/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2012 The FreeBSD Foundation
 *
 * This software was developed by Edward Tomasz Napierala under sponsorship
 * from the FreeBSD Foundation.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

/*
 * iSCSI Common Layer.  It's used by both the initiator and target to send
 * and receive iSCSI PDUs.
 */

#include <sys/param.h>
#include <sys/condvar.h>
#include <sys/conf.h>
#include <sys/lock.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/module.h>
#include <sys/queue.h>
#include <sys/sbuf.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/sx.h>

#include <dev/iscsi/icl.h>
#include <icl_conn_if.h>

struct icl_module {
        TAILQ_ENTRY(icl_module)         im_next;
        char                            *im_name;
        bool                            im_iser;
        int                             im_priority;
        int                             (*im_limits)(struct icl_drv_limits *idl,
                                            int socket);
        struct icl_conn                 *(*im_new_conn)(const char *name,
                                            struct mtx *lock);
};

struct icl_softc {
        struct sx                       sc_lock;
        TAILQ_HEAD(, icl_module)        sc_modules;
};

static int sysctl_kern_icl_offloads(SYSCTL_HANDLER_ARGS);
static MALLOC_DEFINE(M_ICL, "icl", "iSCSI Common Layer");
static struct icl_softc *sc;

SYSCTL_NODE(_kern, OID_AUTO, icl, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
    "iSCSI Common Layer");
int icl_debug = 1;
SYSCTL_INT(_kern_icl, OID_AUTO, debug, CTLFLAG_RWTUN,
    &icl_debug, 0, "Enable debug messages");
SYSCTL_PROC(_kern_icl, OID_AUTO, offloads,
    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE,
    NULL, false, sysctl_kern_icl_offloads, "A",
    "List of ICL modules");
SYSCTL_PROC(_kern_icl, OID_AUTO, iser_offloads,
    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE,
    NULL, true, sysctl_kern_icl_offloads, "A",
    "List of iSER ICL modules");

static int
sysctl_kern_icl_offloads(SYSCTL_HANDLER_ARGS)
{
        const struct icl_module *im;
        struct sbuf sb;
        bool iser = arg2;
        int error;

        sbuf_new(&sb, NULL, 256, SBUF_AUTOEXTEND | SBUF_INCLUDENUL);

        sx_slock(&sc->sc_lock);
        TAILQ_FOREACH(im, &sc->sc_modules, im_next) {
                if (im->im_iser != iser)
                        continue;
                if (im != TAILQ_FIRST(&sc->sc_modules))
                        sbuf_putc(&sb, ' ');
                sbuf_printf(&sb, "%s", im->im_name);
        }
        sx_sunlock(&sc->sc_lock);

        error = sbuf_finish(&sb);
        if (error == 0)
                error = SYSCTL_OUT(req, sbuf_data(&sb), sbuf_len(&sb));
        sbuf_delete(&sb);
        return (error);
}

static struct icl_module *
icl_find(const char *name, bool iser, bool quiet)
{
        struct icl_module *im, *im_max;

        sx_assert(&sc->sc_lock, SA_LOCKED);

        /*
         * If the name was not specified, pick a module with highest
         * priority.
         */
        if (name == NULL || name[0] == '\0') {
                im_max = NULL;
                TAILQ_FOREACH(im, &sc->sc_modules, im_next) {
                        if (im->im_iser != iser)
                                continue;
                        if (im_max == NULL ||
                            im->im_priority > im_max->im_priority)
                                im_max = im;
                }

                if (iser && im_max == NULL && !quiet)
                        ICL_WARN("no iSER-capable offload found");

                return (im_max);
        }

        TAILQ_FOREACH(im, &sc->sc_modules, im_next) {
                if (strcasecmp(im->im_name, name) != 0)
                        continue;

                if (!im->im_iser && iser && !quiet) {
                        ICL_WARN("offload \"%s\" is not iSER-capable", name);
                        return (NULL);
                }
                if (im->im_iser && !iser && !quiet) {
                        ICL_WARN("offload \"%s\" is iSER-only", name);
                        return (NULL);
                }

                return (im);
        }

        if (!quiet)
                ICL_WARN("offload \"%s\" not found", name);

        return (NULL);
}

struct icl_conn *
icl_new_conn(const char *offload, bool iser, const char *name, struct mtx *lock)
{
        struct icl_module *im;
        struct icl_conn *ic;

        sx_slock(&sc->sc_lock);
        im = icl_find(offload, iser, false);
        if (im == NULL) {
                sx_sunlock(&sc->sc_lock);
                return (NULL);
        }

        ic = im->im_new_conn(name, lock);
        sx_sunlock(&sc->sc_lock);

        return (ic);
}

int
icl_limits(const char *offload, bool iser, int socket,
    struct icl_drv_limits *idl)
{
        struct icl_module *im;
        int error;

        bzero(idl, sizeof(*idl));
        sx_slock(&sc->sc_lock);
        im = icl_find(offload, iser, false);
        if (im == NULL) {
                sx_sunlock(&sc->sc_lock);
                return (ENXIO);
        }

        error = im->im_limits(idl, socket);
        sx_sunlock(&sc->sc_lock);

        /*
         * Validate the limits provided by the driver against values allowed by
         * the iSCSI RFC.  0 means iscsid/ctld should pick a reasonable value.
         *
         * Note that max_send_dsl is an internal implementation detail and not
         * part of the RFC.
         */
#define OUT_OF_RANGE(x, lo, hi) ((x) != 0 && ((x) < (lo) || (x) > (hi)))
        if (error == 0 &&
            (OUT_OF_RANGE(idl->idl_max_recv_data_segment_length, 512, 16777215) ||
            OUT_OF_RANGE(idl->idl_max_send_data_segment_length, 512, 16777215) ||
            OUT_OF_RANGE(idl->idl_max_burst_length, 512, 16777215) ||
            OUT_OF_RANGE(idl->idl_first_burst_length, 512, 16777215))) {
                error = EINVAL;
        }
#undef OUT_OF_RANGE

        /*
         * If both first_burst and max_burst are provided then first_burst must
         * not exceed max_burst.
         */
        if (error == 0 && idl->idl_first_burst_length > 0 &&
            idl->idl_max_burst_length > 0 &&
            idl->idl_first_burst_length > idl->idl_max_burst_length) {
                error = EINVAL;
        }

        return (error);
}

int
icl_register(const char *offload, bool iser, int priority,
    int (*limits)(struct icl_drv_limits *, int),
    struct icl_conn *(*new_conn)(const char *, struct mtx *))
{
        struct icl_module *im;

        sx_xlock(&sc->sc_lock);
        im = icl_find(offload, iser, true);
        if (im != NULL) {
                ICL_WARN("offload \"%s\" already registered", offload);
                sx_xunlock(&sc->sc_lock);
                return (EBUSY);
        }

        im = malloc(sizeof(*im), M_ICL, M_ZERO | M_WAITOK);
        im->im_name = strdup(offload, M_ICL);
        im->im_iser = iser;
        im->im_priority = priority;
        im->im_limits = limits;
        im->im_new_conn = new_conn;

        TAILQ_INSERT_HEAD(&sc->sc_modules, im, im_next);
        sx_xunlock(&sc->sc_lock);

        ICL_DEBUG("offload \"%s\" registered", offload);
        return (0);
}

int
icl_unregister(const char *offload, bool rdma)
{
        struct icl_module *im;

        sx_xlock(&sc->sc_lock);
        im = icl_find(offload, rdma, true);
        if (im == NULL) {
                ICL_WARN("offload \"%s\" not registered", offload);
                sx_xunlock(&sc->sc_lock);
                return (ENXIO);
        }

        TAILQ_REMOVE(&sc->sc_modules, im, im_next);
        sx_xunlock(&sc->sc_lock);

        free(im->im_name, M_ICL);
        free(im, M_ICL);

        ICL_DEBUG("offload \"%s\" unregistered", offload);
        return (0);
}

static int
icl_load(void)
{

        sc = malloc(sizeof(*sc), M_ICL, M_ZERO | M_WAITOK);
        sx_init(&sc->sc_lock, "icl");
        TAILQ_INIT(&sc->sc_modules);

        return (0);
}

static int
icl_unload(void)
{

        sx_slock(&sc->sc_lock);
        KASSERT(TAILQ_EMPTY(&sc->sc_modules), ("still have modules"));
        sx_sunlock(&sc->sc_lock);

        sx_destroy(&sc->sc_lock);
        free(sc, M_ICL);

        return (0);
}

static int
icl_modevent(module_t mod, int what, void *arg)
{

        switch (what) {
        case MOD_LOAD:
                return (icl_load());
        case MOD_UNLOAD:
                return (icl_unload());
        default:
                return (EINVAL);
        }
}

moduledata_t icl_data = {
        "icl",
        icl_modevent,
        0
};

DECLARE_MODULE(icl, icl_data, SI_SUB_DRIVERS, SI_ORDER_FIRST);
MODULE_VERSION(icl, 1);