR = TRUE;

        /*
         * Size the queues. Since the reply queues always need one free entry,
         * we'll just deduct one reply message here.
         */
        sc->num_reqs = MIN(MPS_REQ_FRAMES, sc->facts->RequestCredit);
        sc->num_replies = MIN(MPS_REPLY_FRAMES + MPS_EVT_REPLY_FRAMES,
            sc->facts->MaxReplyDescriptorPostQueueDepth) - 1;
        TAILQ_INIT(&sc->req_list);
        TAILQ_INIT(&sc->high_priority_req_list);
        TAILQ_INIT(&sc->chain_list);
        TAILQ_INIT(&sc->tm_list);

        if (((error = mps_alloc_queues(sc)) != 0) ||
            ((error = mps_alloc_replies(sc)) != 0) ||
            ((error = mps_alloc_requests(sc)) != 0)) {
                mps_printf(sc, "%s failed to alloc\n", __func__);
                mps_free(sc);
                return (error);
        }

        if (((error = mps_init_queues(sc)) != 0) ||
            ((error = mps_transition_operational(sc)) != 0)) {
                mps_printf(sc, "%s failed to transition operational\n", __func__);
                mps_free(sc);
                return (error);
        }

        /*
         * Finish the queue initialization.
         * These are set here instead of in mps_init_queues() because the
         * IOC resets these values during the state transition in
         * mps_transition_operational().  The free index is set to 1
         * because the corresponding index in the IOC is set to 0, and the
         * IOC treats the queues as full if both are set to the same value.
         * Hence the reason that the queue can't hold all of the possible
         * replies.
         */
        sc->replypostindex = 0;
        mps_regwrite(sc, MPI2_REPLY_FREE_HOST_INDEX_OFFSET, sc->replyfreeindex);
        mps_regwrite(sc, MPI2_REPLY_POST_HOST_INDEX_OFFSET, 0);

        sc->pfacts = kmalloc(sizeof(MPI2_PORT_FACTS_REPLY) *
            sc->facts->NumberOfPorts, M_MPT2, M_ZERO|M_WAITOK);
        for (i = 0; i < sc->facts->NumberOfPorts; i++) {
                if ((error = mps_get_portfacts(sc, &sc->pfacts[i], i)) != 0) {
                        mps_printf(sc, "%s failed to get portfacts for port %d\n",
                            __func__, i);
                        mps_free(sc);
                        return (error);
                }
                mps_print_portfacts(sc, &sc->pfacts[i]);
        }

        /* Attach the subsystems so they can prepare their event masks. */
        /* XXX Should be dynamic so that IM/IR and user modules can attach */
        if (((error = mps_attach_log(sc)) != 0) ||
            ((error = mps_attach_sas(sc)) != 0) ||
            ((error = mps_attach_user(sc)) != 0)) {
                mps_printf(sc, "%s failed to attach all subsystems: error %d\n",
                    __func__, error);
                mps_free(sc);
                return (error);
        }

        if ((error = mps_pci_setup_interrupts(sc)) != 0) {
                mps_printf(sc, "%s failed to setup interrupts\n", __func__);
                mps_free(sc);
                return (error);
        }

        /*
         * The static page function currently read is ioc page8.  Others can be
         * added in future.
         */
        mps_base_static_config_pages(sc);

        /* Start the periodic watchdog check on the IOC Doorbell */
        mps_periodic(sc);

        /*
         * The portenable will kick off discovery events that will drive the
         * rest of the initialization process.  The CAM/SAS module will
         * hold up the boot sequence until discovery is complete.
         */
        sc->mps_ich.ich_func = mps_startup;
        sc->mps_ich.ich_arg = sc;
        sc->mps_ich.ich_desc = "mps";
        if (config_intrhook_establish(&sc->mps_ich) != 0) {
                mps_dprint(sc, MPS_FAULT, "Cannot establish MPS config hook\n");
                error = EINVAL;
        }

        /*
         * Allow IR to shutdown gracefully when shutdown occurs.
         */
        sc->shutdown_eh = EVENTHANDLER_REGISTER(shutdown_final,
            mpssas_ir_shutdown, sc, SHUTDOWN_PRI_DEFAULT);

        if (sc->shutdown_eh == NULL)
                mps_dprint(sc, MPS_FAULT, "shutdown event registration "
                    "failed\n");

        mps_setup_sysctl(sc);

        sc->mps_flags |= MPS_FLAGS_ATTACH_DONE;

        return (error);
}

/* Run through any late-start handlers. */
static void
mps_startup(void *arg)
{
        struct mps_softc *sc;

        sc = (struct mps_softc *)arg;

        mps_lock(sc);
        mps_unmask_intr(sc);
        /* initialize device mapping tables */
        mps_mapping_initialize(sc);
        mpssas_startup(sc);
        mps_unlock(sc);
}

/* Periodic watchdog.  Is called with the driver lock already held. */
static void
mps_periodic(void *arg)
{
        struct mps_softc *sc;
        uint32_t db;

        sc = (struct mps_softc *)arg;
        mps_lock(sc);
        if (sc->mps_flags & MPS_FLAGS_SHUTDOWN) {
                mps_unlock(sc);
                return;
        }

        db = mps_regread(sc, MPI2_DOORBELL_OFFSET);
        if ((db & MPI2_IOC_STATE_MASK) == MPI2_IOC_STATE_FAULT) {
                device_printf(sc->mps_dev, "IOC Fault 0x%08x, Resetting\n", db);

                mps_reinit(sc);
        }

        callout_reset(&sc->periodic, MPS_PERIODIC_DELAY * hz, mps_periodic, sc);
        mps_unlock(sc);
}

static void
mps_log_evt_handler(struct mps_softc *sc, uintptr_t data,
    MPI2_EVENT_NOTIFICATION_REPLY *event)
{
        MPI2_EVENT_DATA_LOG_ENTRY_ADDED *entry;

        mps_print_event(sc, event);

        switch (event->Event) {
        case MPI2_EVENT_LOG_DATA:
                device_printf(sc->mps_dev, "MPI2_EVENT_LOG_DATA:\n");
                hexdump(event->EventData, event->EventDataLength, NULL, 0);
                break;
        case MPI2_EVENT_LOG_ENTRY_ADDED:
                entry = (MPI2_EVENT_DATA_LOG_ENTRY_ADDED *)event->EventData;
                mps_dprint(sc, MPS_INFO, "MPI2_EVENT_LOG_ENTRY_ADDED event "
                    "0x%x Sequence %d:\n", entry->LogEntryQualifier,
                     entry->LogSequence);
                break;
        default:
                break;
        }
        return;
}

static int
mps_attach_log(struct mps_softc *sc)
{
        uint8_t events[16];

        bzero(events, 16);
        setbit(events, MPI2_EVENT_LOG_DATA);
        setbit(events, MPI2_EVENT_LOG_ENTRY_ADDED);

        mps_register_events(sc, events, mps_log_evt_handler, NULL,
            &sc->mps_log_eh);

        return (0);
}

static int
mps_detach_log(struct mps_softc *sc)
{

        if (sc->mps_log_eh != NULL)
                mps_deregister_events(sc, sc->mps_log_eh);
        return (0);
}

/*
 * Free all of the driver resources and detach submodules.  Should be called
 * without the lock held.
 */
int
mps_free(struct mps_softc *sc)
{
        struct mps_command *cm;
        int i, error;

        /* Turn off the watchdog */
        mps_lock(sc);
        sc->mps_flags |= MPS_FLAGS_SHUTDOWN;
        mps_unlock(sc);
        callout_terminate(&sc->periodic);

        if (((error = mps_detach_log(sc)) != 0) ||
            ((error = mps_detach_sas(sc)) != 0))
                return (error);

        mps_detach_user(sc);

        /* Put the IOC back in the READY state. */
        mps_lock(sc);
        if ((error = mps_transition_ready(sc)) != 0) {
                mps_unlock(sc);
                return (error);
        }
        mps_unlock(sc);

        if (sc->facts != NULL)
                kfree(sc->facts, M_MPT2);

        if (sc->pfacts != NULL)
                kfree(sc->pfacts, M_MPT2);

        if (sc->post_busaddr != 0)
                bus_dmamap_unload(sc->queues_dmat, sc->queues_map);
        if (sc->post_queue != NULL)
                bus_dmamem_free(sc->queues_dmat, sc->post_queue,
                    sc->queues_map);
        if (sc->queues_dmat != NULL)
                bus_dma_tag_destroy(sc->queues_dmat);

        if (sc->chain_busaddr != 0)
                bus_dmamap_unload(sc->chain_dmat, sc->chain_map);
        if (sc->chain_frames != NULL)
                bus_dmamem_free(sc->chain_dmat, sc->chain_frames,sc->chain_map);
        if (sc->chain_dmat != NULL)
                bus_dma_tag_destroy(sc->chain_dmat);

        if (sc->sense_busaddr != 0)
                bus_dmamap_unload(sc->sense_dmat, sc->sense_map);
        if (sc->sense_frames != NULL)
                bus_dmamem_free(sc->sense_dmat, sc->sense_frames,sc->sense_map);
        if (sc->sense_dmat != NULL)
                bus_dma_tag_destroy(sc->sense_dmat);

        if (sc->reply_busaddr != 0)
                bus_dmamap_unload(sc->reply_dmat, sc->reply_map);
        if (sc->reply_frames != NULL)
                bus_dmamem_free(sc->reply_dmat, sc->reply_frames,sc->reply_map);
        if (sc->reply_dmat != NULL)
                bus_dma_tag_destroy(sc->reply_dmat);

        if (sc->req_busaddr != 0)
                bus_dmamap_unload(sc->req_dmat, sc->req_map);
        if (sc->req_frames != NULL)
                bus_dmamem_free(sc->req_dmat, sc->req_frames, sc->req_map);
        if (sc->req_dmat != NULL)
                bus_dma_tag_destroy(sc->req_dmat);

        if (sc->chains != NULL)
                kfree(sc->chains, M_MPT2);
        if (sc->commands != NULL) {
                for (i = 1; i < sc->num_reqs; i++) {
                        cm = &sc->commands[i];
                        bus_dmamap_destroy(sc->buffer_dmat, cm->cm_dmamap);
                }
                kfree(sc->commands, M_MPT2);
        }
        if (sc->buffer_dmat != NULL)
                bus_dma_tag_destroy(sc->buffer_dmat);

        if (sc->sysctl_tree != NULL)
                sysctl_ctx_free(&sc->sysctl_ctx);

        mps_mapping_free_memory(sc);

        /* Deregister the shutdown function */
        if (sc->shutdown_eh != NULL)
                EVENTHANDLER_DEREGISTER(shutdown_final, sc->shutdown_eh);

        lockuninit(&sc->mps_lock);

        return (0);
}

static __inline void
mps_complete_command(struct mps_command *cm)
{
        if (cm->cm_flags & MPS_CM_FLAGS_POLLED)
                cm->cm_flags |= MPS_CM_FLAGS_COMPLETE;

        if (cm->cm_complete != NULL) {
                mps_dprint(cm->cm_sc, MPS_TRACE,
                           "%s cm %p calling cm_complete %p data %p reply %p\n",
                           __func__, cm, cm->cm_complete, cm->cm_complete_data,
                           cm->cm_reply);
                cm->cm_complete(cm->cm_sc, cm);
        }

        if (cm->cm_flags & MPS_CM_FLAGS_WAKEUP) {
                mps_dprint(cm->cm_sc, MPS_TRACE, "%s: waking up %p\n",
                           __func__, cm);
                wakeup(cm);
        }

        if (cm->cm_sc->io_cmds_active != 0) {
                cm->cm_sc->io_cmds_active--;
        } else {
                mps_dprint(cm->cm_sc, MPS_INFO, "Warning: io_cmds_active is "
                    "out of sync - resynching to 0\n");
        }
}

void
mps_intr(void *data)
{
        struct mps_softc *sc;
        uint32_t status;

        sc = (struct mps_softc *)data;
        mps_dprint(sc, MPS_TRACE, "%s\n", __func__);

        /*
         * Check interrupt status register to flush the bus.  This is
         * needed for both INTx interrupts and driver-driven polling
         */
        status = mps_regread(sc, MPI2_HOST_INTERRUPT_STATUS_OFFSET);
        if ((status & MPI2_HIS_REPLY_DESCRIPTOR_INTERRUPT) == 0)
                return;

        mps_lock(sc);
        mps_intr_locked(data);
        mps_unlock(sc);
        return;
}

/*
 * In theory, MSI/MSIX interrupts shouldn't need to read any registers on the
 * chip.  Hopefully this theory is correct.
 */
void
mps_intr_msi(void *data)
{
        struct mps_softc *sc;

        sc = (struct mps_softc *)data;
        mps_dprint(sc, MPS_TRACE, "%s\n", __func__);
        mps_lock(sc);
        mps_intr_locked(data);
        mps_unlock(sc);
        return;
}

/*
 * The locking is overly broad and simplistic, but easy to deal with for now.
 */
void
mps_intr_locked(void *data)
{
        MPI2_REPLY_DESCRIPTORS_UNION *desc;
        struct mps_softc *sc;
        struct mps_command *cm = NULL;
        uint8_t flags;
        u_int pq;
        MPI2_DIAG_RELEASE_REPLY *rel_rep;
        mps_fw_diagnostic_buffer_t *pBuffer;

        sc = (struct mps_softc *)data;

        pq = sc->replypostindex;
        mps_dprint(sc, MPS_TRACE,
            "%s sc %p starting with replypostindex %u\n",
            __func__, sc, sc->replypostindex);

        for ( ;; ) {
                cm = NULL;
                desc = &sc->post_queue[sc->replypostindex];
                flags = desc->Default.ReplyFlags &
                    MPI2_RPY_DESCRIPT_FLAGS_TYPE_MASK;
                if ((flags == MPI2_RPY_DESCRIPT_FLAGS_UNUSED)
                 || (desc->Words.High == 0xffffffff))
                        break;

                /* increment the replypostindex now, so that event handlers
                 * and cm completion handlers which decide to do a diag
                 * reset can zero it without it getting incremented again
                 * afterwards, and we break out of this loop on the next
                 * iteration since the reply post queue has been cleared to
                 * 0xFF and all descriptors look unused (which they are).
                 */
                if (++sc->replypostindex >= sc->pqdepth)
                        sc->replypostindex = 0;

                switch (flags) {
                case MPI2_RPY_DESCRIPT_FLAGS_SCSI_IO_SUCCESS:
                        cm = &sc->commands[desc->SCSIIOSuccess.SMID];
                        cm->cm_reply = NULL;
                        break;
                case MPI2_RPY_DESCRIPT_FLAGS_ADDRESS_REPLY:
                {
                        uint32_t baddr;
                        uint8_t *reply;

                        /*
                         * Re-compose the reply address from the address
                         * sent back from the chip.  The ReplyFrameAddress
                         * is the lower 32 bits of the physical address of
                         * particular reply frame.  Convert that address to
                         * host format, and then use that to provide the
                         * offset against the virtual address base
                         * (sc->reply_frames).
                         */
                        baddr = le32toh(desc->AddressReply.ReplyFrameAddress);
                        reply = sc->reply_frames +
                                (baddr - ((uint32_t)sc->reply_busaddr));
                        /*
                         * Make sure the reply we got back is in a valid
                         * range.  If not, go ahead and panic here, since
                         * we'll probably panic as soon as we deference the
                         * reply pointer anyway.
                         */
                        if ((reply < sc->reply_frames)
                         || (reply > (sc->reply_frames +
                             (sc->fqdepth * sc->facts->ReplyFrameSize * 4)))) {
                                kprintf("%s: WARNING: reply %p out of range!\n",
                                       __func__, reply);
                                kprintf("%s: reply_frames %p, fqdepth %d, "
                                       "frame size %d\n", __func__,
                                       sc->reply_frames, sc->fqdepth,
                                       sc->facts->ReplyFrameSize * 4);
                                kprintf("%s: baddr %#x,\n", __func__, baddr);
                                panic("Reply address out of range");
                        }
                        if (desc->AddressReply.SMID == 0) {
                                if (((MPI2_DEFAULT_REPLY *)reply)->Function ==
                                    MPI2_FUNCTION_DIAG_BUFFER_POST) {
                                        /*
                                         * If SMID is 0 for Diag Buffer Post,
                                         * this implies that the reply is due to
                                         * a release function with a status that
                                         * the buffer has been released.  Set
                                         * the buffer flags accordingly.
                                         */
                                        rel_rep =
                                            (MPI2_DIAG_RELEASE_REPLY *)reply;
                                        if (rel_rep->IOCStatus ==
                                            MPI2_IOCSTATUS_DIAGNOSTIC_RELEASED)
                                            {
                                                pBuffer =
                                                    &sc->fw_diag_buffer_list[
                                                    rel_rep->BufferType];
                                                pBuffer->valid_data = TRUE;
                                                pBuffer->owned_by_firmware =
                                                    FALSE;
                                                pBuffer->immediate = FALSE;
                                        }
                                } else
                                        mps_dispatch_event(sc, baddr,
                                            (MPI2_EVENT_NOTIFICATION_REPLY *)
                                            reply);
                        } else {
                                cm = &sc->commands[desc->AddressReply.SMID];
                                cm->cm_reply = reply;
                                cm->cm_reply_data =
                                    desc->AddressReply.ReplyFrameAddress;
                        }
                        break;
                }
                case MPI2_RPY_DESCRIPT_FLAGS_TARGETASSIST_SUCCESS:
                case MPI2_RPY_DESCRIPT_FLAGS_TARGET_COMMAND_BUFFER:
                case MPI2_RPY_DESCRIPT_FLAGS_RAID_ACCELERATOR_SUCCESS:
                default:
                        /* Unhandled */
                        device_printf(sc->mps_dev, "Unhandled reply 0x%x\n",
                            desc->Default.ReplyFlags);
                        cm = NULL;
                        break;
                }

                if (cm != NULL)
                        mps_complete_command(cm);

                desc->Words.Low = 0xffffffff;
                desc->Words.High = 0xffffffff;
        }

        if (pq != sc->replypostindex) {
                mps_dprint(sc, MPS_TRACE,
                    "%s sc %p writing postindex %d\n",
                    __func__, sc, sc->replypostindex);
                mps_regwrite(sc, MPI2_REPLY_POST_HOST_INDEX_OFFSET, sc->replypostindex);
        }

        return;
}

static void
mps_dispatch_event(struct mps_softc *sc, uintptr_t data,
    MPI2_EVENT_NOTIFICATION_REPLY *reply)
{
        struct mps_event_handle *eh;
        int event, handled = 0;

        event = reply->Event;
        TAILQ_FOREACH(eh, &sc->event_list, eh_list) {
                if (isset(eh->mask, event)) {
                        eh->callback(sc, data, reply);
                        handled++;
                }
        }

        if (handled == 0)
                device_printf(sc->mps_dev, "Unhandled event 0x%x\n", event);

        /*
         * This is the only place that the event/reply should be freed.
         * Anything wanting to hold onto the event data should have
         * already copied it into their own storage.
         */
        mps_free_reply(sc, data);
}

static void
mps_reregister_events_complete(struct mps_softc *sc, struct mps_command *cm)
{
        mps_dprint(sc, MPS_TRACE, "%s\n", __func__);

        if (cm->cm_reply)
                mps_print_event(sc,
                        (MPI2_EVENT_NOTIFICATION_REPLY *)cm->cm_reply);

        mps_free_command(sc, cm);

        /* next, send a port enable */
        mpssas_startup(sc);
}

/*
 * For both register_events and update_events, the caller supplies a bitmap
 * of events that it _wants_.  These functions then turn that into a bitmask
 * suitable for the controller.
 */
int
mps_register_events(struct mps_softc *sc, uint8_t *mask,
    mps_evt_callback_t *cb, void *data, struct mps_event_handle **handle)
{
        struct mps_event_handle *eh;
        int error = 0;

        eh = kmalloc(sizeof(struct mps_event_handle), M_MPT2, M_WAITOK|M_ZERO);
        eh->callback = cb;
        eh->data = data;
        TAILQ_INSERT_TAIL(&sc->event_list, eh, eh_list);
        if (mask != NULL)
                error = mps_update_events(sc, eh, mask);
        *handle = eh;

        return (error);
}

int
mps_update_events(struct mps_softc *sc, struct mps_event_handle *handle,
    uint8_t *mask)
{
        MPI2_EVENT_NOTIFICATION_REQUEST *evtreq;
        MPI2_EVENT_NOTIFICATION_REPLY *reply;
        struct mps_command *cm;
        struct mps_event_handle *eh;
        int error, i;

        mps_dprint(sc, MPS_TRACE, "%s\n", __func__);

        if ((mask != NULL) && (handle != NULL))
                bcopy(mask, &handle->mask[0], 16);
        memset(sc->event_mask, 0xff, 16);

        TAILQ_FOREACH(eh, &sc->event_list, eh_list) {
                for (i = 0; i < 16; i++)
                        sc->event_mask[i] &= ~eh->mask[i];
        }

        if ((cm = mps_alloc_command(sc)) == NULL)
                return (EBUSY);
        evtreq = (MPI2_EVENT_NOTIFICATION_REQUEST *)cm->cm_req;
        evtreq->Function = MPI2_FUNCTION_EVENT_NOTIFICATION;
        evtreq->MsgFlags = 0;
        evtreq->SASBroadcastPrimitiveMasks = 0;
#ifdef MPS_DEBUG_ALL_EVENTS
        {
                u_char fullmask[16];
                memset(fullmask, 0x00, 16);
                bcopy(fullmask, (uint8_t *)&evtreq->EventMasks, 16);
        }
#else
                bcopy(sc->event_mask, (uint8_t *)&evtreq->EventMasks, 16);
#endif
        cm->cm_desc.Default.RequestFlags = MPI2_REQ_DESCRIPT_FLAGS_DEFAULT_TYPE;
        cm->cm_data = NULL;

        error = mps_request_polled(sc, cm);
        reply = (MPI2_EVENT_NOTIFICATION_REPLY *)cm->cm_reply;
        if ((reply == NULL) ||
            (reply->IOCStatus & MPI2_IOCSTATUS_MASK) != MPI2_IOCSTATUS_SUCCESS)
                error = ENXIO;
        mps_print_event(sc, reply);
        mps_dprint(sc, MPS_TRACE, "%s finished error %d\n", __func__, error);

        mps_free_command(sc, cm);
        return (error);
}

static int
mps_reregister_events(struct mps_softc *sc)
{
        MPI2_EVENT_NOTIFICATION_REQUEST *evtreq;
        struct mps_command *cm;
        struct mps_event_handle *eh;
        int error, i;

        mps_dprint(sc, MPS_TRACE, "%s\n", __func__);

        /* first, reregister events */

        memset(sc->event_mask, 0xff, 16);

        TAILQ_FOREACH(eh, &sc->event_list, eh_list) {
                for (i = 0; i < 16; i++)
                        sc->event_mask[i] &= ~eh->mask[i];
        }

        if ((cm = mps_alloc_command(sc)) == NULL)
                return (EBUSY);
        evtreq = (MPI2_EVENT_NOTIFICATION_REQUEST *)cm->cm_req;
        evtreq->Function = MPI2_FUNCTION_EVENT_NOTIFICATION;
        evtreq->MsgFlags = 0;
        evtreq->SASBroadcastPrimitiveMasks = 0;
#ifdef MPS_DEBUG_ALL_EVENTS
        {
                u_char fullmask[16];
                memset(fullmask, 0x00, 16);
                bcopy(fullmask, (uint8_t *)&evtreq->EventMasks, 16);
        }
#else
                bcopy(sc->event_mask, (uint8_t *)&evtreq->EventMasks, 16);
#endif
        cm->cm_desc.Default.RequestFlags = MPI2_REQ_DESCRIPT_FLAGS_DEFAULT_TYPE;
        cm->cm_data = NULL;
        cm->cm_complete = mps_reregister_events_complete;

        error = mps_map_command(sc, cm);

        mps_dprint(sc, MPS_TRACE, "%s finished with error %d\n", __func__, error);
        return (error);
}

int
mps_deregister_events(struct mps_softc *sc, struct mps_event_handle *handle)
{

        TAILQ_REMOVE(&sc->event_list, handle, eh_list);
        kfree(handle, M_MPT2);
        return (mps_update_events(sc, NULL, NULL));
}

/*
 * Add a chain element as the next SGE for the specified command.
 * Reset cm_sge and cm_sgesize to indicate all the available space.
 */
static int
mps_add_chain(struct mps_command *cm)
{
        MPI2_SGE_CHAIN32 *sgc;
        struct mps_chain *chain;
        int space;

        if (cm->cm_sglsize < MPS_SGC_SIZE)
                panic("MPS: Need SGE Error Code");

        chain = mps_alloc_chain(cm->cm_sc);
        if (chain == NULL)
                return (ENOBUFS);

        space = (int)cm->cm_sc->facts->IOCRequestFrameSize * 4;

        /*
         * Note: a double-linked list is used to make it easier to
         * walk for debugging.
         */
        TAILQ_INSERT_TAIL(&cm->cm_chain_list, chain, chain_link);

        sgc = (MPI2_SGE_CHAIN32 *)&cm->cm_sge->MpiChain;
        sgc->Length = space;
        sgc->NextChainOffset = 0;
        sgc->Flags = MPI2_SGE_FLAGS_CHAIN_ELEMENT;
        sgc->Address = chain->chain_busaddr;

        cm->cm_sge = (MPI2_SGE_IO_UNION *)&chain->chain->MpiSimple;
        cm->cm_sglsize = space;
        return (0);
}

/*
 * Add one scatter-gather element (chain, simple, transaction context)
 * to the scatter-gather list for a command.  Maintain cm_sglsize and
 * cm_sge as the remaining size and pointer to the next SGE to fill
 * in, respectively.
 */
int
mps_push_sge(struct mps_command *cm, void *sgep, size_t len, int segsleft)
{
        MPI2_SGE_TRANSACTION_UNION *tc = sgep;
        MPI2_SGE_SIMPLE64 *sge = sgep;
        int error, type;
        uint32_t saved_buf_len, saved_address_low, saved_address_high;

        type = (tc->Flags & MPI2_SGE_FLAGS_ELEMENT_MASK);

#ifdef INVARIANTS
        switch (type) {
        case MPI2_SGE_FLAGS_TRANSACTION_ELEMENT: {
                if (len != tc->DetailsLength + 4)
                        panic("TC %p length %u or %zu?", tc,
                            tc->DetailsLength + 4, len);
                }
                break;
        case MPI2_SGE_FLAGS_CHAIN_ELEMENT:
                /* Driver only uses 32-bit chain elements */
                if (len != MPS_SGC_SIZE)
                        panic("CHAIN %p length %u or %zu?", sgep,
                            MPS_SGC_SIZE, len);
                break;
        case MPI2_SGE_FLAGS_SIMPLE_ELEMENT:
                /* Driver only uses 64-bit SGE simple elements */
                if (len != MPS_SGE64_SIZE)
                        panic("SGE simple %p length %u or %zu?", sge,
                            MPS_SGE64_SIZE, len);
                if (((le32toh(sge->FlagsLength) >> MPI2_SGE_FLAGS_SHIFT) &
                    MPI2_SGE_FLAGS_ADDRESS_SIZE) == 0)
                        panic("SGE simple %p not marked 64-bit?", sge);

                break;
        default:
                panic("Unexpected SGE %p, flags %02x", tc, tc->Flags);
        }
#endif

        /*
         * case 1: 1 more segment, enough room for it
         * case 2: 2 more segments, enough room for both
         * case 3: >=2 more segments, only enough room for 1 and a chain
         * case 4: >=1 more segment, enough room for only a chain
         * case 5: >=1 more segment, no room for anything (error)
         */

        /*
         * There should be room for at least a chain element, or this
         * code is buggy.  Case (5).
         */
        if (cm->cm_sglsize < MPS_SGC_SIZE)
                panic("MPS: Need SGE Error Code");

        if (segsleft >= 2 &&
            cm->cm_sglsize >= len + MPS_SGC_SIZE &&
            cm->cm_sglsize < len + MPS_SGC_SIZE + MPS_SGE64_SIZE) {
                /*
                 * There are 2 or more segments left to add, and only
                 * enough room for 1 and a chain.  Case (3).
                 *
                 * Mark as last element in this chain if necessary.
                 */
                if (type == MPI2_SGE_FLAGS_SIMPLE_ELEMENT) {
                        sge->FlagsLength |= htole32(
                                MPI2_SGE_FLAGS_LAST_ELEMENT << MPI2_SGE_FLAGS_SHIFT);
                }

                /*
                 * Add the item then a chain.  Do the chain now,
                 * rather than on the next iteration, to simplify
                 * understanding the code.
                 */
                cm->cm_sglsize -= len;
                bcopy(sgep, cm->cm_sge, len);
                cm->cm_sge = (MPI2_SGE_IO_UNION *)((uintptr_t)cm->cm_sge + len);
                return (mps_add_chain(cm));
        }

        if (segsleft >= 1 && cm->cm_sglsize < len + MPS_SGC_SIZE) {
                /*
                 * 1 or more segment, enough room for only a chain.
                 * Hope the previous element wasn't a Simple entry
                 * that needed to be marked with
                 * MPI2_SGE_FLAGS_LAST_ELEMENT.  Case (4).
                 */
                if ((error = mps_add_chain(cm)) != 0)
                        return (error);
        }

#ifdef INVARIANTS
        /* Case 1: 1 more segment, enough room for it. */
        if (segsleft == 1 && cm->cm_sglsize < len)
                panic("1 seg left and no room? %u versus %zu",
                    cm->cm_sglsize, len);

        /* Case 2: 2 more segments, enough room for both */
        if (segsleft == 2 && cm->cm_sglsize < len + MPS_SGE64_SIZE)
                panic("2 segs left and no room? %u versus %zu",
                    cm->cm_sglsize, len);
#endif

        if (segsleft == 1 && type == MPI2_SGE_FLAGS_SIMPLE_ELEMENT) {
                /*
                 * If this is a bi-directional request, need to account for that
                 * here.  Save the pre-filled sge values.  These will be used
                 * either for the 2nd SGL or for a single direction SGL.  If
                 * cm_out_len is non-zero, this is a bi-directional request, so
                 * fill in the OUT SGL first, then the IN SGL, otherwise just
                 * fill in the IN SGL.  Note that at this time, when filling in
                 * 2 SGL's for a bi-directional request, they both use the same
                 * DMA buffer (same cm command).
                 */
                saved_buf_len = le32toh(sge->FlagsLength) & 0x00FFFFFF;
                saved_address_low = sge->Address.Low;
                saved_address_high = sge->Address.High;
                if (cm->cm_out_len) {
                        sge->FlagsLength = htole32(cm->cm_out_len |
                            ((uint32_t)(MPI2_SGE_FLAGS_SIMPLE_ELEMENT |
                            MPI2_SGE_FLAGS_END_OF_BUFFER |
                            MPI2_SGE_FLAGS_HOST_TO_IOC |
                            MPI2_SGE_FLAGS_64_BIT_ADDRESSING) <<
                            MPI2_SGE_FLAGS_SHIFT));
                        cm->cm_sglsize -= len;
                        bcopy(sgep, cm->cm_sge, len);
                        cm->cm_sge = (MPI2_SGE_IO_UNION *)((uintptr_t)cm->cm_sge
                            + len);
                }
                saved_buf_len |=
                    ((uint32_t)(MPI2_SGE_FLAGS_SIMPLE_ELEMENT |
                    MPI2_SGE_FLAGS_END_OF_BUFFER |
                    MPI2_SGE_FLAGS_LAST_ELEMENT |
                    MPI2_SGE_FLAGS_END_OF_LIST |
                    MPI2_SGE_FLAGS_64_BIT_ADDRESSING) <<
                    MPI2_SGE_FLAGS_SHIFT);
                if (cm->cm_flags & MPS_CM_FLAGS_DATAIN) {
                        saved_buf_len |=
                            ((uint32_t)(MPI2_SGE_FLAGS_IOC_TO_HOST) <<
                            MPI2_SGE_FLAGS_SHIFT);
                } else {
                        saved_buf_len |=
                            ((uint32_t)(MPI2_SGE_FLAGS_HOST_TO_IOC) <<
                            MPI2_SGE_FLAGS_SHIFT);
                }
                sge->FlagsLength = htole32(saved_buf_len);
                sge->Address.Low = saved_address_low;
                sge->Address.High = saved_address_high;
        }

        cm->cm_sglsize -= len;
        bcopy(sgep, cm->cm_sge, len);
        cm->cm_sge = (MPI2_SGE_IO_UNION *)((uintptr_t)cm->cm_sge + len);
        return (0);
}

/*
 * Add one dma segment to the scatter-gather list for a command.
 */
int
mps_add_dmaseg(struct mps_command *cm, vm_paddr_t pa, size_t len, u_int flags,
    int segsleft)
{
        MPI2_SGE_SIMPLE64 sge;

        /*
         * This driver always uses 64-bit address elements for simplicity.
         */
        bzero(&sge, sizeof(sge));
        flags |= MPI2_SGE_FLAGS_SIMPLE_ELEMENT |
            MPI2_SGE_FLAGS_64_BIT_ADDRESSING;
        sge.FlagsLength = htole32(len | (flags << MPI2_SGE_FLAGS_SHIFT));
        mps_from_u64(pa, &sge.Address);

        return (mps_push_sge(cm, &sge, sizeof sge, segsleft));
}

static void
mps_data_cb(void *arg, bus_dma_segment_t *segs, int nsegs, int error)
{
        struct mps_softc *sc;
        struct mps_command *cm;
        u_int i, dir, sflags;

        cm = (struct mps_command *)arg;
        sc = cm->cm_sc;

        /*
         * In this case, just print out a warning and let the chip tell the
         * user they did the wrong thing.
         */
        if ((cm->cm_max_segs != 0) && (nsegs > cm->cm_max_segs)) {
                mps_printf(sc, "%s: warning: busdma returned %d segments, "
                           "more than the %d allowed\n", __func__, nsegs,
                           cm->cm_max_segs);
        }

        /*
         * Set up DMA direction flags.  Bi-directional requests are also handled
         * here.  In that case, both direction flags will be set.
         */
        sflags = 0;
        if (cm->cm_flags & MPS_CM_FLAGS_SMP_PASS) {
                /*
                 * We have to add a special case for SMP passthrough, there
                 * is no easy way to generically handle it.  The first
                 * S/G element is used for the command (therefore the
                 * direction bit needs to be set).  The second one is used
                 * for the reply.  We'll leave it to the caller to make
                 * sure we only have two buffers.
                 */
                /*
                 * Even though the busdma man page says it doesn't make
                 * sense to have both direction flags, it does in this case.
                 * We have one s/g element being accessed in each direction.
                 */
                dir = BUS_DMASYNC_PREWRITE | BUS_DMASYNC_PREREAD;

                /*
                 * Set the direction flag on the first buffer in the SMP
                 * passthrough request.  We'll clear it for the second one.
                 */
                sflags |= MPI2_SGE_FLAGS_DIRECTION |
                          MPI2_SGE_FLAGS_END_OF_BUFFER;
        } else if (cm->cm_flags & MPS_CM_FLAGS_DATAOUT) {
                sflags |= MPI2_SGE_FLAGS_HOST_TO_IOC;
                dir = BUS_DMASYNC_PREWRITE;
        } else
                dir = BUS_DMASYNC_PREREAD;

        for (i = 0; i < nsegs; i++) {
                if ((cm->cm_flags & MPS_CM_FLAGS_SMP_PASS) && (i != 0)) {
                        sflags &= ~MPI2_SGE_FLAGS_DIRECTION;
                }
                error = mps_add_dmaseg(cm, segs[i].ds_addr, segs[i].ds_len,
                    sflags, nsegs - i);
                if (error != 0) {
                        /* Resource shortage, roll back! */
                        mps_dprint(sc, MPS_INFO, "out of chain frames\n");
                        cm->cm_flags |= MPS_CM_FLAGS_CHAIN_FAILED;
                        mps_complete_command(cm);
                        return;
                }
        }

        bus_dmamap_sync(sc->buffer_dmat, cm->cm_dmamap, dir);
        mps_enqueue_request(sc, cm);

        return;
}

static void
mps_data_cb2(void *arg, bus_dma_segment_t *segs, int nsegs, bus_size_t mapsize,
             int error)
{
        mps_data_cb(arg, segs, nsegs, error);
}

/*
 * This is the routine to enqueue commands ansynchronously.
 * Note that the only error path here is from bus_dmamap_load(), which can
 * return EINPROGRESS if it is waiting for resources.  Other than this, it's
 * assumed that if you have a command in-hand, then you have enough credits
 * to use it.
 */
int
mps_map_command(struct mps_softc *sc, struct mps_command *cm)
{
        int error = 0;

        if (cm->cm_flags & MPS_CM_FLAGS_USE_UIO) {
                error = bus_dmamap_load_uio(sc->buffer_dmat, cm->cm_dmamap,
                    &cm->cm_uio, mps_data_cb2, cm, 0);
        } else if ((cm->cm_data != NULL) && (cm->cm_length != 0)) {
                error = bus_dmamap_load(sc->buffer_dmat, cm->cm_dmamap,
                    cm->cm_data, cm->cm_length, mps_data_cb, cm, 0);
        } else {
                /* Add a zero-length element as needed */
                if (cm->cm_sge != NULL)
                        mps_add_dmaseg(cm, 0, 0, 0, 1);
                mps_enqueue_request(sc, cm);
        }

        return (error);
}

/*
 * This is the routine to enqueue commands synchronously.  An error of
 * EINPROGRESS from mps_map_command() is ignored since the command will
 * be executed and enqueued automatically.  Other errors come from msleep().
 */
int
mps_wait_command(struct mps_softc *sc, struct mps_command *cm, int timeout)
{
        int error;

        KKASSERT(lockowned(&sc->mps_lock));

        cm->cm_complete = NULL;
        cm->cm_flags |= MPS_CM_FLAGS_WAKEUP;
        error = mps_map_command(sc, cm);
        if ((error != 0) && (error != EINPROGRESS))
                return (error);
        error = lksleep(cm, &sc->mps_lock, 0, "mpswait", timeout*hz);
        if (error == EWOULDBLOCK)
                error = ETIMEDOUT;
        return (error);
}

/*
 * This is the routine to enqueue a command synchonously and poll for
 * completion.  Its use should be rare.
 */
int
mps_request_polled(struct mps_softc *sc, struct mps_command *cm)
{
        int error, timeout = 0;

        error = 0;

        cm->cm_flags |= MPS_CM_FLAGS_POLLED;
        cm->cm_complete = NULL;
        mps_map_command(sc, cm);

        while ((cm->cm_flags & MPS_CM_FLAGS_COMPLETE) == 0) {
                mps_intr_locked(sc);
                DELAY(50 * 1000);
                if (timeout++ > 1000) {
                        mps_dprint(sc, MPS_FAULT, "polling failed\n");
                        error = ETIMEDOUT;
                        break;
                }
        }

        return (error);
}

/*
 * The MPT driver had a verbose interface for config pages.  In this driver,
 * reduce it to much simplier terms, similar to the Linux driver.
 */
int
mps_read_config_page(struct mps_softc *sc, struct mps_config_params *params)
{
        MPI2_CONFIG_REQUEST *req;
        struct mps_command *cm;
        int error;

        if (sc->mps_flags & MPS_FLAGS_BUSY) {
                return (EBUSY);
        }

        cm = mps_alloc_command(sc);
        if (cm == NULL) {
                return (EBUSY);
        }

        req = (MPI2_CONFIG_REQUEST *)cm->cm_req;
        req->Function = MPI2_FUNCTION_CONFIG;
        req->Action = params->action;
        req->SGLFlags = 0;
        req->ChainOffset = 0;
        req->PageAddress = params->page_address;
        if (params->hdr.Struct.PageType == MPI2_CONFIG_PAGETYPE_EXTENDED) {
                MPI2_CONFIG_EXTENDED_PAGE_HEADER *hdr;

                hdr = &params->hdr.Ext;
                req->ExtPageType = hdr->ExtPageType;
                req->ExtPageLength = hdr->ExtPageLength;
                req->Header.PageType = MPI2_CONFIG_PAGETYPE_EXTENDED;
                req->Header.PageLength = 0; /* Must be set to zero */
                req->Header.PageNumber = hdr->PageNumber;
                req->Header.PageVersion = hdr->PageVersion;
        } else {
                MPI2_CONFIG_PAGE_HEADER *hdr;

                hdr = &params->hdr.Struct;
                req->Header.PageType = hdr->PageType;
                req->Header.PageNumber = hdr->PageNumber;
                req->Header.PageLength = hdr->PageLength;
                req->Header.PageVersion = hdr->PageVersion;
        }

        cm->cm_data = params->buffer;
        cm->cm_length = params->length;
        cm->cm_sge = &req->PageBufferSGE;
        cm->cm_sglsize = sizeof(MPI2_SGE_IO_UNION);
        cm->cm_flags = MPS_CM_FLAGS_SGE_SIMPLE | MPS_CM_FLAGS_DATAIN;
        cm->cm_desc.Default.RequestFlags = MPI2_REQ_DESCRIPT_FLAGS_DEFAULT_TYPE;

        cm->cm_complete_data = params;
        if (params->callback != NULL) {
                cm->cm_complete = mps_config_complete;
                return (mps_map_command(sc, cm));
        } else {
                error = mps_wait_command(sc, cm, 0);
                if (error) {
                        mps_dprint(sc, MPS_FAULT,
                            "Error %d reading config page\n", error);
                        mps_free_command(sc, cm);
                        return (error);
                }
                mps_config_complete(sc, cm);
        }

        return (0);
}

int
mps_write_config_page(struct mps_softc *sc, struct mps_config_params *params)
{
        return (EINVAL);
}

static void
mps_config_complete(struct mps_softc *sc, struct mps_command *cm)
{
        MPI2_CONFIG_REPLY *reply;
        struct mps_config_params *params;

        params = cm->cm_complete_data;

        if (cm->cm_data != NULL) {
                bus_dmamap_sync(sc->buffer_dmat, cm->cm_dmamap,
                    BUS_DMASYNC_POSTREAD);
                bus_dmamap_unload(sc->buffer_dmat, cm->cm_dmamap);
        }

        /*
         * XXX KDM need to do more error recovery?  This results in the
         * device in question not getting probed.
         */
        if ((cm->cm_flags & MPS_CM_FLAGS_ERROR_MASK) != 0) {
                params->status = MPI2_IOCSTATUS_BUSY;
                goto done;
        }

        reply = (MPI2_CONFIG_REPLY *)cm->cm_reply;
        if (reply == NULL) {
                params->status = MPI2_IOCSTATUS_BUSY;
                goto done;
        }
        params->status = reply->IOCStatus;
        if (params->hdr.Ext.ExtPageType != 0) {
                params->hdr.Ext.ExtPageType = reply->ExtPageType;
                params->hdr.Ext.ExtPageLength = reply->ExtPageLength;
        } else {
                params->hdr.Struct.PageType = reply->Header.PageType;
                params->hdr.Struct.PageNumber = reply->Header.PageNumber;
                params->hdr.Struct.PageLength = reply->Header.PageLength;
                params->hdr.Struct.PageVersion = reply->Header.PageVersion;
        }

done:
        mps_free_command(sc, cm);
        if (params->callback != NULL)
                params->callback(sc, params);

        return;
}