/*******************************************************************************
 *
 * This file contains the Linux/SCSI LLD virtual SCSI initiator driver
 * for emulated SAS initiator ports
 *
 * © Copyright 2011-2013 Datera, Inc.
 *
 * Licensed to the Linux Foundation under the General Public License (GPL) version 2.
 *
 * Author: Nicholas A. Bellinger <nab@risingtidesystems.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.
 ****************************************************************************/

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/configfs.h>
#include <scsi/scsi.h>
#include <scsi/scsi_tcq.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_cmnd.h>

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

#include "tcm_loop.h"

#define to_tcm_loop_hba(hba)    container_of(hba, struct tcm_loop_hba, dev)

/* Local pointer to allocated TCM configfs fabric module */
static struct target_fabric_configfs *tcm_loop_fabric_configfs;

static struct workqueue_struct *tcm_loop_workqueue;
static struct kmem_cache *tcm_loop_cmd_cache;

static int tcm_loop_hba_no_cnt;

static int tcm_loop_queue_status(struct se_cmd *se_cmd);

/*
 * Called from struct target_core_fabric_ops->check_stop_free()
 */
static int tcm_loop_check_stop_free(struct se_cmd *se_cmd)
{
        /*
         * Do not release struct se_cmd's containing a valid TMR
         * pointer.  These will be released directly in tcm_loop_device_reset()
         * with transport_generic_free_cmd().
         */
        if (se_cmd->se_cmd_flags & SCF_SCSI_TMR_CDB)
                return 0;
        /*
         * Release the struct se_cmd, which will make a callback to release
         * struct tcm_loop_cmd * in tcm_loop_deallocate_core_cmd()
         */
        transport_generic_free_cmd(se_cmd, 0);
        return 1;
}

static void tcm_loop_release_cmd(struct se_cmd *se_cmd)
{
        struct tcm_loop_cmd *tl_cmd = container_of(se_cmd,
                                struct tcm_loop_cmd, tl_se_cmd);

        kmem_cache_free(tcm_loop_cmd_cache, tl_cmd);
}

static int tcm_loop_show_info(struct seq_file *m, struct Scsi_Host *host)
{
        seq_printf(m, "tcm_loop_proc_info()\n");
        return 0;
}

static int tcm_loop_driver_probe(struct device *);
static int tcm_loop_driver_remove(struct device *);

static int pseudo_lld_bus_match(struct device *dev,
                                struct device_driver *dev_driver)
{
        return 1;
}

static struct bus_type tcm_loop_lld_bus = {
        .name                   = "tcm_loop_bus",
        .match                  = pseudo_lld_bus_match,
        .probe                  = tcm_loop_driver_probe,
        .remove                 = tcm_loop_driver_remove,
};

static struct device_driver tcm_loop_driverfs = {
        .name                   = "tcm_loop",
        .bus                    = &tcm_loop_lld_bus,
};
/*
 * Used with root_device_register() in tcm_loop_alloc_core_bus() below
 */
struct device *tcm_loop_primary;

static void tcm_loop_submission_work(struct work_struct *work)
{
        struct tcm_loop_cmd *tl_cmd =
                container_of(work, struct tcm_loop_cmd, work);
        struct se_cmd *se_cmd = &tl_cmd->tl_se_cmd;
        struct scsi_cmnd *sc = tl_cmd->sc;
        struct tcm_loop_nexus *tl_nexus;
        struct tcm_loop_hba *tl_hba;
        struct tcm_loop_tpg *tl_tpg;
        struct scatterlist *sgl_bidi = NULL;
        u32 sgl_bidi_count = 0, transfer_length;
        int rc;

        tl_hba = *(struct tcm_loop_hba **)shost_priv(sc->device->host);
        tl_tpg = &tl_hba->tl_hba_tpgs[sc->device->id];

        /*
         * Ensure that this tl_tpg reference from the incoming sc->device->id
         * has already been configured via tcm_loop_make_naa_tpg().
         */
        if (!tl_tpg->tl_hba) {
                set_host_byte(sc, DID_NO_CONNECT);
                goto out_done;
        }
        if (tl_tpg->tl_transport_status == TCM_TRANSPORT_OFFLINE) {
                set_host_byte(sc, DID_TRANSPORT_DISRUPTED);
                goto out_done;
        }
        tl_nexus = tl_tpg->tl_nexus;
        if (!tl_nexus) {
                scmd_printk(KERN_ERR, sc, "TCM_Loop I_T Nexus"
                                " does not exist\n");
                set_host_byte(sc, DID_ERROR);
                goto out_done;
        }
        if (scsi_bidi_cmnd(sc)) {
                struct scsi_data_buffer *sdb = scsi_in(sc);

                sgl_bidi = sdb->table.sgl;
                sgl_bidi_count = sdb->table.nents;
                se_cmd->se_cmd_flags |= SCF_BIDI;

        }

        transfer_length = scsi_transfer_length(sc);
        if (!scsi_prot_sg_count(sc) &&
            scsi_get_prot_op(sc) != SCSI_PROT_NORMAL) {
                se_cmd->prot_pto = true;
                /*
                 * loopback transport doesn't support
                 * WRITE_GENERATE, READ_STRIP protection
                 * information operations, go ahead unprotected.
                 */
                transfer_length = scsi_bufflen(sc);
        }

        rc = target_submit_cmd_map_sgls(se_cmd, tl_nexus->se_sess, sc->cmnd,
                        &tl_cmd->tl_sense_buf[0], tl_cmd->sc->device->lun,
                        transfer_length, TCM_SIMPLE_TAG,
                        sc->sc_data_direction, 0,
                        scsi_sglist(sc), scsi_sg_count(sc),
                        sgl_bidi, sgl_bidi_count,
                        scsi_prot_sglist(sc), scsi_prot_sg_count(sc));
        if (rc < 0) {
                set_host_byte(sc, DID_NO_CONNECT);
                goto out_done;
        }
        return;

out_done:
        kmem_cache_free(tcm_loop_cmd_cache, tl_cmd);
        sc->scsi_done(sc);
        return;
}

/*
 * ->queuecommand can be and usually is called from interrupt context, so
 * defer the actual submission to a workqueue.
 */
static int tcm_loop_queuecommand(struct Scsi_Host *sh, struct scsi_cmnd *sc)
{
        struct tcm_loop_cmd *tl_cmd;

        pr_debug("tcm_loop_queuecommand() %d:%d:%d:%llu got CDB: 0x%02x"
                " scsi_buf_len: %u\n", sc->device->host->host_no,
                sc->device->id, sc->device->channel, sc->device->lun,
                sc->cmnd[0], scsi_bufflen(sc));

        tl_cmd = kmem_cache_zalloc(tcm_loop_cmd_cache, GFP_ATOMIC);
        if (!tl_cmd) {
                pr_err("Unable to allocate struct tcm_loop_cmd\n");
                set_host_byte(sc, DID_ERROR);
                sc->scsi_done(sc);
                return 0;
        }

        tl_cmd->sc = sc;
        tl_cmd->sc_cmd_tag = sc->request->tag;
        INIT_WORK(&tl_cmd->work, tcm_loop_submission_work);
        queue_work(tcm_loop_workqueue, &tl_cmd->work);
        return 0;
}

/*
 * Called from SCSI EH process context to issue a LUN_RESET TMR
 * to struct scsi_device
 */
static int tcm_loop_issue_tmr(struct tcm_loop_tpg *tl_tpg,
                              int lun, int task, enum tcm_tmreq_table tmr)
{
        struct se_cmd *se_cmd = NULL;
        struct se_session *se_sess;
        struct se_portal_group *se_tpg;
        struct tcm_loop_nexus *tl_nexus;
        struct tcm_loop_cmd *tl_cmd = NULL;
        struct tcm_loop_tmr *tl_tmr = NULL;
        int ret = TMR_FUNCTION_FAILED, rc;

        /*
         * Locate the tl_nexus and se_sess pointers
         */
        tl_nexus = tl_tpg->tl_nexus;
        if (!tl_nexus) {
                pr_err("Unable to perform device reset without"
                                " active I_T Nexus\n");
                return ret;
        }

        tl_cmd = kmem_cache_zalloc(tcm_loop_cmd_cache, GFP_KERNEL);
        if (!tl_cmd) {
                pr_err("Unable to allocate memory for tl_cmd\n");
                return ret;
        }

        tl_tmr = kzalloc(sizeof(struct tcm_loop_tmr), GFP_KERNEL);
        if (!tl_tmr) {
                pr_err("Unable to allocate memory for tl_tmr\n");
                goto release;
        }
        init_waitqueue_head(&tl_tmr->tl_tmr_wait);

        se_cmd = &tl_cmd->tl_se_cmd;
        se_tpg = &tl_tpg->tl_se_tpg;
        se_sess = tl_tpg->tl_nexus->se_sess;
        /*
         * Initialize struct se_cmd descriptor from target_core_mod infrastructure
         */
        transport_init_se_cmd(se_cmd, se_tpg->se_tpg_tfo, se_sess, 0,
                                DMA_NONE, TCM_SIMPLE_TAG,
                                &tl_cmd->tl_sense_buf[0]);

        rc = core_tmr_alloc_req(se_cmd, tl_tmr, tmr, GFP_KERNEL);
        if (rc < 0)
                goto release;

        if (tmr == TMR_ABORT_TASK)
                se_cmd->se_tmr_req->ref_task_tag = task;

        /*
         * Locate the underlying TCM struct se_lun
         */
        if (transport_lookup_tmr_lun(se_cmd, lun) < 0) {
                ret = TMR_LUN_DOES_NOT_EXIST;
                goto release;
        }
        /*
         * Queue the TMR to TCM Core and sleep waiting for
         * tcm_loop_queue_tm_rsp() to wake us up.
         */
        transport_generic_handle_tmr(se_cmd);
        wait_event(tl_tmr->tl_tmr_wait, atomic_read(&tl_tmr->tmr_complete));
        /*
         * The TMR LUN_RESET has completed, check the response status and
         * then release allocations.
         */
        ret = se_cmd->se_tmr_req->response;
release:
        if (se_cmd)
                transport_generic_free_cmd(se_cmd, 1);
        else
                kmem_cache_free(tcm_loop_cmd_cache, tl_cmd);
        kfree(tl_tmr);
        return ret;
}

static int tcm_loop_abort_task(struct scsi_cmnd *sc)
{
        struct tcm_loop_hba *tl_hba;
        struct tcm_loop_tpg *tl_tpg;
        int ret = FAILED;

        /*
         * Locate the tcm_loop_hba_t pointer
         */
        tl_hba = *(struct tcm_loop_hba **)shost_priv(sc->device->host);
        tl_tpg = &tl_hba->tl_hba_tpgs[sc->device->id];
        ret = tcm_loop_issue_tmr(tl_tpg, sc->device->lun,
                                 sc->request->tag, TMR_ABORT_TASK);
        return (ret == TMR_FUNCTION_COMPLETE) ? SUCCESS : FAILED;
}

/*
 * Called from SCSI EH process context to issue a LUN_RESET TMR
 * to struct scsi_device
 */
static int tcm_loop_device_reset(struct scsi_cmnd *sc)
{
        struct tcm_loop_hba *tl_hba;
        struct tcm_loop_tpg *tl_tpg;
        int ret = FAILED;

        /*
         * Locate the tcm_loop_hba_t pointer
         */
        tl_hba = *(struct tcm_loop_hba **)shost_priv(sc->device->host);
        tl_tpg = &tl_hba->tl_hba_tpgs[sc->device->id];

        ret = tcm_loop_issue_tmr(tl_tpg, sc->device->lun,
                                 0, TMR_LUN_RESET);
        return (ret == TMR_FUNCTION_COMPLETE) ? SUCCESS : FAILED;
}

static int tcm_loop_target_reset(struct scsi_cmnd *sc)
{
        struct tcm_loop_hba *tl_hba;
        struct tcm_loop_tpg *tl_tpg;

        /*
         * Locate the tcm_loop_hba_t pointer
         */
        tl_hba = *(struct tcm_loop_hba **)shost_priv(sc->device->host);
        if (!tl_hba) {
                pr_err("Unable to perform device reset without"
                                " active I_T Nexus\n");
                return FAILED;
        }
        /*
         * Locate the tl_tpg pointer from TargetID in sc->device->id
         */
        tl_tpg = &tl_hba->tl_hba_tpgs[sc->device->id];
        if (tl_tpg) {
                tl_tpg->tl_transport_status = TCM_TRANSPORT_ONLINE;
                return SUCCESS;
        }
        return FAILED;
}

static int tcm_loop_slave_alloc(struct scsi_device *sd)
{
        set_bit(QUEUE_FLAG_BIDI, &sd->request_queue->queue_flags);
        return 0;
}

static struct scsi_host_template tcm_loop_driver_template = {
        .show_info              = tcm_loop_show_info,
        .proc_name              = "tcm_loopback",
        .name                   = "TCM_Loopback",
        .queuecommand           = tcm_loop_queuecommand,
        .change_queue_depth     = scsi_change_queue_depth,
        .eh_abort_handler = tcm_loop_abort_task,
        .eh_device_reset_handler = tcm_loop_device_reset,
        .eh_target_reset_handler = tcm_loop_target_reset,
        .can_queue              = 1024,
        .this_id                = -1,
        .sg_tablesize           = 256,
        .cmd_per_lun            = 1024,
        .max_sectors            = 0xFFFF,
        .use_clustering         = DISABLE_CLUSTERING,
        .slave_alloc            = tcm_loop_slave_alloc,
        .module                 = THIS_MODULE,
        .use_blk_tags           = 1,
        .track_queue_depth      = 1,
};

static int tcm_loop_driver_probe(struct device *dev)
{
        struct tcm_loop_hba *tl_hba;
        struct Scsi_Host *sh;
        int error, host_prot;

        tl_hba = to_tcm_loop_hba(dev);

        sh = scsi_host_alloc(&tcm_loop_driver_template,
                        sizeof(struct tcm_loop_hba));
        if (!sh) {
                pr_err("Unable to allocate struct scsi_host\n");
                return -ENODEV;
        }
        tl_hba->sh = sh;

        /*
         * Assign the struct tcm_loop_hba pointer to struct Scsi_Host->hostdata
         */
        *((struct tcm_loop_hba **)sh->hostdata) = tl_hba;
        /*
         * Setup single ID, Channel and LUN for now..
         */
        sh->max_id = 2;
        sh->max_lun = 0;
        sh->max_channel = 0;
        sh->max_cmd_len = TL_SCSI_MAX_CMD_LEN;

        host_prot = SHOST_DIF_TYPE1_PROTECTION | SHOST_DIF_TYPE2_PROTECTION |
                    SHOST_DIF_TYPE3_PROTECTION | SHOST_DIX_TYPE1_PROTECTION |
                    SHOST_DIX_TYPE2_PROTECTION | SHOST_DIX_TYPE3_PROTECTION;

        scsi_host_set_prot(sh, host_prot);
        scsi_host_set_guard(sh, SHOST_DIX_GUARD_CRC);

        error = scsi_add_host(sh, &tl_hba->dev);
        if (error) {
                pr_err("%s: scsi_add_host failed\n", __func__);
                scsi_host_put(sh);
                return -ENODEV;
        }
        return 0;
}

static int tcm_loop_driver_remove(struct device *dev)
{
        struct tcm_loop_hba *tl_hba;
        struct Scsi_Host *sh;

        tl_hba = to_tcm_loop_hba(dev);
        sh = tl_hba->sh;

        scsi_remove_host(sh);
        scsi_host_put(sh);
        return 0;
}

static void tcm_loop_release_adapter(struct device *dev)
{
        struct tcm_loop_hba *tl_hba = to_tcm_loop_hba(dev);

        kfree(tl_hba);
}

/*
 * Called from tcm_loop_make_scsi_hba() in tcm_loop_configfs.c
 */
static int tcm_loop_setup_hba_bus(struct tcm_loop_hba *tl_hba, int tcm_loop_host_id)
{
        int ret;

        tl_hba->dev.bus = &tcm_loop_lld_bus;
        tl_hba->dev.parent = tcm_loop_primary;
        tl_hba->dev.release = &tcm_loop_release_adapter;
        dev_set_name(&tl_hba->dev, "tcm_loop_adapter_%d", tcm_loop_host_id);

        ret = device_register(&tl_hba->dev);
        if (ret) {
                pr_err("device_register() failed for"
                                " tl_hba->dev: %d\n", ret);
                return -ENODEV;
        }

        return 0;
}

/*
 * Called from tcm_loop_fabric_init() in tcl_loop_fabric.c to load the emulated
 * tcm_loop SCSI bus.
 */
static int tcm_loop_alloc_core_bus(void)
{
        int ret;

        tcm_loop_primary = root_device_register("tcm_loop_0");
        if (IS_ERR(tcm_loop_primary)) {
                pr_err("Unable to allocate tcm_loop_primary\n");
                return PTR_ERR(tcm_loop_primary);
        }

        ret = bus_register(&tcm_loop_lld_bus);
        if (ret) {
                pr_err("bus_register() failed for tcm_loop_lld_bus\n");
                goto dev_unreg;
        }

        ret = driver_register(&tcm_loop_driverfs);
        if (ret) {
                pr_err("driver_register() failed for"
                                "tcm_loop_driverfs\n");
                goto bus_unreg;
        }

        pr_debug("Initialized TCM Loop Core Bus\n");
        return ret;

bus_unreg:
        bus_unregister(&tcm_loop_lld_bus);
dev_unreg:
        root_device_unregister(tcm_loop_primary);
        return ret;
}

static void tcm_loop_release_core_bus(void)
{
        driver_unregister(&tcm_loop_driverfs);
        bus_unregister(&tcm_loop_lld_bus);
        root_device_unregister(tcm_loop_primary);

        pr_debug("Releasing TCM Loop Core BUS\n");
}

static char *tcm_loop_get_fabric_name(void)
{
        return "loopback";
}

static u8 tcm_loop_get_fabric_proto_ident(struct se_portal_group *se_tpg)
{
        struct tcm_loop_tpg *tl_tpg = se_tpg->se_tpg_fabric_ptr;
        struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;
        /*
         * tl_proto_id is set at tcm_loop_configfs.c:tcm_loop_make_scsi_hba()
         * time based on the protocol dependent prefix of the passed configfs group.
         *
         * Based upon tl_proto_id, TCM_Loop emulates the requested fabric
         * ProtocolID using target_core_fabric_lib.c symbols.
         */
        switch (tl_hba->tl_proto_id) {
        case SCSI_PROTOCOL_SAS:
                return sas_get_fabric_proto_ident(se_tpg);
        case SCSI_PROTOCOL_FCP:
                return fc_get_fabric_proto_ident(se_tpg);
        case SCSI_PROTOCOL_ISCSI:
                return iscsi_get_fabric_proto_ident(se_tpg);
        default:
                pr_err("Unknown tl_proto_id: 0x%02x, using"
                        " SAS emulation\n", tl_hba->tl_proto_id);
                break;
        }

        return sas_get_fabric_proto_ident(se_tpg);
}

static char *tcm_loop_get_endpoint_wwn(struct se_portal_group *se_tpg)
{
        struct tcm_loop_tpg *tl_tpg = se_tpg->se_tpg_fabric_ptr;
        /*
         * Return the passed NAA identifier for the SAS Target Port
         */
        return &tl_tpg->tl_hba->tl_wwn_address[0];
}

static u16 tcm_loop_get_tag(struct se_portal_group *se_tpg)
{
        struct tcm_loop_tpg *tl_tpg = se_tpg->se_tpg_fabric_ptr;
        /*
         * This Tag is used when forming SCSI Name identifier in EVPD=1 0x83
         * to represent the SCSI Target Port.
         */
        return tl_tpg->tl_tpgt;
}

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

static u32 tcm_loop_get_pr_transport_id(
        struct se_portal_group *se_tpg,
        struct se_node_acl *se_nacl,
        struct t10_pr_registration *pr_reg,
        int *format_code,
        unsigned char *buf)
{
        struct tcm_loop_tpg *tl_tpg = se_tpg->se_tpg_fabric_ptr;
        struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;

        switch (tl_hba->tl_proto_id) {
        case SCSI_PROTOCOL_SAS:
                return sas_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
                                        format_code, buf);
        case SCSI_PROTOCOL_FCP:
                return fc_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
                                        format_code, buf);
        case SCSI_PROTOCOL_ISCSI:
                return iscsi_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
                                        format_code, buf);
        default:
                pr_err("Unknown tl_proto_id: 0x%02x, using"
                        " SAS emulation\n", tl_hba->tl_proto_id);
                break;
        }

        return sas_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
                        format_code, buf);
}

static u32 tcm_loop_get_pr_transport_id_len(
        struct se_portal_group *se_tpg,
        struct se_node_acl *se_nacl,
        struct t10_pr_registration *pr_reg,
        int *format_code)
{
        struct tcm_loop_tpg *tl_tpg = se_tpg->se_tpg_fabric_ptr;
        struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;

        switch (tl_hba->tl_proto_id) {
        case SCSI_PROTOCOL_SAS:
                return sas_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
                                        format_code);
        case SCSI_PROTOCOL_FCP:
                return fc_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
                                        format_code);
        case SCSI_PROTOCOL_ISCSI:
                return iscsi_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
                                        format_code);
        default:
                pr_err("Unknown tl_proto_id: 0x%02x, using"
                        " SAS emulation\n", tl_hba->tl_proto_id);
                break;
        }

        return sas_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
                        format_code);
}

/*
 * Used for handling SCSI fabric dependent TransportIDs in SPC-3 and above
 * Persistent Reservation SPEC_I_PT=1 and PROUT REGISTER_AND_MOVE operations.
 */
static char *tcm_loop_parse_pr_out_transport_id(
        struct se_portal_group *se_tpg,
        const char *buf,
        u32 *out_tid_len,
        char **port_nexus_ptr)
{
        struct tcm_loop_tpg *tl_tpg = se_tpg->se_tpg_fabric_ptr;
        struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;

        switch (tl_hba->tl_proto_id) {
        case SCSI_PROTOCOL_SAS:
                return sas_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
                                        port_nexus_ptr);
        case SCSI_PROTOCOL_FCP:
                return fc_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
                                        port_nexus_ptr);
        case SCSI_PROTOCOL_ISCSI:
                return iscsi_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
                                        port_nexus_ptr);
        default:
                pr_err("Unknown tl_proto_id: 0x%02x, using"
                        " SAS emulation\n", tl_hba->tl_proto_id);
                break;
        }

        return sas_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
                        port_nexus_ptr);
}

/*
 * Returning (1) here allows for target_core_mod struct se_node_acl to be generated
 * based upon the incoming fabric dependent SCSI Initiator Port
 */
static int tcm_loop_check_demo_mode(struct se_portal_group *se_tpg)
{
        return 1;
}

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

/*
 * Allow I_T Nexus full READ-WRITE access without explict Initiator Node ACLs for
 * local virtual Linux/SCSI LLD passthrough into VM hypervisor guest
 */
static int tcm_loop_check_demo_mode_write_protect(struct se_portal_group *se_tpg)
{
        return 0;
}

/*
 * Because TCM_Loop does not use explict ACLs and MappedLUNs, this will
 * never be called for TCM_Loop by target_core_fabric_configfs.c code.
 * It has been added here as a nop for target_fabric_tf_ops_check()
 */
static int tcm_loop_check_prod_mode_write_protect(struct se_portal_group *se_tpg)
{
        return 0;
}

static struct se_node_acl *tcm_loop_tpg_alloc_fabric_acl(
        struct se_portal_group *se_tpg)
{
        struct tcm_loop_nacl *tl_nacl;

        tl_nacl = kzalloc(sizeof(struct tcm_loop_nacl), GFP_KERNEL);
        if (!tl_nacl) {
                pr_err("Unable to allocate struct tcm_loop_nacl\n");
                return NULL;
        }

        return &tl_nacl->se_node_acl;
}

static void tcm_loop_tpg_release_fabric_acl(
        struct se_portal_group *se_tpg,
        struct se_node_acl *se_nacl)
{
        struct tcm_loop_nacl *tl_nacl = container_of(se_nacl,
                                struct tcm_loop_nacl, se_node_acl);

        kfree(tl_nacl);
}

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

static u32 tcm_loop_sess_get_index(struct se_session *se_sess)
{
        return 1;
}

static void tcm_loop_set_default_node_attributes(struct se_node_acl *se_acl)
{
        return;
}

static u32 tcm_loop_get_task_tag(struct se_cmd *se_cmd)
{
        struct tcm_loop_cmd *tl_cmd = container_of(se_cmd,
                        struct tcm_loop_cmd, tl_se_cmd);

        return tl_cmd->sc_cmd_tag;
}

static int tcm_loop_get_cmd_state(struct se_cmd *se_cmd)
{
        struct tcm_loop_cmd *tl_cmd = container_of(se_cmd,
                        struct tcm_loop_cmd, tl_se_cmd);

        return tl_cmd->sc_cmd_state;
}

static int tcm_loop_shutdown_session(struct se_session *se_sess)
{
        return 0;
}

static void tcm_loop_close_session(struct se_session *se_sess)
{
        return;
};

static int tcm_loop_write_pending(struct se_cmd *se_cmd)
{
        /*
         * Since Linux/SCSI has already sent down a struct scsi_cmnd
         * sc->sc_data_direction of DMA_TO_DEVICE with struct scatterlist array
         * memory, and memory has already been mapped to struct se_cmd->t_mem_list
         * format with transport_generic_map_mem_to_cmd().
         *
         * 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 tcm_loop_write_pending_status(struct se_cmd *se_cmd)
{
        return 0;
}

static int tcm_loop_queue_data_in(struct se_cmd *se_cmd)
{
        struct tcm_loop_cmd *tl_cmd = container_of(se_cmd,
                                struct tcm_loop_cmd, tl_se_cmd);
        struct scsi_cmnd *sc = tl_cmd->sc;

        pr_debug("tcm_loop_queue_data_in() called for scsi_cmnd: %p"
                     " cdb: 0x%02x\n", sc, sc->cmnd[0]);

        sc->result = SAM_STAT_GOOD;
        set_host_byte(sc, DID_OK);
        if ((se_cmd->se_cmd_flags & SCF_OVERFLOW_BIT) ||
            (se_cmd->se_cmd_flags & SCF_UNDERFLOW_BIT))
                scsi_set_resid(sc, se_cmd->residual_count);
        sc->scsi_done(sc);
        return 0;
}

static int tcm_loop_queue_status(struct se_cmd *se_cmd)
{
        struct tcm_loop_cmd *tl_cmd = container_of(se_cmd,
                                struct tcm_loop_cmd, tl_se_cmd);
        struct scsi_cmnd *sc = tl_cmd->sc;

        pr_debug("tcm_loop_queue_status() called for scsi_cmnd: %p"
                        " cdb: 0x%02x\n", sc, sc->cmnd[0]);

        if (se_cmd->sense_buffer &&
           ((se_cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE) ||
            (se_cmd->se_cmd_flags & SCF_EMULATED_TASK_SENSE))) {

                memcpy(sc->sense_buffer, se_cmd->sense_buffer,
                                SCSI_SENSE_BUFFERSIZE);
                sc->result = SAM_STAT_CHECK_CONDITION;
                set_driver_byte(sc, DRIVER_SENSE);
        } else
                sc->result = se_cmd->scsi_status;

        set_host_byte(sc, DID_OK);
        if ((se_cmd->se_cmd_flags & SCF_OVERFLOW_BIT) ||
            (se_cmd->se_cmd_flags & SCF_UNDERFLOW_BIT))
                scsi_set_resid(sc, se_cmd->residual_count);
        sc->scsi_done(sc);
        return 0;
}

static void tcm_loop_queue_tm_rsp(struct se_cmd *se_cmd)
{
        struct se_tmr_req *se_tmr = se_cmd->se_tmr_req;
        struct tcm_loop_tmr *tl_tmr = se_tmr->fabric_tmr_ptr;
        /*
         * The SCSI EH thread will be sleeping on se_tmr->tl_tmr_wait, go ahead
         * and wake up the wait_queue_head_t in tcm_loop_device_reset()
         */
        atomic_set(&tl_tmr->tmr_complete, 1);
        wake_up(&tl_tmr->tl_tmr_wait);
}

static void tcm_loop_aborted_task(struct se_cmd *se_cmd)
{
        return;
}

static char *tcm_loop_dump_proto_id(struct tcm_loop_hba *tl_hba)
{
        switch (tl_hba->tl_proto_id) {
        case SCSI_PROTOCOL_SAS:
                return "SAS";
        case SCSI_PROTOCOL_FCP:
                return "FCP";
        case SCSI_PROTOCOL_ISCSI:
                return "iSCSI";
        default:
                break;
        }

        return "Unknown";
}

/* Start items for tcm_loop_port_cit */

static int tcm_loop_port_link(
        struct se_portal_group *se_tpg,
        struct se_lun *lun)
{
        struct tcm_loop_tpg *tl_tpg = container_of(se_tpg,
                                struct tcm_loop_tpg, tl_se_tpg);
        struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;

        atomic_inc_mb(&tl_tpg->tl_tpg_port_count);
        /*
         * Add Linux/SCSI struct scsi_device by HCTL
         */
        scsi_add_device(tl_hba->sh, 0, tl_tpg->tl_tpgt, lun->unpacked_lun);

        pr_debug("TCM_Loop_ConfigFS: Port Link Successful\n");
        return 0;
}

static void tcm_loop_port_unlink(
        struct se_portal_group *se_tpg,
        struct se_lun *se_lun)
{
        struct scsi_device *sd;
        struct tcm_loop_hba *tl_hba;
        struct tcm_loop_tpg *tl_tpg;

        tl_tpg = container_of(se_tpg, struct tcm_loop_tpg, tl_se_tpg);
        tl_hba = tl_tpg->tl_hba;

        sd = scsi_device_lookup(tl_hba->sh, 0, tl_tpg->tl_tpgt,
                                se_lun->unpacked_lun);
        if (!sd) {
                pr_err("Unable to locate struct scsi_device for %d:%d:"
                        "%d\n", 0, tl_tpg->tl_tpgt, se_lun->unpacked_lun);
                return;
        }
        /*
         * Remove Linux/SCSI struct scsi_device by HCTL
         */
        scsi_remove_device(sd);
        scsi_device_put(sd);

        atomic_dec_mb(&tl_tpg->tl_tpg_port_count);

        pr_debug("TCM_Loop_ConfigFS: Port Unlink Successful\n");
}

/* End items for tcm_loop_port_cit */

/* Start items for tcm_loop_nexus_cit */

static int tcm_loop_make_nexus(
        struct tcm_loop_tpg *tl_tpg,
        const char *name)
{
        struct se_portal_group *se_tpg;
        struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;
        struct tcm_loop_nexus *tl_nexus;
        int ret = -ENOMEM;

        if (tl_tpg->tl_nexus) {
                pr_debug("tl_tpg->tl_nexus already exists\n");
                return -EEXIST;
        }
        se_tpg = &tl_tpg->tl_se_tpg;

        tl_nexus = kzalloc(sizeof(struct tcm_loop_nexus), GFP_KERNEL);
        if (!tl_nexus) {
                pr_err("Unable to allocate struct tcm_loop_nexus\n");
                return -ENOMEM;
        }
        /*
         * Initialize the struct se_session pointer
         */
        tl_nexus->se_sess = transport_init_session(TARGET_PROT_ALL);
        if (IS_ERR(tl_nexus->se_sess)) {
                ret = PTR_ERR(tl_nexus->se_sess);
                goto out;
        }
        /*
         * Since we are running in 'demo mode' this call with generate a
         * struct se_node_acl for the tcm_loop struct se_portal_group with the SCSI
         * Initiator port name of the passed configfs group 'name'.
         */
        tl_nexus->se_sess->se_node_acl = core_tpg_check_initiator_node_acl(
                                se_tpg, (unsigned char *)name);
        if (!tl_nexus->se_sess->se_node_acl) {
                transport_free_session(tl_nexus->se_sess);
                goto out;
        }
        /* Now, register the SAS I_T Nexus as active. */
        transport_register_session(se_tpg, tl_nexus->se_sess->se_node_acl,
                        tl_nexus->se_sess, tl_nexus);
        tl_tpg->tl_nexus = tl_nexus;
        pr_debug("TCM_Loop_ConfigFS: Established I_T Nexus to emulated"
                " %s Initiator Port: %s\n", tcm_loop_dump_proto_id(tl_hba),
                name);
        return 0;

out:
        kfree(tl_nexus);
        return ret;
}

static int tcm_loop_drop_nexus(
        struct tcm_loop_tpg *tpg)
{
        struct se_session *se_sess;
        struct tcm_loop_nexus *tl_nexus;

        tl_nexus = tpg->tl_nexus;
        if (!tl_nexus)
                return -ENODEV;

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

        if (atomic_read(&tpg->tl_tpg_port_count)) {
                pr_err("Unable to remove TCM_Loop I_T Nexus with"
                        " active TPG port count: %d\n",
                        atomic_read(&tpg->tl_tpg_port_count));
                return -EPERM;
        }

        pr_debug("TCM_Loop_ConfigFS: Removing I_T Nexus to emulated"
                " %s Initiator Port: %s\n", tcm_loop_dump_proto_id(tpg->tl_hba),
                tl_nexus->se_sess->se_node_acl->initiatorname);
        /*
         * Release the SCSI I_T Nexus to the emulated SAS Target Port
         */
        transport_deregister_session(tl_nexus->se_sess);
        tpg->tl_nexus = NULL;
        kfree(tl_nexus);
        return 0;

}

/* End items for tcm_loop_nexus_cit */

static ssize_t tcm_loop_tpg_show_nexus(
        struct se_portal_group *se_tpg,
        char *page)
{
        struct tcm_loop_tpg *tl_tpg = container_of(se_tpg,
                        struct tcm_loop_tpg, tl_se_tpg);
        struct tcm_loop_nexus *tl_nexus;
        ssize_t ret;

        tl_nexus = tl_tpg->tl_nexus;
        if (!tl_nexus)
                return -ENODEV;

        ret = snprintf(page, PAGE_SIZE, "%s\n",
                tl_nexus->se_sess->se_node_acl->initiatorname);

        return ret;
}

static ssize_t tcm_loop_tpg_store_nexus(
        struct se_portal_group *se_tpg,
        const char *page,
        size_t count)
{
        struct tcm_loop_tpg *tl_tpg = container_of(se_tpg,
                        struct tcm_loop_tpg, tl_se_tpg);
        struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;
        unsigned char i_port[TL_WWN_ADDR_LEN], *ptr, *port_ptr;
        int ret;
        /*
         * Shutdown the active I_T nexus if 'NULL' is passed..
         */
        if (!strncmp(page, "NULL", 4)) {
                ret = tcm_loop_drop_nexus(tl_tpg);
                return (!ret) ? count : ret;
        }
        /*
         * Otherwise make sure the passed virtual Initiator port WWN matches
         * the fabric protocol_id set in tcm_loop_make_scsi_hba(), and call
         * tcm_loop_make_nexus()
         */
        if (strlen(page) >= TL_WWN_ADDR_LEN) {
                pr_err("Emulated NAA Sas Address: %s, exceeds"
                                " max: %d\n", page, TL_WWN_ADDR_LEN);
                return -EINVAL;
        }
        snprintf(&i_port[0], TL_WWN_ADDR_LEN, "%s", page);

        ptr = strstr(i_port, "naa.");
        if (ptr) {
                if (tl_hba->tl_proto_id != SCSI_PROTOCOL_SAS) {
                        pr_err("Passed SAS Initiator Port %s does not"
                                " match target port protoid: %s\n", i_port,
                                tcm_loop_dump_proto_id(tl_hba));
                        return -EINVAL;
                }
                port_ptr = &i_port[0];
                goto check_newline;
        }
        ptr = strstr(i_port, "fc.");
        if (ptr) {
                if (tl_hba->tl_proto_id != SCSI_PROTOCOL_FCP) {
                        pr_err("Passed FCP Initiator Port %s does not"
                                " match target port protoid: %s\n", i_port,
                                tcm_loop_dump_proto_id(tl_hba));
                        return -EINVAL;
                }
                port_ptr = &i_port[3]; /* Skip over "fc." */
                goto check_newline;
        }
        ptr = strstr(i_port, "iqn.");
        if (ptr) {
                if (tl_hba->tl_proto_id != SCSI_PROTOCOL_ISCSI) {
                        pr_err("Passed iSCSI Initiator Port %s does not"
                                " match target port protoid: %s\n", i_port,
                                tcm_loop_dump_proto_id(tl_hba));
                        return -EINVAL;
                }
                port_ptr = &i_port[0];
                goto check_newline;
        }
        pr_err("Unable to locate prefix for emulated Initiator Port:"
                        " %s\n", i_port);
        return -EINVAL;
        /*
         * Clear any trailing newline for the NAA WWN
         */
check_newline:
        if (i_port[strlen(i_port)-1] == '\n')
                i_port[strlen(i_port)-1] = '\0';

        ret = tcm_loop_make_nexus(tl_tpg, port_ptr);
        if (ret < 0)
                return ret;

        return count;
}

TF_TPG_BASE_ATTR(tcm_loop, nexus, S_IRUGO | S_IWUSR);

static ssize_t tcm_loop_tpg_show_transport_status(
        struct se_portal_group *se_tpg,
        char *page)
{
        struct tcm_loop_tpg *tl_tpg = container_of(se_tpg,
                        struct tcm_loop_tpg, tl_se_tpg);
        const char *status = NULL;
        ssize_t ret = -EINVAL;

        switch (tl_tpg->tl_transport_status) {
        case TCM_TRANSPORT_ONLINE:
                status = "online";
                break;
        case TCM_TRANSPORT_OFFLINE:
                status = "offline";
                break;
        default:
                break;
        }

        if (status)
                ret = snprintf(page, PAGE_SIZE, "%s\n", status);

        return ret;
}

static ssize_t tcm_loop_tpg_store_transport_status(
        struct se_portal_group *se_tpg,
        const char *page,
        size_t count)
{
        struct tcm_loop_tpg *tl_tpg = container_of(se_tpg,
                        struct tcm_loop_tpg, tl_se_tpg);

        if (!strncmp(page, "online", 6)) {
                tl_tpg->tl_transport_status = TCM_TRANSPORT_ONLINE;
                return count;
        }
        if (!strncmp(page, "offline", 7)) {
                tl_tpg->tl_transport_status = TCM_TRANSPORT_OFFLINE;
                return count;
        }
        return -EINVAL;
}

TF_TPG_BASE_ATTR(tcm_loop, transport_status, S_IRUGO | S_IWUSR);

static struct configfs_attribute *tcm_loop_tpg_attrs[] = {
        &tcm_loop_tpg_nexus.attr,
        &tcm_loop_tpg_transport_status.attr,
        NULL,
};

/* Start items for tcm_loop_naa_cit */

static struct se_portal_group *tcm_loop_make_naa_tpg(
        struct se_wwn *wwn,
        struct config_group *group,
        const char *name)
{
        struct tcm_loop_hba *tl_hba = container_of(wwn,
                        struct tcm_loop_hba, tl_hba_wwn);
        struct tcm_loop_tpg *tl_tpg;
        char *tpgt_str, *end_ptr;
        int ret;
        unsigned short int tpgt;

        tpgt_str = strstr(name, "tpgt_");
        if (!tpgt_str) {
                pr_err("Unable to locate \"tpgt_#\" directory"
                                " group\n");
                return ERR_PTR(-EINVAL);
        }
        tpgt_str += 5; /* Skip ahead of "tpgt_" */
        tpgt = (unsigned short int) simple_strtoul(tpgt_str, &end_ptr, 0);

        if (tpgt >= TL_TPGS_PER_HBA) {
                pr_err("Passed tpgt: %hu exceeds TL_TPGS_PER_HBA:"
                                " %u\n", tpgt, TL_TPGS_PER_HBA);
                return ERR_PTR(-EINVAL);
        }
        tl_tpg = &tl_hba->tl_hba_tpgs[tpgt];
        tl_tpg->tl_hba = tl_hba;
        tl_tpg->tl_tpgt = tpgt;
        /*
         * Register the tl_tpg as a emulated SAS TCM Target Endpoint
         */
        ret = core_tpg_register(&tcm_loop_fabric_configfs->tf_ops,
                        wwn, &tl_tpg->tl_se_tpg, tl_tpg,
                        TRANSPORT_TPG_TYPE_NORMAL);
        if (ret < 0)
                return ERR_PTR(-ENOMEM);

        pr_debug("TCM_Loop_ConfigFS: Allocated Emulated %s"
                " Target Port %s,t,0x%04x\n", tcm_loop_dump_proto_id(tl_hba),
                config_item_name(&wwn->wwn_group.cg_item), tpgt);

        return &tl_tpg->tl_se_tpg;
}

static void tcm_loop_drop_naa_tpg(
        struct se_portal_group *se_tpg)
{
        struct se_wwn *wwn = se_tpg->se_tpg_wwn;
        struct tcm_loop_tpg *tl_tpg = container_of(se_tpg,
                                struct tcm_loop_tpg, tl_se_tpg);
        struct tcm_loop_hba *tl_hba;
        unsigned short tpgt;

        tl_hba = tl_tpg->tl_hba;
        tpgt = tl_tpg->tl_tpgt;
        /*
         * Release the I_T Nexus for the Virtual SAS link if present
         */
        tcm_loop_drop_nexus(tl_tpg);
        /*
         * Deregister the tl_tpg as a emulated SAS TCM Target Endpoint
         */
        core_tpg_deregister(se_tpg);

        tl_tpg->tl_hba = NULL;
        tl_tpg->tl_tpgt = 0;

        pr_debug("TCM_Loop_ConfigFS: Deallocated Emulated %s"
                " Target Port %s,t,0x%04x\n", tcm_loop_dump_proto_id(tl_hba),
                config_item_name(&wwn->wwn_group.cg_item), tpgt);
}

/* End items for tcm_loop_naa_cit */

/* Start items for tcm_loop_cit */

static struct se_wwn *tcm_loop_make_scsi_hba(
        struct target_fabric_configfs *tf,
        struct config_group *group,
        const char *name)
{
        struct tcm_loop_hba *tl_hba;
        struct Scsi_Host *sh;
        char *ptr;
        int ret, off = 0;

        tl_hba = kzalloc(sizeof(struct tcm_loop_hba), GFP_KERNEL);
        if (!tl_hba) {
                pr_err("Unable to allocate struct tcm_loop_hba\n");
                return ERR_PTR(-ENOMEM);
        }
        /*
         * Determine the emulated Protocol Identifier and Target Port Name
         * based on the incoming configfs directory name.
         */
        ptr = strstr(name, "naa.");
        if (ptr) {
                tl_hba->tl_proto_id = SCSI_PROTOCOL_SAS;
                goto check_len;
        }
        ptr = strstr(name, "fc.");
        if (ptr) {
                tl_hba->tl_proto_id = SCSI_PROTOCOL_FCP;
                off = 3; /* Skip over "fc." */
                goto check_len;
        }
        ptr = strstr(name, "iqn.");
        if (!ptr) {
                pr_err("Unable to locate prefix for emulated Target "
                                "Port: %s\n", name);
                ret = -EINVAL;
                goto out;
        }
        tl_hba->tl_proto_id = SCSI_PROTOCOL_ISCSI;

check_len:
        if (strlen(name) >= TL_WWN_ADDR_LEN) {
                pr_err("Emulated NAA %s Address: %s, exceeds"
                        " max: %d\n", name, tcm_loop_dump_proto_id(tl_hba),
                        TL_WWN_ADDR_LEN);
                ret = -EINVAL;
                goto out;
        }
        snprintf(&tl_hba->tl_wwn_address[0], TL_WWN_ADDR_LEN, "%s", &name[off]);

        /*
         * Call device_register(tl_hba->dev) to register the emulated
         * Linux/SCSI LLD of type struct Scsi_Host at tl_hba->sh after
         * device_register() callbacks in tcm_loop_driver_probe()
         */
        ret = tcm_loop_setup_hba_bus(tl_hba, tcm_loop_hba_no_cnt);
        if (ret)
                goto out;

        sh = tl_hba->sh;
        tcm_loop_hba_no_cnt++;
        pr_debug("TCM_Loop_ConfigFS: Allocated emulated Target"
                " %s Address: %s at Linux/SCSI Host ID: %d\n",
                tcm_loop_dump_proto_id(tl_hba), name, sh->host_no);

        return &tl_hba->tl_hba_wwn;
out:
        kfree(tl_hba);
        return ERR_PTR(ret);
}

static void tcm_loop_drop_scsi_hba(
        struct se_wwn *wwn)
{
        struct tcm_loop_hba *tl_hba = container_of(wwn,
                                struct tcm_loop_hba, tl_hba_wwn);

        pr_debug("TCM_Loop_ConfigFS: Deallocating emulated Target"
                " SAS Address: %s at Linux/SCSI Host ID: %d\n",
                tl_hba->tl_wwn_address, tl_hba->sh->host_no);
        /*
         * Call device_unregister() on the original tl_hba->dev.
         * tcm_loop_fabric_scsi.c:tcm_loop_release_adapter() will
         * release *tl_hba;
         */
        device_unregister(&tl_hba->dev);
}

/* Start items for tcm_loop_cit */
static ssize_t tcm_loop_wwn_show_attr_version(
        struct target_fabric_configfs *tf,
        char *page)
{
        return sprintf(page, "TCM Loopback Fabric module %s\n", TCM_LOOP_VERSION);
}

TF_WWN_ATTR_RO(tcm_loop, version);

static struct configfs_attribute *tcm_loop_wwn_attrs[] = {
        &tcm_loop_wwn_version.attr,
        NULL,
};

/* End items for tcm_loop_cit */

static int tcm_loop_register_configfs(void)
{
        struct target_fabric_configfs *fabric;
        int ret;
        /*
         * Set the TCM Loop HBA counter to zero
         */
        tcm_loop_hba_no_cnt = 0;
        /*
         * Register the top level struct config_item_type with TCM core
         */
        fabric = target_fabric_configfs_init(THIS_MODULE, "loopback");
        if (IS_ERR(fabric)) {
                pr_err("tcm_loop_register_configfs() failed!\n");
                return PTR_ERR(fabric);
        }
        /*
         * Setup the fabric API of function pointers used by target_core_mod
         */
        fabric->tf_ops.get_fabric_name = &tcm_loop_get_fabric_name;
        fabric->tf_ops.get_fabric_proto_ident = &tcm_loop_get_fabric_proto_ident;
        fabric->tf_ops.tpg_get_wwn = &tcm_loop_get_endpoint_wwn;
        fabric->tf_ops.tpg_get_tag = &tcm_loop_get_tag;
        fabric->tf_ops.tpg_get_default_depth = &tcm_loop_get_default_depth;
        fabric->tf_ops.tpg_get_pr_transport_id = &tcm_loop_get_pr_transport_id;
        fabric->tf_ops.tpg_get_pr_transport_id_len =
                                        &tcm_loop_get_pr_transport_id_len;
        fabric->tf_ops.tpg_parse_pr_out_transport_id =
                                        &tcm_loop_parse_pr_out_transport_id;
        fabric->tf_ops.tpg_check_demo_mode = &tcm_loop_check_demo_mode;
        fabric->tf_ops.tpg_check_demo_mode_cache =
                                        &tcm_loop_check_demo_mode_cache;
        fabric->tf_ops.tpg_check_demo_mode_write_protect =
                                        &tcm_loop_check_demo_mode_write_protect;
        fabric->tf_ops.tpg_check_prod_mode_write_protect =
                                        &tcm_loop_check_prod_mode_write_protect;
        /*
         * The TCM loopback fabric module runs in demo-mode to a local
         * virtual SCSI device, so fabric dependent initator ACLs are
         * not required.
         */
        fabric->tf_ops.tpg_alloc_fabric_acl = &tcm_loop_tpg_alloc_fabric_acl;
        fabric->tf_ops.tpg_release_fabric_acl =
                                        &tcm_loop_tpg_release_fabric_acl;
        fabric->tf_ops.tpg_get_inst_index = &tcm_loop_get_inst_index;
        /*
         * Used for setting up remaining TCM resources in process context
         */
        fabric->tf_ops.check_stop_free = &tcm_loop_check_stop_free;
        fabric->tf_ops.release_cmd = &tcm_loop_release_cmd;
        fabric->tf_ops.shutdown_session = &tcm_loop_shutdown_session;
        fabric->tf_ops.close_session = &tcm_loop_close_session;
        fabric->tf_ops.sess_get_index = &tcm_loop_sess_get_index;
        fabric->tf_ops.sess_get_initiator_sid = NULL;
        fabric->tf_ops.write_pending = &tcm_loop_write_pending;
        fabric->tf_ops.write_pending_status = &tcm_loop_write_pending_status;
        /*
         * Not used for TCM loopback
         */
        fabric->tf_ops.set_default_node_attributes =
                                        &tcm_loop_set_default_node_attributes;
        fabric->tf_ops.get_task_tag = &tcm_loop_get_task_tag;
        fabric->tf_ops.get_cmd_state = &tcm_loop_get_cmd_state;
        fabric->tf_ops.queue_data_in = &tcm_loop_queue_data_in;
        fabric->tf_ops.queue_status = &tcm_loop_queue_status;
        fabric->tf_ops.queue_tm_rsp = &tcm_loop_queue_tm_rsp;
        fabric->tf_ops.aborted_task = &tcm_loop_aborted_task;

        /*
         * Setup function pointers for generic logic in target_core_fabric_configfs.c
         */
        fabric->tf_ops.fabric_make_wwn = &tcm_loop_make_scsi_hba;
        fabric->tf_ops.fabric_drop_wwn = &tcm_loop_drop_scsi_hba;
        fabric->tf_ops.fabric_make_tpg = &tcm_loop_make_naa_tpg;
        fabric->tf_ops.fabric_drop_tpg = &tcm_loop_drop_naa_tpg;
        /*
         * fabric_post_link() and fabric_pre_unlink() are used for
         * registration and release of TCM Loop Virtual SCSI LUNs.
         */
        fabric->tf_ops.fabric_post_link = &tcm_loop_port_link;
        fabric->tf_ops.fabric_pre_unlink = &tcm_loop_port_unlink;
        fabric->tf_ops.fabric_make_np = NULL;
        fabric->tf_ops.fabric_drop_np = NULL;
        /*
         * Setup default attribute lists for various fabric->tf_cit_tmpl
         */
        fabric->tf_cit_tmpl.tfc_wwn_cit.ct_attrs = tcm_loop_wwn_attrs;
        fabric->tf_cit_tmpl.tfc_tpg_base_cit.ct_attrs = tcm_loop_tpg_attrs;
        fabric->tf_cit_tmpl.tfc_tpg_attrib_cit.ct_attrs = NULL;
        fabric->tf_cit_tmpl.tfc_tpg_param_cit.ct_attrs = NULL;
        fabric->tf_cit_tmpl.tfc_tpg_np_base_cit.ct_attrs = NULL;
        /*
         * Once fabric->tf_ops has been setup, now register the fabric for
         * use within TCM
         */
        ret = target_fabric_configfs_register(fabric);
        if (ret < 0) {
                pr_err("target_fabric_configfs_register() for"
                                " TCM_Loop failed!\n");
                target_fabric_configfs_free(fabric);
                return -1;
        }
        /*
         * Setup our local pointer to *fabric.
         */
        tcm_loop_fabric_configfs = fabric;
        pr_debug("TCM_LOOP[0] - Set fabric ->"
                        " tcm_loop_fabric_configfs\n");
        return 0;
}

static void tcm_loop_deregister_configfs(void)
{
        if (!tcm_loop_fabric_configfs)
                return;

        target_fabric_configfs_deregister(tcm_loop_fabric_configfs);
        tcm_loop_fabric_configfs = NULL;
        pr_debug("TCM_LOOP[0] - Cleared"
                                " tcm_loop_fabric_configfs\n");
}

static int __init tcm_loop_fabric_init(void)
{
        int ret = -ENOMEM;

        tcm_loop_workqueue = alloc_workqueue("tcm_loop", 0, 0);
        if (!tcm_loop_workqueue)
                goto out;

        tcm_loop_cmd_cache = kmem_cache_create("tcm_loop_cmd_cache",
                                sizeof(struct tcm_loop_cmd),
                                __alignof__(struct tcm_loop_cmd),
                                0, NULL);
        if (!tcm_loop_cmd_cache) {
                pr_debug("kmem_cache_create() for"
                        " tcm_loop_cmd_cache failed\n");
                goto out_destroy_workqueue;
        }

        ret = tcm_loop_alloc_core_bus();
        if (ret)
                goto out_destroy_cache;

        ret = tcm_loop_register_configfs();
        if (ret)
                goto out_release_core_bus;

        return 0;

out_release_core_bus:
        tcm_loop_release_core_bus();
out_destroy_cache:
        kmem_cache_destroy(tcm_loop_cmd_cache);
out_destroy_workqueue:
        destroy_workqueue(tcm_loop_workqueue);
out:
        return ret;
}

static void __exit tcm_loop_fabric_exit(void)
{
        tcm_loop_deregister_configfs();
        tcm_loop_release_core_bus();
        kmem_cache_destroy(tcm_loop_cmd_cache);
        destroy_workqueue(tcm_loop_workqueue);
}

MODULE_DESCRIPTION("TCM loopback virtual Linux/SCSI fabric module");
MODULE_AUTHOR("Nicholas A. Bellinger <nab@risingtidesystems.com>");
MODULE_LICENSE("GPL");
module_init(tcm_loop_fabric_init);
module_exit(tcm_loop_fabric_exit);