Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

[mirror_ubuntu-artful-kernel.git] / drivers / scsi / ibmvscsi_tgt / ibmvscsi_tgt.c

/*******************************************************************************
 * IBM Virtual SCSI Target Driver
 * Copyright (C) 2003-2005 Dave Boutcher (boutcher@us.ibm.com) IBM Corp.
 *                         Santiago Leon (santil@us.ibm.com) IBM Corp.
 *                         Linda Xie (lxie@us.ibm.com) IBM Corp.
 *
 * Copyright (C) 2005-2011 FUJITA Tomonori <tomof@acm.org>
 * Copyright (C) 2010 Nicholas A. Bellinger <nab@kernel.org>
 *
 * Authors: Bryant G. Ly <bryantly@linux.vnet.ibm.com>
 * Authors: Michael Cyr <mikecyr@linux.vnet.ibm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 ****************************************************************************/

#define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/string.h>
#include <linux/delay.h>

#include <target/target_core_base.h>
#include <target/target_core_fabric.h>

#include <asm/hvcall.h>
#include <asm/vio.h>

#include <scsi/viosrp.h>

#include "ibmvscsi_tgt.h"

#define IBMVSCSIS_VERSION       "v0.2"

#define INITIAL_SRP_LIMIT       800
#define DEFAULT_MAX_SECTORS     256
#define MAX_TXU                 1024 * 1024

static uint max_vdma_size = MAX_H_COPY_RDMA;

static char system_id[SYS_ID_NAME_LEN] = "";
static char partition_name[PARTITION_NAMELEN] = "UNKNOWN";
static uint partition_number = -1;

/* Adapter list and lock to control it */
static DEFINE_SPINLOCK(ibmvscsis_dev_lock);
static LIST_HEAD(ibmvscsis_dev_list);

static long ibmvscsis_parse_command(struct scsi_info *vscsi,
                                    struct viosrp_crq *crq);

static void ibmvscsis_adapter_idle(struct scsi_info *vscsi);

static void ibmvscsis_determine_resid(struct se_cmd *se_cmd,
                                      struct srp_rsp *rsp)
{
        u32 residual_count = se_cmd->residual_count;

        if (!residual_count)
                return;

        if (se_cmd->se_cmd_flags & SCF_UNDERFLOW_BIT) {
                if (se_cmd->data_direction == DMA_TO_DEVICE) {
                        /* residual data from an underflow write */
                        rsp->flags = SRP_RSP_FLAG_DOUNDER;
                        rsp->data_out_res_cnt = cpu_to_be32(residual_count);
                } else if (se_cmd->data_direction == DMA_FROM_DEVICE) {
                        /* residual data from an underflow read */
                        rsp->flags = SRP_RSP_FLAG_DIUNDER;
                        rsp->data_in_res_cnt = cpu_to_be32(residual_count);
                }
        } else if (se_cmd->se_cmd_flags & SCF_OVERFLOW_BIT) {
                if (se_cmd->data_direction == DMA_TO_DEVICE) {
                        /* residual data from an overflow write */
                        rsp->flags = SRP_RSP_FLAG_DOOVER;
                        rsp->data_out_res_cnt = cpu_to_be32(residual_count);
                } else if (se_cmd->data_direction == DMA_FROM_DEVICE) {
                        /* residual data from an overflow read */
                        rsp->flags = SRP_RSP_FLAG_DIOVER;
                        rsp->data_in_res_cnt = cpu_to_be32(residual_count);
                }
        }
}

/**
 * connection_broken() - Determine if the connection to the client is good
 * @vscsi:      Pointer to our adapter structure
 *
 * This function attempts to send a ping MAD to the client. If the call to
 * queue the request returns H_CLOSED then the connection has been broken
 * and the function returns TRUE.
 *
 * EXECUTION ENVIRONMENT:
 *      Interrupt or Process environment
 */
static bool connection_broken(struct scsi_info *vscsi)
{
        struct viosrp_crq *crq;
        u64 buffer[2] = { 0, 0 };
        long h_return_code;
        bool rc = false;

        /* create a PING crq */
        crq = (struct viosrp_crq *)&buffer;
        crq->valid = VALID_CMD_RESP_EL;
        crq->format = MESSAGE_IN_CRQ;
        crq->status = PING;

        h_return_code = h_send_crq(vscsi->dds.unit_id,
                                   cpu_to_be64(buffer[MSG_HI]),
                                   cpu_to_be64(buffer[MSG_LOW]));

        pr_debug("connection_broken: rc %ld\n", h_return_code);

        if (h_return_code == H_CLOSED)
                rc = true;

        return rc;
}

/**
 * ibmvscsis_unregister_command_q() - Helper Function-Unregister Command Queue
 * @vscsi:      Pointer to our adapter structure
 *
 * This function calls h_free_q then frees the interrupt bit etc.
 * It must release the lock before doing so because of the time it can take
 * for h_free_crq in PHYP
 * NOTE: the caller must make sure that state and or flags will prevent
 *       interrupt handler from scheduling work.
 * NOTE: anyone calling this function may need to set the CRQ_CLOSED flag
 *       we can't do it here, because we don't have the lock
 *
 * EXECUTION ENVIRONMENT:
 *      Process level
 */
static long ibmvscsis_unregister_command_q(struct scsi_info *vscsi)
{
        long qrc;
        long rc = ADAPT_SUCCESS;
        int ticks = 0;

        do {
                qrc = h_free_crq(vscsi->dds.unit_id);
                switch (qrc) {
                case H_SUCCESS:
                        spin_lock_bh(&vscsi->intr_lock);
                        vscsi->flags &= ~PREP_FOR_SUSPEND_FLAGS;
                        spin_unlock_bh(&vscsi->intr_lock);
                        break;

                case H_HARDWARE:
                case H_PARAMETER:
                        dev_err(&vscsi->dev, "unregister_command_q: error from h_free_crq %ld\n",
                                qrc);
                        rc = ERROR;
                        break;

                case H_BUSY:
                case H_LONG_BUSY_ORDER_1_MSEC:
                        /* msleep not good for small values */
                        usleep_range(1000, 2000);
                        ticks += 1;
                        break;
                case H_LONG_BUSY_ORDER_10_MSEC:
                        usleep_range(10000, 20000);
                        ticks += 10;
                        break;
                case H_LONG_BUSY_ORDER_100_MSEC:
                        msleep(100);
                        ticks += 100;
                        break;
                case H_LONG_BUSY_ORDER_1_SEC:
                        ssleep(1);
                        ticks += 1000;
                        break;
                case H_LONG_BUSY_ORDER_10_SEC:
                        ssleep(10);
                        ticks += 10000;
                        break;
                case H_LONG_BUSY_ORDER_100_SEC:
                        ssleep(100);
                        ticks += 100000;
                        break;
                default:
                        dev_err(&vscsi->dev, "unregister_command_q: unknown error %ld from h_free_crq\n",
                                qrc);
                        rc = ERROR;
                        break;
                }

                /*
                 * dont wait more then 300 seconds
                 * ticks are in milliseconds more or less
                 */
                if (ticks > 300000 && qrc != H_SUCCESS) {
                        rc = ERROR;
                        dev_err(&vscsi->dev, "Excessive wait for h_free_crq\n");
                }
        } while (qrc != H_SUCCESS && rc == ADAPT_SUCCESS);

        pr_debug("Freeing CRQ: phyp rc %ld, rc %ld\n", qrc, rc);

        return rc;
}

/**
 * ibmvscsis_delete_client_info() - Helper function to Delete Client Info
 * @vscsi:      Pointer to our adapter structure
 * @client_closed:      True if client closed its queue
 *
 * Deletes information specific to the client when the client goes away
 *
 * EXECUTION ENVIRONMENT:
 *      Interrupt or Process
 */
static void ibmvscsis_delete_client_info(struct scsi_info *vscsi,
                                         bool client_closed)
{
        vscsi->client_cap = 0;

        /*
         * Some things we don't want to clear if we're closing the queue,
         * because some clients don't resend the host handshake when they
         * get a transport event.
         */
        if (client_closed)
                vscsi->client_data.os_type = 0;
}

/**
 * ibmvscsis_free_command_q() - Free Command Queue
 * @vscsi:      Pointer to our adapter structure
 *
 * This function calls unregister_command_q, then clears interrupts and
 * any pending interrupt acknowledgments associated with the command q.
 * It also clears memory if there is no error.
 *
 * PHYP did not meet the PAPR architecture so that we must give up the
 * lock. This causes a timing hole regarding state change.  To close the
 * hole this routine does accounting on any change that occurred during
 * the time the lock is not held.
 * NOTE: must give up and then acquire the interrupt lock, the caller must
 *       make sure that state and or flags will prevent interrupt handler from
 *       scheduling work.
 *
 * EXECUTION ENVIRONMENT:
 *      Process level, interrupt lock is held
 */
static long ibmvscsis_free_command_q(struct scsi_info *vscsi)
{
        int bytes;
        u32 flags_under_lock;
        u16 state_under_lock;
        long rc = ADAPT_SUCCESS;

        if (!(vscsi->flags & CRQ_CLOSED)) {
                vio_disable_interrupts(vscsi->dma_dev);

                state_under_lock = vscsi->new_state;
                flags_under_lock = vscsi->flags;
                vscsi->phyp_acr_state = 0;
                vscsi->phyp_acr_flags = 0;

                spin_unlock_bh(&vscsi->intr_lock);
                rc = ibmvscsis_unregister_command_q(vscsi);
                spin_lock_bh(&vscsi->intr_lock);

                if (state_under_lock != vscsi->new_state)
                        vscsi->phyp_acr_state = vscsi->new_state;

                vscsi->phyp_acr_flags = ((~flags_under_lock) & vscsi->flags);

                if (rc == ADAPT_SUCCESS) {
                        bytes = vscsi->cmd_q.size * PAGE_SIZE;
                        memset(vscsi->cmd_q.base_addr, 0, bytes);
                        vscsi->cmd_q.index = 0;
                        vscsi->flags |= CRQ_CLOSED;

                        ibmvscsis_delete_client_info(vscsi, false);
                }

                pr_debug("free_command_q: flags 0x%x, state 0x%hx, acr_flags 0x%x, acr_state 0x%hx\n",
                         vscsi->flags, vscsi->state, vscsi->phyp_acr_flags,
                         vscsi->phyp_acr_state);
        }
        return rc;
}

/**
 * ibmvscsis_cmd_q_dequeue() - Get valid Command element
 * @mask:       Mask to use in case index wraps
 * @current_index:      Current index into command queue
 * @base_addr:  Pointer to start of command queue
 *
 * Returns a pointer to a valid command element or NULL, if the command
 * queue is empty
 *
 * EXECUTION ENVIRONMENT:
 *      Interrupt environment, interrupt lock held
 */
static struct viosrp_crq *ibmvscsis_cmd_q_dequeue(uint mask,
                                                  uint *current_index,
                                                  struct viosrp_crq *base_addr)
{
        struct viosrp_crq *ptr;

        ptr = base_addr + *current_index;

        if (ptr->valid) {
                *current_index = (*current_index + 1) & mask;
                dma_rmb();
        } else {
                ptr = NULL;
        }

        return ptr;
}

/**
 * ibmvscsis_send_init_message() - send initialize message to the client
 * @vscsi:      Pointer to our adapter structure
 * @format:     Which Init Message format to send
 *
 * EXECUTION ENVIRONMENT:
 *      Interrupt environment interrupt lock held
 */
static long ibmvscsis_send_init_message(struct scsi_info *vscsi, u8 format)
{
        struct viosrp_crq *crq;
        u64 buffer[2] = { 0, 0 };
        long rc;

        crq = (struct viosrp_crq *)&buffer;
        crq->valid = VALID_INIT_MSG;
        crq->format = format;
        rc = h_send_crq(vscsi->dds.unit_id, cpu_to_be64(buffer[MSG_HI]),
                        cpu_to_be64(buffer[MSG_LOW]));

        return rc;
}

/**
 * ibmvscsis_check_init_msg() - Check init message valid
 * @vscsi:      Pointer to our adapter structure
 * @format:     Pointer to return format of Init Message, if any.
 *              Set to UNUSED_FORMAT if no Init Message in queue.
 *
 * Checks if an initialize message was queued by the initiatior
 * after the queue was created and before the interrupt was enabled.
 *
 * EXECUTION ENVIRONMENT:
 *      Process level only, interrupt lock held
 */
static long ibmvscsis_check_init_msg(struct scsi_info *vscsi, uint *format)
{
        struct viosrp_crq *crq;
        long rc = ADAPT_SUCCESS;

        crq = ibmvscsis_cmd_q_dequeue(vscsi->cmd_q.mask, &vscsi->cmd_q.index,
                                      vscsi->cmd_q.base_addr);
        if (!crq) {
                *format = (uint)UNUSED_FORMAT;
        } else if (crq->valid == VALID_INIT_MSG && crq->format == INIT_MSG) {
                *format = (uint)INIT_MSG;
                crq->valid = INVALIDATE_CMD_RESP_EL;
                dma_rmb();

                /*
                 * the caller has ensured no initialize message was
                 * sent after the queue was
                 * created so there should be no other message on the queue.
                 */
                crq = ibmvscsis_cmd_q_dequeue(vscsi->cmd_q.mask,
                                              &vscsi->cmd_q.index,
                                              vscsi->cmd_q.base_addr);
                if (crq) {
                        *format = (uint)(crq->format);
                        rc = ERROR;
                        crq->valid = INVALIDATE_CMD_RESP_EL;
                        dma_rmb();
                }
        } else {
                *format = (uint)(crq->format);
                rc = ERROR;
                crq->valid = INVALIDATE_CMD_RESP_EL;
                dma_rmb();
        }

        return rc;
}

/**
 * ibmvscsis_disconnect() - Helper function to disconnect
 * @work:       Pointer to work_struct, gives access to our adapter structure
 *
 * An error has occurred or the driver received a Transport event,
 * and the driver is requesting that the command queue be de-registered
 * in a safe manner. If there is no outstanding I/O then we can stop the
 * queue. If we are restarting the queue it will be reflected in the
 * the state of the adapter.
 *
 * EXECUTION ENVIRONMENT:
 *      Process environment
 */
static void ibmvscsis_disconnect(struct work_struct *work)
{
        struct scsi_info *vscsi = container_of(work, struct scsi_info,
                                               proc_work);
        u16 new_state;
        bool wait_idle = false;

        spin_lock_bh(&vscsi->intr_lock);
        new_state = vscsi->new_state;
        vscsi->new_state = 0;

        vscsi->flags |= DISCONNECT_SCHEDULED;
        vscsi->flags &= ~SCHEDULE_DISCONNECT;

        pr_debug("disconnect: flags 0x%x, state 0x%hx\n", vscsi->flags,
                 vscsi->state);

        /*
         * check which state we are in and see if we
         * should transitition to the new state
         */
        switch (vscsi->state) {
        /* Should never be called while in this state. */
        case NO_QUEUE:
        /*
         * Can never transition from this state;
         * igonore errors and logout.
         */
        case UNCONFIGURING:
                break;

        /* can transition from this state to UNCONFIGURING */
        case ERR_DISCONNECT:
                if (new_state == UNCONFIGURING)
                        vscsi->state = new_state;
                break;

        /*
         * Can transition from this state to to unconfiguring
         * or err disconnect.
         */
        case ERR_DISCONNECT_RECONNECT:
                switch (new_state) {
                case UNCONFIGURING:
                case ERR_DISCONNECT:
                        vscsi->state = new_state;
                        break;

                case WAIT_IDLE:
                        break;
                default:
                        break;
                }
                break;

        /* can transition from this state to UNCONFIGURING */
        case ERR_DISCONNECTED:
                if (new_state == UNCONFIGURING)
                        vscsi->state = new_state;
                break;

        case WAIT_ENABLED:
                switch (new_state) {
                case UNCONFIGURING:
                        vscsi->state = new_state;
                        vscsi->flags |= RESPONSE_Q_DOWN;
                        vscsi->flags &= ~(SCHEDULE_DISCONNECT |
                                          DISCONNECT_SCHEDULED);
                        dma_rmb();
                        if (vscsi->flags & CFG_SLEEPING) {
                                vscsi->flags &= ~CFG_SLEEPING;
                                complete(&vscsi->unconfig);
                        }
                        break;

                /* should never happen */
                case ERR_DISCONNECT:
                case ERR_DISCONNECT_RECONNECT:
                case WAIT_IDLE:
                        dev_err(&vscsi->dev, "disconnect: invalid state %d for WAIT_IDLE\n",
                                vscsi->state);
                        break;
                }
                break;

        case WAIT_IDLE:
                switch (new_state) {
                case UNCONFIGURING:
                        vscsi->flags |= RESPONSE_Q_DOWN;
                        vscsi->state = new_state;
                        vscsi->flags &= ~(SCHEDULE_DISCONNECT |
                                          DISCONNECT_SCHEDULED);
                        ibmvscsis_free_command_q(vscsi);
                        break;
                case ERR_DISCONNECT:
                case ERR_DISCONNECT_RECONNECT:
                        vscsi->state = new_state;
                        break;
                }
                break;

        /*
         * Initiator has not done a successful srp login
         * or has done a successful srp logout ( adapter was not
         * busy). In the first case there can be responses queued
         * waiting for space on the initiators response queue (MAD)
         * The second case the adapter is idle. Assume the worse case,
         * i.e. the second case.
         */
        case WAIT_CONNECTION:
        case CONNECTED:
        case SRP_PROCESSING:
                wait_idle = true;
                vscsi->state = new_state;
                break;

        /* can transition from this state to UNCONFIGURING */
        case UNDEFINED:
                if (new_state == UNCONFIGURING)
                        vscsi->state = new_state;
                break;
        default:
                break;
        }

        if (wait_idle) {
                pr_debug("disconnect start wait, active %d, sched %d\n",
                         (int)list_empty(&vscsi->active_q),
                         (int)list_empty(&vscsi->schedule_q));
                if (!list_empty(&vscsi->active_q) ||
                    !list_empty(&vscsi->schedule_q)) {
                        vscsi->flags |= WAIT_FOR_IDLE;
                        pr_debug("disconnect flags 0x%x\n", vscsi->flags);
                        /*
                         * This routine is can not be called with the interrupt
                         * lock held.
                         */
                        spin_unlock_bh(&vscsi->intr_lock);
                        wait_for_completion(&vscsi->wait_idle);
                        spin_lock_bh(&vscsi->intr_lock);
                }
                pr_debug("disconnect stop wait\n");

                ibmvscsis_adapter_idle(vscsi);
        }

        spin_unlock_bh(&vscsi->intr_lock);
}

/**
 * ibmvscsis_post_disconnect() - Schedule the disconnect
 * @vscsi:      Pointer to our adapter structure
 * @new_state:  State to move to after disconnecting
 * @flag_bits:  Flags to turn on in adapter structure
 *
 * If it's already been scheduled, then see if we need to "upgrade"
 * the new state (if the one passed in is more "severe" than the
 * previous one).
 *
 * PRECONDITION:
 *      interrupt lock is held
 */
static void ibmvscsis_post_disconnect(struct scsi_info *vscsi, uint new_state,
                                      uint flag_bits)
{
        uint state;

        /* check the validity of the new state */
        switch (new_state) {
        case UNCONFIGURING:
        case ERR_DISCONNECT:
        case ERR_DISCONNECT_RECONNECT:
        case WAIT_IDLE:
                break;

        default:
                dev_err(&vscsi->dev, "post_disconnect: Invalid new state %d\n",
                        new_state);
                return;
        }

        vscsi->flags |= flag_bits;

        pr_debug("post_disconnect: new_state 0x%x, flag_bits 0x%x, vscsi->flags 0x%x, state %hx\n",
                 new_state, flag_bits, vscsi->flags, vscsi->state);

        if (!(vscsi->flags & (DISCONNECT_SCHEDULED | SCHEDULE_DISCONNECT))) {
                vscsi->flags |= SCHEDULE_DISCONNECT;
                vscsi->new_state = new_state;

                INIT_WORK(&vscsi->proc_work, ibmvscsis_disconnect);
                (void)queue_work(vscsi->work_q, &vscsi->proc_work);
        } else {
                if (vscsi->new_state)
                        state = vscsi->new_state;
                else
                        state = vscsi->state;

                switch (state) {
                case NO_QUEUE:
                case UNCONFIGURING:
                        break;

                case ERR_DISCONNECTED:
                case ERR_DISCONNECT:
                case UNDEFINED:
                        if (new_state == UNCONFIGURING)
                                vscsi->new_state = new_state;
                        break;

                case ERR_DISCONNECT_RECONNECT:
                        switch (new_state) {
                        case UNCONFIGURING:
                        case ERR_DISCONNECT:
                                vscsi->new_state = new_state;
                                break;
                        default:
                                break;
                        }
                        break;

                case WAIT_ENABLED:
                case WAIT_IDLE:
                case WAIT_CONNECTION:
                case CONNECTED:
                case SRP_PROCESSING:
                        vscsi->new_state = new_state;
                        break;

                default:
                        break;
                }
        }

        pr_debug("Leaving post_disconnect: flags 0x%x, new_state 0x%x\n",
                 vscsi->flags, vscsi->new_state);
}

/**
 * ibmvscsis_handle_init_compl_msg() - Respond to an Init Complete Message
 * @vscsi:      Pointer to our adapter structure
 *
 * Must be called with interrupt lock held.
 */
static long ibmvscsis_handle_init_compl_msg(struct scsi_info *vscsi)
{
        long rc = ADAPT_SUCCESS;

        switch (vscsi->state) {
        case NO_QUEUE:
        case ERR_DISCONNECT:
        case ERR_DISCONNECT_RECONNECT:
        case ERR_DISCONNECTED:
        case UNCONFIGURING:
        case UNDEFINED:
                rc = ERROR;
                break;

        case WAIT_CONNECTION:
                vscsi->state = CONNECTED;
                break;

        case WAIT_IDLE:
        case SRP_PROCESSING:
        case CONNECTED:
        case WAIT_ENABLED:
        default:
                rc = ERROR;
                dev_err(&vscsi->dev, "init_msg: invalid state %d to get init compl msg\n",
                        vscsi->state);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT, 0);
                break;
        }

        return rc;
}

/**
 * ibmvscsis_handle_init_msg() - Respond to an Init Message
 * @vscsi:      Pointer to our adapter structure
 *
 * Must be called with interrupt lock held.
 */
static long ibmvscsis_handle_init_msg(struct scsi_info *vscsi)
{
        long rc = ADAPT_SUCCESS;

        switch (vscsi->state) {
        case WAIT_CONNECTION:
                rc = ibmvscsis_send_init_message(vscsi, INIT_COMPLETE_MSG);
                switch (rc) {
                case H_SUCCESS:
                        vscsi->state = CONNECTED;
                        break;

                case H_PARAMETER:
                        dev_err(&vscsi->dev, "init_msg: failed to send, rc %ld\n",
                                rc);
                        ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT, 0);
                        break;

                case H_DROPPED:
                        dev_err(&vscsi->dev, "init_msg: failed to send, rc %ld\n",
                                rc);
                        rc = ERROR;
                        ibmvscsis_post_disconnect(vscsi,
                                                  ERR_DISCONNECT_RECONNECT, 0);
                        break;

                case H_CLOSED:
                        pr_warn("init_msg: failed to send, rc %ld\n", rc);
                        rc = 0;
                        break;
                }
                break;

        case UNDEFINED:
                rc = ERROR;
                break;

        case UNCONFIGURING:
                break;

        case WAIT_ENABLED:
        case CONNECTED:
        case SRP_PROCESSING:
        case WAIT_IDLE:
        case NO_QUEUE:
        case ERR_DISCONNECT:
        case ERR_DISCONNECT_RECONNECT:
        case ERR_DISCONNECTED:
        default:
                rc = ERROR;
                dev_err(&vscsi->dev, "init_msg: invalid state %d to get init msg\n",
                        vscsi->state);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT, 0);
                break;
        }

        return rc;
}

/**
 * ibmvscsis_init_msg() - Respond to an init message
 * @vscsi:      Pointer to our adapter structure
 * @crq:        Pointer to CRQ element containing the Init Message
 *
 * EXECUTION ENVIRONMENT:
 *      Interrupt, interrupt lock held
 */
static long ibmvscsis_init_msg(struct scsi_info *vscsi, struct viosrp_crq *crq)
{
        long rc = ADAPT_SUCCESS;

        pr_debug("init_msg: state 0x%hx\n", vscsi->state);

        rc = h_vioctl(vscsi->dds.unit_id, H_GET_PARTNER_INFO,
                      (u64)vscsi->map_ioba | ((u64)PAGE_SIZE << 32), 0, 0, 0,
                      0);
        if (rc == H_SUCCESS) {
                vscsi->client_data.partition_number =
                        be64_to_cpu(*(u64 *)vscsi->map_buf);
                pr_debug("init_msg, part num %d\n",
                         vscsi->client_data.partition_number);
        } else {
                pr_debug("init_msg h_vioctl rc %ld\n", rc);
                rc = ADAPT_SUCCESS;
        }

        if (crq->format == INIT_MSG) {
                rc = ibmvscsis_handle_init_msg(vscsi);
        } else if (crq->format == INIT_COMPLETE_MSG) {
                rc = ibmvscsis_handle_init_compl_msg(vscsi);
        } else {
                rc = ERROR;
                dev_err(&vscsi->dev, "init_msg: invalid format %d\n",
                        (uint)crq->format);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT, 0);
        }

        return rc;
}

/**
 * ibmvscsis_establish_new_q() - Establish new CRQ queue
 * @vscsi:      Pointer to our adapter structure
 *
 * Must be called with interrupt lock held.
 */
static long ibmvscsis_establish_new_q(struct scsi_info *vscsi)
{
        long rc = ADAPT_SUCCESS;
        uint format;

        rc = h_vioctl(vscsi->dds.unit_id, H_ENABLE_PREPARE_FOR_SUSPEND, 30000,
                      0, 0, 0, 0);
        if (rc == H_SUCCESS)
                vscsi->flags |= PREP_FOR_SUSPEND_ENABLED;
        else if (rc != H_NOT_FOUND)
                pr_err("Error from Enable Prepare for Suspend: %ld\n", rc);

        vscsi->flags &= PRESERVE_FLAG_FIELDS;
        vscsi->rsp_q_timer.timer_pops = 0;
        vscsi->debit = 0;
        vscsi->credit = 0;

        rc = vio_enable_interrupts(vscsi->dma_dev);
        if (rc) {
                pr_warn("establish_new_q: failed to enable interrupts, rc %ld\n",
                        rc);
                return rc;
        }

        rc = ibmvscsis_check_init_msg(vscsi, &format);
        if (rc) {
                dev_err(&vscsi->dev, "establish_new_q: check_init_msg failed, rc %ld\n",
                        rc);
                return rc;
        }

        if (format == UNUSED_FORMAT) {
                rc = ibmvscsis_send_init_message(vscsi, INIT_MSG);
                switch (rc) {
                case H_SUCCESS:
                case H_DROPPED:
                case H_CLOSED:
                        rc = ADAPT_SUCCESS;
                        break;

                case H_PARAMETER:
                case H_HARDWARE:
                        break;

                default:
                        vscsi->state = UNDEFINED;
                        rc = H_HARDWARE;
                        break;
                }
        } else if (format == INIT_MSG) {
                rc = ibmvscsis_handle_init_msg(vscsi);
        }

        return rc;
}

/**
 * ibmvscsis_reset_queue() - Reset CRQ Queue
 * @vscsi:      Pointer to our adapter structure
 *
 * This function calls h_free_q and then calls h_reg_q and does all
 * of the bookkeeping to get us back to where we can communicate.
 *
 * Actually, we don't always call h_free_crq.  A problem was discovered
 * where one partition would close and reopen his queue, which would
 * cause his partner to get a transport event, which would cause him to
 * close and reopen his queue, which would cause the original partition
 * to get a transport event, etc., etc.  To prevent this, we don't
 * actually close our queue if the client initiated the reset, (i.e.
 * either we got a transport event or we have detected that the client's
 * queue is gone)
 *
 * EXECUTION ENVIRONMENT:
 *      Process environment, called with interrupt lock held
 */
static void ibmvscsis_reset_queue(struct scsi_info *vscsi)
{
        int bytes;
        long rc = ADAPT_SUCCESS;

        pr_debug("reset_queue: flags 0x%x\n", vscsi->flags);

        /* don't reset, the client did it for us */
        if (vscsi->flags & (CLIENT_FAILED | TRANS_EVENT)) {
                vscsi->flags &= PRESERVE_FLAG_FIELDS;
                vscsi->rsp_q_timer.timer_pops = 0;
                vscsi->debit = 0;
                vscsi->credit = 0;
                vscsi->state = WAIT_CONNECTION;
                vio_enable_interrupts(vscsi->dma_dev);
        } else {
                rc = ibmvscsis_free_command_q(vscsi);
                if (rc == ADAPT_SUCCESS) {
                        vscsi->state = WAIT_CONNECTION;

                        bytes = vscsi->cmd_q.size * PAGE_SIZE;
                        rc = h_reg_crq(vscsi->dds.unit_id,
                                       vscsi->cmd_q.crq_token, bytes);
                        if (rc == H_CLOSED || rc == H_SUCCESS) {
                                rc = ibmvscsis_establish_new_q(vscsi);
                        }

                        if (rc != ADAPT_SUCCESS) {
                                pr_debug("reset_queue: reg_crq rc %ld\n", rc);

                                vscsi->state = ERR_DISCONNECTED;
                                vscsi->flags |= RESPONSE_Q_DOWN;
                                ibmvscsis_free_command_q(vscsi);
                        }
                } else {
                        vscsi->state = ERR_DISCONNECTED;
                        vscsi->flags |= RESPONSE_Q_DOWN;
                }
        }
}

/**
 * ibmvscsis_free_cmd_resources() - Free command resources
 * @vscsi:      Pointer to our adapter structure
 * @cmd:        Command which is not longer in use
 *
 * Must be called with interrupt lock held.
 */
static void ibmvscsis_free_cmd_resources(struct scsi_info *vscsi,
                                         struct ibmvscsis_cmd *cmd)
{
        struct iu_entry *iue = cmd->iue;

        switch (cmd->type) {
        case TASK_MANAGEMENT:
        case SCSI_CDB:
                /*
                 * When the queue goes down this value is cleared, so it
                 * cannot be cleared in this general purpose function.
                 */
                if (vscsi->debit)
                        vscsi->debit -= 1;
                break;
        case ADAPTER_MAD:
                vscsi->flags &= ~PROCESSING_MAD;
                break;
        case UNSET_TYPE:
                break;
        default:
                dev_err(&vscsi->dev, "free_cmd_resources unknown type %d\n",
                        cmd->type);
                break;
        }

        cmd->iue = NULL;
        list_add_tail(&cmd->list, &vscsi->free_cmd);
        srp_iu_put(iue);

        if (list_empty(&vscsi->active_q) && list_empty(&vscsi->schedule_q) &&
            list_empty(&vscsi->waiting_rsp) && (vscsi->flags & WAIT_FOR_IDLE)) {
                vscsi->flags &= ~WAIT_FOR_IDLE;
                complete(&vscsi->wait_idle);
        }
}

/**
 * ibmvscsis_ready_for_suspend() - Helper function to call VIOCTL
 * @vscsi:      Pointer to our adapter structure
 * @idle:       Indicates whether we were called from adapter_idle.  This
 *              is important to know if we need to do a disconnect, since if
 *              we're called from adapter_idle, we're still processing the
 *              current disconnect, so we can't just call post_disconnect.
 *
 * This function is called when the adapter is idle when phyp has sent
 * us a Prepare for Suspend Transport Event.
 *
 * EXECUTION ENVIRONMENT:
 *      Process or interrupt environment called with interrupt lock held
 */
static long ibmvscsis_ready_for_suspend(struct scsi_info *vscsi, bool idle)
{
        long rc = 0;
        struct viosrp_crq *crq;

        /* See if there is a Resume event in the queue */
        crq = vscsi->cmd_q.base_addr + vscsi->cmd_q.index;

        pr_debug("ready_suspend: flags 0x%x, state 0x%hx crq_valid:%x\n",
                 vscsi->flags, vscsi->state, (int)crq->valid);

        if (!(vscsi->flags & PREP_FOR_SUSPEND_ABORTED) && !(crq->valid)) {
                rc = h_vioctl(vscsi->dds.unit_id, H_READY_FOR_SUSPEND, 0, 0, 0,
                              0, 0);
                if (rc) {
                        pr_err("Ready for Suspend Vioctl failed: %ld\n", rc);
                        rc = 0;
                }
        } else if (((vscsi->flags & PREP_FOR_SUSPEND_OVERWRITE) &&
                    (vscsi->flags & PREP_FOR_SUSPEND_ABORTED)) ||
                   ((crq->valid) && ((crq->valid != VALID_TRANS_EVENT) ||
                                     (crq->format != RESUME_FROM_SUSP)))) {
                if (idle) {
                        vscsi->state = ERR_DISCONNECT_RECONNECT;
                        ibmvscsis_reset_queue(vscsi);
                        rc = -1;
                } else if (vscsi->state == CONNECTED) {
                        ibmvscsis_post_disconnect(vscsi,
                                                  ERR_DISCONNECT_RECONNECT, 0);
                }

                vscsi->flags &= ~PREP_FOR_SUSPEND_OVERWRITE;

                if ((crq->valid) && ((crq->valid != VALID_TRANS_EVENT) ||
                                     (crq->format != RESUME_FROM_SUSP)))
                        pr_err("Invalid element in CRQ after Prepare for Suspend");
        }

        vscsi->flags &= ~(PREP_FOR_SUSPEND_PENDING | PREP_FOR_SUSPEND_ABORTED);

        return rc;
}

/**
 * ibmvscsis_trans_event() - Handle a Transport Event
 * @vscsi:      Pointer to our adapter structure
 * @crq:        Pointer to CRQ entry containing the Transport Event
 *
 * Do the logic to close the I_T nexus.  This function may not
 * behave to specification.
 *
 * EXECUTION ENVIRONMENT:
 *      Interrupt, interrupt lock held
 */
static long ibmvscsis_trans_event(struct scsi_info *vscsi,
                                  struct viosrp_crq *crq)
{
        long rc = ADAPT_SUCCESS;

        pr_debug("trans_event: format %d, flags 0x%x, state 0x%hx\n",
                 (int)crq->format, vscsi->flags, vscsi->state);

        switch (crq->format) {
        case MIGRATED:
        case PARTNER_FAILED:
        case PARTNER_DEREGISTER:
                ibmvscsis_delete_client_info(vscsi, true);
                if (crq->format == MIGRATED)
                        vscsi->flags &= ~PREP_FOR_SUSPEND_OVERWRITE;
                switch (vscsi->state) {
                case NO_QUEUE:
                case ERR_DISCONNECTED:
                case UNDEFINED:
                        break;

                case UNCONFIGURING:
                        vscsi->flags |= (RESPONSE_Q_DOWN | TRANS_EVENT);
                        break;

                case WAIT_ENABLED:
                        break;

                case WAIT_CONNECTION:
                        break;

                case CONNECTED:
                        ibmvscsis_post_disconnect(vscsi, WAIT_IDLE,
                                                  (RESPONSE_Q_DOWN |
                                                   TRANS_EVENT));
                        break;

                case SRP_PROCESSING:
                        if ((vscsi->debit > 0) ||
                            !list_empty(&vscsi->schedule_q) ||
                            !list_empty(&vscsi->waiting_rsp) ||
                            !list_empty(&vscsi->active_q)) {
                                pr_debug("debit %d, sched %d, wait %d, active %d\n",
                                         vscsi->debit,
                                         (int)list_empty(&vscsi->schedule_q),
                                         (int)list_empty(&vscsi->waiting_rsp),
                                         (int)list_empty(&vscsi->active_q));
                                pr_warn("connection lost with outstanding work\n");
                        } else {
                                pr_debug("trans_event: SRP Processing, but no outstanding work\n");
                        }

                        ibmvscsis_post_disconnect(vscsi, WAIT_IDLE,
                                                  (RESPONSE_Q_DOWN |
                                                   TRANS_EVENT));
                        break;

                case ERR_DISCONNECT:
                case ERR_DISCONNECT_RECONNECT:
                case WAIT_IDLE:
                        vscsi->flags |= (RESPONSE_Q_DOWN | TRANS_EVENT);
                        break;
                }
                break;

        case PREPARE_FOR_SUSPEND:
                pr_debug("Prep for Suspend, crq status = 0x%x\n",
                         (int)crq->status);
                switch (vscsi->state) {
                case ERR_DISCONNECTED:
                case WAIT_CONNECTION:
                case CONNECTED:
                        ibmvscsis_ready_for_suspend(vscsi, false);
                        break;
                case SRP_PROCESSING:
                        vscsi->resume_state = vscsi->state;
                        vscsi->flags |= PREP_FOR_SUSPEND_PENDING;
                        if (crq->status == CRQ_ENTRY_OVERWRITTEN)
                                vscsi->flags |= PREP_FOR_SUSPEND_OVERWRITE;
                        ibmvscsis_post_disconnect(vscsi, WAIT_IDLE, 0);
                        break;
                case NO_QUEUE:
                case UNDEFINED:
                case UNCONFIGURING:
                case WAIT_ENABLED:
                case ERR_DISCONNECT:
                case ERR_DISCONNECT_RECONNECT:
                case WAIT_IDLE:
                        pr_err("Invalid state for Prepare for Suspend Trans Event: 0x%x\n",
                               vscsi->state);
                        break;
                }
                break;

        case RESUME_FROM_SUSP:
                pr_debug("Resume from Suspend, crq status = 0x%x\n",
                         (int)crq->status);
                if (vscsi->flags & PREP_FOR_SUSPEND_PENDING) {
                        vscsi->flags |= PREP_FOR_SUSPEND_ABORTED;
                } else {
                        if ((crq->status == CRQ_ENTRY_OVERWRITTEN) ||
                            (vscsi->flags & PREP_FOR_SUSPEND_OVERWRITE)) {
                                ibmvscsis_post_disconnect(vscsi,
                                                          ERR_DISCONNECT_RECONNECT,
                                                          0);
                                vscsi->flags &= ~PREP_FOR_SUSPEND_OVERWRITE;
                        }
                }
                break;

        default:
                rc = ERROR;
                dev_err(&vscsi->dev, "trans_event: invalid format %d\n",
                        (uint)crq->format);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT,
                                          RESPONSE_Q_DOWN);
                break;
        }

        rc = vscsi->flags & SCHEDULE_DISCONNECT;

        pr_debug("Leaving trans_event: flags 0x%x, state 0x%hx, rc %ld\n",
                 vscsi->flags, vscsi->state, rc);

        return rc;
}

/**
 * ibmvscsis_poll_cmd_q() - Poll Command Queue
 * @vscsi:      Pointer to our adapter structure
 *
 * Called to handle command elements that may have arrived while
 * interrupts were disabled.
 *
 * EXECUTION ENVIRONMENT:
 *      intr_lock must be held
 */
static void ibmvscsis_poll_cmd_q(struct scsi_info *vscsi)
{
        struct viosrp_crq *crq;
        long rc;
        bool ack = true;
        volatile u8 valid;

        pr_debug("poll_cmd_q: flags 0x%x, state 0x%hx, q index %ud\n",
                 vscsi->flags, vscsi->state, vscsi->cmd_q.index);

        rc = vscsi->flags & SCHEDULE_DISCONNECT;
        crq = vscsi->cmd_q.base_addr + vscsi->cmd_q.index;
        valid = crq->valid;
        dma_rmb();

        while (valid) {
poll_work:
                vscsi->cmd_q.index =
                        (vscsi->cmd_q.index + 1) & vscsi->cmd_q.mask;

                if (!rc) {
                        rc = ibmvscsis_parse_command(vscsi, crq);
                } else {
                        if ((uint)crq->valid == VALID_TRANS_EVENT) {
                                /*
                                 * must service the transport layer events even
                                 * in an error state, dont break out until all
                                 * the consecutive transport events have been
                                 * processed
                                 */
                                rc = ibmvscsis_trans_event(vscsi, crq);
                        } else if (vscsi->flags & TRANS_EVENT) {
                                /*
                                 * if a tranport event has occurred leave
                                 * everything but transport events on the queue
                                 */
                                pr_debug("poll_cmd_q, ignoring\n");

                                /*
                                 * need to decrement the queue index so we can
                                 * look at the elment again
                                 */
                                if (vscsi->cmd_q.index)
                                        vscsi->cmd_q.index -= 1;
                                else
                                        /*
                                         * index is at 0 it just wrapped.
                                         * have it index last element in q
                                         */
                                        vscsi->cmd_q.index = vscsi->cmd_q.mask;
                                break;
                        }
                }

                crq->valid = INVALIDATE_CMD_RESP_EL;

                crq = vscsi->cmd_q.base_addr + vscsi->cmd_q.index;
                valid = crq->valid;
                dma_rmb();
        }

        if (!rc) {
                if (ack) {
                        vio_enable_interrupts(vscsi->dma_dev);
                        ack = false;
                        pr_debug("poll_cmd_q, reenabling interrupts\n");
                }
                valid = crq->valid;
                dma_rmb();
                if (valid)
                        goto poll_work;
        }

        pr_debug("Leaving poll_cmd_q: rc %ld\n", rc);
}

/**
 * ibmvscsis_free_cmd_qs() - Free elements in queue
 * @vscsi:      Pointer to our adapter structure
 *
 * Free all of the elements on all queues that are waiting for
 * whatever reason.
 *
 * PRECONDITION:
 *      Called with interrupt lock held
 */
static void ibmvscsis_free_cmd_qs(struct scsi_info *vscsi)
{
        struct ibmvscsis_cmd *cmd, *nxt;

        pr_debug("free_cmd_qs: waiting_rsp empty %d, timer starter %d\n",
                 (int)list_empty(&vscsi->waiting_rsp),
                 vscsi->rsp_q_timer.started);

        list_for_each_entry_safe(cmd, nxt, &vscsi->waiting_rsp, list) {
                list_del(&cmd->list);
                ibmvscsis_free_cmd_resources(vscsi, cmd);
        }
}

/**
 * ibmvscsis_get_free_cmd() - Get free command from list
 * @vscsi:      Pointer to our adapter structure
 *
 * Must be called with interrupt lock held.
 */
static struct ibmvscsis_cmd *ibmvscsis_get_free_cmd(struct scsi_info *vscsi)
{
        struct ibmvscsis_cmd *cmd = NULL;
        struct iu_entry *iue;

        iue = srp_iu_get(&vscsi->target);
        if (iue) {
                cmd = list_first_entry_or_null(&vscsi->free_cmd,
                                               struct ibmvscsis_cmd, list);
                if (cmd) {
                        if (cmd->abort_cmd)
                                cmd->abort_cmd = NULL;
                        cmd->flags &= ~(DELAY_SEND);
                        list_del(&cmd->list);
                        cmd->iue = iue;
                        cmd->type = UNSET_TYPE;
                        memset(&cmd->se_cmd, 0, sizeof(cmd->se_cmd));
                } else {
                        srp_iu_put(iue);
                }
        }

        return cmd;
}

/**
 * ibmvscsis_adapter_idle() - Helper function to handle idle adapter
 * @vscsi:      Pointer to our adapter structure
 *
 * This function is called when the adapter is idle when the driver
 * is attempting to clear an error condition.
 * The adapter is considered busy if any of its cmd queues
 * are non-empty. This function can be invoked
 * from the off level disconnect function.
 *
 * EXECUTION ENVIRONMENT:
 *      Process environment called with interrupt lock held
 */
static void ibmvscsis_adapter_idle(struct scsi_info *vscsi)
{
        int free_qs = false;
        long rc = 0;

        pr_debug("adapter_idle: flags 0x%x, state 0x%hx\n", vscsi->flags,
                 vscsi->state);

        /* Only need to free qs if we're disconnecting from client */
        if (vscsi->state != WAIT_CONNECTION || vscsi->flags & TRANS_EVENT)
                free_qs = true;

        switch (vscsi->state) {
        case UNCONFIGURING:
                ibmvscsis_free_command_q(vscsi);
                dma_rmb();
                isync();
                if (vscsi->flags & CFG_SLEEPING) {
                        vscsi->flags &= ~CFG_SLEEPING;
                        complete(&vscsi->unconfig);
                }
                break;
        case ERR_DISCONNECT_RECONNECT:
                ibmvscsis_reset_queue(vscsi);
                pr_debug("adapter_idle, disc_rec: flags 0x%x\n", vscsi->flags);
                break;

        case ERR_DISCONNECT:
                ibmvscsis_free_command_q(vscsi);
                vscsi->flags &= ~(SCHEDULE_DISCONNECT | DISCONNECT_SCHEDULED);
                vscsi->flags |= RESPONSE_Q_DOWN;
                if (vscsi->tport.enabled)
                        vscsi->state = ERR_DISCONNECTED;
                else
                        vscsi->state = WAIT_ENABLED;
                pr_debug("adapter_idle, disc: flags 0x%x, state 0x%hx\n",
                         vscsi->flags, vscsi->state);
                break;

        case WAIT_IDLE:
                vscsi->rsp_q_timer.timer_pops = 0;
                vscsi->debit = 0;
                vscsi->credit = 0;
                if (vscsi->flags & PREP_FOR_SUSPEND_PENDING) {
                        vscsi->state = vscsi->resume_state;
                        vscsi->resume_state = 0;
                        rc = ibmvscsis_ready_for_suspend(vscsi, true);
                        vscsi->flags &= ~DISCONNECT_SCHEDULED;
                        if (rc)
                                break;
                } else if (vscsi->flags & TRANS_EVENT) {
                        vscsi->state = WAIT_CONNECTION;
                        vscsi->flags &= PRESERVE_FLAG_FIELDS;
                } else {
                        vscsi->state = CONNECTED;
                        vscsi->flags &= ~DISCONNECT_SCHEDULED;
                }

                pr_debug("adapter_idle, wait: flags 0x%x, state 0x%hx\n",
                         vscsi->flags, vscsi->state);
                ibmvscsis_poll_cmd_q(vscsi);
                break;

        case ERR_DISCONNECTED:
                vscsi->flags &= ~DISCONNECT_SCHEDULED;
                pr_debug("adapter_idle, disconnected: flags 0x%x, state 0x%hx\n",
                         vscsi->flags, vscsi->state);
                break;

        default:
                dev_err(&vscsi->dev, "adapter_idle: in invalid state %d\n",
                        vscsi->state);
                break;
        }

        if (free_qs)
                ibmvscsis_free_cmd_qs(vscsi);

        /*
         * There is a timing window where we could lose a disconnect request.
         * The known path to this window occurs during the DISCONNECT_RECONNECT
         * case above: reset_queue calls free_command_q, which will release the
         * interrupt lock.  During that time, a new post_disconnect call can be
         * made with a "more severe" state (DISCONNECT or UNCONFIGURING).
         * Because the DISCONNECT_SCHEDULED flag is already set, post_disconnect
         * will only set the new_state.  Now free_command_q reacquires the intr
         * lock and clears the DISCONNECT_SCHEDULED flag (using PRESERVE_FLAG_
         * FIELDS), and the disconnect is lost.  This is particularly bad when
         * the new disconnect was for UNCONFIGURING, since the unconfigure hangs
         * forever.
         * Fix is that free command queue sets acr state and acr flags if there
         * is a change under the lock
         * note free command queue writes to this state it clears it
         * before releasing the lock, different drivers call the free command
         * queue different times so dont initialize above
         */
        if (vscsi->phyp_acr_state != 0) {
                /*
                 * set any bits in flags that may have been cleared by
                 * a call to free command queue in switch statement
                 * or reset queue
                 */
                vscsi->flags |= vscsi->phyp_acr_flags;
                ibmvscsis_post_disconnect(vscsi, vscsi->phyp_acr_state, 0);
                vscsi->phyp_acr_state = 0;
                vscsi->phyp_acr_flags = 0;

                pr_debug("adapter_idle: flags 0x%x, state 0x%hx, acr_flags 0x%x, acr_state 0x%hx\n",
                         vscsi->flags, vscsi->state, vscsi->phyp_acr_flags,
                         vscsi->phyp_acr_state);
        }

        pr_debug("Leaving adapter_idle: flags 0x%x, state 0x%hx, new_state 0x%x\n",
                 vscsi->flags, vscsi->state, vscsi->new_state);
}

/**
 * ibmvscsis_copy_crq_packet() - Copy CRQ Packet
 * @vscsi:      Pointer to our adapter structure
 * @cmd:        Pointer to command element to use to process the request
 * @crq:        Pointer to CRQ entry containing the request
 *
 * Copy the srp information unit from the hosted
 * partition using remote dma
 *
 * EXECUTION ENVIRONMENT:
 *      Interrupt, interrupt lock held
 */
static long ibmvscsis_copy_crq_packet(struct scsi_info *vscsi,
                                      struct ibmvscsis_cmd *cmd,
                                      struct viosrp_crq *crq)
{
        struct iu_entry *iue = cmd->iue;
        long rc = 0;
        u16 len;

        len = be16_to_cpu(crq->IU_length);
        if ((len > SRP_MAX_IU_LEN) || (len == 0)) {
                dev_err(&vscsi->dev, "copy_crq: Invalid len %d passed", len);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT, 0);
                return SRP_VIOLATION;
        }

        rc = h_copy_rdma(len, vscsi->dds.window[REMOTE].liobn,
                         be64_to_cpu(crq->IU_data_ptr),
                         vscsi->dds.window[LOCAL].liobn, iue->sbuf->dma);

        switch (rc) {
        case H_SUCCESS:
                cmd->init_time = mftb();
                iue->remote_token = crq->IU_data_ptr;
                iue->iu_len = len;
                pr_debug("copy_crq: ioba 0x%llx, init_time 0x%llx\n",
                         be64_to_cpu(crq->IU_data_ptr), cmd->init_time);
                break;
        case H_PERMISSION:
                if (connection_broken(vscsi))
                        ibmvscsis_post_disconnect(vscsi,
                                                  ERR_DISCONNECT_RECONNECT,
                                                  (RESPONSE_Q_DOWN |
                                                   CLIENT_FAILED));
                else
                        ibmvscsis_post_disconnect(vscsi,
                                                  ERR_DISCONNECT_RECONNECT, 0);

                dev_err(&vscsi->dev, "copy_crq: h_copy_rdma failed, rc %ld\n",
                        rc);
                break;
        case H_DEST_PARM:
        case H_SOURCE_PARM:
        default:
                dev_err(&vscsi->dev, "copy_crq: h_copy_rdma failed, rc %ld\n",
                        rc);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT, 0);
                break;
        }

        return rc;
}

/**
 * ibmvscsis_adapter_info - Service an Adapter Info MAnagement Data gram
 * @vscsi:      Pointer to our adapter structure
 * @iue:        Information Unit containing the Adapter Info MAD request
 *
 * EXECUTION ENVIRONMENT:
 *      Interrupt adapter lock is held
 */
static long ibmvscsis_adapter_info(struct scsi_info *vscsi,
                                   struct iu_entry *iue)
{
        struct viosrp_adapter_info *mad = &vio_iu(iue)->mad.adapter_info;
        struct mad_adapter_info_data *info;
        uint flag_bits = 0;
        dma_addr_t token;
        long rc;

        mad->common.status = cpu_to_be16(VIOSRP_MAD_SUCCESS);

        if (be16_to_cpu(mad->common.length) > sizeof(*info)) {
                mad->common.status = cpu_to_be16(VIOSRP_MAD_FAILED);
                return 0;
        }

        info = dma_alloc_coherent(&vscsi->dma_dev->dev, sizeof(*info), &token,
                                  GFP_ATOMIC);
        if (!info) {
                dev_err(&vscsi->dev, "bad dma_alloc_coherent %p\n",
                        iue->target);
                mad->common.status = cpu_to_be16(VIOSRP_MAD_FAILED);
                return 0;
        }

        /* Get remote info */
        rc = h_copy_rdma(be16_to_cpu(mad->common.length),
                         vscsi->dds.window[REMOTE].liobn,
                         be64_to_cpu(mad->buffer),
                         vscsi->dds.window[LOCAL].liobn, token);

        if (rc != H_SUCCESS) {
                if (rc == H_PERMISSION) {
                        if (connection_broken(vscsi))
                                flag_bits = (RESPONSE_Q_DOWN | CLIENT_FAILED);
                }
                pr_warn("adapter_info: h_copy_rdma from client failed, rc %ld\n",
                        rc);
                pr_debug("adapter_info: ioba 0x%llx, flags 0x%x, flag_bits 0x%x\n",
                         be64_to_cpu(mad->buffer), vscsi->flags, flag_bits);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT,
                                          flag_bits);
                goto free_dma;
        }

        /*
         * Copy client info, but ignore partition number, which we
         * already got from phyp - unless we failed to get it from
         * phyp (e.g. if we're running on a p5 system).
         */
        if (vscsi->client_data.partition_number == 0)
                vscsi->client_data.partition_number =
                        be32_to_cpu(info->partition_number);
        strncpy(vscsi->client_data.srp_version, info->srp_version,
                sizeof(vscsi->client_data.srp_version));
        strncpy(vscsi->client_data.partition_name, info->partition_name,
                sizeof(vscsi->client_data.partition_name));
        vscsi->client_data.mad_version = be32_to_cpu(info->mad_version);
        vscsi->client_data.os_type = be32_to_cpu(info->os_type);

        /* Copy our info */
        strncpy(info->srp_version, SRP_VERSION,
                sizeof(info->srp_version));
        strncpy(info->partition_name, vscsi->dds.partition_name,
                sizeof(info->partition_name));
        info->partition_number = cpu_to_be32(vscsi->dds.partition_num);
        info->mad_version = cpu_to_be32(MAD_VERSION_1);
        info->os_type = cpu_to_be32(LINUX);
        memset(&info->port_max_txu[0], 0, sizeof(info->port_max_txu));
        info->port_max_txu[0] = cpu_to_be32(MAX_TXU);

        dma_wmb();
        rc = h_copy_rdma(sizeof(*info), vscsi->dds.window[LOCAL].liobn,
                         token, vscsi->dds.window[REMOTE].liobn,
                         be64_to_cpu(mad->buffer));
        switch (rc) {
        case H_SUCCESS:
                break;

        case H_SOURCE_PARM:
        case H_DEST_PARM:
        case H_PERMISSION:
                if (connection_broken(vscsi))
                        flag_bits = (RESPONSE_Q_DOWN | CLIENT_FAILED);
        default:
                dev_err(&vscsi->dev, "adapter_info: h_copy_rdma to client failed, rc %ld\n",
                        rc);
                ibmvscsis_post_disconnect(vscsi,
                                          ERR_DISCONNECT_RECONNECT,
                                          flag_bits);
                break;
        }

free_dma:
        dma_free_coherent(&vscsi->dma_dev->dev, sizeof(*info), info, token);
        pr_debug("Leaving adapter_info, rc %ld\n", rc);

        return rc;
}

/**
 * ibmvscsis_cap_mad() - Service a Capabilities MAnagement Data gram
 * @vscsi:      Pointer to our adapter structure
 * @iue:        Information Unit containing the Capabilities MAD request
 *
 * NOTE: if you return an error from this routine you must be
 * disconnecting or you will cause a hang
 *
 * EXECUTION ENVIRONMENT:
 *      Interrupt called with adapter lock held
 */
static int ibmvscsis_cap_mad(struct scsi_info *vscsi, struct iu_entry *iue)
{
        struct viosrp_capabilities *mad = &vio_iu(iue)->mad.capabilities;
        struct capabilities *cap;
        struct mad_capability_common *common;
        dma_addr_t token;
        u16 olen, len, status, min_len, cap_len;
        u32 flag;
        uint flag_bits = 0;
        long rc = 0;

        olen = be16_to_cpu(mad->common.length);
        /*
         * struct capabilities hardcodes a couple capabilities after the
         * header, but the capabilities can actually be in any order.
         */
        min_len = offsetof(struct capabilities, migration);
        if ((olen < min_len) || (olen > PAGE_SIZE)) {
                pr_warn("cap_mad: invalid len %d\n", olen);
                mad->common.status = cpu_to_be16(VIOSRP_MAD_FAILED);
                return 0;
        }

        cap = dma_alloc_coherent(&vscsi->dma_dev->dev, olen, &token,
                                 GFP_ATOMIC);
        if (!cap) {
                dev_err(&vscsi->dev, "bad dma_alloc_coherent %p\n",
                        iue->target);
                mad->common.status = cpu_to_be16(VIOSRP_MAD_FAILED);
                return 0;
        }
        rc = h_copy_rdma(olen, vscsi->dds.window[REMOTE].liobn,
                         be64_to_cpu(mad->buffer),
                         vscsi->dds.window[LOCAL].liobn, token);
        if (rc == H_SUCCESS) {
                strncpy(cap->name, dev_name(&vscsi->dma_dev->dev),
                        SRP_MAX_LOC_LEN);

                len = olen - min_len;
                status = VIOSRP_MAD_SUCCESS;
                common = (struct mad_capability_common *)&cap->migration;

                while ((len > 0) && (status == VIOSRP_MAD_SUCCESS) && !rc) {
                        pr_debug("cap_mad: len left %hd, cap type %d, cap len %hd\n",
                                 len, be32_to_cpu(common->cap_type),
                                 be16_to_cpu(common->length));

                        cap_len = be16_to_cpu(common->length);
                        if (cap_len > len) {
                                dev_err(&vscsi->dev, "cap_mad: cap len mismatch with total len\n");
                                status = VIOSRP_MAD_FAILED;
                                break;
                        }

                        if (cap_len == 0) {
                                dev_err(&vscsi->dev, "cap_mad: cap len is 0\n");
                                status = VIOSRP_MAD_FAILED;
                                break;
                        }

                        switch (common->cap_type) {
                        default:
                                pr_debug("cap_mad: unsupported capability\n");
                                common->server_support = 0;
                                flag = cpu_to_be32((u32)CAP_LIST_SUPPORTED);
                                cap->flags &= ~flag;
                                break;
                        }

                        len = len - cap_len;
                        common = (struct mad_capability_common *)
                                ((char *)common + cap_len);
                }

                mad->common.status = cpu_to_be16(status);

                dma_wmb();
                rc = h_copy_rdma(olen, vscsi->dds.window[LOCAL].liobn, token,
                                 vscsi->dds.window[REMOTE].liobn,
                                 be64_to_cpu(mad->buffer));

                if (rc != H_SUCCESS) {
                        pr_debug("cap_mad: failed to copy to client, rc %ld\n",
                                 rc);

                        if (rc == H_PERMISSION) {
                                if (connection_broken(vscsi))
                                        flag_bits = (RESPONSE_Q_DOWN |
                                                     CLIENT_FAILED);
                        }

                        pr_warn("cap_mad: error copying data to client, rc %ld\n",
                                rc);
                        ibmvscsis_post_disconnect(vscsi,
                                                  ERR_DISCONNECT_RECONNECT,
                                                  flag_bits);
                }
        }

        dma_free_coherent(&vscsi->dma_dev->dev, olen, cap, token);

        pr_debug("Leaving cap_mad, rc %ld, client_cap 0x%x\n",
                 rc, vscsi->client_cap);

        return rc;
}

/**
 * ibmvscsis_process_mad() - Service a MAnagement Data gram
 * @vscsi:      Pointer to our adapter structure
 * @iue:        Information Unit containing the MAD request
 *
 * Must be called with interrupt lock held.
 */
static long ibmvscsis_process_mad(struct scsi_info *vscsi, struct iu_entry *iue)
{
        struct mad_common *mad = (struct mad_common *)&vio_iu(iue)->mad;
        struct viosrp_empty_iu *empty;
        long rc = ADAPT_SUCCESS;

        switch (be32_to_cpu(mad->type)) {
        case VIOSRP_EMPTY_IU_TYPE:
                empty = &vio_iu(iue)->mad.empty_iu;
                vscsi->empty_iu_id = be64_to_cpu(empty->buffer);
                vscsi->empty_iu_tag = be64_to_cpu(empty->common.tag);
                mad->status = cpu_to_be16(VIOSRP_MAD_SUCCESS);
                break;
        case VIOSRP_ADAPTER_INFO_TYPE:
                rc = ibmvscsis_adapter_info(vscsi, iue);
                break;
        case VIOSRP_CAPABILITIES_TYPE:
                rc = ibmvscsis_cap_mad(vscsi, iue);
                break;
        case VIOSRP_ENABLE_FAST_FAIL:
                if (vscsi->state == CONNECTED) {
                        vscsi->fast_fail = true;
                        mad->status = cpu_to_be16(VIOSRP_MAD_SUCCESS);
                } else {
                        pr_warn("fast fail mad sent after login\n");
                        mad->status = cpu_to_be16(VIOSRP_MAD_FAILED);
                }
                break;
        default:
                mad->status = cpu_to_be16(VIOSRP_MAD_NOT_SUPPORTED);
                break;
        }

        return rc;
}

/**
 * srp_snd_msg_failed() - Handle an error when sending a response
 * @vscsi:      Pointer to our adapter structure
 * @rc:         The return code from the h_send_crq command
 *
 * Must be called with interrupt lock held.
 */
static void srp_snd_msg_failed(struct scsi_info *vscsi, long rc)
{
        ktime_t kt;

        if (rc != H_DROPPED) {
                ibmvscsis_free_cmd_qs(vscsi);

                if (rc == H_CLOSED)
                        vscsi->flags |= CLIENT_FAILED;

                /* don't flag the same problem multiple times */
                if (!(vscsi->flags & RESPONSE_Q_DOWN)) {
                        vscsi->flags |= RESPONSE_Q_DOWN;
                        if (!(vscsi->state & (ERR_DISCONNECT |
                                              ERR_DISCONNECT_RECONNECT |
                                              ERR_DISCONNECTED | UNDEFINED))) {
                                dev_err(&vscsi->dev, "snd_msg_failed: setting RESPONSE_Q_DOWN, state 0x%hx, flags 0x%x, rc %ld\n",
                                        vscsi->state, vscsi->flags, rc);
                        }
                        ibmvscsis_post_disconnect(vscsi,
                                                  ERR_DISCONNECT_RECONNECT, 0);
                }
                return;
        }

        /*
         * The response queue is full.
         * If the server is processing SRP requests, i.e.
         * the client has successfully done an
         * SRP_LOGIN, then it will wait forever for room in
         * the queue.  However if the system admin
         * is attempting to unconfigure the server then one
         * or more children will be in a state where
         * they are being removed. So if there is even one
         * child being removed then the driver assumes
         * the system admin is attempting to break the
         * connection with the client and MAX_TIMER_POPS
         * is honored.
         */
        if ((vscsi->rsp_q_timer.timer_pops < MAX_TIMER_POPS) ||
            (vscsi->state == SRP_PROCESSING)) {
                pr_debug("snd_msg_failed: response queue full, flags 0x%x, timer started %d, pops %d\n",
                         vscsi->flags, (int)vscsi->rsp_q_timer.started,
                         vscsi->rsp_q_timer.timer_pops);

                /*
                 * Check if the timer is running; if it
                 * is not then start it up.
                 */
                if (!vscsi->rsp_q_timer.started) {
                        if (vscsi->rsp_q_timer.timer_pops <
                            MAX_TIMER_POPS) {
                                kt = WAIT_NANO_SECONDS;
                        } else {
                                /*
                                 * slide the timeslice if the maximum
                                 * timer pops have already happened
                                 */
                                kt = ktime_set(WAIT_SECONDS, 0);
                        }

                        vscsi->rsp_q_timer.started = true;
                        hrtimer_start(&vscsi->rsp_q_timer.timer, kt,
                                      HRTIMER_MODE_REL);
                }
        } else {
                /*
                 * TBD: Do we need to worry about this? Need to get
                 *      remove working.
                 */
                /*
                 * waited a long time and it appears the system admin
                 * is bring this driver down
                 */
                vscsi->flags |= RESPONSE_Q_DOWN;
                ibmvscsis_free_cmd_qs(vscsi);
                /*
                 * if the driver is already attempting to disconnect
                 * from the client and has already logged an error
                 * trace this event but don't put it in the error log
                 */
                if (!(vscsi->state & (ERR_DISCONNECT |
                                      ERR_DISCONNECT_RECONNECT |
                                      ERR_DISCONNECTED | UNDEFINED))) {
                        dev_err(&vscsi->dev, "client crq full too long\n");
                        ibmvscsis_post_disconnect(vscsi,
                                                  ERR_DISCONNECT_RECONNECT,
                                                  0);
                }
        }
}

/**
 * ibmvscsis_send_messages() - Send a Response
 * @vscsi:      Pointer to our adapter structure
 *
 * Send a response, first checking the waiting queue. Responses are
 * sent in order they are received. If the response cannot be sent,
 * because the client queue is full, it stays on the waiting queue.
 *
 * PRECONDITION:
 *      Called with interrupt lock held
 */
static void ibmvscsis_send_messages(struct scsi_info *vscsi)
{
        u64 msg_hi = 0;
        /* note do not attempt to access the IU_data_ptr with this pointer
         * it is not valid
         */
        struct viosrp_crq *crq = (struct viosrp_crq *)&msg_hi;
        struct ibmvscsis_cmd *cmd, *nxt;
        struct iu_entry *iue;
        long rc = ADAPT_SUCCESS;
        bool retry = false;

        if (!(vscsi->flags & RESPONSE_Q_DOWN)) {
                do {
                        retry = false;
                        list_for_each_entry_safe(cmd, nxt, &vscsi->waiting_rsp,
                                                 list) {
                                /*
                                 * Check to make sure abort cmd gets processed
                                 * prior to the abort tmr cmd
                                 */
                                if (cmd->flags & DELAY_SEND)
                                        continue;

                                if (cmd->abort_cmd) {
                                        retry = true;
                                        cmd->abort_cmd->flags &= ~(DELAY_SEND);
                                        cmd->abort_cmd = NULL;
                                }

                                /*
                                 * If CMD_T_ABORTED w/o CMD_T_TAS scenarios and
                                 * the case where LIO issued a
                                 * ABORT_TASK: Sending TMR_TASK_DOES_NOT_EXIST
                                 * case then we dont send a response, since it
                                 * was already done.
                                 */
                                if (cmd->se_cmd.transport_state & CMD_T_ABORTED &&
                                    !(cmd->se_cmd.transport_state & CMD_T_TAS)) {
                                        list_del(&cmd->list);
                                        ibmvscsis_free_cmd_resources(vscsi,
                                                                     cmd);
                                        /*
                                         * With a successfully aborted op
                                         * through LIO we want to increment the
                                         * the vscsi credit so that when we dont
                                         * send a rsp to the original scsi abort
                                         * op (h_send_crq), but the tm rsp to
                                         * the abort is sent, the credit is
                                         * correctly sent with the abort tm rsp.
                                         * We would need 1 for the abort tm rsp
                                         * and 1 credit for the aborted scsi op.
                                         * Thus we need to increment here.
                                         * Also we want to increment the credit
                                         * here because we want to make sure
                                         * cmd is actually released first
                                         * otherwise the client will think it
                                         * it can send a new cmd, and we could
                                         * find ourselves short of cmd elements.
                                         */
                                        vscsi->credit += 1;
                                } else {
                                        iue = cmd->iue;

                                        crq->valid = VALID_CMD_RESP_EL;
                                        crq->format = cmd->rsp.format;

                                        if (cmd->flags & CMD_FAST_FAIL)
                                                crq->status = VIOSRP_ADAPTER_FAIL;

                                        crq->IU_length = cpu_to_be16(cmd->rsp.len);

                                        rc = h_send_crq(vscsi->dma_dev->unit_address,
                                                        be64_to_cpu(msg_hi),
                                                        be64_to_cpu(cmd->rsp.tag));

                                        pr_debug("send_messages: cmd %p, tag 0x%llx, rc %ld\n",
                                                 cmd, be64_to_cpu(cmd->rsp.tag), rc);

                                        /* if all ok free up the command
                                         * element resources
                                         */
                                        if (rc == H_SUCCESS) {
                                                /* some movement has occurred */
                                                vscsi->rsp_q_timer.timer_pops = 0;
                                                list_del(&cmd->list);

                                                ibmvscsis_free_cmd_resources(vscsi,
                                                                             cmd);
                                        } else {
                                                srp_snd_msg_failed(vscsi, rc);
                                                break;
                                        }
                                }
                        }
                } while (retry);

                if (!rc) {
                        /*
                         * The timer could pop with the queue empty.  If
                         * this happens, rc will always indicate a
                         * success; clear the pop count.
                         */
                        vscsi->rsp_q_timer.timer_pops = 0;
                }
        } else {
                ibmvscsis_free_cmd_qs(vscsi);
        }
}

/* Called with intr lock held */
static void ibmvscsis_send_mad_resp(struct scsi_info *vscsi,
                                    struct ibmvscsis_cmd *cmd,
                                    struct viosrp_crq *crq)
{
        struct iu_entry *iue = cmd->iue;
        struct mad_common *mad = (struct mad_common *)&vio_iu(iue)->mad;
        uint flag_bits = 0;
        long rc;

        dma_wmb();
        rc = h_copy_rdma(sizeof(struct mad_common),
                         vscsi->dds.window[LOCAL].liobn, iue->sbuf->dma,
                         vscsi->dds.window[REMOTE].liobn,
                         be64_to_cpu(crq->IU_data_ptr));
        if (!rc) {
                cmd->rsp.format = VIOSRP_MAD_FORMAT;
                cmd->rsp.len = sizeof(struct mad_common);
                cmd->rsp.tag = mad->tag;
                list_add_tail(&cmd->list, &vscsi->waiting_rsp);
                ibmvscsis_send_messages(vscsi);
        } else {
                pr_debug("Error sending mad response, rc %ld\n", rc);
                if (rc == H_PERMISSION) {
                        if (connection_broken(vscsi))
                                flag_bits = (RESPONSE_Q_DOWN | CLIENT_FAILED);
                }
                dev_err(&vscsi->dev, "mad: failed to copy to client, rc %ld\n",
                        rc);

                ibmvscsis_free_cmd_resources(vscsi, cmd);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT,
                                          flag_bits);
        }
}

/**
 * ibmvscsis_mad() - Service a MAnagement Data gram.
 * @vscsi:      Pointer to our adapter structure
 * @crq:        Pointer to the CRQ entry containing the MAD request
 *
 * EXECUTION ENVIRONMENT:
 *      Interrupt, called with adapter lock held
 */
static long ibmvscsis_mad(struct scsi_info *vscsi, struct viosrp_crq *crq)
{
        struct iu_entry *iue;
        struct ibmvscsis_cmd *cmd;
        struct mad_common *mad;
        long rc = ADAPT_SUCCESS;

        switch (vscsi->state) {
                /*
                 * We have not exchanged Init Msgs yet, so this MAD was sent
                 * before the last Transport Event; client will not be
                 * expecting a response.
                 */
        case WAIT_CONNECTION:
                pr_debug("mad: in Wait Connection state, ignoring MAD, flags %d\n",
                         vscsi->flags);
                return ADAPT_SUCCESS;

        case SRP_PROCESSING:
        case CONNECTED:
                break;

                /*
                 * We should never get here while we're in these states.
                 * Just log an error and get out.
                 */
        case UNCONFIGURING:
        case WAIT_IDLE:
        case ERR_DISCONNECT:
        case ERR_DISCONNECT_RECONNECT:
        default:
                dev_err(&vscsi->dev, "mad: invalid adapter state %d for mad\n",
                        vscsi->state);
                return ADAPT_SUCCESS;
        }

        cmd = ibmvscsis_get_free_cmd(vscsi);
        if (!cmd) {
                dev_err(&vscsi->dev, "mad: failed to get cmd, debit %d\n",
                        vscsi->debit);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT, 0);
                return ERROR;
        }
        iue = cmd->iue;
        cmd->type = ADAPTER_MAD;

        rc = ibmvscsis_copy_crq_packet(vscsi, cmd, crq);
        if (!rc) {
                mad = (struct mad_common *)&vio_iu(iue)->mad;

                pr_debug("mad: type %d\n", be32_to_cpu(mad->type));

                rc = ibmvscsis_process_mad(vscsi, iue);

                pr_debug("mad: status %hd, rc %ld\n", be16_to_cpu(mad->status),
                         rc);

                if (!rc)
                        ibmvscsis_send_mad_resp(vscsi, cmd, crq);
        } else {
                ibmvscsis_free_cmd_resources(vscsi, cmd);
        }

        pr_debug("Leaving mad, rc %ld\n", rc);
        return rc;
}

/**
 * ibmvscsis_login_rsp() - Create/copy a login response notice to the client
 * @vscsi:      Pointer to our adapter structure
 * @cmd:        Pointer to the command for the SRP Login request
 *
 * EXECUTION ENVIRONMENT:
 *      Interrupt, interrupt lock held
 */
static long ibmvscsis_login_rsp(struct scsi_info *vscsi,
                                struct ibmvscsis_cmd *cmd)
{
        struct iu_entry *iue = cmd->iue;
        struct srp_login_rsp *rsp = &vio_iu(iue)->srp.login_rsp;
        struct format_code *fmt;
        uint flag_bits = 0;
        long rc = ADAPT_SUCCESS;

        memset(rsp, 0, sizeof(struct srp_login_rsp));

        rsp->opcode = SRP_LOGIN_RSP;
        rsp->req_lim_delta = cpu_to_be32(vscsi->request_limit);
        rsp->tag = cmd->rsp.tag;
        rsp->max_it_iu_len = cpu_to_be32(SRP_MAX_IU_LEN);
        rsp->max_ti_iu_len = cpu_to_be32(SRP_MAX_IU_LEN);
        fmt = (struct format_code *)&rsp->buf_fmt;
        fmt->buffers = SUPPORTED_FORMATS;
        vscsi->credit = 0;

        cmd->rsp.len = sizeof(struct srp_login_rsp);

        dma_wmb();
        rc = h_copy_rdma(cmd->rsp.len, vscsi->dds.window[LOCAL].liobn,
                         iue->sbuf->dma, vscsi->dds.window[REMOTE].liobn,
                         be64_to_cpu(iue->remote_token));

        switch (rc) {
        case H_SUCCESS:
                break;

        case H_PERMISSION:
                if (connection_broken(vscsi))
                        flag_bits = RESPONSE_Q_DOWN | CLIENT_FAILED;
                dev_err(&vscsi->dev, "login_rsp: error copying to client, rc %ld\n",
                        rc);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT,
                                          flag_bits);
                break;
        case H_SOURCE_PARM:
        case H_DEST_PARM:
        default:
                dev_err(&vscsi->dev, "login_rsp: error copying to client, rc %ld\n",
                        rc);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT, 0);
                break;
        }

        return rc;
}

/**
 * ibmvscsis_srp_login_rej() - Create/copy a login rejection notice to client
 * @vscsi:      Pointer to our adapter structure
 * @cmd:        Pointer to the command for the SRP Login request
 * @reason:     The reason the SRP Login is being rejected, per SRP protocol
 *
 * EXECUTION ENVIRONMENT:
 *      Interrupt, interrupt lock held
 */
static long ibmvscsis_srp_login_rej(struct scsi_info *vscsi,
                                    struct ibmvscsis_cmd *cmd, u32 reason)
{
        struct iu_entry *iue = cmd->iue;
        struct srp_login_rej *rej = &vio_iu(iue)->srp.login_rej;
        struct format_code *fmt;
        uint flag_bits = 0;
        long rc = ADAPT_SUCCESS;

        memset(rej, 0, sizeof(*rej));

        rej->opcode = SRP_LOGIN_REJ;
        rej->reason = cpu_to_be32(reason);
        rej->tag = cmd->rsp.tag;
        fmt = (struct format_code *)&rej->buf_fmt;
        fmt->buffers = SUPPORTED_FORMATS;

        cmd->rsp.len = sizeof(*rej);

        dma_wmb();
        rc = h_copy_rdma(cmd->rsp.len, vscsi->dds.window[LOCAL].liobn,
                         iue->sbuf->dma, vscsi->dds.window[REMOTE].liobn,
                         be64_to_cpu(iue->remote_token));

        switch (rc) {
        case H_SUCCESS:
                break;
        case H_PERMISSION:
                if (connection_broken(vscsi))
                        flag_bits = RESPONSE_Q_DOWN | CLIENT_FAILED;
                dev_err(&vscsi->dev, "login_rej: error copying to client, rc %ld\n",
                        rc);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT,
                                          flag_bits);
                break;
        case H_SOURCE_PARM:
        case H_DEST_PARM:
        default:
                dev_err(&vscsi->dev, "login_rej: error copying to client, rc %ld\n",
                        rc);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT, 0);
                break;
        }

        return rc;
}

static int ibmvscsis_make_nexus(struct ibmvscsis_tport *tport)
{
        char *name = tport->tport_name;
        struct ibmvscsis_nexus *nexus;
        int rc;

        if (tport->ibmv_nexus) {
                pr_debug("tport->ibmv_nexus already exists\n");
                return 0;
        }

        nexus = kzalloc(sizeof(*nexus), GFP_KERNEL);
        if (!nexus) {
                pr_err("Unable to allocate struct ibmvscsis_nexus\n");
                return -ENOMEM;
        }

        nexus->se_sess = target_alloc_session(&tport->se_tpg, 0, 0,
                                              TARGET_PROT_NORMAL, name, nexus,
                                              NULL);
        if (IS_ERR(nexus->se_sess)) {
                rc = PTR_ERR(nexus->se_sess);
                goto transport_init_fail;
        }

        tport->ibmv_nexus = nexus;

        return 0;

transport_init_fail:
        kfree(nexus);
        return rc;
}

static int ibmvscsis_drop_nexus(struct ibmvscsis_tport *tport)
{
        struct se_session *se_sess;
        struct ibmvscsis_nexus *nexus;

        nexus = tport->ibmv_nexus;
        if (!nexus)
                return -ENODEV;

        se_sess = nexus->se_sess;
        if (!se_sess)
                return -ENODEV;

        /*
         * Release the SCSI I_T Nexus to the emulated ibmvscsis Target Port
         */
        target_wait_for_sess_cmds(se_sess);
        transport_deregister_session_configfs(se_sess);
        transport_deregister_session(se_sess);
        tport->ibmv_nexus = NULL;
        kfree(nexus);

        return 0;
}

/**
 * ibmvscsis_srp_login() - Process an SRP Login Request
 * @vscsi:      Pointer to our adapter structure
 * @cmd:        Command element to use to process the SRP Login request
 * @crq:        Pointer to CRQ entry containing the SRP Login request
 *
 * EXECUTION ENVIRONMENT:
 *      Interrupt, called with interrupt lock held
 */
static long ibmvscsis_srp_login(struct scsi_info *vscsi,
                                struct ibmvscsis_cmd *cmd,
                                struct viosrp_crq *crq)
{
        struct iu_entry *iue = cmd->iue;
        struct srp_login_req *req = &vio_iu(iue)->srp.login_req;
        struct port_id {
                __be64 id_extension;
                __be64 io_guid;
        } *iport, *tport;
        struct format_code *fmt;
        u32 reason = 0x0;
        long rc = ADAPT_SUCCESS;

        iport = (struct port_id *)req->initiator_port_id;
        tport = (struct port_id *)req->target_port_id;
        fmt = (struct format_code *)&req->req_buf_fmt;
        if (be32_to_cpu(req->req_it_iu_len) > SRP_MAX_IU_LEN)
                reason = SRP_LOGIN_REJ_REQ_IT_IU_LENGTH_TOO_LARGE;
        else if (be32_to_cpu(req->req_it_iu_len) < 64)
                reason = SRP_LOGIN_REJ_UNABLE_ESTABLISH_CHANNEL;
        else if ((be64_to_cpu(iport->id_extension) > (MAX_NUM_PORTS - 1)) ||
                 (be64_to_cpu(tport->id_extension) > (MAX_NUM_PORTS - 1)))
                reason = SRP_LOGIN_REJ_UNABLE_ASSOCIATE_CHANNEL;
        else if (req->req_flags & SRP_MULTICHAN_MULTI)
                reason = SRP_LOGIN_REJ_MULTI_CHANNEL_UNSUPPORTED;
        else if (fmt->buffers & (~SUPPORTED_FORMATS))
                reason = SRP_LOGIN_REJ_UNSUPPORTED_DESCRIPTOR_FMT;
        else if ((fmt->buffers & SUPPORTED_FORMATS) == 0)
                reason = SRP_LOGIN_REJ_UNSUPPORTED_DESCRIPTOR_FMT;

        if (vscsi->state == SRP_PROCESSING)
                reason = SRP_LOGIN_REJ_CHANNEL_LIMIT_REACHED;

        rc = ibmvscsis_make_nexus(&vscsi->tport);
        if (rc)
                reason = SRP_LOGIN_REJ_UNABLE_ESTABLISH_CHANNEL;

        cmd->rsp.format = VIOSRP_SRP_FORMAT;
        cmd->rsp.tag = req->tag;

        pr_debug("srp_login: reason 0x%x\n", reason);

        if (reason)
                rc = ibmvscsis_srp_login_rej(vscsi, cmd, reason);
        else
                rc = ibmvscsis_login_rsp(vscsi, cmd);

        if (!rc) {
                if (!reason)
                        vscsi->state = SRP_PROCESSING;

                list_add_tail(&cmd->list, &vscsi->waiting_rsp);
                ibmvscsis_send_messages(vscsi);
        } else {
                ibmvscsis_free_cmd_resources(vscsi, cmd);
        }

        pr_debug("Leaving srp_login, rc %ld\n", rc);
        return rc;
}

/**
 * ibmvscsis_srp_i_logout() - Helper Function to close I_T Nexus
 * @vscsi:      Pointer to our adapter structure
 * @cmd:        Command element to use to process the Implicit Logout request
 * @crq:        Pointer to CRQ entry containing the Implicit Logout request
 *
 * Do the logic to close the I_T nexus.  This function may not
 * behave to specification.
 *
 * EXECUTION ENVIRONMENT:
 *      Interrupt, interrupt lock held
 */
static long ibmvscsis_srp_i_logout(struct scsi_info *vscsi,
                                   struct ibmvscsis_cmd *cmd,
                                   struct viosrp_crq *crq)
{
        struct iu_entry *iue = cmd->iue;
        struct srp_i_logout *log_out = &vio_iu(iue)->srp.i_logout;
        long rc = ADAPT_SUCCESS;

        if ((vscsi->debit > 0) || !list_empty(&vscsi->schedule_q) ||
            !list_empty(&vscsi->waiting_rsp)) {
                dev_err(&vscsi->dev, "i_logout: outstanding work\n");
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT, 0);
        } else {
                cmd->rsp.format = SRP_FORMAT;
                cmd->rsp.tag = log_out->tag;
                cmd->rsp.len = sizeof(struct mad_common);
                list_add_tail(&cmd->list, &vscsi->waiting_rsp);
                ibmvscsis_send_messages(vscsi);

                ibmvscsis_post_disconnect(vscsi, WAIT_IDLE, 0);
        }

        return rc;
}

/* Called with intr lock held */
static void ibmvscsis_srp_cmd(struct scsi_info *vscsi, struct viosrp_crq *crq)
{
        struct ibmvscsis_cmd *cmd;
        struct iu_entry *iue;
        struct srp_cmd *srp;
        struct srp_tsk_mgmt *tsk;
        long rc;

        if (vscsi->request_limit - vscsi->debit <= 0) {
                /* Client has exceeded request limit */
                dev_err(&vscsi->dev, "Client exceeded the request limit (%d), debit %d\n",
                        vscsi->request_limit, vscsi->debit);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT, 0);
                return;
        }

        cmd = ibmvscsis_get_free_cmd(vscsi);
        if (!cmd) {
                dev_err(&vscsi->dev, "srp_cmd failed to get cmd, debit %d\n",
                        vscsi->debit);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT, 0);
                return;
        }
        iue = cmd->iue;
        srp = &vio_iu(iue)->srp.cmd;

        rc = ibmvscsis_copy_crq_packet(vscsi, cmd, crq);
        if (rc) {
                ibmvscsis_free_cmd_resources(vscsi, cmd);
                return;
        }

        if (vscsi->state == SRP_PROCESSING) {
                switch (srp->opcode) {
                case SRP_LOGIN_REQ:
                        rc = ibmvscsis_srp_login(vscsi, cmd, crq);
                        break;

                case SRP_TSK_MGMT:
                        tsk = &vio_iu(iue)->srp.tsk_mgmt;
                        pr_debug("tsk_mgmt tag: %llu (0x%llx)\n", tsk->tag,
                                 tsk->tag);
                        cmd->rsp.tag = tsk->tag;
                        vscsi->debit += 1;
                        cmd->type = TASK_MANAGEMENT;
                        list_add_tail(&cmd->list, &vscsi->schedule_q);
                        queue_work(vscsi->work_q, &cmd->work);
                        break;

                case SRP_CMD:
                        pr_debug("srp_cmd tag: %llu (0x%llx)\n", srp->tag,
                                 srp->tag);
                        cmd->rsp.tag = srp->tag;
                        vscsi->debit += 1;
                        cmd->type = SCSI_CDB;
                        /*
                         * We want to keep track of work waiting for
                         * the workqueue.
                         */
                        list_add_tail(&cmd->list, &vscsi->schedule_q);
                        queue_work(vscsi->work_q, &cmd->work);
                        break;

                case SRP_I_LOGOUT:
                        rc = ibmvscsis_srp_i_logout(vscsi, cmd, crq);
                        break;

                case SRP_CRED_RSP:
                case SRP_AER_RSP:
                default:
                        ibmvscsis_free_cmd_resources(vscsi, cmd);
                        dev_err(&vscsi->dev, "invalid srp cmd, opcode %d\n",
                                (uint)srp->opcode);
                        ibmvscsis_post_disconnect(vscsi,
                                                  ERR_DISCONNECT_RECONNECT, 0);
                        break;
                }
        } else if (srp->opcode == SRP_LOGIN_REQ && vscsi->state == CONNECTED) {
                rc = ibmvscsis_srp_login(vscsi, cmd, crq);
        } else {
                ibmvscsis_free_cmd_resources(vscsi, cmd);
                dev_err(&vscsi->dev, "Invalid state %d to handle srp cmd\n",
                        vscsi->state);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT, 0);
        }
}

/**
 * ibmvscsis_ping_response() - Respond to a ping request
 * @vscsi:      Pointer to our adapter structure
 *
 * Let the client know that the server is alive and waiting on
 * its native I/O stack.
 * If any type of error occurs from the call to queue a ping
 * response then the client is either not accepting or receiving
 * interrupts.  Disconnect with an error.
 *
 * EXECUTION ENVIRONMENT:
 *      Interrupt, interrupt lock held
 */
static long ibmvscsis_ping_response(struct scsi_info *vscsi)
{
        struct viosrp_crq *crq;
        u64 buffer[2] = { 0, 0 };
        long rc;

        crq = (struct viosrp_crq *)&buffer;
        crq->valid = VALID_CMD_RESP_EL;
        crq->format = (u8)MESSAGE_IN_CRQ;
        crq->status = PING_RESPONSE;

        rc = h_send_crq(vscsi->dds.unit_id, cpu_to_be64(buffer[MSG_HI]),
                        cpu_to_be64(buffer[MSG_LOW]));

        switch (rc) {
        case H_SUCCESS:
                break;
        case H_CLOSED:
                vscsi->flags |= CLIENT_FAILED;
        case H_DROPPED:
                vscsi->flags |= RESPONSE_Q_DOWN;
        case H_REMOTE_PARM:
                dev_err(&vscsi->dev, "ping_response: h_send_crq failed, rc %ld\n",
                        rc);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT, 0);
                break;
        default:
                dev_err(&vscsi->dev, "ping_response: h_send_crq returned unknown rc %ld\n",
                        rc);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT, 0);
                break;
        }

        return rc;
}

/**
 * ibmvscsis_parse_command() - Parse an element taken from the cmd rsp queue.
 * @vscsi:      Pointer to our adapter structure
 * @crq:        Pointer to CRQ element containing the SRP request
 *
 * This function will return success if the command queue element is valid
 * and the srp iu or MAD request it pointed to was also valid.  That does
 * not mean that an error was not returned to the client.
 *
 * EXECUTION ENVIRONMENT:
 *      Interrupt, intr lock held
 */
static long ibmvscsis_parse_command(struct scsi_info *vscsi,
                                    struct viosrp_crq *crq)
{
        long rc = ADAPT_SUCCESS;

        switch (crq->valid) {
        case VALID_CMD_RESP_EL:
                switch (crq->format) {
                case OS400_FORMAT:
                case AIX_FORMAT:
                case LINUX_FORMAT:
                case MAD_FORMAT:
                        if (vscsi->flags & PROCESSING_MAD) {
                                rc = ERROR;
                                dev_err(&vscsi->dev, "parse_command: already processing mad\n");
                                ibmvscsis_post_disconnect(vscsi,
                                                       ERR_DISCONNECT_RECONNECT,
                                                       0);
                        } else {
                                vscsi->flags |= PROCESSING_MAD;
                                rc = ibmvscsis_mad(vscsi, crq);
                        }
                        break;

                case SRP_FORMAT:
                        ibmvscsis_srp_cmd(vscsi, crq);
                        break;

                case MESSAGE_IN_CRQ:
                        if (crq->status == PING)
                                ibmvscsis_ping_response(vscsi);
                        break;

                default:
                        dev_err(&vscsi->dev, "parse_command: invalid format %d\n",
                                (uint)crq->format);
                        ibmvscsis_post_disconnect(vscsi,
                                                  ERR_DISCONNECT_RECONNECT, 0);
                        break;
                }
                break;

        case VALID_TRANS_EVENT:
                rc = ibmvscsis_trans_event(vscsi, crq);
                break;

        case VALID_INIT_MSG:
                rc = ibmvscsis_init_msg(vscsi, crq);
                break;

        default:
                dev_err(&vscsi->dev, "parse_command: invalid valid field %d\n",
                        (uint)crq->valid);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT, 0);
                break;
        }

        /*
         * Return only what the interrupt handler cares
         * about. Most errors we keep right on trucking.
         */
        rc = vscsi->flags & SCHEDULE_DISCONNECT;

        return rc;
}

static int read_dma_window(struct scsi_info *vscsi)
{
        struct vio_dev *vdev = vscsi->dma_dev;
        const __be32 *dma_window;
        const __be32 *prop;

        /* TODO Using of_parse_dma_window would be better, but it doesn't give
         * a way to read multiple windows without already knowing the size of
         * a window or the number of windows.
         */
        dma_window = (const __be32 *)vio_get_attribute(vdev,
                                                       "ibm,my-dma-window",
                                                       NULL);
        if (!dma_window) {
                pr_err("Couldn't find ibm,my-dma-window property\n");
                return -1;
        }

        vscsi->dds.window[LOCAL].liobn = be32_to_cpu(*dma_window);
        dma_window++;

        prop = (const __be32 *)vio_get_attribute(vdev, "ibm,#dma-address-cells",
                                                 NULL);
        if (!prop) {
                pr_warn("Couldn't find ibm,#dma-address-cells property\n");
                dma_window++;
        } else {
                dma_window += be32_to_cpu(*prop);
        }

        prop = (const __be32 *)vio_get_attribute(vdev, "ibm,#dma-size-cells",
                                                 NULL);
        if (!prop) {
                pr_warn("Couldn't find ibm,#dma-size-cells property\n");
                dma_window++;
        } else {
                dma_window += be32_to_cpu(*prop);
        }

        /* dma_window should point to the second window now */
        vscsi->dds.window[REMOTE].liobn = be32_to_cpu(*dma_window);

        return 0;
}

static struct ibmvscsis_tport *ibmvscsis_lookup_port(const char *name)
{
        struct ibmvscsis_tport *tport = NULL;
        struct vio_dev *vdev;
        struct scsi_info *vscsi;

        spin_lock_bh(&ibmvscsis_dev_lock);
        list_for_each_entry(vscsi, &ibmvscsis_dev_list, list) {
                vdev = vscsi->dma_dev;
                if (!strcmp(dev_name(&vdev->dev), name)) {
                        tport = &vscsi->tport;
                        break;
                }
        }
        spin_unlock_bh(&ibmvscsis_dev_lock);

        return tport;
}

/**
 * ibmvscsis_parse_cmd() - Parse SRP Command
 * @vscsi:      Pointer to our adapter structure
 * @cmd:        Pointer to command element with SRP command
 *
 * Parse the srp command; if it is valid then submit it to tcm.
 * Note: The return code does not reflect the status of the SCSI CDB.
 *
 * EXECUTION ENVIRONMENT:
 *      Process level
 */
static void ibmvscsis_parse_cmd(struct scsi_info *vscsi,
                                struct ibmvscsis_cmd *cmd)
{
        struct iu_entry *iue = cmd->iue;
        struct srp_cmd *srp = (struct srp_cmd *)iue->sbuf->buf;
        struct ibmvscsis_nexus *nexus;
        u64 data_len = 0;
        enum dma_data_direction dir;
        int attr = 0;
        int rc = 0;

        nexus = vscsi->tport.ibmv_nexus;
        /*
         * additional length in bytes.  Note that the SRP spec says that
         * additional length is in 4-byte words, but technically the
         * additional length field is only the upper 6 bits of the byte.
         * The lower 2 bits are reserved.  If the lower 2 bits are 0 (as
         * all reserved fields should be), then interpreting the byte as
         * an int will yield the length in bytes.
         */
        if (srp->add_cdb_len & 0x03) {
                dev_err(&vscsi->dev, "parse_cmd: reserved bits set in IU\n");
                spin_lock_bh(&vscsi->intr_lock);
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT, 0);
                ibmvscsis_free_cmd_resources(vscsi, cmd);
                spin_unlock_bh(&vscsi->intr_lock);
                return;
        }

        if (srp_get_desc_table(srp, &dir, &data_len)) {
                dev_err(&vscsi->dev, "0x%llx: parsing SRP descriptor table failed.\n",
                        srp->tag);
                goto fail;
        }

        cmd->rsp.sol_not = srp->sol_not;

        switch (srp->task_attr) {
        case SRP_SIMPLE_TASK:
                attr = TCM_SIMPLE_TAG;
                break;
        case SRP_ORDERED_TASK:
                attr = TCM_ORDERED_TAG;
                break;
        case SRP_HEAD_TASK:
                attr = TCM_HEAD_TAG;
                break;
        case SRP_ACA_TASK:
                attr = TCM_ACA_TAG;
                break;
        default:
                dev_err(&vscsi->dev, "Invalid task attribute %d\n",
                        srp->task_attr);
                goto fail;
        }

        cmd->se_cmd.tag = be64_to_cpu(srp->tag);

        spin_lock_bh(&vscsi->intr_lock);
        list_add_tail(&cmd->list, &vscsi->active_q);
        spin_unlock_bh(&vscsi->intr_lock);

        srp->lun.scsi_lun[0] &= 0x3f;

        rc = target_submit_cmd(&cmd->se_cmd, nexus->se_sess, srp->cdb,
                               cmd->sense_buf, scsilun_to_int(&srp->lun),
                               data_len, attr, dir, 0);
        if (rc) {
                dev_err(&vscsi->dev, "target_submit_cmd failed, rc %d\n", rc);
                spin_lock_bh(&vscsi->intr_lock);
                list_del(&cmd->list);
                ibmvscsis_free_cmd_resources(vscsi, cmd);
                spin_unlock_bh(&vscsi->intr_lock);
                goto fail;
        }
        return;

fail:
        spin_lock_bh(&vscsi->intr_lock);
        ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT_RECONNECT, 0);
        spin_unlock_bh(&vscsi->intr_lock);
}

/**
 * ibmvscsis_parse_task() - Parse SRP Task Management Request
 * @vscsi:      Pointer to our adapter structure
 * @cmd:        Pointer to command element with SRP task management request
 *
 * Parse the srp task management request; if it is valid then submit it to tcm.
 * Note: The return code does not reflect the status of the task management
 * request.
 *
 * EXECUTION ENVIRONMENT:
 *      Processor level
 */
static void ibmvscsis_parse_task(struct scsi_info *vscsi,
                                 struct ibmvscsis_cmd *cmd)
{
        struct iu_entry *iue = cmd->iue;
        struct srp_tsk_mgmt *srp_tsk = &vio_iu(iue)->srp.tsk_mgmt;
        int tcm_type;
        u64 tag_to_abort = 0;
        int rc = 0;
        struct ibmvscsis_nexus *nexus;

        nexus = vscsi->tport.ibmv_nexus;

        cmd->rsp.sol_not = srp_tsk->sol_not;

        switch (srp_tsk->tsk_mgmt_func) {
        case SRP_TSK_ABORT_TASK:
                tcm_type = TMR_ABORT_TASK;
                tag_to_abort = be64_to_cpu(srp_tsk->task_tag);
                break;
        case SRP_TSK_ABORT_TASK_SET:
                tcm_type = TMR_ABORT_TASK_SET;
                break;
        case SRP_TSK_CLEAR_TASK_SET:
                tcm_type = TMR_CLEAR_TASK_SET;
                break;
        case SRP_TSK_LUN_RESET:
                tcm_type = TMR_LUN_RESET;
                break;
        case SRP_TSK_CLEAR_ACA:
                tcm_type = TMR_CLEAR_ACA;
                break;
        default:
                dev_err(&vscsi->dev, "unknown task mgmt func %d\n",
                        srp_tsk->tsk_mgmt_func);
                cmd->se_cmd.se_tmr_req->response =
                        TMR_TASK_MGMT_FUNCTION_NOT_SUPPORTED;
                rc = -1;
                break;
        }

        if (!rc) {
                cmd->se_cmd.tag = be64_to_cpu(srp_tsk->tag);

                spin_lock_bh(&vscsi->intr_lock);
                list_add_tail(&cmd->list, &vscsi->active_q);
                spin_unlock_bh(&vscsi->intr_lock);

                srp_tsk->lun.scsi_lun[0] &= 0x3f;

                pr_debug("calling submit_tmr, func %d\n",
                         srp_tsk->tsk_mgmt_func);
                rc = target_submit_tmr(&cmd->se_cmd, nexus->se_sess, NULL,
                                       scsilun_to_int(&srp_tsk->lun), srp_tsk,
                                       tcm_type, GFP_KERNEL, tag_to_abort, 0);
                if (rc) {
                        dev_err(&vscsi->dev, "target_submit_tmr failed, rc %d\n",
                                rc);
                        spin_lock_bh(&vscsi->intr_lock);
                        list_del(&cmd->list);
                        spin_unlock_bh(&vscsi->intr_lock);
                        cmd->se_cmd.se_tmr_req->response =
                                TMR_FUNCTION_REJECTED;
                }
        }

        if (rc)
                transport_send_check_condition_and_sense(&cmd->se_cmd, 0, 0);
}

static void ibmvscsis_scheduler(struct work_struct *work)
{
        struct ibmvscsis_cmd *cmd = container_of(work, struct ibmvscsis_cmd,
                                                 work);
        struct scsi_info *vscsi = cmd->adapter;

        spin_lock_bh(&vscsi->intr_lock);

        /* Remove from schedule_q */
        list_del(&cmd->list);

        /* Don't submit cmd if we're disconnecting */
        if (vscsi->flags & (SCHEDULE_DISCONNECT | DISCONNECT_SCHEDULED)) {
                ibmvscsis_free_cmd_resources(vscsi, cmd);

                /* ibmvscsis_disconnect might be waiting for us */
                if (list_empty(&vscsi->active_q) &&
                    list_empty(&vscsi->schedule_q) &&
                    (vscsi->flags & WAIT_FOR_IDLE)) {
                        vscsi->flags &= ~WAIT_FOR_IDLE;
                        complete(&vscsi->wait_idle);
                }

                spin_unlock_bh(&vscsi->intr_lock);
                return;
        }

        spin_unlock_bh(&vscsi->intr_lock);

        switch (cmd->type) {
        case SCSI_CDB:
                ibmvscsis_parse_cmd(vscsi, cmd);
                break;
        case TASK_MANAGEMENT:
                ibmvscsis_parse_task(vscsi, cmd);
                break;
        default:
                dev_err(&vscsi->dev, "scheduler, invalid cmd type %d\n",
                        cmd->type);
                spin_lock_bh(&vscsi->intr_lock);
                ibmvscsis_free_cmd_resources(vscsi, cmd);
                spin_unlock_bh(&vscsi->intr_lock);
                break;
        }
}

static int ibmvscsis_alloc_cmds(struct scsi_info *vscsi, int num)
{
        struct ibmvscsis_cmd *cmd;
        int i;

        INIT_LIST_HEAD(&vscsi->free_cmd);
        vscsi->cmd_pool = kcalloc(num, sizeof(struct ibmvscsis_cmd),
                                  GFP_KERNEL);
        if (!vscsi->cmd_pool)
                return -ENOMEM;

        for (i = 0, cmd = (struct ibmvscsis_cmd *)vscsi->cmd_pool; i < num;
             i++, cmd++) {
                cmd->abort_cmd = NULL;
                cmd->adapter = vscsi;
                INIT_WORK(&cmd->work, ibmvscsis_scheduler);
                list_add_tail(&cmd->list, &vscsi->free_cmd);
        }

        return 0;
}

static void ibmvscsis_free_cmds(struct scsi_info *vscsi)
{
        kfree(vscsi->cmd_pool);
        vscsi->cmd_pool = NULL;
        INIT_LIST_HEAD(&vscsi->free_cmd);
}

/**
 * ibmvscsis_service_wait_q() - Service Waiting Queue
 * @timer:      Pointer to timer which has expired
 *
 * This routine is called when the timer pops to service the waiting
 * queue. Elements on the queue have completed, their responses have been
 * copied to the client, but the client's response queue was full so
 * the queue message could not be sent. The routine grabs the proper locks
 * and calls send messages.
 *
 * EXECUTION ENVIRONMENT:
 *      called at interrupt level
 */
static enum hrtimer_restart ibmvscsis_service_wait_q(struct hrtimer *timer)
{
        struct timer_cb *p_timer = container_of(timer, struct timer_cb, timer);
        struct scsi_info *vscsi = container_of(p_timer, struct scsi_info,
                                               rsp_q_timer);

        spin_lock_bh(&vscsi->intr_lock);
        p_timer->timer_pops += 1;
        p_timer->started = false;
        ibmvscsis_send_messages(vscsi);
        spin_unlock_bh(&vscsi->intr_lock);

        return HRTIMER_NORESTART;
}

static long ibmvscsis_alloctimer(struct scsi_info *vscsi)
{
        struct timer_cb *p_timer;

        p_timer = &vscsi->rsp_q_timer;
        hrtimer_init(&p_timer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);

        p_timer->timer.function = ibmvscsis_service_wait_q;
        p_timer->started = false;
        p_timer->timer_pops = 0;

        return ADAPT_SUCCESS;
}

static void ibmvscsis_freetimer(struct scsi_info *vscsi)
{
        struct timer_cb *p_timer;

        p_timer = &vscsi->rsp_q_timer;

        (void)hrtimer_cancel(&p_timer->timer);

        p_timer->started = false;
        p_timer->timer_pops = 0;
}

static irqreturn_t ibmvscsis_interrupt(int dummy, void *data)
{
        struct scsi_info *vscsi = data;

        vio_disable_interrupts(vscsi->dma_dev);
        tasklet_schedule(&vscsi->work_task);

        return IRQ_HANDLED;
}

/**
 * ibmvscsis_enable_change_state() - Set new state based on enabled status
 * @vscsi:      Pointer to our adapter structure
 *
 * This function determines our new state now that we are enabled.  This
 * may involve sending an Init Complete message to the client.
 *
 * Must be called with interrupt lock held.
 */
static long ibmvscsis_enable_change_state(struct scsi_info *vscsi)
{
        int bytes;
        long rc = ADAPT_SUCCESS;

        bytes = vscsi->cmd_q.size * PAGE_SIZE;
        rc = h_reg_crq(vscsi->dds.unit_id, vscsi->cmd_q.crq_token, bytes);
        if (rc == H_CLOSED || rc == H_SUCCESS) {
                vscsi->state = WAIT_CONNECTION;
                rc = ibmvscsis_establish_new_q(vscsi);
        }

        if (rc != ADAPT_SUCCESS) {
                vscsi->state = ERR_DISCONNECTED;
                vscsi->flags |= RESPONSE_Q_DOWN;
        }

        return rc;
}

/**
 * ibmvscsis_create_command_q() - Create Command Queue
 * @vscsi:      Pointer to our adapter structure
 * @num_cmds:   Currently unused.  In the future, may be used to determine
 *              the size of the CRQ.
 *
 * Allocates memory for command queue maps remote memory into an ioba
 * initializes the command response queue
 *
 * EXECUTION ENVIRONMENT:
 *      Process level only
 */
static long ibmvscsis_create_command_q(struct scsi_info *vscsi, int num_cmds)
{
        int pages;
        struct vio_dev *vdev = vscsi->dma_dev;

        /* We might support multiple pages in the future, but just 1 for now */
        pages = 1;

        vscsi->cmd_q.size = pages;

        vscsi->cmd_q.base_addr =
                (struct viosrp_crq *)get_zeroed_page(GFP_KERNEL);
        if (!vscsi->cmd_q.base_addr)
                return -ENOMEM;

        vscsi->cmd_q.mask = ((uint)pages * CRQ_PER_PAGE) - 1;

        vscsi->cmd_q.crq_token = dma_map_single(&vdev->dev,
                                                vscsi->cmd_q.base_addr,
                                                PAGE_SIZE, DMA_BIDIRECTIONAL);
        if (dma_mapping_error(&vdev->dev, vscsi->cmd_q.crq_token)) {
                free_page((unsigned long)vscsi->cmd_q.base_addr);
                return -ENOMEM;
        }

        return 0;
}

/**
 * ibmvscsis_destroy_command_q - Destroy Command Queue
 * @vscsi:      Pointer to our adapter structure
 *
 * Releases memory for command queue and unmaps mapped remote memory.
 *
 * EXECUTION ENVIRONMENT:
 *      Process level only
 */
static void ibmvscsis_destroy_command_q(struct scsi_info *vscsi)
{
        dma_unmap_single(&vscsi->dma_dev->dev, vscsi->cmd_q.crq_token,
                         PAGE_SIZE, DMA_BIDIRECTIONAL);
        free_page((unsigned long)vscsi->cmd_q.base_addr);
        vscsi->cmd_q.base_addr = NULL;
        vscsi->state = NO_QUEUE;
}

static u8 ibmvscsis_fast_fail(struct scsi_info *vscsi,
                              struct ibmvscsis_cmd *cmd)
{
        struct iu_entry *iue = cmd->iue;
        struct se_cmd *se_cmd = &cmd->se_cmd;
        struct srp_cmd *srp = (struct srp_cmd *)iue->sbuf->buf;
        struct scsi_sense_hdr sshdr;
        u8 rc = se_cmd->scsi_status;

        if (vscsi->fast_fail && (READ_CMD(srp->cdb) || WRITE_CMD(srp->cdb)))
                if (scsi_normalize_sense(se_cmd->sense_buffer,
                                         se_cmd->scsi_sense_length, &sshdr))
                        if (sshdr.sense_key == HARDWARE_ERROR &&
                            (se_cmd->residual_count == 0 ||
                             se_cmd->residual_count == se_cmd->data_length)) {
                                rc = NO_SENSE;
                                cmd->flags |= CMD_FAST_FAIL;
                        }

        return rc;
}

/**
 * srp_build_response() - Build an SRP response buffer
 * @vscsi:      Pointer to our adapter structure
 * @cmd:        Pointer to command for which to send the response
 * @len_p:      Where to return the length of the IU response sent.  This
 *              is needed to construct the CRQ response.
 *
 * Build the SRP response buffer and copy it to the client's memory space.
 */
static long srp_build_response(struct scsi_info *vscsi,
                               struct ibmvscsis_cmd *cmd, uint *len_p)
{
        struct iu_entry *iue = cmd->iue;
        struct se_cmd *se_cmd = &cmd->se_cmd;
        struct srp_rsp *rsp;
        uint len;
        u32 rsp_code;
        char *data;
        u32 *tsk_status;
        long rc = ADAPT_SUCCESS;

        spin_lock_bh(&vscsi->intr_lock);

        rsp = &vio_iu(iue)->srp.rsp;
        len = sizeof(*rsp);
        memset(rsp, 0, len);
        data = rsp->data;

        rsp->opcode = SRP_RSP;

        rsp->req_lim_delta = cpu_to_be32(1 + vscsi->credit);
        rsp->tag = cmd->rsp.tag;
        rsp->flags = 0;

        if (cmd->type == SCSI_CDB) {
                rsp->status = ibmvscsis_fast_fail(vscsi, cmd);
                if (rsp->status) {
                        pr_debug("build_resp: cmd %p, scsi status %d\n", cmd,
                                 (int)rsp->status);
                        ibmvscsis_determine_resid(se_cmd, rsp);
                        if (se_cmd->scsi_sense_length && se_cmd->sense_buffer) {
                                rsp->sense_data_len =
                                        cpu_to_be32(se_cmd->scsi_sense_length);
                                rsp->flags |= SRP_RSP_FLAG_SNSVALID;
                                len += se_cmd->scsi_sense_length;
                                memcpy(data, se_cmd->sense_buffer,
                                       se_cmd->scsi_sense_length);
                        }
                        rsp->sol_not = (cmd->rsp.sol_not & UCSOLNT) >>
                                UCSOLNT_RESP_SHIFT;
                } else if (cmd->flags & CMD_FAST_FAIL) {
                        pr_debug("build_resp: cmd %p, fast fail\n", cmd);
                        rsp->sol_not = (cmd->rsp.sol_not & UCSOLNT) >>
                                UCSOLNT_RESP_SHIFT;
                } else {
                        rsp->sol_not = (cmd->rsp.sol_not & SCSOLNT) >>
                                SCSOLNT_RESP_SHIFT;
                }
        } else {
                /* this is task management */
                rsp->status = 0;
                rsp->resp_data_len = cpu_to_be32(4);
                rsp->flags |= SRP_RSP_FLAG_RSPVALID;

                switch (se_cmd->se_tmr_req->response) {
                case TMR_FUNCTION_COMPLETE:
                case TMR_TASK_DOES_NOT_EXIST:
                        rsp_code = SRP_TASK_MANAGEMENT_FUNCTION_COMPLETE;
                        rsp->sol_not = (cmd->rsp.sol_not & SCSOLNT) >>
                                SCSOLNT_RESP_SHIFT;
                        break;
                case TMR_TASK_MGMT_FUNCTION_NOT_SUPPORTED:
                case TMR_LUN_DOES_NOT_EXIST:
                        rsp_code = SRP_TASK_MANAGEMENT_FUNCTION_NOT_SUPPORTED;
                        rsp->sol_not = (cmd->rsp.sol_not & UCSOLNT) >>
                                UCSOLNT_RESP_SHIFT;
                        break;
                case TMR_FUNCTION_FAILED:
                case TMR_FUNCTION_REJECTED:
                default:
                        rsp_code = SRP_TASK_MANAGEMENT_FUNCTION_FAILED;
                        rsp->sol_not = (cmd->rsp.sol_not & UCSOLNT) >>
                                UCSOLNT_RESP_SHIFT;
                        break;
                }

                tsk_status = (u32 *)data;
                *tsk_status = cpu_to_be32(rsp_code);
                data = (char *)(tsk_status + 1);
                len += 4;
        }

        dma_wmb();
        rc = h_copy_rdma(len, vscsi->dds.window[LOCAL].liobn, iue->sbuf->dma,
                         vscsi->dds.window[REMOTE].liobn,
                         be64_to_cpu(iue->remote_token));

        switch (rc) {
        case H_SUCCESS:
                vscsi->credit = 0;
                *len_p = len;
                break;
        case H_PERMISSION:
                if (connection_broken(vscsi))
                        vscsi->flags |= RESPONSE_Q_DOWN | CLIENT_FAILED;

                dev_err(&vscsi->dev, "build_response: error copying to client, rc %ld, flags 0x%x, state 0x%hx\n",
                        rc, vscsi->flags, vscsi->state);
                break;
        case H_SOURCE_PARM:
        case H_DEST_PARM:
        default:
                dev_err(&vscsi->dev, "build_response: error copying to client, rc %ld\n",
                        rc);
                break;
        }

        spin_unlock_bh(&vscsi->intr_lock);

        return rc;
}

static int ibmvscsis_rdma(struct ibmvscsis_cmd *cmd, struct scatterlist *sg,
                          int nsg, struct srp_direct_buf *md, int nmd,
                          enum dma_data_direction dir, unsigned int bytes)
{
        struct iu_entry *iue = cmd->iue;
        struct srp_target *target = iue->target;
        struct scsi_info *vscsi = target->ldata;
        struct scatterlist *sgp;
        dma_addr_t client_ioba, server_ioba;
        ulong buf_len;
        ulong client_len, server_len;
        int md_idx;
        long tx_len;
        long rc = 0;

        if (bytes == 0)
                return 0;

        sgp = sg;
        client_len = 0;
        server_len = 0;
        md_idx = 0;
        tx_len = bytes;

        do {
                if (client_len == 0) {
                        if (md_idx >= nmd) {
                                dev_err(&vscsi->dev, "rdma: ran out of client memory descriptors\n");
                                rc = -EIO;
                                break;
                        }
                        client_ioba = be64_to_cpu(md[md_idx].va);
                        client_len = be32_to_cpu(md[md_idx].len);
                }
                if (server_len == 0) {
                        if (!sgp) {
                                dev_err(&vscsi->dev, "rdma: ran out of scatter/gather list\n");
                                rc = -EIO;
                                break;
                        }
                        server_ioba = sg_dma_address(sgp);
                        server_len = sg_dma_len(sgp);
                }

                buf_len = tx_len;

                if (buf_len > client_len)
                        buf_len = client_len;

                if (buf_len > server_len)
                        buf_len = server_len;

                if (buf_len > max_vdma_size)
                        buf_len = max_vdma_size;

                if (dir == DMA_TO_DEVICE) {
                        /* read from client */
                        rc = h_copy_rdma(buf_len,
                                         vscsi->dds.window[REMOTE].liobn,
                                         client_ioba,
                                         vscsi->dds.window[LOCAL].liobn,
                                         server_ioba);
                } else {
                        /* The h_copy_rdma will cause phyp, running in another
                         * partition, to read memory, so we need to make sure
                         * the data has been written out, hence these syncs.
                         */
                        /* ensure that everything is in memory */
                        isync();
                        /* ensure that memory has been made visible */
                        dma_wmb();
                        rc = h_copy_rdma(buf_len,
                                         vscsi->dds.window[LOCAL].liobn,
                                         server_ioba,
                                         vscsi->dds.window[REMOTE].liobn,
                                         client_ioba);
                }
                switch (rc) {
                case H_SUCCESS:
                        break;
                case H_PERMISSION:
                case H_SOURCE_PARM:
                case H_DEST_PARM:
                        if (connection_broken(vscsi)) {
                                spin_lock_bh(&vscsi->intr_lock);
                                vscsi->flags |=
                                        (RESPONSE_Q_DOWN | CLIENT_FAILED);
                                spin_unlock_bh(&vscsi->intr_lock);
                        }
                        dev_err(&vscsi->dev, "rdma: h_copy_rdma failed, rc %ld\n",
                                rc);
                        break;

                default:
                        dev_err(&vscsi->dev, "rdma: unknown error %ld from h_copy_rdma\n",
                                rc);
                        break;
                }

                if (!rc) {
                        tx_len -= buf_len;
                        if (tx_len) {
                                client_len -= buf_len;
                                if (client_len == 0)
                                        md_idx++;
                                else
                                        client_ioba += buf_len;

                                server_len -= buf_len;
                                if (server_len == 0)
                                        sgp = sg_next(sgp);
                                else
                                        server_ioba += buf_len;
                        } else {
                                break;
                        }
                }
        } while (!rc);

        return rc;
}

/**
 * ibmvscsis_handle_crq() - Handle CRQ
 * @data:       Pointer to our adapter structure
 *
 * Read the command elements from the command queue and copy the payloads
 * associated with the command elements to local memory and execute the
 * SRP requests.
 *
 * Note: this is an edge triggered interrupt. It can not be shared.
 */
static void ibmvscsis_handle_crq(unsigned long data)
{
        struct scsi_info *vscsi = (struct scsi_info *)data;
        struct viosrp_crq *crq;
        long rc;
        bool ack = true;
        volatile u8 valid;

        spin_lock_bh(&vscsi->intr_lock);

        pr_debug("got interrupt\n");

        /*
         * if we are in a path where we are waiting for all pending commands
         * to complete because we received a transport event and anything in
         * the command queue is for a new connection, do nothing
         */
        if (TARGET_STOP(vscsi)) {
                vio_enable_interrupts(vscsi->dma_dev);

                pr_debug("handle_crq, don't process: flags 0x%x, state 0x%hx\n",
                         vscsi->flags, vscsi->state);
                spin_unlock_bh(&vscsi->intr_lock);
                return;
        }

        rc = vscsi->flags & SCHEDULE_DISCONNECT;
        crq = vscsi->cmd_q.base_addr + vscsi->cmd_q.index;
        valid = crq->valid;
        dma_rmb();

        while (valid) {
                /*
                 * These are edege triggered interrupts. After dropping out of
                 * the while loop, the code must check for work since an
                 * interrupt could be lost, and an elment be left on the queue,
                 * hence the label.
                 */
cmd_work:
                vscsi->cmd_q.index =
                        (vscsi->cmd_q.index + 1) & vscsi->cmd_q.mask;

                if (!rc) {
                        rc = ibmvscsis_parse_command(vscsi, crq);
                } else {
                        if ((uint)crq->valid == VALID_TRANS_EVENT) {
                                /*
                                 * must service the transport layer events even
                                 * in an error state, dont break out until all
                                 * the consecutive transport events have been
                                 * processed
                                 */
                                rc = ibmvscsis_trans_event(vscsi, crq);
                        } else if (vscsi->flags & TRANS_EVENT) {
                                /*
                                 * if a transport event has occurred leave
                                 * everything but transport events on the queue
                                 *
                                 * need to decrement the queue index so we can
                                 * look at the element again
                                 */
                                if (vscsi->cmd_q.index)
                                        vscsi->cmd_q.index -= 1;
                                else
                                        /*
                                         * index is at 0 it just wrapped.
                                         * have it index last element in q
                                         */
                                        vscsi->cmd_q.index = vscsi->cmd_q.mask;
                                break;
                        }
                }

                crq->valid = INVALIDATE_CMD_RESP_EL;

                crq = vscsi->cmd_q.base_addr + vscsi->cmd_q.index;
                valid = crq->valid;
                dma_rmb();
        }

        if (!rc) {
                if (ack) {
                        vio_enable_interrupts(vscsi->dma_dev);
                        ack = false;
                        pr_debug("handle_crq, reenabling interrupts\n");
                }
                valid = crq->valid;
                dma_rmb();
                if (valid)
                        goto cmd_work;
        } else {
                pr_debug("handle_crq, error: flags 0x%x, state 0x%hx, crq index 0x%x\n",
                         vscsi->flags, vscsi->state, vscsi->cmd_q.index);
        }

        pr_debug("Leaving handle_crq: schedule_q empty %d, flags 0x%x, state 0x%hx\n",
                 (int)list_empty(&vscsi->schedule_q), vscsi->flags,
                 vscsi->state);

        spin_unlock_bh(&vscsi->intr_lock);
}

static int ibmvscsis_probe(struct vio_dev *vdev,
                           const struct vio_device_id *id)
{
        struct scsi_info *vscsi;
        int rc = 0;
        long hrc = 0;
        char wq_name[24];

        vscsi = kzalloc(sizeof(*vscsi), GFP_KERNEL);
        if (!vscsi) {
                rc = -ENOMEM;
                pr_err("probe: allocation of adapter failed\n");
                return rc;
        }

        vscsi->dma_dev = vdev;
        vscsi->dev = vdev->dev;
        INIT_LIST_HEAD(&vscsi->schedule_q);
        INIT_LIST_HEAD(&vscsi->waiting_rsp);
        INIT_LIST_HEAD(&vscsi->active_q);

        snprintf(vscsi->tport.tport_name, IBMVSCSIS_NAMELEN, "%s",
                 dev_name(&vdev->dev));

        pr_debug("probe tport_name: %s\n", vscsi->tport.tport_name);

        rc = read_dma_window(vscsi);
        if (rc)
                goto free_adapter;
        pr_debug("Probe: liobn 0x%x, riobn 0x%x\n",
                 vscsi->dds.window[LOCAL].liobn,
                 vscsi->dds.window[REMOTE].liobn);

        strcpy(vscsi->eye, "VSCSI ");
        strncat(vscsi->eye, vdev->name, MAX_EYE);

        vscsi->dds.unit_id = vdev->unit_address;
        strncpy(vscsi->dds.partition_name, partition_name,
                sizeof(vscsi->dds.partition_name));
        vscsi->dds.partition_num = partition_number;

        spin_lock_bh(&ibmvscsis_dev_lock);
        list_add_tail(&vscsi->list, &ibmvscsis_dev_list);
        spin_unlock_bh(&ibmvscsis_dev_lock);

        /*
         * TBD: How do we determine # of cmds to request?  Do we know how
         * many "children" we have?
         */
        vscsi->request_limit = INITIAL_SRP_LIMIT;
        rc = srp_target_alloc(&vscsi->target, &vdev->dev, vscsi->request_limit,
                              SRP_MAX_IU_LEN);
        if (rc)
                goto rem_list;

        vscsi->target.ldata = vscsi;

        rc = ibmvscsis_alloc_cmds(vscsi, vscsi->request_limit);
        if (rc) {
                dev_err(&vscsi->dev, "alloc_cmds failed, rc %d, num %d\n",
                        rc, vscsi->request_limit);
                goto free_target;
        }

        /*
         * Note: the lock is used in freeing timers, so must initialize
         * first so that ordering in case of error is correct.
         */
        spin_lock_init(&vscsi->intr_lock);

        rc = ibmvscsis_alloctimer(vscsi);
        if (rc) {
                dev_err(&vscsi->dev, "probe: alloctimer failed, rc %d\n", rc);
                goto free_cmds;
        }

        rc = ibmvscsis_create_command_q(vscsi, 256);
        if (rc) {
                dev_err(&vscsi->dev, "probe: create_command_q failed, rc %d\n",
                        rc);
                goto free_timer;
        }

        vscsi->map_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
        if (!vscsi->map_buf) {
                rc = -ENOMEM;
                dev_err(&vscsi->dev, "probe: allocating cmd buffer failed\n");
                goto destroy_queue;
        }

        vscsi->map_ioba = dma_map_single(&vdev->dev, vscsi->map_buf, PAGE_SIZE,
                                         DMA_BIDIRECTIONAL);
        if (dma_mapping_error(&vdev->dev, vscsi->map_ioba)) {
                rc = -ENOMEM;
                dev_err(&vscsi->dev, "probe: error mapping command buffer\n");
                goto free_buf;
        }

        hrc = h_vioctl(vscsi->dds.unit_id, H_GET_PARTNER_INFO,
                       (u64)vscsi->map_ioba | ((u64)PAGE_SIZE << 32), 0, 0, 0,
                       0);
        if (hrc == H_SUCCESS)
                vscsi->client_data.partition_number =
                        be64_to_cpu(*(u64 *)vscsi->map_buf);
        /*
         * We expect the VIOCTL to fail if we're configured as "any
         * client can connect" and the client isn't activated yet.
         * We'll make the call again when he sends an init msg.
         */
        pr_debug("probe hrc %ld, client partition num %d\n",
                 hrc, vscsi->client_data.partition_number);

        tasklet_init(&vscsi->work_task, ibmvscsis_handle_crq,
                     (unsigned long)vscsi);

        init_completion(&vscsi->wait_idle);
        init_completion(&vscsi->unconfig);

        snprintf(wq_name, 24, "ibmvscsis%s", dev_name(&vdev->dev));
        vscsi->work_q = create_workqueue(wq_name);
        if (!vscsi->work_q) {
                rc = -ENOMEM;
                dev_err(&vscsi->dev, "create_workqueue failed\n");
                goto unmap_buf;
        }

        rc = request_irq(vdev->irq, ibmvscsis_interrupt, 0, "ibmvscsis", vscsi);
        if (rc) {
                rc = -EPERM;
                dev_err(&vscsi->dev, "probe: request_irq failed, rc %d\n", rc);
                goto destroy_WQ;
        }

        vscsi->state = WAIT_ENABLED;

        dev_set_drvdata(&vdev->dev, vscsi);

        return 0;

destroy_WQ:
        destroy_workqueue(vscsi->work_q);
unmap_buf:
        dma_unmap_single(&vdev->dev, vscsi->map_ioba, PAGE_SIZE,
                         DMA_BIDIRECTIONAL);
free_buf:
        kfree(vscsi->map_buf);
destroy_queue:
        tasklet_kill(&vscsi->work_task);
        ibmvscsis_unregister_command_q(vscsi);
        ibmvscsis_destroy_command_q(vscsi);
free_timer:
        ibmvscsis_freetimer(vscsi);
free_cmds:
        ibmvscsis_free_cmds(vscsi);
free_target:
        srp_target_free(&vscsi->target);
rem_list:
        spin_lock_bh(&ibmvscsis_dev_lock);
        list_del(&vscsi->list);
        spin_unlock_bh(&ibmvscsis_dev_lock);
free_adapter:
        kfree(vscsi);

        return rc;
}

static int ibmvscsis_remove(struct vio_dev *vdev)
{
        struct scsi_info *vscsi = dev_get_drvdata(&vdev->dev);

        pr_debug("remove (%s)\n", dev_name(&vscsi->dma_dev->dev));

        spin_lock_bh(&vscsi->intr_lock);
        ibmvscsis_post_disconnect(vscsi, UNCONFIGURING, 0);
        vscsi->flags |= CFG_SLEEPING;
        spin_unlock_bh(&vscsi->intr_lock);
        wait_for_completion(&vscsi->unconfig);

        vio_disable_interrupts(vdev);
        free_irq(vdev->irq, vscsi);
        destroy_workqueue(vscsi->work_q);
        dma_unmap_single(&vdev->dev, vscsi->map_ioba, PAGE_SIZE,
                         DMA_BIDIRECTIONAL);
        kfree(vscsi->map_buf);
        tasklet_kill(&vscsi->work_task);
        ibmvscsis_destroy_command_q(vscsi);
        ibmvscsis_freetimer(vscsi);
        ibmvscsis_free_cmds(vscsi);
        srp_target_free(&vscsi->target);
        spin_lock_bh(&ibmvscsis_dev_lock);
        list_del(&vscsi->list);
        spin_unlock_bh(&ibmvscsis_dev_lock);
        kfree(vscsi);

        return 0;
}

static ssize_t system_id_show(struct device *dev,
                              struct device_attribute *attr, char *buf)
{
        return snprintf(buf, PAGE_SIZE, "%s\n", system_id);
}

static ssize_t partition_number_show(struct device *dev,
                                     struct device_attribute *attr, char *buf)
{
        return snprintf(buf, PAGE_SIZE, "%x\n", partition_number);
}

static ssize_t unit_address_show(struct device *dev,
                                 struct device_attribute *attr, char *buf)
{
        struct scsi_info *vscsi = container_of(dev, struct scsi_info, dev);

        return snprintf(buf, PAGE_SIZE, "%x\n", vscsi->dma_dev->unit_address);
}

static int ibmvscsis_get_system_info(void)
{
        struct device_node *rootdn, *vdevdn;
        const char *id, *model, *name;
        const uint *num;

        rootdn = of_find_node_by_path("/");
        if (!rootdn)
                return -ENOENT;

        model = of_get_property(rootdn, "model", NULL);
        id = of_get_property(rootdn, "system-id", NULL);
        if (model && id)
                snprintf(system_id, sizeof(system_id), "%s-%s", model, id);

        name = of_get_property(rootdn, "ibm,partition-name", NULL);
        if (name)
                strncpy(partition_name, name, sizeof(partition_name));

        num = of_get_property(rootdn, "ibm,partition-no", NULL);
        if (num)
                partition_number = of_read_number(num, 1);

        of_node_put(rootdn);

        vdevdn = of_find_node_by_path("/vdevice");
        if (vdevdn) {
                const uint *mvds;

                mvds = of_get_property(vdevdn, "ibm,max-virtual-dma-size",
                                       NULL);
                if (mvds)
                        max_vdma_size = *mvds;
                of_node_put(vdevdn);
        }

        return 0;
}

static char *ibmvscsis_get_fabric_name(void)
{
        return "ibmvscsis";
}

static char *ibmvscsis_get_fabric_wwn(struct se_portal_group *se_tpg)
{
        struct ibmvscsis_tport *tport =
                container_of(se_tpg, struct ibmvscsis_tport, se_tpg);

        return tport->tport_name;
}

static u16 ibmvscsis_get_tag(struct se_portal_group *se_tpg)
{
        struct ibmvscsis_tport *tport =
                container_of(se_tpg, struct ibmvscsis_tport, se_tpg);

        return tport->tport_tpgt;
}

static u32 ibmvscsis_get_default_depth(struct se_portal_group *se_tpg)
{
        return 1;
}

static int ibmvscsis_check_true(struct se_portal_group *se_tpg)
{
        return 1;
}

static int ibmvscsis_check_false(struct se_portal_group *se_tpg)
{
        return 0;
}

static u32 ibmvscsis_tpg_get_inst_index(struct se_portal_group *se_tpg)
{
        return 1;
}

static int ibmvscsis_check_stop_free(struct se_cmd *se_cmd)
{
        return target_put_sess_cmd(se_cmd);
}

static void ibmvscsis_release_cmd(struct se_cmd *se_cmd)
{
        struct ibmvscsis_cmd *cmd = container_of(se_cmd, struct ibmvscsis_cmd,
                                                 se_cmd);
        struct scsi_info *vscsi = cmd->adapter;

        spin_lock_bh(&vscsi->intr_lock);
        /* Remove from active_q */
        list_move_tail(&cmd->list, &vscsi->waiting_rsp);
        ibmvscsis_send_messages(vscsi);
        spin_unlock_bh(&vscsi->intr_lock);
}

static u32 ibmvscsis_sess_get_index(struct se_session *se_sess)
{
        return 0;
}

static int ibmvscsis_write_pending(struct se_cmd *se_cmd)
{
        struct ibmvscsis_cmd *cmd = container_of(se_cmd, struct ibmvscsis_cmd,
                                                 se_cmd);
        struct scsi_info *vscsi = cmd->adapter;
        struct iu_entry *iue = cmd->iue;
        int rc;

        /*
         * If CLIENT_FAILED OR RESPONSE_Q_DOWN, then just return success
         * since LIO can't do anything about it, and we dont want to
         * attempt an srp_transfer_data.
         */
        if ((vscsi->flags & (CLIENT_FAILED | RESPONSE_Q_DOWN))) {
                pr_err("write_pending failed since: %d\n", vscsi->flags);
                return 0;
        }

        rc = srp_transfer_data(cmd, &vio_iu(iue)->srp.cmd, ibmvscsis_rdma,
                               1, 1);
        if (rc) {
                pr_err("srp_transfer_data() failed: %d\n", rc);
                return -EIO;
        }
        /*
         * We now tell TCM to add this WRITE CDB directly into the TCM storage
         * object execution queue.
         */
        target_execute_cmd(se_cmd);
        return 0;
}

static int ibmvscsis_write_pending_status(struct se_cmd *se_cmd)
{
        return 0;
}

static void ibmvscsis_set_default_node_attrs(struct se_node_acl *nacl)
{
}

static int ibmvscsis_get_cmd_state(struct se_cmd *se_cmd)
{
        return 0;
}

static int ibmvscsis_queue_data_in(struct se_cmd *se_cmd)
{
        struct ibmvscsis_cmd *cmd = container_of(se_cmd, struct ibmvscsis_cmd,
                                                 se_cmd);
        struct iu_entry *iue = cmd->iue;
        struct scsi_info *vscsi = cmd->adapter;
        char *sd;
        uint len = 0;
        int rc;

        rc = srp_transfer_data(cmd, &vio_iu(iue)->srp.cmd, ibmvscsis_rdma, 1,
                               1);
        if (rc) {
                pr_err("srp_transfer_data failed: %d\n", rc);
                sd = se_cmd->sense_buffer;
                se_cmd->scsi_sense_length = 18;
                memset(se_cmd->sense_buffer, 0, se_cmd->scsi_sense_length);
                /* Logical Unit Communication Time-out asc/ascq = 0x0801 */
                scsi_build_sense_buffer(0, se_cmd->sense_buffer, MEDIUM_ERROR,
                                        0x08, 0x01);
        }

        srp_build_response(vscsi, cmd, &len);
        cmd->rsp.format = SRP_FORMAT;
        cmd->rsp.len = len;

        return 0;
}

static int ibmvscsis_queue_status(struct se_cmd *se_cmd)
{
        struct ibmvscsis_cmd *cmd = container_of(se_cmd, struct ibmvscsis_cmd,
                                                 se_cmd);
        struct scsi_info *vscsi = cmd->adapter;
        uint len;

        pr_debug("queue_status %p\n", se_cmd);

        srp_build_response(vscsi, cmd, &len);
        cmd->rsp.format = SRP_FORMAT;
        cmd->rsp.len = len;

        return 0;
}

static void ibmvscsis_queue_tm_rsp(struct se_cmd *se_cmd)
{
        struct ibmvscsis_cmd *cmd = container_of(se_cmd, struct ibmvscsis_cmd,
                                                 se_cmd);
        struct scsi_info *vscsi = cmd->adapter;
        struct ibmvscsis_cmd *cmd_itr;
        struct iu_entry *iue = iue = cmd->iue;
        struct srp_tsk_mgmt *srp_tsk = &vio_iu(iue)->srp.tsk_mgmt;
        u64 tag_to_abort = be64_to_cpu(srp_tsk->task_tag);
        uint len;

        pr_debug("queue_tm_rsp %p, status %d\n",
                 se_cmd, (int)se_cmd->se_tmr_req->response);

        if (srp_tsk->tsk_mgmt_func == SRP_TSK_ABORT_TASK &&
            cmd->se_cmd.se_tmr_req->response == TMR_TASK_DOES_NOT_EXIST) {
                spin_lock_bh(&vscsi->intr_lock);
                list_for_each_entry(cmd_itr, &vscsi->active_q, list) {
                        if (tag_to_abort == cmd_itr->se_cmd.tag) {
                                cmd_itr->abort_cmd = cmd;
                                cmd->flags |= DELAY_SEND;
                                break;
                        }
                }
                spin_unlock_bh(&vscsi->intr_lock);
        }

        srp_build_response(vscsi, cmd, &len);
        cmd->rsp.format = SRP_FORMAT;
        cmd->rsp.len = len;
}

static void ibmvscsis_aborted_task(struct se_cmd *se_cmd)
{
        pr_debug("ibmvscsis_aborted_task %p task_tag: %llu\n",
                 se_cmd, se_cmd->tag);
}

static struct se_wwn *ibmvscsis_make_tport(struct target_fabric_configfs *tf,
                                           struct config_group *group,
                                           const char *name)
{
        struct ibmvscsis_tport *tport;

        tport = ibmvscsis_lookup_port(name);
        if (tport) {
                tport->tport_proto_id = SCSI_PROTOCOL_SRP;
                pr_debug("make_tport(%s), pointer:%p, tport_id:%x\n",
                         name, tport, tport->tport_proto_id);
                return &tport->tport_wwn;
        }

        return ERR_PTR(-EINVAL);
}

static void ibmvscsis_drop_tport(struct se_wwn *wwn)
{
        struct ibmvscsis_tport *tport = container_of(wwn,
                                                     struct ibmvscsis_tport,
                                                     tport_wwn);

        pr_debug("drop_tport(%s)\n",
                 config_item_name(&tport->tport_wwn.wwn_group.cg_item));
}

static struct se_portal_group *ibmvscsis_make_tpg(struct se_wwn *wwn,
                                                  struct config_group *group,
                                                  const char *name)
{
        struct ibmvscsis_tport *tport =
                container_of(wwn, struct ibmvscsis_tport, tport_wwn);
        u16 tpgt;
        int rc;

        if (strstr(name, "tpgt_") != name)
                return ERR_PTR(-EINVAL);
        rc = kstrtou16(name + 5, 0, &tpgt);
        if (rc)
                return ERR_PTR(rc);
        tport->tport_tpgt = tpgt;

        tport->releasing = false;

        rc = core_tpg_register(&tport->tport_wwn, &tport->se_tpg,
                               tport->tport_proto_id);
        if (rc)
                return ERR_PTR(rc);

        return &tport->se_tpg;
}

static void ibmvscsis_drop_tpg(struct se_portal_group *se_tpg)
{
        struct ibmvscsis_tport *tport = container_of(se_tpg,
                                                     struct ibmvscsis_tport,
                                                     se_tpg);

        tport->releasing = true;
        tport->enabled = false;

        /*
         * Release the virtual I_T Nexus for this ibmvscsis TPG
         */
        ibmvscsis_drop_nexus(tport);
        /*
         * Deregister the se_tpg from TCM..
         */
        core_tpg_deregister(se_tpg);
}

static ssize_t ibmvscsis_wwn_version_show(struct config_item *item,
                                          char *page)
{
        return scnprintf(page, PAGE_SIZE, "%s\n", IBMVSCSIS_VERSION);
}
CONFIGFS_ATTR_RO(ibmvscsis_wwn_, version);

static struct configfs_attribute *ibmvscsis_wwn_attrs[] = {
        &ibmvscsis_wwn_attr_version,
        NULL,
};

static ssize_t ibmvscsis_tpg_enable_show(struct config_item *item,
                                         char *page)
{
        struct se_portal_group *se_tpg = to_tpg(item);
        struct ibmvscsis_tport *tport = container_of(se_tpg,
                                                     struct ibmvscsis_tport,
                                                     se_tpg);

        return snprintf(page, PAGE_SIZE, "%d\n", (tport->enabled) ? 1 : 0);
}

static ssize_t ibmvscsis_tpg_enable_store(struct config_item *item,
                                          const char *page, size_t count)
{
        struct se_portal_group *se_tpg = to_tpg(item);
        struct ibmvscsis_tport *tport = container_of(se_tpg,
                                                     struct ibmvscsis_tport,
                                                     se_tpg);
        struct scsi_info *vscsi = container_of(tport, struct scsi_info, tport);
        unsigned long tmp;
        int rc;
        long lrc;

        rc = kstrtoul(page, 0, &tmp);
        if (rc < 0) {
                pr_err("Unable to extract srpt_tpg_store_enable\n");
                return -EINVAL;
        }

        if ((tmp != 0) && (tmp != 1)) {
                pr_err("Illegal value for srpt_tpg_store_enable\n");
                return -EINVAL;
        }

        if (tmp) {
                spin_lock_bh(&vscsi->intr_lock);
                tport->enabled = true;
                lrc = ibmvscsis_enable_change_state(vscsi);
                if (lrc)
                        pr_err("enable_change_state failed, rc %ld state %d\n",
                               lrc, vscsi->state);
                spin_unlock_bh(&vscsi->intr_lock);
        } else {
                spin_lock_bh(&vscsi->intr_lock);
                tport->enabled = false;
                /* This simulates the server going down */
                ibmvscsis_post_disconnect(vscsi, ERR_DISCONNECT, 0);
                spin_unlock_bh(&vscsi->intr_lock);
        }

        pr_debug("tpg_enable_store, tmp %ld, state %d\n", tmp, vscsi->state);

        return count;
}
CONFIGFS_ATTR(ibmvscsis_tpg_, enable);

static struct configfs_attribute *ibmvscsis_tpg_attrs[] = {
        &ibmvscsis_tpg_attr_enable,
        NULL,
};

static const struct target_core_fabric_ops ibmvscsis_ops = {
        .module                         = THIS_MODULE,
        .name                           = "ibmvscsis",
        .max_data_sg_nents              = MAX_TXU / PAGE_SIZE,
        .get_fabric_name                = ibmvscsis_get_fabric_name,
        .tpg_get_wwn                    = ibmvscsis_get_fabric_wwn,
        .tpg_get_tag                    = ibmvscsis_get_tag,
        .tpg_get_default_depth          = ibmvscsis_get_default_depth,
        .tpg_check_demo_mode            = ibmvscsis_check_true,
        .tpg_check_demo_mode_cache      = ibmvscsis_check_true,
        .tpg_check_demo_mode_write_protect = ibmvscsis_check_false,
        .tpg_check_prod_mode_write_protect = ibmvscsis_check_false,
        .tpg_get_inst_index             = ibmvscsis_tpg_get_inst_index,
        .check_stop_free                = ibmvscsis_check_stop_free,
        .release_cmd                    = ibmvscsis_release_cmd,
        .sess_get_index                 = ibmvscsis_sess_get_index,
        .write_pending                  = ibmvscsis_write_pending,
        .write_pending_status           = ibmvscsis_write_pending_status,
        .set_default_node_attributes    = ibmvscsis_set_default_node_attrs,
        .get_cmd_state                  = ibmvscsis_get_cmd_state,
        .queue_data_in                  = ibmvscsis_queue_data_in,
        .queue_status                   = ibmvscsis_queue_status,
        .queue_tm_rsp                   = ibmvscsis_queue_tm_rsp,
        .aborted_task                   = ibmvscsis_aborted_task,
        /*
         * Setup function pointers for logic in target_core_fabric_configfs.c
         */
        .fabric_make_wwn                = ibmvscsis_make_tport,
        .fabric_drop_wwn                = ibmvscsis_drop_tport,
        .fabric_make_tpg                = ibmvscsis_make_tpg,
        .fabric_drop_tpg                = ibmvscsis_drop_tpg,

        .tfc_wwn_attrs                  = ibmvscsis_wwn_attrs,
        .tfc_tpg_base_attrs             = ibmvscsis_tpg_attrs,
};

static void ibmvscsis_dev_release(struct device *dev) {};

static struct device_attribute dev_attr_system_id =
        __ATTR(system_id, S_IRUGO, system_id_show, NULL);

static struct device_attribute dev_attr_partition_number =
        __ATTR(partition_number, S_IRUGO, partition_number_show, NULL);

static struct device_attribute dev_attr_unit_address =
        __ATTR(unit_address, S_IRUGO, unit_address_show, NULL);

static struct attribute *ibmvscsis_dev_attrs[] = {
        &dev_attr_system_id.attr,
        &dev_attr_partition_number.attr,
        &dev_attr_unit_address.attr,
};
ATTRIBUTE_GROUPS(ibmvscsis_dev);

static struct class ibmvscsis_class = {
        .name           = "ibmvscsis",
        .dev_release    = ibmvscsis_dev_release,
        .dev_groups     = ibmvscsis_dev_groups,
};

static struct vio_device_id ibmvscsis_device_table[] = {
        { "v-scsi-host", "IBM,v-scsi-host" },
        { "", "" }
};
MODULE_DEVICE_TABLE(vio, ibmvscsis_device_table);

static struct vio_driver ibmvscsis_driver = {
        .name = "ibmvscsis",
        .id_table = ibmvscsis_device_table,
        .probe = ibmvscsis_probe,
        .remove = ibmvscsis_remove,
};

/*
 * ibmvscsis_init() - Kernel Module initialization
 *
 * Note: vio_register_driver() registers callback functions, and at least one
 * of those callback functions calls TCM - Linux IO Target Subsystem, thus
 * the SCSI Target template must be registered before vio_register_driver()
 * is called.
 */
static int __init ibmvscsis_init(void)
{
        int rc = 0;

        rc = ibmvscsis_get_system_info();
        if (rc) {
                pr_err("rc %d from get_system_info\n", rc);
                goto out;
        }

        rc = class_register(&ibmvscsis_class);
        if (rc) {
                pr_err("failed class register\n");
                goto out;
        }

        rc = target_register_template(&ibmvscsis_ops);
        if (rc) {
                pr_err("rc %d from target_register_template\n", rc);
                goto unregister_class;
        }

        rc = vio_register_driver(&ibmvscsis_driver);
        if (rc) {
                pr_err("rc %d from vio_register_driver\n", rc);
                goto unregister_target;
        }

        return 0;

unregister_target:
        target_unregister_template(&ibmvscsis_ops);
unregister_class:
        class_unregister(&ibmvscsis_class);
out:
        return rc;
}

static void __exit ibmvscsis_exit(void)
{
        pr_info("Unregister IBM virtual SCSI host driver\n");
        vio_unregister_driver(&ibmvscsis_driver);
        target_unregister_template(&ibmvscsis_ops);
        class_unregister(&ibmvscsis_class);
}

MODULE_DESCRIPTION("IBMVSCSIS fabric driver");
MODULE_AUTHOR("Bryant G. Ly and Michael Cyr");
MODULE_LICENSE("GPL");
MODULE_VERSION(IBMVSCSIS_VERSION);
module_init(ibmvscsis_init);
module_exit(ibmvscsis_exit);