/*-
 * Copyright (c) 2007 Semihalf, Rafal Jaworowski <raj@semihalf.com>
 * 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 <machine/asm.h>

/*
 * Entry point to the loader that U-Boot passes control to.
 */
        .text
        .globl  _start
_start:
        /* Hint where to look for the API signature */
        lis     %r11, uboot_address@ha
        addi    %r11, %r11, uboot_address@l
        stw     %r1, 0(%r11)
        /* Save U-Boot's r14 and r30 */
        lis     %r11, saved_regs@ha
        addi    %r11, %r11, saved_regs@l
        stw     %r14, 0(%r11)
        stw     %r30, 4(%r11)
        /* Disable interrupts */
        mfmsr   %r11
        andi.   %r11, %r11, ~0x8000@l
        mtmsr   %r11
        b       main

/*
 * syscall()
 */
ENTRY(syscall)
        stwu    %r1, -32(%r1)
        mflr    %r0
        stw     %r14, 8(%r1)
        stw     %r30, 12(%r1)
        stw     %r0, 36(%r1)
        /* Restore U-Boot's r14 and r30 */
        lis     %r11, saved_regs@ha
        addi    %r11, %r11, saved_regs@l
        lwz     %r14, 0(%r11)
        lwz     %r30, 4(%r11)
        /* Enable interrupts */
        mfmsr   %r11
        ori     %r11, %r11, 0x8000@l
        mtmsr   %r11
        /* Call into U-Boot */
        lis     %r11, syscall_ptr@ha
        addi    %r11, %r11, syscall_ptr@l
        lwz     %r11, 0(%r11)
        mtctr   %r11
        bctrl
        /* Disable interrupts */
        mfmsr   %r11
        andi.   %r11, %r11, ~0x8000@l
        mtmsr   %r11
        /* Epilogue */
        lwz     %r11, 0(%r1)
        lwz     %r0, 4(%r11)
        mtlr    %r0
        lwz     %r14, 8(%r1)
        lwz     %r30, 12(%r1)
        mr      %r1, %r11
        blr
END(syscall)

/*
 * Data section
 */
        .data
GLOBAL(syscall_ptr)
        .long   0
GLOBAL(saved_regs)
        .long   0       /* R14 */
        .long   0       /* R30 */
GLOBAL(uboot_address)
        .long   0