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freebsd
GitHub Repository: freebsd/freebsd-src
 Path: blob/main/stand/uboot/arch/powerpc/start.S
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/*-

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 * Copyright (c) 2007 Semihalf, Rafal Jaworowski <[email protected]>

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 * All rights reserved.

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 *

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 * Redistribution and use in source and binary forms, with or without

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 * modification, are permitted provided that the following conditions

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 * are met:

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 * 1. Redistributions of source code must retain the above copyright

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 *    notice, this list of conditions and the following disclaimer.

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 * 2. Redistributions in binary form must reproduce the above copyright

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 *    notice, this list of conditions and the following disclaimer in the

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 *    documentation and/or other materials provided with the distribution.

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 *

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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND

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 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

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 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE

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 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

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 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

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 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

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 * SUCH DAMAGE.

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 */

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#include <machine/asm.h>

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/*

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 * Entry point to the loader that U-Boot passes control to.

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 */

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	.text

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	.globl	_start

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_start:

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	/* Hint where to look for the API signature */

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	lis	%r11, uboot_address@ha

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	addi	%r11, %r11, uboot_address@l

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	stw	%r1, 0(%r11)

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	/* Save U-Boot's r14 and r30 */

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	lis	%r11, saved_regs@ha

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	addi	%r11, %r11, saved_regs@l

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	stw	%r14, 0(%r11)

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	stw	%r30, 4(%r11)

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	/* Disable interrupts */

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	mfmsr	%r11

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	andi.	%r11, %r11, ~0x8000@l

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	mtmsr	%r11

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	b	main

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/*

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 * syscall()

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 */

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ENTRY(syscall)

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	stwu	%r1, -32(%r1)

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	mflr	%r0

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	stw	%r14, 8(%r1)

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	stw	%r30, 12(%r1)

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	stw	%r0, 36(%r1)

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	/* Restore U-Boot's r14 and r30 */

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	lis	%r11, saved_regs@ha

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	addi	%r11, %r11, saved_regs@l

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	lwz	%r14, 0(%r11)

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	lwz	%r30, 4(%r11)

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	/* Enable interrupts */

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	mfmsr	%r11

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	ori	%r11, %r11, 0x8000@l

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	mtmsr	%r11

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	/* Call into U-Boot */

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	lis	%r11, syscall_ptr@ha

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	addi	%r11, %r11, syscall_ptr@l

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	lwz	%r11, 0(%r11)

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	mtctr	%r11

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	bctrl

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	/* Disable interrupts */

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	mfmsr	%r11

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	andi.	%r11, %r11, ~0x8000@l

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	mtmsr	%r11

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	/* Epilogue */

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	lwz	%r11, 0(%r1)

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	lwz	%r0, 4(%r11)

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	mtlr	%r0

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	lwz	%r14, 8(%r1)

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	lwz	%r30, 12(%r1)

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	mr	%r1, %r11

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	blr

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END(syscall)

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/*

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 * Data section

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 */

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	.data

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GLOBAL(syscall_ptr)

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	.long	0

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GLOBAL(saved_regs)

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	.long	0	/* R14 */

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	.long	0	/* R30 */

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GLOBAL(uboot_address)

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	.long	0

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