/*-
 * Copyright 1998 Massachusetts Institute of Technology
 * Copyright 2001 by Thomas Moestl <tmm@FreeBSD.org>.
 * Copyright 2006 by Marius Strobl <marius@FreeBSD.org>.
 * All rights reserved.
 *
 * Permission to use, copy, modify, and distribute this software and
 * its documentation for any purpose and without fee is hereby
 * granted, provided that both the above copyright notice and this
 * permission notice appear in all copies, that both the above
 * copyright notice and this permission notice appear in all
 * supporting documentation, and that the name of M.I.T. not be used
 * in advertising or publicity pertaining to distribution of the
 * software without specific, written prior permission.  M.I.T. makes
 * no representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied
 * warranty.
 *
 * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''.  M.I.T. DISCLAIMS
 * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
 * SHALL M.I.T. 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.
 *
 *      from: FreeBSD: src/sys/i386/i386/nexus.c,v 1.43 2001/02/09
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/rman.h>

#include <dev/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>
#include <dev/ofw/openfirm.h>
#include <dev/fdt/simplebus.h>

#include <machine/bus.h>
#include <machine/resource.h>

/*
 * The ofwbus (which is a pseudo-bus actually) iterates over the nodes that
 * hang from the Open Firmware root node and adds them as devices to this bus
 * (except some special nodes which are excluded) so that drivers can be
 * attached to them. There should be only one ofwbus in the system, added
 * directly as a child of nexus0.
 */

static device_probe_t ofwbus_probe;
static device_attach_t ofwbus_attach;
static bus_alloc_resource_t ofwbus_alloc_resource;
static bus_release_resource_t ofwbus_release_resource;

static device_method_t ofwbus_methods[] = {
        /* Device interface */
        DEVMETHOD(device_probe,         ofwbus_probe),
        DEVMETHOD(device_attach,        ofwbus_attach),

        /* Bus interface */
        DEVMETHOD(bus_alloc_resource,   ofwbus_alloc_resource),
        DEVMETHOD(bus_adjust_resource,  bus_generic_adjust_resource),
        DEVMETHOD(bus_release_resource, ofwbus_release_resource),

        DEVMETHOD_END
};

DEFINE_CLASS_1(ofwbus, ofwbus_driver, ofwbus_methods,
    sizeof(struct simplebus_softc), simplebus_driver);
EARLY_DRIVER_MODULE(ofwbus, nexus, ofwbus_driver, 0, 0,
    BUS_PASS_BUS + BUS_PASS_ORDER_MIDDLE);
MODULE_VERSION(ofwbus, 1);

static int
ofwbus_probe(device_t dev)
{

        if (OF_peer(0) == 0)
                return (ENXIO);

        /* Only one instance of ofwbus. */
        if (device_get_unit(dev) != 0)
                panic("ofwbus added with non-zero unit number: %d\n",
                    device_get_unit(dev));

        device_set_desc(dev, "Open Firmware Device Tree");
        return (BUS_PROBE_NOWILDCARD);
}

static int
ofwbus_attach(device_t dev)
{
        phandle_t node;

        node = OF_peer(0);

        /*
         * If no Open Firmware, bail early
         */
        if (node == -1)
                return (ENXIO);

        /*
         * ofwbus bus starts on unamed node in FDT, so we cannot make
         * ofw_bus_devinfo from it. Pass node to simplebus_init directly.
         */
        simplebus_init(dev, node);

        /*
         * Allow devices to identify.
         */
        bus_identify_children(dev);

        /*
         * Now walk the OFW tree and attach top-level devices.
         */
        for (node = OF_child(node); node > 0; node = OF_peer(node))
                simplebus_add_device(dev, node, 0, NULL, -1, NULL);

        bus_attach_children(dev);
        return (0);
}

static struct resource *
ofwbus_alloc_resource(device_t bus, device_t child, int type, int rid,
    rman_res_t start, rman_res_t end, rman_res_t count, u_int flags)
{
        struct resource *rv;
        struct resource_list_entry *rle;
        bool isdefault, passthrough;

        isdefault = RMAN_IS_DEFAULT_RANGE(start, end);
        passthrough = (device_get_parent(child) != bus);
        rle = NULL;
        if (!passthrough && isdefault) {
                rle = resource_list_find(BUS_GET_RESOURCE_LIST(bus, child),
                    type, rid);
                if (rle == NULL) {
                        if (bootverbose)
                                device_printf(bus, "no default resources for "
                                    "rid = %d, type = %d\n", rid, type);
                        return (NULL);
                }
                start = rle->start;
                count = ummax(count, rle->count);
                end = ummax(rle->end, start + count - 1);
        }

        /* Let nexus handle the allocation. */
        rv = bus_generic_alloc_resource(bus, child, type, rid, start, end,
            count, flags);
        if (rv == NULL)
                return (NULL);

        if (!passthrough && rle != NULL) {
                rle->res = rv;
                rle->start = rman_get_start(rv);
                rle->end = rman_get_end(rv);
                rle->count = rle->end - rle->start + 1;
        }

        return (rv);
}

static int
ofwbus_release_resource(device_t bus, device_t child, struct resource *r)
{
        struct resource_list_entry *rle;
        bool passthrough;

        passthrough = (device_get_parent(child) != bus);
        if (!passthrough) {
                /* Clean resource list entry */
                rle = resource_list_find(BUS_GET_RESOURCE_LIST(bus, child),
                    rman_get_type(r), rman_get_rid(r));
                if (rle != NULL)
                        rle->res = NULL;
        }

        /* Let nexus handle the release. */
        return (bus_generic_release_resource(bus, child, r));
}