/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2011-2012 Stefan Bethke.
 * All rights reserved.
 *
 * 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.
 */

#include <sys/param.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/systm.h>

#include <net/if.h>
#include <net/if_media.h>

#include <dev/etherswitch/miiproxy.h>
#include <dev/mii/mii.h>
#include <dev/mii/miivar.h>

#include "mdio_if.h"
#include "miibus_if.h"


MALLOC_DECLARE(M_MIIPROXY);
MALLOC_DEFINE(M_MIIPROXY, "miiproxy", "miiproxy data structures");

driver_t miiproxy_driver;
driver_t mdioproxy_driver;

struct miiproxy_softc {
        device_t        parent;
        device_t        proxy;
        device_t        mdio;
};

struct mdioproxy_softc {
};

/*
 * The rendezvous data structures and functions allow two device endpoints to
 * match up, so that the proxy endpoint can be associated with a target
 * endpoint.  The proxy has to know the device name of the target that it
 * wants to associate with, for example through a hint.  The rendezvous code
 * makes no assumptions about the devices that want to meet.
 */
struct rendezvous_entry;

enum rendezvous_op {
        RENDEZVOUS_ATTACH,
        RENDEZVOUS_DETACH
};

typedef int (*rendezvous_callback_t)(enum rendezvous_op,
    struct rendezvous_entry *);

static SLIST_HEAD(rendezvoushead, rendezvous_entry) rendezvoushead =
    SLIST_HEAD_INITIALIZER(rendezvoushead);

struct rendezvous_endpoint {
        device_t                device;
        const char              *name;
        rendezvous_callback_t   callback;
};

struct rendezvous_entry {
        SLIST_ENTRY(rendezvous_entry)   entries;
        struct rendezvous_endpoint      proxy;
        struct rendezvous_endpoint      target;
};

/*
 * Call the callback routines for both the proxy and the target.  If either
 * returns an error, undo the attachment.
 */
static int
rendezvous_attach(struct rendezvous_entry *e, struct rendezvous_endpoint *ep)
{
        int error;

        error = e->proxy.callback(RENDEZVOUS_ATTACH, e);
        if (error == 0) {
                error = e->target.callback(RENDEZVOUS_ATTACH, e);
                if (error != 0) {
                        e->proxy.callback(RENDEZVOUS_DETACH, e);
                        ep->device = NULL;
                        ep->callback = NULL;
                }
        }
        return (error);
}

/*
 * Create an entry for the proxy in the rendezvous list.  The name parameter
 * indicates the name of the device that is the target endpoint for this
 * rendezvous.  The callback will be invoked as soon as the target is
 * registered: either immediately if the target registered itself earlier,
 * or once the target registers.  Returns ENXIO if the target has not yet
 * registered.
 */
static int
rendezvous_register_proxy(device_t dev, const char *name,
    rendezvous_callback_t callback)
{
        struct rendezvous_entry *e;

        KASSERT(callback != NULL, ("callback must be set"));
        SLIST_FOREACH(e, &rendezvoushead, entries) {
                if (strcmp(name, e->target.name) == 0) {
                        /* the target is already attached */
                        e->proxy.name = device_get_nameunit(dev);
                        e->proxy.device = dev;
                        e->proxy.callback = callback;
                        return (rendezvous_attach(e, &e->proxy));
                }
        }
        e = malloc(sizeof(*e), M_MIIPROXY, M_WAITOK | M_ZERO);
        e->proxy.name = device_get_nameunit(dev);
        e->proxy.device = dev;
        e->proxy.callback = callback;
        e->target.name = name;
        SLIST_INSERT_HEAD(&rendezvoushead, e, entries);
        return (ENXIO);
}

/*
 * Create an entry in the rendezvous list for the target.
 * Returns ENXIO if the proxy has not yet registered.
 */
static int
rendezvous_register_target(device_t dev, rendezvous_callback_t callback)
{
        struct rendezvous_entry *e;
        const char *name;

        KASSERT(callback != NULL, ("callback must be set"));
        name = device_get_nameunit(dev);
        SLIST_FOREACH(e, &rendezvoushead, entries) {
                if (strcmp(name, e->target.name) == 0) {
                        e->target.device = dev;
                        e->target.callback = callback;
                        return (rendezvous_attach(e, &e->target));
                }
        }
        e = malloc(sizeof(*e), M_MIIPROXY, M_WAITOK | M_ZERO);
        e->target.name = name;
        e->target.device = dev;
        e->target.callback = callback;
        SLIST_INSERT_HEAD(&rendezvoushead, e, entries);
        return (ENXIO);
}

/*
 * Remove the registration for the proxy.
 */
static int
rendezvous_unregister_proxy(device_t dev)
{
        struct rendezvous_entry *e;
        int error = 0;

        SLIST_FOREACH(e, &rendezvoushead, entries) {
                if (e->proxy.device == dev) {
                        if (e->target.device == NULL) {
                                SLIST_REMOVE(&rendezvoushead, e, rendezvous_entry, entries);
                                free(e, M_MIIPROXY);
                                return (0);
                        } else {
                                e->proxy.callback(RENDEZVOUS_DETACH, e);
                                e->target.callback(RENDEZVOUS_DETACH, e);
                        }
                        e->proxy.device = NULL;
                        e->proxy.callback = NULL;
                        return (error);
                }
        }
        return (ENOENT);
}

/*
 * Remove the registration for the target.
 */
static int
rendezvous_unregister_target(device_t dev)
{
        struct rendezvous_entry *e;
        int error = 0;

        SLIST_FOREACH(e, &rendezvoushead, entries) {
                if (e->target.device == dev) {
                        if (e->proxy.device == NULL) {
                                SLIST_REMOVE(&rendezvoushead, e, rendezvous_entry, entries);
                                free(e, M_MIIPROXY);
                                return (0);
                        } else {
                                e->proxy.callback(RENDEZVOUS_DETACH, e);
                                e->target.callback(RENDEZVOUS_DETACH, e);
                        }
                        e->target.device = NULL;
                        e->target.callback = NULL;
                        return (error);
                }
        }
        return (ENOENT);
}

/*
 * Functions of the proxy that is interposed between the ethernet interface
 * driver and the miibus device.
 */

static int
miiproxy_rendezvous_callback(enum rendezvous_op op, struct rendezvous_entry *rendezvous)
{
        struct miiproxy_softc *sc = device_get_softc(rendezvous->proxy.device);

        switch (op) {
        case RENDEZVOUS_ATTACH:
                sc->mdio = device_get_parent(rendezvous->target.device);
                break;
        case RENDEZVOUS_DETACH:
                sc->mdio = NULL;
                break;
        }
        return (0);
}

static int
miiproxy_probe(device_t dev)
{
        device_set_desc(dev, "MII/MDIO proxy, MII side");

        return (BUS_PROBE_SPECIFIC);
}

static int
miiproxy_attach(device_t dev)
{

        /*
         * The ethernet interface needs to call mii_attach_proxy() to pass
         * the relevant parameters for rendezvous with the MDIO target.
         */
        bus_attach_children(dev);
        return (0);
}

static int
miiproxy_detach(device_t dev)
{

        rendezvous_unregister_proxy(dev);
        bus_generic_detach(dev);
        return (0);
}

static int
miiproxy_readreg(device_t dev, int phy, int reg)
{
        struct miiproxy_softc *sc = device_get_softc(dev);

        if (sc->mdio != NULL)
                return (MDIO_READREG(sc->mdio, phy, reg));
        return (-1);
}

static int
miiproxy_writereg(device_t dev, int phy, int reg, int val)
{
        struct miiproxy_softc *sc = device_get_softc(dev);

        if (sc->mdio != NULL)
                return (MDIO_WRITEREG(sc->mdio, phy, reg, val));
        return (-1);
}

static void
miiproxy_statchg(device_t dev)
{

        MIIBUS_STATCHG(device_get_parent(dev));
}

static void
miiproxy_linkchg(device_t dev)
{

        MIIBUS_LINKCHG(device_get_parent(dev));
}

static void
miiproxy_mediainit(device_t dev)
{

        MIIBUS_MEDIAINIT(device_get_parent(dev));
}

/*
 * Functions for the MDIO target device driver.
 */
static int
mdioproxy_rendezvous_callback(enum rendezvous_op op, struct rendezvous_entry *rendezvous)
{
        return (0);
}

static void
mdioproxy_identify(driver_t *driver, device_t parent)
{
        if (device_find_child(parent, driver->name, DEVICE_UNIT_ANY) == NULL) {
                BUS_ADD_CHILD(parent, 0, driver->name, DEVICE_UNIT_ANY);
        }
}

static int
mdioproxy_probe(device_t dev)
{
        device_set_desc(dev, "MII/MDIO proxy, MDIO side");

        return (BUS_PROBE_SPECIFIC);
}

static int
mdioproxy_attach(device_t dev)
{

        rendezvous_register_target(dev, mdioproxy_rendezvous_callback);
        bus_attach_children(dev);
        return (0);
}

static int
mdioproxy_detach(device_t dev)
{

        rendezvous_unregister_target(dev);
        bus_generic_detach(dev);
        return (0);
}

/*
 * Attach this proxy in place of miibus.  The target MDIO must be attached
 * already.  Returns NULL on error.
 */
device_t
mii_attach_proxy(device_t dev)
{
        struct miiproxy_softc *sc;
        const char      *name;
        device_t        miiproxy;

        if (resource_string_value(device_get_name(dev),
            device_get_unit(dev), "mdio", &name) != 0) {
                if (bootverbose)
                        printf("mii_attach_proxy: not attaching, no mdio"
                            " device hint for %s\n", device_get_nameunit(dev));
                return (NULL);
        }

        miiproxy = device_add_child(dev, miiproxy_driver.name, DEVICE_UNIT_ANY);
        bus_attach_children(dev);
        sc = device_get_softc(miiproxy);
        sc->parent = dev;
        sc->proxy = miiproxy;
        if (rendezvous_register_proxy(miiproxy, name, miiproxy_rendezvous_callback) != 0) {
                device_printf(dev, "can't attach proxy\n");
                return (NULL);
        }
        device_printf(miiproxy, "attached to target %s\n", device_get_nameunit(sc->mdio));
        return (miiproxy);
}

static device_method_t miiproxy_methods[] = {
        /* device interface */
        DEVMETHOD(device_probe,         miiproxy_probe),
        DEVMETHOD(device_attach,        miiproxy_attach),
        DEVMETHOD(device_detach,        miiproxy_detach),
        DEVMETHOD(device_shutdown,      bus_generic_shutdown),

        /* MII interface */
        DEVMETHOD(miibus_readreg,       miiproxy_readreg),
        DEVMETHOD(miibus_writereg,      miiproxy_writereg),
        DEVMETHOD(miibus_statchg,       miiproxy_statchg),
        DEVMETHOD(miibus_linkchg,       miiproxy_linkchg),
        DEVMETHOD(miibus_mediainit,     miiproxy_mediainit),

        DEVMETHOD_END
};

static device_method_t mdioproxy_methods[] = {
        /* device interface */
        DEVMETHOD(device_identify,      mdioproxy_identify),
        DEVMETHOD(device_probe,         mdioproxy_probe),
        DEVMETHOD(device_attach,        mdioproxy_attach),
        DEVMETHOD(device_detach,        mdioproxy_detach),
        DEVMETHOD(device_shutdown,      bus_generic_shutdown),

        DEVMETHOD_END
};

DEFINE_CLASS_0(miiproxy, miiproxy_driver, miiproxy_methods,
    sizeof(struct miiproxy_softc));
DEFINE_CLASS_0(mdioproxy, mdioproxy_driver, mdioproxy_methods,
    sizeof(struct mdioproxy_softc));

DRIVER_MODULE(mdioproxy, mdio, mdioproxy_driver, 0, 0);
DRIVER_MODULE(miibus, miiproxy, miibus_driver, 0, 0);
MODULE_VERSION(miiproxy, 1);
MODULE_DEPEND(miiproxy, miibus, 1, 1, 1);
MODULE_DEPEND(miiproxy, mdio, 1, 1, 1);