/*-
 * Copyright (C) 2015 Nathan Whitehorn
 * 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 ``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 <machine/asm.h>

#include "opt_platform.h"

GLOBAL(opal_entrypoint)
        .llong  0
GLOBAL(opal_data)
        .llong  0
GLOBAL(opal_msr)
        .llong  0

TOC_ENTRY(opal_entrypoint)
TOC_ENTRY(opal_data)
TOC_ENTRY(opal_msr)

ASENTRY(opal_call)
        /* Args:
         * r3: opal token
         * r4-r10 opal arguments
         */

        /* Save call stuff on stack */
        mflr    %r0
        std     %r0,16(%r1)
        std     %r2,-16(%r1)
        mfcr    %r0
        std     %r0,8(%r1)

        /* Load OPAL entry information */
        mr      %r0,%r3
        addis   %r3,%r2,TOC_REF(opal_entrypoint)@ha
        ld      %r3,TOC_REF(opal_entrypoint)@l(%r3)
        ld      %r3,0(%r3)
        mtctr   %r3

        /* Save MSR in non-volatile scratch register and turn off translation */
        std     %r31,-8(%r1)
        mfmsr   %r31

        /* Load last bits from the TOC */
        addis   %r3,%r2,TOC_REF(opal_msr)@ha
        ld      %r3,TOC_REF(opal_msr)@l(%r3)
        ld      %r3,0(%r3)
        addis   %r2,%r2,TOC_REF(opal_data)@ha
        ld      %r2,TOC_REF(opal_data)@l(%r2)
        ld      %r2,0(%r2)


#if defined(__LITTLE_ENDIAN__) && defined(QEMU)
        /* QEMU hack: qemu does not emulate mtmsrd correctly! */
        ori     %r3,%r3,1       /* Leave PSR_LE set */
#endif
        mtmsrd  %r3
        isync
#if defined(__LITTLE_ENDIAN__) && defined(QEMU)
        /* Clean up from qemu hack */
        xori    %r3,%r3,1
#endif

#ifdef __LITTLE_ENDIAN__
        mtsrr1  %r3
#endif

        /* Shift registers over */
        mr      %r3,%r4
        mr      %r4,%r5
        mr      %r5,%r6
        mr      %r6,%r7
        mr      %r7,%r8
        mr      %r8,%r9
        mr      %r9,%r10

#ifdef __LITTLE_ENDIAN__
        /* We need to rfid to switch endian. */
        mfctr   %r11
        mtsrr0  %r11
        LOAD_LR_NIA
1:
        mflr    %r11
        addi    %r11, %r11, (2f-1b)
        mtlr    %r11
        /* Call OPAL */
        rfid
2:
        RETURN_TO_NATIVE_ENDIAN
#else
        /* Call OPAL */
        bctrl
#endif

        /* Restore MSR */
        mtmsrd  %r31
        isync
        ld      %r31,-8(%r1)
        
        /* Restore call stuff from stack */
        ld      %r0,16(%r1)
        mtlr    %r0
        ld      %r2,-16(%r1)
        ld      %r0,8(%r1)
        mtcr    %r0

        /* And return */
        blr
ASEND(opal_call)