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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/avr32/boot/u-boot/head.S
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/*

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 * Startup code for use with the u-boot bootloader.

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 *

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 * Copyright (C) 2004-2006 Atmel Corporation

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 *

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 * This program is free software; you can redistribute it and/or modify

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 * it under the terms of the GNU General Public License version 2 as

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 * published by the Free Software Foundation.

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 */

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#include <asm/setup.h>

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	/*

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	 * The kernel is loaded where we want it to be and all caches

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	 * have just been flushed. We get two parameters from u-boot:

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	 *

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	 * r12 contains a magic number (ATAG_MAGIC)

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	 * r11 points to a tag table providing information about

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	 *     the system.

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	 */

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	.section .init.text,"ax"

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	.global _start

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_start:

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	/* Check if the boot loader actually provided a tag table */

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	lddpc	r0, magic_number

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	cp.w	r12, r0

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	brne	no_tag_table

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	/* Initialize .bss */

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	lddpc	r2, bss_start_addr

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	lddpc   r3, end_addr

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	mov	r0, 0

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	mov	r1, 0

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1:      st.d    r2++, r0

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	cp      r2, r3

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	brlo    1b

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	/*

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	 * Save the tag table address for later use. This must be done

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	 * _after_ .bss has been initialized...

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	 */

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	lddpc	r0, tag_table_addr

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	st.w	r0[0], r11

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	/* Jump to loader-independent setup code */

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	rjmp	kernel_entry

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	.align	2

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magic_number:

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	.long	ATAG_MAGIC

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tag_table_addr:

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	.long	bootloader_tags

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bss_start_addr:

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	.long   __bss_start

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end_addr:

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	.long   _end

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no_tag_table:

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	sub	r12, pc, (. - 2f)

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	bral	panic

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2:	.asciz	"Boot loader didn't provide correct magic number\n"

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