/*      $NetBSD: Locore.c,v 1.7 2000/08/20 07:04:59 tsubai Exp $        */

/*-
 * SPDX-License-Identifier:BSD-4-Clause AND BSD-2-Clause
 *
 * Copyright (C) 1995, 1996 Wolfgang Solfrank.
 * Copyright (C) 1995, 1996 TooLs GmbH.
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by TooLs GmbH.
 * 4. The name of TooLs GmbH may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``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 TOOLS GMBH 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.
 */
/*-
 * Copyright (C) 2000 Benno Rice.
 * 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 Benno Rice ``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 TOOLS GMBH 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/cdefs.h>
#include <sys/endian.h>
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/stdarg.h>
#include <sys/systm.h>

#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/pmap.h>

#include <machine/bus.h>
#include <machine/md_var.h>
#include <machine/ofw_machdep.h>

#include <dev/ofw/openfirm.h>
#include <dev/ofw/ofwvar.h>
#include "ofw_if.h"

static int ofw_real_init(ofw_t, void *openfirm);
static int ofw_real_test(ofw_t, const char *name);
static phandle_t ofw_real_peer(ofw_t, phandle_t node);
static phandle_t ofw_real_child(ofw_t, phandle_t node);
static phandle_t ofw_real_parent(ofw_t, phandle_t node);
static phandle_t ofw_real_instance_to_package(ofw_t, ihandle_t instance);
static ssize_t ofw_real_getproplen(ofw_t, phandle_t package, 
    const char *propname);
static ssize_t ofw_real_getprop(ofw_t, phandle_t package, const char *propname, 
    void *buf, size_t buflen);
static int ofw_real_nextprop(ofw_t, phandle_t package, const char *previous, 
    char *buf, size_t);
static int ofw_real_setprop(ofw_t, phandle_t package, const char *propname,
    const void *buf, size_t len);
static ssize_t ofw_real_canon(ofw_t, const char *device, char *buf, size_t len);
static phandle_t ofw_real_finddevice(ofw_t, const char *device);
static ssize_t ofw_real_instance_to_path(ofw_t, ihandle_t instance, char *buf, 
    size_t len);
static ssize_t ofw_real_package_to_path(ofw_t, phandle_t package, char *buf, 
    size_t len);
static int ofw_real_call_method(ofw_t, ihandle_t instance, const char *method, 
    int nargs, int nreturns, cell_t *args_and_returns);
static int ofw_real_interpret(ofw_t ofw, const char *cmd, int nreturns,
    cell_t *returns);
static ihandle_t ofw_real_open(ofw_t, const char *device);
static void ofw_real_close(ofw_t, ihandle_t instance);
static ssize_t ofw_real_read(ofw_t, ihandle_t instance, void *addr, size_t len);
static ssize_t ofw_real_write(ofw_t, ihandle_t instance, const void *addr, 
    size_t len);
static int ofw_real_seek(ofw_t, ihandle_t instance, u_int64_t pos);
static caddr_t ofw_real_claim(ofw_t, void *virt, size_t size, u_int align);
static void ofw_real_release(ofw_t, void *virt, size_t size);
static void ofw_real_enter(ofw_t);
static void ofw_real_exit(ofw_t);

static ofw_method_t ofw_real_methods[] = {
        OFWMETHOD(ofw_init,                     ofw_real_init),
        OFWMETHOD(ofw_peer,                     ofw_real_peer),
        OFWMETHOD(ofw_child,                    ofw_real_child),
        OFWMETHOD(ofw_parent,                   ofw_real_parent),
        OFWMETHOD(ofw_instance_to_package,      ofw_real_instance_to_package),
        OFWMETHOD(ofw_getproplen,               ofw_real_getproplen),
        OFWMETHOD(ofw_getprop,                  ofw_real_getprop),
        OFWMETHOD(ofw_nextprop,                 ofw_real_nextprop),
        OFWMETHOD(ofw_setprop,                  ofw_real_setprop),
        OFWMETHOD(ofw_canon,                    ofw_real_canon),
        OFWMETHOD(ofw_finddevice,               ofw_real_finddevice),
        OFWMETHOD(ofw_instance_to_path,         ofw_real_instance_to_path),
        OFWMETHOD(ofw_package_to_path,          ofw_real_package_to_path),

        OFWMETHOD(ofw_test,                     ofw_real_test),
        OFWMETHOD(ofw_call_method,              ofw_real_call_method),
        OFWMETHOD(ofw_interpret,                ofw_real_interpret),
        OFWMETHOD(ofw_open,                     ofw_real_open),
        OFWMETHOD(ofw_close,                    ofw_real_close),
        OFWMETHOD(ofw_read,                     ofw_real_read),
        OFWMETHOD(ofw_write,                    ofw_real_write),
        OFWMETHOD(ofw_seek,                     ofw_real_seek),
        OFWMETHOD(ofw_claim,                    ofw_real_claim),
        OFWMETHOD(ofw_release,                  ofw_real_release),
        OFWMETHOD(ofw_enter,                    ofw_real_enter),
        OFWMETHOD(ofw_exit,                     ofw_real_exit),
        { 0, 0 }
};

static ofw_def_t ofw_real = {
        OFW_STD_REAL,
        ofw_real_methods,
        0
};
OFW_DEF(ofw_real);

static ofw_def_t ofw_32bit = {
        OFW_STD_32BIT,
        ofw_real_methods,
        0
};
OFW_DEF(ofw_32bit);

static MALLOC_DEFINE(M_OFWREAL, "ofwreal",
    "Open Firmware Real Mode Bounce Page");

static int (*openfirmware)(void *);

static vm_offset_t      of_bounce_phys;
static caddr_t          of_bounce_virt;
static off_t            of_bounce_offset;
static size_t           of_bounce_size;

#define IN(x) htobe32(x)
#define OUT(x) be32toh(x)

/*
 * To be able to use OFW console on PPC, that requires real mode OFW,
 * the mutex that guards the mapping/unmapping of virtual to physical
 * buffers (of_real_mtx) must be of SPIN type. This is needed because
 * kernel console first locks a SPIN mutex before calling OFW real.
 * By default, of_real_mtx is a sleepable mutex. To make it of SPIN
 * type, use the following tunnable:
 * machdep.ofw.mtx_spin=1
 *
 * Besides that, a few more tunables are needed to select and use the
 * OFW console with real mode OFW.
 *
 * In order to disable the use of OFW FrameBuffer and fallback to the
 * OFW console, use:
 * hw.ofwfb.disable=1
 *
 * To disable the use of FDT (that doesn't support OFW read/write methods)
 * and use real OFW instead, unset the following loader variable:
 * unset usefdt
 *
 * OFW is put in quiesce state in early kernel boot, which usually disables
 * OFW read/write capabilities (in QEMU write continue to work, but
 * read doesn't). To avoid OFW quiesce, use:
 * debug.quiesce_ofw=0
 *
 * Note that disabling OFW quiesce can cause conflicts between kernel and
 * OFW trying to control the same hardware. Thus, it must be used with care.
 * Some conflicts can be avoided by disabling kernel drivers with hints.
 * For instance, to disable a xhci controller and an USB keyboard connected
 * to it, that may be already being used for input by OFW, use:
 * hint.xhci.0.disabled=1
 */

static struct mtx       of_bounce_mtx;
static struct mtx       of_spin_mtx;
static struct mtx       *of_real_mtx;
static void             (*of_mtx_lock)(void);
static void             (*of_mtx_unlock)(void);

extern int              ofw_real_mode;

/*
 * After the VM is up, allocate a wired, low memory bounce page.
 */

static void ofw_real_bounce_alloc(void *);

SYSINIT(ofw_real_bounce_alloc, SI_SUB_KMEM, SI_ORDER_ANY, 
    ofw_real_bounce_alloc, NULL);

static void
ofw_real_mtx_lock_spin(void)
{
        mtx_lock_spin(of_real_mtx);
}

static void
ofw_real_mtx_lock(void)
{
        mtx_lock(of_real_mtx);
}

static void
ofw_real_mtx_unlock_spin(void)
{
        mtx_unlock_spin(of_real_mtx);
}

static void
ofw_real_mtx_unlock(void)
{
        mtx_unlock(of_real_mtx);
}

static void
ofw_real_start(void)
{
        (*of_mtx_lock)();
        of_bounce_offset = 0;
}

static void
ofw_real_stop(void)
{
        (*of_mtx_unlock)();
}

static void
ofw_real_bounce_alloc(void *junk)
{
        caddr_t temp;

        /*
         * Check that ofw_real is actually in use before allocating wads 
         * of memory. Do this by checking if our mutex has been set up.
         */
        if (!mtx_initialized(&of_bounce_mtx))
                return;

        /*
         * Allocate a page of contiguous, wired physical memory that can
         * fit into a 32-bit address space and accessed from real mode.
         */
        temp = contigmalloc(4 * PAGE_SIZE, M_OFWREAL, 0, 0,
            ulmin(platform_real_maxaddr(), BUS_SPACE_MAXADDR_32BIT), PAGE_SIZE,
            4 * PAGE_SIZE);
        if (temp == NULL)
                panic("%s: Not able to allocated contiguous memory\n", __func__);

        mtx_lock(&of_bounce_mtx);

        of_bounce_virt = temp;

        of_bounce_phys = vtophys(of_bounce_virt);
        of_bounce_size = 4 * PAGE_SIZE;

        /*
         * For virtual-mode OF, direct map this physical address so that
         * we have a 32-bit virtual address to give OF.
         */

        if (!ofw_real_mode && (!hw_direct_map || DMAP_BASE_ADDRESS != 0))
                pmap_kenter(of_bounce_phys, of_bounce_phys);

        mtx_unlock(&of_bounce_mtx);
}

static cell_t
ofw_real_map(const void *buf, size_t len)
{
        static char emergency_buffer[255];
        cell_t phys;

        mtx_assert(of_real_mtx, MA_OWNED);

        if (of_bounce_virt == NULL) {
                /*
                 * If we haven't set up the MMU, then buf is guaranteed
                 * to be accessible to OF, because the only memory we
                 * can use right now is memory mapped by firmware.
                 */
                if (!pmap_bootstrapped)
                        return (cell_t)((uintptr_t)buf & ~DMAP_BASE_ADDRESS);

                /*
                 * XXX: It is possible for us to get called before the VM has
                 * come online, but after the MMU is up. We don't have the
                 * bounce buffer yet, but can no longer presume a 1:1 mapping.
                 * Copy into the emergency buffer, and reset at the end.
                 */
                of_bounce_virt = emergency_buffer;
                of_bounce_phys = (vm_offset_t)of_bounce_virt &
                    ~DMAP_BASE_ADDRESS;
                of_bounce_size = sizeof(emergency_buffer);
        }

        /*
         * Make sure the bounce page offset satisfies any reasonable
         * alignment constraint.
         */
        of_bounce_offset += sizeof(register_t) -
            (of_bounce_offset % sizeof(register_t));

        if (of_bounce_offset + len > of_bounce_size) {
                panic("Oversize Open Firmware call!");
                return 0;
        }

        if (buf != NULL)
                memcpy(of_bounce_virt + of_bounce_offset, buf, len);
        else
                return (0);

        phys = of_bounce_phys + of_bounce_offset;

        of_bounce_offset += len;

        return (phys);
}

static void
ofw_real_unmap(cell_t physaddr, void *buf, size_t len)
{
        mtx_assert(of_real_mtx, MA_OWNED);

        if (of_bounce_virt == NULL)
                return;

        if (physaddr == 0)
                return;

        memcpy(buf,of_bounce_virt + (physaddr - of_bounce_phys),len);
}

/* Initialiser */

static int
ofw_real_init(ofw_t ofw, void *openfirm)
{
        int mtx_spin;

        openfirmware = (int (*)(void *))openfirm;
        mtx_init(&of_bounce_mtx, "OF Bounce Page", NULL, MTX_DEF);

        mtx_spin = 0;
        TUNABLE_INT_FETCH("machdep.ofw.mtx_spin", &mtx_spin);
        if (mtx_spin) {
                mtx_init(&of_spin_mtx, "OF Real", NULL, MTX_SPIN);
                of_real_mtx = &of_spin_mtx;
                of_mtx_lock = ofw_real_mtx_lock_spin;
                of_mtx_unlock = ofw_real_mtx_unlock_spin;
        } else {
                of_real_mtx = &of_bounce_mtx;
                of_mtx_lock = ofw_real_mtx_lock;
                of_mtx_unlock = ofw_real_mtx_unlock;
        }

        of_bounce_virt = NULL;
        return (0);
}

/*
 * Generic functions
 */

/* Test to see if a service exists. */
static int
ofw_real_test(ofw_t ofw, const char *name)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t service;
                cell_t missing;
        } args;

        args.name = IN((cell_t)(uintptr_t)"test");
        args.nargs = IN(1);
        args.nreturns = IN(1);

        ofw_real_start();

        args.service = IN(ofw_real_map(name, strlen(name) + 1));
        argsptr = ofw_real_map(&args, sizeof(args));
        if (args.service == 0 || openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return (-1);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_stop();
        return (OUT(args.missing));
}

/*
 * Device tree functions
 */

/* Return the next sibling of this node or 0. */
static phandle_t
ofw_real_peer(ofw_t ofw, phandle_t node)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t node;
                cell_t next;
        } args;

        args.name = IN((cell_t)(uintptr_t)"peer");
        args.nargs = IN(1);
        args.nreturns = IN(1);

        args.node = IN(node);
        ofw_real_start();
        argsptr = ofw_real_map(&args, sizeof(args));
        if (openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return (0);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_stop();
        return (OUT(args.next));
}

/* Return the first child of this node or 0. */
static phandle_t
ofw_real_child(ofw_t ofw, phandle_t node)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t node;
                cell_t child;
        } args;

        args.name = IN((cell_t)(uintptr_t)"child");
        args.nargs = IN(1);
        args.nreturns = IN(1);

        args.node = IN(node);
        ofw_real_start();
        argsptr = ofw_real_map(&args, sizeof(args));
        if (openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return (0);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_stop();
        return (OUT(args.child));
}

/* Return the parent of this node or 0. */
static phandle_t
ofw_real_parent(ofw_t ofw, phandle_t node)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t node;
                cell_t parent;
        } args;

        args.name = IN((cell_t)(uintptr_t)"parent");
        args.nargs = IN(1);
        args.nreturns = IN(1);

        args.node = IN(node);
        ofw_real_start();
        argsptr = ofw_real_map(&args, sizeof(args));
        if (openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return (0);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_stop();
        return (OUT(args.parent));
}

/* Return the package handle that corresponds to an instance handle. */
static phandle_t
ofw_real_instance_to_package(ofw_t ofw, ihandle_t instance)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t instance;
                cell_t package;
        } args;

        args.name = IN((cell_t)(uintptr_t)"instance-to-package");
        args.nargs = IN(1);
        args.nreturns = IN(1);

        args.instance = IN(instance);
        ofw_real_start();
        argsptr = ofw_real_map(&args, sizeof(args));
        if (openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return (-1);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_stop();
        return (OUT(args.package));
}

/* Get the length of a property of a package. */
static ssize_t
ofw_real_getproplen(ofw_t ofw, phandle_t package, const char *propname)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t package;
                cell_t propname;
                int32_t proplen;
        } args;

        args.name = IN((cell_t)(uintptr_t)"getproplen");
        args.nargs = IN(2);
        args.nreturns = IN(1);

        ofw_real_start();

        args.package = IN(package);
        args.propname = IN(ofw_real_map(propname, strlen(propname) + 1));
        argsptr = ofw_real_map(&args, sizeof(args));
        if (args.propname == 0 || openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return (-1);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_stop();
        return ((ssize_t)(int32_t)OUT(args.proplen));
}

/* Get the value of a property of a package. */
static ssize_t
ofw_real_getprop(ofw_t ofw, phandle_t package, const char *propname, void *buf, 
    size_t buflen)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t package;
                cell_t propname;
                cell_t buf;
                cell_t buflen;
                int32_t size;
        } args;

        args.name = IN((cell_t)(uintptr_t)"getprop");
        args.nargs = IN(4);
        args.nreturns = IN(1);

        ofw_real_start();

        args.package = IN(package);
        args.propname = IN(ofw_real_map(propname, strlen(propname) + 1));
        args.buf = IN(ofw_real_map(buf, buflen));
        args.buflen = IN(buflen);
        argsptr = ofw_real_map(&args, sizeof(args));
        if (args.propname == 0 || args.buf == 0 ||
            openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return (-1);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_unmap(OUT(args.buf), buf, buflen);

        ofw_real_stop();
        return ((ssize_t)(int32_t)OUT(args.size));
}

/* Get the next property of a package. */
static int
ofw_real_nextprop(ofw_t ofw, phandle_t package, const char *previous, 
    char *buf, size_t size)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t package;
                cell_t previous;
                cell_t buf;
                cell_t flag;
        } args;

        args.name = IN((cell_t)(uintptr_t)"nextprop");
        args.nargs = IN(3);
        args.nreturns = IN(1);

        ofw_real_start();

        args.package = IN(package);
        args.previous = IN(ofw_real_map(previous, (previous != NULL) ? (strlen(previous) + 1) : 0));
        args.buf = IN(ofw_real_map(buf, size));
        argsptr = ofw_real_map(&args, sizeof(args));
        if (args.buf == 0 || openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return (-1);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_unmap(OUT(args.buf), buf, size);

        ofw_real_stop();
        return (OUT(args.flag));
}

/* Set the value of a property of a package. */
/* XXX Has a bug on FirePower */
static int
ofw_real_setprop(ofw_t ofw, phandle_t package, const char *propname,
    const void *buf, size_t len)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t package;
                cell_t propname;
                cell_t buf;
                cell_t len;
                cell_t size;
        } args;

        args.name = IN((cell_t)(uintptr_t)"setprop");
        args.nargs = IN(4);
        args.nreturns = IN(1);

        ofw_real_start();

        args.package = IN(package);
        args.propname = IN(ofw_real_map(propname, strlen(propname) + 1));
        args.buf = IN(ofw_real_map(buf, len));
        args.len = IN(len);
        argsptr = ofw_real_map(&args, sizeof(args));
        if (args.propname == 0 || args.buf == 0 ||
            openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return (-1);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_stop();
        return (OUT(args.size));
}

/* Convert a device specifier to a fully qualified pathname. */
static ssize_t
ofw_real_canon(ofw_t ofw, const char *device, char *buf, size_t len)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t device;
                cell_t buf;
                cell_t len;
                int32_t size;
        } args;

        args.name = IN((cell_t)(uintptr_t)"canon");
        args.nargs = IN(3);
        args.nreturns = IN(1);

        ofw_real_start();

        args.device = IN(ofw_real_map(device, strlen(device) + 1));
        args.buf = IN(ofw_real_map(buf, len));
        args.len = IN(len);
        argsptr = ofw_real_map(&args, sizeof(args));
        if (args.device == 0 || args.buf == 0 ||
            openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return (-1);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_unmap(OUT(args.buf), buf, len);

        ofw_real_stop();
        return ((ssize_t)(int32_t)OUT(args.size));
}

/* Return a package handle for the specified device. */
static phandle_t
ofw_real_finddevice(ofw_t ofw, const char *device)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t device;
                cell_t package;
        } args;

        args.name = IN((cell_t)(uintptr_t)"finddevice");
        args.nargs = IN(1);
        args.nreturns = IN(1);

        ofw_real_start();

        args.device = IN(ofw_real_map(device, strlen(device) + 1));
        argsptr = ofw_real_map(&args, sizeof(args));
        if (args.device == 0 ||
            openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return (-1);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_stop();
        return (OUT(args.package));
}

/* Return the fully qualified pathname corresponding to an instance. */
static ssize_t
ofw_real_instance_to_path(ofw_t ofw, ihandle_t instance, char *buf, size_t len)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t instance;
                cell_t buf;
                cell_t len;
                int32_t size;
        } args;

        args.name = IN((cell_t)(uintptr_t)"instance-to-path");
        args.nargs = IN(3);
        args.nreturns = IN(1);

        ofw_real_start();

        args.instance = IN(instance);
        args.buf = IN(ofw_real_map(buf, len));
        args.len = IN(len);
        argsptr = ofw_real_map(&args, sizeof(args));
        if (args.buf == 0 ||
            openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return (-1);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_unmap(OUT(args.buf), buf, len);

        ofw_real_stop();
        return ((ssize_t)(int32_t)OUT(args.size));
}

/* Return the fully qualified pathname corresponding to a package. */
static ssize_t
ofw_real_package_to_path(ofw_t ofw, phandle_t package, char *buf, size_t len)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t package;
                cell_t buf;
                cell_t len;
                int32_t size;
        } args;

        args.name = IN((cell_t)(uintptr_t)"package-to-path");
        args.nargs = IN(3);
        args.nreturns = IN(1);

        ofw_real_start();

        args.package = IN(package);
        args.buf = IN(ofw_real_map(buf, len));
        args.len = IN(len);
        argsptr = ofw_real_map(&args, sizeof(args));
        if (args.buf == 0 ||
            openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return (-1);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_unmap(OUT(args.buf), buf, len);

        ofw_real_stop();
        return ((ssize_t)(int32_t)OUT(args.size));
}

/*  Call the method in the scope of a given instance. */
static int
ofw_real_call_method(ofw_t ofw, ihandle_t instance, const char *method, 
    int nargs, int nreturns, cell_t *args_and_returns)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t method;
                cell_t instance;
                cell_t args_n_results[12];
        } args;
        cell_t *ap, *cp;
        int n;

        args.name = IN((cell_t)(uintptr_t)"call-method");
        args.nargs = IN(2);
        args.nreturns = IN(1);

        if (nargs > 6)
                return (-1);

        ofw_real_start();
        args.nargs = IN(nargs + 2);
        args.nreturns = IN(nreturns + 1);
        args.method = IN(ofw_real_map(method, strlen(method) + 1));
        args.instance = IN(instance);

        ap = args_and_returns;
        for (cp = args.args_n_results + (n = nargs); --n >= 0;)
                *--cp = IN(*(ap++));
        argsptr = ofw_real_map(&args, sizeof(args));
        if (args.method == 0 ||
            openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return (-1);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_stop();
        if (OUT(args.args_n_results[nargs]))
                return (OUT(args.args_n_results[nargs]));
        for (cp = args.args_n_results + nargs + (n = OUT(args.nreturns)); --n > 0;)
                *(ap++) = OUT(*--cp);
        return (0);
}

static int
ofw_real_interpret(ofw_t ofw, const char *cmd, int nreturns, cell_t *returns)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t slot[16];
        } args;
        cell_t status;
        int i = 0, j = 0;

        args.name = IN((cell_t)(uintptr_t)"interpret");
        args.nargs = IN(1);

        ofw_real_start();
        args.nreturns = IN(++nreturns);
        args.slot[i++] = IN(ofw_real_map(cmd, strlen(cmd) + 1));
        argsptr = ofw_real_map(&args, sizeof(args));
        if (openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return (-1);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_stop();
        status = OUT(args.slot[i++]);
        while (i < 1 + nreturns)
                returns[j++] = OUT(args.slot[i++]);
        return (status);
}

/*
 * Device I/O functions
 */

/* Open an instance for a device. */
static ihandle_t
ofw_real_open(ofw_t ofw, const char *device)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t device;
                cell_t instance;
        } args;

        args.name = IN((cell_t)(uintptr_t)"open");
        args.nargs = IN(1);
        args.nreturns = IN(1);

        ofw_real_start();

        args.device = IN(ofw_real_map(device, strlen(device) + 1));
        argsptr = ofw_real_map(&args, sizeof(args));
        if (args.device == 0 || openfirmware((void *)argsptr) == -1 
            || args.instance == 0) {
                ofw_real_stop();
                return (-1);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_stop();
        return (OUT(args.instance));
}

/* Close an instance. */
static void
ofw_real_close(ofw_t ofw, ihandle_t instance)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t instance;
        } args;

        args.name = IN((cell_t)(uintptr_t)"close");
        args.nargs = IN(1);
        args.nreturns = IN(0);
        args.instance = IN(instance);
        ofw_real_start();
        argsptr = ofw_real_map(&args, sizeof(args));
        openfirmware((void *)argsptr);
        ofw_real_stop();
}

/* Read from an instance. */
static ssize_t
ofw_real_read(ofw_t ofw, ihandle_t instance, void *addr, size_t len)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t instance;
                cell_t addr;
                cell_t len;
                int32_t actual;
        } args;

        args.name = IN((cell_t)(uintptr_t)"read");
        args.nargs = IN(3);
        args.nreturns = IN(1);

        ofw_real_start();

        args.instance = IN(instance);
        args.addr = IN(ofw_real_map(addr, len));
        args.len = IN(len);
        argsptr = ofw_real_map(&args, sizeof(args));
        if (args.addr == 0 || openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return (-1);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_unmap(OUT(args.addr), addr, len);

        ofw_real_stop();
        return ((ssize_t)(int32_t)OUT(args.actual));
}

/* Write to an instance. */
static ssize_t
ofw_real_write(ofw_t ofw, ihandle_t instance, const void *addr, size_t len)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t instance;
                cell_t addr;
                cell_t len;
                int32_t actual;
        } args;

        args.name = IN((cell_t)(uintptr_t)"write");
        args.nargs = IN(3);
        args.nreturns = IN(1);

        ofw_real_start();

        args.instance = IN(instance);
        args.addr = IN(ofw_real_map(addr, len));
        args.len = IN(len);
        argsptr = ofw_real_map(&args, sizeof(args));
        if (args.addr == 0 || openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return (-1);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_stop();
        return ((ssize_t)(int32_t)OUT(args.actual));
}

/* Seek to a position. */
static int
ofw_real_seek(ofw_t ofw, ihandle_t instance, u_int64_t pos)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t instance;
                cell_t poshi;
                cell_t poslo;
                cell_t status;
        } args;

        args.name = IN((cell_t)(uintptr_t)"seek");
        args.nargs = IN(3);
        args.nreturns = IN(1);

        args.instance = IN(instance);
        args.poshi = IN(pos >> 32);
        args.poslo = IN(pos);
        ofw_real_start();
        argsptr = ofw_real_map(&args, sizeof(args));
        if (openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return (-1);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_stop();
        return (OUT(args.status));
}

/*
 * Memory functions
 */

/* Claim an area of memory. */
static caddr_t
ofw_real_claim(ofw_t ofw, void *virt, size_t size, u_int align)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t virt;
                cell_t size;
                cell_t align;
                cell_t baseaddr;
        } args;

        args.name = IN((cell_t)(uintptr_t)"claim");
        args.nargs = IN(3);
        args.nreturns = IN(1);

        args.virt = IN((cell_t)(uintptr_t)virt);
        args.size = IN(size);
        args.align = IN(align);
        ofw_real_start();
        argsptr = ofw_real_map(&args, sizeof(args));
        if (openfirmware((void *)argsptr) == -1) {
                ofw_real_stop();
                return ((void *)-1);
        }
        ofw_real_unmap(argsptr, &args, sizeof(args));
        ofw_real_stop();
        return ((void *)(uintptr_t)(OUT(args.baseaddr)));
}

/* Release an area of memory. */
static void
ofw_real_release(ofw_t ofw, void *virt, size_t size)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
                cell_t virt;
                cell_t size;
        } args;

        args.name = IN((cell_t)(uintptr_t)"release");
        args.nargs = IN(2);
        args.nreturns = IN(0);

        args.virt = IN((cell_t)(uintptr_t)virt);
        args.size = IN(size);
        ofw_real_start();
        argsptr = ofw_real_map(&args, sizeof(args));
        openfirmware((void *)argsptr);
        ofw_real_stop();
}

/*
 * Control transfer functions
 */

/* Suspend and drop back to the Open Firmware interface. */
static void
ofw_real_enter(ofw_t ofw)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
        } args;

        args.name = IN((cell_t)(uintptr_t)"enter");
        args.nargs = IN(0);
        args.nreturns = IN(0);

        ofw_real_start();
        argsptr = ofw_real_map(&args, sizeof(args));
        openfirmware((void *)argsptr);
        /* We may come back. */
        ofw_real_stop();
}

/* Shut down and drop back to the Open Firmware interface. */
static void
ofw_real_exit(ofw_t ofw)
{
        vm_offset_t argsptr;
        struct {
                cell_t name;
                cell_t nargs;
                cell_t nreturns;
        } args;

        args.name = IN((cell_t)(uintptr_t)"exit");
        args.nargs = IN(0);
        args.nreturns = IN(0);

        ofw_real_start();
        argsptr = ofw_real_map(&args, sizeof(args));
        openfirmware((void *)argsptr);
        for (;;)                        /* just in case */
                ;
        ofw_real_stop();
}