/*******************************************************************************
 * Filename:  target_core_hba.c
 *
 * This file contains the TCM HBA Transport related functions.
 *
 * (c) Copyright 2003-2013 Datera, Inc.
 *
 * Nicholas A. Bellinger <nab@kernel.org>
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 ******************************************************************************/

#include <linux/net.h>
#include <linux/string.h>
#include <linux/timer.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/in.h>
#include <linux/module.h>
#include <net/sock.h>
#include <net/tcp.h>

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

#include "target_core_internal.h"

static LIST_HEAD(backend_list);
static DEFINE_MUTEX(backend_mutex);

static u32 hba_id_counter;

static DEFINE_SPINLOCK(hba_lock);
static LIST_HEAD(hba_list);


int transport_backend_register(const struct target_backend_ops *ops)
{
        struct target_backend *tb, *old;

        tb = kzalloc(sizeof(*tb), GFP_KERNEL);
        if (!tb)
                return -ENOMEM;
        tb->ops = ops;

        mutex_lock(&backend_mutex);
        list_for_each_entry(old, &backend_list, list) {
                if (!strcmp(old->ops->name, ops->name)) {
                        pr_err("backend %s already registered.\n", ops->name);
                        mutex_unlock(&backend_mutex);
                        kfree(tb);
                        return -EEXIST;
                }
        }
        target_setup_backend_cits(tb);
        list_add_tail(&tb->list, &backend_list);
        mutex_unlock(&backend_mutex);

        pr_debug("TCM: Registered subsystem plugin: %s struct module: %p\n",
                        ops->name, ops->owner);
        return 0;
}
EXPORT_SYMBOL(transport_backend_register);

void target_backend_unregister(const struct target_backend_ops *ops)
{
        struct target_backend *tb;

        mutex_lock(&backend_mutex);
        list_for_each_entry(tb, &backend_list, list) {
                if (tb->ops == ops) {
                        list_del(&tb->list);
                        mutex_unlock(&backend_mutex);
                        /*
                         * Wait for any outstanding backend driver ->rcu_head
                         * callbacks to complete post TBO->free_device() ->
                         * call_rcu(), before allowing backend driver module
                         * unload of target_backend_ops->owner to proceed.
                         */
                        rcu_barrier();
                        kfree(tb);
                        return;
                }
        }
        mutex_unlock(&backend_mutex);
}
EXPORT_SYMBOL(target_backend_unregister);

static struct target_backend *core_get_backend(const char *name)
{
        struct target_backend *tb;

        mutex_lock(&backend_mutex);
        list_for_each_entry(tb, &backend_list, list) {
                if (!strcmp(tb->ops->name, name))
                        goto found;
        }
        mutex_unlock(&backend_mutex);
        return NULL;
found:
        if (tb->ops->owner && !try_module_get(tb->ops->owner))
                tb = NULL;
        mutex_unlock(&backend_mutex);
        return tb;
}

struct se_hba *
core_alloc_hba(const char *plugin_name, u32 plugin_dep_id, u32 hba_flags)
{
        struct se_hba *hba;
        int ret = 0;

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

        spin_lock_init(&hba->device_lock);
        mutex_init(&hba->hba_access_mutex);

        hba->hba_index = scsi_get_new_index(SCSI_INST_INDEX);
        hba->hba_flags |= hba_flags;

        hba->backend = core_get_backend(plugin_name);
        if (!hba->backend) {
                ret = -EINVAL;
                goto out_free_hba;
        }

        ret = hba->backend->ops->attach_hba(hba, plugin_dep_id);
        if (ret < 0)
                goto out_module_put;

        spin_lock(&hba_lock);
        hba->hba_id = hba_id_counter++;
        list_add_tail(&hba->hba_node, &hba_list);
        spin_unlock(&hba_lock);

        pr_debug("CORE_HBA[%d] - Attached HBA to Generic Target"
                        " Core\n", hba->hba_id);

        return hba;

out_module_put:
        module_put(hba->backend->ops->owner);
        hba->backend = NULL;
out_free_hba:
        kfree(hba);
        return ERR_PTR(ret);
}

int
core_delete_hba(struct se_hba *hba)
{
        WARN_ON(hba->dev_count);

        hba->backend->ops->detach_hba(hba);

        spin_lock(&hba_lock);
        list_del(&hba->hba_node);
        spin_unlock(&hba_lock);

        pr_debug("CORE_HBA[%d] - Detached HBA from Generic Target"
                        " Core\n", hba->hba_id);

        module_put(hba->backend->ops->owner);

        hba->backend = NULL;
        kfree(hba);
        return 0;
}

bool target_sense_desc_format(struct se_device *dev)
{
        return (dev) ? dev->transport->get_blocks(dev) > U32_MAX : false;
}