/*
 * SCSI RDMA (SRP) transport class
 *
 * Copyright (C) 2007 FUJITA Tomonori <tomof@acm.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, version 2 of the
 * License.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/jiffies.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/string.h>

#include <scsi/scsi.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_transport.h>
#include <scsi/scsi_transport_srp.h>
#include "scsi_transport_srp_internal.h"

struct srp_host_attrs {
        atomic_t next_port_id;
};
#define to_srp_host_attrs(host) ((struct srp_host_attrs *)(host)->shost_data)

#define SRP_HOST_ATTRS 0
#define SRP_RPORT_ATTRS 3

struct srp_internal {
        struct scsi_transport_template t;
        struct srp_function_template *f;

        struct device_attribute *host_attrs[SRP_HOST_ATTRS + 1];

        struct device_attribute *rport_attrs[SRP_RPORT_ATTRS + 1];
        struct transport_container rport_attr_cont;
};

#define to_srp_internal(tmpl) container_of(tmpl, struct srp_internal, t)

#define dev_to_rport(d) container_of(d, struct srp_rport, dev)
#define transport_class_to_srp_rport(dev) dev_to_rport((dev)->parent)

static int srp_host_setup(struct transport_container *tc, struct device *dev,
                          struct device *cdev)
{
        struct Scsi_Host *shost = dev_to_shost(dev);
        struct srp_host_attrs *srp_host = to_srp_host_attrs(shost);

        atomic_set(&srp_host->next_port_id, 0);
        return 0;
}

static DECLARE_TRANSPORT_CLASS(srp_host_class, "srp_host", srp_host_setup,
                               NULL, NULL);

static DECLARE_TRANSPORT_CLASS(srp_rport_class, "srp_remote_ports",
                               NULL, NULL, NULL);

#define SRP_PID(p) \
        (p)->port_id[0], (p)->port_id[1], (p)->port_id[2], (p)->port_id[3], \
        (p)->port_id[4], (p)->port_id[5], (p)->port_id[6], (p)->port_id[7], \
        (p)->port_id[8], (p)->port_id[9], (p)->port_id[10], (p)->port_id[11], \
        (p)->port_id[12], (p)->port_id[13], (p)->port_id[14], (p)->port_id[15]

#define SRP_PID_FMT "%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x:" \
        "%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x"

static ssize_t
show_srp_rport_id(struct device *dev, struct device_attribute *attr,
                  char *buf)
{
        struct srp_rport *rport = transport_class_to_srp_rport(dev);
        return sprintf(buf, SRP_PID_FMT "\n", SRP_PID(rport));
}

static DEVICE_ATTR(port_id, S_IRUGO, show_srp_rport_id, NULL);

static const struct {
        u32 value;
        char *name;
} srp_rport_role_names[] = {
        {SRP_RPORT_ROLE_INITIATOR, "SRP Initiator"},
        {SRP_RPORT_ROLE_TARGET, "SRP Target"},
};

static ssize_t
show_srp_rport_roles(struct device *dev, struct device_attribute *attr,
                     char *buf)
{
        struct srp_rport *rport = transport_class_to_srp_rport(dev);
        int i;
        char *name = NULL;

        for (i = 0; i < ARRAY_SIZE(srp_rport_role_names); i++)
                if (srp_rport_role_names[i].value == rport->roles) {
                        name = srp_rport_role_names[i].name;
                        break;
                }
        return sprintf(buf, "%s\n", name ? : "unknown");
}

static DEVICE_ATTR(roles, S_IRUGO, show_srp_rport_roles, NULL);

static ssize_t store_srp_rport_delete(struct device *dev,
                                      struct device_attribute *attr,
                                      const char *buf, size_t count)
{
        struct srp_rport *rport = transport_class_to_srp_rport(dev);
        struct Scsi_Host *shost = dev_to_shost(dev);
        struct srp_internal *i = to_srp_internal(shost->transportt);

        if (i->f->rport_delete) {
                i->f->rport_delete(rport);
                return count;
        } else {
                return -ENOSYS;
        }
}

static DEVICE_ATTR(delete, S_IWUSR, NULL, store_srp_rport_delete);

static void srp_rport_release(struct device *dev)
{
        struct srp_rport *rport = dev_to_rport(dev);

        put_device(dev->parent);
        kfree(rport);
}

static int scsi_is_srp_rport(const struct device *dev)
{
        return dev->release == srp_rport_release;
}

static int srp_rport_match(struct attribute_container *cont,
                           struct device *dev)
{
        struct Scsi_Host *shost;
        struct srp_internal *i;

        if (!scsi_is_srp_rport(dev))
                return 0;

        shost = dev_to_shost(dev->parent);
        if (!shost->transportt)
                return 0;
        if (shost->transportt->host_attrs.ac.class != &srp_host_class.class)
                return 0;

        i = to_srp_internal(shost->transportt);
        return &i->rport_attr_cont.ac == cont;
}

static int srp_host_match(struct attribute_container *cont, struct device *dev)
{
        struct Scsi_Host *shost;
        struct srp_internal *i;

        if (!scsi_is_host_device(dev))
                return 0;

        shost = dev_to_shost(dev);
        if (!shost->transportt)
                return 0;
        if (shost->transportt->host_attrs.ac.class != &srp_host_class.class)
                return 0;

        i = to_srp_internal(shost->transportt);
        return &i->t.host_attrs.ac == cont;
}

/**
 * srp_rport_add - add a SRP remote port to the device hierarchy
 * @shost:      scsi host the remote port is connected to.
 * @ids:        The port id for the remote port.
 *
 * Publishes a port to the rest of the system.
 */
struct srp_rport *srp_rport_add(struct Scsi_Host *shost,
                                struct srp_rport_identifiers *ids)
{
        struct srp_rport *rport;
        struct device *parent = &shost->shost_gendev;
        int id, ret;

        rport = kzalloc(sizeof(*rport), GFP_KERNEL);
        if (!rport)
                return ERR_PTR(-ENOMEM);

        device_initialize(&rport->dev);

        rport->dev.parent = get_device(parent);
        rport->dev.release = srp_rport_release;

        memcpy(rport->port_id, ids->port_id, sizeof(rport->port_id));
        rport->roles = ids->roles;

        id = atomic_inc_return(&to_srp_host_attrs(shost)->next_port_id);
        dev_set_name(&rport->dev, "port-%d:%d", shost->host_no, id);

        transport_setup_device(&rport->dev);

        ret = device_add(&rport->dev);
        if (ret) {
                transport_destroy_device(&rport->dev);
                put_device(&rport->dev);
                return ERR_PTR(ret);
        }

        if (shost->active_mode & MODE_TARGET &&
            ids->roles == SRP_RPORT_ROLE_INITIATOR) {
                ret = srp_tgt_it_nexus_create(shost, (unsigned long)rport,
                                              rport->port_id);
                if (ret) {
                        device_del(&rport->dev);
                        transport_destroy_device(&rport->dev);
                        put_device(&rport->dev);
                        return ERR_PTR(ret);
                }
        }

        transport_add_device(&rport->dev);
        transport_configure_device(&rport->dev);

        return rport;
}
EXPORT_SYMBOL_GPL(srp_rport_add);

/**
 * srp_rport_del  -  remove a SRP remote port
 * @rport:      SRP remote port to remove
 *
 * Removes the specified SRP remote port.
 */
void srp_rport_del(struct srp_rport *rport)
{
        struct device *dev = &rport->dev;
        struct Scsi_Host *shost = dev_to_shost(dev->parent);

        if (shost->active_mode & MODE_TARGET &&
            rport->roles == SRP_RPORT_ROLE_INITIATOR)
                srp_tgt_it_nexus_destroy(shost, (unsigned long)rport);

        transport_remove_device(dev);
        device_del(dev);
        transport_destroy_device(dev);
        put_device(dev);
}
EXPORT_SYMBOL_GPL(srp_rport_del);

static int do_srp_rport_del(struct device *dev, void *data)
{
        if (scsi_is_srp_rport(dev))
                srp_rport_del(dev_to_rport(dev));
        return 0;
}

/**
 * srp_remove_host  -  tear down a Scsi_Host's SRP data structures
 * @shost:      Scsi Host that is torn down
 *
 * Removes all SRP remote ports for a given Scsi_Host.
 * Must be called just before scsi_remove_host for SRP HBAs.
 */
void srp_remove_host(struct Scsi_Host *shost)
{
        device_for_each_child(&shost->shost_gendev, NULL, do_srp_rport_del);
}
EXPORT_SYMBOL_GPL(srp_remove_host);

static int srp_tsk_mgmt_response(struct Scsi_Host *shost, u64 nexus, u64 tm_id,
                                 int result)
{
        struct srp_internal *i = to_srp_internal(shost->transportt);
        return i->f->tsk_mgmt_response(shost, nexus, tm_id, result);
}

static int srp_it_nexus_response(struct Scsi_Host *shost, u64 nexus, int result)
{
        struct srp_internal *i = to_srp_internal(shost->transportt);
        return i->f->it_nexus_response(shost, nexus, result);
}

/**
 * srp_attach_transport  -  instantiate SRP transport template
 * @ft:         SRP transport class function template
 */
struct scsi_transport_template *
srp_attach_transport(struct srp_function_template *ft)
{
        int count;
        struct srp_internal *i;

        i = kzalloc(sizeof(*i), GFP_KERNEL);
        if (!i)
                return NULL;

        i->t.tsk_mgmt_response = srp_tsk_mgmt_response;
        i->t.it_nexus_response = srp_it_nexus_response;

        i->t.host_size = sizeof(struct srp_host_attrs);
        i->t.host_attrs.ac.attrs = &i->host_attrs[0];
        i->t.host_attrs.ac.class = &srp_host_class.class;
        i->t.host_attrs.ac.match = srp_host_match;
        i->host_attrs[0] = NULL;
        transport_container_register(&i->t.host_attrs);

        i->rport_attr_cont.ac.attrs = &i->rport_attrs[0];
        i->rport_attr_cont.ac.class = &srp_rport_class.class;
        i->rport_attr_cont.ac.match = srp_rport_match;

        count = 0;
        i->rport_attrs[count++] = &dev_attr_port_id;
        i->rport_attrs[count++] = &dev_attr_roles;
        if (ft->rport_delete)
                i->rport_attrs[count++] = &dev_attr_delete;
        i->rport_attrs[count++] = NULL;
        BUG_ON(count > ARRAY_SIZE(i->rport_attrs));

        transport_container_register(&i->rport_attr_cont);

        i->f = ft;

        return &i->t;
}
EXPORT_SYMBOL_GPL(srp_attach_transport);

/**
 * srp_release_transport  -  release SRP transport template instance
 * @t:          transport template instance
 */
void srp_release_transport(struct scsi_transport_template *t)
{
        struct srp_internal *i = to_srp_internal(t);

        transport_container_unregister(&i->t.host_attrs);
        transport_container_unregister(&i->rport_attr_cont);

        kfree(i);
}
EXPORT_SYMBOL_GPL(srp_release_transport);

static __init int srp_transport_init(void)
{
        int ret;

        ret = transport_class_register(&srp_host_class);
        if (ret)
                return ret;
        ret = transport_class_register(&srp_rport_class);
        if (ret)
                goto unregister_host_class;

        return 0;
unregister_host_class:
        transport_class_unregister(&srp_host_class);
        return ret;
}

static void __exit srp_transport_exit(void)
{
        transport_class_unregister(&srp_host_class);
        transport_class_unregister(&srp_rport_class);
}

MODULE_AUTHOR("FUJITA Tomonori");
MODULE_DESCRIPTION("SRP Transport Attributes");
MODULE_LICENSE("GPL");

module_init(srp_transport_init);
module_exit(srp_transport_exit);