src/arch/arm/armv4/bootblock.S

/*
 * Early initialization code for ARM architecture.
 *
 * This file is based off of the OMAP3530/ARM Cortex start.S file from Das
 * U-Boot, which itself got the file from armboot.
 *
 * Copyright (c) 2004	Texas Instruments <r-woodruff2@ti.com>
 * Copyright (c) 2001	Marius Gröger <mag@sysgo.de>
 * Copyright (c) 2002	Alex Züpke <azu@sysgo.de>
 * Copyright (c) 2002	Gary Jennejohn <garyj@denx.de>
 * Copyright (c) 2003	Richard Woodruff <r-woodruff2@ti.com>
 * Copyright (c) 2003	Kshitij <kshitij@ti.com>
 * Copyright (c) 2006-2008 Syed Mohammed Khasim <x0khasim@ti.com>
 * Copyright (c) 2013   The Chromium OS Authors
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; version 2 of
 * the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <arch/asm.h>

ENTRY(_start)
	/*
	 * Set the CPU to System mode with IRQ and FIQ disabled. Prefetch/Data
	 * aborts may happen early and crash before the abort handlers are
	 * installed, but at least the problem will show up near the code that
	 * causes it.
	 */
	msr	cpsr_cxf, #0xdf

	/*
	 * Initialize the stack to a known value. This is used to check for
	 * stack overflow later in the boot process.
	 */
	ldr	r0, =_stack
	ldr	r1, =_estack
	ldr	r2, =0xdeadbeef
init_stack_loop:
	str	r2, [r0]
	add	r0, #4
	cmp	r0, r1
	bne	init_stack_loop

/* Set stackpointer in internal RAM to call bootblock main() */
call_bootblock:
	ldr	sp, =_estack /* Set up stack pointer */
	ldr	r0,=0x00000000
	 /*
	  * The current design of cpu_info places the
	  * struct at the top of the stack. The number of
	  * words pushed must be at least as large as that
	  * struct.
	  */
	push	{r0-r2}
	bic	sp, sp, #7 /* 8-byte alignment for ABI compliance */
	/*
	 * Use "bl" instead of "b" even though we do not intend to return.
	 * "bl" gets compiled to "blx" if we're transitioning from ARM to
	 * Thumb. However, "b" will not and GCC may attempt to create a
	 * wrapper which is currently broken.
	 */
	bl	main
ENDPROC(_start)