Linux 5.1.15

[linux/fpc-iii.git] / drivers / scsi / isci / remote_device.c

/*
 * This file is provided under a dual BSD/GPLv2 license.  When using or
 * redistributing this file, you may do so under either license.
 *
 * GPL LICENSE SUMMARY
 *
 * Copyright(c) 2008 - 2011 Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 * The full GNU General Public License is included in this distribution
 * in the file called LICENSE.GPL.
 *
 * BSD LICENSE
 *
 * Copyright(c) 2008 - 2011 Intel Corporation. All rights reserved.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   * 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.
 *   * Neither the name of Intel Corporation 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
 * OWNER 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.
 */
#include <scsi/sas.h>
#include <linux/bitops.h>
#include "isci.h"
#include "port.h"
#include "remote_device.h"
#include "request.h"
#include "remote_node_context.h"
#include "scu_event_codes.h"
#include "task.h"

#undef C
#define C(a) (#a)
const char *dev_state_name(enum sci_remote_device_states state)
{
        static const char * const strings[] = REMOTE_DEV_STATES;

        return strings[state];
}
#undef C

enum sci_status sci_remote_device_suspend(struct isci_remote_device *idev,
                                          enum sci_remote_node_suspension_reasons reason)
{
        return sci_remote_node_context_suspend(&idev->rnc, reason,
                                               SCI_SOFTWARE_SUSPEND_EXPECTED_EVENT);
}

/**
 * isci_remote_device_ready() - This function is called by the ihost when the
 *    remote device is ready. We mark the isci device as ready and signal the
 *    waiting proccess.
 * @ihost: our valid isci_host
 * @idev: remote device
 *
 */
static void isci_remote_device_ready(struct isci_host *ihost, struct isci_remote_device *idev)
{
        dev_dbg(&ihost->pdev->dev,
                "%s: idev = %p\n", __func__, idev);

        clear_bit(IDEV_IO_NCQERROR, &idev->flags);
        set_bit(IDEV_IO_READY, &idev->flags);
        if (test_and_clear_bit(IDEV_START_PENDING, &idev->flags))
                wake_up(&ihost->eventq);
}

static enum sci_status sci_remote_device_terminate_req(
        struct isci_host *ihost,
        struct isci_remote_device *idev,
        int check_abort,
        struct isci_request *ireq)
{
        if (!test_bit(IREQ_ACTIVE, &ireq->flags) ||
            (ireq->target_device != idev) ||
            (check_abort && !test_bit(IREQ_PENDING_ABORT, &ireq->flags)))
                return SCI_SUCCESS;

        dev_dbg(&ihost->pdev->dev,
                "%s: idev=%p; flags=%lx; req=%p; req target=%p\n",
                __func__, idev, idev->flags, ireq, ireq->target_device);

        set_bit(IREQ_ABORT_PATH_ACTIVE, &ireq->flags);

        return sci_controller_terminate_request(ihost, idev, ireq);
}

static enum sci_status sci_remote_device_terminate_reqs_checkabort(
        struct isci_remote_device *idev,
        int chk)
{
        struct isci_host *ihost = idev->owning_port->owning_controller;
        enum sci_status status  = SCI_SUCCESS;
        u32 i;

        for (i = 0; i < SCI_MAX_IO_REQUESTS; i++) {
                struct isci_request *ireq = ihost->reqs[i];
                enum sci_status s;

                s = sci_remote_device_terminate_req(ihost, idev, chk, ireq);
                if (s != SCI_SUCCESS)
                        status = s;
        }
        return status;
}

static bool isci_compare_suspendcount(
        struct isci_remote_device *idev,
        u32 localcount)
{
        smp_rmb();

        /* Check for a change in the suspend count, or the RNC
         * being destroyed.
         */
        return (localcount != idev->rnc.suspend_count)
            || sci_remote_node_context_is_being_destroyed(&idev->rnc);
}

static bool isci_check_reqterm(
        struct isci_host *ihost,
        struct isci_remote_device *idev,
        struct isci_request *ireq,
        u32 localcount)
{
        unsigned long flags;
        bool res;

        spin_lock_irqsave(&ihost->scic_lock, flags);
        res = isci_compare_suspendcount(idev, localcount)
                && !test_bit(IREQ_ABORT_PATH_ACTIVE, &ireq->flags);
        spin_unlock_irqrestore(&ihost->scic_lock, flags);

        return res;
}

static bool isci_check_devempty(
        struct isci_host *ihost,
        struct isci_remote_device *idev,
        u32 localcount)
{
        unsigned long flags;
        bool res;

        spin_lock_irqsave(&ihost->scic_lock, flags);
        res = isci_compare_suspendcount(idev, localcount)
                && idev->started_request_count == 0;
        spin_unlock_irqrestore(&ihost->scic_lock, flags);

        return res;
}

enum sci_status isci_remote_device_terminate_requests(
        struct isci_host *ihost,
        struct isci_remote_device *idev,
        struct isci_request *ireq)
{
        enum sci_status status = SCI_SUCCESS;
        unsigned long flags;
        u32 rnc_suspend_count;

        spin_lock_irqsave(&ihost->scic_lock, flags);

        if (isci_get_device(idev) == NULL) {
                dev_dbg(&ihost->pdev->dev, "%s: failed isci_get_device(idev=%p)\n",
                        __func__, idev);
                spin_unlock_irqrestore(&ihost->scic_lock, flags);
                status = SCI_FAILURE;
        } else {
                /* If already suspended, don't wait for another suspension. */
                smp_rmb();
                rnc_suspend_count
                        = sci_remote_node_context_is_suspended(&idev->rnc)
                                ? 0 : idev->rnc.suspend_count;

                dev_dbg(&ihost->pdev->dev,
                        "%s: idev=%p, ireq=%p; started_request_count=%d, "
                                "rnc_suspend_count=%d, rnc.suspend_count=%d"
                                "about to wait\n",
                        __func__, idev, ireq, idev->started_request_count,
                        rnc_suspend_count, idev->rnc.suspend_count);

                #define MAX_SUSPEND_MSECS 10000
                if (ireq) {
                        /* Terminate a specific TC. */
                        set_bit(IREQ_NO_AUTO_FREE_TAG, &ireq->flags);
                        sci_remote_device_terminate_req(ihost, idev, 0, ireq);
                        spin_unlock_irqrestore(&ihost->scic_lock, flags);
                        if (!wait_event_timeout(ihost->eventq,
                                                isci_check_reqterm(ihost, idev, ireq,
                                                                   rnc_suspend_count),
                                                msecs_to_jiffies(MAX_SUSPEND_MSECS))) {

                                dev_warn(&ihost->pdev->dev, "%s host%d timeout single\n",
                                         __func__, ihost->id);
                                dev_dbg(&ihost->pdev->dev,
                                         "%s: ******* Timeout waiting for "
                                         "suspend; idev=%p, current state %s; "
                                         "started_request_count=%d, flags=%lx\n\t"
                                         "rnc_suspend_count=%d, rnc.suspend_count=%d "
                                         "RNC: current state %s, current "
                                         "suspend_type %x dest state %d;\n"
                                         "ireq=%p, ireq->flags = %lx\n",
                                         __func__, idev,
                                         dev_state_name(idev->sm.current_state_id),
                                         idev->started_request_count, idev->flags,
                                         rnc_suspend_count, idev->rnc.suspend_count,
                                         rnc_state_name(idev->rnc.sm.current_state_id),
                                         idev->rnc.suspend_type,
                                         idev->rnc.destination_state,
                                         ireq, ireq->flags);
                        }
                        spin_lock_irqsave(&ihost->scic_lock, flags);
                        clear_bit(IREQ_NO_AUTO_FREE_TAG, &ireq->flags);
                        if (!test_bit(IREQ_ABORT_PATH_ACTIVE, &ireq->flags))
                                isci_free_tag(ihost, ireq->io_tag);
                        spin_unlock_irqrestore(&ihost->scic_lock, flags);
                } else {
                        /* Terminate all TCs. */
                        sci_remote_device_terminate_requests(idev);
                        spin_unlock_irqrestore(&ihost->scic_lock, flags);
                        if (!wait_event_timeout(ihost->eventq,
                                                isci_check_devempty(ihost, idev,
                                                                    rnc_suspend_count),
                                                msecs_to_jiffies(MAX_SUSPEND_MSECS))) {

                                dev_warn(&ihost->pdev->dev, "%s host%d timeout all\n",
                                         __func__, ihost->id);
                                dev_dbg(&ihost->pdev->dev,
                                        "%s: ******* Timeout waiting for "
                                        "suspend; idev=%p, current state %s; "
                                        "started_request_count=%d, flags=%lx\n\t"
                                        "rnc_suspend_count=%d, "
                                        "RNC: current state %s, "
                                        "rnc.suspend_count=%d, current "
                                        "suspend_type %x dest state %d\n",
                                        __func__, idev,
                                        dev_state_name(idev->sm.current_state_id),
                                        idev->started_request_count, idev->flags,
                                        rnc_suspend_count,
                                        rnc_state_name(idev->rnc.sm.current_state_id),
                                        idev->rnc.suspend_count,
                                        idev->rnc.suspend_type,
                                        idev->rnc.destination_state);
                        }
                }
                dev_dbg(&ihost->pdev->dev, "%s: idev=%p, wait done\n",
                        __func__, idev);
                isci_put_device(idev);
        }
        return status;
}

/**
* isci_remote_device_not_ready() - This function is called by the ihost when
*    the remote device is not ready. We mark the isci device as ready (not
*    "ready_for_io") and signal the waiting proccess.
* @isci_host: This parameter specifies the isci host object.
* @isci_device: This parameter specifies the remote device
*
* sci_lock is held on entrance to this function.
*/
static void isci_remote_device_not_ready(struct isci_host *ihost,
                                         struct isci_remote_device *idev,
                                         u32 reason)
{
        dev_dbg(&ihost->pdev->dev,
                "%s: isci_device = %p; reason = %d\n", __func__, idev, reason);

        switch (reason) {
        case SCIC_REMOTE_DEVICE_NOT_READY_SATA_SDB_ERROR_FIS_RECEIVED:
                set_bit(IDEV_IO_NCQERROR, &idev->flags);

                /* Suspend the remote device so the I/O can be terminated. */
                sci_remote_device_suspend(idev, SCI_SW_SUSPEND_NORMAL);

                /* Kill all outstanding requests for the device. */
                sci_remote_device_terminate_requests(idev);

                /* Fall through - into the default case... */
        default:
                clear_bit(IDEV_IO_READY, &idev->flags);
                break;
        }
}

/* called once the remote node context is ready to be freed.
 * The remote device can now report that its stop operation is complete. none
 */
static void rnc_destruct_done(void *_dev)
{
        struct isci_remote_device *idev = _dev;

        BUG_ON(idev->started_request_count != 0);
        sci_change_state(&idev->sm, SCI_DEV_STOPPED);
}

enum sci_status sci_remote_device_terminate_requests(
        struct isci_remote_device *idev)
{
        return sci_remote_device_terminate_reqs_checkabort(idev, 0);
}

enum sci_status sci_remote_device_stop(struct isci_remote_device *idev,
                                        u32 timeout)
{
        struct sci_base_state_machine *sm = &idev->sm;
        enum sci_remote_device_states state = sm->current_state_id;

        switch (state) {
        case SCI_DEV_INITIAL:
        case SCI_DEV_FAILED:
        case SCI_DEV_FINAL:
        default:
                dev_warn(scirdev_to_dev(idev), "%s: in wrong state: %s\n",
                         __func__, dev_state_name(state));
                return SCI_FAILURE_INVALID_STATE;
        case SCI_DEV_STOPPED:
                return SCI_SUCCESS;
        case SCI_DEV_STARTING:
                /* device not started so there had better be no requests */
                BUG_ON(idev->started_request_count != 0);
                sci_remote_node_context_destruct(&idev->rnc,
                                                      rnc_destruct_done, idev);
                /* Transition to the stopping state and wait for the
                 * remote node to complete being posted and invalidated.
                 */
                sci_change_state(sm, SCI_DEV_STOPPING);
                return SCI_SUCCESS;
        case SCI_DEV_READY:
        case SCI_STP_DEV_IDLE:
        case SCI_STP_DEV_CMD:
        case SCI_STP_DEV_NCQ:
        case SCI_STP_DEV_NCQ_ERROR:
        case SCI_STP_DEV_AWAIT_RESET:
        case SCI_SMP_DEV_IDLE:
        case SCI_SMP_DEV_CMD:
                sci_change_state(sm, SCI_DEV_STOPPING);
                if (idev->started_request_count == 0)
                        sci_remote_node_context_destruct(&idev->rnc,
                                                         rnc_destruct_done,
                                                         idev);
                else {
                        sci_remote_device_suspend(
                                idev, SCI_SW_SUSPEND_LINKHANG_DETECT);
                        sci_remote_device_terminate_requests(idev);
                }
                return SCI_SUCCESS;
        case SCI_DEV_STOPPING:
                /* All requests should have been terminated, but if there is an
                 * attempt to stop a device already in the stopping state, then
                 * try again to terminate.
                 */
                return sci_remote_device_terminate_requests(idev);
        case SCI_DEV_RESETTING:
                sci_change_state(sm, SCI_DEV_STOPPING);
                return SCI_SUCCESS;
        }
}

enum sci_status sci_remote_device_reset(struct isci_remote_device *idev)
{
        struct sci_base_state_machine *sm = &idev->sm;
        enum sci_remote_device_states state = sm->current_state_id;

        switch (state) {
        case SCI_DEV_INITIAL:
        case SCI_DEV_STOPPED:
        case SCI_DEV_STARTING:
        case SCI_SMP_DEV_IDLE:
        case SCI_SMP_DEV_CMD:
        case SCI_DEV_STOPPING:
        case SCI_DEV_FAILED:
        case SCI_DEV_RESETTING:
        case SCI_DEV_FINAL:
        default:
                dev_warn(scirdev_to_dev(idev), "%s: in wrong state: %s\n",
                         __func__, dev_state_name(state));
                return SCI_FAILURE_INVALID_STATE;
        case SCI_DEV_READY:
        case SCI_STP_DEV_IDLE:
        case SCI_STP_DEV_CMD:
        case SCI_STP_DEV_NCQ:
        case SCI_STP_DEV_NCQ_ERROR:
        case SCI_STP_DEV_AWAIT_RESET:
                sci_change_state(sm, SCI_DEV_RESETTING);
                return SCI_SUCCESS;
        }
}

enum sci_status sci_remote_device_reset_complete(struct isci_remote_device *idev)
{
        struct sci_base_state_machine *sm = &idev->sm;
        enum sci_remote_device_states state = sm->current_state_id;

        if (state != SCI_DEV_RESETTING) {
                dev_warn(scirdev_to_dev(idev), "%s: in wrong state: %s\n",
                         __func__, dev_state_name(state));
                return SCI_FAILURE_INVALID_STATE;
        }

        sci_change_state(sm, SCI_DEV_READY);
        return SCI_SUCCESS;
}

enum sci_status sci_remote_device_frame_handler(struct isci_remote_device *idev,
                                                     u32 frame_index)
{
        struct sci_base_state_machine *sm = &idev->sm;
        enum sci_remote_device_states state = sm->current_state_id;
        struct isci_host *ihost = idev->owning_port->owning_controller;
        enum sci_status status;

        switch (state) {
        case SCI_DEV_INITIAL:
        case SCI_DEV_STOPPED:
        case SCI_DEV_STARTING:
        case SCI_STP_DEV_IDLE:
        case SCI_SMP_DEV_IDLE:
        case SCI_DEV_FINAL:
        default:
                dev_warn(scirdev_to_dev(idev), "%s: in wrong state: %s\n",
                         __func__, dev_state_name(state));
                /* Return the frame back to the controller */
                sci_controller_release_frame(ihost, frame_index);
                return SCI_FAILURE_INVALID_STATE;
        case SCI_DEV_READY:
        case SCI_STP_DEV_NCQ_ERROR:
        case SCI_STP_DEV_AWAIT_RESET:
        case SCI_DEV_STOPPING:
        case SCI_DEV_FAILED:
        case SCI_DEV_RESETTING: {
                struct isci_request *ireq;
                struct ssp_frame_hdr hdr;
                void *frame_header;
                ssize_t word_cnt;

                status = sci_unsolicited_frame_control_get_header(&ihost->uf_control,
                                                                       frame_index,
                                                                       &frame_header);
                if (status != SCI_SUCCESS)
                        return status;

                word_cnt = sizeof(hdr) / sizeof(u32);
                sci_swab32_cpy(&hdr, frame_header, word_cnt);

                ireq = sci_request_by_tag(ihost, be16_to_cpu(hdr.tag));
                if (ireq && ireq->target_device == idev) {
                        /* The IO request is now in charge of releasing the frame */
                        status = sci_io_request_frame_handler(ireq, frame_index);
                } else {
                        /* We could not map this tag to a valid IO
                         * request Just toss the frame and continue
                         */
                        sci_controller_release_frame(ihost, frame_index);
                }
                break;
        }
        case SCI_STP_DEV_NCQ: {
                struct dev_to_host_fis *hdr;

                status = sci_unsolicited_frame_control_get_header(&ihost->uf_control,
                                                                       frame_index,
                                                                       (void **)&hdr);
                if (status != SCI_SUCCESS)
                        return status;

                if (hdr->fis_type == FIS_SETDEVBITS &&
                    (hdr->status & ATA_ERR)) {
                        idev->not_ready_reason = SCIC_REMOTE_DEVICE_NOT_READY_SATA_SDB_ERROR_FIS_RECEIVED;

                        /* TODO Check sactive and complete associated IO if any. */
                        sci_change_state(sm, SCI_STP_DEV_NCQ_ERROR);
                } else if (hdr->fis_type == FIS_REGD2H &&
                           (hdr->status & ATA_ERR)) {
                        /*
                         * Some devices return D2H FIS when an NCQ error is detected.
                         * Treat this like an SDB error FIS ready reason.
                         */
                        idev->not_ready_reason = SCIC_REMOTE_DEVICE_NOT_READY_SATA_SDB_ERROR_FIS_RECEIVED;
                        sci_change_state(&idev->sm, SCI_STP_DEV_NCQ_ERROR);
                } else
                        status = SCI_FAILURE;

                sci_controller_release_frame(ihost, frame_index);
                break;
        }
        case SCI_STP_DEV_CMD:
        case SCI_SMP_DEV_CMD:
                /* The device does not process any UF received from the hardware while
                 * in this state.  All unsolicited frames are forwarded to the io request
                 * object.
                 */
                status = sci_io_request_frame_handler(idev->working_request, frame_index);
                break;
        }

        return status;
}

static bool is_remote_device_ready(struct isci_remote_device *idev)
{

        struct sci_base_state_machine *sm = &idev->sm;
        enum sci_remote_device_states state = sm->current_state_id;

        switch (state) {
        case SCI_DEV_READY:
        case SCI_STP_DEV_IDLE:
        case SCI_STP_DEV_CMD:
        case SCI_STP_DEV_NCQ:
        case SCI_STP_DEV_NCQ_ERROR:
        case SCI_STP_DEV_AWAIT_RESET:
        case SCI_SMP_DEV_IDLE:
        case SCI_SMP_DEV_CMD:
                return true;
        default:
                return false;
        }
}

/*
 * called once the remote node context has transisitioned to a ready
 * state (after suspending RX and/or TX due to early D2H fis)
 */
static void atapi_remote_device_resume_done(void *_dev)
{
        struct isci_remote_device *idev = _dev;
        struct isci_request *ireq = idev->working_request;

        sci_change_state(&ireq->sm, SCI_REQ_COMPLETED);
}

enum sci_status sci_remote_device_event_handler(struct isci_remote_device *idev,
                                                     u32 event_code)
{
        enum sci_status status;
        struct sci_base_state_machine *sm = &idev->sm;
        enum sci_remote_device_states state = sm->current_state_id;

        switch (scu_get_event_type(event_code)) {
        case SCU_EVENT_TYPE_RNC_OPS_MISC:
        case SCU_EVENT_TYPE_RNC_SUSPEND_TX:
        case SCU_EVENT_TYPE_RNC_SUSPEND_TX_RX:
                status = sci_remote_node_context_event_handler(&idev->rnc, event_code);
                break;
        case SCU_EVENT_TYPE_PTX_SCHEDULE_EVENT:
                if (scu_get_event_code(event_code) == SCU_EVENT_IT_NEXUS_TIMEOUT) {
                        status = SCI_SUCCESS;

                        /* Suspend the associated RNC */
                        sci_remote_device_suspend(idev, SCI_SW_SUSPEND_NORMAL);

                        dev_dbg(scirdev_to_dev(idev),
                                "%s: device: %p event code: %x: %s\n",
                                __func__, idev, event_code,
                                is_remote_device_ready(idev)
                                ? "I_T_Nexus_Timeout event"
                                : "I_T_Nexus_Timeout event in wrong state");

                        break;
                }
                /* fall through - and treat as unhandled... */
        default:
                dev_dbg(scirdev_to_dev(idev),
                        "%s: device: %p event code: %x: %s\n",
                        __func__, idev, event_code,
                        is_remote_device_ready(idev)
                        ? "unexpected event"
                        : "unexpected event in wrong state");
                status = SCI_FAILURE_INVALID_STATE;
                break;
        }

        if (status != SCI_SUCCESS)
                return status;

        /* Decode device-specific states that may require an RNC resume during
         * normal operation.  When the abort path is active, these resumes are
         * managed when the abort path exits.
         */
        if (state == SCI_STP_DEV_ATAPI_ERROR) {
                /* For ATAPI error state resume the RNC right away. */
                if (scu_get_event_type(event_code) == SCU_EVENT_TYPE_RNC_SUSPEND_TX ||
                    scu_get_event_type(event_code) == SCU_EVENT_TYPE_RNC_SUSPEND_TX_RX) {
                        return sci_remote_node_context_resume(&idev->rnc,
                                                              atapi_remote_device_resume_done,
                                                              idev);
                }
        }

        if (state == SCI_STP_DEV_IDLE) {

                /* We pick up suspension events to handle specifically to this
                 * state. We resume the RNC right away.
                 */
                if (scu_get_event_type(event_code) == SCU_EVENT_TYPE_RNC_SUSPEND_TX ||
                    scu_get_event_type(event_code) == SCU_EVENT_TYPE_RNC_SUSPEND_TX_RX)
                        status = sci_remote_node_context_resume(&idev->rnc, NULL, NULL);
        }

        return status;
}

static void sci_remote_device_start_request(struct isci_remote_device *idev,
                                                 struct isci_request *ireq,
                                                 enum sci_status status)
{
        struct isci_port *iport = idev->owning_port;

        /* cleanup requests that failed after starting on the port */
        if (status != SCI_SUCCESS)
                sci_port_complete_io(iport, idev, ireq);
        else {
                kref_get(&idev->kref);
                idev->started_request_count++;
        }
}

enum sci_status sci_remote_device_start_io(struct isci_host *ihost,
                                                struct isci_remote_device *idev,
                                                struct isci_request *ireq)
{
        struct sci_base_state_machine *sm = &idev->sm;
        enum sci_remote_device_states state = sm->current_state_id;
        struct isci_port *iport = idev->owning_port;
        enum sci_status status;

        switch (state) {
        case SCI_DEV_INITIAL:
        case SCI_DEV_STOPPED:
        case SCI_DEV_STARTING:
        case SCI_STP_DEV_NCQ_ERROR:
        case SCI_DEV_STOPPING:
        case SCI_DEV_FAILED:
        case SCI_DEV_RESETTING:
        case SCI_DEV_FINAL:
        default:
                dev_warn(scirdev_to_dev(idev), "%s: in wrong state: %s\n",
                         __func__, dev_state_name(state));
                return SCI_FAILURE_INVALID_STATE;
        case SCI_DEV_READY:
                /* attempt to start an io request for this device object. The remote
                 * device object will issue the start request for the io and if
                 * successful it will start the request for the port object then
                 * increment its own request count.
                 */
                status = sci_port_start_io(iport, idev, ireq);
                if (status != SCI_SUCCESS)
                        return status;

                status = sci_remote_node_context_start_io(&idev->rnc, ireq);
                if (status != SCI_SUCCESS)
                        break;

                status = sci_request_start(ireq);
                break;
        case SCI_STP_DEV_IDLE: {
                /* handle the start io operation for a sata device that is in
                 * the command idle state. - Evalute the type of IO request to
                 * be started - If its an NCQ request change to NCQ substate -
                 * If its any other command change to the CMD substate
                 *
                 * If this is a softreset we may want to have a different
                 * substate.
                 */
                enum sci_remote_device_states new_state;
                struct sas_task *task = isci_request_access_task(ireq);

                status = sci_port_start_io(iport, idev, ireq);
                if (status != SCI_SUCCESS)
                        return status;

                status = sci_remote_node_context_start_io(&idev->rnc, ireq);
                if (status != SCI_SUCCESS)
                        break;

                status = sci_request_start(ireq);
                if (status != SCI_SUCCESS)
                        break;

                if (task->ata_task.use_ncq)
                        new_state = SCI_STP_DEV_NCQ;
                else {
                        idev->working_request = ireq;
                        new_state = SCI_STP_DEV_CMD;
                }
                sci_change_state(sm, new_state);
                break;
        }
        case SCI_STP_DEV_NCQ: {
                struct sas_task *task = isci_request_access_task(ireq);

                if (task->ata_task.use_ncq) {
                        status = sci_port_start_io(iport, idev, ireq);
                        if (status != SCI_SUCCESS)
                                return status;

                        status = sci_remote_node_context_start_io(&idev->rnc, ireq);
                        if (status != SCI_SUCCESS)
                                break;

                        status = sci_request_start(ireq);
                } else
                        return SCI_FAILURE_INVALID_STATE;
                break;
        }
        case SCI_STP_DEV_AWAIT_RESET:
                return SCI_FAILURE_REMOTE_DEVICE_RESET_REQUIRED;
        case SCI_SMP_DEV_IDLE:
                status = sci_port_start_io(iport, idev, ireq);
                if (status != SCI_SUCCESS)
                        return status;

                status = sci_remote_node_context_start_io(&idev->rnc, ireq);
                if (status != SCI_SUCCESS)
                        break;

                status = sci_request_start(ireq);
                if (status != SCI_SUCCESS)
                        break;

                idev->working_request = ireq;
                sci_change_state(&idev->sm, SCI_SMP_DEV_CMD);
                break;
        case SCI_STP_DEV_CMD:
        case SCI_SMP_DEV_CMD:
                /* device is already handling a command it can not accept new commands
                 * until this one is complete.
                 */
                return SCI_FAILURE_INVALID_STATE;
        }

        sci_remote_device_start_request(idev, ireq, status);
        return status;
}

static enum sci_status common_complete_io(struct isci_port *iport,
                                          struct isci_remote_device *idev,
                                          struct isci_request *ireq)
{
        enum sci_status status;

        status = sci_request_complete(ireq);
        if (status != SCI_SUCCESS)
                return status;

        status = sci_port_complete_io(iport, idev, ireq);
        if (status != SCI_SUCCESS)
                return status;

        sci_remote_device_decrement_request_count(idev);
        return status;
}

enum sci_status sci_remote_device_complete_io(struct isci_host *ihost,
                                                   struct isci_remote_device *idev,
                                                   struct isci_request *ireq)
{
        struct sci_base_state_machine *sm = &idev->sm;
        enum sci_remote_device_states state = sm->current_state_id;
        struct isci_port *iport = idev->owning_port;
        enum sci_status status;

        switch (state) {
        case SCI_DEV_INITIAL:
        case SCI_DEV_STOPPED:
        case SCI_DEV_STARTING:
        case SCI_STP_DEV_IDLE:
        case SCI_SMP_DEV_IDLE:
        case SCI_DEV_FAILED:
        case SCI_DEV_FINAL:
        default:
                dev_warn(scirdev_to_dev(idev), "%s: in wrong state: %s\n",
                         __func__, dev_state_name(state));
                return SCI_FAILURE_INVALID_STATE;
        case SCI_DEV_READY:
        case SCI_STP_DEV_AWAIT_RESET:
        case SCI_DEV_RESETTING:
                status = common_complete_io(iport, idev, ireq);
                break;
        case SCI_STP_DEV_CMD:
        case SCI_STP_DEV_NCQ:
        case SCI_STP_DEV_NCQ_ERROR:
        case SCI_STP_DEV_ATAPI_ERROR:
                status = common_complete_io(iport, idev, ireq);
                if (status != SCI_SUCCESS)
                        break;

                if (ireq->sci_status == SCI_FAILURE_REMOTE_DEVICE_RESET_REQUIRED) {
                        /* This request causes hardware error, device needs to be Lun Reset.
                         * So here we force the state machine to IDLE state so the rest IOs
                         * can reach RNC state handler, these IOs will be completed by RNC with
                         * status of "DEVICE_RESET_REQUIRED", instead of "INVALID STATE".
                         */
                        sci_change_state(sm, SCI_STP_DEV_AWAIT_RESET);
                } else if (idev->started_request_count == 0)
                        sci_change_state(sm, SCI_STP_DEV_IDLE);
                break;
        case SCI_SMP_DEV_CMD:
                status = common_complete_io(iport, idev, ireq);
                if (status != SCI_SUCCESS)
                        break;
                sci_change_state(sm, SCI_SMP_DEV_IDLE);
                break;
        case SCI_DEV_STOPPING:
                status = common_complete_io(iport, idev, ireq);
                if (status != SCI_SUCCESS)
                        break;

                if (idev->started_request_count == 0)
                        sci_remote_node_context_destruct(&idev->rnc,
                                                         rnc_destruct_done,
                                                         idev);
                break;
        }

        if (status != SCI_SUCCESS)
                dev_err(scirdev_to_dev(idev),
                        "%s: Port:0x%p Device:0x%p Request:0x%p Status:0x%x "
                        "could not complete\n", __func__, iport,
                        idev, ireq, status);
        else
                isci_put_device(idev);

        return status;
}

static void sci_remote_device_continue_request(void *dev)
{
        struct isci_remote_device *idev = dev;

        /* we need to check if this request is still valid to continue. */
        if (idev->working_request)
                sci_controller_continue_io(idev->working_request);
}

enum sci_status sci_remote_device_start_task(struct isci_host *ihost,
                                                  struct isci_remote_device *idev,
                                                  struct isci_request *ireq)
{
        struct sci_base_state_machine *sm = &idev->sm;
        enum sci_remote_device_states state = sm->current_state_id;
        struct isci_port *iport = idev->owning_port;
        enum sci_status status;

        switch (state) {
        case SCI_DEV_INITIAL:
        case SCI_DEV_STOPPED:
        case SCI_DEV_STARTING:
        case SCI_SMP_DEV_IDLE:
        case SCI_SMP_DEV_CMD:
        case SCI_DEV_STOPPING:
        case SCI_DEV_FAILED:
        case SCI_DEV_RESETTING:
        case SCI_DEV_FINAL:
        default:
                dev_warn(scirdev_to_dev(idev), "%s: in wrong state: %s\n",
                         __func__, dev_state_name(state));
                return SCI_FAILURE_INVALID_STATE;
        case SCI_STP_DEV_IDLE:
        case SCI_STP_DEV_CMD:
        case SCI_STP_DEV_NCQ:
        case SCI_STP_DEV_NCQ_ERROR:
        case SCI_STP_DEV_AWAIT_RESET:
                status = sci_port_start_io(iport, idev, ireq);
                if (status != SCI_SUCCESS)
                        return status;

                status = sci_request_start(ireq);
                if (status != SCI_SUCCESS)
                        goto out;

                /* Note: If the remote device state is not IDLE this will
                 * replace the request that probably resulted in the task
                 * management request.
                 */
                idev->working_request = ireq;
                sci_change_state(sm, SCI_STP_DEV_CMD);

                /* The remote node context must cleanup the TCi to NCQ mapping
                 * table.  The only way to do this correctly is to either write
                 * to the TLCR register or to invalidate and repost the RNC. In
                 * either case the remote node context state machine will take
                 * the correct action when the remote node context is suspended
                 * and later resumed.
                 */
                sci_remote_device_suspend(idev,
                                          SCI_SW_SUSPEND_LINKHANG_DETECT);

                status = sci_remote_node_context_start_task(&idev->rnc, ireq,
                                sci_remote_device_continue_request, idev);

        out:
                sci_remote_device_start_request(idev, ireq, status);
                /* We need to let the controller start request handler know that
                 * it can't post TC yet. We will provide a callback function to
                 * post TC when RNC gets resumed.
                 */
                return SCI_FAILURE_RESET_DEVICE_PARTIAL_SUCCESS;
        case SCI_DEV_READY:
                status = sci_port_start_io(iport, idev, ireq);
                if (status != SCI_SUCCESS)
                        return status;

                /* Resume the RNC as needed: */
                status = sci_remote_node_context_start_task(&idev->rnc, ireq,
                                                            NULL, NULL);
                if (status != SCI_SUCCESS)
                        break;

                status = sci_request_start(ireq);
                break;
        }
        sci_remote_device_start_request(idev, ireq, status);

        return status;
}

void sci_remote_device_post_request(struct isci_remote_device *idev, u32 request)
{
        struct isci_port *iport = idev->owning_port;
        u32 context;

        context = request |
                  (ISCI_PEG << SCU_CONTEXT_COMMAND_PROTOCOL_ENGINE_GROUP_SHIFT) |
                  (iport->physical_port_index << SCU_CONTEXT_COMMAND_LOGICAL_PORT_SHIFT) |
                  idev->rnc.remote_node_index;

        sci_controller_post_request(iport->owning_controller, context);
}

/* called once the remote node context has transisitioned to a
 * ready state.  This is the indication that the remote device object can also
 * transition to ready.
 */
static void remote_device_resume_done(void *_dev)
{
        struct isci_remote_device *idev = _dev;

        if (is_remote_device_ready(idev))
                return;

        /* go 'ready' if we are not already in a ready state */
        sci_change_state(&idev->sm, SCI_DEV_READY);
}

static void sci_stp_remote_device_ready_idle_substate_resume_complete_handler(void *_dev)
{
        struct isci_remote_device *idev = _dev;
        struct isci_host *ihost = idev->owning_port->owning_controller;

        /* For NCQ operation we do not issue a isci_remote_device_not_ready().
         * As a result, avoid sending the ready notification.
         */
        if (idev->sm.previous_state_id != SCI_STP_DEV_NCQ)
                isci_remote_device_ready(ihost, idev);
}

static void sci_remote_device_initial_state_enter(struct sci_base_state_machine *sm)
{
        struct isci_remote_device *idev = container_of(sm, typeof(*idev), sm);

        /* Initial state is a transitional state to the stopped state */
        sci_change_state(&idev->sm, SCI_DEV_STOPPED);
}

/**
 * sci_remote_device_destruct() - free remote node context and destruct
 * @remote_device: This parameter specifies the remote device to be destructed.
 *
 * Remote device objects are a limited resource.  As such, they must be
 * protected.  Thus calls to construct and destruct are mutually exclusive and
 * non-reentrant. The return value shall indicate if the device was
 * successfully destructed or if some failure occurred. enum sci_status This value
 * is returned if the device is successfully destructed.
 * SCI_FAILURE_INVALID_REMOTE_DEVICE This value is returned if the supplied
 * device isn't valid (e.g. it's already been destoryed, the handle isn't
 * valid, etc.).
 */
static enum sci_status sci_remote_device_destruct(struct isci_remote_device *idev)
{
        struct sci_base_state_machine *sm = &idev->sm;
        enum sci_remote_device_states state = sm->current_state_id;
        struct isci_host *ihost;

        if (state != SCI_DEV_STOPPED) {
                dev_warn(scirdev_to_dev(idev), "%s: in wrong state: %s\n",
                         __func__, dev_state_name(state));
                return SCI_FAILURE_INVALID_STATE;
        }

        ihost = idev->owning_port->owning_controller;
        sci_controller_free_remote_node_context(ihost, idev,
                                                     idev->rnc.remote_node_index);
        idev->rnc.remote_node_index = SCIC_SDS_REMOTE_NODE_CONTEXT_INVALID_INDEX;
        sci_change_state(sm, SCI_DEV_FINAL);

        return SCI_SUCCESS;
}

/**
 * isci_remote_device_deconstruct() - This function frees an isci_remote_device.
 * @ihost: This parameter specifies the isci host object.
 * @idev: This parameter specifies the remote device to be freed.
 *
 */
static void isci_remote_device_deconstruct(struct isci_host *ihost, struct isci_remote_device *idev)
{
        dev_dbg(&ihost->pdev->dev,
                "%s: isci_device = %p\n", __func__, idev);

        /* There should not be any outstanding io's. All paths to
         * here should go through isci_remote_device_nuke_requests.
         * If we hit this condition, we will need a way to complete
         * io requests in process */
        BUG_ON(idev->started_request_count > 0);

        sci_remote_device_destruct(idev);
        list_del_init(&idev->node);
        isci_put_device(idev);
}

static void sci_remote_device_stopped_state_enter(struct sci_base_state_machine *sm)
{
        struct isci_remote_device *idev = container_of(sm, typeof(*idev), sm);
        struct isci_host *ihost = idev->owning_port->owning_controller;
        u32 prev_state;

        /* If we are entering from the stopping state let the SCI User know that
         * the stop operation has completed.
         */
        prev_state = idev->sm.previous_state_id;
        if (prev_state == SCI_DEV_STOPPING)
                isci_remote_device_deconstruct(ihost, idev);

        sci_controller_remote_device_stopped(ihost, idev);
}

static void sci_remote_device_starting_state_enter(struct sci_base_state_machine *sm)
{
        struct isci_remote_device *idev = container_of(sm, typeof(*idev), sm);
        struct isci_host *ihost = idev->owning_port->owning_controller;

        isci_remote_device_not_ready(ihost, idev,
                                     SCIC_REMOTE_DEVICE_NOT_READY_START_REQUESTED);
}

static void sci_remote_device_ready_state_enter(struct sci_base_state_machine *sm)
{
        struct isci_remote_device *idev = container_of(sm, typeof(*idev), sm);
        struct isci_host *ihost = idev->owning_port->owning_controller;
        struct domain_device *dev = idev->domain_dev;

        if (dev->dev_type == SAS_SATA_DEV || (dev->tproto & SAS_PROTOCOL_SATA)) {
                sci_change_state(&idev->sm, SCI_STP_DEV_IDLE);
        } else if (dev_is_expander(dev)) {
                sci_change_state(&idev->sm, SCI_SMP_DEV_IDLE);
        } else
                isci_remote_device_ready(ihost, idev);
}

static void sci_remote_device_ready_state_exit(struct sci_base_state_machine *sm)
{
        struct isci_remote_device *idev = container_of(sm, typeof(*idev), sm);
        struct domain_device *dev = idev->domain_dev;

        if (dev->dev_type == SAS_END_DEVICE) {
                struct isci_host *ihost = idev->owning_port->owning_controller;

                isci_remote_device_not_ready(ihost, idev,
                                             SCIC_REMOTE_DEVICE_NOT_READY_STOP_REQUESTED);
        }
}

static void sci_remote_device_resetting_state_enter(struct sci_base_state_machine *sm)
{
        struct isci_remote_device *idev = container_of(sm, typeof(*idev), sm);
        struct isci_host *ihost = idev->owning_port->owning_controller;

        dev_dbg(&ihost->pdev->dev,
                "%s: isci_device = %p\n", __func__, idev);

        sci_remote_device_suspend(idev, SCI_SW_SUSPEND_LINKHANG_DETECT);
}

static void sci_remote_device_resetting_state_exit(struct sci_base_state_machine *sm)
{
        struct isci_remote_device *idev = container_of(sm, typeof(*idev), sm);
        struct isci_host *ihost = idev->owning_port->owning_controller;

        dev_dbg(&ihost->pdev->dev,
                "%s: isci_device = %p\n", __func__, idev);

        sci_remote_node_context_resume(&idev->rnc, NULL, NULL);
}

static void sci_stp_remote_device_ready_idle_substate_enter(struct sci_base_state_machine *sm)
{
        struct isci_remote_device *idev = container_of(sm, typeof(*idev), sm);

        idev->working_request = NULL;
        if (sci_remote_node_context_is_ready(&idev->rnc)) {
                /*
                 * Since the RNC is ready, it's alright to finish completion
                 * processing (e.g. signal the remote device is ready). */
                sci_stp_remote_device_ready_idle_substate_resume_complete_handler(idev);
        } else {
                sci_remote_node_context_resume(&idev->rnc,
                        sci_stp_remote_device_ready_idle_substate_resume_complete_handler,
                        idev);
        }
}

static void sci_stp_remote_device_ready_cmd_substate_enter(struct sci_base_state_machine *sm)
{
        struct isci_remote_device *idev = container_of(sm, typeof(*idev), sm);
        struct isci_host *ihost = idev->owning_port->owning_controller;

        BUG_ON(idev->working_request == NULL);

        isci_remote_device_not_ready(ihost, idev,
                                     SCIC_REMOTE_DEVICE_NOT_READY_SATA_REQUEST_STARTED);
}

static void sci_stp_remote_device_ready_ncq_error_substate_enter(struct sci_base_state_machine *sm)
{
        struct isci_remote_device *idev = container_of(sm, typeof(*idev), sm);
        struct isci_host *ihost = idev->owning_port->owning_controller;

        if (idev->not_ready_reason == SCIC_REMOTE_DEVICE_NOT_READY_SATA_SDB_ERROR_FIS_RECEIVED)
                isci_remote_device_not_ready(ihost, idev,
                                             idev->not_ready_reason);
}

static void sci_smp_remote_device_ready_idle_substate_enter(struct sci_base_state_machine *sm)
{
        struct isci_remote_device *idev = container_of(sm, typeof(*idev), sm);
        struct isci_host *ihost = idev->owning_port->owning_controller;

        isci_remote_device_ready(ihost, idev);
}

static void sci_smp_remote_device_ready_cmd_substate_enter(struct sci_base_state_machine *sm)
{
        struct isci_remote_device *idev = container_of(sm, typeof(*idev), sm);
        struct isci_host *ihost = idev->owning_port->owning_controller;

        BUG_ON(idev->working_request == NULL);

        isci_remote_device_not_ready(ihost, idev,
                                     SCIC_REMOTE_DEVICE_NOT_READY_SMP_REQUEST_STARTED);
}

static void sci_smp_remote_device_ready_cmd_substate_exit(struct sci_base_state_machine *sm)
{
        struct isci_remote_device *idev = container_of(sm, typeof(*idev), sm);

        idev->working_request = NULL;
}

static const struct sci_base_state sci_remote_device_state_table[] = {
        [SCI_DEV_INITIAL] = {
                .enter_state = sci_remote_device_initial_state_enter,
        },
        [SCI_DEV_STOPPED] = {
                .enter_state = sci_remote_device_stopped_state_enter,
        },
        [SCI_DEV_STARTING] = {
                .enter_state = sci_remote_device_starting_state_enter,
        },
        [SCI_DEV_READY] = {
                .enter_state = sci_remote_device_ready_state_enter,
                .exit_state  = sci_remote_device_ready_state_exit
        },
        [SCI_STP_DEV_IDLE] = {
                .enter_state = sci_stp_remote_device_ready_idle_substate_enter,
        },
        [SCI_STP_DEV_CMD] = {
                .enter_state = sci_stp_remote_device_ready_cmd_substate_enter,
        },
        [SCI_STP_DEV_NCQ] = { },
        [SCI_STP_DEV_NCQ_ERROR] = {
                .enter_state = sci_stp_remote_device_ready_ncq_error_substate_enter,
        },
        [SCI_STP_DEV_ATAPI_ERROR] = { },
        [SCI_STP_DEV_AWAIT_RESET] = { },
        [SCI_SMP_DEV_IDLE] = {
                .enter_state = sci_smp_remote_device_ready_idle_substate_enter,
        },
        [SCI_SMP_DEV_CMD] = {
                .enter_state = sci_smp_remote_device_ready_cmd_substate_enter,
                .exit_state  = sci_smp_remote_device_ready_cmd_substate_exit,
        },
        [SCI_DEV_STOPPING] = { },
        [SCI_DEV_FAILED] = { },
        [SCI_DEV_RESETTING] = {
                .enter_state = sci_remote_device_resetting_state_enter,
                .exit_state  = sci_remote_device_resetting_state_exit
        },
        [SCI_DEV_FINAL] = { },
};

/**
 * sci_remote_device_construct() - common construction
 * @sci_port: SAS/SATA port through which this device is accessed.
 * @sci_dev: remote device to construct
 *
 * This routine just performs benign initialization and does not
 * allocate the remote_node_context which is left to
 * sci_remote_device_[de]a_construct().  sci_remote_device_destruct()
 * frees the remote_node_context(s) for the device.
 */
static void sci_remote_device_construct(struct isci_port *iport,
                                  struct isci_remote_device *idev)
{
        idev->owning_port = iport;
        idev->started_request_count = 0;

        sci_init_sm(&idev->sm, sci_remote_device_state_table, SCI_DEV_INITIAL);

        sci_remote_node_context_construct(&idev->rnc,
                                               SCIC_SDS_REMOTE_NODE_CONTEXT_INVALID_INDEX);
}

/**
 * sci_remote_device_da_construct() - construct direct attached device.
 *
 * The information (e.g. IAF, Signature FIS, etc.) necessary to build
 * the device is known to the SCI Core since it is contained in the
 * sci_phy object.  Remote node context(s) is/are a global resource
 * allocated by this routine, freed by sci_remote_device_destruct().
 *
 * Returns:
 * SCI_FAILURE_DEVICE_EXISTS - device has already been constructed.
 * SCI_FAILURE_UNSUPPORTED_PROTOCOL - e.g. sas device attached to
 * sata-only controller instance.
 * SCI_FAILURE_INSUFFICIENT_RESOURCES - remote node contexts exhausted.
 */
static enum sci_status sci_remote_device_da_construct(struct isci_port *iport,
                                                       struct isci_remote_device *idev)
{
        enum sci_status status;
        struct sci_port_properties properties;

        sci_remote_device_construct(iport, idev);

        sci_port_get_properties(iport, &properties);
        /* Get accurate port width from port's phy mask for a DA device. */
        idev->device_port_width = hweight32(properties.phy_mask);

        status = sci_controller_allocate_remote_node_context(iport->owning_controller,
                                                             idev,
                                                             &idev->rnc.remote_node_index);

        if (status != SCI_SUCCESS)
                return status;

        idev->connection_rate = sci_port_get_max_allowed_speed(iport);

        return SCI_SUCCESS;
}

/**
 * sci_remote_device_ea_construct() - construct expander attached device
 *
 * Remote node context(s) is/are a global resource allocated by this
 * routine, freed by sci_remote_device_destruct().
 *
 * Returns:
 * SCI_FAILURE_DEVICE_EXISTS - device has already been constructed.
 * SCI_FAILURE_UNSUPPORTED_PROTOCOL - e.g. sas device attached to
 * sata-only controller instance.
 * SCI_FAILURE_INSUFFICIENT_RESOURCES - remote node contexts exhausted.
 */
static enum sci_status sci_remote_device_ea_construct(struct isci_port *iport,
                                                       struct isci_remote_device *idev)
{
        struct domain_device *dev = idev->domain_dev;
        enum sci_status status;

        sci_remote_device_construct(iport, idev);

        status = sci_controller_allocate_remote_node_context(iport->owning_controller,
                                                                  idev,
                                                                  &idev->rnc.remote_node_index);
        if (status != SCI_SUCCESS)
                return status;

        /* For SAS-2 the physical link rate is actually a logical link
         * rate that incorporates multiplexing.  The SCU doesn't
         * incorporate multiplexing and for the purposes of the
         * connection the logical link rate is that same as the
         * physical.  Furthermore, the SAS-2 and SAS-1.1 fields overlay
         * one another, so this code works for both situations.
         */
        idev->connection_rate = min_t(u16, sci_port_get_max_allowed_speed(iport),
                                         dev->linkrate);

        /* / @todo Should I assign the port width by reading all of the phys on the port? */
        idev->device_port_width = 1;

        return SCI_SUCCESS;
}

enum sci_status sci_remote_device_resume(
        struct isci_remote_device *idev,
        scics_sds_remote_node_context_callback cb_fn,
        void *cb_p)
{
        enum sci_status status;

        status = sci_remote_node_context_resume(&idev->rnc, cb_fn, cb_p);
        if (status != SCI_SUCCESS)
                dev_dbg(scirdev_to_dev(idev), "%s: failed to resume: %d\n",
                        __func__, status);
        return status;
}

static void isci_remote_device_resume_from_abort_complete(void *cbparam)
{
        struct isci_remote_device *idev = cbparam;
        struct isci_host *ihost = idev->owning_port->owning_controller;
        scics_sds_remote_node_context_callback abort_resume_cb =
                idev->abort_resume_cb;

        dev_dbg(scirdev_to_dev(idev), "%s: passing-along resume: %p\n",
                __func__, abort_resume_cb);

        if (abort_resume_cb != NULL) {
                idev->abort_resume_cb = NULL;
                abort_resume_cb(idev->abort_resume_cbparam);
        }
        clear_bit(IDEV_ABORT_PATH_RESUME_PENDING, &idev->flags);
        wake_up(&ihost->eventq);
}

static bool isci_remote_device_test_resume_done(
        struct isci_host *ihost,
        struct isci_remote_device *idev)
{
        unsigned long flags;
        bool done;

        spin_lock_irqsave(&ihost->scic_lock, flags);
        done = !test_bit(IDEV_ABORT_PATH_RESUME_PENDING, &idev->flags)
                || test_bit(IDEV_STOP_PENDING, &idev->flags)
                || sci_remote_node_context_is_being_destroyed(&idev->rnc);
        spin_unlock_irqrestore(&ihost->scic_lock, flags);

        return done;
}

void isci_remote_device_wait_for_resume_from_abort(
        struct isci_host *ihost,
        struct isci_remote_device *idev)
{
        dev_dbg(&ihost->pdev->dev, "%s: starting resume wait: %p\n",
                 __func__, idev);

        #define MAX_RESUME_MSECS 10000
        if (!wait_event_timeout(ihost->eventq,
                                isci_remote_device_test_resume_done(ihost, idev),
                                msecs_to_jiffies(MAX_RESUME_MSECS))) {

                dev_warn(&ihost->pdev->dev, "%s: #### Timeout waiting for "
                         "resume: %p\n", __func__, idev);
        }
        clear_bit(IDEV_ABORT_PATH_RESUME_PENDING, &idev->flags);

        dev_dbg(&ihost->pdev->dev, "%s: resume wait done: %p\n",
                 __func__, idev);
}

enum sci_status isci_remote_device_resume_from_abort(
        struct isci_host *ihost,
        struct isci_remote_device *idev)
{
        unsigned long flags;
        enum sci_status status = SCI_SUCCESS;
        int destroyed;

        spin_lock_irqsave(&ihost->scic_lock, flags);
        /* Preserve any current resume callbacks, for instance from other
         * resumptions.
         */
        idev->abort_resume_cb = idev->rnc.user_callback;
        idev->abort_resume_cbparam = idev->rnc.user_cookie;
        set_bit(IDEV_ABORT_PATH_RESUME_PENDING, &idev->flags);
        clear_bit(IDEV_ABORT_PATH_ACTIVE, &idev->flags);
        destroyed = sci_remote_node_context_is_being_destroyed(&idev->rnc);
        if (!destroyed)
                status = sci_remote_device_resume(
                        idev, isci_remote_device_resume_from_abort_complete,
                        idev);
        spin_unlock_irqrestore(&ihost->scic_lock, flags);
        if (!destroyed && (status == SCI_SUCCESS))
                isci_remote_device_wait_for_resume_from_abort(ihost, idev);
        else
                clear_bit(IDEV_ABORT_PATH_RESUME_PENDING, &idev->flags);

        return status;
}

/**
 * sci_remote_device_start() - This method will start the supplied remote
 *    device.  This method enables normal IO requests to flow through to the
 *    remote device.
 * @remote_device: This parameter specifies the device to be started.
 * @timeout: This parameter specifies the number of milliseconds in which the
 *    start operation should complete.
 *
 * An indication of whether the device was successfully started. SCI_SUCCESS
 * This value is returned if the device was successfully started.
 * SCI_FAILURE_INVALID_PHY This value is returned if the user attempts to start
 * the device when there have been no phys added to it.
 */
static enum sci_status sci_remote_device_start(struct isci_remote_device *idev,
                                               u32 timeout)
{
        struct sci_base_state_machine *sm = &idev->sm;
        enum sci_remote_device_states state = sm->current_state_id;
        enum sci_status status;

        if (state != SCI_DEV_STOPPED) {
                dev_warn(scirdev_to_dev(idev), "%s: in wrong state: %s\n",
                         __func__, dev_state_name(state));
                return SCI_FAILURE_INVALID_STATE;
        }

        status = sci_remote_device_resume(idev, remote_device_resume_done,
                                          idev);
        if (status != SCI_SUCCESS)
                return status;

        sci_change_state(sm, SCI_DEV_STARTING);

        return SCI_SUCCESS;
}

static enum sci_status isci_remote_device_construct(struct isci_port *iport,
                                                    struct isci_remote_device *idev)
{
        struct isci_host *ihost = iport->isci_host;
        struct domain_device *dev = idev->domain_dev;
        enum sci_status status;

        if (dev->parent && dev_is_expander(dev->parent))
                status = sci_remote_device_ea_construct(iport, idev);
        else
                status = sci_remote_device_da_construct(iport, idev);

        if (status != SCI_SUCCESS) {
                dev_dbg(&ihost->pdev->dev, "%s: construct failed: %d\n",
                        __func__, status);

                return status;
        }

        /* start the device. */
        status = sci_remote_device_start(idev, ISCI_REMOTE_DEVICE_START_TIMEOUT);

        if (status != SCI_SUCCESS)
                dev_warn(&ihost->pdev->dev, "remote device start failed: %d\n",
                         status);

        return status;
}

/**
 * This function builds the isci_remote_device when a libsas dev_found message
 *    is received.
 * @isci_host: This parameter specifies the isci host object.
 * @port: This parameter specifies the isci_port conected to this device.
 *
 * pointer to new isci_remote_device.
 */
static struct isci_remote_device *
isci_remote_device_alloc(struct isci_host *ihost, struct isci_port *iport)
{
        struct isci_remote_device *idev;
        int i;

        for (i = 0; i < SCI_MAX_REMOTE_DEVICES; i++) {
                idev = &ihost->devices[i];
                if (!test_and_set_bit(IDEV_ALLOCATED, &idev->flags))
                        break;
        }

        if (i >= SCI_MAX_REMOTE_DEVICES) {
                dev_warn(&ihost->pdev->dev, "%s: failed\n", __func__);
                return NULL;
        }
        if (WARN_ONCE(!list_empty(&idev->node), "found non-idle remote device\n"))
                return NULL;

        return idev;
}

void isci_remote_device_release(struct kref *kref)
{
        struct isci_remote_device *idev = container_of(kref, typeof(*idev), kref);
        struct isci_host *ihost = idev->isci_port->isci_host;

        idev->domain_dev = NULL;
        idev->isci_port = NULL;
        clear_bit(IDEV_START_PENDING, &idev->flags);
        clear_bit(IDEV_STOP_PENDING, &idev->flags);
        clear_bit(IDEV_IO_READY, &idev->flags);
        clear_bit(IDEV_GONE, &idev->flags);
        smp_mb__before_atomic();
        clear_bit(IDEV_ALLOCATED, &idev->flags);
        wake_up(&ihost->eventq);
}

/**
 * isci_remote_device_stop() - This function is called internally to stop the
 *    remote device.
 * @isci_host: This parameter specifies the isci host object.
 * @isci_device: This parameter specifies the remote device.
 *
 * The status of the ihost request to stop.
 */
enum sci_status isci_remote_device_stop(struct isci_host *ihost, struct isci_remote_device *idev)
{
        enum sci_status status;
        unsigned long flags;

        dev_dbg(&ihost->pdev->dev,
                "%s: isci_device = %p\n", __func__, idev);

        spin_lock_irqsave(&ihost->scic_lock, flags);
        idev->domain_dev->lldd_dev = NULL; /* disable new lookups */
        set_bit(IDEV_GONE, &idev->flags);

        set_bit(IDEV_STOP_PENDING, &idev->flags);
        status = sci_remote_device_stop(idev, 50);
        spin_unlock_irqrestore(&ihost->scic_lock, flags);

        /* Wait for the stop complete callback. */
        if (WARN_ONCE(status != SCI_SUCCESS, "failed to stop device\n"))
                /* nothing to wait for */;
        else
                wait_for_device_stop(ihost, idev);

        dev_dbg(&ihost->pdev->dev,
                "%s: isci_device = %p, waiting done.\n", __func__, idev);

        return status;
}

/**
 * isci_remote_device_gone() - This function is called by libsas when a domain
 *    device is removed.
 * @domain_device: This parameter specifies the libsas domain device.
 *
 */
void isci_remote_device_gone(struct domain_device *dev)
{
        struct isci_host *ihost = dev_to_ihost(dev);
        struct isci_remote_device *idev = dev->lldd_dev;

        dev_dbg(&ihost->pdev->dev,
                "%s: domain_device = %p, isci_device = %p, isci_port = %p\n",
                __func__, dev, idev, idev->isci_port);

        isci_remote_device_stop(ihost, idev);
}


/**
 * isci_remote_device_found() - This function is called by libsas when a remote
 *    device is discovered. A remote device object is created and started. the
 *    function then sleeps until the sci core device started message is
 *    received.
 * @domain_device: This parameter specifies the libsas domain device.
 *
 * status, zero indicates success.
 */
int isci_remote_device_found(struct domain_device *dev)
{
        struct isci_host *isci_host = dev_to_ihost(dev);
        struct isci_port *isci_port = dev->port->lldd_port;
        struct isci_remote_device *isci_device;
        enum sci_status status;

        dev_dbg(&isci_host->pdev->dev,
                "%s: domain_device = %p\n", __func__, dev);

        if (!isci_port)
                return -ENODEV;

        isci_device = isci_remote_device_alloc(isci_host, isci_port);
        if (!isci_device)
                return -ENODEV;

        kref_init(&isci_device->kref);
        INIT_LIST_HEAD(&isci_device->node);

        spin_lock_irq(&isci_host->scic_lock);
        isci_device->domain_dev = dev;
        isci_device->isci_port = isci_port;
        list_add_tail(&isci_device->node, &isci_port->remote_dev_list);

        set_bit(IDEV_START_PENDING, &isci_device->flags);
        status = isci_remote_device_construct(isci_port, isci_device);

        dev_dbg(&isci_host->pdev->dev,
                "%s: isci_device = %p\n",
                __func__, isci_device);

        if (status == SCI_SUCCESS) {
                /* device came up, advertise it to the world */
                dev->lldd_dev = isci_device;
        } else
                isci_put_device(isci_device);
        spin_unlock_irq(&isci_host->scic_lock);

        /* wait for the device ready callback. */
        wait_for_device_start(isci_host, isci_device);

        return status == SCI_SUCCESS ? 0 : -ENODEV;
}

enum sci_status isci_remote_device_suspend_terminate(
        struct isci_host *ihost,
        struct isci_remote_device *idev,
        struct isci_request *ireq)
{
        unsigned long flags;
        enum sci_status status;

        /* Put the device into suspension. */
        spin_lock_irqsave(&ihost->scic_lock, flags);
        set_bit(IDEV_ABORT_PATH_ACTIVE, &idev->flags);
        sci_remote_device_suspend(idev, SCI_SW_SUSPEND_LINKHANG_DETECT);
        spin_unlock_irqrestore(&ihost->scic_lock, flags);

        /* Terminate and wait for the completions. */
        status = isci_remote_device_terminate_requests(ihost, idev, ireq);
        if (status != SCI_SUCCESS)
                dev_dbg(&ihost->pdev->dev,
                        "%s: isci_remote_device_terminate_requests(%p) "
                                "returned %d!\n",
                        __func__, idev, status);

        /* NOTE: RNC resumption is left to the caller! */
        return status;
}

int isci_remote_device_is_safe_to_abort(
        struct isci_remote_device *idev)
{
        return sci_remote_node_context_is_safe_to_abort(&idev->rnc);
}

enum sci_status sci_remote_device_abort_requests_pending_abort(
        struct isci_remote_device *idev)
{
        return sci_remote_device_terminate_reqs_checkabort(idev, 1);
}

enum sci_status isci_remote_device_reset_complete(
        struct isci_host *ihost,
        struct isci_remote_device *idev)
{
        unsigned long flags;
        enum sci_status status;

        spin_lock_irqsave(&ihost->scic_lock, flags);
        status = sci_remote_device_reset_complete(idev);
        spin_unlock_irqrestore(&ihost->scic_lock, flags);

        return status;
}

void isci_dev_set_hang_detection_timeout(
        struct isci_remote_device *idev,
        u32 timeout)
{
        if (dev_is_sata(idev->domain_dev)) {
                if (timeout) {
                        if (test_and_set_bit(IDEV_RNC_LLHANG_ENABLED,
                                             &idev->flags))
                                return;  /* Already enabled. */
                } else if (!test_and_clear_bit(IDEV_RNC_LLHANG_ENABLED,
                                               &idev->flags))
                        return;  /* Not enabled. */

                sci_port_set_hang_detection_timeout(idev->owning_port,
                                                    timeout);
        }
}